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Message-ID: <fa33720aa6022c6fab2336e129e08575177a8009.1744098446.git.jpoimboe@kernel.org> Date: Tue, 8 Apr 2025 01:21:18 -0700 From: Josh Poimboeuf <jpoimboe@...nel.org> To: x86@...nel.org Cc: linux-kernel@...r.kernel.org, Linus Torvalds <torvalds@...ux-foundation.org>, Ingo Molnar <mingo@...nel.org>, Peter Zijlstra <peterz@...radead.org> Subject: [PATCH RFC 5/5] objtool: Improve code generation readability Improve the readability and compactness of the objtool annotations. This makes it easier to see them and differentiate from other code. Before: ------- 911: .pushsection .discard.annotate_insn,"M",@progbits,8 .long 911b - . .long 1 .popsection After: ------ # <ANNOTATE_NOENDBR> 911: .pushsection .discard.annotate_insn,"M",@progbits,8; .long 911b - .; .long 1; .popsection # </ANNOTATE_NOENDBR> Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org> --- include/linux/objtool.h | 97 ++++++++++++++++++++--------------------- 1 file changed, 47 insertions(+), 50 deletions(-) diff --git a/include/linux/objtool.h b/include/linux/objtool.h index 366ad004d794..66549603147e 100644 --- a/include/linux/objtool.h +++ b/include/linux/objtool.h @@ -8,19 +8,31 @@ #include <asm/asm.h> +#define __UNWIND_HINT(label, type, sp_reg, sp_offset, signal) \ + .pushsection .discard.unwind_hints; \ + /* struct unwind_hint */ \ + .long label - .; \ + .short sp_offset; \ + .byte sp_reg; \ + .byte type; \ + .byte signal; \ + .balign 4; \ + .popsection + +#define __ASM_ANNOTATE(label, type) \ + .pushsection .discard.annotate_insn,"M",@progbits,8; \ + .long label - .; \ + .long type; \ + .popsection + #ifndef __ASSEMBLY__ -#define UNWIND_HINT(type, sp_reg, sp_offset, signal) \ - "987: \n\t" \ - ".pushsection .discard.unwind_hints\n\t" \ - /* struct unwind_hint */ \ - ".long 987b - .\n\t" \ - ".short " __stringify(sp_offset) "\n\t" \ - ".byte " __stringify(sp_reg) "\n\t" \ - ".byte " __stringify(type) "\n\t" \ - ".byte " __stringify(signal) "\n\t" \ - ".balign 4 \n\t" \ - ".popsection\n\t" +#define UNWIND_HINT(type, sp_reg, sp_offset, signal) \ + "\n# <UNWIND_HINT>\n" \ + "987: " \ + __stringify(__UNWIND_HINT(987b, type, sp_reg, \ + sp_offset, signal)) \ + "\n# </UNWIND_HINT>\n\t" /* * This macro marks the given function's stack frame as "non-standard", which @@ -45,23 +57,18 @@ #define STACK_FRAME_NON_STANDARD_FP(func) #endif -#define ASM_REACHABLE \ - "998:\n\t" \ - ".pushsection .discard.reachable\n\t" \ - ".long 998b\n\t" \ - ".popsection\n\t" - #define __ASM_BREF(label) label ## b -#define __ASM_ANNOTATE(label, type) \ - ".pushsection .discard.annotate_insn,\"M\",@progbits,8\n\t" \ - ".long " __stringify(label) " - .\n\t" \ - ".long " __stringify(type) "\n\t" \ - ".popsection\n\t" - #define ASM_ANNOTATE(type) \ - "911:\n\t" \ - __ASM_ANNOTATE(911b, type) + "\n# <ANNOTATE_" __stringify(type) ">\n" \ + "911:\t" \ + __stringify(__ASM_ANNOTATE(911b, __PASTE(ANNOTYPE_, type))) \ + "\n# </ANNOTATE_" __stringify(type) ">\n\t" + +#define ASM_ANNOTATE_LABEL(label, type) \ + "\n# BEGIN ANNOTATE_" __stringify(type) "\n" \ + __stringify(__ASM_ANNOTATE(label, __PASTE(ANNOTYPE_, type))) \ + "\n# </ANNOTATE_" __stringify(type) "\n\t" #else /* __ASSEMBLY__ */ @@ -88,15 +95,7 @@ */ .