Hi Ingo, Ping?
On Wed, Mar 09, 2016 at 12:59:50PM -0600, Josh Poimboeuf wrote: > 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 <fengguang...@intel.com> > Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com> > --- > arch/x86/kvm/emulate.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c > index 0f62943..a2f24af 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); > -- > 2.4.3 > -- Josh
