In preparation for the objtool klp diff subcommand, define the entry size for the .altinstructions section in its ELF header. This will allow tooling to extract individual entries.
Signed-off-by: Josh Poimboeuf <[email protected]> --- arch/x86/include/asm/alternative.h | 7 +++++-- arch/x86/kernel/alternative.c | 2 ++ 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h index e18cdaa1573c..212761eec886 100644 --- a/arch/x86/include/asm/alternative.h +++ b/arch/x86/include/asm/alternative.h @@ -15,6 +15,8 @@ #define ALT_DIRECT_CALL(feature) ((ALT_FLAG_DIRECT_CALL << ALT_FLAGS_SHIFT) | (feature)) #define ALT_CALL_ALWAYS ALT_DIRECT_CALL(X86_FEATURE_ALWAYS) +#define ALTINSTR_SIZE 14 + #ifndef __ASSEMBLER__ #include <linux/stddef.h> @@ -165,7 +167,8 @@ static inline int alternatives_text_reserved(void *start, void *end) "773:\n" #define ALTINSTR_ENTRY(ft_flags) \ - ".pushsection .altinstructions,\"a\"\n" \ + ".pushsection .altinstructions, \"aM\", @progbits, " \ + __stringify(ALTINSTR_SIZE) "\n" \ " .long 771b - .\n" /* label */ \ " .long 774f - .\n" /* new instruction */ \ " .4byte " __stringify(ft_flags) "\n" /* feature + flags */ \ @@ -328,7 +331,7 @@ void nop_func(void); 741: \ .skip -(((744f-743f)-(741b-740b)) > 0) * ((744f-743f)-(741b-740b)),0x90 ;\ 742: \ - .pushsection .altinstructions,"a" ; \ + .pushsection .altinstructions, "aM", @progbits, ALTINSTR_SIZE ; \ altinstr_entry 740b,743f,flag,742b-740b,744f-743f ; \ .popsection ; \ .pushsection .altinstr_replacement,"ax" ; \ diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index ec220e53cb52..d6064dd87dde 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -425,6 +425,8 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start, u8 *instr, *replacement; struct alt_instr *a, *b; + BUILD_BUG_ON(ALTINSTR_SIZE != sizeof(struct alt_instr)); + DPRINTK(ALT, "alt table %px, -> %px", start, end); /* -- 2.49.0
