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x86/asm: Annotate special section entries

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In preparation for the objtool klp diff subcommand, add annotations for
special section entries.  This will enable objtool to determine the size
and location of the entries and to extract them when needed.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
This commit is contained in:
Josh Poimboeuf 2025-09-17 09:03:55 -07:00
parent 58f36a5756
commit aca282ab7e
6 changed files with 15 additions and 1 deletions
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4
arch/x86/include/asm/alternative.h
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@ -198,6 +198,7 @@ static inline int alternatives_text_reserved(void *start, void *end)
#define ALTINSTR_ENTRY(ft_flags) \
".pushsection .altinstructions,\"a\"\n" \
ANNOTATE_DATA_SPECIAL \
" .long 771b - .\n" /* label */ \
" .long 774f - .\n" /* new instruction */ \
" .4byte " __stringify(ft_flags) "\n" /* feature + flags */ \
@ -207,6 +208,7 @@ static inline int alternatives_text_reserved(void *start, void *end)
#define ALTINSTR_REPLACEMENT(newinstr) /* replacement */ \
".pushsection .altinstr_replacement, \"ax\"\n" \
ANNOTATE_DATA_SPECIAL \
"# ALT: replacement\n" \
"774:\n\t" newinstr "\n775:\n" \
".popsection\n"
@ -337,6 +339,7 @@ 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
@ -365,6 +368,7 @@ void nop_func(void);
.popsection ; \
.pushsection .altinstr_replacement,"ax" ; \
743: \
ANNOTATE_DATA_SPECIAL ; \
newinst ; \
744: \
.popsection ;

5
arch/x86/include/asm/asm.h
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@ -2,6 +2,8 @@
#ifndef _ASM_X86_ASM_H
#define _ASM_X86_ASM_H
#include <linux/annotate.h>
#ifdef __ASSEMBLER__
# define __ASM_FORM(x, ...) x,## __VA_ARGS__
# define __ASM_FORM_RAW(x, ...) x,## __VA_ARGS__
@ -132,6 +134,7 @@ static __always_inline __pure void *rip_rel_ptr(void *p)
# define _ASM_EXTABLE_TYPE(from, to, type) \
.pushsection "__ex_table","a" ; \
.balign 4 ; \
ANNOTATE_DATA_SPECIAL ; \
.long (from) - . ; \
.long (to) - . ; \
.long type ; \
@ -179,6 +182,7 @@ static __always_inline __pure void *rip_rel_ptr(void *p)
# define _ASM_EXTABLE_TYPE(from, to, type) \
" .pushsection \"__ex_table\",\"a\"\n" \
" .balign 4\n" \
ANNOTATE_DATA_SPECIAL \
" .long (" #from ") - .\n" \
" .long (" #to ") - .\n" \
" .long " __stringify(type) " \n" \
@ -187,6 +191,7 @@ static __always_inline __pure void *rip_rel_ptr(void *p)
# define _ASM_EXTABLE_TYPE_REG(from, to, type, reg) \
" .pushsection \"__ex_table\",\"a\"\n" \
" .balign 4\n" \
ANNOTATE_DATA_SPECIAL \
" .long (" #from ") - .\n" \
" .long (" #to ") - .\n" \
DEFINE_EXTABLE_TYPE_REG \

1
arch/x86/include/asm/bug.h
View File

@ -57,6 +57,7 @@
#define _BUG_FLAGS_ASM(ins, file, line, flags, size, extra) \
"1:\t" ins "\n" \
".pushsection __bug_table,\"aw\"\n" \
ANNOTATE_DATA_SPECIAL \
__BUG_ENTRY(file, line, flags) \
"\t.org 2b + " size "\n" \
".popsection\n" \

1
arch/x86/include/asm/cpufeature.h
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@ -101,6 +101,7 @@ static __always_inline bool _static_cpu_has(u16 bit)
asm goto(ALTERNATIVE_TERNARY("jmp 6f", %c[feature], "", "jmp %l[t_no]")
".pushsection .altinstr_aux,\"ax\"\n"
"6:\n"
ANNOTATE_DATA_SPECIAL
" testb %[bitnum], %a[cap_byte]\n"
" jnz %l[t_yes]\n"
" jmp %l[t_no]\n"

1
arch/x86/include/asm/jump_label.h
View File

@ -15,6 +15,7 @@
#define JUMP_TABLE_ENTRY(key, label) \
".pushsection __jump_table, \"aw\" \n\t" \
_ASM_ALIGN "\n\t" \
ANNOTATE_DATA_SPECIAL \
".long 1b - . \n\t" \
".long " label " - . \n\t" \
_ASM_PTR " " key " - . \n\t" \

4
include/linux/objtool.h
View File

@ -9,9 +9,10 @@
#ifndef __ASSEMBLY__
#define UNWIND_HINT(type, sp_reg, sp_offset, signal) \
#define UNWIND_HINT(type, sp_reg, sp_offset, signal) \
"987: \n\t" \
".pushsection .discard.unwind_hints\n\t" \
ANNOTATE_DATA_SPECIAL \
/* struct unwind_hint */ \
".long 987b - .\n\t" \
".short " __stringify(sp_offset) "\n\t" \
@ -78,6 +79,7 @@
.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0
.Lhere_\@:
.pushsection .discard.unwind_hints
ANNOTATE_DATA_SPECIAL
/* struct unwind_hint */
.long .Lhere_\@ - .
.short \sp_offset