Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

28 files changed, 7855 insertions, 0 deletions

diff --git a/tools/objtool/.gitignore b/tools/objtool/.gitignore
new file mode 100644
index 000000000..45cefda24
--- /dev/null
+++ b/tools/objtool/.gitignore
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
+arch/x86/lib/inat-tables.c
+objtool
+fixdep
diff --git a/tools/objtool/Build b/tools/objtool/Build
new file mode 100644
index 000000000..b7222d5cc
--- /dev/null
+++ b/tools/objtool/Build
@@ -0,0 +1,37 @@
+objtool-y += arch/$(SRCARCH)/
+
+objtool-y += weak.o
+
+objtool-$(SUBCMD_CHECK) += check.o
+objtool-$(SUBCMD_CHECK) += special.o
+objtool-$(SUBCMD_ORC) += check.o
+objtool-$(SUBCMD_ORC) += orc_gen.o
+objtool-$(SUBCMD_ORC) += orc_dump.o
+
+objtool-y += builtin-check.o
+objtool-y += builtin-orc.o
+objtool-y += elf.o
+objtool-y += objtool.o
+
+objtool-y += libstring.o
+objtool-y += libctype.o
+objtool-y += str_error_r.o
+objtool-y += librbtree.o
+
+CFLAGS += -I$(srctree)/tools/lib
+
+$(OUTPUT)libstring.o: ../lib/string.c FORCE
+	$(call rule_mkdir)
+	$(call if_changed_dep,cc_o_c)
+
+$(OUTPUT)libctype.o: ../lib/ctype.c FORCE
+	$(call rule_mkdir)
+	$(call if_changed_dep,cc_o_c)
+
+$(OUTPUT)str_error_r.o: ../lib/str_error_r.c FORCE
+	$(call rule_mkdir)
+	$(call if_changed_dep,cc_o_c)
+
+$(OUTPUT)librbtree.o: ../lib/rbtree.c FORCE
+	$(call rule_mkdir)
+	$(call if_changed_dep,cc_o_c)
diff --git a/tools/objtool/Documentation/stack-validation.txt b/tools/objtool/Documentation/stack-validation.txt
new file mode 100644
index 000000000..30f38fdc0
--- /dev/null
+++ b/tools/objtool/Documentation/stack-validation.txt
@@ -0,0 +1,360 @@
+Compile-time stack metadata validation
+======================================
+
+
+Overview
+--------
+
+The kernel CONFIG_STACK_VALIDATION option enables a host tool named
+objtool which runs at compile time.  It has a "check" subcommand which
+analyzes every .o file and ensures the validity of its stack metadata.
+It enforces a set of rules on asm code and C inline assembly code so
+that stack traces can be reliable.
+
+For each function, it recursively follows all possible code paths and
+validates the correct frame pointer state at each instruction.
+
+It also follows code paths involving special sections, like
+.altinstructions, __jump_table, and __ex_table, which can add
+alternative execution paths to a given instruction (or set of
+instructions).  Similarly, it knows how to follow switch statements, for
+which gcc sometimes uses jump tables.
+
+(Objtool also has an 'orc generate' subcommand which generates debuginfo
+for the ORC unwinder.  See Documentation/x86/orc-unwinder.rst in the
+kernel tree for more details.)
+
+
+Why do we need stack metadata validation?
+-----------------------------------------
+
+Here are some of the benefits of validating stack metadata:
+
+a) More reliable stack traces for frame pointer enabled kernels
+
+   Frame pointers are used for debugging purposes.  They allow runtime
+   code and debug tools to be able to walk the stack to determine the
+   chain of function call sites that led to the currently executing
+   code.
+
+   For some architectures, frame pointers are enabled by
+   CONFIG_FRAME_POINTER.  For some other architectures they may be
+   required by the ABI (sometimes referred to as "backchain pointers").
+
+   For C code, gcc automatically generates instructions for setting up
+   frame pointers when the -fno-omit-frame-pointer option is used.
+
+   But for asm code, the frame setup instructions have to be written by
+   hand, which most people don't do.  So the end result is that
+   CONFIG_FRAME_POINTER is honored for C code but not for most asm code.
+
+   For stack traces based on frame pointers to be reliable, all
+   functions which call other functions must first create a stack frame
+   and update the frame pointer.  If a first function doesn't properly
+   create a stack frame before calling a second function, the *caller*
+   of the first function will be skipped on the stack trace.
+
+   For example, consider the following example backtrace with frame
+   pointers enabled:
+
+     [<ffffffff81812584>] dump_stack+0x4b/0x63
+     [<ffffffff812d6dc2>] cmdline_proc_show+0x12/0x30
+     [<ffffffff8127f568>] seq_read+0x108/0x3e0
+     [<ffffffff812cce62>] proc_reg_read+0x42/0x70
+     [<ffffffff81256197>] __vfs_read+0x37/0x100
+     [<ffffffff81256b16>] vfs_read+0x86/0x130
+     [<ffffffff81257898>] SyS_read+0x58/0xd0
+     [<ffffffff8181c1f2>] entry_SYSCALL_64_fastpath+0x12/0x76
+
+   It correctly shows that the caller of cmdline_proc_show() is
+   seq_read().
+
+   If we remove the frame pointer logic from cmdline_proc_show() by
+   replacing the frame pointer related instructions with nops, here's
+   what it looks like instead:
+
+     [<ffffffff81812584>] dump_stack+0x4b/0x63
+     [<ffffffff812d6dc2>] cmdline_proc_show+0x12/0x30
+     [<ffffffff812cce62>] proc_reg_read+0x42/0x70
+     [<ffffffff81256197>] __vfs_read+0x37/0x100
+     [<ffffffff81256b16>] vfs_read+0x86/0x130
+     [<ffffffff81257898>] SyS_read+0x58/0xd0
+     [<ffffffff8181c1f2>] entry_SYSCALL_64_fastpath+0x12/0x76
+
+   Notice that cmdline_proc_show()'s caller, seq_read(), has been
+   skipped.  Instead the stack trace seems to show that
+   cmdline_proc_show() was called by proc_reg_read().
+
+   The benefit of objtool here is that because it ensures that *all*
+   functions honor CONFIG_FRAME_POINTER, no functions will ever[*] be
+   skipped on a stack trace.
+
+   [*] unless an interrupt or exception has occurred at the very
+       beginning of a function before the stack frame has been created,
+       or at the very end of the function after the stack frame has been
+       destroyed.  This is an inherent limitation of frame pointers.
+
+b) ORC (Oops Rewind Capability) unwind table generation
+
+   An alternative to frame pointers and DWARF, ORC unwind data can be
+   used to walk the stack.  Unlike frame pointers, ORC data is out of
+   band.  So it doesn't affect runtime performance and it can be
+   reliable even when interrupts or exceptions are involved.
+
+   For more details, see Documentation/x86/orc-unwinder.rst.
+
+c) Higher live patching compatibility rate
+
+   Livepatch has an optional "consistency model", which is needed for
+   more complex patches.  In order for the consistency model to work,
+   stack traces need to be reliable (or an unreliable condition needs to
+   be detectable).  Objtool makes that possible.
+
+   For more details, see the livepatch documentation in the Linux kernel
+   source tree at Documentation/livepatch/livepatch.rst.
+
+Rules
+-----
+
+To achieve the validation, objtool enforces the following rules:
+
+1. Each callable function must be annotated as such with the ELF
+   function type.  In asm code, this is typically done using the
+   ENTRY/ENDPROC macros.  If objtool finds a return instruction
+   outside of a function, it flags an error since that usually indicates
+   callable code which should be annotated accordingly.
+
+   This rule is needed so that objtool can properly identify each
+   callable function in order to analyze its stack metadata.
+
+2. Conversely, each section of code which is *not* callable should *not*
+   be annotated as an ELF function.  The ENDPROC macro shouldn't be used
+   in this case.
+
+   This rule is needed so that objtool can ignore non-callable code.
+   Such code doesn't have to follow any of the other rules.
+
+3. Each callable function which calls another function must have the
+   correct frame pointer logic, if required by CONFIG_FRAME_POINTER or
+   the architecture's back chain rules.  This can by done in asm code
+   with the FRAME_BEGIN/FRAME_END macros.
+
+   This rule ensures that frame pointer based stack traces will work as
+   designed.  If function A doesn't create a stack frame before calling
+   function B, the _caller_ of function A will be skipped on the stack
+   trace.
+
+4. Dynamic jumps and jumps to undefined symbols are only allowed if:
+
+   a) the jump is part of a switch statement; or
+
+   b) the jump matches sibling call semantics and the frame pointer has
+      the same value it had on function entry.
+
+   This rule is needed so that objtool can reliably analyze all of a
+   function's code paths.  If a function jumps to code in another file,
+   and it's not a sibling call, objtool has no way to follow the jump
+   because it only analyzes a single file at a time.
+
+5. A callable function may not execute kernel entry/exit instructions.
+   The only code which needs such instructions is kernel entry code,
+   which shouldn't be be in callable functions anyway.
+
+   This rule is just a sanity check to ensure that callable functions
+   return normally.
+
+
+Objtool warnings
+----------------
+
+For asm files, if you're getting an error which doesn't make sense,
+first make sure that the affected code follows the above rules.
+
+For C files, the common culprits are inline asm statements and calls to
+"noreturn" functions.  See below for more details.
+
+Another possible cause for errors in C code is if the Makefile removes
+-fno-omit-frame-pointer or adds -fomit-frame-pointer to the gcc options.
+
+Here are some examples of common warnings reported by objtool, what
+they mean, and suggestions for how to fix them.
+
+
+1. file.o: warning: objtool: func()+0x128: call without frame pointer save/setup
+
+   The func() function made a function call without first saving and/or
+   updating the frame pointer, and CONFIG_FRAME_POINTER is enabled.
+
+   If the error is for an asm file, and func() is indeed a callable
+   function, add proper frame pointer logic using the FRAME_BEGIN and
+   FRAME_END macros.  Otherwise, if it's not a callable function, remove
+   its ELF function annotation by changing ENDPROC to END, and instead
+   use the manual unwind hint macros in asm/unwind_hints.h.
+
+   If it's a GCC-compiled .c file, the error may be because the function
+   uses an inline asm() statement which has a "call" instruction.  An
+   asm() statement with a call instruction must declare the use of the
+   stack pointer in its output operand.  On x86_64, this means adding
+   the ASM_CALL_CONSTRAINT as an output constraint:
+
+     asm volatile("call func" : ASM_CALL_CONSTRAINT);
+
+   Otherwise the stack frame may not get created before the call.
+
+
+2. file.o: warning: objtool: .text+0x53: unreachable instruction
+
+   Objtool couldn't find a code path to reach the instruction.
+
+   If the error is for an asm file, and the instruction is inside (or
+   reachable from) a callable function, the function should be annotated
+   with the ENTRY/ENDPROC macros (ENDPROC is the important one).
+   Otherwise, the code should probably be annotated with the unwind hint
+   macros in asm/unwind_hints.h so objtool and the unwinder can know the
+   stack state associated with the code.
+
+   If you're 100% sure the code won't affect stack traces, or if you're
+   a just a bad person, you can tell objtool to ignore it.  See the
+   "Adding exceptions" section below.
+
+   If it's not actually in a callable function (e.g. kernel entry code),
+   change ENDPROC to END.
+
+
+4. file.o: warning: objtool: func(): can't find starting instruction
+   or
+   file.o: warning: objtool: func()+0x11dd: can't decode instruction
+
+   Does the file have data in a text section?  If so, that can confuse
+   objtool's instruction decoder.  Move the data to a more appropriate
+   section like .data or .rodata.
+
+
+5. file.o: warning: objtool: func()+0x6: unsupported instruction in callable function
+
+   This is a kernel entry/exit instruction like sysenter or iret.  Such
+   instructions aren't allowed in a callable function, and are most
+   likely part of the kernel entry code.  They should usually not have
+   the callable function annotation (ENDPROC) and should always be
+   annotated with the unwind hint macros in asm/unwind_hints.h.
+
+
+6. file.o: warning: objtool: func()+0x26: sibling call from callable instruction with modified stack frame
+
+   This is a dynamic jump or a jump to an undefined symbol.  Objtool
+   assumed it's a sibling call and detected that the frame pointer
+   wasn't first restored to its original state.
+
+   If it's not really a sibling call, you may need to move the
+   destination code to the local file.
+
+   If the instruction is not actually in a callable function (e.g.
+   kernel entry code), change ENDPROC to END and annotate manually with
+   the unwind hint macros in asm/unwind_hints.h.
+
+
+7. file: warning: objtool: func()+0x5c: stack state mismatch
+
+   The instruction's frame pointer state is inconsistent, depending on
+   which execution path was taken to reach the instruction.
+
+   Make sure that, when CONFIG_FRAME_POINTER is enabled, the function
+   pushes and sets up the frame pointer (for x86_64, this means rbp) at
+   the beginning of the function and pops it at the end of the function.
+   Also make sure that no other code in the function touches the frame
+   pointer.
+
+   Another possibility is that the code has some asm or inline asm which
+   does some unusual things to the stack or the frame pointer.  In such
+   cases it's probably appropriate to use the unwind hint macros in
+   asm/unwind_hints.h.
+
+
+8. file.o: warning: objtool: funcA() falls through to next function funcB()
+
+   This means that funcA() doesn't end with a return instruction or an
+   unconditional jump, and that objtool has determined that the function
+   can fall through into the next function.  There could be different
+   reasons for this:
+
+   1) funcA()'s last instruction is a call to a "noreturn" function like
+      panic().  In this case the noreturn function needs to be added to
+      objtool's hard-coded global_noreturns array.  Feel free to bug the
+      objtool maintainer, or you can submit a patch.
+
+   2) funcA() uses the unreachable() annotation in a section of code
+      that is actually reachable.
+
+   3) If funcA() calls an inline function, the object code for funcA()
+      might be corrupt due to a gcc bug.  For more details, see:
+      https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70646
+
+9. file.o: warning: objtool: funcA() call to funcB() with UACCESS enabled
+
+   This means that an unexpected call to a non-whitelisted function exists
+   outside of arch-specific guards.
+   X86: SMAP (stac/clac): __uaccess_begin()/__uaccess_end()
+   ARM: PAN: uaccess_enable()/uaccess_disable()
+
+   These functions should be called to denote a minimal critical section around
+   access to __user variables. See also: https://lwn.net/Articles/517475/
+
+   The intention of the warning is to prevent calls to funcB() from eventually
+   calling schedule(), potentially leaking the AC flags state, and not
+   restoring them correctly.
+
+   It also helps verify that there are no unexpected calls to funcB() which may
+   access user space pages with protections against doing so disabled.
+
+   To fix, either:
+   1) remove explicit calls to funcB() from funcA().
+   2) add the correct guards before and after calls to low level functions like
+      __get_user_size()/__put_user_size().
+   3) add funcB to uaccess_safe_builtin whitelist in tools/objtool/check.c, if
+      funcB obviously does not call schedule(), and is marked notrace (since
+      function tracing inserts additional calls, which is not obvious from the
+      sources).
+
+10. file.o: warning: func()+0x5c: stack layout conflict in alternatives
+
+    This means that in the use of the alternative() or ALTERNATIVE()
+    macro, the code paths have conflicting modifications to the stack.
+    The problem is that there is only one ORC unwind table, which means
+    that the ORC unwind entries must be consistent for all possible
+    instruction boundaries regardless of which code has been patched.
+    This limitation can be overcome by massaging the alternatives with
+    NOPs to shift the stack changes around so they no longer conflict.
+
+11. file.o: warning: unannotated intra-function call
+
+   This warning means that a direct call is done to a destination which
+   is not at the beginning of a function. If this is a legit call, you
+   can remove this warning by putting the ANNOTATE_INTRA_FUNCTION_CALL
+   directive right before the call.
+
+
+If the error doesn't seem to make sense, it could be a bug in objtool.
+Feel free to ask the objtool maintainer for help.
+
+
+Adding exceptions
+-----------------
+
+If you _really_ need objtool to ignore something, and are 100% sure
+that it won't affect kernel stack traces, you can tell objtool to
+ignore it:
+
+- To skip validation of a function, use the STACK_FRAME_NON_STANDARD
+  macro.
+
+- To skip validation of a file, add
+
+    OBJECT_FILES_NON_STANDARD_filename.o := y
+
+  to the Makefile.
+
+- To skip validation of a directory, add
+
+    OBJECT_FILES_NON_STANDARD := y
+
+  to the Makefile.
diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
new file mode 100644
index 000000000..a43096f71
--- /dev/null
+++ b/tools/objtool/Makefile
@@ -0,0 +1,71 @@
+# SPDX-License-Identifier: GPL-2.0
+include ../scripts/Makefile.include
+include ../scripts/Makefile.arch
+
+# always use the host compiler
+AR	 = $(HOSTAR)
+CC	 = $(HOSTCC)
+LD	 = $(HOSTLD)
+
+ifeq ($(srctree),)
+srctree := $(patsubst %/,%,$(dir $(CURDIR)))
+srctree := $(patsubst %/,%,$(dir $(srctree)))
+endif
+
+SUBCMD_SRCDIR		= $(srctree)/tools/lib/subcmd/
+LIBSUBCMD_OUTPUT	= $(if $(OUTPUT),$(OUTPUT),$(CURDIR)/)
+LIBSUBCMD		= $(LIBSUBCMD_OUTPUT)libsubcmd.a
+
+OBJTOOL    := $(OUTPUT)objtool
+OBJTOOL_IN := $(OBJTOOL)-in.o
+
+LIBELF_FLAGS := $(shell pkg-config libelf --cflags 2>/dev/null)
+LIBELF_LIBS  := $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
+
+all: $(OBJTOOL)
+
+INCLUDES := -I$(srctree)/tools/include \
+	    -I$(srctree)/tools/arch/$(HOSTARCH)/include/uapi \
+	    -I$(srctree)/tools/arch/$(SRCARCH)/include	\
+	    -I$(srctree)/tools/objtool/arch/$(SRCARCH)/include
+WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed -Wno-nested-externs
+CFLAGS   := -Werror $(WARNINGS) $(KBUILD_HOSTCFLAGS) -g $(INCLUDES) $(LIBELF_FLAGS)
+LDFLAGS  += $(LIBELF_LIBS) $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS)
+
+# Allow old libelf to be used:
+elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(CC) $(CFLAGS) -x c -E - | grep elf_getshdr)
+CFLAGS += $(if $(elfshdr),,-DLIBELF_USE_DEPRECATED)
+
+AWK = awk
+
+SUBCMD_CHECK := n
+SUBCMD_ORC := n
+
+ifeq ($(SRCARCH),x86)
+	SUBCMD_CHECK := y
+	SUBCMD_ORC := y
+endif
+
+export SUBCMD_CHECK SUBCMD_ORC
+export srctree OUTPUT CFLAGS SRCARCH AWK
+include $(srctree)/tools/build/Makefile.include
+
+$(OBJTOOL_IN): fixdep FORCE
+	@$(CONFIG_SHELL) ./sync-check.sh
+	@$(MAKE) $(build)=objtool
+
+$(OBJTOOL): $(LIBSUBCMD) $(OBJTOOL_IN)
+	$(QUIET_LINK)$(CC) $(OBJTOOL_IN) $(LDFLAGS) -o $@
+
+
+$(LIBSUBCMD): fixdep FORCE
+	$(Q)$(MAKE) -C $(SUBCMD_SRCDIR) OUTPUT=$(LIBSUBCMD_OUTPUT)
+
+clean:
+	$(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL)
+	$(Q)find $(OUTPUT) -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
+	$(Q)$(RM) $(OUTPUT)arch/x86/inat-tables.c $(OUTPUT)fixdep
+
+FORCE:
+
+.PHONY: clean FORCE
diff --git a/tools/objtool/arch.h b/tools/objtool/arch.h
new file mode 100644
index 000000000..75840291b
--- /dev/null
+++ b/tools/objtool/arch.h
@@ -0,0 +1,97 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#ifndef _ARCH_H
+#define _ARCH_H
+
+#include <stdbool.h>
+#include <linux/list.h>
+#include "objtool.h"
+#include "cfi.h"
+
+enum insn_type {
+	INSN_JUMP_CONDITIONAL,
+	INSN_JUMP_UNCONDITIONAL,
+	INSN_JUMP_DYNAMIC,
+	INSN_JUMP_DYNAMIC_CONDITIONAL,
+	INSN_CALL,
+	INSN_CALL_DYNAMIC,
+	INSN_RETURN,
+	INSN_CONTEXT_SWITCH,
+	INSN_BUG,
+	INSN_NOP,
+	INSN_STAC,
+	INSN_CLAC,
+	INSN_STD,
+	INSN_CLD,
+	INSN_TRAP,
+	INSN_OTHER,
+};
+
+enum op_dest_type {
+	OP_DEST_REG,
+	OP_DEST_REG_INDIRECT,
+	OP_DEST_MEM,
+	OP_DEST_PUSH,
+	OP_DEST_PUSHF,
+	OP_DEST_LEAVE,
+};
+
+struct op_dest {
+	enum op_dest_type type;
+	unsigned char reg;
+	int offset;
+};
+
+enum op_src_type {
+	OP_SRC_REG,
+	OP_SRC_REG_INDIRECT,
+	OP_SRC_CONST,
+	OP_SRC_POP,
+	OP_SRC_POPF,
+	OP_SRC_ADD,
+	OP_SRC_AND,
+};
+
+struct op_src {
+	enum op_src_type type;
+	unsigned char reg;
+	int offset;
+};
+
+struct stack_op {
+	struct op_dest dest;
+	struct op_src src;
+	struct list_head list;
+};
+
+struct instruction;
+
+void arch_initial_func_cfi_state(struct cfi_init_state *state);
+
+int arch_decode_instruction(const struct elf *elf, const struct section *sec,
+			    unsigned long offset, unsigned int maxlen,
+			    unsigned int *len, enum insn_type *type,
+			    unsigned long *immediate,
+			    struct list_head *ops_list);
+
+bool arch_callee_saved_reg(unsigned char reg);
+
+unsigned long arch_jump_destination(struct instruction *insn);
+
+unsigned long arch_dest_reloc_offset(int addend);
+
+const char *arch_nop_insn(int len);
+const char *arch_ret_insn(int len);
+
+int arch_decode_hint_reg(u8 sp_reg, int *base);
+
+bool arch_is_retpoline(struct symbol *sym);
+bool arch_is_rethunk(struct symbol *sym);
+bool arch_is_embedded_insn(struct symbol *sym);
+
+int arch_rewrite_retpolines(struct objtool_file *file);
+
+#endif /* _ARCH_H */
diff --git a/tools/objtool/arch/x86/Build b/tools/objtool/arch/x86/Build
new file mode 100644
index 000000000..9f7869b5c
--- /dev/null
+++ b/tools/objtool/arch/x86/Build
@@ -0,0 +1,13 @@
+objtool-y += special.o
+objtool-y += decode.o
+
+inat_tables_script = ../arch/x86/tools/gen-insn-attr-x86.awk
+inat_tables_maps = ../arch/x86/lib/x86-opcode-map.txt
+
+$(OUTPUT)arch/x86/lib/inat-tables.c: $(inat_tables_script) $(inat_tables_maps)
+	$(call rule_mkdir)
+	$(Q)$(call echo-cmd,gen)$(AWK) -f $(inat_tables_script) $(inat_tables_maps) > $@
+
+$(OUTPUT)arch/x86/decode.o: $(OUTPUT)arch/x86/lib/inat-tables.c
+
+CFLAGS_decode.o += -I$(OUTPUT)arch/x86/lib
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
new file mode 100644
index 000000000..9d2af6767
--- /dev/null
+++ b/tools/objtool/arch/x86/decode.c
@@ -0,0 +1,662 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#define unlikely(cond) (cond)
+#include <asm/insn.h>
+#include "../../../arch/x86/lib/inat.c"
+#include "../../../arch/x86/lib/insn.c"
+
+#include "../../check.h"
+#include "../../elf.h"
+#include "../../arch.h"
+#include "../../warn.h"
+#include <asm/orc_types.h>
+#include "arch_elf.h"
+
+static unsigned char op_to_cfi_reg[][2] = {
+	{CFI_AX, CFI_R8},
+	{CFI_CX, CFI_R9},
+	{CFI_DX, CFI_R10},
+	{CFI_BX, CFI_R11},
+	{CFI_SP, CFI_R12},
+	{CFI_BP, CFI_R13},
+	{CFI_SI, CFI_R14},
+	{CFI_DI, CFI_R15},
+};
+
+static int is_x86_64(const struct elf *elf)
+{
+	switch (elf->ehdr.e_machine) {
+	case EM_X86_64:
+		return 1;
+	case EM_386:
+		return 0;
+	default:
+		WARN("unexpected ELF machine type %d", elf->ehdr.e_machine);
+		return -1;
+	}
+}
+
+bool arch_callee_saved_reg(unsigned char reg)
+{
+	switch (reg) {
+	case CFI_BP:
+	case CFI_BX:
+	case CFI_R12:
+	case CFI_R13:
+	case CFI_R14:
+	case CFI_R15:
+		return true;
+
+	case CFI_AX:
+	case CFI_CX:
+	case CFI_DX:
+	case CFI_SI:
+	case CFI_DI:
+	case CFI_SP:
+	case CFI_R8:
+	case CFI_R9:
+	case CFI_R10:
+	case CFI_R11:
+	case CFI_RA:
+	default:
+		return false;
+	}
+}
+
+unsigned long arch_dest_reloc_offset(int addend)
+{
+	return addend + 4;
+}
+
+unsigned long arch_jump_destination(struct instruction *insn)
+{
+	return insn->offset + insn->len + insn->immediate;
+}
+
+#define ADD_OP(op) \
+	if (!(op = calloc(1, sizeof(*op)))) \
+		return -1; \
+	else for (list_add_tail(&op->list, ops_list); op; op = NULL)
+
+int arch_decode_instruction(const struct elf *elf, const struct section *sec,
+			    unsigned long offset, unsigned int maxlen,
+			    unsigned int *len, enum insn_type *type,
+			    unsigned long *immediate,
+			    struct list_head *ops_list)
+{
+	struct insn insn;
+	int x86_64, sign;
+	unsigned char op1, op2, rex = 0, rex_b = 0, rex_r = 0, rex_w = 0,
+		      rex_x = 0, modrm = 0, modrm_mod = 0, modrm_rm = 0,
+		      modrm_reg = 0, sib = 0;
+	struct stack_op *op = NULL;
+	struct symbol *sym;
+
+	x86_64 = is_x86_64(elf);
+	if (x86_64 == -1)
+		return -1;
+
+	insn_init(&insn, sec->data->d_buf + offset, maxlen, x86_64);
+	insn_get_length(&insn);
+
+	if (!insn_complete(&insn)) {
+		WARN("can't decode instruction at %s:0x%lx", sec->name, offset);
+		return -1;
+	}
+
+	*len = insn.length;
+	*type = INSN_OTHER;
+
+	if (insn.vex_prefix.nbytes)
+		return 0;
+
+	op1 = insn.opcode.bytes[0];
+	op2 = insn.opcode.bytes[1];
+
+	if (insn.rex_prefix.nbytes) {
+		rex = insn.rex_prefix.bytes[0];
+		rex_w = X86_REX_W(rex) >> 3;
+		rex_r = X86_REX_R(rex) >> 2;
+		rex_x = X86_REX_X(rex) >> 1;
+		rex_b = X86_REX_B(rex);
+	}
+
+	if (insn.modrm.nbytes) {
+		modrm = insn.modrm.bytes[0];
+		modrm_mod = X86_MODRM_MOD(modrm);
+		modrm_reg = X86_MODRM_REG(modrm);
+		modrm_rm = X86_MODRM_RM(modrm);
+	}
+
+	if (insn.sib.nbytes)
+		sib = insn.sib.bytes[0];
+
+	switch (op1) {
+
+	case 0x1:
+	case 0x29:
+		if (rex_w && !rex_b && modrm_mod == 3 && modrm_rm == 4) {
+
+			/* add/sub reg, %rsp */
+			ADD_OP(op) {
+				op->src.type = OP_SRC_ADD;
+				op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
+				op->dest.type = OP_DEST_REG;
+				op->dest.reg = CFI_SP;
+			}
+		}
+		break;
+
+	case 0x50 ... 0x57:
+
+		/* push reg */
+		ADD_OP(op) {
+			op->src.type = OP_SRC_REG;
+			op->src.reg = op_to_cfi_reg[op1 & 0x7][rex_b];
+			op->dest.type = OP_DEST_PUSH;
+		}
+
+		break;
+
+	case 0x58 ... 0x5f:
+
+		/* pop reg */
+		ADD_OP(op) {
+			op->src.type = OP_SRC_POP;
+			op->dest.type = OP_DEST_REG;
+			op->dest.reg = op_to_cfi_reg[op1 & 0x7][rex_b];
+		}
+
+		break;
+
+	case 0x68:
+	case 0x6a:
+		/* push immediate */
+		ADD_OP(op) {
+			op->src.type = OP_SRC_CONST;
+			op->dest.type = OP_DEST_PUSH;
+		}
+		break;
+
+	case 0x70 ... 0x7f:
+		*type = INSN_JUMP_CONDITIONAL;
+		break;
+
+	case 0x81:
+	case 0x83:
+		if (rex != 0x48)
+			break;
+
+		if (modrm == 0xe4) {
+			/* and imm, %rsp */
+			ADD_OP(op) {
+				op->src.type = OP_SRC_AND;
+				op->src.reg = CFI_SP;
+				op->src.offset = insn.immediate.value;
+				op->dest.type = OP_DEST_REG;
+				op->dest.reg = CFI_SP;
+			}
+			break;
+		}
+
+		if (modrm == 0xc4)
+			sign = 1;
+		else if (modrm == 0xec)
+			sign = -1;
+		else
+			break;
+
+		/* add/sub imm, %rsp */
+		ADD_OP(op) {
+			op->src.type = OP_SRC_ADD;
+			op->src.reg = CFI_SP;
+			op->src.offset = insn.immediate.value * sign;
+			op->dest.type = OP_DEST_REG;
+			op->dest.reg = CFI_SP;
+		}
+		break;
+
+	case 0x89:
+		if (rex_w && !rex_r && modrm_mod == 3 && modrm_reg == 4) {
+
+			/* mov %rsp, reg */
+			ADD_OP(op) {
+				op->src.type = OP_SRC_REG;
+				op->src.reg = CFI_SP;
+				op->dest.type = OP_DEST_REG;
+				op->dest.reg = op_to_cfi_reg[modrm_rm][rex_b];
+			}
+			break;
+		}
+
+		if (rex_w && !rex_b && modrm_mod == 3 && modrm_rm == 4) {
+
+			/* mov reg, %rsp */
+			ADD_OP(op) {
+				op->src.type = OP_SRC_REG;
+				op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
+				op->dest.type = OP_DEST_REG;
+				op->dest.reg = CFI_SP;
+			}
+			break;
+		}
+
+		/* fallthrough */
+	case 0x88:
+		if (!rex_b &&
+		    (modrm_mod == 1 || modrm_mod == 2) && modrm_rm == 5) {
+
+			/* mov reg, disp(%rbp) */
+			ADD_OP(op) {
+				op->src.type = OP_SRC_REG;
+				op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
+				op->dest.type = OP_DEST_REG_INDIRECT;
+				op->dest.reg = CFI_BP;
+				op->dest.offset = insn.displacement.value;
+			}
+
+		} else if (rex_w && !rex_b && modrm_rm == 4 && sib == 0x24) {
+
+			/* mov reg, disp(%rsp) */
+			ADD_OP(op) {
+				op->src.type = OP_SRC_REG;
+				op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
+				op->dest.type = OP_DEST_REG_INDIRECT;
+				op->dest.reg = CFI_SP;
+				op->dest.offset = insn.displacement.value;
+			}
+		}
+
+		break;
+
+	case 0x8b:
+		if (rex_w && !rex_b && modrm_mod == 1 && modrm_rm == 5) {
+
+			/* mov disp(%rbp), reg */
+			ADD_OP(op) {
+				op->src.type = OP_SRC_REG_INDIRECT;
+				op->src.reg = CFI_BP;
+				op->src.offset = insn.displacement.value;
+				op->dest.type = OP_DEST_REG;
+				op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r];
+			}
+
+		} else if (rex_w && !rex_b && sib == 0x24 &&
+			   modrm_mod != 3 && modrm_rm == 4) {
+
+			/* mov disp(%rsp), reg */
+			ADD_OP(op) {
+				op->src.type = OP_SRC_REG_INDIRECT;
+				op->src.reg = CFI_SP;
+				op->src.offset = insn.displacement.value;
+				op->dest.type = OP_DEST_REG;
+				op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r];
+			}
+		}
+
+		break;
+
+	case 0x8d:
+		if (sib == 0x24 && rex_w && !rex_b && !rex_x) {
+
+			ADD_OP(op) {
+				if (!insn.displacement.value) {
+					/* lea (%rsp), reg */
+					op->src.type = OP_SRC_REG;
+				} else {
+					/* lea disp(%rsp), reg */
+					op->src.type = OP_SRC_ADD;
+					op->src.offset = insn.displacement.value;
+				}
+				op->src.reg = CFI_SP;
+				op->dest.type = OP_DEST_REG;
+				op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r];
+			}
+
+		} else if (rex == 0x48 && modrm == 0x65) {
+
+			/* lea disp(%rbp), %rsp */
+			ADD_OP(op) {
+				op->src.type = OP_SRC_ADD;
+				op->src.reg = CFI_BP;
+				op->src.offset = insn.displacement.value;
+				op->dest.type = OP_DEST_REG;
+				op->dest.reg = CFI_SP;
+			}
+
+		} else if (rex == 0x49 && modrm == 0x62 &&
+			   insn.displacement.value == -8) {
+
+			/*
+			 * lea -0x8(%r10), %rsp
+			 *
+			 * Restoring rsp back to its original value after a
+			 * stack realignment.
