On March 3, 2025 3:02:41 AM PST, tip-bot2 for Josh Poimboeuf <tip-bot2@xxxxxxxxxxxxx> wrote: >The following commit has been merged into the x86/asm branch of tip: > >Commit-ID: e5ff90b179d45df71373cf79f99d20c9abe229cb >Gitweb: https://git.kernel.org/tip/e5ff90b179d45df71373cf79f99d20c9abe229cb >Author: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> >AuthorDate: Sun, 02 Mar 2025 17:21:03 -08:00 >Committer: Ingo Molnar <mingo@xxxxxxxxxx> >CommitterDate: Mon, 03 Mar 2025 11:39:54 +01:00 > >x86/asm: Make ASM_CALL_CONSTRAINT conditional on frame pointers > >With frame pointers enabled, ASM_CALL_CONSTRAINT is used in an inline >asm statement with a call instruction to force the compiler to set up >the frame pointer before doing the call. > >Without frame pointers, no such constraint is needed. Make it >conditional on frame pointers. > >Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> >Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> >Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> >Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> >Cc: Brian Gerst <brgerst@xxxxxxxxx> >Cc: H. Peter Anvin <hpa@xxxxxxxxx> >Cc: linux-kernel@xxxxxxxxxxxxxxx >--- > arch/x86/include/asm/asm.h | 4 ++++ > 1 file changed, 4 insertions(+) > >diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h >index 0d268e6..f1db9e8 100644 >--- a/arch/x86/include/asm/asm.h >+++ b/arch/x86/include/asm/asm.h >@@ -232,7 +232,11 @@ register unsigned long current_stack_pointer asm(_ASM_SP); > * gets set up by the containing function. If you forget to do this, objtool > * may print a "call without frame pointer save/setup" warning. > */ >+#ifdef CONFIG_UNWINDER_FRAME_POINTER > #define ASM_CALL_CONSTRAINT "r" (__builtin_frame_address(0)) >+#else >+#define ASM_CALL_CONSTRAINT >+#endif > > #endif /* __ASSEMBLY__ */ > Wait, why was this changed? I actually tested this form at least once and found that it didn't work under all circumstances...
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