[Qemu-devel] [PULL for-2.0 0/1] Tracing patches

[Qemu-devel] [PULL for-2.0 0/1] Tracing patches

[Stefan Hajnoczi]

This SystemTap fix makes the .stp file we generate work again.

The following changes since commit 63678e17cf399ff81b93417fe7bee8d6ef6b6b1b:

  configure: add option to disable -fstack-protector flags (2014-03-31 20:16:02 +0100)

are available in the git repository at:

  git://github.com/stefanha/qemu.git tags/tracing-pull-request

for you to fetch changes up to 9bcec938aab22a1b7ced916a6895e5029d4ed04f:

  trace: add workaround for SystemTap PR13296 (2014-04-01 20:08:25 +0200)

----------------------------------------------------------------
Tracing pull request

----------------------------------------------------------------
Frank Ch. Eigler (1):
      trace: add workaround for SystemTap PR13296

 hw/intc/apic_common.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

-- 
1.9.0

[Qemu-devel] [PULL for-2.0 1/1] trace: add workaround for SystemTap PR13296

[Stefan Hajnoczi]

From: "Frank Ch. Eigler" <fche@redhat.com>

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>
---
 hw/intc/apic_common.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/hw/intc/apic_common.c b/hw/intc/apic_common.c
index c623fcc..7ecce2d 100644
--- a/hw/intc/apic_common.c
+++ b/hw/intc/apic_common.c
@@ -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;
 }
-- 
1.9.0

Re: [Qemu-devel] [PULL for-2.0 0/1] Tracing patches

[Peter Maydell]

On 1 April 2014 19:11, Stefan Hajnoczi <stefanha@redhat.com> wrote:
> This SystemTap fix makes the .stp file we generate work again.
>
> The following changes since commit 63678e17cf399ff81b93417fe7bee8d6ef6b6b1b:
>
>   configure: add option to disable -fstack-protector flags (2014-03-31 20:16:02 +0100)
>
> are available in the git repository at:
>
>   git://github.com/stefanha/qemu.git tags/tracing-pull-request
>
> for you to fetch changes up to 9bcec938aab22a1b7ced916a6895e5029d4ed04f:
>
>   trace: add workaround for SystemTap PR13296 (2014-04-01 20:08:25 +0200)

Applied, thanks. (That is a really ugly hack...)

-- PMM