+			 */
+			ADD_OP(op) {
+				op->src.type = OP_SRC_ADD;
+				op->src.reg = CFI_R10;
+				op->src.offset = -8;
+				op->dest.type = OP_DEST_REG;
+				op->dest.reg = CFI_SP;
+			}
+
+		} else if (rex == 0x49 && modrm == 0x65 &&
+			   insn.displacement.value == -16) {
+
+			/*
+			 * lea -0x10(%r13), %rsp
+			 *
+			 * Restoring rsp back to its original value after a
+			 * stack realignment.
+			 */
+			ADD_OP(op) {
+				op->src.type = OP_SRC_ADD;
+				op->src.reg = CFI_R13;
+				op->src.offset = -16;
+				op->dest.type = OP_DEST_REG;
+				op->dest.reg = CFI_SP;
+			}
+		}
+
+		break;
+
+	case 0x8f:
+		/* pop to mem */
+		ADD_OP(op) {
+			op->src.type = OP_SRC_POP;
+			op->dest.type = OP_DEST_MEM;
+		}
+		break;
+
+	case 0x90:
+		*type = INSN_NOP;
+		break;
+
+	case 0x9c:
+		/* pushf */
+		ADD_OP(op) {
+			op->src.type = OP_SRC_CONST;
+			op->dest.type = OP_DEST_PUSHF;
+		}
+		break;
+
+	case 0x9d:
+		/* popf */
+		ADD_OP(op) {
+			op->src.type = OP_SRC_POPF;
+			op->dest.type = OP_DEST_MEM;
+		}
+		break;
+
+	case 0x0f:
+
+		if (op2 == 0x01) {
+
+			if (modrm == 0xca)
+				*type = INSN_CLAC;
+			else if (modrm == 0xcb)
+				*type = INSN_STAC;
+
+		} else if (op2 >= 0x80 && op2 <= 0x8f) {
+
+			*type = INSN_JUMP_CONDITIONAL;
+
+		} else if (op2 == 0x05 || op2 == 0x07 || op2 == 0x34 ||
+			   op2 == 0x35) {
+
+			/* sysenter, sysret */
+			*type = INSN_CONTEXT_SWITCH;
+
+		} else if (op2 == 0x0b || op2 == 0xb9) {
+
+			/* ud2 */
+			*type = INSN_BUG;
+
+		} else if (op2 == 0x0d || op2 == 0x1f) {
+
+			/* nopl/nopw */
+			*type = INSN_NOP;
+
+		} else if (op2 == 0xa0 || op2 == 0xa8) {
+
+			/* push fs/gs */
+			ADD_OP(op) {
+				op->src.type = OP_SRC_CONST;
+				op->dest.type = OP_DEST_PUSH;
+			}
+
+		} else if (op2 == 0xa1 || op2 == 0xa9) {
+
+			/* pop fs/gs */
+			ADD_OP(op) {
+				op->src.type = OP_SRC_POP;
+				op->dest.type = OP_DEST_MEM;
+			}
+		}
+
+		break;
+
+	case 0xc9:
+		/*
+		 * leave
+		 *
+		 * equivalent to:
+		 * mov bp, sp
+		 * pop bp
+		 */
+		ADD_OP(op)
+			op->dest.type = OP_DEST_LEAVE;
+
+		break;
+
+	case 0xcc:
+		/* int3 */
+		*type = INSN_TRAP;
+		break;
+
+	case 0xe3:
+		/* jecxz/jrcxz */
+		*type = INSN_JUMP_CONDITIONAL;
+		break;
+
+	case 0xe9:
+	case 0xeb:
+		*type = INSN_JUMP_UNCONDITIONAL;
+		break;
+
+	case 0xc2:
+	case 0xc3:
+		*type = INSN_RETURN;
+		break;
+
+	case 0xcf: /* iret */
+		/*
+		 * Handle sync_core(), which has an IRET to self.
+		 * All other IRET are in STT_NONE entry code.
+		 */
+		sym = find_symbol_containing(sec, offset);
+		if (sym && sym->type == STT_FUNC) {
+			ADD_OP(op) {
+				/* add $40, %rsp */
+				op->src.type = OP_SRC_ADD;
+				op->src.reg = CFI_SP;
+				op->src.offset = 5*8;
+				op->dest.type = OP_DEST_REG;
+				op->dest.reg = CFI_SP;
+			}
+			break;
+		}
+
+		/* fallthrough */
+
+	case 0xca: /* retf */
+	case 0xcb: /* retf */
+		*type = INSN_CONTEXT_SWITCH;
+		break;
+
+	case 0xe8:
+		*type = INSN_CALL;
+		/*
+		 * For the impact on the stack, a CALL behaves like
+		 * a PUSH of an immediate value (the return address).
+		 */
+		ADD_OP(op) {
+			op->src.type = OP_SRC_CONST;
+			op->dest.type = OP_DEST_PUSH;
+		}
+		break;
+
+	case 0xfc:
+		*type = INSN_CLD;
+		break;
+
+	case 0xfd:
+		*type = INSN_STD;
+		break;
+
+	case 0xff:
+		if (modrm_reg == 2 || modrm_reg == 3)
+
+			*type = INSN_CALL_DYNAMIC;
+
+		else if (modrm_reg == 4)
+
+			*type = INSN_JUMP_DYNAMIC;
+
+		else if (modrm_reg == 5)
+
+			/* jmpf */
+			*type = INSN_CONTEXT_SWITCH;
+
+		else if (modrm_reg == 6) {
+
+			/* push from mem */
+			ADD_OP(op) {
+				op->src.type = OP_SRC_CONST;
+				op->dest.type = OP_DEST_PUSH;
+			}
+		}
+
+		break;
+
+	default:
+		break;
+	}
+
+	*immediate = insn.immediate.nbytes ? insn.immediate.value : 0;
+
+	return 0;
+}
+
+void arch_initial_func_cfi_state(struct cfi_init_state *state)
+{
+	int i;
+
+	for (i = 0; i < CFI_NUM_REGS; i++) {
+		state->regs[i].base = CFI_UNDEFINED;
+		state->regs[i].offset = 0;
+	}
+
+	/* initial CFA (call frame address) */
+	state->cfa.base = CFI_SP;
+	state->cfa.offset = 8;
+
+	/* initial RA (return address) */
+	state->regs[CFI_RA].base = CFI_CFA;
+	state->regs[CFI_RA].offset = -8;
+}
+
+const char *arch_nop_insn(int len)
+{
+	static const char nops[5][5] = {
+		/* 1 */ { 0x90 },
+		/* 2 */ { 0x66, 0x90 },
+		/* 3 */ { 0x0f, 0x1f, 0x00 },
+		/* 4 */ { 0x0f, 0x1f, 0x40, 0x00 },
+		/* 5 */ { 0x0f, 0x1f, 0x44, 0x00, 0x00 },
+	};
+
+	if (len < 1 || len > 5) {
+		WARN("invalid NOP size: %d\n", len);
+		return NULL;
+	}
+
+	return nops[len-1];
+}
+
+#define BYTE_RET	0xC3
+
+const char *arch_ret_insn(int len)
+{
+	static const char ret[5][5] = {
+		{ BYTE_RET },
+		{ BYTE_RET, 0xcc },
+		{ BYTE_RET, 0xcc, 0x90 },
+		{ BYTE_RET, 0xcc, 0x66, 0x90 },
+		{ BYTE_RET, 0xcc, 0x0f, 0x1f, 0x00 },
+	};
+
+	if (len < 1 || len > 5) {
+		WARN("invalid RET size: %d\n", len);
+		return NULL;
+	}
+
+	return ret[len-1];
+}
+
+int arch_decode_hint_reg(u8 sp_reg, int *base)
+{
+	switch (sp_reg) {
+	case ORC_REG_UNDEFINED:
+		*base = CFI_UNDEFINED;
+		break;
+	case ORC_REG_SP:
+		*base = CFI_SP;
+		break;
+	case ORC_REG_BP:
+		*base = CFI_BP;
+		break;
+	case ORC_REG_SP_INDIRECT:
+		*base = CFI_SP_INDIRECT;
+		break;
+	case ORC_REG_R10:
+		*base = CFI_R10;
+		break;
+	case ORC_REG_R13:
+		*base = CFI_R13;
+		break;
+	case ORC_REG_DI:
+		*base = CFI_DI;
+		break;
+	case ORC_REG_DX:
+		*base = CFI_DX;
+		break;
+	default:
+		return -1;
+	}
+
+	return 0;
+}
+
+bool arch_is_retpoline(struct symbol *sym)
+{
+	return !strncmp(sym->name, "__x86_indirect_", 15);
+}
+
+bool arch_is_rethunk(struct symbol *sym)
+{
+	return !strcmp(sym->name, "__x86_return_thunk");
+}
+
+bool arch_is_embedded_insn(struct symbol *sym)
+{
+	return !strcmp(sym->name, "retbleed_return_thunk") ||
+	       !strcmp(sym->name, "srso_safe_ret");
+}
diff --git a/tools/objtool/arch/x86/include/arch_elf.h b/tools/objtool/arch/x86/include/arch_elf.h
new file mode 100644
index 000000000..69cc4264b
--- /dev/null
+++ b/tools/objtool/arch/x86/include/arch_elf.h
@@ -0,0 +1,6 @@
+#ifndef _OBJTOOL_ARCH_ELF
+#define _OBJTOOL_ARCH_ELF
+
+#define R_NONE R_X86_64_NONE
+
+#endif /* _OBJTOOL_ARCH_ELF */
diff --git a/tools/objtool/arch/x86/include/arch_special.h b/tools/objtool/arch/x86/include/arch_special.h
new file mode 100644
index 000000000..14271cca0
--- /dev/null
+++ b/tools/objtool/arch/x86/include/arch_special.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _X86_ARCH_SPECIAL_H
+#define _X86_ARCH_SPECIAL_H
+
+#define EX_ENTRY_SIZE		12
+#define EX_ORIG_OFFSET		0
+#define EX_NEW_OFFSET		4
+
+#define JUMP_ENTRY_SIZE		16
+#define JUMP_ORIG_OFFSET	0
+#define JUMP_NEW_OFFSET		4
+
+#define ALT_ENTRY_SIZE		12
+#define ALT_ORIG_OFFSET		0
+#define ALT_NEW_OFFSET		4
+#define ALT_FEATURE_OFFSET	8
+#define ALT_ORIG_LEN_OFFSET	10
+#define ALT_NEW_LEN_OFFSET	11
+
+#endif /* _X86_ARCH_SPECIAL_H */
diff --git a/tools/objtool/arch/x86/include/cfi_regs.h b/tools/objtool/arch/x86/include/cfi_regs.h
new file mode 100644
index 000000000..79bc517ef
--- /dev/null
+++ b/tools/objtool/arch/x86/include/cfi_regs.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _OBJTOOL_CFI_REGS_H
+#define _OBJTOOL_CFI_REGS_H
+
+#define CFI_AX			0
+#define CFI_DX			1
+#define CFI_CX			2
+#define CFI_BX			3
+#define CFI_SI			4
+#define CFI_DI			5
+#define CFI_BP			6
+#define CFI_SP			7
+#define CFI_R8			8
+#define CFI_R9			9
+#define CFI_R10			10
+#define CFI_R11			11
+#define CFI_R12			12
+#define CFI_R13			13
+#define CFI_R14			14
+#define CFI_R15			15
+#define CFI_RA			16
+#define CFI_NUM_REGS		17
+
+#endif /* _OBJTOOL_CFI_REGS_H */
diff --git a/tools/objtool/arch/x86/special.c b/tools/objtool/arch/x86/special.c
new file mode 100644
index 000000000..151b13d0a
--- /dev/null
+++ b/tools/objtool/arch/x86/special.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <string.h>
+
+#include "../../special.h"
+#include "../../builtin.h"
+
+#define X86_FEATURE_POPCNT (4 * 32 + 23)
+#define X86_FEATURE_SMAP   (9 * 32 + 20)
+
+void arch_handle_alternative(unsigned short feature, struct special_alt *alt)
+{
+	switch (feature) {
+	case X86_FEATURE_SMAP:
+		/*
+		 * If UACCESS validation is enabled; force that alternative;
+		 * otherwise force it the other way.
+		 *
+		 * What we want to avoid is having both the original and the
+		 * alternative code flow at the same time, in that case we can
+		 * find paths that see the STAC but take the NOP instead of
+		 * CLAC and the other way around.
+		 */
+		if (uaccess)
+			alt->skip_orig = true;
+		else
+			alt->skip_alt = true;
+		break;
+	case X86_FEATURE_POPCNT:
+		/*
+		 * It has been requested that we don't validate the !POPCNT
+		 * feature path which is a "very very small percentage of
+		 * machines".
+		 */
+		alt->skip_orig = true;
+		break;
+	default:
+		break;
+	}
+}
+
+bool arch_support_alt_relocation(struct special_alt *special_alt,
+				 struct instruction *insn,
+				 struct reloc *reloc)
+{
+	/*
+	 * The x86 alternatives code adjusts the offsets only when it
+	 * encounters a branch instruction at the very beginning of the
+	 * replacement group.
+	 */
+	return insn->offset == special_alt->new_off &&
+	       (insn->type == INSN_CALL || is_jump(insn));
+}
+
+/*
+ * There are 3 basic jump table patterns:
+ *
+ * 1. jmpq *[rodata addr](,%reg,8)
+ *
+ *    This is the most common case by far.  It jumps to an address in a simple
+ *    jump table which is stored in .rodata.
+ *
+ * 2. jmpq *[rodata addr](%rip)
+ *
+ *    This is caused by a rare GCC quirk, currently only seen in three driver
+ *    functions in the kernel, only with certain obscure non-distro configs.
+ *
+ *    As part of an optimization, GCC makes a copy of an existing switch jump
+ *    table, modifies it, and then hard-codes the jump (albeit with an indirect
+ *    jump) to use a single entry in the table.  The rest of the jump table and
+ *    some of its jump targets remain as dead code.
+ *
+ *    In such a case we can just crudely ignore all unreachable instruction
+ *    warnings for the entire object file.  Ideally we would just ignore them
+ *    for the function, but that would require redesigning the code quite a
+ *    bit.  And honestly that's just not worth doing: unreachable instruction
+ *    warnings are of questionable value anyway, and this is such a rare issue.
+ *
+ * 3. mov [rodata addr],%reg1
+ *    ... some instructions ...
+ *    jmpq *(%reg1,%reg2,8)
+ *
+ *    This is a fairly uncommon pattern which is new for GCC 6.  As of this
+ *    writing, there are 11 occurrences of it in the allmodconfig kernel.
+ *
+ *    As of GCC 7 there are quite a few more of these and the 'in between' code
+ *    is significant. Esp. with KASAN enabled some of the code between the mov
+ *    and jmpq uses .rodata itself, which can confuse things.
+ *
+ *    TODO: Once we have DWARF CFI and smarter instruction decoding logic,
+ *    ensure the same register is used in the mov and jump instructions.
+ *
+ *    NOTE: RETPOLINE made it harder still to decode dynamic jumps.
+ */
+struct reloc *arch_find_switch_table(struct objtool_file *file,
+				    struct instruction *insn)
+{
+	struct reloc  *text_reloc, *rodata_reloc;
+	struct section *table_sec;
+	unsigned long table_offset;
+
+	/* look for a relocation which references .rodata */
+	text_reloc = find_reloc_by_dest_range(file->elf, insn->sec,
+					      insn->offset, insn->len);
+	if (!text_reloc || text_reloc->sym->type != STT_SECTION ||
+	    !text_reloc->sym->sec->rodata)
+		return NULL;
+
+	table_offset = text_reloc->addend;
+	table_sec = text_reloc->sym->sec;
+
+	if (text_reloc->type == R_X86_64_PC32)
+		table_offset += 4;
+
+	/*
+	 * Make sure the .rodata address isn't associated with a
+	 * symbol.  GCC jump tables are anonymous data.
+	 *
+	 * Also support C jump tables which are in the same format as
+	 * switch jump tables.  For objtool to recognize them, they
+	 * need to be placed in the C_JUMP_TABLE_SECTION section.  They
+	 * have symbols associated with them.
+	 */
+	if (find_symbol_containing(table_sec, table_offset) &&
+	    strcmp(table_sec->name, C_JUMP_TABLE_SECTION))
+		return NULL;
+
+	/*
+	 * Each table entry has a rela associated with it.  The rela
+	 * should reference text in the same function as the original
+	 * instruction.
+	 */
+	rodata_reloc = find_reloc_by_dest(file->elf, table_sec, table_offset);
+	if (!rodata_reloc)
+		return NULL;
+
+	/*
+	 * Use of RIP-relative switch jumps is quite rare, and
+	 * indicates a rare GCC quirk/bug which can leave dead
+	 * code behind.
+	 */
+	if (text_reloc->type == R_X86_64_PC32)
+		file->ignore_unreachables = true;
+
+	return rodata_reloc;
+}
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
new file mode 100644
index 000000000..447a49c03
--- /dev/null
+++ b/tools/objtool/builtin-check.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+/*
+ * objtool check:
+ *
+ * This command analyzes every .o file and ensures the validity of its stack
+ * trace metadata.  It enforces a set of rules on asm code and C inline
+ * assembly code so that stack traces can be reliable.
+ *
+ * For more information, see tools/objtool/Documentation/stack-validation.txt.
+ */
+
+#include <subcmd/parse-options.h>
+#include <string.h>
+#include "builtin.h"
+#include "objtool.h"
+
+bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats,
+     validate_dup, vmlinux, sls, unret, rethunk;
+
+static const char * const check_usage[] = {
+	"objtool check [<options>] file.o",
+	NULL,
+};
+
+const struct option check_options[] = {
+	OPT_BOOLEAN('f', "no-fp", &no_fp, "Skip frame pointer validation"),
+	OPT_BOOLEAN('u', "no-unreachable", &no_unreachable, "Skip 'unreachable instruction' warnings"),
+	OPT_BOOLEAN('r', "retpoline", &retpoline, "Validate retpoline assumptions"),
+	OPT_BOOLEAN(0,   "rethunk", &rethunk, "validate and annotate rethunk usage"),
+	OPT_BOOLEAN(0,   "unret", &unret, "validate entry unret placement"),
+	OPT_BOOLEAN('m', "module", &module, "Indicates the object will be part of a kernel module"),
+	OPT_BOOLEAN('b', "backtrace", &backtrace, "unwind on error"),
+	OPT_BOOLEAN('a', "uaccess", &uaccess, "enable uaccess checking"),
+	OPT_BOOLEAN('s', "stats", &stats, "print statistics"),
+	OPT_BOOLEAN('d', "duplicate", &validate_dup, "duplicate validation for vmlinux.o"),
+	OPT_BOOLEAN('l', "vmlinux", &vmlinux, "vmlinux.o validation"),
+	OPT_BOOLEAN('S', "sls", &sls, "validate straight-line-speculation"),
+	OPT_END(),
+};
+
+int cmd_check(int argc, const char **argv)
+{
+	const char *objname, *s;
+	struct objtool_file *file;
+	int ret;
+
+	argc = parse_options(argc, argv, check_options, check_usage, 0);
+
+	if (argc != 1)
+		usage_with_options(check_usage, check_options);
+
+	objname = argv[0];
+
+	s = strstr(objname, "vmlinux.o");
+	if (s && !s[9])
+		vmlinux = true;
+
+	file = objtool_open_read(objname);
+	if (!file)
+		return 1;
+
+	ret = check(file);
+	if (ret)
+		return ret;
+
+	if (file->elf->changed)
+		return elf_write(file->elf);
+
+	return 0;
+}
diff --git a/tools/objtool/builtin-orc.c b/tools/objtool/builtin-orc.c
new file mode 100644
index 000000000..508bdf6ae
--- /dev/null
+++ b/tools/objtool/builtin-orc.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+/*
+ * objtool orc:
+ *
+ * This command analyzes a .o file and adds .orc_unwind and .orc_unwind_ip
+ * sections to it, which is used by the in-kernel ORC unwinder.
+ *
+ * This command is a superset of "objtool check".
+ */
+
+#include <string.h>
+#include "builtin.h"
+#include "objtool.h"
+
+static const char *orc_usage[] = {
+	"objtool orc generate [<options>] file.o",
+	"objtool orc dump file.o",
+	NULL,
+};
+
+int cmd_orc(int argc, const char **argv)
+{
+	const char *objname;
+
+	argc--; argv++;
+	if (argc <= 0)
+		usage_with_options(orc_usage, check_options);
+
+	if (!strncmp(argv[0], "gen", 3)) {
+		struct objtool_file *file;
+		int ret;
+
+		argc = parse_options(argc, argv, check_options, orc_usage, 0);
+		if (argc != 1)
+			usage_with_options(orc_usage, check_options);
+
+		objname = argv[0];
+
+		file = objtool_open_read(objname);
+		if (!file)
+			return 1;
+
+		ret = check(file);
+		if (ret)
+			return ret;
+
+		if (list_empty(&file->insn_list))
+			return 0;
+
+		ret = orc_create(file);
+		if (ret)
+			return ret;
+
+		if (!file->elf->changed)
+			return 0;
+
+		return elf_write(file->elf);
+	}
+
+	if (!strcmp(argv[0], "dump")) {
+		if (argc != 2)
+			usage_with_options(orc_usage, check_options);
+
+		objname = argv[1];
+
+		return orc_dump(objname);
+	}
+
+	usage_with_options(orc_usage, check_options);
+
+	return 0;
+}
diff --git a/tools/objtool/builtin.h b/tools/objtool/builtin.h
new file mode 100644
index 000000000..61d8d49db
--- /dev/null
+++ b/tools/objtool/builtin.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+#ifndef _BUILTIN_H
+#define _BUILTIN_H
+
+#include <subcmd/parse-options.h>
+
+extern const struct option check_options[];
+extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats,
+            validate_dup, vmlinux, sls, unret, rethunk;
+
+extern int cmd_check(int argc, const char **argv);
+extern int cmd_orc(int argc, const char **argv);
+
+#endif /* _BUILTIN_H */
diff --git a/tools/objtool/cfi.h b/tools/objtool/cfi.h
new file mode 100644
index 000000000..f579802d7
--- /dev/null
+++ b/tools/objtool/cfi.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#ifndef _OBJTOOL_CFI_H
+#define _OBJTOOL_CFI_H
+
+#include "cfi_regs.h"
+#include <linux/list.h>
+
+#define CFI_UNDEFINED		-1
+#define CFI_CFA			-2
+#define CFI_SP_INDIRECT		-3
+#define CFI_BP_INDIRECT		-4
+
+struct cfi_reg {
+	int base;
+	int offset;
+};
+
+struct cfi_init_state {
+	struct cfi_reg regs[CFI_NUM_REGS];
+	struct cfi_reg cfa;
+};
+
+struct cfi_state {
+	struct hlist_node hash; /* must be first, cficmp() */
+	struct cfi_reg regs[CFI_NUM_REGS];
+	struct cfi_reg vals[CFI_NUM_REGS];
+	struct cfi_reg cfa;
+	int stack_size;
+	int drap_reg, drap_offset;
+	unsigned char type;
+	bool bp_scratch;
+	bool drap;
+	bool end;
+};
+
+#endif /* _OBJTOOL_CFI_H */
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
new file mode 100644
index 000000000..059b78d08
--- /dev/null
+++ b/tools/objtool/check.c
@@ -0,0 +1,3603 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <sys/mman.h>
+
+#include "builtin.h"
+#include "cfi.h"
+#include "arch.h"
+#include "check.h"
+#include "special.h"
+#include "warn.h"
+#include "arch_elf.h"
+
+#include <linux/objtool.h>
+#include <linux/hashtable.h>
+#include <linux/kernel.h>
+#include <linux/static_call_types.h>
+
+struct alternative {
+	struct list_head list;
+	struct instruction *insn;
+	bool skip_orig;
+};
+
+static unsigned long nr_cfi, nr_cfi_reused, nr_cfi_cache;
+
+static struct cfi_init_state initial_func_cfi;
+static struct cfi_state init_cfi;
+static struct cfi_state func_cfi;
+
+struct instruction *find_insn(struct objtool_file *file,
+			      struct section *sec, unsigned long offset)
+{
+	struct instruction *insn;
+
+	hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) {
+		if (insn->sec == sec && insn->offset == offset)
+			return insn;
+	}
+
+	return NULL;
+}
+
+static struct instruction *next_insn_same_sec(struct objtool_file *file,
+					      struct instruction *insn)
+{
+	struct instruction *next = list_next_entry(insn, list);
+
+	if (!next || &next->list == &file->insn_list || next->sec != insn->sec)
+		return NULL;
+
+	return next;
+}
+
+static struct instruction *next_insn_same_func(struct objtool_file *file,
+					       struct instruction *insn)
+{
+	struct instruction *next = list_next_entry(insn, list);
+	struct symbol *func = insn->func;
+
+	if (!func)
+		return NULL;
+
+	if (&next->list != &file->insn_list && next->func == func)
+		return next;
+
+	/* Check if we're already in the subfunction: */
+	if (func == func->cfunc)
+		return NULL;
+
+	/* Move to the subfunction: */
+	return find_insn(file, func->cfunc->sec, func->cfunc->offset);
+}
+
+static struct instruction *prev_insn_same_sym(struct objtool_file *file,
+					       struct instruction *insn)
+{
+	struct instruction *prev = list_prev_entry(insn, list);
+
+	if (&prev->list != &file->insn_list && prev->func == insn->func)
+		return prev;
+
+	return NULL;
+}
+
+#define func_for_each_insn(file, func, insn)				\
+	for (insn = find_insn(file, func->sec, func->offset);		\
+	     insn;							\
+	     insn = next_insn_same_func(file, insn))
+
+#define sym_for_each_insn(file, sym, insn)				\
+	for (insn = find_insn(file, sym->sec, sym->offset);		\
+	     insn && &insn->list != &file->insn_list &&			\
+		insn->sec == sym->sec &&				\
+		insn->offset < sym->offset + sym->len;			\
+	     insn = list_next_entry(insn, list))
+
+#define sym_for_each_insn_continue_reverse(file, sym, insn)		\
+	for (insn = list_prev_entry(insn, list);			\
+	     &insn->list != &file->insn_list &&				\
+		insn->sec == sym->sec && insn->offset >= sym->offset;	\
+	     insn = list_prev_entry(insn, list))
+
+#define sec_for_each_insn_from(file, insn)				\
+	for (; insn; insn = next_insn_same_sec(file, insn))
+
+#define sec_for_each_insn_continue(file, insn)				\
+	for (insn = next_insn_same_sec(file, insn); insn;		\
+	     insn = next_insn_same_sec(file, insn))
+
+static bool is_jump_table_jump(struct instruction *insn)
+{
+	struct alt_group *alt_group = insn->alt_group;
+
+	if (insn->jump_table)
+		return true;
+
+	/* Retpoline alternative for a jump table? */
+	return alt_group && alt_group->orig_group &&
+	       alt_group->orig_group->first_insn->jump_table;
+}
+
+static bool is_sibling_call(struct instruction *insn)
+{
+	/*
+	 * Assume only ELF functions can make sibling calls.  This ensures
+	 * sibling call detection consistency between vmlinux.o and individual
+	 * objects.
