[PATCH v2] perf script: Fix overrun issue for dynamically-allocated pmu type number

From: Jin Yao
Date: Tue Dec 08 2020 - 20:01:35 EST


When unpacking the event which is from dynamic pmu, the array
output[OUTPUT_TYPE_MAX] may be overrun. For example, type number of
SKL uncore_imc is 10, but OUTPUT_TYPE_MAX is 7 now (OUTPUT_TYPE_MAX =
PERF_TYPE_MAX + 1).

/* In builtin-script.c */
process_event()
{
unsigned int type = output_type(attr->type);

if (output[type].fields == 0)
return;
}

output[10] is overrun.

Create a type OUTPUT_TYPE_OTHER for dynamic pmu events, then
output_type(attr->type) will return OUTPUT_TYPE_OTHER here.

Note that if PERF_TYPE_MAX ever changed, then there would be a conflict
between old perf.data files that had a dynamicaliy allocated PMU number
that would then be the same as a fixed PERF_TYPE.

Example:

perf record --switch-events -C 0 -e "{cpu-clock,uncore_imc/data_reads/,uncore_imc/data_writes/}:SD" -a -- sleep 1
perf script

Before:
swapper 0 [000] 1479253.987551: 277766 cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.987797: 246709 cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.988127: 329883 cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.988273: 146393 cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.988523: 249977 cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.988877: 354090 cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.989023: 145940 cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.989383: 359856 cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1479253.989523: 140082 cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])

After:
swapper 0 [000] 1397040.402011: 272384 cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1397040.402011: 5396 uncore_imc/data_reads/:
swapper 0 [000] 1397040.402011: 967 uncore_imc/data_writes/:
swapper 0 [000] 1397040.402259: 249153 cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1397040.402259: 7231 uncore_imc/data_reads/:
swapper 0 [000] 1397040.402259: 1297 uncore_imc/data_writes/:
swapper 0 [000] 1397040.402508: 249108 cpu-clock: ffffffff9d4ddb6f cpuidle_enter_state+0xdf ([kernel.kallsyms])
swapper 0 [000] 1397040.402508: 5333 uncore_imc/data_reads/:
swapper 0 [000] 1397040.402508: 1008 uncore_imc/data_writes/:

Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
---
v2:
Remove Fixes tag because this issue has always been here, not caused by
1405720d4f26 ("perf script: Add 'synth' event type for synthesized events").
No functional change in v2.

tools/perf/builtin-script.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 1c322c129185..5d8a64836228 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -183,6 +183,7 @@ struct output_option {

enum {
OUTPUT_TYPE_SYNTH = PERF_TYPE_MAX,
+ OUTPUT_TYPE_OTHER,
OUTPUT_TYPE_MAX
};

@@ -279,6 +280,18 @@ static struct {

.invalid_fields = PERF_OUTPUT_TRACE | PERF_OUTPUT_BPF_OUTPUT,
},
+
+ [OUTPUT_TYPE_OTHER] = {
+ .user_set = false,
+
+ .fields = PERF_OUTPUT_COMM | PERF_OUTPUT_TID |
+ PERF_OUTPUT_CPU | PERF_OUTPUT_TIME |
+ PERF_OUTPUT_EVNAME | PERF_OUTPUT_IP |
+ PERF_OUTPUT_SYM | PERF_OUTPUT_SYMOFFSET |
+ PERF_OUTPUT_DSO | PERF_OUTPUT_PERIOD,
+
+ .invalid_fields = PERF_OUTPUT_TRACE | PERF_OUTPUT_BPF_OUTPUT,
+ },
};

struct evsel_script {
@@ -339,8 +352,11 @@ static inline int output_type(unsigned int type)
case PERF_TYPE_SYNTH:
return OUTPUT_TYPE_SYNTH;
default:
- return type;
+ if (type < PERF_TYPE_MAX)
+ return type;
}
+
+ return OUTPUT_TYPE_OTHER;
}

static inline unsigned int attr_type(unsigned int type)
--
2.17.1