* [PATCH] perf script: Fix obtaining next event
@ 2019-10-30 8:40 Chandan Rajendra
2019-10-30 9:46 ` Ravi Bangoria
0 siblings, 1 reply; 3+ messages in thread
From: Chandan Rajendra @ 2019-10-30 8:40 UTC (permalink / raw)
To: linux-kernel
Cc: Chandan Rajendra, ravi.bangoria, peterz, mingo, acme,
mark.rutland, alexander.shishkin, jolsa, namhyung, rostedt,
tstoyanov, gregkh, kstewart, tglx, chandan
The current code segfaults when perf.data file contains two or more
events. This happens due to incorrect pointer arithmetic being performed
in trace_find_next_event().
tep_handle->events is an array of pointers to 'struct tep_event'. The
pointer arithmetic interprets tep_handle->events as an array of 'struct
tep_event' elements.
This commit replaces the usage of pointer arithmetic with calls to
tep_get_event().
Fixes: bb3dd7e ("tools lib traceevent, perf tools: Move struct tep_handler definition in a local header file")
Signed-off-by: Chandan Rajendra <chandanrlinux@gmail.com>
---
tools/perf/util/trace-event-parse.c | 24 +++++++-----------------
1 file changed, 7 insertions(+), 17 deletions(-)
diff --git a/tools/perf/util/trace-event-parse.c b/tools/perf/util/trace-event-parse.c
index 5d6bfc70b210..7bf423a3631e 100644
--- a/tools/perf/util/trace-event-parse.c
+++ b/tools/perf/util/trace-event-parse.c
@@ -176,31 +176,21 @@ int parse_event_file(struct tep_handle *pevent,
struct tep_event *trace_find_next_event(struct tep_handle *pevent,
struct tep_event *event)
{
- static int idx;
+ int idx;
int events_count;
- struct tep_event *all_events;
- all_events = tep_get_first_event(pevent);
events_count = tep_get_events_count(pevent);
- if (!pevent || !all_events || events_count < 1)
+ if (!pevent || events_count < 1)
return NULL;
- if (!event) {
- idx = 0;
- return all_events;
- }
+ if (!event)
+ return tep_get_event(pevent, 0);
- if (idx < events_count && event == (all_events + idx)) {
- idx++;
- if (idx == events_count)
- return NULL;
- return (all_events + idx);
+ for (idx = 0; idx < events_count - 1; idx++) {
+ if (event == tep_get_event(pevent, idx))
+ return tep_get_event(pevent, idx + 1);
}
- for (idx = 1; idx < events_count; idx++) {
- if (event == (all_events + (idx - 1)))
- return (all_events + idx);
- }
return NULL;
}
--
2.19.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] perf script: Fix obtaining next event
2019-10-30 8:40 [PATCH] perf script: Fix obtaining next event Chandan Rajendra
@ 2019-10-30 9:46 ` Ravi Bangoria
2019-10-30 11:50 ` Arnaldo Carvalho de Melo
0 siblings, 1 reply; 3+ messages in thread
From: Ravi Bangoria @ 2019-10-30 9:46 UTC (permalink / raw)
To: Chandan Rajendra, acme
Cc: linux-kernel, peterz, mingo, mark.rutland, alexander.shishkin,
jolsa, namhyung, rostedt, tstoyanov, gregkh, kstewart, tglx,
chandan, Ravi Bangoria
On 10/30/19 2:10 PM, Chandan Rajendra wrote:
> The current code segfaults when perf.data file contains two or more
> events. This happens due to incorrect pointer arithmetic being performed
> in trace_find_next_event().
>
> tep_handle->events is an array of pointers to 'struct tep_event'. The
> pointer arithmetic interprets tep_handle->events as an array of 'struct
> tep_event' elements.
>
> This commit replaces the usage of pointer arithmetic with calls to
> tep_get_event().