+	 */
+	if (!insn->func)
+		return false;
+
+	/* An indirect jump is either a sibling call or a jump to a table. */
+	if (insn->type == INSN_JUMP_DYNAMIC)
+		return !is_jump_table_jump(insn);
+
+	/* add_jump_destinations() sets insn->call_dest for sibling calls. */
+	return (is_static_jump(insn) && insn->call_dest);
+}
+
+/*
+ * This checks to see if the given function is a "noreturn" function.
+ *
+ * For global functions which are outside the scope of this object file, we
+ * have to keep a manual list of them.
+ *
+ * For local functions, we have to detect them manually by simply looking for
+ * the lack of a return instruction.
+ */
+static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
+				int recursion)
+{
+	int i;
+	struct instruction *insn;
+	bool empty = true;
+
+	/*
+	 * Unfortunately these have to be hard coded because the noreturn
+	 * attribute isn't provided in ELF data.
+	 */
+	static const char * const global_noreturns[] = {
+		"__stack_chk_fail",
+		"panic",
+		"do_exit",
+		"do_task_dead",
+		"make_task_dead",
+		"__module_put_and_exit",
+		"complete_and_exit",
+		"__reiserfs_panic",
+		"lbug_with_loc",
+		"fortify_panic",
+		"usercopy_abort",
+		"machine_real_restart",
+		"rewind_stack_and_make_dead",
+		"kunit_try_catch_throw",
+		"xen_start_kernel",
+		"cpu_bringup_and_idle",
+		"stop_this_cpu",
+	};
+
+	if (!func)
+		return false;
+
+	if (func->bind == STB_WEAK)
+		return false;
+
+	if (func->bind == STB_GLOBAL)
+		for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
+			if (!strcmp(func->name, global_noreturns[i]))
+				return true;
+
+	if (!func->len)
+		return false;
+
+	insn = find_insn(file, func->sec, func->offset);
+	if (!insn || !insn->func)
+		return false;
+
+	func_for_each_insn(file, func, insn) {
+		empty = false;
+
+		if (insn->type == INSN_RETURN)
+			return false;
+	}
+
+	if (empty)
+		return false;
+
+	/*
+	 * A function can have a sibling call instead of a return.  In that
+	 * case, the function's dead-end status depends on whether the target
+	 * of the sibling call returns.
+	 */
+	func_for_each_insn(file, func, insn) {
+		if (is_sibling_call(insn)) {
+			struct instruction *dest = insn->jump_dest;
+
+			if (!dest)
+				/* sibling call to another file */
+				return false;
+
+			/* local sibling call */
+			if (recursion == 5) {
+				/*
+				 * Infinite recursion: two functions have
+				 * sibling calls to each other.  This is a very
+				 * rare case.  It means they aren't dead ends.
+				 */
+				return false;
+			}
+
+			return __dead_end_function(file, dest->func, recursion+1);
+		}
+	}
+
+	return true;
+}
+
+static bool dead_end_function(struct objtool_file *file, struct symbol *func)
+{
+	return __dead_end_function(file, func, 0);
+}
+
+static void init_cfi_state(struct cfi_state *cfi)
+{
+	int i;
+
+	for (i = 0; i < CFI_NUM_REGS; i++) {
+		cfi->regs[i].base = CFI_UNDEFINED;
+		cfi->vals[i].base = CFI_UNDEFINED;
+	}
+	cfi->cfa.base = CFI_UNDEFINED;
+	cfi->drap_reg = CFI_UNDEFINED;
+	cfi->drap_offset = -1;
+}
+
+static void init_insn_state(struct insn_state *state, struct section *sec)
+{
+	memset(state, 0, sizeof(*state));
+	init_cfi_state(&state->cfi);
+
+	/*
+	 * We need the full vmlinux for noinstr validation, otherwise we can
+	 * not correctly determine insn->call_dest->sec (external symbols do
+	 * not have a section).
+	 */
+	if (vmlinux && sec)
+		state->noinstr = sec->noinstr;
+}
+
+static struct cfi_state *cfi_alloc(void)
+{
+	struct cfi_state *cfi = calloc(sizeof(struct cfi_state), 1);
+	if (!cfi) {
+		WARN("calloc failed");
+		exit(1);
+	}
+	nr_cfi++;
+	return cfi;
+}
+
+static int cfi_bits;
+static struct hlist_head *cfi_hash;
+
+static inline bool cficmp(struct cfi_state *cfi1, struct cfi_state *cfi2)
+{
+	return memcmp((void *)cfi1 + sizeof(cfi1->hash),
+		      (void *)cfi2 + sizeof(cfi2->hash),
+		      sizeof(struct cfi_state) - sizeof(struct hlist_node));
+}
+
+static inline u32 cfi_key(struct cfi_state *cfi)
+{
+	return jhash((void *)cfi + sizeof(cfi->hash),
+		     sizeof(*cfi) - sizeof(cfi->hash), 0);
+}
+
+static struct cfi_state *cfi_hash_find_or_add(struct cfi_state *cfi)
+{
+	struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
+	struct cfi_state *obj;
+
+	hlist_for_each_entry(obj, head, hash) {
+		if (!cficmp(cfi, obj)) {
+			nr_cfi_cache++;
+			return obj;
+		}
+	}
+
+	obj = cfi_alloc();
+	*obj = *cfi;
+	hlist_add_head(&obj->hash, head);
+
+	return obj;
+}
+
+static void cfi_hash_add(struct cfi_state *cfi)
+{
+	struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
+
+	hlist_add_head(&cfi->hash, head);
+}
+
+static void *cfi_hash_alloc(void)
+{
+	cfi_bits = vmlinux ? ELF_HASH_BITS - 3 : 13;
+	cfi_hash = mmap(NULL, sizeof(struct hlist_head) << cfi_bits,
+			PROT_READ|PROT_WRITE,
+			MAP_PRIVATE|MAP_ANON, -1, 0);
+	if (cfi_hash == (void *)-1L) {
+		WARN("mmap fail cfi_hash");
+		cfi_hash = NULL;
+	}  else if (stats) {
+		printf("cfi_bits: %d\n", cfi_bits);
+	}
+
+	return cfi_hash;
+}
+
+static unsigned long nr_insns;
+static unsigned long nr_insns_visited;
+
+/*
+ * Call the arch-specific instruction decoder for all the instructions and add
+ * them to the global instruction list.
+ */
+static int decode_instructions(struct objtool_file *file)
+{
+	struct section *sec;
+	struct symbol *func;
+	unsigned long offset;
+	struct instruction *insn;
+	int ret;
+
+	for_each_sec(file, sec) {
+
+		if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+			continue;
+
+		if (strcmp(sec->name, ".altinstr_replacement") &&
+		    strcmp(sec->name, ".altinstr_aux") &&
+		    strncmp(sec->name, ".discard.", 9))
+			sec->text = true;
+
+		if (!strcmp(sec->name, ".noinstr.text") ||
+		    !strcmp(sec->name, ".entry.text") ||
+		    !strncmp(sec->name, ".text..__x86.", 13))
+			sec->noinstr = true;
+
+		for (offset = 0; offset < sec->len; offset += insn->len) {
+			insn = malloc(sizeof(*insn));
+			if (!insn) {
+				WARN("malloc failed");
+				return -1;
+			}
+			memset(insn, 0, sizeof(*insn));
+			INIT_LIST_HEAD(&insn->alts);
+			INIT_LIST_HEAD(&insn->stack_ops);
+
+			insn->sec = sec;
+			insn->offset = offset;
+
+			ret = arch_decode_instruction(file->elf, sec, offset,
+						      sec->len - offset,
+						      &insn->len, &insn->type,
+						      &insn->immediate,
+						      &insn->stack_ops);
+			if (ret)
+				goto err;
+
+			hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
+			list_add_tail(&insn->list, &file->insn_list);
+			nr_insns++;
+		}
+
+		list_for_each_entry(func, &sec->symbol_list, list) {
+			if (func->type != STT_FUNC || func->alias != func)
+				continue;
+
+			if (!find_insn(file, sec, func->offset)) {
+				WARN("%s(): can't find starting instruction",
+				     func->name);
+				return -1;
+			}
+
+			sym_for_each_insn(file, func, insn)
+				insn->func = func;
+		}
+	}
+
+	if (stats)
+		printf("nr_insns: %lu\n", nr_insns);
+
+	return 0;
+
+err:
+	free(insn);
+	return ret;
+}
+
+static struct instruction *find_last_insn(struct objtool_file *file,
+					  struct section *sec)
+{
+	struct instruction *insn = NULL;
+	unsigned int offset;
+	unsigned int end = (sec->len > 10) ? sec->len - 10 : 0;
+
+	for (offset = sec->len - 1; offset >= end && !insn; offset--)
+		insn = find_insn(file, sec, offset);
+
+	return insn;
+}
+
+/*
+ * Mark "ud2" instructions and manually annotated dead ends.
+ */
+static int add_dead_ends(struct objtool_file *file)
+{
+	struct section *sec;
+	struct reloc *reloc;
+	struct instruction *insn;
+
+	/*
+	 * By default, "ud2" is a dead end unless otherwise annotated, because
+	 * GCC 7 inserts it for certain divide-by-zero cases.
+	 */
+	for_each_insn(file, insn)
+		if (insn->type == INSN_BUG)
+			insn->dead_end = true;
+
+	/*
+	 * Check for manually annotated dead ends.
+	 */
+	sec = find_section_by_name(file->elf, ".rela.discard.unreachable");
+	if (!sec)
+		goto reachable;
+
+	list_for_each_entry(reloc, &sec->reloc_list, list) {
+		if (reloc->sym->type != STT_SECTION) {
+			WARN("unexpected relocation symbol type in %s", sec->name);
+			return -1;
+		}
+		insn = find_insn(file, reloc->sym->sec, reloc->addend);
+		if (insn)
+			insn = list_prev_entry(insn, list);
+		else if (reloc->addend == reloc->sym->sec->len) {
+			insn = find_last_insn(file, reloc->sym->sec);
+			if (!insn) {
+				WARN("can't find unreachable insn at %s+0x%" PRIx64,
+				     reloc->sym->sec->name, reloc->addend);
+				return -1;
+			}
+		} else {
+			WARN("can't find unreachable insn at %s+0x%" PRIx64,
+			     reloc->sym->sec->name, reloc->addend);
+			return -1;
+		}
+
+		insn->dead_end = true;
+	}
+
+reachable:
+	/*
+	 * These manually annotated reachable checks are needed for GCC 4.4,
+	 * where the Linux unreachable() macro isn't supported.  In that case
+	 * GCC doesn't know the "ud2" is fatal, so it generates code as if it's
+	 * not a dead end.
+	 */
+	sec = find_section_by_name(file->elf, ".rela.discard.reachable");
+	if (!sec)
+		return 0;
+
+	list_for_each_entry(reloc, &sec->reloc_list, list) {
+		if (reloc->sym->type != STT_SECTION) {
+			WARN("unexpected relocation symbol type in %s", sec->name);
+			return -1;
+		}
+		insn = find_insn(file, reloc->sym->sec, reloc->addend);
+		if (insn)
+			insn = list_prev_entry(insn, list);
+		else if (reloc->addend == reloc->sym->sec->len) {
+			insn = find_last_insn(file, reloc->sym->sec);
+			if (!insn) {
+				WARN("can't find reachable insn at %s+0x%" PRIx64,
+				     reloc->sym->sec->name, reloc->addend);
+				return -1;
+			}
+		} else {
+			WARN("can't find reachable insn at %s+0x%" PRIx64,
+			     reloc->sym->sec->name, reloc->addend);
+			return -1;
+		}
+
+		insn->dead_end = false;
+	}
+
+	return 0;
+}
+
+static int create_static_call_sections(struct objtool_file *file)
+{
+	struct section *sec;
+	struct static_call_site *site;
+	struct instruction *insn;
+	struct symbol *key_sym;
+	char *key_name, *tmp;
+	int idx;
+
+	sec = find_section_by_name(file->elf, ".static_call_sites");
+	if (sec) {
+		INIT_LIST_HEAD(&file->static_call_list);
+		WARN("file already has .static_call_sites section, skipping");
+		return 0;
+	}
+
+	if (list_empty(&file->static_call_list))
+		return 0;
+
+	idx = 0;
+	list_for_each_entry(insn, &file->static_call_list, call_node)
+		idx++;
+
+	sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE,
+				 sizeof(struct static_call_site), idx);
+	if (!sec)
+		return -1;
+
+	idx = 0;
+	list_for_each_entry(insn, &file->static_call_list, call_node) {
+
+		site = (struct static_call_site *)sec->data->d_buf + idx;
+		memset(site, 0, sizeof(struct static_call_site));
+
+		/* populate reloc for 'addr' */
+		if (elf_add_reloc_to_insn(file->elf, sec,
+					  idx * sizeof(struct static_call_site),
+					  R_X86_64_PC32,
+					  insn->sec, insn->offset))
+			return -1;
+
+		/* find key symbol */
+		key_name = strdup(insn->call_dest->name);
+		if (!key_name) {
+			perror("strdup");
+			return -1;
+		}
+		if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR,
+			    STATIC_CALL_TRAMP_PREFIX_LEN)) {
+			WARN("static_call: trampoline name malformed: %s", key_name);
+			free(key_name);
+			return -1;
+		}
+		tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN;
+		memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN);
+
+		key_sym = find_symbol_by_name(file->elf, tmp);
+		if (!key_sym) {
+			if (!module) {
+				WARN("static_call: can't find static_call_key symbol: %s", tmp);
+				free(key_name);
+				return -1;
+			}
+
+			/*
+			 * For modules(), the key might not be exported, which
+			 * means the module can make static calls but isn't
+			 * allowed to change them.
+			 *
+			 * In that case we temporarily set the key to be the
+			 * trampoline address.  This is fixed up in
+			 * static_call_add_module().
+			 */
+			key_sym = insn->call_dest;
+		}
+		free(key_name);
+
+		/* populate reloc for 'key' */
+		if (elf_add_reloc(file->elf, sec,
+				  idx * sizeof(struct static_call_site) + 4,
+				  R_X86_64_PC32, key_sym,
+				  is_sibling_call(insn) * STATIC_CALL_SITE_TAIL))
+			return -1;
+
+		idx++;
+	}
+
+	return 0;
+}
+
+static int create_retpoline_sites_sections(struct objtool_file *file)
+{
+	struct instruction *insn;
+	struct section *sec;
+	int idx;
+
+	sec = find_section_by_name(file->elf, ".retpoline_sites");
+	if (sec) {
+		WARN("file already has .retpoline_sites, skipping");
+		return 0;
+	}
+
+	idx = 0;
+	list_for_each_entry(insn, &file->retpoline_call_list, call_node)
+		idx++;
+
+	if (!idx)
+		return 0;
+
+	sec = elf_create_section(file->elf, ".retpoline_sites", 0,
+				 sizeof(int), idx);
+	if (!sec) {
+		WARN("elf_create_section: .retpoline_sites");
+		return -1;
+	}
+
+	idx = 0;
+	list_for_each_entry(insn, &file->retpoline_call_list, call_node) {
+
+		int *site = (int *)sec->data->d_buf + idx;
+		*site = 0;
+
+		if (elf_add_reloc_to_insn(file->elf, sec,
+					  idx * sizeof(int),
+					  R_X86_64_PC32,
+					  insn->sec, insn->offset)) {
+			WARN("elf_add_reloc_to_insn: .retpoline_sites");
+			return -1;
+		}
+
+		idx++;
+	}
+
+	return 0;
+}
+
+static int create_return_sites_sections(struct objtool_file *file)
+{
+	struct instruction *insn;
+	struct section *sec;
+	int idx;
+
+	sec = find_section_by_name(file->elf, ".return_sites");
+	if (sec) {
+		WARN("file already has .return_sites, skipping");
+		return 0;
+	}
+
+	idx = 0;
+	list_for_each_entry(insn, &file->return_thunk_list, call_node)
+		idx++;
+
+	if (!idx)
+		return 0;
+
+	sec = elf_create_section(file->elf, ".return_sites", 0,
+				 sizeof(int), idx);
+	if (!sec) {
+		WARN("elf_create_section: .return_sites");
+		return -1;
+	}
+
+	idx = 0;
+	list_for_each_entry(insn, &file->return_thunk_list, call_node) {
+
+		int *site = (int *)sec->data->d_buf + idx;
+		*site = 0;
+
+		if (elf_add_reloc_to_insn(file->elf, sec,
+					  idx * sizeof(int),
+					  R_X86_64_PC32,
+					  insn->sec, insn->offset)) {
+			WARN("elf_add_reloc_to_insn: .return_sites");
+			return -1;
+		}
+
+		idx++;
+	}
+
+	return 0;
+}
+
+/*
+ * Warnings shouldn't be reported for ignored functions.
+ */
+static void add_ignores(struct objtool_file *file)
+{
+	struct instruction *insn;
+	struct section *sec;
+	struct symbol *func;
+	struct reloc *reloc;
+
+	sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard");
+	if (!sec)
+		return;
+
+	list_for_each_entry(reloc, &sec->reloc_list, list) {
+		switch (reloc->sym->type) {
+		case STT_FUNC:
+			func = reloc->sym;
+			break;
+
+		case STT_SECTION:
+			func = find_func_by_offset(reloc->sym->sec, reloc->addend);
+			if (!func)
+				continue;
+			break;
+
+		default:
+			WARN("unexpected relocation symbol type in %s: %d", sec->name, reloc->sym->type);
+			continue;
+		}
+
+		func_for_each_insn(file, func, insn)
+			insn->ignore = true;
+	}
+}
+
+/*
+ * This is a whitelist of functions that is allowed to be called with AC set.
+ * The list is meant to be minimal and only contains compiler instrumentation
+ * ABI and a few functions used to implement *_{to,from}_user() functions.
+ *
+ * These functions must not directly change AC, but may PUSHF/POPF.
+ */
+static const char *uaccess_safe_builtin[] = {
+	/* KASAN */
+	"kasan_report",
+	"check_memory_region",
+	/* KASAN out-of-line */
+	"__asan_loadN_noabort",
+	"__asan_load1_noabort",
+	"__asan_load2_noabort",
+	"__asan_load4_noabort",
+	"__asan_load8_noabort",
+	"__asan_load16_noabort",
+	"__asan_storeN_noabort",
+	"__asan_store1_noabort",
+	"__asan_store2_noabort",
+	"__asan_store4_noabort",
+	"__asan_store8_noabort",
+	"__asan_store16_noabort",
+	"__kasan_check_read",
+	"__kasan_check_write",
+	/* KASAN in-line */
+	"__asan_report_load_n_noabort",
+	"__asan_report_load1_noabort",
+	"__asan_report_load2_noabort",
+	"__asan_report_load4_noabort",
+	"__asan_report_load8_noabort",
+	"__asan_report_load16_noabort",
+	"__asan_report_store_n_noabort",
+	"__asan_report_store1_noabort",
+	"__asan_report_store2_noabort",
+	"__asan_report_store4_noabort",
+	"__asan_report_store8_noabort",
+	"__asan_report_store16_noabort",
+	/* KCSAN */
+	"__kcsan_check_access",
+	"kcsan_found_watchpoint",
+	"kcsan_setup_watchpoint",
+	"kcsan_check_scoped_accesses",
+	"kcsan_disable_current",
+	"kcsan_enable_current_nowarn",
+	/* KCSAN/TSAN */
+	"__tsan_func_entry",
+	"__tsan_func_exit",
+	"__tsan_read_range",
+	"__tsan_write_range",
+	"__tsan_read1",
+	"__tsan_read2",
+	"__tsan_read4",
+	"__tsan_read8",
+	"__tsan_read16",
+	"__tsan_write1",
+	"__tsan_write2",
+	"__tsan_write4",
+	"__tsan_write8",
+	"__tsan_write16",
+	"__tsan_read_write1",
+	"__tsan_read_write2",
+	"__tsan_read_write4",
+	"__tsan_read_write8",
+	"__tsan_read_write16",
+	"__tsan_volatile_read1",
+	"__tsan_volatile_read2",
+	"__tsan_volatile_read4",
+	"__tsan_volatile_read8",
+	"__tsan_volatile_read16",
+	"__tsan_volatile_write1",
+	"__tsan_volatile_write2",
+	"__tsan_volatile_write4",
+	"__tsan_volatile_write8",
+	"__tsan_volatile_write16",
+	"__tsan_atomic8_load",
+	"__tsan_atomic16_load",
+	"__tsan_atomic32_load",
+	"__tsan_atomic64_load",
+	"__tsan_atomic8_store",
+	"__tsan_atomic16_store",
+	"__tsan_atomic32_store",
+	"__tsan_atomic64_store",
+	"__tsan_atomic8_exchange",
+	"__tsan_atomic16_exchange",
+	"__tsan_atomic32_exchange",
+	"__tsan_atomic64_exchange",
+	"__tsan_atomic8_fetch_add",
+	"__tsan_atomic16_fetch_add",
+	"__tsan_atomic32_fetch_add",
+	"__tsan_atomic64_fetch_add",
+	"__tsan_atomic8_fetch_sub",
+	"__tsan_atomic16_fetch_sub",
+	"__tsan_atomic32_fetch_sub",
+	"__tsan_atomic64_fetch_sub",
+	"__tsan_atomic8_fetch_and",
+	"__tsan_atomic16_fetch_and",
+	"__tsan_atomic32_fetch_and",
+	"__tsan_atomic64_fetch_and",
+	"__tsan_atomic8_fetch_or",
+	"__tsan_atomic16_fetch_or",
+	"__tsan_atomic32_fetch_or",
+	"__tsan_atomic64_fetch_or",
+	"__tsan_atomic8_fetch_xor",
+	"__tsan_atomic16_fetch_xor",
+	"__tsan_atomic32_fetch_xor",
+	"__tsan_atomic64_fetch_xor",
+	"__tsan_atomic8_fetch_nand",
+	"__tsan_atomic16_fetch_nand",
+	"__tsan_atomic32_fetch_nand",
+	"__tsan_atomic64_fetch_nand",
+	"__tsan_atomic8_compare_exchange_strong",
+	"__tsan_atomic16_compare_exchange_strong",
+	"__tsan_atomic32_compare_exchange_strong",
+	"__tsan_atomic64_compare_exchange_strong",
+	"__tsan_atomic8_compare_exchange_weak",
+	"__tsan_atomic16_compare_exchange_weak",
+	"__tsan_atomic32_compare_exchange_weak",
+	"__tsan_atomic64_compare_exchange_weak",
+	"__tsan_atomic8_compare_exchange_val",
+	"__tsan_atomic16_compare_exchange_val",
+	"__tsan_atomic32_compare_exchange_val",
+	"__tsan_atomic64_compare_exchange_val",
+	"__tsan_atomic_thread_fence",
+	"__tsan_atomic_signal_fence",
+	"__tsan_unaligned_read16",
+	"__tsan_unaligned_write16",
+	/* KCOV */
+	"write_comp_data",
+	"check_kcov_mode",
+	"__sanitizer_cov_trace_pc",
+	"__sanitizer_cov_trace_const_cmp1",
+	"__sanitizer_cov_trace_const_cmp2",
+	"__sanitizer_cov_trace_const_cmp4",
+	"__sanitizer_cov_trace_const_cmp8",
+	"__sanitizer_cov_trace_cmp1",
+	"__sanitizer_cov_trace_cmp2",
+	"__sanitizer_cov_trace_cmp4",
+	"__sanitizer_cov_trace_cmp8",
+	"__sanitizer_cov_trace_switch",
+	/* UBSAN */
+	"ubsan_type_mismatch_common",
+	"__ubsan_handle_type_mismatch",
+	"__ubsan_handle_type_mismatch_v1",
+	"__ubsan_handle_shift_out_of_bounds",
+	/* misc */
+	"csum_partial_copy_generic",
+	"copy_mc_fragile",
+	"copy_mc_fragile_handle_tail",
+	"copy_mc_enhanced_fast_string",
+	"ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
+	NULL
+};
+
+static void add_uaccess_safe(struct objtool_file *file)
+{
+	struct symbol *func;
+	const char **name;
+
+	if (!uaccess)
+		return;
+
+	for (name = uaccess_safe_builtin; *name; name++) {
+		func = find_symbol_by_name(file->elf, *name);
+		if (!func)
+			continue;
+
+		func->uaccess_safe = true;
+	}
+}
+
+/*
+ * FIXME: For now, just ignore any alternatives which add retpolines.  This is
+ * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
+ * But it at least allows objtool to understand the control flow *around* the
+ * retpoline.
+ */
+static int add_ignore_alternatives(struct objtool_file *file)
+{
+	struct section *sec;
+	struct reloc *reloc;
+	struct instruction *insn;
+
+	sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");
+	if (!sec)
+		return 0;
+
+	list_for_each_entry(reloc, &sec->reloc_list, list) {
+		if (reloc->sym->type != STT_SECTION) {
+			WARN("unexpected relocation symbol type in %s", sec->name);
+			return -1;
+		}
+
+		insn = find_insn(file, reloc->sym->sec, reloc->addend);
+		if (!insn) {
+			WARN("bad .discard.ignore_alts entry");
+			return -1;
+		}
+
+		insn->ignore_alts = true;
+	}
+
+	return 0;
+}
+
+/*
+ * Symbols that replace INSN_CALL_DYNAMIC, every (tail) call to such a symbol
+ * will be added to the .retpoline_sites section.
+ */
+__weak bool arch_is_retpoline(struct symbol *sym)
+{
+	return false;
+}
+
+/*
+ * Symbols that replace INSN_RETURN, every (tail) call to such a symbol
+ * will be added to the .return_sites section.
+ */
+__weak bool arch_is_rethunk(struct symbol *sym)
+{
+	return false;
+}
+
+/*
+ * Symbols that are embedded inside other instructions, because sometimes crazy
+ * code exists. These are mostly ignored for validation purposes.
+ */
+__weak bool arch_is_embedded_insn(struct symbol *sym)
+{
+	return false;
+}
+
+#define NEGATIVE_RELOC	((void *)-1L)
+
+static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
+{
+	if (insn->reloc == NEGATIVE_RELOC)
+		return NULL;
+
+	if (!insn->reloc) {
+		insn->reloc = find_reloc_by_dest_range(file->elf, insn->sec,
+						       insn->offset, insn->len);
+		if (!insn->reloc) {
+			insn->reloc = NEGATIVE_RELOC;
+			return NULL;
+		}
+	}
+
+	return insn->reloc;
+}
+
+static void remove_insn_ops(struct instruction *insn)
+{
+	struct stack_op *op, *tmp;
+
+	list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) {
+		list_del(&op->list);
+		free(op);
+	}
+}
+
+static void annotate_call_site(struct objtool_file *file,
+			       struct instruction *insn, bool sibling)
+{
+	struct reloc *reloc = insn_reloc(file, insn);
+	struct symbol *sym = insn->call_dest;
+
+	if (!sym)
+		sym = reloc->sym;
+
+	/*
+	 * Alternative replacement code is just template code which is
+	 * sometimes copied to the original instruction. For now, don't
+	 * annotate it. (In the future we might consider annotating the
+	 * original instruction if/when it ever makes sense to do so.)
+	 */
+	if (!strcmp(insn->sec->name, ".altinstr_replacement"))
+		return;
+
+	if (sym->static_call_tramp) {
+		list_add_tail(&insn->call_node, &file->static_call_list);
+		return;
+	}
+
+	if (sym->retpoline_thunk) {
+		list_add_tail(&insn->call_node, &file->retpoline_call_list);
+		return;
+	}
+
+	/*
+	 * Many compilers cannot disable KCOV with a function attribute
+	 * so they need a little help, NOP out any KCOV calls from noinstr
+	 * text.
