With some configs, gcc doesn't inline test_cc(). When that happens, it
doesn't create a stack frame before inserting the call instruction.
This breaks frame pointer convention if CONFIG_FRAME_POINTER is enabled
and 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.
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Gleb Natapov <gleb@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: kvm@xxxxxxxxxxxxxxx
---
arch/x86/kvm/emulate.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index aa4d726..7dba65a 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -972,11 +972,13 @@ static int em_bsr_c(struct x86_emulate_ctxt *ctxt)
static u8 test_cc(unsigned int condition, unsigned long flags)
{
u8 rc;
+ register void *__sp asm(_ASM_SP);
void (*fop)(void) = (void *)em_setcc + 4 * (condition & 0xf);
flags = (flags & EFLAGS_MASK) | X86_EFLAGS_IF;
asm("push %[flags]; popf; call *%[fastop]"
- : "=a"(rc) : [fastop]"r"(fop), [flags]"r"(flags));
+ : "=a"(rc), "+r"(__sp)
+ : [fastop]"r"(fop), [flags]"r"(flags));
return rc;
}
--
2.4.3
--
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