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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /arch/x86/kernel/ftrace_64.S
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/x86/kernel/ftrace_64.S')
-rw-r--r--arch/x86/kernel/ftrace_64.S380
1 files changed, 380 insertions, 0 deletions
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
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+++ b/arch/x86/kernel/ftrace_64.S
@@ -0,0 +1,380 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2014 Steven Rostedt, Red Hat Inc
+ */
+
+#include <linux/cfi_types.h>
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+#include <asm/ptrace.h>
+#include <asm/ftrace.h>
+#include <asm/export.h>
+#include <asm/nospec-branch.h>
+#include <asm/unwind_hints.h>
+#include <asm/frame.h>
+
+ .code64
+ .section .text, "ax"
+
+#ifdef CONFIG_FRAME_POINTER
+/* Save parent and function stack frames (rip and rbp) */
+# define MCOUNT_FRAME_SIZE (8+16*2)
+#else
+/* No need to save a stack frame */
+# define MCOUNT_FRAME_SIZE 0
+#endif /* CONFIG_FRAME_POINTER */
+
+/* Size of stack used to save mcount regs in save_mcount_regs */
+#define MCOUNT_REG_SIZE (FRAME_SIZE + MCOUNT_FRAME_SIZE)
+
+/*
+ * gcc -pg option adds a call to 'mcount' in most functions.
+ * When -mfentry is used, the call is to 'fentry' and not 'mcount'
+ * and is done before the function's stack frame is set up.
+ * They both require a set of regs to be saved before calling
+ * any C code and restored before returning back to the function.
+ *
+ * On boot up, all these calls are converted into nops. When tracing
+ * is enabled, the call can jump to either ftrace_caller or
+ * ftrace_regs_caller. Callbacks (tracing functions) that require
+ * ftrace_regs_caller (like kprobes) need to have pt_regs passed to
+ * it. For this reason, the size of the pt_regs structure will be
+ * allocated on the stack and the required mcount registers will
+ * be saved in the locations that pt_regs has them in.
+ */
+
+/*
+ * @added: the amount of stack added before calling this
+ *
+ * After this is called, the following registers contain:
+ *
+ * %rdi - holds the address that called the trampoline
+ * %rsi - holds the parent function (traced function's return address)
+ * %rdx - holds the original %rbp
+ */
+.macro save_mcount_regs added=0
+
+#ifdef CONFIG_FRAME_POINTER
+ /* Save the original rbp */
+ pushq %rbp
+
+ /*
+ * Stack traces will stop at the ftrace trampoline if the frame pointer
+ * is not set up properly. If fentry is used, we need to save a frame
+ * pointer for the parent as well as the function traced, because the
+ * fentry is called before the stack frame is set up, where as mcount
+ * is called afterward.
+ */
+
+ /* Save the parent pointer (skip orig rbp and our return address) */
+ pushq \added+8*2(%rsp)
+ pushq %rbp
+ movq %rsp, %rbp
+ /* Save the return address (now skip orig rbp, rbp and parent) */
+ pushq \added+8*3(%rsp)
+ pushq %rbp
+ movq %rsp, %rbp
+#endif /* CONFIG_FRAME_POINTER */
+
+ /*
+ * We add enough stack to save all regs.
+ */
+ subq $(FRAME_SIZE), %rsp
+ movq %rax, RAX(%rsp)
+ movq %rcx, RCX(%rsp)
+ movq %rdx, RDX(%rsp)
+ movq %rsi, RSI(%rsp)
+ movq %rdi, RDI(%rsp)
+ movq %r8, R8(%rsp)
+ movq %r9, R9(%rsp)
+ movq $0, ORIG_RAX(%rsp)
+ /*
+ * Save the original RBP. Even though the mcount ABI does not
+ * require this, it helps out callers.
+ */
+#ifdef CONFIG_FRAME_POINTER
+ movq MCOUNT_REG_SIZE-8(%rsp), %rdx
+#else
+ movq %rbp, %rdx
+#endif
+ movq %rdx, RBP(%rsp)
+
+ /* Copy the parent address into %rsi (second parameter) */
+ movq MCOUNT_REG_SIZE+8+\added(%rsp), %rsi
+
+ /* Move RIP to its proper location */
+ movq MCOUNT_REG_SIZE+\added(%rsp), %rdi
+ movq %rdi, RIP(%rsp)
+
+ /*
+ * Now %rdi (the first parameter) has the return address of
+ * where ftrace_call returns. But the callbacks expect the
+ * address of the call itself.
