summaryrefslogtreecommitdiffstats
path: root/arch/x86/purgatory
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/purgatory')
-rw-r--r--arch/x86/purgatory/.gitignore1
-rw-r--r--arch/x86/purgatory/Makefile88
-rw-r--r--arch/x86/purgatory/entry64.S103
-rw-r--r--arch/x86/purgatory/purgatory.c57
-rw-r--r--arch/x86/purgatory/setup-x86_64.S59
-rw-r--r--arch/x86/purgatory/stack.S18
6 files changed, 326 insertions, 0 deletions
diff --git a/arch/x86/purgatory/.gitignore b/arch/x86/purgatory/.gitignore
new file mode 100644
index 000000000..d2be15006
--- /dev/null
+++ b/arch/x86/purgatory/.gitignore
@@ -0,0 +1 @@
+purgatory.chk
diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
new file mode 100644
index 000000000..dc0b91c1d
--- /dev/null
+++ b/arch/x86/purgatory/Makefile
@@ -0,0 +1,88 @@
+# SPDX-License-Identifier: GPL-2.0
+OBJECT_FILES_NON_STANDARD := y
+
+purgatory-y := purgatory.o stack.o setup-x86_$(BITS).o sha256.o entry64.o string.o
+
+targets += $(purgatory-y)
+PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y))
+
+$(obj)/string.o: $(srctree)/arch/x86/boot/compressed/string.c FORCE
+ $(call if_changed_rule,cc_o_c)
+
+$(obj)/sha256.o: $(srctree)/lib/crypto/sha256.c FORCE
+ $(call if_changed_rule,cc_o_c)
+
+CFLAGS_sha256.o := -D__DISABLE_EXPORTS
+
+# When profile-guided optimization is enabled, llvm emits two different
+# overlapping text sections, which is not supported by kexec. Remove profile
+# optimization flags.
+KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS))
+
+# When linking purgatory.ro with -r unresolved symbols are not checked,
+# also link a purgatory.chk binary without -r to check for unresolved symbols.
+PURGATORY_LDFLAGS := -e purgatory_start -nostdlib -z nodefaultlib
+LDFLAGS_purgatory.ro := -r $(PURGATORY_LDFLAGS)
+LDFLAGS_purgatory.chk := $(PURGATORY_LDFLAGS)
+targets += purgatory.ro purgatory.chk
+
+# Sanitizer, etc. runtimes are unavailable and cannot be linked here.
+GCOV_PROFILE := n
+KASAN_SANITIZE := n
+UBSAN_SANITIZE := n
+KCSAN_SANITIZE := n
+KCOV_INSTRUMENT := n
+
+# These are adjustments to the compiler flags used for objects that
+# make up the standalone purgatory.ro
+
+PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel
+PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss -g0
+PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING
+PURGATORY_CFLAGS += -fno-stack-protector
+
+# Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That
+# in turn leaves some undefined symbols like __fentry__ in purgatory and not
+# sure how to relocate those.
+ifdef CONFIG_FUNCTION_TRACER
+PURGATORY_CFLAGS_REMOVE += $(CC_FLAGS_FTRACE)
+endif
+
+ifdef CONFIG_STACKPROTECTOR
+PURGATORY_CFLAGS_REMOVE += -fstack-protector
+endif
+
+ifdef CONFIG_STACKPROTECTOR_STRONG
+PURGATORY_CFLAGS_REMOVE += -fstack-protector-strong
+endif
+
+ifdef CONFIG_RETPOLINE
+PURGATORY_CFLAGS_REMOVE += $(RETPOLINE_CFLAGS)
+endif
+
+CFLAGS_REMOVE_purgatory.o += $(PURGATORY_CFLAGS_REMOVE)
+CFLAGS_purgatory.o += $(PURGATORY_CFLAGS)
+
+CFLAGS_REMOVE_sha256.o += $(PURGATORY_CFLAGS_REMOVE)
+CFLAGS_sha256.o += $(PURGATORY_CFLAGS)
+
+CFLAGS_REMOVE_string.o += $(PURGATORY_CFLAGS_REMOVE)
+CFLAGS_string.o += $(PURGATORY_CFLAGS)
+
+asflags-remove-y += -g -Wa,-gdwarf-2
+
+$(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
+ $(call if_changed,ld)
+
+$(obj)/purgatory.chk: $(obj)/purgatory.ro FORCE
+ $(call if_changed,ld)
+
+targets += kexec-purgatory.c
+
+quiet_cmd_bin2c = BIN2C $@
+ cmd_bin2c = $(objtree)/scripts/bin2c kexec_purgatory < $< > $@
+
+$(obj)/kexec-purgatory.c: $(obj)/purgatory.ro $(obj)/purgatory.chk FORCE
+ $(call if_changed,bin2c)
+
+obj-$(CONFIG_KEXEC_FILE) += kexec-purgatory.o
diff --git a/arch/x86/purgatory/entry64.S b/arch/x86/purgatory/entry64.S
new file mode 100644
index 000000000..0b4390ce5
--- /dev/null
+++ b/arch/x86/purgatory/entry64.S
@@ -0,0 +1,103 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2003,2004 Eric Biederman (ebiederm@xmission.com)
+ * Copyright (C) 2014 Red Hat Inc.
