6.12-stable review patch. If anyone has any objections, please let me know.
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From: Peter Zijlstra peterz@infradead.org
[ Upstream commit 06e24745985c8dd0da18337503afcf2f2fdbdff1 ]
There are no users of annotate_reachable() left.
And the annotate_unreachable() usage in unreachable() is plain wrong; it will hide dangerous fall-through code-gen.
Remove both.
Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Acked-by: Josh Poimboeuf jpoimboe@kernel.org Link: https://lore.kernel.org/r/20241128094312.235637588@infradead.org Stable-dep-of: 73cfc53cc3b6 ("objtool: Fix C jump table annotations for Clang") Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/compiler.h | 27 ------------------------- tools/objtool/check.c | 43 ++-------------------------------------- 2 files changed, 2 insertions(+), 68 deletions(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 0d10d75218f51..75a83394824c4 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -109,35 +109,9 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
/* Unreachable code */ #ifdef CONFIG_OBJTOOL -/* - * These macros help objtool understand GCC code flow for unreachable code. - * The __COUNTER__ based labels are a hack to make each instance of the macros - * unique, to convince GCC not to merge duplicate inline asm statements. - */ -#define __stringify_label(n) #n - -#define __annotate_reachable(c) ({ \ - asm volatile(__stringify_label(c) ":\n\t" \ - ".pushsection .discard.reachable\n\t" \ - ".long " __stringify_label(c) "b - .\n\t" \ - ".popsection\n\t"); \ -}) -#define annotate_reachable() __annotate_reachable(__COUNTER__) - -#define __annotate_unreachable(c) ({ \ - asm volatile(__stringify_label(c) ":\n\t" \ - ".pushsection .discard.unreachable\n\t" \ - ".long " __stringify_label(c) "b - .\n\t" \ - ".popsection\n\t" : : "i" (c)); \ -}) -#define annotate_unreachable() __annotate_unreachable(__COUNTER__) - /* Annotate a C jump table to allow objtool to follow the code flow */ #define __annotate_jump_table __section(".rodata..c_jump_table,"a",@progbits #") - #else /* !CONFIG_OBJTOOL */ -#define annotate_reachable() -#define annotate_unreachable() #define __annotate_jump_table #endif /* CONFIG_OBJTOOL */
@@ -147,7 +121,6 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, * control elsewhere. */ #define unreachable() do { \ - annotate_unreachable(); \ barrier_before_unreachable(); \ __builtin_unreachable(); \ } while (0) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 8e02db7e83323..3e72c9f9b7f37 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -639,47 +639,8 @@ static int add_dead_ends(struct objtool_file *file) uint64_t offset;
/* - * Check for manually annotated dead ends. - */ - rsec = find_section_by_name(file->elf, ".rela.discard.unreachable"); - if (!rsec) - goto reachable; - - for_each_reloc(rsec, reloc) { - if (reloc->sym->type == STT_SECTION) { - offset = reloc_addend(reloc); - } else if (reloc->sym->local_label) { - offset = reloc->sym->offset; - } else { - WARN("unexpected relocation symbol type in %s", rsec->name); - return -1; - } - - insn = find_insn(file, reloc->sym->sec, offset); - if (insn) - insn = prev_insn_same_sec(file, insn); - else if (offset == reloc->sym->sec->sh.sh_size) { - insn = find_last_insn(file, reloc->sym->sec); - if (!insn) { - WARN("can't find unreachable insn at %s+0x%" PRIx64, - reloc->sym->sec->name, offset); - return -1; - } - } else { - WARN("can't find unreachable insn at %s+0x%" PRIx64, - reloc->sym->sec->name, offset); - 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. + * UD2 defaults to being a dead-end, allow them to be annotated for + * non-fatal, eg WARN. */ rsec = find_section_by_name(file->elf, ".rela.discard.reachable"); if (!rsec)