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x86/alternative: Remove ANNOTATE_DATA_SPECIAL usage

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Instead of manually annotating each .altinstructions entry, just make
the section mergeable and store the entry size in the ELF section
header.

Either way works for objtool create_fake_symbols(), this way produces
cleaner code generation.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://patch.msgid.link/5ac04e6db5be6453dce8003a771ebb0c47b4cd7a.1764694625.git.jpoimboe@kernel.org
This commit is contained in:
Josh Poimboeuf
2025-12-02 09:59:36 -08:00
committed by Ingo Molnar
parent 0c314a881c
commit a818f28f01
3 changed files with 7 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
arch/um/include/shared/common-offsets.h
View File

@@ -18,3 +18,5 @@ DEFINE(UM_NSEC_PER_USEC, NSEC_PER_USEC);
DEFINE(UM_KERN_GDT_ENTRY_TLS_ENTRIES, GDT_ENTRY_TLS_ENTRIES);
DEFINE(UM_SECCOMP_ARCH_NATIVE, SECCOMP_ARCH_NATIVE);
DEFINE(ALT_INSTR_SIZE, sizeof(struct alt_instr));

7
arch/x86/include/asm/alternative.h
View File

@@ -197,8 +197,8 @@ static inline int alternatives_text_reserved(void *start, void *end)
"773:\n"
#define ALTINSTR_ENTRY(ft_flags) \
".pushsection .altinstructions,\"a\"\n" \
ANNOTATE_DATA_SPECIAL \
".pushsection .altinstructions, \"aM\", @progbits, " \
__stringify(ALT_INSTR_SIZE) "\n" \
" .long 771b - .\n" /* label */ \
" .long 774f - .\n" /* new instruction */ \
" .4byte " __stringify(ft_flags) "\n" /* feature + flags */ \
@@ -339,7 +339,6 @@ void nop_func(void);
* instruction. See apply_alternatives().
*/
.macro altinstr_entry orig alt ft_flags orig_len alt_len
ANNOTATE_DATA_SPECIAL
.long \orig - .
.long \alt - .
.4byte \ft_flags
@@ -363,7 +362,7 @@ void nop_func(void);
741: \
.skip -(((744f-743f)-(741b-740b)) > 0) * ((744f-743f)-(741b-740b)),0x90 ;\
742: \
.pushsection .altinstructions,"a" ; \
.pushsection .altinstructions, "aM", @progbits, ALT_INSTR_SIZE ;\
altinstr_entry 740b,743f,flag,742b-740b,744f-743f ; \
.popsection ; \
.pushsection .altinstr_replacement,"ax" ; \

2
arch/x86/kernel/asm-offsets.c
View File

@@ -124,4 +124,6 @@ static void __used common(void)
OFFSET(ARIA_CTX_rounds, aria_ctx, rounds);
#endif
BLANK();
DEFINE(ALT_INSTR_SIZE, sizeof(struct alt_instr));
}