+
+ * Author(s): Vivek Goyal <vgoyal@redhat.com>
+ *
+ * This code has been taken from kexec-tools.
+ */
+
+#include <linux/linkage.h>
+
+ .text
+ .balign 16
+ .code64
+
+SYM_CODE_START(entry64)
+ /* Setup a gdt that should be preserved */
+ lgdt gdt(%rip)
+
+ /* load the data segments */
+ movl $0x18, %eax /* data segment */
+ movl %eax, %ds
+ movl %eax, %es
+ movl %eax, %ss
+ movl %eax, %fs
+ movl %eax, %gs
+
+ /* Setup new stack */
+ leaq stack_init(%rip), %rsp
+ pushq $0x10 /* CS */
+ leaq new_cs_exit(%rip), %rax
+ pushq %rax
+ lretq
+new_cs_exit:
+
+ /* Load the registers */
+ movq rax(%rip), %rax
+ movq rbx(%rip), %rbx
+ movq rcx(%rip), %rcx
+ movq rdx(%rip), %rdx
+ movq rsi(%rip), %rsi
+ movq rdi(%rip), %rdi
+ movq rsp(%rip), %rsp
+ movq rbp(%rip), %rbp
+ movq r8(%rip), %r8
+ movq r9(%rip), %r9
+ movq r10(%rip), %r10
+ movq r11(%rip), %r11
+ movq r12(%rip), %r12
+ movq r13(%rip), %r13
+ movq r14(%rip), %r14
+ movq r15(%rip), %r15
+
+ /* Jump to the new code... */
+ jmpq *rip(%rip)
+SYM_CODE_END(entry64)
+
+ .section ".rodata"
+ .balign 4
+SYM_DATA_START(entry64_regs)
+rax: .quad 0x0
+rcx: .quad 0x0
+rdx: .quad 0x0
+rbx: .quad 0x0
+rsp: .quad 0x0
+rbp: .quad 0x0
+rsi: .quad 0x0
+rdi: .quad 0x0
+r8: .quad 0x0
+r9: .quad 0x0
+r10: .quad 0x0
+r11: .quad 0x0
+r12: .quad 0x0
+r13: .quad 0x0
+r14: .quad 0x0
+r15: .quad 0x0
+rip: .quad 0x0
+SYM_DATA_END(entry64_regs)
+
+ /* GDT */
+ .section ".rodata"
+ .balign 16
+SYM_DATA_START_LOCAL(gdt)
+ /*
+ * 0x00 unusable segment
+ * 0x08 unused
+ * so use them as gdt ptr
+ */
+ .word gdt_end - gdt - 1
+ .quad gdt
+ .word 0, 0, 0
+
+ /* 0x10 4GB flat code segment */
+ .word 0xFFFF, 0x0000, 0x9A00, 0x00AF
+
+ /* 0x18 4GB flat data segment */
+ .word 0xFFFF, 0x0000, 0x9200, 0x00CF
+SYM_DATA_END_LABEL(gdt, SYM_L_LOCAL, gdt_end)
+
+SYM_DATA_START_LOCAL(stack)
+ .quad 0, 0
+SYM_DATA_END_LABEL(stack, SYM_L_LOCAL, stack_init)
diff --git a/arch/x86/purgatory/purgatory.c b/arch/x86/purgatory/purgatory.c
new file mode 100644
index 000000000..7b37a412f
--- /dev/null
+++ b/arch/x86/purgatory/purgatory.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * purgatory: Runs between two kernels
+ *
+ * Copyright (C) 2014 Red Hat Inc.