>
> Fixes: bb3dd7e ("tools lib traceevent, perf tools: Move struct tep_handler definition in a local header file")
> Signed-off-by: Chandan Rajendra <chandanrlinux@gmail.com>
$ sudo ./perf record -e sched:sched_switch -e syscalls:sys_enter_openat -- make
Without patch:
$ sudo ./perf script -g python
Segmentation fault
With patch:
$ sudo ./perf script -g python
generated Python script: perf-script.py
Reviewed-and-tested-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] perf script: Fix obtaining next event
2019-10-30 9:46 ` Ravi Bangoria
@ 2019-10-30 11:50 ` Arnaldo Carvalho de Melo
0 siblings, 0 replies; 3+ messages in thread
From: Arnaldo Carvalho de Melo @ 2019-10-30 11:50 UTC (permalink / raw)
To: Ravi Bangoria
Cc: Chandan Rajendra, linux-kernel, peterz, mingo, mark.rutland,
alexander.shishkin, jolsa, namhyung, rostedt, tstoyanov, gregkh,
kstewart, tglx, chandan
Em Wed, Oct 30, 2019 at 03:16:10PM +0530, Ravi Bangoria escreveu:
>
>
> On 10/30/19 2:10 PM, Chandan Rajendra wrote:
> > The current code segfaults when perf.data file contains two or more
> > events. This happens due to incorrect pointer arithmetic being performed
> > in trace_find_next_event().
> >
> > tep_handle->events is an array of pointers to 'struct tep_event'. The
> > pointer arithmetic interprets tep_handle->events as an array of 'struct
> > tep_event' elements.
> >
> > This commit replaces the usage of pointer arithmetic with calls to
> > tep_get_event().
> >
> > Fixes: bb3dd7e ("tools lib traceevent, perf tools: Move struct tep_handler definition in a local header file")
> > Signed-off-by: Chandan Rajendra <chandanrlinux@gmail.com>
>
> $ sudo ./perf record -e sched:sched_switch -e syscalls:sys_enter_openat -- make
>
> Without patch:
> $ sudo ./perf script -g python
> Segmentation fault
>
> With patch:
> $ sudo ./perf script -g python
> generated Python script: perf-script.py
>
> Reviewed-and-tested-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
This was fixed already in perf/core, by Steven:
commit 9bdff5b6436655d42dd30253c521e86ce07b9961
Author: Steven Rostedt (VMware) <rostedt@goodmis.org>
Date: Thu Oct 17 17:05:23 2019 -0400
perf tools: Remove unused trace_find_next_event()
trace_find_next_event() was buggy and pretty much a useless helper. As
there are no more users, just remove it.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Tzvetomir Stoyanov <tstoyanov@vmware.com>
Cc: linux-trace-devel@vger.kernel.org
Link: http://lore.kernel.org/lkml/20191017210636.224045576@goodmis.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
commit a5e05abc6b8d81148b35cd8632a4a6252383d968
Author: Steven Rostedt (VMware) <rostedt@goodmis.org>
Date: Thu Oct 17 17:05:22 2019 -0400
perf scripting engines: Iterate on tep event arrays directly
Instead of calling a useless (and broken) helper function to get the
next event of a tep event array, just get the array directly and iterate
over it.
Note, the broken part was from trace_find_next_event() which after this
will no longer be used, and can be removed.
Committer notes:
This fixes a segfault when generating python scripts from perf.data
files with multiple tracepoint events, i.e. the following use case is
fixed by this patch:
# perf record -e sched:* sleep 1
[ perf record: Woken up 31 times to write data ]
[ perf record: Captured and wrote 0.031 MB perf.data (9 samples) ]
# perf script -g python
Segmentation fault (core dumped)
#
Reported-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Tzvetomir Stoyanov <tstoyanov@vmware.com>
Cc: linux-trace-devel@vger.kernel.org
Link: http://lkml.kernel.org/r/20191017153733.630cd5eb@gandalf.local.home
Link: http://lore.kernel.org/lkml/20191017210636.061448713@goodmis.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-10-30 9:46 ` Ravi Bangoria
2019-10-30 11:50 ` Arnaldo Carvalho de Melo
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