+	 */
+	if (insn->sec->noinstr && sym->kcov) {
+		if (reloc) {
+			reloc->type = R_NONE;
+			elf_write_reloc(file->elf, reloc);
+		}
+
+		elf_write_insn(file->elf, insn->sec,
+			       insn->offset, insn->len,
+			       sibling ? arch_ret_insn(insn->len)
+			               : arch_nop_insn(insn->len));
+
+		insn->type = sibling ? INSN_RETURN : INSN_NOP;
+
+		if (sibling) {
+			/*
+			 * We've replaced the tail-call JMP insn by two new
+			 * insn: RET; INT3, except we only have a single struct
+			 * insn here. Mark it retpoline_safe to avoid the SLS
+			 * warning, instead of adding another insn.
+			 */
+			insn->retpoline_safe = true;
+		}
+
+		return;
+	}
+}
+
+static void add_call_dest(struct objtool_file *file, struct instruction *insn,
+			  struct symbol *dest, bool sibling)
+{
+	insn->call_dest = dest;
+	if (!dest)
+		return;
+
+	/*
+	 * Whatever stack impact regular CALLs have, should be undone
+	 * by the RETURN of the called function.
+	 *
+	 * Annotated intra-function calls retain the stack_ops but
+	 * are converted to JUMP, see read_intra_function_calls().
+	 */
+	remove_insn_ops(insn);
+
+	annotate_call_site(file, insn, sibling);
+}
+
+static void add_retpoline_call(struct objtool_file *file, struct instruction *insn)
+{
+	/*
+	 * Retpoline calls/jumps are really dynamic calls/jumps in disguise,
+	 * so convert them accordingly.
+	 */
+	switch (insn->type) {
+	case INSN_CALL:
+		insn->type = INSN_CALL_DYNAMIC;
+		break;
+	case INSN_JUMP_UNCONDITIONAL:
+		insn->type = INSN_JUMP_DYNAMIC;
+		break;
+	case INSN_JUMP_CONDITIONAL:
+		insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
+		break;
+	default:
+		return;
+	}
+
+	insn->retpoline_safe = true;
+
+	/*
+	 * Whatever stack impact regular CALLs have, should be undone
+	 * by the RETURN of the called function.
+	 *
+	 * Annotated intra-function calls retain the stack_ops but
+	 * are converted to JUMP, see read_intra_function_calls().
+	 */
+	remove_insn_ops(insn);
+
+	annotate_call_site(file, insn, false);
+}
+
+static void add_return_call(struct objtool_file *file, struct instruction *insn, bool add)
+{
+	/*
+	 * Return thunk tail calls are really just returns in disguise,
+	 * so convert them accordingly.
+	 */
+	insn->type = INSN_RETURN;
+	insn->retpoline_safe = true;
+
+	/* Skip the non-text sections, specially .discard ones */
+	if (add && insn->sec->text)
+		list_add_tail(&insn->call_node, &file->return_thunk_list);
+}
+
+/*
+ * Find the destination instructions for all jumps.
+ */
+static int add_jump_destinations(struct objtool_file *file)
+{
+	struct instruction *insn;
+	struct reloc *reloc;
+	struct section *dest_sec;
+	unsigned long dest_off;
+
+	for_each_insn(file, insn) {
+		if (!is_static_jump(insn))
+			continue;
+
+		reloc = insn_reloc(file, insn);
+		if (!reloc) {
+			dest_sec = insn->sec;
+			dest_off = arch_jump_destination(insn);
+		} else if (reloc->sym->type == STT_SECTION) {
+			dest_sec = reloc->sym->sec;
+			dest_off = arch_dest_reloc_offset(reloc->addend);
+		} else if (reloc->sym->retpoline_thunk) {
+			add_retpoline_call(file, insn);
+			continue;
+		} else if (reloc->sym->return_thunk) {
+			add_return_call(file, insn, true);
+			continue;
+		} else if (insn->func) {
+			/* internal or external sibling call (with reloc) */
+			add_call_dest(file, insn, reloc->sym, true);
+			continue;
+		} else if (reloc->sym->sec->idx) {
+			dest_sec = reloc->sym->sec;
+			dest_off = reloc->sym->sym.st_value +
+				   arch_dest_reloc_offset(reloc->addend);
+		} else {
+			/* non-func asm code jumping to another file */
+			continue;
+		}
+
+		insn->jump_dest = find_insn(file, dest_sec, dest_off);
+		if (!insn->jump_dest) {
+			struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);
+
+			/*
+			 * This is a special case where an alt instruction
+			 * jumps past the end of the section.  These are
+			 * handled later in handle_group_alt().
+			 */
+			if (!strcmp(insn->sec->name, ".altinstr_replacement"))
+				continue;
+
+			/*
+			 * This is a special case for retbleed_untrain_ret().
+			 * It jumps to __x86_return_thunk(), but objtool
+			 * can't find the thunk's starting RET
+			 * instruction, because the RET is also in the
+			 * middle of another instruction.  Objtool only
+			 * knows about the outer instruction.
+			 */
+			if (sym && sym->embedded_insn) {
+				add_return_call(file, insn, false);
+				continue;
+			}
+
+			WARN_FUNC("can't find jump dest instruction at %s+0x%lx",
+				  insn->sec, insn->offset, dest_sec->name,
+				  dest_off);
+			return -1;
+		}
+
+		/*
+		 * Cross-function jump.
+		 */
+		if (insn->func && insn->jump_dest->func &&
+		    insn->func != insn->jump_dest->func) {
+
+			/*
+			 * For GCC 8+, create parent/child links for any cold
+			 * subfunctions.  This is _mostly_ redundant with a
+			 * similar initialization in read_symbols().
+			 *
+			 * If a function has aliases, we want the *first* such
+			 * function in the symbol table to be the subfunction's
+			 * parent.  In that case we overwrite the
+			 * initialization done in read_symbols().
+			 *
+			 * However this code can't completely replace the
+			 * read_symbols() code because this doesn't detect the
+			 * case where the parent function's only reference to a
+			 * subfunction is through a jump table.
+			 */
+			if (!strstr(insn->func->name, ".cold") &&
+			    strstr(insn->jump_dest->func->name, ".cold")) {
+				insn->func->cfunc = insn->jump_dest->func;
+				insn->jump_dest->func->pfunc = insn->func;
+
+			} else if (insn->jump_dest->func->pfunc != insn->func->pfunc &&
+				   insn->jump_dest->offset == insn->jump_dest->func->offset) {
+				/* internal sibling call (without reloc) */
+				add_call_dest(file, insn, insn->jump_dest->func, true);
+			}
+		}
+	}
+
+	return 0;
+}
+
+static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
+{
+	struct symbol *call_dest;
+
+	call_dest = find_func_by_offset(sec, offset);
+	if (!call_dest)
+		call_dest = find_symbol_by_offset(sec, offset);
+
+	return call_dest;
+}
+
+/*
+ * Find the destination instructions for all calls.
+ */
+static int add_call_destinations(struct objtool_file *file)
+{
+	struct instruction *insn;
+	unsigned long dest_off;
+	struct symbol *dest;
+	struct reloc *reloc;
+
+	for_each_insn(file, insn) {
+		if (insn->type != INSN_CALL)
+			continue;
+
+		reloc = insn_reloc(file, insn);
+		if (!reloc) {
+			dest_off = arch_jump_destination(insn);
+			dest = find_call_destination(insn->sec, dest_off);
+
+			add_call_dest(file, insn, dest, false);
+
+			if (insn->ignore)
+				continue;
+
+			if (!insn->call_dest) {
+				WARN_FUNC("unannotated intra-function call", insn->sec, insn->offset);
+				return -1;
+			}
+
+			if (insn->func && insn->call_dest->type != STT_FUNC) {
+				WARN_FUNC("unsupported call to non-function",
+					  insn->sec, insn->offset);
+				return -1;
+			}
+
+		} else if (reloc->sym->type == STT_SECTION) {
+			dest_off = arch_dest_reloc_offset(reloc->addend);
+			dest = find_call_destination(reloc->sym->sec, dest_off);
+			if (!dest) {
+				WARN_FUNC("can't find call dest symbol at %s+0x%lx",
+					  insn->sec, insn->offset,
+					  reloc->sym->sec->name,
+					  dest_off);
+				return -1;
+			}
+
+			add_call_dest(file, insn, dest, false);
+
+		} else if (reloc->sym->retpoline_thunk) {
+			add_retpoline_call(file, insn);
+
+		} else
+			add_call_dest(file, insn, reloc->sym, false);
+	}
+
+	return 0;
+}
+
+/*
+ * The .alternatives section requires some extra special care over and above
+ * other special sections because alternatives are patched in place.
+ */
+static int handle_group_alt(struct objtool_file *file,
+			    struct special_alt *special_alt,
+			    struct instruction *orig_insn,
+			    struct instruction **new_insn)
+{
+	struct instruction *last_orig_insn, *last_new_insn = NULL, *insn, *nop = NULL;
+	struct alt_group *orig_alt_group, *new_alt_group;
+	unsigned long dest_off;
+
+
+	orig_alt_group = malloc(sizeof(*orig_alt_group));
+	if (!orig_alt_group) {
+		WARN("malloc failed");
+		return -1;
+	}
+	orig_alt_group->cfi = calloc(special_alt->orig_len,
+				     sizeof(struct cfi_state *));
+	if (!orig_alt_group->cfi) {
+		WARN("calloc failed");
+		return -1;
+	}
+
+	last_orig_insn = NULL;
+	insn = orig_insn;
+	sec_for_each_insn_from(file, insn) {
+		if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
+			break;
+
+		insn->alt_group = orig_alt_group;
+		last_orig_insn = insn;
+	}
+	orig_alt_group->orig_group = NULL;
+	orig_alt_group->first_insn = orig_insn;
+	orig_alt_group->last_insn = last_orig_insn;
+
+
+	new_alt_group = malloc(sizeof(*new_alt_group));
+	if (!new_alt_group) {
+		WARN("malloc failed");
+		return -1;
+	}
+
+	if (special_alt->new_len < special_alt->orig_len) {
+		/*
+		 * Insert a fake nop at the end to make the replacement
+		 * alt_group the same size as the original.  This is needed to
+		 * allow propagate_alt_cfi() to do its magic.  When the last
+		 * instruction affects the stack, the instruction after it (the
+		 * nop) will propagate the new state to the shared CFI array.
+		 */
+		nop = malloc(sizeof(*nop));
+		if (!nop) {
+			WARN("malloc failed");
+			return -1;
+		}
+		memset(nop, 0, sizeof(*nop));
+		INIT_LIST_HEAD(&nop->alts);
+		INIT_LIST_HEAD(&nop->stack_ops);
+
+		nop->sec = special_alt->new_sec;
+		nop->offset = special_alt->new_off + special_alt->new_len;
+		nop->len = special_alt->orig_len - special_alt->new_len;
+		nop->type = INSN_NOP;
+		nop->func = orig_insn->func;
+		nop->alt_group = new_alt_group;
+		nop->ignore = orig_insn->ignore_alts;
+	}
+
+	if (!special_alt->new_len) {
+		*new_insn = nop;
+		goto end;
+	}
+
+	insn = *new_insn;
+	sec_for_each_insn_from(file, insn) {
+		struct reloc *alt_reloc;
+
+		if (insn->offset >= special_alt->new_off + special_alt->new_len)
+			break;
+
+		last_new_insn = insn;
+
+		insn->ignore = orig_insn->ignore_alts;
+		insn->func = orig_insn->func;
+		insn->alt_group = new_alt_group;
+
+		/*
+		 * Since alternative replacement code is copy/pasted by the
+		 * kernel after applying relocations, generally such code can't
+		 * have relative-address relocation references to outside the
+		 * .altinstr_replacement section, unless the arch's
+		 * alternatives code can adjust the relative offsets
+		 * accordingly.
+		 */
+		alt_reloc = insn_reloc(file, insn);
+		if (alt_reloc &&
+		    !arch_support_alt_relocation(special_alt, insn, alt_reloc)) {
+
+			WARN_FUNC("unsupported relocation in alternatives section",
+				  insn->sec, insn->offset);
+			return -1;
+		}
+
+		if (!is_static_jump(insn))
+			continue;
+
+		if (!insn->immediate)
+			continue;
+
+		dest_off = arch_jump_destination(insn);
+		if (dest_off == special_alt->new_off + special_alt->new_len)
+			insn->jump_dest = next_insn_same_sec(file, last_orig_insn);
+
+		if (!insn->jump_dest) {
+			WARN_FUNC("can't find alternative jump destination",
+				  insn->sec, insn->offset);
+			return -1;
+		}
+	}
+
+	if (!last_new_insn) {
+		WARN_FUNC("can't find last new alternative instruction",
+			  special_alt->new_sec, special_alt->new_off);
+		return -1;
+	}
+
+	if (nop)
+		list_add(&nop->list, &last_new_insn->list);
+end:
+	new_alt_group->orig_group = orig_alt_group;
+	new_alt_group->first_insn = *new_insn;
+	new_alt_group->last_insn = nop ? : last_new_insn;
+	new_alt_group->cfi = orig_alt_group->cfi;
+	return 0;
+}
+
+/*
+ * A jump table entry can either convert a nop to a jump or a jump to a nop.
+ * If the original instruction is a jump, make the alt entry an effective nop
+ * by just skipping the original instruction.
+ */
+static int handle_jump_alt(struct objtool_file *file,
+			   struct special_alt *special_alt,
+			   struct instruction *orig_insn,
+			   struct instruction **new_insn)
+{
+	if (orig_insn->type == INSN_NOP)
+		return 0;
+
+	if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) {
+		WARN_FUNC("unsupported instruction at jump label",
+			  orig_insn->sec, orig_insn->offset);
+		return -1;
+	}
+
+	*new_insn = list_next_entry(orig_insn, list);
+	return 0;
+}
+
+/*
+ * Read all the special sections which have alternate instructions which can be
+ * patched in or redirected to at runtime.  Each instruction having alternate
+ * instruction(s) has them added to its insn->alts list, which will be
+ * traversed in validate_branch().
+ */
+static int add_special_section_alts(struct objtool_file *file)
+{
+	struct list_head special_alts;
+	struct instruction *orig_insn, *new_insn;
+	struct special_alt *special_alt, *tmp;
+	struct alternative *alt;
+	int ret;
+
+	ret = special_get_alts(file->elf, &special_alts);
+	if (ret)
+		return ret;
+
+	list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
+
+		orig_insn = find_insn(file, special_alt->orig_sec,
+				      special_alt->orig_off);
+		if (!orig_insn) {
+			WARN_FUNC("special: can't find orig instruction",
+				  special_alt->orig_sec, special_alt->orig_off);
+			ret = -1;
+			goto out;
+		}
+
+		new_insn = NULL;
+		if (!special_alt->group || special_alt->new_len) {
+			new_insn = find_insn(file, special_alt->new_sec,
+					     special_alt->new_off);
+			if (!new_insn) {
+				WARN_FUNC("special: can't find new instruction",
+					  special_alt->new_sec,
+					  special_alt->new_off);
+				ret = -1;
+				goto out;
+			}
+		}
+
+		if (special_alt->group) {
+			if (!special_alt->orig_len) {
+				WARN_FUNC("empty alternative entry",
+					  orig_insn->sec, orig_insn->offset);
+				continue;
+			}
+
+			ret = handle_group_alt(file, special_alt, orig_insn,
+					       &new_insn);
+			if (ret)
+				goto out;
+		} else if (special_alt->jump_or_nop) {
+			ret = handle_jump_alt(file, special_alt, orig_insn,
+					      &new_insn);
+			if (ret)
+				goto out;
+		}
+
+		alt = malloc(sizeof(*alt));
+		if (!alt) {
+			WARN("malloc failed");
+			ret = -1;
+			goto out;
+		}
+
+		alt->insn = new_insn;
+		alt->skip_orig = special_alt->skip_orig;
+		orig_insn->ignore_alts |= special_alt->skip_alt;
+		list_add_tail(&alt->list, &orig_insn->alts);
+
+		list_del(&special_alt->list);
+		free(special_alt);
+	}
+
+out:
+	return ret;
+}
+
+static int add_jump_table(struct objtool_file *file, struct instruction *insn,
+			    struct reloc *table)
+{
+	struct reloc *reloc = table;
+	struct instruction *dest_insn;
+	struct alternative *alt;
+	struct symbol *pfunc = insn->func->pfunc;
+	unsigned int prev_offset = 0;
+
+	/*
+	 * Each @reloc is a switch table relocation which points to the target
+	 * instruction.
+	 */
+	list_for_each_entry_from(reloc, &table->sec->reloc_list, list) {
+
+		/* Check for the end of the table: */
+		if (reloc != table && reloc->jump_table_start)
+			break;
+
+		/* Make sure the table entries are consecutive: */
+		if (prev_offset && reloc->offset != prev_offset + 8)
+			break;
+
+		/* Detect function pointers from contiguous objects: */
+		if (reloc->sym->sec == pfunc->sec &&
+		    reloc->addend == pfunc->offset)
+			break;
+
+		dest_insn = find_insn(file, reloc->sym->sec, reloc->addend);
+		if (!dest_insn)
+			break;
+
+		/* Make sure the destination is in the same function: */
+		if (!dest_insn->func || dest_insn->func->pfunc != pfunc)
+			break;
+
+		alt = malloc(sizeof(*alt));
+		if (!alt) {
+			WARN("malloc failed");
+			return -1;
+		}
+
+		alt->insn = dest_insn;
+		list_add_tail(&alt->list, &insn->alts);
+		prev_offset = reloc->offset;
+	}
+
+	if (!prev_offset) {
+		WARN_FUNC("can't find switch jump table",
+			  insn->sec, insn->offset);
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * find_jump_table() - Given a dynamic jump, find the switch jump table
+ * associated with it.
+ */
+static struct reloc *find_jump_table(struct objtool_file *file,
+				      struct symbol *func,
+				      struct instruction *insn)
+{
+	struct reloc *table_reloc;
+	struct instruction *dest_insn, *orig_insn = insn;
+
+	/*
+	 * Backward search using the @first_jump_src links, these help avoid
+	 * much of the 'in between' code. Which avoids us getting confused by
+	 * it.
+	 */
+	for (;
+	     insn && insn->func && insn->func->pfunc == func;
+	     insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
+
+		if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
+			break;
+
+		/* allow small jumps within the range */
+		if (insn->type == INSN_JUMP_UNCONDITIONAL &&
+		    insn->jump_dest &&
+		    (insn->jump_dest->offset <= insn->offset ||
+		     insn->jump_dest->offset > orig_insn->offset))
+		    break;
+
+		table_reloc = arch_find_switch_table(file, insn);
+		if (!table_reloc)
+			continue;
+		dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend);
+		if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func)
+			continue;
+
+		return table_reloc;
+	}
+
+	return NULL;
+}
+
+/*
+ * First pass: Mark the head of each jump table so that in the next pass,
+ * we know when a given jump table ends and the next one starts.
+ */
+static void mark_func_jump_tables(struct objtool_file *file,
+				    struct symbol *func)
+{
+	struct instruction *insn, *last = NULL;
+	struct reloc *reloc;
+
+	func_for_each_insn(file, func, insn) {
+		if (!last)
+			last = insn;
+
+		/*
+		 * Store back-pointers for unconditional forward jumps such
+		 * that find_jump_table() can back-track using those and
+		 * avoid some potentially confusing code.
+		 */
+		if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
+		    insn->offset > last->offset &&
+		    insn->jump_dest->offset > insn->offset &&
+		    !insn->jump_dest->first_jump_src) {
+
+			insn->jump_dest->first_jump_src = insn;
+			last = insn->jump_dest;
+		}
+
+		if (insn->type != INSN_JUMP_DYNAMIC)
+			continue;
+
+		reloc = find_jump_table(file, func, insn);
+		if (reloc) {
+			reloc->jump_table_start = true;
+			insn->jump_table = reloc;
+		}
+	}
+}
+
+static int add_func_jump_tables(struct objtool_file *file,
+				  struct symbol *func)
+{
+	struct instruction *insn;
+	int ret;
+
+	func_for_each_insn(file, func, insn) {
+		if (!insn->jump_table)
+			continue;
+
+		ret = add_jump_table(file, insn, insn->jump_table);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * For some switch statements, gcc generates a jump table in the .rodata
+ * section which contains a list of addresses within the function to jump to.
+ * This finds these jump tables and adds them to the insn->alts lists.
+ */
+static int add_jump_table_alts(struct objtool_file *file)
+{
+	struct section *sec;
+	struct symbol *func;
+	int ret;
+
+	if (!file->rodata)
+		return 0;
+
+	for_each_sec(file, sec) {
+		list_for_each_entry(func, &sec->symbol_list, list) {
+			if (func->type != STT_FUNC)
+				continue;
+
+			mark_func_jump_tables(file, func);
+			ret = add_func_jump_tables(file, func);
+			if (ret)
+				return ret;
+		}
+	}
+
+	return 0;
+}
+
+static void set_func_state(struct cfi_state *state)
+{
+	state->cfa = initial_func_cfi.cfa;
+	memcpy(&state->regs, &initial_func_cfi.regs,
+	       CFI_NUM_REGS * sizeof(struct cfi_reg));
+	state->stack_size = initial_func_cfi.cfa.offset;
+}
+
+static int read_unwind_hints(struct objtool_file *file)
+{
+	struct cfi_state cfi = init_cfi;
+	struct section *sec, *relocsec;
+	struct unwind_hint *hint;
+	struct instruction *insn;
+	struct reloc *reloc;
+	int i;
+
+	sec = find_section_by_name(file->elf, ".discard.unwind_hints");
+	if (!sec)
+		return 0;
+
+	relocsec = sec->reloc;
+	if (!relocsec) {
+		WARN("missing .rela.discard.unwind_hints section");
+		return -1;
+	}
+
+	if (sec->len % sizeof(struct unwind_hint)) {
+		WARN("struct unwind_hint size mismatch");
+		return -1;
+	}
+
+	file->hints = true;
+
+	for (i = 0; i < sec->len / sizeof(struct unwind_hint); i++) {
+		hint = (struct unwind_hint *)sec->data->d_buf + i;
+
+		reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
+		if (!reloc) {
+			WARN("can't find reloc for unwind_hints[%d]", i);
+			return -1;
+		}
+
+		insn = find_insn(file, reloc->sym->sec, reloc->addend);
+		if (!insn) {
+			WARN("can't find insn for unwind_hints[%d]", i);
+			return -1;
+		}
+
+		insn->hint = true;
+
+		if (hint->type == UNWIND_HINT_TYPE_SAVE) {
+			insn->hint = false;
+			insn->save = true;
+			continue;
+		}
+
+		if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
+			insn->restore = true;
+			continue;
+		}
+
+		if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
+			struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);
+
+			if (sym && sym->bind == STB_GLOBAL) {
+				insn->entry = 1;
+			}
+		}
+
+		if (hint->type == UNWIND_HINT_TYPE_ENTRY) {
+			hint->type = UNWIND_HINT_TYPE_CALL;
+			insn->entry = 1;
+		}
+
+		if (hint->type == UNWIND_HINT_TYPE_FUNC) {
+			insn->cfi = &func_cfi;
+			continue;
+		}
+
+		if (insn->cfi)
+			cfi = *(insn->cfi);
+
+		if (arch_decode_hint_reg(hint->sp_reg, &cfi.cfa.base)) {
+			WARN_FUNC("unsupported unwind_hint sp base reg %d",
+				  insn->sec, insn->offset, hint->sp_reg);
+			return -1;
+		}
+
+		cfi.cfa.offset = hint->sp_offset;
+		cfi.type = hint->type;
+		cfi.end = hint->end;
+
+		insn->cfi = cfi_hash_find_or_add(&cfi);
+	}
+
+	return 0;
+}
+
+static int read_retpoline_hints(struct objtool_file *file)
+{
+	struct section *sec;
+	struct instruction *insn;
+	struct reloc *reloc;
+
+	sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
+	if (!sec)
+		return 0;
+
+	list_for_each_entry(reloc, &sec->reloc_list, list) {
+		if (reloc->sym->type != STT_SECTION) {
+			WARN("unexpected relocation symbol type in %s", sec->name);
+			return -1;
+		}
+
+		insn = find_insn(file, reloc->sym->sec, reloc->addend);
+		if (!insn) {
+			WARN("bad .discard.retpoline_safe entry");
+			return -1;
+		}
+
+		if (insn->type != INSN_JUMP_DYNAMIC &&
+		    insn->type != INSN_CALL_DYNAMIC &&
+		    insn->type != INSN_RETURN &&
+		    insn->type != INSN_NOP) {
+			WARN_FUNC("retpoline_safe hint not an indirect jump/call/ret/nop",
+				  insn->sec, insn->offset);
+			return -1;
+		}
+
+		insn->retpoline_safe = true;
+	}
+
+	return 0;
+}
+
+static int read_instr_hints(struct objtool_file *file)
+{
+	struct section *sec;
+	struct instruction *insn;
+	struct reloc *reloc;
+
+	sec = find_section_by_name(file->elf, ".rela.discard.instr_end");
+	if (!sec)
+		return 0;
+
+	list_for_each_entry(reloc, &sec->reloc_list, list) {
+		if (reloc->sym->type != STT_SECTION) {
+			WARN("unexpected relocation symbol type in %s", sec->name);
+			return -1;
+		}
+
+		insn = find_insn(file, reloc->sym->sec, reloc->addend);
+		if (!insn) {
+			WARN("bad .discard.instr_end entry");
+			return -1;
+		}
+
+		insn->instr--;
+	}
+
+	sec = find_section_by_name(file->elf, ".rela.discard.instr_begin");
+	if (!sec)
+		return 0;
+
+	list_for_each_entry(reloc, &sec->reloc_list, list) {
+		if (reloc->sym->type != STT_SECTION) {
+			WARN("unexpected relocation symbol type in %s", sec->name);
+			return -1;
+		}
+
+		insn = find_insn(file, reloc->sym->sec, reloc->addend);
+		if (!insn) {
+			WARN("bad .discard.instr_begin entry");
+			return -1;
+		}
+
+		insn->instr++;
+	}
+
+	return 0;
+}
+
+static int read_intra_function_calls(struct objtool_file *file)
+{
+	struct instruction *insn;
+	struct section *sec;
+	struct reloc *reloc;
+
+	sec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls");
+	if (!sec)
+		return 0;
+
+	list_for_each_entry(reloc, &sec->reloc_list, list) {
+		unsigned long dest_off;
+
+		if (reloc->sym->type != STT_SECTION) {
+			WARN("unexpected relocation symbol type in %s",
+			     sec->name);
+			return -1;
+		}
+
+		insn = find_insn(file, reloc->sym->sec, reloc->addend);
+		if (!insn) {
+			WARN("bad .discard.intra_function_call entry");
+			return -1;
+		}
+
+		if (insn->type != INSN_CALL) {
+			WARN_FUNC("intra_function_call not a direct call",
+				  insn->sec, insn->offset);
+			return -1;
+		}
+
+		/*
+		 * Treat intra-function CALLs as JMPs, but with a stack_op.
+		 * See add_call_destinations(), which strips stack_ops from
+		 * normal CALLs.
+		 */
+		insn->type = INSN_JUMP_UNCONDITIONAL;
+
+		dest_off = insn->offset + insn->len + insn->immediate;
+		insn->jump_dest = find_insn(file, insn->sec, dest_off);
+		if (!insn->jump_dest) {
+			WARN_FUNC("can't find call dest at %s+0x%lx",
+				  insn->sec, insn->offset,
+				  insn->sec->name, dest_off);
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+static int classify_symbols(struct objtool_file *file)
+{
+	struct section *sec;
+	struct symbol *func;
+
+	for_each_sec(file, sec) {
+		list_for_each_entry(func, &sec->symbol_list, list) {
+			if (func->bind != STB_GLOBAL)
+				continue;
+
+			if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
+				     strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
+				func->static_call_tramp = true;
+
+			if (arch_is_retpoline(func))
+				func->retpoline_thunk = true;
+
+			if (arch_is_rethunk(func))
+				func->return_thunk = true;
+
+			if (arch_is_embedded_insn(func))
+				func->embedded_insn = true;
+
+			if (!strcmp(func->name, "__fentry__"))
+				func->fentry = true;
+
+			if (!strncmp(func->name, "__sanitizer_cov_", 16))
+				func->kcov = true;
+		}
+	}
+
+	return 0;
+}
+
+static void mark_rodata(struct objtool_file *file)
+{
+	struct section *sec;
+	bool found = false;
+
+	/*
+	 * Search for the following rodata sections, each of which can
+	 * potentially contain jump tables:
+	 *
+	 * - .rodata: can contain GCC switch tables
+	 * - .rodata.<func>: same, if -fdata-sections is being used
+	 * - .rodata..c_jump_table: contains C annotated jump tables
+	 *
+	 * .rodata.str1.* sections are ignored; they don't contain jump tables.
+	 */
+	for_each_sec(file, sec) {
+		if (!strncmp(sec->name, ".rodata", 7) &&
+		    !strstr(sec->name, ".str1.")) {
+			sec->rodata = true;
+			found = true;
+		}
+	}
+
+	file->rodata = found;
+}
+
+static int decode_sections(struct objtool_file *file)
+{
+	int ret;
+
+	mark_rodata(file);
+
+	ret = decode_instructions(file);
+	if (ret)
+		return ret;
+
+	ret = add_dead_ends(file);
+	if (ret)
+		return ret;
+
+	add_ignores(file);
+	add_uaccess_safe(file);
+
+	ret = add_ignore_alternatives(file);
+	if (ret)
+		return ret;
+
+	/*
+	 * Must be before add_{jump_call}_destination.
+	 */
+	ret = classify_symbols(file);
+	if (ret)
+		return ret;
+
+	/*
+	 * Must be before add_special_section_alts() as that depends on
+	 * jump_dest being set.
