Messages in this thread | | | Subject | Re: [PATCH] perf script: Fix overrun issue for dynamically-allocated pmu type number | From | "Jin, Yao" <> | Date | Thu, 26 Nov 2020 15:06:53 +0800 |
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Hi Adrian,
On 11/26/2020 2:51 PM, Adrian Hunter wrote: > On 26/11/20 5:24 am, Jin Yao wrote: >> 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/: >> >> Fixes: 1405720d4f26 ("perf script: Add 'synth' event type for synthesized events") > > It does not look to me like the problem was introduced by that commit. Are > you sure this Fixes tag is correct? >
Commit 1405720d4f26 added the change:
@@ -1215,8 +1253,9 @@ static void process_event(struct perf_script *script, { struct thread *thread = al->thread; struct perf_event_attr *attr = &evsel->attr; + unsigned int type = output_type(attr->type);
- if (output[attr->type].fields == 0) + if (output[type].fields == 0) return;
But of course, we can also say the original "output[attr->type].fields" introduced the issue, I'm not sure. Maybe Arnaldo can help to make the decision. :)
Thanks Jin Yao
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