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authorJiri Olsa <jolsa@kernel.org>2018-08-17 13:45:56 +0200
committerArnaldo Carvalho de Melo <acme@redhat.com>2018-08-20 08:54:59 -0300
commit721f0dfc3ce821c6a32820ab63edfb48ed4af075 (patch)
tree0cef3ac0e69c7b5e4406b0780bf98b2099c2c5e5 /tools/perf
parent31fb4c0d7b88f036edb96a6a3bd791289ea2f931 (diff)
perf python: Fix pyrf_evlist__read_on_cpu() interface
Jaroslav reported errors from valgrind over perf python script: # echo 0 > /sys/devices/system/cpu/cpu4/online # valgrind ./test.py ==7524== Memcheck, a memory error detector ... ==7524== Command: ./test.py ==7524== pid 7526 exited ==7524== Invalid read of size 8 ==7524== at 0xCC2C2B3: perf_mmap__read_forward (evlist.c:780) ==7524== by 0xCC2A681: pyrf_evlist__read_on_cpu (python.c:959) ... ==7524== Address 0x65c4868 is 16 bytes after a block of size 459,36.. ==7524== at 0x4C2B955: calloc (vg_replace_malloc.c:711) ==7524== by 0xCC2F484: zalloc (util.h:35) ==7524== by 0xCC2F484: perf_evlist__alloc_mmap (evlist.c:978) ... The reason for this is in the python interface, that allows a script to pass arbitrary cpu number, which is then used to access struct perf_evlist::mmap array. That's obviously wrong and works only when if all cpus are available and fails if some cpu is missing, like in the example above. This patch makes pyrf_evlist__read_on_cpu() search the evlist's maps array for the proper map to access. It's linear search at the moment. Based on the way how is the read_on_cpu used, I don't think we need to be fast in here. But we could add some hash in the middle to make it fast/er. We don't allow python interface to set write_backward event attribute, so it's safe to check only evlist's mmaps. Reported-by: Jaroslav Škarvada <jskarvad@redhat.com> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Joe Mario <jmario@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20180817114556.28000-3-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf')
-rw-r--r--tools/perf/util/python.c20
1 files changed, 19 insertions, 1 deletions
diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index f74fbb652a4f..ce501ba14b08 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -11,6 +11,7 @@
#include "cpumap.h"
#include "print_binary.h"
#include "thread_map.h"
+#include "mmap.h"
#if PY_MAJOR_VERSION < 3
#define _PyUnicode_FromString(arg) \
@@ -976,6 +977,20 @@ static PyObject *pyrf_evlist__add(struct pyrf_evlist *pevlist,
return Py_BuildValue("i", evlist->nr_entries);
}
+static struct perf_mmap *get_md(struct perf_evlist *evlist, int cpu)
+{
+ int i;
+
+ for (i = 0; i < evlist->nr_mmaps; i++) {
+ struct perf_mmap *md = &evlist->mmap[i];
+
+ if (md->cpu == cpu)
+ return md;
+ }
+
+ return NULL;
+}
+
static PyObject *pyrf_evlist__read_on_cpu(struct pyrf_evlist *pevlist,
PyObject *args, PyObject *kwargs)
{
@@ -990,7 +1005,10 @@ static PyObject *pyrf_evlist__read_on_cpu(struct pyrf_evlist *pevlist,
&cpu, &sample_id_all))
return NULL;
- md = &evlist->mmap[cpu];
+ md = get_md(evlist, cpu);
+ if (!md)
+ return NULL;
+
if (perf_mmap__read_init(md) < 0)
goto end;