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 .Lhere_\@: - .pushsection .discard.unwind_hints - /* struct unwind_hint */ - .long .Lhere_\@ - . - .short \sp_offset - .byte \sp_reg - .byte \type - .byte \signal - .balign 4 - .popsection + __UNWIND_HINT(.Lhere_\@, \type, \sp_reg, \sp_offset, \signal) .endm .macro STACK_FRAME_NON_STANDARD func:req @@ -113,10 +112,7 @@ .macro ANNOTATE type:req .Lhere_\@: - .pushsection .discard.annotate_insn,"M",@progbits,8 - .long .Lhere_\@ - . - .long \type - .popsection + __ASM_ANNOTATE(.Lhere_\@, \type) .endm #endif /* __ASSEMBLY__ */ @@ -125,11 +121,12 @@ #ifndef __ASSEMBLY__ -#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(label, type) "" -#define ASM_ANNOTATE(type) + +#define UNWIND_HINT(type, sp_reg, sp_offset, signal) "" +#define ASM_ANNOTATE(type) "" +#define ASM_ANNOTATE_LABEL(sym, type) "" #else .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 .endm @@ -146,30 +143,30 @@ * Annotate away the various 'relocation to !ENDBR` complaints; knowing that * these relocations will never be used for indirect calls. */ -#define ANNOTATE_NOENDBR ASM_ANNOTATE(ANNOTYPE_NOENDBR) -#define ANNOTATE_NOENDBR_SYM(sym) asm(__ASM_ANNOTATE(sym, ANNOTYPE_NOENDBR)) +#define ANNOTATE_NOENDBR ASM_ANNOTATE(NOENDBR) +#define ANNOTATE_NOENDBR_SYM(sym) asm(ASM_ANNOTATE_LABEL(sym, NOENDBR)) /* * This should be used immediately before an indirect jump/call. It tells * objtool the subsequent indirect jump/call is vouched safe for retpoline * builds. */ -#define ANNOTATE_RETPOLINE_SAFE ASM_ANNOTATE(ANNOTYPE_RETPOLINE_SAFE) +#define ANNOTATE_RETPOLINE_SAFE ASM_ANNOTATE(RETPOLINE_SAFE) /* * See linux/instrumentation.h */ -#define ANNOTATE_INSTR_BEGIN(label) __ASM_ANNOTATE(label, ANNOTYPE_INSTR_BEGIN) -#define ANNOTATE_INSTR_END(label) __ASM_ANNOTATE(label, ANNOTYPE_INSTR_END) +#define ANNOTATE_INSTR_BEGIN(label) ASM_ANNOTATE_LABEL(label, INSTR_BEGIN) +#define ANNOTATE_INSTR_END(label) ASM_ANNOTATE_LABEL(label, INSTR_END) /* * objtool annotation to ignore the alternatives and only consider the original * instruction(s). */ -#define ANNOTATE_IGNORE_ALTERNATIVE ASM_ANNOTATE(ANNOTYPE_IGNORE_ALTS) +#define ANNOTATE_IGNORE_ALTERNATIVE ASM_ANNOTATE(IGNORE_ALTS) /* * This macro indicates that the following intra-function call is valid. * Any non-annotated intra-function call will cause objtool to issue a warning. */ -#define ANNOTATE_INTRA_FUNCTION_CALL ASM_ANNOTATE(ANNOTYPE_INTRA_FUNCTION_CALL) +#define ANNOTATE_INTRA_FUNCTION_CALL ASM_ANNOTATE(INTRA_FUNCTION_CALL) /* * Use objtool to validate the entry requirement that all code paths do * VALIDATE_UNRET_END before RET. @@ -177,13 +174,13 @@ * NOTE: The macro must be used at the beginning of a global symbol, otherwise * it will be ignored. */ -#define ANNOTATE_UNRET_BEGIN ASM_ANNOTATE(ANNOTYPE_UNRET_BEGIN) +#define ANNOTATE_UNRET_BEGIN ASM_ANNOTATE(UNRET_BEGIN) /* * This should be used to refer to an instruction that is considered * terminating, like a noreturn CALL or UD2 when we know they are not -- eg * WARN using UD2. */ -#define ANNOTATE_REACHABLE(label) __ASM_ANNOTATE(label, ANNOTYPE_REACHABLE) +#define ANNOTATE_REACHABLE(label) ASM_ANNOTATE_LABEL(label, REACHABLE) #else #define ANNOTATE_NOENDBR ANNOTATE type=ANNOTYPE_NOENDBR -- 2.49.0
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