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| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2016-03-09 12:59:50 -0600 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-05-10 18:16:50 +0200 |
| commit | 4548f63e65116458da5245d89aa213b4f8b2ab16 (patch) | |
| tree | 8a8de094e1c0052b87f2180398fd5e4f7b4af9e5 | |
| parent | 5e1b59abef69e405eabfbe0ad09ad6b6e5303c7d (diff) | |
| download | lwn-4548f63e65116458da5245d89aa213b4f8b2ab16.tar.gz lwn-4548f63e65116458da5245d89aa213b4f8b2ab16.zip | |
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 <fengguang.wu@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/emulate.c | 6 |
1 files changed, 5 insertions, 1 deletions
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); |