+	 */
+	ret = add_jump_destinations(file);
+	if (ret)
+		return ret;
+
+	ret = add_special_section_alts(file);
+	if (ret)
+		return ret;
+
+	/*
+	 * Must be before add_call_destination(); it changes INSN_CALL to
+	 * INSN_JUMP.
+	 */
+	ret = read_intra_function_calls(file);
+	if (ret)
+		return ret;
+
+	ret = add_call_destinations(file);
+	if (ret)
+		return ret;
+
+	ret = add_jump_table_alts(file);
+	if (ret)
+		return ret;
+
+	ret = read_unwind_hints(file);
+	if (ret)
+		return ret;
+
+	ret = read_retpoline_hints(file);
+	if (ret)
+		return ret;
+
+	ret = read_instr_hints(file);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static bool is_special_call(struct instruction *insn)
+{
+	if (insn->type == INSN_CALL) {
+		struct symbol *dest = insn->call_dest;
+
+		if (!dest)
+			return false;
+
+		if (dest->fentry || dest->embedded_insn)
+			return true;
+	}
+
+	return false;
+}
+
+static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state)
+{
+	struct cfi_state *cfi = &state->cfi;
+	int i;
+
+	if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap)
+		return true;
+
+	if (cfi->cfa.offset != initial_func_cfi.cfa.offset)
+		return true;
+
+	if (cfi->stack_size != initial_func_cfi.cfa.offset)
+		return true;
+
+	for (i = 0; i < CFI_NUM_REGS; i++) {
+		if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
+		    cfi->regs[i].offset != initial_func_cfi.regs[i].offset)
+			return true;
+	}
+
+	return false;
+}
+
+static bool has_valid_stack_frame(struct insn_state *state)
+{
+	struct cfi_state *cfi = &state->cfi;
+
+	if (cfi->cfa.base == CFI_BP && cfi->regs[CFI_BP].base == CFI_CFA &&
+	    cfi->regs[CFI_BP].offset == -16)
+		return true;
+
+	if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP)
+		return true;
+
+	return false;
+}
+
+static int update_cfi_state_regs(struct instruction *insn,
+				  struct cfi_state *cfi,
+				  struct stack_op *op)
+{
+	struct cfi_reg *cfa = &cfi->cfa;
+
+	if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
+		return 0;
+
+	/* push */
+	if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF)
+		cfa->offset += 8;
+
+	/* pop */
+	if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF)
+		cfa->offset -= 8;
+
+	/* add immediate to sp */
+	if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
+	    op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
+		cfa->offset -= op->src.offset;
+
+	return 0;
+}
+
+static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset)
+{
+	if (arch_callee_saved_reg(reg) &&
+	    cfi->regs[reg].base == CFI_UNDEFINED) {
+		cfi->regs[reg].base = base;
+		cfi->regs[reg].offset = offset;
+	}
+}
+
+static void restore_reg(struct cfi_state *cfi, unsigned char reg)
+{
+	cfi->regs[reg].base = initial_func_cfi.regs[reg].base;
+	cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset;
+}
+
+/*
+ * A note about DRAP stack alignment:
+ *
+ * GCC has the concept of a DRAP register, which is used to help keep track of
+ * the stack pointer when aligning the stack.  r10 or r13 is used as the DRAP
+ * register.  The typical DRAP pattern is:
+ *
+ *   4c 8d 54 24 08		lea    0x8(%rsp),%r10
+ *   48 83 e4 c0		and    $0xffffffffffffffc0,%rsp
+ *   41 ff 72 f8		pushq  -0x8(%r10)
+ *   55				push   %rbp
+ *   48 89 e5			mov    %rsp,%rbp
+ *				(more pushes)
+ *   41 52			push   %r10
+ *				...
+ *   41 5a			pop    %r10
+ *				(more pops)
+ *   5d				pop    %rbp
+ *   49 8d 62 f8		lea    -0x8(%r10),%rsp
+ *   c3				retq
+ *
+ * There are some variations in the epilogues, like:
+ *
+ *   5b				pop    %rbx
+ *   41 5a			pop    %r10
+ *   41 5c			pop    %r12
+ *   41 5d			pop    %r13
+ *   41 5e			pop    %r14
+ *   c9				leaveq
+ *   49 8d 62 f8		lea    -0x8(%r10),%rsp
+ *   c3				retq
+ *
+ * and:
+ *
+ *   4c 8b 55 e8		mov    -0x18(%rbp),%r10
+ *   48 8b 5d e0		mov    -0x20(%rbp),%rbx
+ *   4c 8b 65 f0		mov    -0x10(%rbp),%r12
+ *   4c 8b 6d f8		mov    -0x8(%rbp),%r13
+ *   c9				leaveq
+ *   49 8d 62 f8		lea    -0x8(%r10),%rsp
+ *   c3				retq
+ *
+ * Sometimes r13 is used as the DRAP register, in which case it's saved and
+ * restored beforehand:
+ *
+ *   41 55			push   %r13
+ *   4c 8d 6c 24 10		lea    0x10(%rsp),%r13
+ *   48 83 e4 f0		and    $0xfffffffffffffff0,%rsp
+ *				...
+ *   49 8d 65 f0		lea    -0x10(%r13),%rsp
+ *   41 5d			pop    %r13
+ *   c3				retq
+ */
+static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi,
+			     struct stack_op *op)
+{
+	struct cfi_reg *cfa = &cfi->cfa;
+	struct cfi_reg *regs = cfi->regs;
+
+	/* stack operations don't make sense with an undefined CFA */
+	if (cfa->base == CFI_UNDEFINED) {
+		if (insn->func) {
+			WARN_FUNC("undefined stack state", insn->sec, insn->offset);
+			return -1;
+		}
+		return 0;
+	}
+
+	if (cfi->type == UNWIND_HINT_TYPE_REGS ||
+	    cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL)
+		return update_cfi_state_regs(insn, cfi, op);
+
+	switch (op->dest.type) {
+
+	case OP_DEST_REG:
+		switch (op->src.type) {
+
+		case OP_SRC_REG:
+			if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
+			    cfa->base == CFI_SP &&
+			    regs[CFI_BP].base == CFI_CFA &&
+			    regs[CFI_BP].offset == -cfa->offset) {
+
+				/* mov %rsp, %rbp */
+				cfa->base = op->dest.reg;
+				cfi->bp_scratch = false;
+			}
+
+			else if (op->src.reg == CFI_SP &&
+				 op->dest.reg == CFI_BP && cfi->drap) {
+
+				/* drap: mov %rsp, %rbp */
+				regs[CFI_BP].base = CFI_BP;
+				regs[CFI_BP].offset = -cfi->stack_size;
+				cfi->bp_scratch = false;
+			}
+
+			else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
+
+				/*
+				 * mov %rsp, %reg
+				 *
+				 * This is needed for the rare case where GCC
+				 * does:
+				 *
+				 *   mov    %rsp, %rax
+				 *   ...
+				 *   mov    %rax, %rsp
+				 */
+				cfi->vals[op->dest.reg].base = CFI_CFA;
+				cfi->vals[op->dest.reg].offset = -cfi->stack_size;
+			}
+
+			else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
+				 cfa->base == CFI_BP) {
+
+				/*
+				 * mov %rbp, %rsp
+				 *
+				 * Restore the original stack pointer (Clang).
+				 */
+				cfi->stack_size = -cfi->regs[CFI_BP].offset;
+			}
+
+			else if (op->dest.reg == cfa->base) {
+
+				/* mov %reg, %rsp */
+				if (cfa->base == CFI_SP &&
+				    cfi->vals[op->src.reg].base == CFI_CFA) {
+
+					/*
+					 * This is needed for the rare case
+					 * where GCC does something dumb like:
+					 *
+					 *   lea    0x8(%rsp), %rcx
+					 *   ...
+					 *   mov    %rcx, %rsp
+					 */
+					cfa->offset = -cfi->vals[op->src.reg].offset;
+					cfi->stack_size = cfa->offset;
+
+				} else {
+					cfa->base = CFI_UNDEFINED;
+					cfa->offset = 0;
+				}
+			}
+
+			break;
+
+		case OP_SRC_ADD:
+			if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
+
+				/* add imm, %rsp */
+				cfi->stack_size -= op->src.offset;
+				if (cfa->base == CFI_SP)
+					cfa->offset -= op->src.offset;
+				break;
+			}
+
+			if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
+
+				/* lea disp(%rbp), %rsp */
+				cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset);
+				break;
+			}
+
+			if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
+
+				/* drap: lea disp(%rsp), %drap */
+				cfi->drap_reg = op->dest.reg;
+
+				/*
+				 * lea disp(%rsp), %reg
+				 *
+				 * This is needed for the rare case where GCC
+				 * does something dumb like:
+				 *
+				 *   lea    0x8(%rsp), %rcx
+				 *   ...
+				 *   mov    %rcx, %rsp
+				 */
+				cfi->vals[op->dest.reg].base = CFI_CFA;
+				cfi->vals[op->dest.reg].offset = \
+					-cfi->stack_size + op->src.offset;
+
+				break;
+			}
+
+			if (cfi->drap && op->dest.reg == CFI_SP &&
+			    op->src.reg == cfi->drap_reg) {
+
+				 /* drap: lea disp(%drap), %rsp */
+				cfa->base = CFI_SP;
+				cfa->offset = cfi->stack_size = -op->src.offset;
+				cfi->drap_reg = CFI_UNDEFINED;
+				cfi->drap = false;
+				break;
+			}
+
+			if (op->dest.reg == cfi->cfa.base) {
+				WARN_FUNC("unsupported stack register modification",
+					  insn->sec, insn->offset);
+				return -1;
+			}
+
+			break;
+
+		case OP_SRC_AND:
+			if (op->dest.reg != CFI_SP ||
+			    (cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
+			    (cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
+				WARN_FUNC("unsupported stack pointer realignment",
+					  insn->sec, insn->offset);
+				return -1;
+			}
+
+			if (cfi->drap_reg != CFI_UNDEFINED) {
+				/* drap: and imm, %rsp */
+				cfa->base = cfi->drap_reg;
+				cfa->offset = cfi->stack_size = 0;
+				cfi->drap = true;
+			}
+
+			/*
+			 * Older versions of GCC (4.8ish) realign the stack
+			 * without DRAP, with a frame pointer.
+			 */
+
+			break;
+
+		case OP_SRC_POP:
+		case OP_SRC_POPF:
+			if (!cfi->drap && op->dest.reg == cfa->base) {
+
+				/* pop %rbp */
+				cfa->base = CFI_SP;
+			}
+
+			if (cfi->drap && cfa->base == CFI_BP_INDIRECT &&
+			    op->dest.reg == cfi->drap_reg &&
+			    cfi->drap_offset == -cfi->stack_size) {
+
+				/* drap: pop %drap */
+				cfa->base = cfi->drap_reg;
+				cfa->offset = 0;
+				cfi->drap_offset = -1;
+
+			} else if (regs[op->dest.reg].offset == -cfi->stack_size) {
+
+				/* pop %reg */
+				restore_reg(cfi, op->dest.reg);
+			}
+
+			cfi->stack_size -= 8;
+			if (cfa->base == CFI_SP)
+				cfa->offset -= 8;
+
+			break;
+
+		case OP_SRC_REG_INDIRECT:
+			if (cfi->drap && op->src.reg == CFI_BP &&
+			    op->src.offset == cfi->drap_offset) {
+
+				/* drap: mov disp(%rbp), %drap */
+				cfa->base = cfi->drap_reg;
+				cfa->offset = 0;
+				cfi->drap_offset = -1;
+			}
+
+			if (cfi->drap && op->src.reg == CFI_BP &&
+			    op->src.offset == regs[op->dest.reg].offset) {
+
+				/* drap: mov disp(%rbp), %reg */
+				restore_reg(cfi, op->dest.reg);
+
+			} else if (op->src.reg == cfa->base &&
+			    op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
+
+				/* mov disp(%rbp), %reg */
+				/* mov disp(%rsp), %reg */
+				restore_reg(cfi, op->dest.reg);
+			}
+
+			break;
+
+		default:
+			WARN_FUNC("unknown stack-related instruction",
+				  insn->sec, insn->offset);
+			return -1;
+		}
+
+		break;
+
+	case OP_DEST_PUSH:
+	case OP_DEST_PUSHF:
+		cfi->stack_size += 8;
+		if (cfa->base == CFI_SP)
+			cfa->offset += 8;
+
+		if (op->src.type != OP_SRC_REG)
+			break;
+
+		if (cfi->drap) {
+			if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
+
+				/* drap: push %drap */
+				cfa->base = CFI_BP_INDIRECT;
+				cfa->offset = -cfi->stack_size;
+
+				/* save drap so we know when to restore it */
+				cfi->drap_offset = -cfi->stack_size;
+
+			} else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) {
+
+				/* drap: push %rbp */
+				cfi->stack_size = 0;
+
+			} else {
+
+				/* drap: push %reg */
+				save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size);
+			}
+
+		} else {
+
+			/* push %reg */
+			save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size);
+		}
+
+		/* detect when asm code uses rbp as a scratch register */
+		if (!no_fp && insn->func && op->src.reg == CFI_BP &&
+		    cfa->base != CFI_BP)
+			cfi->bp_scratch = true;
+		break;
+
+	case OP_DEST_REG_INDIRECT:
+
+		if (cfi->drap) {
+			if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
+
+				/* drap: mov %drap, disp(%rbp) */
+				cfa->base = CFI_BP_INDIRECT;
+				cfa->offset = op->dest.offset;
+
+				/* save drap offset so we know when to restore it */
+				cfi->drap_offset = op->dest.offset;
+			} else {
+
+				/* drap: mov reg, disp(%rbp) */
+				save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset);
+			}
+
+		} else if (op->dest.reg == cfa->base) {
+
+			/* mov reg, disp(%rbp) */
+			/* mov reg, disp(%rsp) */
+			save_reg(cfi, op->src.reg, CFI_CFA,
+				 op->dest.offset - cfi->cfa.offset);
+		}
+
+		break;
+
+	case OP_DEST_LEAVE:
+		if ((!cfi->drap && cfa->base != CFI_BP) ||
+		    (cfi->drap && cfa->base != cfi->drap_reg)) {
+			WARN_FUNC("leave instruction with modified stack frame",
+				  insn->sec, insn->offset);
+			return -1;
+		}
+
+		/* leave (mov %rbp, %rsp; pop %rbp) */
+
+		cfi->stack_size = -cfi->regs[CFI_BP].offset - 8;
+		restore_reg(cfi, CFI_BP);
+
+		if (!cfi->drap) {
+			cfa->base = CFI_SP;
+			cfa->offset -= 8;
+		}
+
+		break;
+
+	case OP_DEST_MEM:
+		if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) {
+			WARN_FUNC("unknown stack-related memory operation",
+				  insn->sec, insn->offset);
+			return -1;
+		}
+
+		/* pop mem */
+		cfi->stack_size -= 8;
+		if (cfa->base == CFI_SP)
+			cfa->offset -= 8;
+
+		break;
+
+	default:
+		WARN_FUNC("unknown stack-related instruction",
+			  insn->sec, insn->offset);
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * The stack layouts of alternatives instructions can sometimes diverge when
+ * they have stack modifications.  That's fine as long as the potential stack
+ * layouts don't conflict at any given potential instruction boundary.
+ *
+ * Flatten the CFIs of the different alternative code streams (both original
+ * and replacement) into a single shared CFI array which can be used to detect
+ * conflicts and nicely feed a linear array of ORC entries to the unwinder.
+ */
+static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn)
+{
+	struct cfi_state **alt_cfi;
+	int group_off;
+
+	if (!insn->alt_group)
+		return 0;
+
+	if (!insn->cfi) {
+		WARN("CFI missing");
+		return -1;
+	}
+
+	alt_cfi = insn->alt_group->cfi;
+	group_off = insn->offset - insn->alt_group->first_insn->offset;
+
+	if (!alt_cfi[group_off]) {
+		alt_cfi[group_off] = insn->cfi;
+	} else {
+		if (cficmp(alt_cfi[group_off], insn->cfi)) {
+			WARN_FUNC("stack layout conflict in alternatives",
+				  insn->sec, insn->offset);
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+static int handle_insn_ops(struct instruction *insn, struct insn_state *state)
+{
+	struct stack_op *op;
+
+	list_for_each_entry(op, &insn->stack_ops, list) {
+
+		if (update_cfi_state(insn, &state->cfi, op))
+			return 1;
+
+		if (op->dest.type == OP_DEST_PUSHF) {
+			if (!state->uaccess_stack) {
+				state->uaccess_stack = 1;
+			} else if (state->uaccess_stack >> 31) {
+				WARN_FUNC("PUSHF stack exhausted",
+					  insn->sec, insn->offset);
+				return 1;
+			}
+			state->uaccess_stack <<= 1;
+			state->uaccess_stack  |= state->uaccess;
+		}
+
+		if (op->src.type == OP_SRC_POPF) {
+			if (state->uaccess_stack) {
+				state->uaccess = state->uaccess_stack & 1;
+				state->uaccess_stack >>= 1;
+				if (state->uaccess_stack == 1)
+					state->uaccess_stack = 0;
+			}
+		}
+	}
+
+	return 0;
+}
+
+static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2)
+{
+	struct cfi_state *cfi1 = insn->cfi;
+	int i;
+
+	if (!cfi1) {
+		WARN("CFI missing");
+		return false;
+	}
+
+	if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) {
+
+		WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
+			  insn->sec, insn->offset,
+			  cfi1->cfa.base, cfi1->cfa.offset,
+			  cfi2->cfa.base, cfi2->cfa.offset);
+
+	} else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) {
+		for (i = 0; i < CFI_NUM_REGS; i++) {
+			if (!memcmp(&cfi1->regs[i], &cfi2->regs[i],
+				    sizeof(struct cfi_reg)))
+				continue;
+
+			WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
+				  insn->sec, insn->offset,
+				  i, cfi1->regs[i].base, cfi1->regs[i].offset,
+				  i, cfi2->regs[i].base, cfi2->regs[i].offset);
+			break;
+		}
+
+	} else if (cfi1->type != cfi2->type) {
+
+		WARN_FUNC("stack state mismatch: type1=%d type2=%d",
+			  insn->sec, insn->offset, cfi1->type, cfi2->type);
+
+	} else if (cfi1->drap != cfi2->drap ||
+		   (cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) ||
+		   (cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) {
+
+		WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
+			  insn->sec, insn->offset,
+			  cfi1->drap, cfi1->drap_reg, cfi1->drap_offset,
+			  cfi2->drap, cfi2->drap_reg, cfi2->drap_offset);
+
+	} else
+		return true;
+
+	return false;
+}
+
+static inline bool func_uaccess_safe(struct symbol *func)
+{
+	if (func)
+		return func->uaccess_safe;
+
+	return false;
+}
+
+static inline const char *call_dest_name(struct instruction *insn)
+{
+	if (insn->call_dest)
+		return insn->call_dest->name;
+
+	return "{dynamic}";
+}
+
+static inline bool noinstr_call_dest(struct symbol *func)
+{
+	/*
+	 * We can't deal with indirect function calls at present;
+	 * assume they're instrumented.
+	 */
+	if (!func)
+		return false;
+
+	/*
+	 * If the symbol is from a noinstr section; we good.
+	 */
+	if (func->sec->noinstr)
+		return true;
+
+	/*
+	 * The __ubsan_handle_*() calls are like WARN(), they only happen when
+	 * something 'BAD' happened. At the risk of taking the machine down,
+	 * let them proceed to get the message out.
+	 */
+	if (!strncmp(func->name, "__ubsan_handle_", 15))
+		return true;
+
+	return false;
+}
+
+static int validate_call(struct instruction *insn, struct insn_state *state)
+{
+	if (state->noinstr && state->instr <= 0 &&
+	    !noinstr_call_dest(insn->call_dest)) {
+		WARN_FUNC("call to %s() leaves .noinstr.text section",
+				insn->sec, insn->offset, call_dest_name(insn));
+		return 1;
+	}
+
+	if (state->uaccess && !func_uaccess_safe(insn->call_dest)) {
+		WARN_FUNC("call to %s() with UACCESS enabled",
+				insn->sec, insn->offset, call_dest_name(insn));
+		return 1;
+	}
+
+	if (state->df) {
+		WARN_FUNC("call to %s() with DF set",
+				insn->sec, insn->offset, call_dest_name(insn));
+		return 1;
+	}
+
+	return 0;
+}
+
+static int validate_sibling_call(struct instruction *insn, struct insn_state *state)
+{
+	if (has_modified_stack_frame(insn, state)) {
+		WARN_FUNC("sibling call from callable instruction with modified stack frame",
+				insn->sec, insn->offset);
+		return 1;
+	}
+
+	return validate_call(insn, state);
+}
+
+static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state)
+{
+	if (state->noinstr && state->instr > 0) {
+		WARN_FUNC("return with instrumentation enabled",
+			  insn->sec, insn->offset);
+		return 1;
+	}
+
+	if (state->uaccess && !func_uaccess_safe(func)) {
+		WARN_FUNC("return with UACCESS enabled",
+			  insn->sec, insn->offset);
+		return 1;
+	}
+
+	if (!state->uaccess && func_uaccess_safe(func)) {
+		WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function",
+			  insn->sec, insn->offset);
+		return 1;
+	}
+
+	if (state->df) {
+		WARN_FUNC("return with DF set",
+			  insn->sec, insn->offset);
+		return 1;
+	}
+
+	if (func && has_modified_stack_frame(insn, state)) {
+		WARN_FUNC("return with modified stack frame",
+			  insn->sec, insn->offset);
+		return 1;
+	}
+
+	if (state->cfi.bp_scratch) {
+		WARN_FUNC("BP used as a scratch register",
+			  insn->sec, insn->offset);
+		return 1;
+	}
+
+	return 0;
+}
+
+static struct instruction *next_insn_to_validate(struct objtool_file *file,
+						 struct instruction *insn)
+{
+	struct alt_group *alt_group = insn->alt_group;
+
+	/*
+	 * Simulate the fact that alternatives are patched in-place.  When the
+	 * end of a replacement alt_group is reached, redirect objtool flow to
+	 * the end of the original alt_group.
+	 */
+	if (alt_group && insn == alt_group->last_insn && alt_group->orig_group)
+		return next_insn_same_sec(file, alt_group->orig_group->last_insn);
+
+	return next_insn_same_sec(file, insn);
+}
+
+/*
+ * Follow the branch starting at the given instruction, and recursively follow
+ * any other branches (jumps).  Meanwhile, track the frame pointer state at
+ * each instruction and validate all the rules described in
+ * tools/objtool/Documentation/stack-validation.txt.
+ */
+static int validate_branch(struct objtool_file *file, struct symbol *func,
+			   struct instruction *insn, struct insn_state state)
+{
+	struct alternative *alt;
+	struct instruction *next_insn, *prev_insn = NULL;
+	struct section *sec;
+	u8 visited;
+	int ret;
+
+	sec = insn->sec;
+
+	while (1) {
+		next_insn = next_insn_to_validate(file, insn);
+
+		if (file->c_file && func && insn->func && func != insn->func->pfunc) {
+			WARN("%s() falls through to next function %s()",
+			     func->name, insn->func->name);
+			return 1;
+		}
+
+		if (func && insn->ignore) {
+			WARN_FUNC("BUG: why am I validating an ignored function?",
+				  sec, insn->offset);
+			return 1;
+		}
+
+		visited = VISITED_BRANCH << state.uaccess;
+		if (insn->visited & VISITED_BRANCH_MASK) {
+			if (!insn->hint && !insn_cfi_match(insn, &state.cfi))
+				return 1;
+
+			if (insn->visited & visited)
+				return 0;
+		} else {
+			nr_insns_visited++;
+		}
+
+		if (state.noinstr)
+			state.instr += insn->instr;
+
+		if (insn->hint) {
+			if (insn->restore) {
+				struct instruction *save_insn, *i;
+
+				i = insn;
+				save_insn = NULL;
+
+				sym_for_each_insn_continue_reverse(file, func, i) {
+					if (i->save) {
+						save_insn = i;
+						break;
+					}
+				}
+
+				if (!save_insn) {
+					WARN_FUNC("no corresponding CFI save for CFI restore",
+						  sec, insn->offset);
+					return 1;
+				}
+
+				if (!save_insn->visited) {
+					WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo",
+						  sec, insn->offset);
+					return 1;
+				}
+
+				insn->cfi = save_insn->cfi;
+				nr_cfi_reused++;
+			}
+
+			state.cfi = *insn->cfi;
+		} else {
+			/* XXX track if we actually changed state.cfi */
+
+			if (prev_insn && !cficmp(prev_insn->cfi, &state.cfi)) {
+				insn->cfi = prev_insn->cfi;
+				nr_cfi_reused++;
+			} else {
+				insn->cfi = cfi_hash_find_or_add(&state.cfi);
+			}
+		}
+
+		insn->visited |= visited;
+
+		if (propagate_alt_cfi(file, insn))
+			return 1;
+
+		if (!insn->ignore_alts && !list_empty(&insn->alts)) {
+			bool skip_orig = false;
+
+			list_for_each_entry(alt, &insn->alts, list) {
+				if (alt->skip_orig)
+					skip_orig = true;
+
+				ret = validate_branch(file, func, alt->insn, state);
+				if (ret) {
+					if (backtrace)
+						BT_FUNC("(alt)", insn);
+					return ret;
+				}
+			}
+
+			if (skip_orig)
+				return 0;
+		}
+
+		if (handle_insn_ops(insn, &state))
+			return 1;
+
+		switch (insn->type) {
+
+		case INSN_RETURN:
+			if (sls && !insn->retpoline_safe &&
+			    next_insn && next_insn->type != INSN_TRAP) {
+				WARN_FUNC("missing int3 after ret",
+					  insn->sec, insn->offset);
+			}
+			return validate_return(func, insn, &state);
+
+		case INSN_CALL:
+		case INSN_CALL_DYNAMIC:
+			ret = validate_call(insn, &state);
+			if (ret)
+				return ret;
+
+			if (!no_fp && func && !is_special_call(insn) &&
+			    !has_valid_stack_frame(&state)) {
+				WARN_FUNC("call without frame pointer save/setup",
+					  sec, insn->offset);
+				return 1;
+			}
+
+			if (dead_end_function(file, insn->call_dest))
+				return 0;
+
+			break;
+
+		case INSN_JUMP_CONDITIONAL:
+		case INSN_JUMP_UNCONDITIONAL:
+			if (is_sibling_call(insn)) {
+				ret = validate_sibling_call(insn, &state);
+				if (ret)
+					return ret;
+
+			} else if (insn->jump_dest) {
+				ret = validate_branch(file, func,
+						      insn->jump_dest, state);
+				if (ret) {
+					if (backtrace)
+						BT_FUNC("(branch)", insn);
+					return ret;
+				}
+			}
+
+			if (insn->type == INSN_JUMP_UNCONDITIONAL)
+				return 0;
+
+			break;
+
+		case INSN_JUMP_DYNAMIC:
+			if (sls && !insn->retpoline_safe &&
+			    next_insn && next_insn->type != INSN_TRAP) {
+				WARN_FUNC("missing int3 after indirect jump",
+					  insn->sec, insn->offset);
+			}
+
+			/* fallthrough */
+		case INSN_JUMP_DYNAMIC_CONDITIONAL:
+			if (is_sibling_call(insn)) {
+				ret = validate_sibling_call(insn, &state);
+				if (ret)
+					return ret;
+			}
+
+			if (insn->type == INSN_JUMP_DYNAMIC)
+				return 0;
+
+			break;
+
+		case INSN_CONTEXT_SWITCH:
+			if (func && (!next_insn || !next_insn->hint)) {
+				WARN_FUNC("unsupported instruction in callable function",
+					  sec, insn->offset);
+				return 1;
+			}
+			return 0;
+
+		case INSN_STAC:
+			if (state.uaccess) {
+				WARN_FUNC("recursive UACCESS enable", sec, insn->offset);
+				return 1;
+			}
+
+			state.uaccess = true;
+			break;
+
+		case INSN_CLAC:
+			if (!state.uaccess && func) {
+				WARN_FUNC("redundant UACCESS disable", sec, insn->offset);
+				return 1;
+			}
+
+			if (func_uaccess_safe(func) && !state.uaccess_stack) {
+				WARN_FUNC("UACCESS-safe disables UACCESS", sec, insn->offset);
+				return 1;
+			}
+
+			state.uaccess = false;
+			break;
+
+		case INSN_STD:
+			if (state.df) {
+				WARN_FUNC("recursive STD", sec, insn->offset);
+				return 1;
+			}
+
+			state.df = true;
+			break;
+
+		case INSN_CLD:
+			if (!state.df && func) {
+				WARN_FUNC("redundant CLD", sec, insn->offset);
+				return 1;
+			}
+
+			state.df = false;
+			break;
+
+		default:
+			break;
+		}
+
+		if (insn->dead_end)
+			return 0;
+
+		if (!next_insn) {
+			if (state.cfi.cfa.base == CFI_UNDEFINED)
+				return 0;
+			WARN("%s: unexpected end of section", sec->name);
+			return 1;
+		}
+
+		prev_insn = insn;
+		insn = next_insn;
+	}
+
+	return 0;
+}
+
+static int validate_unwind_hints(struct objtool_file *file, struct section *sec)
+{
+	struct instruction *insn;
+	struct insn_state state;
+	int ret, warnings = 0;
+
+	if (!file->hints)
+		return 0;
+
+	init_insn_state(&state, sec);
+
+	if (sec) {
+		insn = find_insn(file, sec, 0);
+		if (!insn)
+			return 0;
+	} else {
+		insn = list_first_entry(&file->insn_list, typeof(*insn), list);
+	}
+
+	while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) {
+		if (insn->hint && !insn->visited) {
+			ret = validate_branch(file, insn->func, insn, state);
+			if (ret && backtrace)
+				BT_FUNC("<=== (hint)", insn);
+			warnings += ret;
+		}
+
+		insn = list_next_entry(insn, list);
+	}
+
+	return warnings;
+}
+
+/*
+ * Validate rethunk entry constraint: must untrain RET before the first RET.
