Messages in this thread Patch in this message | | | From | Arnaldo Carvalho de Melo <> | Subject | [PATCH 1/1] perf kvm: Finding struct machine fails for PERF_RECORD_MMAP | Date | Wed, 11 Apr 2012 17:57:43 -0300 |
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From: "Nikunj A. Dadhania" <nikunj@linux.vnet.ibm.com>
Running 'perf kvm --host --guest --guestmount /tmp/guestmount record -a -g -- sleep 2'
Was resulting in a segfault. For event type PERF_RECORD_MMAP, event->ip.pid is being used in perf_session__find_machine_for_cpumode, which is not correct.
The event->ip.pid field happens to be 0 in this case and results in returning a NULL machine object. Finally, access to self->pid in machine__mmap_name, results in a segfault later.
For PERF_RECORD_MMAP type, pass event->mmap.pid.
Signed-off-by: Nikunj A. Dadhania <nikunj@linux.vnet.ibm.com> Reviewed-by: David Ahern <dsahern@gmail.com> Tested-by: David Ahern <dsahern@gmail.com> Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Stephane Eranian <eranian@google.com> Cc: Nikunj A. Dadhania <nikunj@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/20120409081835.10576.22018.stgit@abhimanyu.in.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> --- tools/perf/util/session.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c index 9412e3b..00923cd 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -826,8 +826,16 @@ static struct machine * { const u8 cpumode = event->header.misc & PERF_RECORD_MISC_CPUMODE_MASK; - if (cpumode == PERF_RECORD_MISC_GUEST_KERNEL && perf_guest) - return perf_session__find_machine(session, event->ip.pid); + if (cpumode == PERF_RECORD_MISC_GUEST_KERNEL && perf_guest) { + u32 pid; + + if (event->header.type == PERF_RECORD_MMAP) + pid = event->mmap.pid; + else + pid = event->ip.pid; + + return perf_session__find_machine(session, pid); + } return perf_session__find_host_machine(session); } -- 1.7.9.2.358.g22243
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