Messages in this thread Patch in this message | | | From | Rusty Russell <> | Subject | Re: lguest: bug in lg_irq_enable? | Date | Mon, 02 Mar 2015 10:44:55 +1030 |
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Denys Vlasenko <vda.linux@googlemail.com> writes: > ENTRY(lg_irq_enable) > /* > * The reverse of irq_disable, this sets lguest_data.irq_enabled to > * X86_EFLAGS_IF (ie. "Interrupts enabled"). > */ > movl $X86_EFLAGS_IF, lguest_data+LGUEST_DATA_irq_enabled > /* > * But now we need to check if the Host wants to know: there might have > * been interrupts waiting to be delivered, in which case it will have > * set lguest_data.irq_pending to X86_EFLAGS_IF. If it's not zero, we > * jump to send_interrupts, otherwise we're done. > */ > testl $0, lguest_data+LGUEST_DATA_irq_pending > ^^^^^^^^^^^^^^^^^??????????
Heh, that should be cmpl! Nice catch!
Cheers, Rusty.
Subject: lguest: fix pending interrupt test.
Denys says: TEST with zero will always set ZF. Thus, "jnz send_interrupts" never jumps.
We get interrupts regularly enough that this didn't cause immediate problems.
Reported-by: Denys Vlasenko <vda.linux@googlemail.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/arch/x86/lguest/head_32.S b/arch/x86/lguest/head_32.S index 6ddfe4fc23c3..05b0a85507ce 100644 --- a/arch/x86/lguest/head_32.S +++ b/arch/x86/lguest/head_32.S @@ -84,7 +84,7 @@ ENTRY(lg_irq_enable) * set lguest_data.irq_pending to X86_EFLAGS_IF. If it's not zero, we * jump to send_interrupts, otherwise we're done. */ - testl $0, lguest_data+LGUEST_DATA_irq_pending + cmpl $0, lguest_data+LGUEST_DATA_irq_pending jnz send_interrupts /* * One cool thing about x86 is that you can do many things without using
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