+ *
+ * Follow every branch (intra-function) and ensure ANNOTATE_UNRET_END comes
+ * before an actual RET instruction.
+ */
+static int validate_entry(struct objtool_file *file, struct instruction *insn)
+{
+	struct instruction *next, *dest;
+	int ret, warnings = 0;
+
+	for (;;) {
+		next = next_insn_to_validate(file, insn);
+
+		if (insn->visited & VISITED_ENTRY)
+			return 0;
+
+		insn->visited |= VISITED_ENTRY;
+
+		if (!insn->ignore_alts && !list_empty(&insn->alts)) {
+			struct alternative *alt;
+			bool skip_orig = false;
+
+			list_for_each_entry(alt, &insn->alts, list) {
+				if (alt->skip_orig)
+					skip_orig = true;
+
+				ret = validate_entry(file, alt->insn);
+				if (ret) {
+				        if (backtrace)
+						BT_FUNC("(alt)", insn);
+					return ret;
+				}
+			}
+
+			if (skip_orig)
+				return 0;
+		}
+
+		switch (insn->type) {
+
+		case INSN_CALL_DYNAMIC:
+		case INSN_JUMP_DYNAMIC:
+		case INSN_JUMP_DYNAMIC_CONDITIONAL:
+			WARN_FUNC("early indirect call", insn->sec, insn->offset);
+			return 1;
+
+		case INSN_JUMP_UNCONDITIONAL:
+		case INSN_JUMP_CONDITIONAL:
+			if (!is_sibling_call(insn)) {
+				if (!insn->jump_dest) {
+					WARN_FUNC("unresolved jump target after linking?!?",
+						  insn->sec, insn->offset);
+					return -1;
+				}
+				ret = validate_entry(file, insn->jump_dest);
+				if (ret) {
+					if (backtrace) {
+						BT_FUNC("(branch%s)", insn,
+							insn->type == INSN_JUMP_CONDITIONAL ? "-cond" : "");
+					}
+					return ret;
+				}
+
+				if (insn->type == INSN_JUMP_UNCONDITIONAL)
+					return 0;
+
+				break;
+			}
+
+			/* fallthrough */
+		case INSN_CALL:
+			dest = find_insn(file, insn->call_dest->sec,
+					 insn->call_dest->offset);
+			if (!dest) {
+				WARN("Unresolved function after linking!?: %s",
+				     insn->call_dest->name);
+				return -1;
+			}
+
+			ret = validate_entry(file, dest);
+			if (ret) {
+				if (backtrace)
+					BT_FUNC("(call)", insn);
+				return ret;
+			}
+			/*
+			 * If a call returns without error, it must have seen UNTRAIN_RET.
+			 * Therefore any non-error return is a success.
+			 */
+			return 0;
+
+		case INSN_RETURN:
+			WARN_FUNC("RET before UNTRAIN", insn->sec, insn->offset);
+			return 1;
+
+		case INSN_NOP:
+			if (insn->retpoline_safe)
+				return 0;
+			break;
+
+		default:
+			break;
+		}
+
+		if (!next) {
+			WARN_FUNC("teh end!", insn->sec, insn->offset);
+			return -1;
+		}
+		insn = next;
+	}
+
+	return warnings;
+}
+
+/*
+ * Validate that all branches starting at 'insn->entry' encounter UNRET_END
+ * before RET.
+ */
+static int validate_unret(struct objtool_file *file)
+{
+	struct instruction *insn;
+	int ret, warnings = 0;
+
+	for_each_insn(file, insn) {
+		if (!insn->entry)
+			continue;
+
+		ret = validate_entry(file, insn);
+		if (ret < 0) {
+			WARN_FUNC("Failed UNRET validation", insn->sec, insn->offset);
+			return ret;
+		}
+		warnings += ret;
+	}
+
+	return warnings;
+}
+
+static int validate_retpoline(struct objtool_file *file)
+{
+	struct instruction *insn;
+	int warnings = 0;
+
+	for_each_insn(file, insn) {
+		if (insn->type != INSN_JUMP_DYNAMIC &&
+		    insn->type != INSN_CALL_DYNAMIC &&
+		    insn->type != INSN_RETURN)
+			continue;
+
+		if (insn->retpoline_safe)
+			continue;
+
+		/*
+		 * .init.text code is ran before userspace and thus doesn't
+		 * strictly need retpolines, except for modules which are
+		 * loaded late, they very much do need retpoline in their
+		 * .init.text
+		 */
+		if (!strcmp(insn->sec->name, ".init.text") && !module)
+			continue;
+
+		if (insn->type == INSN_RETURN) {
+			if (rethunk) {
+				WARN_FUNC("'naked' return found in RETHUNK build",
+					  insn->sec, insn->offset);
+			} else
+				continue;
+		} else {
+			WARN_FUNC("indirect %s found in RETPOLINE build",
+				  insn->sec, insn->offset,
+				  insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
+		}
+
+		warnings++;
+	}
+
+	return warnings;
+}
+
+static bool is_kasan_insn(struct instruction *insn)
+{
+	return (insn->type == INSN_CALL &&
+		!strcmp(insn->call_dest->name, "__asan_handle_no_return"));
+}
+
+static bool is_ubsan_insn(struct instruction *insn)
+{
+	return (insn->type == INSN_CALL &&
+		!strcmp(insn->call_dest->name,
+			"__ubsan_handle_builtin_unreachable"));
+}
+
+static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn)
+{
+	int i;
+	struct instruction *prev_insn;
+
+	if (insn->ignore || insn->type == INSN_NOP || insn->type == INSN_TRAP)
+		return true;
+
+	/*
+	 * Ignore any unused exceptions.  This can happen when a whitelisted
+	 * function has an exception table entry.
+	 *
+	 * Also ignore alternative replacement instructions.  This can happen
+	 * when a whitelisted function uses one of the ALTERNATIVE macros.
+	 */
+	if (!strcmp(insn->sec->name, ".fixup") ||
+	    !strcmp(insn->sec->name, ".altinstr_replacement") ||
+	    !strcmp(insn->sec->name, ".altinstr_aux"))
+		return true;
+
+	if (!insn->func)
+		return false;
+
+	/*
+	 * CONFIG_UBSAN_TRAP inserts a UD2 when it sees
+	 * __builtin_unreachable().  The BUG() macro has an unreachable() after
+	 * the UD2, which causes GCC's undefined trap logic to emit another UD2
+	 * (or occasionally a JMP to UD2).
+	 *
+	 * It may also insert a UD2 after calling a __noreturn function.
+	 */
+	prev_insn = list_prev_entry(insn, list);
+	if ((prev_insn->dead_end || dead_end_function(file, prev_insn->call_dest)) &&
+	    (insn->type == INSN_BUG ||
+	     (insn->type == INSN_JUMP_UNCONDITIONAL &&
+	      insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
+		return true;
+
+	/*
+	 * Check if this (or a subsequent) instruction is related to
+	 * CONFIG_UBSAN or CONFIG_KASAN.
+	 *
+	 * End the search at 5 instructions to avoid going into the weeds.
+	 */
+	for (i = 0; i < 5; i++) {
+
+		if (is_kasan_insn(insn) || is_ubsan_insn(insn))
+			return true;
+
+		if (insn->type == INSN_JUMP_UNCONDITIONAL) {
+			if (insn->jump_dest &&
+			    insn->jump_dest->func == insn->func) {
+				insn = insn->jump_dest;
+				continue;
+			}
+
+			break;
+		}
+
+		if (insn->offset + insn->len >= insn->func->offset + insn->func->len)
+			break;
+
+		insn = list_next_entry(insn, list);
+	}
+
+	return false;
+}
+
+static int validate_symbol(struct objtool_file *file, struct section *sec,
+			   struct symbol *sym, struct insn_state *state)
+{
+	struct instruction *insn;
+	int ret;
+
+	if (!sym->len) {
+		WARN("%s() is missing an ELF size annotation", sym->name);
+		return 1;
+	}
+
+	if (sym->pfunc != sym || sym->alias != sym)
+		return 0;
+
+	insn = find_insn(file, sec, sym->offset);
+	if (!insn || insn->ignore || insn->visited)
+		return 0;
+
+	state->uaccess = sym->uaccess_safe;
+
+	ret = validate_branch(file, insn->func, insn, *state);
+	if (ret && backtrace)
+		BT_FUNC("<=== (sym)", insn);
+	return ret;
+}
+
+static int validate_section(struct objtool_file *file, struct section *sec)
+{
+	struct insn_state state;
+	struct symbol *func;
+	int warnings = 0;
+
+	list_for_each_entry(func, &sec->symbol_list, list) {
+		if (func->type != STT_FUNC)
+			continue;
+
+		init_insn_state(&state, sec);
+		set_func_state(&state.cfi);
+
+		warnings += validate_symbol(file, sec, func, &state);
+	}
+
+	return warnings;
+}
+
+static int validate_vmlinux_functions(struct objtool_file *file)
+{
+	struct section *sec;
+	int warnings = 0;
+
+	sec = find_section_by_name(file->elf, ".noinstr.text");
+	if (sec) {
+		warnings += validate_section(file, sec);
+		warnings += validate_unwind_hints(file, sec);
+	}
+
+	sec = find_section_by_name(file->elf, ".entry.text");
+	if (sec) {
+		warnings += validate_section(file, sec);
+		warnings += validate_unwind_hints(file, sec);
+	}
+
+	return warnings;
+}
+
+static int validate_functions(struct objtool_file *file)
+{
+	struct section *sec;
+	int warnings = 0;
+
+	for_each_sec(file, sec) {
+		if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+			continue;
+
+		warnings += validate_section(file, sec);
+	}
+
+	return warnings;
+}
+
+static int validate_reachable_instructions(struct objtool_file *file)
+{
+	struct instruction *insn;
+
+	if (file->ignore_unreachables)
+		return 0;
+
+	for_each_insn(file, insn) {
+		if (insn->visited || ignore_unreachable_insn(file, insn))
+			continue;
+
+		WARN_FUNC("unreachable instruction", insn->sec, insn->offset);
+		return 1;
+	}
+
+	return 0;
+}
+
+int check(struct objtool_file *file)
+{
+	int ret, warnings = 0;
+
+	arch_initial_func_cfi_state(&initial_func_cfi);
+	init_cfi_state(&init_cfi);
+	init_cfi_state(&func_cfi);
+	set_func_state(&func_cfi);
+
+	if (!cfi_hash_alloc())
+		goto out;
+
+	cfi_hash_add(&init_cfi);
+	cfi_hash_add(&func_cfi);
+
+	ret = decode_sections(file);
+	if (ret < 0)
+		goto out;
+
+	warnings += ret;
+
+	if (list_empty(&file->insn_list))
+		goto out;
+
+	if (vmlinux && !validate_dup) {
+		ret = validate_vmlinux_functions(file);
+		if (ret < 0)
+			goto out;
+
+		warnings += ret;
+		goto out;
+	}
+
+	if (retpoline) {
+		ret = validate_retpoline(file);
+		if (ret < 0)
+			return ret;
+		warnings += ret;
+	}
+
+	ret = validate_functions(file);
+	if (ret < 0)
+		goto out;
+	warnings += ret;
+
+	ret = validate_unwind_hints(file, NULL);
+	if (ret < 0)
+		goto out;
+	warnings += ret;
+
+	if (unret) {
+		/*
+		 * Must be after validate_branch() and friends, it plays
+		 * further games with insn->visited.
+		 */
+		ret = validate_unret(file);
+		if (ret < 0)
+			return ret;
+		warnings += ret;
+	}
+
+	if (!warnings) {
+		ret = validate_reachable_instructions(file);
+		if (ret < 0)
+			goto out;
+		warnings += ret;
+	}
+
+	ret = create_static_call_sections(file);
+	if (ret < 0)
+		goto out;
+	warnings += ret;
+
+	if (retpoline) {
+		ret = create_retpoline_sites_sections(file);
+		if (ret < 0)
+			goto out;
+		warnings += ret;
+	}
+
+	if (rethunk) {
+		ret = create_return_sites_sections(file);
+		if (ret < 0)
+			goto out;
+		warnings += ret;
+	}
+
+	if (stats) {
+		printf("nr_insns_visited: %ld\n", nr_insns_visited);
+		printf("nr_cfi: %ld\n", nr_cfi);
+		printf("nr_cfi_reused: %ld\n", nr_cfi_reused);
+		printf("nr_cfi_cache: %ld\n", nr_cfi_cache);
+	}
+
+out:
+	/*
+	 *  For now, don't fail the kernel build on fatal warnings.  These
+	 *  errors are still fairly common due to the growing matrix of
+	 *  supported toolchains and their recent pace of change.
+	 */
+	return 0;
+}
diff --git a/tools/objtool/check.h b/tools/objtool/check.h
new file mode 100644
index 000000000..7f34a7f9c
--- /dev/null
+++ b/tools/objtool/check.h
@@ -0,0 +1,101 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#ifndef _CHECK_H
+#define _CHECK_H
+
+#include <stdbool.h>
+#include "cfi.h"
+#include "arch.h"
+
+struct insn_state {
+	struct cfi_state cfi;
+	unsigned int uaccess_stack;
+	bool uaccess;
+	bool df;
+	bool noinstr;
+	s8 instr;
+};
+
+struct alt_group {
+	/*
+	 * Pointer from a replacement group to the original group.  NULL if it
+	 * *is* the original group.
+	 */
+	struct alt_group *orig_group;
+
+	/* First and last instructions in the group */
+	struct instruction *first_insn, *last_insn;
+
+	/*
+	 * Byte-offset-addressed len-sized array of pointers to CFI structs.
+	 * This is shared with the other alt_groups in the same alternative.
+	 */
+	struct cfi_state **cfi;
+};
+
+struct instruction {
+	struct list_head list;
+	struct hlist_node hash;
+	struct list_head call_node;
+	struct section *sec;
+	unsigned long offset;
+	unsigned int len;
+	enum insn_type type;
+	unsigned long immediate;
+	bool dead_end, ignore, ignore_alts;
+	bool hint;
+	bool save, restore;
+	bool retpoline_safe;
+	bool entry;
+	s8 instr;
+	u8 visited;
+	struct alt_group *alt_group;
+	struct symbol *call_dest;
+	struct instruction *jump_dest;
+	struct instruction *first_jump_src;
+	struct reloc *jump_table;
+	struct reloc *reloc;
+	struct list_head alts;
+	struct symbol *func;
+	struct list_head stack_ops;
+	struct cfi_state *cfi;
+};
+
+#define VISITED_BRANCH		0x01
+#define VISITED_BRANCH_UACCESS	0x02
+#define VISITED_BRANCH_MASK	0x03
+#define VISITED_ENTRY		0x04
+
+static inline bool is_static_jump(struct instruction *insn)
+{
+	return insn->type == INSN_JUMP_CONDITIONAL ||
+	       insn->type == INSN_JUMP_UNCONDITIONAL;
+}
+
+static inline bool is_dynamic_jump(struct instruction *insn)
+{
+	return insn->type == INSN_JUMP_DYNAMIC ||
+	       insn->type == INSN_JUMP_DYNAMIC_CONDITIONAL;
+}
+
+static inline bool is_jump(struct instruction *insn)
+{
+	return is_static_jump(insn) || is_dynamic_jump(insn);
+}
+
+struct instruction *find_insn(struct objtool_file *file,
+			      struct section *sec, unsigned long offset);
+
+#define for_each_insn(file, insn)					\
+	list_for_each_entry(insn, &file->insn_list, list)
+
+#define sec_for_each_insn(file, sec, insn)				\
+	for (insn = find_insn(file, sec, 0);				\
+	     insn && &insn->list != &file->insn_list &&			\
+			insn->sec == sec;				\
+	     insn = list_next_entry(insn, list))
+
+#endif /* _CHECK_H */
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
new file mode 100644
index 000000000..a2ea3931e
--- /dev/null
+++ b/tools/objtool/elf.c
@@ -0,0 +1,1325 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * elf.c - ELF access library
+ *
+ * Adapted from kpatch (https://github.com/dynup/kpatch):
+ * Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com>
+ * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include "builtin.h"
+
+#include "elf.h"
+#include "warn.h"
+
+#define MAX_NAME_LEN 128
+
+static inline u32 str_hash(const char *str)
+{
+	return jhash(str, strlen(str), 0);
+}
+
+static inline int elf_hash_bits(void)
+{
+	return vmlinux ? ELF_HASH_BITS : 16;
+}
+
+#define elf_hash_add(hashtable, node, key) \
+	hlist_add_head(node, &hashtable[hash_min(key, elf_hash_bits())])
+
+static void elf_hash_init(struct hlist_head *table)
+{
+	__hash_init(table, 1U << elf_hash_bits());
+}
+
+#define elf_hash_for_each_possible(name, obj, member, key)			\
+	hlist_for_each_entry(obj, &name[hash_min(key, elf_hash_bits())], member)
+
+static void rb_add(struct rb_root *tree, struct rb_node *node,
+		   int (*cmp)(struct rb_node *, const struct rb_node *))
+{
+	struct rb_node **link = &tree->rb_node;
+	struct rb_node *parent = NULL;
+
+	while (*link) {
+		parent = *link;
+		if (cmp(node, parent) < 0)
+			link = &parent->rb_left;
+		else
+			link = &parent->rb_right;
+	}
+
+	rb_link_node(node, parent, link);
+	rb_insert_color(node, tree);
+}
+
+static struct rb_node *rb_find_first(const struct rb_root *tree, const void *key,
+			       int (*cmp)(const void *key, const struct rb_node *))
+{
+	struct rb_node *node = tree->rb_node;
+	struct rb_node *match = NULL;
+
+	while (node) {
+		int c = cmp(key, node);
+		if (c <= 0) {
+			if (!c)
+				match = node;
+			node = node->rb_left;
+		} else if (c > 0) {
+			node = node->rb_right;
+		}
+	}
+
+	return match;
+}
+
+static struct rb_node *rb_next_match(struct rb_node *node, const void *key,
+				    int (*cmp)(const void *key, const struct rb_node *))
+{
+	node = rb_next(node);
+	if (node && cmp(key, node))
+		node = NULL;
+	return node;
+}
+
+#define rb_for_each(tree, node, key, cmp) \
+	for ((node) = rb_find_first((tree), (key), (cmp)); \
+	     (node); (node) = rb_next_match((node), (key), (cmp)))
+
+static int symbol_to_offset(struct rb_node *a, const struct rb_node *b)
+{
+	struct symbol *sa = rb_entry(a, struct symbol, node);
+	struct symbol *sb = rb_entry(b, struct symbol, node);
+
+	if (sa->offset < sb->offset)
+		return -1;
+	if (sa->offset > sb->offset)
+		return 1;
+
+	if (sa->len < sb->len)
+		return -1;
+	if (sa->len > sb->len)
+		return 1;
+
+	sa->alias = sb;
+
+	return 0;
+}
+
+static int symbol_by_offset(const void *key, const struct rb_node *node)
+{
+	const struct symbol *s = rb_entry(node, struct symbol, node);
+	const unsigned long *o = key;
+
+	if (*o < s->offset)
+		return -1;
+	if (*o >= s->offset + s->len)
+		return 1;
+
+	return 0;
+}
+
+struct section *find_section_by_name(const struct elf *elf, const char *name)
+{
+	struct section *sec;
+
+	elf_hash_for_each_possible(elf->section_name_hash, sec, name_hash, str_hash(name))
+		if (!strcmp(sec->name, name))
+			return sec;
+
+	return NULL;
+}
+
+static struct section *find_section_by_index(struct elf *elf,
+					     unsigned int idx)
+{
+	struct section *sec;
+
+	elf_hash_for_each_possible(elf->section_hash, sec, hash, idx)
+		if (sec->idx == idx)
+			return sec;
+
+	return NULL;
+}
+
+static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
+{
+	struct symbol *sym;
+
+	elf_hash_for_each_possible(elf->symbol_hash, sym, hash, idx)
+		if (sym->idx == idx)
+			return sym;
+
+	return NULL;
+}
+
+struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
+{
+	struct rb_node *node;
+
+	rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
+		struct symbol *s = rb_entry(node, struct symbol, node);
+
+		if (s->offset == offset && s->type != STT_SECTION)
+			return s;
+	}
+
+	return NULL;
+}
+
+struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
+{
+	struct rb_node *node;
+
+	rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
+		struct symbol *s = rb_entry(node, struct symbol, node);
+
+		if (s->offset == offset && s->type == STT_FUNC)
+			return s;
+	}
+
+	return NULL;
+}
+
+struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset)
+{
+	struct rb_node *node;
+
+	rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
+		struct symbol *s = rb_entry(node, struct symbol, node);
+
+		if (s->type != STT_SECTION)
+			return s;
+	}
+
+	return NULL;
+}
+
+struct symbol *find_func_containing(struct section *sec, unsigned long offset)
+{
+	struct rb_node *node;
+
+	rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
+		struct symbol *s = rb_entry(node, struct symbol, node);
+
+		if (s->type == STT_FUNC)
+			return s;
+	}
+
+	return NULL;
+}
+
+struct symbol *find_symbol_by_name(const struct elf *elf, const char *name)
+{
+	struct symbol *sym;
+
+	elf_hash_for_each_possible(elf->symbol_name_hash, sym, name_hash, str_hash(name))
+		if (!strcmp(sym->name, name))
+			return sym;
+
+	return NULL;
+}
+
+struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
+				     unsigned long offset, unsigned int len)
+{
+	struct reloc *reloc, *r = NULL;
+	unsigned long o;
+
+	if (!sec->reloc)
+		return NULL;
+
+	sec = sec->reloc;
+
+	for_offset_range(o, offset, offset + len) {
+		elf_hash_for_each_possible(elf->reloc_hash, reloc, hash,
+				       sec_offset_hash(sec, o)) {
+			if (reloc->sec != sec)
+				continue;
+
+			if (reloc->offset >= offset && reloc->offset < offset + len) {
+				if (!r || reloc->offset < r->offset)
+					r = reloc;
+			}
+		}
+		if (r)
+			return r;
+	}
+
+	return NULL;
+}
+
+struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset)
+{
+	return find_reloc_by_dest_range(elf, sec, offset, 1);
+}
+
+static int read_sections(struct elf *elf)
+{
+	Elf_Scn *s = NULL;
+	struct section *sec;
+	size_t shstrndx, sections_nr;
+	int i;
+
+	if (elf_getshdrnum(elf->elf, &sections_nr)) {
+		WARN_ELF("elf_getshdrnum");
+		return -1;
+	}
+
+	if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
+		WARN_ELF("elf_getshdrstrndx");
+		return -1;
+	}
+
+	for (i = 0; i < sections_nr; i++) {
+		sec = malloc(sizeof(*sec));
+		if (!sec) {
+			perror("malloc");
+			return -1;
+		}
+		memset(sec, 0, sizeof(*sec));
+
+		INIT_LIST_HEAD(&sec->symbol_list);
+		INIT_LIST_HEAD(&sec->reloc_list);
+
+		s = elf_getscn(elf->elf, i);
+		if (!s) {
+			WARN_ELF("elf_getscn");
+			return -1;
+		}
+
+		sec->idx = elf_ndxscn(s);
+
+		if (!gelf_getshdr(s, &sec->sh)) {
+			WARN_ELF("gelf_getshdr");
+			return -1;
+		}
+
+		sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);
+		if (!sec->name) {
+			WARN_ELF("elf_strptr");
+			return -1;
+		}
+
+		if (sec->sh.sh_size != 0) {
+			sec->data = elf_getdata(s, NULL);
+			if (!sec->data) {
+				WARN_ELF("elf_getdata");
+				return -1;
+			}
+			if (sec->data->d_off != 0 ||
+			    sec->data->d_size != sec->sh.sh_size) {
+				WARN("unexpected data attributes for %s",
+				     sec->name);
+				return -1;
+			}
+		}
+		sec->len = sec->sh.sh_size;
+
+		list_add_tail(&sec->list, &elf->sections);
+		elf_hash_add(elf->section_hash, &sec->hash, sec->idx);
+		elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
+	}
+
+	if (stats)
+		printf("nr_sections: %lu\n", (unsigned long)sections_nr);
+
+	/* sanity check, one more call to elf_nextscn() should return NULL */
+	if (elf_nextscn(elf->elf, s)) {
+		WARN("section entry mismatch");
+		return -1;
+	}
+
+	return 0;
+}
+
+static void elf_add_symbol(struct elf *elf, struct symbol *sym)
+{
+	struct list_head *entry;
+	struct rb_node *pnode;
+
+	sym->alias = sym;
+
+	sym->type = GELF_ST_TYPE(sym->sym.st_info);
+	sym->bind = GELF_ST_BIND(sym->sym.st_info);
+
+	sym->offset = sym->sym.st_value;
+	sym->len = sym->sym.st_size;
+
+	rb_add(&sym->sec->symbol_tree, &sym->node, symbol_to_offset);
+	pnode = rb_prev(&sym->node);
+	if (pnode)
+		entry = &rb_entry(pnode, struct symbol, node)->list;
+	else
+		entry = &sym->sec->symbol_list;
+	list_add(&sym->list, entry);
+	elf_hash_add(elf->symbol_hash, &sym->hash, sym->idx);
+	elf_hash_add(elf->symbol_name_hash, &sym->name_hash, str_hash(sym->name));
+
+	/*
+	 * Don't store empty STT_NOTYPE symbols in the rbtree.  They
+	 * can exist within a function, confusing the sorting.
+	 */
+	if (!sym->len)
+		rb_erase(&sym->node, &sym->sec->symbol_tree);
+}
+
+static int read_symbols(struct elf *elf)
+{
+	struct section *symtab, *symtab_shndx, *sec;
+	struct symbol *sym, *pfunc;
+	int symbols_nr, i;
+	char *coldstr;
+	Elf_Data *shndx_data = NULL;
+	Elf32_Word shndx;
+
+	symtab = find_section_by_name(elf, ".symtab");
+	if (!symtab) {
+		/*
+		 * A missing symbol table is actually possible if it's an empty
+		 * .o file.  This can happen for thunk_64.o.
+		 */
+		return 0;
+	}
+
+	symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
+	if (symtab_shndx)
+		shndx_data = symtab_shndx->data;
+
+	symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
+
+	for (i = 0; i < symbols_nr; i++) {
+		sym = malloc(sizeof(*sym));
+		if (!sym) {
+			perror("malloc");
+			return -1;
+		}
+		memset(sym, 0, sizeof(*sym));
+
+		sym->idx = i;
+
+		if (!gelf_getsymshndx(symtab->data, shndx_data, i, &sym->sym,
+				      &shndx)) {
+			WARN_ELF("gelf_getsymshndx");
+			goto err;
+		}
+
+		sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
+				       sym->sym.st_name);
+		if (!sym->name) {
+			WARN_ELF("elf_strptr");
+			goto err;
+		}
+
+		if ((sym->sym.st_shndx > SHN_UNDEF &&
+		     sym->sym.st_shndx < SHN_LORESERVE) ||
+		    (shndx_data && sym->sym.st_shndx == SHN_XINDEX)) {
+			if (sym->sym.st_shndx != SHN_XINDEX)
+				shndx = sym->sym.st_shndx;
+
+			sym->sec = find_section_by_index(elf, shndx);
+			if (!sym->sec) {
+				WARN("couldn't find section for symbol %s",
+				     sym->name);
+				goto err;
+			}
+			if (GELF_ST_TYPE(sym->sym.st_info) == STT_SECTION) {
+				sym->name = sym->sec->name;
+				sym->sec->sym = sym;
+			}
+		} else
+			sym->sec = find_section_by_index(elf, 0);
+
+		elf_add_symbol(elf, sym);
+	}
+
+	if (stats)
+		printf("nr_symbols: %lu\n", (unsigned long)symbols_nr);
+
+	/* Create parent/child links for any cold subfunctions */
+	list_for_each_entry(sec, &elf->sections, list) {
+		list_for_each_entry(sym, &sec->symbol_list, list) {
+			char pname[MAX_NAME_LEN + 1];
+			size_t pnamelen;
+			if (sym->type != STT_FUNC)
+				continue;
+
+			if (sym->pfunc == NULL)
+				sym->pfunc = sym;
+
+			if (sym->cfunc == NULL)
+				sym->cfunc = sym;
+
+			coldstr = strstr(sym->name, ".cold");
+			if (!coldstr)
+				continue;
+
+			pnamelen = coldstr - sym->name;
+			if (pnamelen > MAX_NAME_LEN) {
+				WARN("%s(): parent function name exceeds maximum length of %d characters",
+				     sym->name, MAX_NAME_LEN);
+				return -1;
+			}
+
+			strncpy(pname, sym->name, pnamelen);
+			pname[pnamelen] = '\0';
+			pfunc = find_symbol_by_name(elf, pname);
+
+			if (!pfunc) {
+				WARN("%s(): can't find parent function",
+				     sym->name);
+				return -1;
+			}
+
+			sym->pfunc = pfunc;
+			pfunc->cfunc = sym;
+
+			/*
+			 * Unfortunately, -fnoreorder-functions puts the child
+			 * inside the parent.  Remove the overlap so we can
+			 * have sane assumptions.
+			 *
+			 * Note that pfunc->len now no longer matches
+			 * pfunc->sym.st_size.