+ */
+ subq $MCOUNT_INSN_SIZE, %rdi
+ .endm
+
+.macro restore_mcount_regs save=0
+
+ /* ftrace_regs_caller or frame pointers require this */
+ movq RBP(%rsp), %rbp
+
+ movq R9(%rsp), %r9
+ movq R8(%rsp), %r8
+ movq RDI(%rsp), %rdi
+ movq RSI(%rsp), %rsi
+ movq RDX(%rsp), %rdx
+ movq RCX(%rsp), %rcx
+ movq RAX(%rsp), %rax
+
+ addq $MCOUNT_REG_SIZE-\save, %rsp
+
+ .endm
+
+SYM_TYPED_FUNC_START(ftrace_stub)
+ CALL_DEPTH_ACCOUNT
+ RET
+SYM_FUNC_END(ftrace_stub)
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+SYM_TYPED_FUNC_START(ftrace_stub_graph)
+ CALL_DEPTH_ACCOUNT
+ RET
+SYM_FUNC_END(ftrace_stub_graph)
+#endif
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+SYM_FUNC_START(__fentry__)
+ CALL_DEPTH_ACCOUNT
+ RET
+SYM_FUNC_END(__fentry__)
+EXPORT_SYMBOL(__fentry__)
+
+SYM_FUNC_START(ftrace_caller)
+ /* save_mcount_regs fills in first two parameters */
+ save_mcount_regs
+
+ CALL_DEPTH_ACCOUNT
+
+ /* Stack - skipping return address of ftrace_caller */
+ leaq MCOUNT_REG_SIZE+8(%rsp), %rcx
+ movq %rcx, RSP(%rsp)
+
+SYM_INNER_LABEL(ftrace_caller_op_ptr, SYM_L_GLOBAL)
+ ANNOTATE_NOENDBR
+ /* Load the ftrace_ops into the 3rd parameter */
+ movq function_trace_op(%rip), %rdx
+
+ /* regs go into 4th parameter */
+ leaq (%rsp), %rcx
+
+ /* Only ops with REGS flag set should have CS register set */
+ movq $0, CS(%rsp)
+
+ /* Account for the function call below */
+ CALL_DEPTH_ACCOUNT
+
+SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL)
+ ANNOTATE_NOENDBR
+ call ftrace_stub
+
+ /* Handlers can change the RIP */
+ movq RIP(%rsp), %rax
+ movq %rax, MCOUNT_REG_SIZE(%rsp)
+
+ restore_mcount_regs
+
+ /*
+ * The code up to this label is copied into trampolines so
+ * think twice before adding any new code or changing the
+ * layout here.
+ */
+SYM_INNER_LABEL(ftrace_caller_end, SYM_L_GLOBAL)
+ ANNOTATE_NOENDBR
+ RET
+SYM_FUNC_END(ftrace_caller);
+STACK_FRAME_NON_STANDARD_FP(ftrace_caller)
+
+SYM_FUNC_START(ftrace_regs_caller)
+ /* Save the current flags before any operations that can change them */
+ pushfq
+
+ /* added 8 bytes to save flags */
+ save_mcount_regs 8
+ /* save_mcount_regs fills in first two parameters */
+
+ CALL_DEPTH_ACCOUNT
+
+SYM_INNER_LABEL(ftrace_regs_caller_op_ptr, SYM_L_GLOBAL)
+ ANNOTATE_NOENDBR
+ /* Load the ftrace_ops into the 3rd parameter */
+ movq function_trace_op(%rip), %rdx
+
+ /* Save the rest of pt_regs */
+ movq %r15, R15(%rsp)
+ movq %r14, R14(%rsp)
+ movq %r13, R13(%rsp)
+ movq %r12, R12(%rsp)
+ movq %r11, R11(%rsp)
+ movq %r10, R10(%rsp)
+ movq %rbx, RBX(%rsp)
+ /* Copy saved flags */
+ movq MCOUNT_REG_SIZE(%rsp), %rcx
+ movq %rcx, EFLAGS(%rsp)
+ /* Kernel segments */
+ movq $__KERNEL_DS, %rcx
+ movq %rcx, SS(%rsp)
+ movq $__KERNEL_CS, %rcx
+ movq %rcx, CS(%rsp)
+ /* Stack - skipping return address and flags */
+ leaq MCOUNT_REG_SIZE+8*2(%rsp), %rcx
+ movq %rcx, RSP(%rsp)
+
+ ENCODE_FRAME_POINTER
+
+ /* regs go into 4th parameter */
+ leaq (%rsp), %rcx
+
+ /* Account for the function call below */
+ CALL_DEPTH_ACCOUNT
+
+SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL)
+ ANNOTATE_NOENDBR
+ call ftrace_stub
+
+ /* Copy flags back to SS, to restore them */
+ movq EFLAGS(%rsp), %rax
+ movq %rax, MCOUNT_REG_SIZE(%rsp)
+
+ /* Handlers can change the RIP */
+ movq RIP(%rsp), %rax
+ movq %rax, MCOUNT_REG_SIZE+8(%rsp)
+
+ /* restore the rest of pt_regs */
+ movq R15(%rsp), %r15
+ movq R14(%rsp), %r14
+ movq R13(%rsp), %r13
+ movq R12(%rsp), %r12
+ movq R10(%rsp), %r10
+ movq RBX(%rsp), %rbx
+
+ movq ORIG_RAX(%rsp), %rax
+ movq %rax, MCOUNT_REG_SIZE-8(%rsp)
+
+ /*
+ * If ORIG_RAX is anything but zero, make this a call to that.
