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trace: add workaround for SystemTap PR13296

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SystemTap sdt.h sometimes results in compiled probes without sufficient
information to extract arguments.  This can be solved in a slightly
hacky way by encouraging the compiler to place arguments into registers.

This patch fixes the apic_reset_irq_delivered() trace event on Fedora 20
with gcc-4.8.2-7.fc20 and systemtap-sdt-devel-2.4-2.fc20 on x86_64.

Signed-off-by: Frank Ch. Eigler <fche@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Frank Ch. Eigler 2014-03-25 13:08:30 +01:00 committed by Stefan Hajnoczi
parent 63678e17cf
commit 9bcec938aa
1 changed files with 6 additions and 1 deletions
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7
hw/intc/apic_common.c
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@ -117,7 +117,12 @@ void apic_report_irq_delivered(int delivered)
void apic_reset_irq_delivered(void)
{
trace_apic_reset_irq_delivered(apic_irq_delivered);
/* Copy this into a local variable to encourage gcc to emit a plain
* register for a sys/sdt.h marker. For details on this workaround, see:
* https://sourceware.org/bugzilla/show_bug.cgi?id=13296
*/
volatile int a_i_d = apic_irq_delivered;
trace_apic_reset_irq_delivered(a_i_d);
apic_irq_delivered = 0;
}