diff options
| -rw-r--r-- | Makefile | 24 | ||||
| -rw-r--r-- | arch/x86/kernel/vmlinux.lds.S | 1 | ||||
| -rw-r--r-- | include/linux/compiler-gcc.h | 14 | ||||
| -rw-r--r-- | tools/objtool/arch.h | 5 | ||||
| -rw-r--r-- | tools/objtool/arch/x86/decode.c | 3 | ||||
| -rw-r--r-- | tools/objtool/builtin-check.c | 60 |
6 files changed, 84 insertions, 23 deletions
@@ -910,6 +910,18 @@ mod_sign_cmd = true endif export mod_sign_cmd +ifdef CONFIG_STACK_VALIDATION + has_libelf := $(call try-run,\ + echo "int main() {}" | $(HOSTCC) -xc -o /dev/null -lelf -,1,0) + ifeq ($(has_libelf),1) + objtool_target := tools/objtool FORCE + else + $(warning "Cannot use CONFIG_STACK_VALIDATION, please install libelf-dev, libelf-devel or elfutils-libelf-devel") + SKIP_STACK_VALIDATION := 1 + export SKIP_STACK_VALIDATION + endif +endif + ifeq ($(KBUILD_EXTMOD),) core-y += kernel/ certs/ mm/ fs/ ipc/ security/ crypto/ block/ @@ -1037,18 +1049,6 @@ prepare0: archprepare gcc-plugins # All the preparing.. prepare: prepare0 prepare-objtool -ifdef CONFIG_STACK_VALIDATION - has_libelf := $(call try-run,\ - echo "int main() {}" | $(HOSTCC) -xc -o /dev/null -lelf -,1,0) - ifeq ($(has_libelf),1) - objtool_target := tools/objtool FORCE - else - $(warning "Cannot use CONFIG_STACK_VALIDATION, please install libelf-dev, libelf-devel or elfutils-libelf-devel") - SKIP_STACK_VALIDATION := 1 - export SKIP_STACK_VALIDATION - endif -endif - PHONY += prepare-objtool prepare-objtool: $(objtool_target) diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index e79f15f108a8..ad0118fbce90 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -346,6 +346,7 @@ SECTIONS /DISCARD/ : { *(.eh_frame) *(__func_stack_frame_non_standard) + *(__unreachable) } } diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 811f7a915658..76e28c229805 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -197,6 +197,17 @@ #endif #endif +#ifdef CONFIG_STACK_VALIDATION +#define annotate_unreachable() ({ \ + asm("%c0:\t\n" \ + ".pushsection __unreachable, \"a\"\t\n" \ + ".long %c0b\t\n" \ + ".popsection\t\n" : : "i" (__LINE__)); \ +}) +#else +#define annotate_unreachable() +#endif + /* * Mark a position in code as unreachable. This can be used to * suppress control flow warnings after asm blocks that transfer @@ -206,7 +217,8 @@ * this in the preprocessor, but we can live with this because they're * unreleased. Really, we need to have autoconf for the kernel. */ -#define unreachable() __builtin_unreachable() +#define unreachable() \ + do { annotate_unreachable(); __builtin_unreachable(); } while (0) /* Mark a function definition as prohibited from being cloned. */ #define __noclone __attribute__((__noclone__, __optimize__("no-tracer"))) diff --git a/tools/objtool/arch.h b/tools/objtool/arch.h index f7350fcedc70..a59e061c0b4a 100644 --- a/tools/objtool/arch.h +++ b/tools/objtool/arch.h @@ -31,9 +31,8 @@ #define INSN_CALL_DYNAMIC 8 #define INSN_RETURN 9 #define INSN_CONTEXT_SWITCH 10 -#define INSN_BUG 11 -#define INSN_NOP 12 -#define INSN_OTHER 13 +#define INSN_NOP 11 +#define INSN_OTHER 12 #define INSN_LAST INSN_OTHER int arch_decode_instruction(struct elf *elf, struct section *sec, diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index 039636ffb6c8..6ac99e3266eb 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -118,9 +118,6 @@ int arch_decode_instruction(struct elf *elf, struct section *sec, 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; diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c index e8a1f699058a..5fc52ee3264c 100644 --- a/tools/objtool/builtin-check.c +++ b/tools/objtool/builtin-check.c @@ -51,7 +51,7 @@ struct instruction { unsigned int len, state; unsigned char type; unsigned long immediate; - bool alt_group, visited; + bool alt_group, visited, dead_end; struct symbol *call_dest; struct instruction *jump_dest; struct list_head alts; @@ -330,6 +330,54 @@ static int decode_instructions(struct objtool_file *file) } /* + * Find all uses of the unreachable() macro, which are code path dead ends. + */ +static int add_dead_ends(struct objtool_file *file) +{ + struct section *sec; + struct rela *rela; + struct instruction *insn; + bool found; + + sec = find_section_by_name(file->elf, ".rela__unreachable"); + if (!sec) + return 0; + + list_for_each_entry(rela, &sec->rela_list, list) { + if (rela->sym->type != STT_SECTION) { + WARN("unexpected relocation symbol type in .rela__unreachable"); + return -1; + } + insn = find_insn(file, rela->sym->sec, rela->addend); + if (insn) + insn = list_prev_entry(insn, list); + else if (rela->addend == rela->sym->sec->len) { + found = false; + list_for_each_entry_reverse(insn, &file->insn_list, list) { + if (insn->sec == rela->sym->sec) { + found = true; + break; + } + } + + if (!found) { + WARN("can't find unreachable insn at %s+0x%x", + rela->sym->sec->name, rela->addend); + return -1; + } + } else { + WARN("can't find unreachable insn at %s+0x%x", + rela->sym->sec->name, rela->addend); + return -1; + } + + insn->dead_end = true; + } + + return 0; +} + +/* * Warnings shouldn't be reported for ignored functions. */ static void add_ignores(struct objtool_file *file) @@ -843,6 +891,10 @@ static int decode_sections(struct objtool_file *file) if (ret) return ret; + ret = add_dead_ends(file); + if (ret) + return ret; + add_ignores(file); ret = add_jump_destinations(file); @@ -1037,13 +1089,13 @@ static int validate_branch(struct objtool_file *file, return 0; - case INSN_BUG: - return 0; - default: break; } + if (insn->dead_end) + return 0; + insn = next_insn_same_sec(file, insn); if (!insn) { WARN("%s: unexpected end of section", sec->name); |