+ *
+ * Author:
+ * Vivek Goyal <vgoyal@redhat.com>
+ */
+
+#include <linux/bug.h>
+#include <crypto/sha.h>
+#include <asm/purgatory.h>
+
+#include "../boot/string.h"
+
+u8 purgatory_sha256_digest[SHA256_DIGEST_SIZE] __section(".kexec-purgatory");
+
+struct kexec_sha_region purgatory_sha_regions[KEXEC_SEGMENT_MAX] __section(".kexec-purgatory");
+
+static int verify_sha256_digest(void)
+{
+ struct kexec_sha_region *ptr, *end;
+ u8 digest[SHA256_DIGEST_SIZE];
+ struct sha256_state sctx;
+
+ sha256_init(&sctx);
+ end = purgatory_sha_regions + ARRAY_SIZE(purgatory_sha_regions);
+
+ for (ptr = purgatory_sha_regions; ptr < end; ptr++)
+ sha256_update(&sctx, (uint8_t *)(ptr->start), ptr->len);
+
+ sha256_final(&sctx, digest);
+
+ if (memcmp(digest, purgatory_sha256_digest, sizeof(digest)))
+ return 1;
+
+ return 0;
+}
+
+void purgatory(void)
+{
+ int ret;
+
+ ret = verify_sha256_digest();
+ if (ret) {
+ /* loop forever */
+ for (;;)
+ ;
+ }
+}
+
+/*
+ * Defined in order to reuse memcpy() and memset() from
+ * arch/x86/boot/compressed/string.c
+ */
+void warn(const char *msg) {}
diff --git a/arch/x86/purgatory/setup-x86_64.S b/arch/x86/purgatory/setup-x86_64.S
new file mode 100644
index 000000000..89d9e9e53
--- /dev/null
+++ b/arch/x86/purgatory/setup-x86_64.S
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * purgatory: setup code
+ *
+ * Copyright (C) 2003,2004 Eric Biederman (ebiederm@xmission.com)
+ * Copyright (C) 2014 Red Hat Inc.
+ *
+ * This code has been taken from kexec-tools.
+ */
+#include <linux/linkage.h>
+#include <asm/purgatory.h>
+
+ .text
+ .balign 16
+ .code64
+
+SYM_CODE_START(purgatory_start)
+ /* Load a gdt so I know what the segment registers are */
+ lgdt gdt(%rip)
+
+ /* load the data segments */
+ movl $0x18, %eax /* data segment */
+ movl %eax, %ds
+ movl %eax, %es
+ movl %eax, %ss
+ movl %eax, %fs
+ movl %eax, %gs
+
+ /* Setup a stack */
+ leaq lstack_end(%rip), %rsp
+
+ /* Call the C code */
+ call purgatory
+ jmp entry64
+SYM_CODE_END(purgatory_start)
+
+ .section ".rodata"
+ .balign 16
+SYM_DATA_START_LOCAL(gdt)
+ /* 0x00 unusable segment
+ * 0x08 unused
+ * so use them as the gdt ptr
+ */
+ .word gdt_end - gdt - 1
+ .quad gdt
+ .word 0, 0, 0
+
+ /* 0x10 4GB flat code segment */
+ .word 0xFFFF, 0x0000, 0x9A00, 0x00AF
+
+ /* 0x18 4GB flat data segment */
+ .word 0xFFFF, 0x0000, 0x9200, 0x00CF
+SYM_DATA_END_LABEL(gdt, SYM_L_LOCAL, gdt_end)
+
+ .bss
+ .balign 4096
+SYM_DATA_START_LOCAL(lstack)
+ .skip 4096
+SYM_DATA_END_LABEL(lstack, SYM_L_LOCAL, lstack_end)
diff --git a/arch/x86/purgatory/stack.S b/arch/x86/purgatory/stack.S
new file mode 100644
index 000000000..1ef507ca5
--- /dev/null
+++ b/arch/x86/purgatory/stack.S
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * purgatory: stack
+ *
+ * Copyright (C) 2014 Red Hat Inc.
+ */
+
+#include <linux/linkage.h>
+
+ /* A stack for the loaded kernel.
+ * Separate and in the data section so it can be prepopulated.
+ */
+ .data
+ .balign 4096
+
+SYM_DATA_START(stack)
+ .skip 4096
+SYM_DATA_END_LABEL(stack, SYM_L_GLOBAL, stack_end)
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-27 05:50:55 +0000