The following commit has been merged into the x86/alternatives branch of tip:
Commit-ID: e208b3c4a9748b2c17aa09ba663b5096ccf82dce Gitweb: https://git.kernel.org/tip/e208b3c4a9748b2c17aa09ba663b5096ccf82dce Author: Juergen Gross <jgr...@suse.com> AuthorDate: Thu, 11 Mar 2021 15:23:11 +01:00 Committer: Borislav Petkov <b...@suse.de> CommitterDate: Thu, 11 Mar 2021 16:57:31 +01:00 x86/alternative: Support ALTERNATIVE_TERNARY Add ALTERNATIVE_TERNARY support for replacing an initial instruction with either of two instructions depending on a feature: ALTERNATIVE_TERNARY "default_instr", FEATURE_NR, "feature_on_instr", "feature_off_instr" which will start with "default_instr" and at patch time will, depending on FEATURE_NR being set or not, patch that with either "feature_on_instr" or "feature_off_instr". [ bp: Add comment ontop. ] Signed-off-by: Juergen Gross <jgr...@suse.com> Signed-off-by: Borislav Petkov <b...@suse.de> Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org> Link: https://lkml.kernel.org/r/20210311142319.4723-7-jgr...@suse.com --- arch/x86/include/asm/alternative.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h index 649e56f..17b3609 100644 --- a/arch/x86/include/asm/alternative.h +++ b/arch/x86/include/asm/alternative.h @@ -179,6 +179,11 @@ static inline int alternatives_text_reserved(void *start, void *end) ALTINSTR_REPLACEMENT(newinstr2, 2) \ ".popsection\n" +/* If @feature is set, patch in @newinstr_yes, otherwise @newinstr_no. */ +#define ALTERNATIVE_TERNARY(oldinstr, feature, newinstr_yes, newinstr_no) \ + ALTERNATIVE_2(oldinstr, newinstr_no, X86_FEATURE_ALWAYS, \ + newinstr_yes, feature) + #define ALTERNATIVE_3(oldinsn, newinsn1, feat1, newinsn2, feat2, newinsn3, feat3) \ OLDINSTR_3(oldinsn, 1, 2, 3) \ ".pushsection .altinstructions,\"a\"\n" \ @@ -210,6 +215,9 @@ static inline int alternatives_text_reserved(void *start, void *end) #define alternative_2(oldinstr, newinstr1, feature1, newinstr2, feature2) \ asm_inline volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2) ::: "memory") +#define alternative_ternary(oldinstr, feature, newinstr_yes, newinstr_no) \ + asm_inline volatile(ALTERNATIVE_TERNARY(oldinstr, feature, newinstr_yes, newinstr_no) ::: "memory") + /* * Alternative inline assembly with input. * @@ -380,6 +388,11 @@ static inline int alternatives_text_reserved(void *start, void *end) .popsection .endm +/* If @feature is set, patch in @newinstr_yes, otherwise @newinstr_no. */ +#define ALTERNATIVE_TERNARY(oldinstr, feature, newinstr_yes, newinstr_no) \ + ALTERNATIVE_2 oldinstr, newinstr_no, X86_FEATURE_ALWAYS, \ + newinstr_yes, feature + #endif /* __ASSEMBLY__ */ #endif /* _ASM_X86_ALTERNATIVE_H */
