| Message ID | 1456967378-6367-5-git-send-email-pfeiner@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 03/03/2016 02:09, Peter Feiner wrote: > With optimizations disabled, the compiler generated a call for > irq_enable() -- rather than just inlining an sti instruction as > expected. Thus the irq_enable ret would run in the sti shadow and the > vectors would fire in the wrong order. > > Signed-off-by: Peter Feiner <pfeiner@google.com> > --- > x86/eventinj.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/x86/eventinj.c b/x86/eventinj.c > index bddedce..202ac19 100644 > --- a/x86/eventinj.c > +++ b/x86/eventinj.c > @@ -296,8 +296,7 @@ int main() > apic_self_ipi(32); > flush_stack(); > io_delay(); > - irq_enable(); > - asm volatile ("int $33"); > + asm volatile ("sti; int $33"); > irq_disable(); > printf("After vec 32 and int $33\n"); > report("vec 32/int $33", test_count == 2); > I've added a comment to irq_enable too: /* Note that irq_enable() does not ensure an interrupt shadow due * to the vagaries of compiler optimizations. If you need the * shadow, use a single asm with "sti" and the instruction after it. */ Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/x86/eventinj.c b/x86/eventinj.c index bddedce..202ac19 100644 --- a/x86/eventinj.c +++ b/x86/eventinj.c @@ -296,8 +296,7 @@ int main() apic_self_ipi(32); flush_stack(); io_delay(); - irq_enable(); - asm volatile ("int $33"); + asm volatile ("sti; int $33"); irq_disable(); printf("After vec 32 and int $33\n"); report("vec 32/int $33", test_count == 2);
With optimizations disabled, the compiler generated a call for irq_enable() -- rather than just inlining an sti instruction as expected. Thus the irq_enable ret would run in the sti shadow and the vectors would fire in the wrong order. Signed-off-by: Peter Feiner <pfeiner@google.com> --- x86/eventinj.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)