The following commit has been merged into the objtool/core branch of tip: Commit-ID: 2116b349e29a2e9ba17ea2e45b31234e4b350793 Gitweb: https://git.kernel.org/tip/2116b349e29a2e9ba17ea2e45b31234e4b350793 Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Thu, 28 Nov 2024 10:38:52 +01:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Mon, 02 Dec 2024 12:01:41 +01:00 objtool: Generic annotation infrastructure Avoid endless .discard.foo sections for each annotation, create a single .discard.annotate_insn section that takes an annotation type along with the instruction. Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Link: https://lore.kernel.org/r/20241128094310.932794537@xxxxxxxxxxxxx --- include/linux/objtool.h | 18 ++++++++++++++++- tools/objtool/check.c | 45 ++++++++++++++++++++++++++++++++++++++++- 2 files changed, 63 insertions(+) diff --git a/include/linux/objtool.h b/include/linux/objtool.h index b3b8d3d..d98531e 100644 --- a/include/linux/objtool.h +++ b/include/linux/objtool.h @@ -57,6 +57,13 @@ ".long 998b\n\t" \ ".popsection\n\t" +#define ASM_ANNOTATE(type) \ + "911:\n\t" \ + ".pushsection .discard.annotate_insn,\"M\",@progbits,8\n\t" \ + ".long 911b - .\n\t" \ + ".long " __stringify(type) "\n\t" \ + ".popsection\n\t" + #else /* __ASSEMBLY__ */ /* @@ -146,6 +153,14 @@ .popsection .endm +.macro ANNOTATE type:req +.Lhere_\@: + .pushsection .discard.annotate_insn,"M",@progbits,8 + .long .Lhere_\@ - . + .long \type + .popsection +.endm + #endif /* __ASSEMBLY__ */ #else /* !CONFIG_OBJTOOL */ @@ -155,6 +170,7 @@ #define UNWIND_HINT(type, sp_reg, sp_offset, signal) "\n\t" #define STACK_FRAME_NON_STANDARD(func) #define STACK_FRAME_NON_STANDARD_FP(func) +#define ASM_ANNOTATE(type) #define ANNOTATE_NOENDBR #define ASM_REACHABLE #else @@ -167,6 +183,8 @@ .endm .macro REACHABLE .endm +.macro ANNOTATE type:req +.endm #endif #endif /* CONFIG_OBJTOOL */ diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 4ce176a..b0efc8e 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -2373,6 +2373,49 @@ static int read_unwind_hints(struct objtool_file *file) return 0; } +static int read_annotate(struct objtool_file *file, void (*func)(int type, struct instruction *insn)) +{ + struct section *sec; + struct instruction *insn; + struct reloc *reloc; + int type; + + sec = find_section_by_name(file->elf, ".discard.annotate_insn"); + if (!sec) + return 0; + + if (!sec->rsec) + return 0; + + if (sec->sh.sh_entsize != 8) { + static bool warned = false; + if (!warned) { + WARN("%s: dodgy linker, sh_entsize != 8", sec->name); + warned = true; + } + sec->sh.sh_entsize = 8; + } + + for_each_reloc(sec->rsec, reloc) { + type = *(u32 *)(sec->data->d_buf + (reloc_idx(reloc) * sec->sh.sh_entsize) + 4); + + insn = find_insn(file, reloc->sym->sec, + reloc->sym->offset + reloc_addend(reloc)); + if (!insn) { + WARN("bad .discard.annotate_insn entry: %d of type %d", reloc_idx(reloc), type); + return -1; + } + + func(type, insn); + } + + return 0; +} + +static void __annotate_nop(int type, struct instruction *insn) +{ +} + static int read_noendbr_hints(struct objtool_file *file) { struct instruction *insn; @@ -2670,6 +2713,8 @@ static int decode_sections(struct objtool_file *file) if (ret) return ret; + read_annotate(file, __annotate_nop); + /* * Must be before read_unwind_hints() since that needs insn->noendbr. */
![]() |