+			 */
+			if (sym->sec == pfunc->sec &&
+			    sym->offset >= pfunc->offset &&
+			    sym->offset + sym->len == pfunc->offset + pfunc->len) {
+				pfunc->len -= sym->len;
+			}
+		}
+	}
+
+	return 0;
+
+err:
+	free(sym);
+	return -1;
+}
+
+static struct section *elf_create_reloc_section(struct elf *elf,
+						struct section *base,
+						int reltype);
+
+int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset,
+		  unsigned int type, struct symbol *sym, s64 addend)
+{
+	struct reloc *reloc;
+
+	if (!sec->reloc && !elf_create_reloc_section(elf, sec, SHT_RELA))
+		return -1;
+
+	reloc = malloc(sizeof(*reloc));
+	if (!reloc) {
+		perror("malloc");
+		return -1;
+	}
+	memset(reloc, 0, sizeof(*reloc));
+
+	reloc->sec = sec->reloc;
+	reloc->offset = offset;
+	reloc->type = type;
+	reloc->sym = sym;
+	reloc->addend = addend;
+
+	list_add_tail(&reloc->list, &sec->reloc->reloc_list);
+	elf_hash_add(elf->reloc_hash, &reloc->hash, reloc_hash(reloc));
+
+	sec->reloc->changed = true;
+
+	return 0;
+}
+
+/*
+ * Ensure that any reloc section containing references to @sym is marked
+ * changed such that it will get re-generated in elf_rebuild_reloc_sections()
+ * with the new symbol index.
+ */
+static void elf_dirty_reloc_sym(struct elf *elf, struct symbol *sym)
+{
+	struct section *sec;
+
+	list_for_each_entry(sec, &elf->sections, list) {
+		struct reloc *reloc;
+
+		if (sec->changed)
+			continue;
+
+		list_for_each_entry(reloc, &sec->reloc_list, list) {
+			if (reloc->sym == sym) {
+				sec->changed = true;
+				break;
+			}
+		}
+	}
+}
+
+/*
+ * The libelf API is terrible; gelf_update_sym*() takes a data block relative
+ * index value, *NOT* the symbol index. As such, iterate the data blocks and
+ * adjust index until it fits.
+ *
+ * If no data block is found, allow adding a new data block provided the index
+ * is only one past the end.
+ */
+static int elf_update_symbol(struct elf *elf, struct section *symtab,
+			     struct section *symtab_shndx, struct symbol *sym)
+{
+	Elf32_Word shndx = sym->sec ? sym->sec->idx : SHN_UNDEF;
+	Elf_Data *symtab_data = NULL, *shndx_data = NULL;
+	Elf64_Xword entsize = symtab->sh.sh_entsize;
+	int max_idx, idx = sym->idx;
+	Elf_Scn *s, *t = NULL;
+	bool is_special_shndx = sym->sym.st_shndx >= SHN_LORESERVE &&
+				sym->sym.st_shndx != SHN_XINDEX;
+
+	if (is_special_shndx)
+		shndx = sym->sym.st_shndx;
+
+	s = elf_getscn(elf->elf, symtab->idx);
+	if (!s) {
+		WARN_ELF("elf_getscn");
+		return -1;
+	}
+
+	if (symtab_shndx) {
+		t = elf_getscn(elf->elf, symtab_shndx->idx);
+		if (!t) {
+			WARN_ELF("elf_getscn");
+			return -1;
+		}
+	}
+
+	for (;;) {
+		/* get next data descriptor for the relevant sections */
+		symtab_data = elf_getdata(s, symtab_data);
+		if (t)
+			shndx_data = elf_getdata(t, shndx_data);
+
+		/* end-of-list */
+		if (!symtab_data) {
+			void *buf;
+
+			if (idx) {
+				/* we don't do holes in symbol tables */
+				WARN("index out of range");
+				return -1;
+			}
+
+			/* if @idx == 0, it's the next contiguous entry, create it */
+			symtab_data = elf_newdata(s);
+			if (t)
+				shndx_data = elf_newdata(t);
+
+			buf = calloc(1, entsize);
+			if (!buf) {
+				WARN("malloc");
+				return -1;
+			}
+
+			symtab_data->d_buf = buf;
+			symtab_data->d_size = entsize;
+			symtab_data->d_align = 1;
+			symtab_data->d_type = ELF_T_SYM;
+
+			symtab->sh.sh_size += entsize;
+			symtab->changed = true;
+
+			if (t) {
+				shndx_data->d_buf = &sym->sec->idx;
+				shndx_data->d_size = sizeof(Elf32_Word);
+				shndx_data->d_align = sizeof(Elf32_Word);
+				shndx_data->d_type = ELF_T_WORD;
+
+				symtab_shndx->sh.sh_size += sizeof(Elf32_Word);
+				symtab_shndx->changed = true;
+			}
+
+			break;
+		}
+
+		/* empty blocks should not happen */
+		if (!symtab_data->d_size) {
+			WARN("zero size data");
+			return -1;
+		}
+
+		/* is this the right block? */
+		max_idx = symtab_data->d_size / entsize;
+		if (idx < max_idx)
+			break;
+
+		/* adjust index and try again */
+		idx -= max_idx;
+	}
+
+	/* something went side-ways */
+	if (idx < 0) {
+		WARN("negative index");
+		return -1;
+	}
+
+	/* setup extended section index magic and write the symbol */
+	if ((shndx >= SHN_UNDEF && shndx < SHN_LORESERVE) || is_special_shndx) {
+		sym->sym.st_shndx = shndx;
+		if (!shndx_data)
+			shndx = 0;
+	} else {
+		sym->sym.st_shndx = SHN_XINDEX;
+		if (!shndx_data) {
+			WARN("no .symtab_shndx");
+			return -1;
+		}
+	}
+
+	if (!gelf_update_symshndx(symtab_data, shndx_data, idx, &sym->sym, shndx)) {
+		WARN_ELF("gelf_update_symshndx");
+		return -1;
+	}
+
+	return 0;
+}
+
+static struct symbol *
+elf_create_section_symbol(struct elf *elf, struct section *sec)
+{
+	struct section *symtab, *symtab_shndx;
+	Elf32_Word first_non_local, new_idx;
+	struct symbol *sym, *old;
+
+	symtab = find_section_by_name(elf, ".symtab");
+	if (symtab) {
+		symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
+	} else {
+		WARN("no .symtab");
+		return NULL;
+	}
+
+	sym = calloc(1, sizeof(*sym));
+	if (!sym) {
+		perror("malloc");
+		return NULL;
+	}
+
+	sym->name = sec->name;
+	sym->sec = sec;
+
+	// st_name 0
+	sym->sym.st_info = GELF_ST_INFO(STB_LOCAL, STT_SECTION);
+	// st_other 0
+	// st_value 0
+	// st_size 0
+
+	/*
+	 * Move the first global symbol, as per sh_info, into a new, higher
+	 * symbol index. This fees up a spot for a new local symbol.
+	 */
+	first_non_local = symtab->sh.sh_info;
+	new_idx = symtab->sh.sh_size / symtab->sh.sh_entsize;
+	old = find_symbol_by_index(elf, first_non_local);
+	if (old) {
+		old->idx = new_idx;
+
+		hlist_del(&old->hash);
+		elf_hash_add(elf->symbol_hash, &old->hash, old->idx);
+
+		elf_dirty_reloc_sym(elf, old);
+
+		if (elf_update_symbol(elf, symtab, symtab_shndx, old)) {
+			WARN("elf_update_symbol move");
+			return NULL;
+		}
+
+		new_idx = first_non_local;
+	}
+
+	sym->idx = new_idx;
+	if (elf_update_symbol(elf, symtab, symtab_shndx, sym)) {
+		WARN("elf_update_symbol");
+		return NULL;
+	}
+
+	/*
+	 * Either way, we added a LOCAL symbol.
+	 */
+	symtab->sh.sh_info += 1;
+
+	elf_add_symbol(elf, sym);
+
+	return sym;
+}
+
+int elf_add_reloc_to_insn(struct elf *elf, struct section *sec,
+			  unsigned long offset, unsigned int type,
+			  struct section *insn_sec, unsigned long insn_off)
+{
+	struct symbol *sym = insn_sec->sym;
+	int addend = insn_off;
+
+	if (!sym) {
+		/*
+		 * Due to how weak functions work, we must use section based
+		 * relocations. Symbol based relocations would result in the
+		 * weak and non-weak function annotations being overlaid on the
+		 * non-weak function after linking.
+		 */
+		sym = elf_create_section_symbol(elf, insn_sec);
+		if (!sym)
+			return -1;
+
+		insn_sec->sym = sym;
+	}
+
+	return elf_add_reloc(elf, sec, offset, type, sym, addend);
+}
+
+static int read_rel_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)
+{
+	if (!gelf_getrel(sec->data, i, &reloc->rel)) {
+		WARN_ELF("gelf_getrel");
+		return -1;
+	}
+	reloc->type = GELF_R_TYPE(reloc->rel.r_info);
+	reloc->addend = 0;
+	reloc->offset = reloc->rel.r_offset;
+	*symndx = GELF_R_SYM(reloc->rel.r_info);
+	return 0;
+}
+
+static int read_rela_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)
+{
+	if (!gelf_getrela(sec->data, i, &reloc->rela)) {
+		WARN_ELF("gelf_getrela");
+		return -1;
+	}
+	reloc->type = GELF_R_TYPE(reloc->rela.r_info);
+	reloc->addend = reloc->rela.r_addend;
+	reloc->offset = reloc->rela.r_offset;
+	*symndx = GELF_R_SYM(reloc->rela.r_info);
+	return 0;
+}
+
+static int read_relocs(struct elf *elf)
+{
+	struct section *sec;
+	struct reloc *reloc;
+	int i;
+	unsigned int symndx;
+	unsigned long nr_reloc, max_reloc = 0, tot_reloc = 0;
+
+	list_for_each_entry(sec, &elf->sections, list) {
+		if ((sec->sh.sh_type != SHT_RELA) &&
+		    (sec->sh.sh_type != SHT_REL))
+			continue;
+
+		sec->base = find_section_by_index(elf, sec->sh.sh_info);
+		if (!sec->base) {
+			WARN("can't find base section for reloc section %s",
+			     sec->name);
+			return -1;
+		}
+
+		sec->base->reloc = sec;
+
+		nr_reloc = 0;
+		for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
+			reloc = malloc(sizeof(*reloc));
+			if (!reloc) {
+				perror("malloc");
+				return -1;
+			}
+			memset(reloc, 0, sizeof(*reloc));
+			switch (sec->sh.sh_type) {
+			case SHT_REL:
+				if (read_rel_reloc(sec, i, reloc, &symndx))
+					return -1;
+				break;
+			case SHT_RELA:
+				if (read_rela_reloc(sec, i, reloc, &symndx))
+					return -1;
+				break;
+			default: return -1;
+			}
+
+			reloc->sec = sec;
+			reloc->idx = i;
+			reloc->sym = find_symbol_by_index(elf, symndx);
+			if (!reloc->sym) {
+				WARN("can't find reloc entry symbol %d for %s",
+				     symndx, sec->name);
+				return -1;
+			}
+
+			list_add_tail(&reloc->list, &sec->reloc_list);
+			elf_hash_add(elf->reloc_hash, &reloc->hash, reloc_hash(reloc));
+
+			nr_reloc++;
+		}
+		max_reloc = max(max_reloc, nr_reloc);
+		tot_reloc += nr_reloc;
+	}
+
+	if (stats) {
+		printf("max_reloc: %lu\n", max_reloc);
+		printf("tot_reloc: %lu\n", tot_reloc);
+	}
+
+	return 0;
+}
+
+struct elf *elf_open_read(const char *name, int flags)
+{
+	struct elf *elf;
+	Elf_Cmd cmd;
+
+	elf_version(EV_CURRENT);
+
+	elf = malloc(sizeof(*elf));
+	if (!elf) {
+		perror("malloc");
+		return NULL;
+	}
+	memset(elf, 0, offsetof(struct elf, sections));
+
+	INIT_LIST_HEAD(&elf->sections);
+
+	elf_hash_init(elf->symbol_hash);
+	elf_hash_init(elf->symbol_name_hash);
+	elf_hash_init(elf->section_hash);
+	elf_hash_init(elf->section_name_hash);
+	elf_hash_init(elf->reloc_hash);
+
+	elf->fd = open(name, flags);
+	if (elf->fd == -1) {
+		fprintf(stderr, "objtool: Can't open '%s': %s\n",
+			name, strerror(errno));
+		goto err;
+	}
+
+	if ((flags & O_ACCMODE) == O_RDONLY)
+		cmd = ELF_C_READ_MMAP;
+	else if ((flags & O_ACCMODE) == O_RDWR)
+		cmd = ELF_C_RDWR;
+	else /* O_WRONLY */
+		cmd = ELF_C_WRITE;
+
+	elf->elf = elf_begin(elf->fd, cmd, NULL);
+	if (!elf->elf) {
+		WARN_ELF("elf_begin");
+		goto err;
+	}
+
+	if (!gelf_getehdr(elf->elf, &elf->ehdr)) {
+		WARN_ELF("gelf_getehdr");
+		goto err;
+	}
+
+	if (read_sections(elf))
+		goto err;
+
+	if (read_symbols(elf))
+		goto err;
+
+	if (read_relocs(elf))
+		goto err;
+
+	return elf;
+
+err:
+	elf_close(elf);
+	return NULL;
+}
+
+static int elf_add_string(struct elf *elf, struct section *strtab, char *str)
+{
+	Elf_Data *data;
+	Elf_Scn *s;
+	int len;
+
+	if (!strtab)
+		strtab = find_section_by_name(elf, ".strtab");
+	if (!strtab) {
+		WARN("can't find .strtab section");
+		return -1;
+	}
+
+	s = elf_getscn(elf->elf, strtab->idx);
+	if (!s) {
+		WARN_ELF("elf_getscn");
+		return -1;
+	}
+
+	data = elf_newdata(s);
+	if (!data) {
+		WARN_ELF("elf_newdata");
+		return -1;
+	}
+
+	data->d_buf = str;
+	data->d_size = strlen(str) + 1;
+	data->d_align = 1;
+	data->d_type = ELF_T_SYM;
+
+	len = strtab->len;
+	strtab->len += data->d_size;
+	strtab->changed = true;
+
+	return len;
+}
+
+struct section *elf_create_section(struct elf *elf, const char *name,
+				   unsigned int sh_flags, size_t entsize, int nr)
+{
+	struct section *sec, *shstrtab;
+	size_t size = entsize * nr;
+	Elf_Scn *s;
+
+	sec = malloc(sizeof(*sec));
+	if (!sec) {
+		perror("malloc");
+		return NULL;
+	}
+	memset(sec, 0, sizeof(*sec));
+
+	INIT_LIST_HEAD(&sec->symbol_list);
+	INIT_LIST_HEAD(&sec->reloc_list);
+
+	s = elf_newscn(elf->elf);
+	if (!s) {
+		WARN_ELF("elf_newscn");
+		return NULL;
+	}
+
+	sec->name = strdup(name);
+	if (!sec->name) {
+		perror("strdup");
+		return NULL;
+	}
+
+	sec->idx = elf_ndxscn(s);
+	sec->len = size;
+	sec->changed = true;
+
+	sec->data = elf_newdata(s);
+	if (!sec->data) {
+		WARN_ELF("elf_newdata");
+		return NULL;
+	}
+
+	sec->data->d_size = size;
+	sec->data->d_align = 1;
+
+	if (size) {
+		sec->data->d_buf = malloc(size);
+		if (!sec->data->d_buf) {
+			perror("malloc");
+			return NULL;
+		}
+		memset(sec->data->d_buf, 0, size);
+	}
+
+	if (!gelf_getshdr(s, &sec->sh)) {
+		WARN_ELF("gelf_getshdr");
+		return NULL;
+	}
+
+	sec->sh.sh_size = size;
+	sec->sh.sh_entsize = entsize;
+	sec->sh.sh_type = SHT_PROGBITS;
+	sec->sh.sh_addralign = 1;
+	sec->sh.sh_flags = SHF_ALLOC | sh_flags;
+
+	/* Add section name to .shstrtab (or .strtab for Clang) */
+	shstrtab = find_section_by_name(elf, ".shstrtab");
+	if (!shstrtab)
+		shstrtab = find_section_by_name(elf, ".strtab");
+	if (!shstrtab) {
+		WARN("can't find .shstrtab or .strtab section");
+		return NULL;
+	}
+	sec->sh.sh_name = elf_add_string(elf, shstrtab, sec->name);
+	if (sec->sh.sh_name == -1)
+		return NULL;
+
+	list_add_tail(&sec->list, &elf->sections);
+	elf_hash_add(elf->section_hash, &sec->hash, sec->idx);
+	elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
+
+	elf->changed = true;
+
+	return sec;
+}
+
+static struct section *elf_create_rel_reloc_section(struct elf *elf, struct section *base)
+{
+	char *relocname;
+	struct section *sec;
+
+	relocname = malloc(strlen(base->name) + strlen(".rel") + 1);
+	if (!relocname) {
+		perror("malloc");
+		return NULL;
+	}
+	strcpy(relocname, ".rel");
+	strcat(relocname, base->name);
+
+	sec = elf_create_section(elf, relocname, 0, sizeof(GElf_Rel), 0);
+	free(relocname);
+	if (!sec)
+		return NULL;
+
+	base->reloc = sec;
+	sec->base = base;
+
+	sec->sh.sh_type = SHT_REL;
+	sec->sh.sh_addralign = 8;
+	sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
+	sec->sh.sh_info = base->idx;
+	sec->sh.sh_flags = SHF_INFO_LINK;
+
+	return sec;
+}
+
+static struct section *elf_create_rela_reloc_section(struct elf *elf, struct section *base)
+{
+	char *relocname;
+	struct section *sec;
+
+	relocname = malloc(strlen(base->name) + strlen(".rela") + 1);
+	if (!relocname) {
+		perror("malloc");
+		return NULL;
+	}
+	strcpy(relocname, ".rela");
+	strcat(relocname, base->name);
+
+	sec = elf_create_section(elf, relocname, 0, sizeof(GElf_Rela), 0);
+	free(relocname);
+	if (!sec)
+		return NULL;
+
+	base->reloc = sec;
+	sec->base = base;
+
+	sec->sh.sh_type = SHT_RELA;
+	sec->sh.sh_addralign = 8;
+	sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
+	sec->sh.sh_info = base->idx;
+	sec->sh.sh_flags = SHF_INFO_LINK;
+
+	return sec;
+}
+
+static struct section *elf_create_reloc_section(struct elf *elf,
+					 struct section *base,
+					 int reltype)
+{
+	switch (reltype) {
+	case SHT_REL:  return elf_create_rel_reloc_section(elf, base);
+	case SHT_RELA: return elf_create_rela_reloc_section(elf, base);
+	default:       return NULL;
+	}
+}
+
+static int elf_rebuild_rel_reloc_section(struct section *sec, int nr)
+{
+	struct reloc *reloc;
+	int idx = 0, size;
+	GElf_Rel *relocs;
+
+	/* Allocate a buffer for relocations */
+	size = nr * sizeof(*relocs);
+	relocs = malloc(size);
+	if (!relocs) {
+		perror("malloc");
+		return -1;
+	}
+
+	sec->data->d_buf = relocs;
+	sec->data->d_size = size;
+
+	sec->sh.sh_size = size;
+
+	idx = 0;
+	list_for_each_entry(reloc, &sec->reloc_list, list) {
+		relocs[idx].r_offset = reloc->offset;
+		relocs[idx].r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
+		idx++;
+	}
+
+	return 0;
+}
+
+static int elf_rebuild_rela_reloc_section(struct section *sec, int nr)
+{
+	struct reloc *reloc;
+	int idx = 0, size;
+	GElf_Rela *relocs;
+
+	/* Allocate a buffer for relocations with addends */
+	size = nr * sizeof(*relocs);
+	relocs = malloc(size);
+	if (!relocs) {
+		perror("malloc");
+		return -1;
+	}
+
+	sec->data->d_buf = relocs;
+	sec->data->d_size = size;
+
+	sec->sh.sh_size = size;
+
+	idx = 0;
+	list_for_each_entry(reloc, &sec->reloc_list, list) {
+		relocs[idx].r_offset = reloc->offset;
+		relocs[idx].r_addend = reloc->addend;
+		relocs[idx].r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
+		idx++;
+	}
+
+	return 0;
+}
+
+static int elf_rebuild_reloc_section(struct elf *elf, struct section *sec)
+{
+	struct reloc *reloc;
+	int nr;
+
+	nr = 0;
+	list_for_each_entry(reloc, &sec->reloc_list, list)
+		nr++;
+
+	switch (sec->sh.sh_type) {
+	case SHT_REL:  return elf_rebuild_rel_reloc_section(sec, nr);
+	case SHT_RELA: return elf_rebuild_rela_reloc_section(sec, nr);
+	default:       return -1;
+	}
+}
+
+int elf_write_insn(struct elf *elf, struct section *sec,
+		   unsigned long offset, unsigned int len,
+		   const char *insn)
+{
+	Elf_Data *data = sec->data;
+
+	if (data->d_type != ELF_T_BYTE || data->d_off) {
+		WARN("write to unexpected data for section: %s", sec->name);
+		return -1;
+	}
+
+	memcpy(data->d_buf + offset, insn, len);
+	elf_flagdata(data, ELF_C_SET, ELF_F_DIRTY);
+
+	elf->changed = true;
+
+	return 0;
+}
+
+int elf_write_reloc(struct elf *elf, struct reloc *reloc)
+{
+	struct section *sec = reloc->sec;
+
+	if (sec->sh.sh_type == SHT_REL) {
+		reloc->rel.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
+		reloc->rel.r_offset = reloc->offset;
+
+		if (!gelf_update_rel(sec->data, reloc->idx, &reloc->rel)) {
+			WARN_ELF("gelf_update_rel");
+			return -1;
+		}
+	} else {
+		reloc->rela.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
+		reloc->rela.r_addend = reloc->addend;
+		reloc->rela.r_offset = reloc->offset;
+
+		if (!gelf_update_rela(sec->data, reloc->idx, &reloc->rela)) {
+			WARN_ELF("gelf_update_rela");
+			return -1;
+		}
+	}
+
+	elf->changed = true;
+
+	return 0;
+}
+
+int elf_write(struct elf *elf)
+{
+	struct section *sec;
+	Elf_Scn *s;
+
+	/* Update changed relocation sections and section headers: */
+	list_for_each_entry(sec, &elf->sections, list) {
+		if (sec->changed) {
+			if (sec->base &&
+			    elf_rebuild_reloc_section(elf, sec)) {
+				WARN("elf_rebuild_reloc_section");
+				return -1;
+			}
+
+			s = elf_getscn(elf->elf, sec->idx);
+			if (!s) {
+				WARN_ELF("elf_getscn");
+				return -1;
+			}
+			if (!gelf_update_shdr(s, &sec->sh)) {
+				WARN_ELF("gelf_update_shdr");
+				return -1;
+			}
+
+			sec->changed = false;
+			elf->changed = true;
+		}
+	}
+
+	/* Make sure the new section header entries get updated properly. */
+	elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);
+
+	/* Write all changes to the file. */
+	if (elf_update(elf->elf, ELF_C_WRITE) < 0) {
+		WARN_ELF("elf_update");
+		return -1;
+	}
+
+	elf->changed = false;
+
+	return 0;
+}
+
+void elf_close(struct elf *elf)
+{
+	struct section *sec, *tmpsec;
+	struct symbol *sym, *tmpsym;
+	struct reloc *reloc, *tmpreloc;
+
+	if (elf->elf)
+		elf_end(elf->elf);
+
+	if (elf->fd > 0)
+		close(elf->fd);
+
+	list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) {
+		list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) {
+			list_del(&sym->list);
+			hash_del(&sym->hash);
+			free(sym);
+		}
+		list_for_each_entry_safe(reloc, tmpreloc, &sec->reloc_list, list) {
+			list_del(&reloc->list);
+			hash_del(&reloc->hash);
+			free(reloc);
+		}
+		list_del(&sec->list);
+		free(sec);
+	}
+
+	free(elf);
+}
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
new file mode 100644
index 000000000..19446d911
--- /dev/null
+++ b/tools/objtool/elf.h
@@ -0,0 +1,157 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#ifndef _OBJTOOL_ELF_H
+#define _OBJTOOL_ELF_H
+
+#include <stdio.h>
+#include <gelf.h>
+#include <linux/list.h>
+#include <linux/hashtable.h>
+#include <linux/rbtree.h>
+#include <linux/jhash.h>
+
+#ifdef LIBELF_USE_DEPRECATED
+# define elf_getshdrnum    elf_getshnum
+# define elf_getshdrstrndx elf_getshstrndx
+#endif
+
+/*
+ * Fallback for systems without this "read, mmaping if possible" cmd.
+ */
+#ifndef ELF_C_READ_MMAP
+#define ELF_C_READ_MMAP ELF_C_READ
+#endif
+
+struct section {
+	struct list_head list;
+	struct hlist_node hash;
+	struct hlist_node name_hash;
+	GElf_Shdr sh;
+	struct rb_root symbol_tree;
+	struct list_head symbol_list;
+	struct list_head reloc_list;
+	struct section *base, *reloc;
+	struct symbol *sym;
+	Elf_Data *data;
+	char *name;
+	int idx;
+	unsigned int len;
+	bool changed, text, rodata, noinstr;
+};
+
+struct symbol {
+	struct list_head list;
+	struct rb_node node;
+	struct hlist_node hash;
+	struct hlist_node name_hash;
+	GElf_Sym sym;
+	struct section *sec;
+	char *name;
+	unsigned int idx;
+	unsigned char bind, type;
+	unsigned long offset;
+	unsigned int len;
+	struct symbol *pfunc, *cfunc, *alias;
+	u8 uaccess_safe      : 1;
+	u8 static_call_tramp : 1;
+	u8 retpoline_thunk   : 1;
+	u8 return_thunk      : 1;
+	u8 fentry            : 1;
+	u8 kcov              : 1;
+	u8 embedded_insn     : 1;
+};
+
+struct reloc {
+	struct list_head list;
+	struct hlist_node hash;
+	union {
+		GElf_Rela rela;
+		GElf_Rel  rel;
+	};
+	struct section *sec;
+	struct symbol *sym;
+	unsigned long offset;
+	unsigned int type;
+	s64 addend;
+	int idx;
+	bool jump_table_start;
+};
+
+#define ELF_HASH_BITS	20
+
+struct elf {
+	Elf *elf;
+	GElf_Ehdr ehdr;
+	int fd;
+	bool changed;
+	char *name;
+	struct list_head sections;
+	DECLARE_HASHTABLE(symbol_hash, ELF_HASH_BITS);
+	DECLARE_HASHTABLE(symbol_name_hash, ELF_HASH_BITS);
+	DECLARE_HASHTABLE(section_hash, ELF_HASH_BITS);
+	DECLARE_HASHTABLE(section_name_hash, ELF_HASH_BITS);
+	DECLARE_HASHTABLE(reloc_hash, ELF_HASH_BITS);
+};
+
+#define OFFSET_STRIDE_BITS	4
+#define OFFSET_STRIDE		(1UL << OFFSET_STRIDE_BITS)
+#define OFFSET_STRIDE_MASK	(~(OFFSET_STRIDE - 1))
+
+#define for_offset_range(_offset, _start, _end)			\
+	for (_offset = ((_start) & OFFSET_STRIDE_MASK);		\
+	     _offset >= ((_start) & OFFSET_STRIDE_MASK) &&	\
+	     _offset <= ((_end) & OFFSET_STRIDE_MASK);		\
+	     _offset += OFFSET_STRIDE)
+
+static inline u32 sec_offset_hash(struct section *sec, unsigned long offset)
+{
+	u32 ol, oh, idx = sec->idx;
+
+	offset &= OFFSET_STRIDE_MASK;
+
+	ol = offset;
+	oh = (offset >> 16) >> 16;
+
+	__jhash_mix(ol, oh, idx);
+
+	return ol;
+}
+
+static inline u32 reloc_hash(struct reloc *reloc)
+{
+	return sec_offset_hash(reloc->sec, reloc->offset);
+}
+
+struct elf *elf_open_read(const char *name, int flags);
+struct section *elf_create_section(struct elf *elf, const char *name, unsigned int sh_flags, size_t entsize, int nr);
+
+int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset,
+		  unsigned int type, struct symbol *sym, s64 addend);
+int elf_add_reloc_to_insn(struct elf *elf, struct section *sec,
+			  unsigned long offset, unsigned int type,
+			  struct section *insn_sec, unsigned long insn_off);
+
+int elf_write_insn(struct elf *elf, struct section *sec,
+		   unsigned long offset, unsigned int len,
+		   const char *insn);
+int elf_write_reloc(struct elf *elf, struct reloc *reloc);
+int elf_write(struct elf *elf);
+void elf_close(struct elf *elf);
+
+struct section *find_section_by_name(const struct elf *elf, const char *name);
+struct symbol *find_func_by_offset(struct section *sec, unsigned long offset);
+struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset);
+struct symbol *find_symbol_by_name(const struct elf *elf, const char *name);
+struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset);
+struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset);
+struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
+				     unsigned long offset, unsigned int len);
+struct symbol *find_func_containing(struct section *sec, unsigned long offset);
+
+#define for_each_sec(file, sec)						\
+	list_for_each_entry(sec, &file->elf->sections, list)
+
+#endif /* _OBJTOOL_ELF_H */
diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c
new file mode 100644
index 000000000..cb2c6acd9
--- /dev/null
+++ b/tools/objtool/objtool.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+/*
+ * objtool:
+ *
+ * The 'check' subcmd analyzes every .o file and ensures the validity of its
+ * stack trace metadata.  It enforces a set of rules on asm code and C inline
+ * assembly code so that stack traces can be reliable.