+ * See arch_ftrace_set_direct_caller().
+ */
+ testq %rax, %rax
+SYM_INNER_LABEL(ftrace_regs_caller_jmp, SYM_L_GLOBAL)
+ ANNOTATE_NOENDBR
+ jnz 1f
+
+ restore_mcount_regs
+ /* Restore flags */
+ popfq
+
+ /*
+ * The trampoline will add the return.
+ */
+SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL)
+ ANNOTATE_NOENDBR
+ RET
+
+ /* Swap the flags with orig_rax */
+1: movq MCOUNT_REG_SIZE(%rsp), %rdi
+ movq %rdi, MCOUNT_REG_SIZE-8(%rsp)
+ movq %rax, MCOUNT_REG_SIZE(%rsp)
+
+ restore_mcount_regs 8
+ /* Restore flags */
+ popfq
+ UNWIND_HINT_FUNC
+
+ /*
+ * The above left an extra return value on the stack; effectively
+ * doing a tail-call without using a register. This PUSH;RET
+ * pattern unbalances the RSB, inject a pointless CALL to rebalance.
+ */
+ ANNOTATE_INTRA_FUNCTION_CALL
+ CALL .Ldo_rebalance
+ int3
+.Ldo_rebalance:
+ add $8, %rsp
+ ALTERNATIVE __stringify(RET), \
+ __stringify(ANNOTATE_UNRET_SAFE; ret; int3), \
+ X86_FEATURE_CALL_DEPTH
+
+SYM_FUNC_END(ftrace_regs_caller)
+STACK_FRAME_NON_STANDARD_FP(ftrace_regs_caller)
+
+SYM_FUNC_START(ftrace_stub_direct_tramp)
+ CALL_DEPTH_ACCOUNT
+ RET
+SYM_FUNC_END(ftrace_stub_direct_tramp)
+
+#else /* ! CONFIG_DYNAMIC_FTRACE */
+
+SYM_FUNC_START(__fentry__)
+ CALL_DEPTH_ACCOUNT
+
+ cmpq $ftrace_stub, ftrace_trace_function
+ jnz trace
+ RET
+
+trace:
+ /* save_mcount_regs fills in first two parameters */
+ save_mcount_regs
+
+ /*
+ * When DYNAMIC_FTRACE is not defined, ARCH_SUPPORTS_FTRACE_OPS is not
+ * set (see include/asm/ftrace.h and include/linux/ftrace.h). Only the
+ * ip and parent ip are used and the list function is called when
+ * function tracing is enabled.
+ */
+ movq ftrace_trace_function, %r8
+ CALL_NOSPEC r8
+ restore_mcount_regs
+
+ jmp ftrace_stub
+SYM_FUNC_END(__fentry__)
+EXPORT_SYMBOL(__fentry__)
+STACK_FRAME_NON_STANDARD_FP(__fentry__)
+
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+SYM_CODE_START(return_to_handler)
+ UNWIND_HINT_UNDEFINED
+ ANNOTATE_NOENDBR
+ subq $24, %rsp
+
+ /* Save the return values */
+ movq %rax, (%rsp)
+ movq %rdx, 8(%rsp)
+ movq %rbp, 16(%rsp)
+ movq %rsp, %rdi
+
+ call ftrace_return_to_handler
+
+ movq %rax, %rdi
+ movq 8(%rsp), %rdx
+ movq (%rsp), %rax
+
+ addq $24, %rsp
+ /*
+ * Jump back to the old return address. This cannot be JMP_NOSPEC rdi
+ * since IBT would demand that contain ENDBR, which simply isn't so for
+ * return addresses. Use a retpoline here to keep the RSB balanced.
+ */
+ ANNOTATE_INTRA_FUNCTION_CALL
+ call .Ldo_rop
+ int3
+.Ldo_rop:
+ mov %rdi, (%rsp)
+ ALTERNATIVE __stringify(RET), \
+ __stringify(ANNOTATE_UNRET_SAFE; ret; int3), \
+ X86_FEATURE_CALL_DEPTH
+SYM_CODE_END(return_to_handler)
+#endif