Messages in this thread | | | Subject | Re: [PATCH] perf script: Fix overrun issue for dynamically-allocated pmu type number | From | "Jin, Yao" <> | Date | Wed, 2 Dec 2020 09:26:48 +0800 |
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Hi Adrian,
On 11/26/2020 10:47 PM, Jin, Yao wrote: > Hi Adrian, > > On 11/26/2020 4:36 PM, Adrian Hunter wrote: >> On 26/11/20 9:06 am, Jin, Yao wrote: >>> 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; >> >> That is a nop if attr->type != PERF_TYPE_SYNTH >> Given that PERF_TYPE_SYNTH is (INT_MAX + 1), it is a nop for all kernel >> dynamically allocated PMU numbers. >> >>> >>> 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. :) >> >> I think perf script has always had this problem. >> > > Since perf-script has always had this problem, I'm OK to remove the fixes tag from the patch > description. > > Thanks > Jin Yao
Can I get your ACK if the fixes tag is removed from this patch?
Do I need to post a new version which just removes the fixes tag?
Thanks Jin Yao
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