From: Josh Poimboeuf Date: Wed, 9 Mar 2016 18:59:50 +0000 (-0600) Subject: x86/kvm: Add stack frame dependency to fastop() inline asm X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=4548f63e65116458da5245d89aa213b4f8b2ab16;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git x86/kvm: Add stack frame dependency to fastop() inline asm The kbuild test robot reported this objtool warning [1]: arch/x86/kvm/emulate.o: warning: objtool: fastop()+0x69: call without frame pointer save/setup The issue seems to be caused by CONFIG_PROFILE_ALL_BRANCHES. With that option, for some reason gcc decides not to create a stack frame in fastop() before doing the inline asm call, which can result in a bad stack trace. Force a stack frame to be created if CONFIG_FRAME_POINTER is enabled by listing the stack pointer as an output operand for the inline asm statement. This change has no effect for !CONFIG_PROFILE_ALL_BRANCHES. [1] https://lists.01.org/pipermail/kbuild-all/2016-March/018249.html Reported-by: kbuild test robot Signed-off-by: Josh Poimboeuf Acked-by: Ingo Molnar Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 0f6294376fbd..a2f24af3c999 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -5110,13 +5110,17 @@ static void fetch_possible_mmx_operand(struct x86_emulate_ctxt *ctxt, static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *)) { + register void *__sp asm(_ASM_SP); ulong flags = (ctxt->eflags & EFLAGS_MASK) | X86_EFLAGS_IF; + if (!(ctxt->d & ByteOp)) fop += __ffs(ctxt->dst.bytes) * FASTOP_SIZE; + asm("push %[flags]; popf; call *%[fastop]; pushf; pop %[flags]\n" : "+a"(ctxt->dst.val), "+d"(ctxt->src.val), [flags]"+D"(flags), - [fastop]"+S"(fop) + [fastop]"+S"(fop), "+r"(__sp) : "c"(ctxt->src2.val)); + ctxt->eflags = (ctxt->eflags & ~EFLAGS_MASK) | (flags & EFLAGS_MASK); if (!fop) /* exception is returned in fop variable */ return emulate_de(ctxt);