+ *
+ * For more information, see tools/objtool/Documentation/stack-validation.txt.
+ */
+
+#include <stdio.h>
+#include <stdbool.h>
+#include <string.h>
+#include <stdlib.h>
+#include <subcmd/exec-cmd.h>
+#include <subcmd/pager.h>
+#include <linux/kernel.h>
+
+#include "builtin.h"
+#include "objtool.h"
+#include "warn.h"
+
+struct cmd_struct {
+	const char *name;
+	int (*fn)(int, const char **);
+	const char *help;
+};
+
+static const char objtool_usage_string[] =
+	"objtool COMMAND [ARGS]";
+
+static struct cmd_struct objtool_cmds[] = {
+	{"check",	cmd_check,	"Perform stack metadata validation on an object file" },
+	{"orc",		cmd_orc,	"Generate in-place ORC unwind tables for an object file" },
+};
+
+bool help;
+
+const char *objname;
+static struct objtool_file file;
+
+struct objtool_file *objtool_open_read(const char *_objname)
+{
+	if (objname) {
+		if (strcmp(objname, _objname)) {
+			WARN("won't handle more than one file at a time");
+			return NULL;
+		}
+		return &file;
+	}
+	objname = _objname;
+
+	file.elf = elf_open_read(objname, O_RDWR);
+	if (!file.elf)
+		return NULL;
+
+	INIT_LIST_HEAD(&file.insn_list);
+	hash_init(file.insn_hash);
+	INIT_LIST_HEAD(&file.retpoline_call_list);
+	INIT_LIST_HEAD(&file.return_thunk_list);
+	INIT_LIST_HEAD(&file.static_call_list);
+	file.c_file = !vmlinux && find_section_by_name(file.elf, ".comment");
+	file.ignore_unreachables = no_unreachable;
+	file.hints = false;
+
+	return &file;
+}
+
+static void cmd_usage(void)
+{
+	unsigned int i, longest = 0;
+
+	printf("\n usage: %s\n\n", objtool_usage_string);
+
+	for (i = 0; i < ARRAY_SIZE(objtool_cmds); i++) {
+		if (longest < strlen(objtool_cmds[i].name))
+			longest = strlen(objtool_cmds[i].name);
+	}
+
+	puts(" Commands:");
+	for (i = 0; i < ARRAY_SIZE(objtool_cmds); i++) {
+		printf("   %-*s   ", longest, objtool_cmds[i].name);
+		puts(objtool_cmds[i].help);
+	}
+
+	printf("\n");
+
+	if (!help)
+		exit(129);
+	exit(0);
+}
+
+static void handle_options(int *argc, const char ***argv)
+{
+	while (*argc > 0) {
+		const char *cmd = (*argv)[0];
+
+		if (cmd[0] != '-')
+			break;
+
+		if (!strcmp(cmd, "--help") || !strcmp(cmd, "-h")) {
+			help = true;
+			break;
+		} else {
+			fprintf(stderr, "Unknown option: %s\n", cmd);
+			cmd_usage();
+		}
+
+		(*argv)++;
+		(*argc)--;
+	}
+}
+
+static void handle_internal_command(int argc, const char **argv)
+{
+	const char *cmd = argv[0];
+	unsigned int i, ret;
+
+	for (i = 0; i < ARRAY_SIZE(objtool_cmds); i++) {
+		struct cmd_struct *p = objtool_cmds+i;
+
+		if (strcmp(p->name, cmd))
+			continue;
+
+		ret = p->fn(argc, argv);
+
+		exit(ret);
+	}
+
+	cmd_usage();
+}
+
+int main(int argc, const char **argv)
+{
+	static const char *UNUSED = "OBJTOOL_NOT_IMPLEMENTED";
+
+	/* libsubcmd init */
+	exec_cmd_init("objtool", UNUSED, UNUSED, UNUSED);
+	pager_init(UNUSED);
+
+	argv++;
+	argc--;
+	handle_options(&argc, &argv);
+
+	if (!argc || help)
+		cmd_usage();
+
+	handle_internal_command(argc, argv);
+
+	return 0;
+}
diff --git a/tools/objtool/objtool.h b/tools/objtool/objtool.h
new file mode 100644
index 000000000..bf64946e7
--- /dev/null
+++ b/tools/objtool/objtool.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2020 Matt Helsley <mhelsley@vmware.com>
+ */
+
+#ifndef _OBJTOOL_H
+#define _OBJTOOL_H
+
+#include <stdbool.h>
+#include <linux/list.h>
+#include <linux/hashtable.h>
+
+#include "elf.h"
+
+#define __weak __attribute__((weak))
+
+struct objtool_file {
+	struct elf *elf;
+	struct list_head insn_list;
+	DECLARE_HASHTABLE(insn_hash, 20);
+	struct list_head retpoline_call_list;
+	struct list_head return_thunk_list;
+	struct list_head static_call_list;
+	bool ignore_unreachables, c_file, hints, rodata;
+};
+
+struct objtool_file *objtool_open_read(const char *_objname);
+
+int check(struct objtool_file *file);
+int orc_dump(const char *objname);
+int orc_create(struct objtool_file *file);
+
+#endif /* _OBJTOOL_H */
diff --git a/tools/objtool/orc_dump.c b/tools/objtool/orc_dump.c
new file mode 100644
index 000000000..5e6a95368
--- /dev/null
+++ b/tools/objtool/orc_dump.c
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#include <unistd.h>
+#include <linux/objtool.h>
+#include <asm/orc_types.h>
+#include "objtool.h"
+#include "warn.h"
+
+static const char *reg_name(unsigned int reg)
+{
+	switch (reg) {
+	case ORC_REG_PREV_SP:
+		return "prevsp";
+	case ORC_REG_DX:
+		return "dx";
+	case ORC_REG_DI:
+		return "di";
+	case ORC_REG_BP:
+		return "bp";
+	case ORC_REG_SP:
+		return "sp";
+	case ORC_REG_R10:
+		return "r10";
+	case ORC_REG_R13:
+		return "r13";
+	case ORC_REG_BP_INDIRECT:
+		return "bp(ind)";
+	case ORC_REG_SP_INDIRECT:
+		return "sp(ind)";
+	default:
+		return "?";
+	}
+}
+
+static const char *orc_type_name(unsigned int type)
+{
+	switch (type) {
+	case UNWIND_HINT_TYPE_CALL:
+		return "call";
+	case UNWIND_HINT_TYPE_REGS:
+		return "regs";
+	case UNWIND_HINT_TYPE_REGS_PARTIAL:
+		return "regs (partial)";
+	default:
+		return "?";
+	}
+}
+
+static void print_reg(unsigned int reg, int offset)
+{
+	if (reg == ORC_REG_BP_INDIRECT)
+		printf("(bp%+d)", offset);
+	else if (reg == ORC_REG_SP_INDIRECT)
+		printf("(sp%+d)", offset);
+	else if (reg == ORC_REG_UNDEFINED)
+		printf("(und)");
+	else
+		printf("%s%+d", reg_name(reg), offset);
+}
+
+int orc_dump(const char *_objname)
+{
+	int fd, nr_entries, i, *orc_ip = NULL, orc_size = 0;
+	struct orc_entry *orc = NULL;
+	char *name;
+	size_t nr_sections;
+	Elf64_Addr orc_ip_addr = 0;
+	size_t shstrtab_idx, strtab_idx = 0;
+	Elf *elf;
+	Elf_Scn *scn;
+	GElf_Shdr sh;
+	GElf_Rela rela;
+	GElf_Sym sym;
+	Elf_Data *data, *symtab = NULL, *rela_orc_ip = NULL;
+
+
+	objname = _objname;
+
+	elf_version(EV_CURRENT);
+
+	fd = open(objname, O_RDONLY);
+	if (fd == -1) {
+		perror("open");
+		return -1;
+	}
+
+	elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
+	if (!elf) {
+		WARN_ELF("elf_begin");
+		return -1;
+	}
+
+	if (elf_getshdrnum(elf, &nr_sections)) {
+		WARN_ELF("elf_getshdrnum");
+		return -1;
+	}
+
+	if (elf_getshdrstrndx(elf, &shstrtab_idx)) {
+		WARN_ELF("elf_getshdrstrndx");
+		return -1;
+	}
+
+	for (i = 0; i < nr_sections; i++) {
+		scn = elf_getscn(elf, i);
+		if (!scn) {
+			WARN_ELF("elf_getscn");
+			return -1;
+		}
+
+		if (!gelf_getshdr(scn, &sh)) {
+			WARN_ELF("gelf_getshdr");
+			return -1;
+		}
+
+		name = elf_strptr(elf, shstrtab_idx, sh.sh_name);
+		if (!name) {
+			WARN_ELF("elf_strptr");
+			return -1;
+		}
+
+		data = elf_getdata(scn, NULL);
+		if (!data) {
+			WARN_ELF("elf_getdata");
+			return -1;
+		}
+
+		if (!strcmp(name, ".symtab")) {
+			symtab = data;
+		} else if (!strcmp(name, ".strtab")) {
+			strtab_idx = i;
+		} else if (!strcmp(name, ".orc_unwind")) {
+			orc = data->d_buf;
+			orc_size = sh.sh_size;
+		} else if (!strcmp(name, ".orc_unwind_ip")) {
+			orc_ip = data->d_buf;
+			orc_ip_addr = sh.sh_addr;
+		} else if (!strcmp(name, ".rela.orc_unwind_ip")) {
+			rela_orc_ip = data;
+		}
+	}
+
+	if (!symtab || !strtab_idx || !orc || !orc_ip)
+		return 0;
+
+	if (orc_size % sizeof(*orc) != 0) {
+		WARN("bad .orc_unwind section size");
+		return -1;
+	}
+
+	nr_entries = orc_size / sizeof(*orc);
+	for (i = 0; i < nr_entries; i++) {
+		if (rela_orc_ip) {
+			if (!gelf_getrela(rela_orc_ip, i, &rela)) {
+				WARN_ELF("gelf_getrela");
+				return -1;
+			}
+
+			if (!gelf_getsym(symtab, GELF_R_SYM(rela.r_info), &sym)) {
+				WARN_ELF("gelf_getsym");
+				return -1;
+			}
+
+			if (GELF_ST_TYPE(sym.st_info) == STT_SECTION) {
+				scn = elf_getscn(elf, sym.st_shndx);
+				if (!scn) {
+					WARN_ELF("elf_getscn");
+					return -1;
+				}
+
+				if (!gelf_getshdr(scn, &sh)) {
+					WARN_ELF("gelf_getshdr");
+					return -1;
+				}
+
+				name = elf_strptr(elf, shstrtab_idx, sh.sh_name);
+				if (!name) {
+					WARN_ELF("elf_strptr");
+					return -1;
+				}
+			} else {
+				name = elf_strptr(elf, strtab_idx, sym.st_name);
+				if (!name) {
+					WARN_ELF("elf_strptr");
+					return -1;
+				}
+			}
+
+			printf("%s+%llx:", name, (unsigned long long)rela.r_addend);
+
+		} else {
+			printf("%llx:", (unsigned long long)(orc_ip_addr + (i * sizeof(int)) + orc_ip[i]));
+		}
+
+
+		printf(" sp:");
+
+		print_reg(orc[i].sp_reg, orc[i].sp_offset);
+
+		printf(" bp:");
+
+		print_reg(orc[i].bp_reg, orc[i].bp_offset);
+
+		printf(" type:%s end:%d\n",
+		       orc_type_name(orc[i].type), orc[i].end);
+	}
+
+	elf_end(elf);
+	close(fd);
+
+	return 0;
+}
diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c
new file mode 100644
index 000000000..812b33ed9
--- /dev/null
+++ b/tools/objtool/orc_gen.c
@@ -0,0 +1,242 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <linux/objtool.h>
+#include <asm/orc_types.h>
+
+#include "check.h"
+#include "warn.h"
+
+static int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi,
+			  struct instruction *insn)
+{
+	struct cfi_reg *bp = &cfi->regs[CFI_BP];
+
+	memset(orc, 0, sizeof(*orc));
+
+	if (!cfi) {
+		orc->end = 0;
+		orc->sp_reg = ORC_REG_UNDEFINED;
+		return 0;
+	}
+
+	orc->end = cfi->end;
+
+	if (cfi->cfa.base == CFI_UNDEFINED) {
+		orc->sp_reg = ORC_REG_UNDEFINED;
+		return 0;
+	}
+
+	switch (cfi->cfa.base) {
+	case CFI_SP:
+		orc->sp_reg = ORC_REG_SP;
+		break;
+	case CFI_SP_INDIRECT:
+		orc->sp_reg = ORC_REG_SP_INDIRECT;
+		break;
+	case CFI_BP:
+		orc->sp_reg = ORC_REG_BP;
+		break;
+	case CFI_BP_INDIRECT:
+		orc->sp_reg = ORC_REG_BP_INDIRECT;
+		break;
+	case CFI_R10:
+		orc->sp_reg = ORC_REG_R10;
+		break;
+	case CFI_R13:
+		orc->sp_reg = ORC_REG_R13;
+		break;
+	case CFI_DI:
+		orc->sp_reg = ORC_REG_DI;
+		break;
+	case CFI_DX:
+		orc->sp_reg = ORC_REG_DX;
+		break;
+	default:
+		WARN_FUNC("unknown CFA base reg %d",
+			  insn->sec, insn->offset, cfi->cfa.base);
+		return -1;
+	}
+
+	switch (bp->base) {
+	case CFI_UNDEFINED:
+		orc->bp_reg = ORC_REG_UNDEFINED;
+		break;
+	case CFI_CFA:
+		orc->bp_reg = ORC_REG_PREV_SP;
+		break;
+	case CFI_BP:
+		orc->bp_reg = ORC_REG_BP;
+		break;
+	default:
+		WARN_FUNC("unknown BP base reg %d",
+			  insn->sec, insn->offset, bp->base);
+		return -1;
+	}
+
+	orc->sp_offset = cfi->cfa.offset;
+	orc->bp_offset = bp->offset;
+	orc->type = cfi->type;
+
+	return 0;
+}
+
+static int write_orc_entry(struct elf *elf, struct section *orc_sec,
+			   struct section *ip_sec, unsigned int idx,
+			   struct section *insn_sec, unsigned long insn_off,
+			   struct orc_entry *o)
+{
+	struct orc_entry *orc;
+
+	/* populate ORC data */
+	orc = (struct orc_entry *)orc_sec->data->d_buf + idx;
+	memcpy(orc, o, sizeof(*orc));
+
+	/* populate reloc for ip */
+	if (elf_add_reloc_to_insn(elf, ip_sec, idx * sizeof(int), R_X86_64_PC32,
+				  insn_sec, insn_off))
+		return -1;
+
+	return 0;
+}
+
+struct orc_list_entry {
+	struct list_head list;
+	struct orc_entry orc;
+	struct section *insn_sec;
+	unsigned long insn_off;
+};
+
+static int orc_list_add(struct list_head *orc_list, struct orc_entry *orc,
+			struct section *sec, unsigned long offset)
+{
+	struct orc_list_entry *entry = malloc(sizeof(*entry));
+
+	if (!entry) {
+		WARN("malloc failed");
+		return -1;
+	}
+
+	entry->orc	= *orc;
+	entry->insn_sec = sec;
+	entry->insn_off = offset;
+
+	list_add_tail(&entry->list, orc_list);
+	return 0;
+}
+
+static unsigned long alt_group_len(struct alt_group *alt_group)
+{
+	return alt_group->last_insn->offset +
+	       alt_group->last_insn->len -
+	       alt_group->first_insn->offset;
+}
+
+int orc_create(struct objtool_file *file)
+{
+	struct section *sec, *orc_sec;
+	unsigned int nr = 0, idx = 0;
+	struct orc_list_entry *entry;
+	struct list_head orc_list;
+
+	struct orc_entry null = {
+		.sp_reg  = ORC_REG_UNDEFINED,
+		.bp_reg  = ORC_REG_UNDEFINED,
+		.type    = UNWIND_HINT_TYPE_CALL,
+	};
+
+	/* Build a deduplicated list of ORC entries: */
+	INIT_LIST_HEAD(&orc_list);
+	for_each_sec(file, sec) {
+		struct orc_entry orc, prev_orc = {0};
+		struct instruction *insn;
+		bool empty = true;
+
+		if (!sec->text)
+			continue;
+
+		sec_for_each_insn(file, sec, insn) {
+			struct alt_group *alt_group = insn->alt_group;
+			int i;
+
+			if (!alt_group) {
+				if (init_orc_entry(&orc, insn->cfi, insn))
+					return -1;
+				if (!memcmp(&prev_orc, &orc, sizeof(orc)))
+					continue;
+				if (orc_list_add(&orc_list, &orc, sec,
+						 insn->offset))
+					return -1;
+				nr++;
+				prev_orc = orc;
+				empty = false;
+				continue;
+			}
+
+			/*
+			 * Alternatives can have different stack layout
+			 * possibilities (but they shouldn't conflict).
+			 * Instead of traversing the instructions, use the
+			 * alt_group's flattened byte-offset-addressed CFI
+			 * array.
+			 */
+			for (i = 0; i < alt_group_len(alt_group); i++) {
+				struct cfi_state *cfi = alt_group->cfi[i];
+				if (!cfi)
+					continue;
+				/* errors are reported on the original insn */
+				if (init_orc_entry(&orc, cfi, insn))
+					return -1;
+				if (!memcmp(&prev_orc, &orc, sizeof(orc)))
+					continue;
+				if (orc_list_add(&orc_list, &orc, insn->sec,
+						 insn->offset + i))
+					return -1;
+				nr++;
+				prev_orc = orc;
+				empty = false;
+			}
+
+			/* Skip to the end of the alt_group */
+			insn = alt_group->last_insn;
+		}
+
+		/* Add a section terminator */
+		if (!empty) {
+			orc_list_add(&orc_list, &null, sec, sec->len);
+			nr++;
+		}
+	}
+	if (!nr)
+		return 0;
+
+	/* Create .orc_unwind, .orc_unwind_ip and .rela.orc_unwind_ip sections: */
+	sec = find_section_by_name(file->elf, ".orc_unwind");
+	if (sec) {
+		WARN("file already has .orc_unwind section, skipping");
+		return -1;
+	}
+	orc_sec = elf_create_section(file->elf, ".orc_unwind", 0,
+				     sizeof(struct orc_entry), nr);
+	if (!orc_sec)
+		return -1;
+
+	sec = elf_create_section(file->elf, ".orc_unwind_ip", 0, sizeof(int), nr);
+	if (!sec)
+		return -1;
+
+	/* Write ORC entries to sections: */
+	list_for_each_entry(entry, &orc_list, list) {
+		if (write_orc_entry(file->elf, orc_sec, sec, idx++,
+				    entry->insn_sec, entry->insn_off,
+				    &entry->orc))
+			return -1;
+	}
+
+	return 0;
+}
diff --git a/tools/objtool/special.c b/tools/objtool/special.c
new file mode 100644
index 000000000..aff0cee7b
--- /dev/null
+++ b/tools/objtool/special.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+/*
+ * This file reads all the special sections which have alternate instructions
+ * which can be patched in or redirected to at runtime.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "builtin.h"
+#include "special.h"
+#include "warn.h"
+#include "arch_special.h"
+
+struct special_entry {
+	const char *sec;
+	bool group, jump_or_nop;
+	unsigned char size, orig, new;
+	unsigned char orig_len, new_len; /* group only */
+	unsigned char feature; /* ALTERNATIVE macro CPU feature */
+};
+
+struct special_entry entries[] = {
+	{
+		.sec = ".altinstructions",
+		.group = true,
+		.size = ALT_ENTRY_SIZE,
+		.orig = ALT_ORIG_OFFSET,
+		.orig_len = ALT_ORIG_LEN_OFFSET,
+		.new = ALT_NEW_OFFSET,
+		.new_len = ALT_NEW_LEN_OFFSET,
+		.feature = ALT_FEATURE_OFFSET,
+	},
+	{
+		.sec = "__jump_table",
+		.jump_or_nop = true,
+		.size = JUMP_ENTRY_SIZE,
+		.orig = JUMP_ORIG_OFFSET,
+		.new = JUMP_NEW_OFFSET,
+	},
+	{
+		.sec = "__ex_table",
+		.size = EX_ENTRY_SIZE,
+		.orig = EX_ORIG_OFFSET,
+		.new = EX_NEW_OFFSET,
+	},
+	{},
+};
+
+void __weak arch_handle_alternative(unsigned short feature, struct special_alt *alt)
+{
+}
+
+static void reloc_to_sec_off(struct reloc *reloc, struct section **sec,
+			     unsigned long *off)
+{
+	*sec = reloc->sym->sec;
+	*off = reloc->sym->offset + reloc->addend;
+}
+
+static int get_alt_entry(struct elf *elf, struct special_entry *entry,
+			 struct section *sec, int idx,
+			 struct special_alt *alt)
+{
+	struct reloc *orig_reloc, *new_reloc;
+	unsigned long offset;
+
+	offset = idx * entry->size;
+
+	alt->group = entry->group;
+	alt->jump_or_nop = entry->jump_or_nop;
+
+	if (alt->group) {
+		alt->orig_len = *(unsigned char *)(sec->data->d_buf + offset +
+						   entry->orig_len);
+		alt->new_len = *(unsigned char *)(sec->data->d_buf + offset +
+						  entry->new_len);
+	}
+
+	if (entry->feature) {
+		unsigned short feature;
+
+		feature = *(unsigned short *)(sec->data->d_buf + offset +
+					      entry->feature);
+		arch_handle_alternative(feature, alt);
+	}
+
+	orig_reloc = find_reloc_by_dest(elf, sec, offset + entry->orig);
+	if (!orig_reloc) {
+		WARN_FUNC("can't find orig reloc", sec, offset + entry->orig);
+		return -1;
+	}
+
+	reloc_to_sec_off(orig_reloc, &alt->orig_sec, &alt->orig_off);
+
+	if (!entry->group || alt->new_len) {
+		new_reloc = find_reloc_by_dest(elf, sec, offset + entry->new);
+		if (!new_reloc) {
+			WARN_FUNC("can't find new reloc",
+				  sec, offset + entry->new);
+			return -1;
+		}
+
+		reloc_to_sec_off(new_reloc, &alt->new_sec, &alt->new_off);
+
+		/* _ASM_EXTABLE_EX hack */
+		if (alt->new_off >= 0x7ffffff0)
+			alt->new_off -= 0x7ffffff0;
+	}
+
+	return 0;
+}
+
+/*
+ * Read all the special sections and create a list of special_alt structs which
+ * describe all the alternate instructions which can be patched in or
+ * redirected to at runtime.
+ */
+int special_get_alts(struct elf *elf, struct list_head *alts)
+{
+	struct special_entry *entry;
+	struct section *sec;
+	unsigned int nr_entries;
+	struct special_alt *alt;
+	int idx, ret;
+
+	INIT_LIST_HEAD(alts);
+
+	for (entry = entries; entry->sec; entry++) {
+		sec = find_section_by_name(elf, entry->sec);
+		if (!sec)
+			continue;
+
+		if (sec->len % entry->size != 0) {
+			WARN("%s size not a multiple of %d",
+			     sec->name, entry->size);
+			return -1;
+		}
+
+		nr_entries = sec->len / entry->size;
+
+		for (idx = 0; idx < nr_entries; idx++) {
+			alt = malloc(sizeof(*alt));
+			if (!alt) {
+				WARN("malloc failed");
+				return -1;
+			}
+			memset(alt, 0, sizeof(*alt));
+
+			ret = get_alt_entry(elf, entry, sec, idx, alt);
+			if (ret > 0)
+				continue;
+			if (ret < 0)
+				return ret;
+
+			list_add_tail(&alt->list, alts);
+		}
+	}
+
+	return 0;
+}
diff --git a/tools/objtool/special.h b/tools/objtool/special.h
new file mode 100644
index 000000000..abddf38ef
--- /dev/null
+++ b/tools/objtool/special.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#ifndef _SPECIAL_H
+#define _SPECIAL_H
+
+#include <stdbool.h>
+#include "check.h"
+#include "elf.h"
+
+#define C_JUMP_TABLE_SECTION ".rodata..c_jump_table"
+
+struct special_alt {
+	struct list_head list;
+
+	bool group;
+	bool skip_orig;
+	bool skip_alt;
+	bool jump_or_nop;
+
+	struct section *orig_sec;
+	unsigned long orig_off;
+
+	struct section *new_sec;
+	unsigned long new_off;
+
+	unsigned int orig_len, new_len; /* group only */
+};
+
+int special_get_alts(struct elf *elf, struct list_head *alts);
+
+void arch_handle_alternative(unsigned short feature, struct special_alt *alt);
+
+bool arch_support_alt_relocation(struct special_alt *special_alt,
+				 struct instruction *insn,
+				 struct reloc *reloc);
+struct reloc *arch_find_switch_table(struct objtool_file *file,
+				    struct instruction *insn);
+#endif /* _SPECIAL_H */
diff --git a/tools/objtool/sync-check.sh b/tools/objtool/sync-check.sh
new file mode 100755
index 000000000..4bbabaeca
--- /dev/null
+++ b/tools/objtool/sync-check.sh
@@ -0,0 +1,74 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+if [ -z "$SRCARCH" ]; then
+	echo 'sync-check.sh: error: missing $SRCARCH environment variable' >&2
+	exit 1
+fi
+
+FILES="include/linux/objtool.h"
+
+if [ "$SRCARCH" = "x86" ]; then
+FILES="$FILES
+arch/x86/include/asm/inat_types.h
+arch/x86/include/asm/orc_types.h
+arch/x86/include/asm/emulate_prefix.h
+arch/x86/lib/x86-opcode-map.txt
+arch/x86/tools/gen-insn-attr-x86.awk
+include/linux/static_call_types.h
+"
+
+SYNC_CHECK_FILES='
+arch/x86/include/asm/inat.h
+arch/x86/include/asm/insn.h
+arch/x86/lib/inat.c
+arch/x86/lib/insn.c
+'
+fi
+
+check_2 () {
+  file1=$1
+  file2=$2
+
+  shift
+  shift
+
+  cmd="diff $* $file1 $file2 > /dev/null"
+
+  test -f $file2 && {
+    eval $cmd || {
+      echo "Warning: Kernel ABI header at '$file1' differs from latest version at '$file2'" >&2
+      echo diff -u $file1 $file2
+    }
+  }
+}
+
+check () {
+  file=$1
+
+  shift
+
+  check_2 tools/$file $file $*
+}
+
+if [ ! -d ../../kernel ] || [ ! -d ../../tools ] || [ ! -d ../objtool ]; then
+	exit 0
+fi
+
+cd ../..
+
+while read -r file_entry; do
+    if [ -z "$file_entry" ]; then
+	continue
+    fi
+
+    check $file_entry
+done <<EOF
+$FILES
+EOF
+
+if [ "$SRCARCH" = "x86" ]; then
+	for i in $SYNC_CHECK_FILES; do
+		check $i '-I "^.*\/\*.*__ignore_sync_check__.*\*\/.*$"'
+	done
+fi
diff --git a/tools/objtool/warn.h b/tools/objtool/warn.h
new file mode 100644
index 000000000..7799f60de
--- /dev/null
+++ b/tools/objtool/warn.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#ifndef _WARN_H
+#define _WARN_H
+
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include "elf.h"
+
+extern const char *objname;
+
+static inline char *offstr(struct section *sec, unsigned long offset)
+{
+	struct symbol *func;
+	char *name, *str;
+	unsigned long name_off;
+
+	func = find_func_containing(sec, offset);
+	if (func) {
+		name = func->name;
+		name_off = offset - func->offset;
+	} else {
+		name = sec->name;
+		name_off = offset;
+	}
+
+	str = malloc(strlen(name) + 20);
+
+	if (func)
+		sprintf(str, "%s()+0x%lx", name, name_off);
+	else
+		sprintf(str, "%s+0x%lx", name, name_off);
+
+	return str;
+}
+
+#define WARN(format, ...)				\
+	fprintf(stderr,					\
+		"%s: warning: objtool: " format "\n",	\
+		objname, ##__VA_ARGS__)
+
+#define WARN_FUNC(format, sec, offset, ...)		\
+({							\
+	char *_str = offstr(sec, offset);		\
+	WARN("%s: " format, _str, ##__VA_ARGS__);	\
+	free(_str);					\
+})
+
+#define BT_FUNC(format, insn, ...)			\
+({							\
+	struct instruction *_insn = (insn);		\
+	char *_str = offstr(_insn->sec, _insn->offset); \
+	WARN("  %s: " format, _str, ##__VA_ARGS__);	\
+	free(_str);					\
+})
+
+#define WARN_ELF(format, ...)				\
+	WARN(format ": %s", ##__VA_ARGS__, elf_errmsg(-1))
+
+#endif /* _WARN_H */
diff --git a/tools/objtool/weak.c b/tools/objtool/weak.c
new file mode 100644
index 000000000..553ec9ce5
--- /dev/null
+++ b/tools/objtool/weak.c
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2020 Matt Helsley <mhelsley@vmware.com>
+ * Weak definitions necessary to compile objtool without
+ * some subcommands (e.g. check, orc).
+ */
+
+#include <stdbool.h>
+#include <errno.h>
+#include "objtool.h"
+
+#define UNSUPPORTED(name)						\
+({									\
+	fprintf(stderr, "error: objtool: " name " not implemented\n");	\
+	return ENOSYS;							\
+})
+
+int __weak check(struct objtool_file *file)
+{
+	UNSUPPORTED("check subcommand");
+}
+
+int __weak orc_dump(const char *_objname)
+{
+	UNSUPPORTED("orc");
+}
+
+int __weak orc_create(struct objtool_file *file)
+{
+	UNSUPPORTED("orc");
+}