Messages in this thread | | | From | Vince Weaver <> | Date | Wed, 26 Jul 2017 15:39:01 -0400 (EDT) | Subject | perf: bug in rdpmc/mmap accounting after exec |
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Hello
so one last bug found by the PAPI testsuite.
This one involves the rdpmc auto-disable on last unmap of an event feature.
Failing test case:
fd=perf_event_open(); addr=mmap(fd); exec() // without closing or unmapping the event fd=perf_event_open(); addr=mmap(fd); rdpmc() // GPFs due to rdpmc being disabled
I won't pretend to be able to follow the rdpmc disabling code, but if I add some printks it looks like current->mm->context.perf_rdpmc_allowed isn't properly being reset on exec?
In fact, current->mm->context.perf_rdpmc_allowed goes negative which seems like it shouldn't happen?
Anyway, a test case for this can be found in the perf_event_tests, tests/rdpmc/rdpmc_exec_papi
Vince
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