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
