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author | Paul Mackerras <paulus@samba.org> | 2009-02-09 12:42:47 +0100 |
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committer | Ingo Molnar <mingo@elte.hu> | 2009-02-09 12:47:16 +0100 |
commit | 23a185ca8abbeef64b6ffc33059b1d630e43ec10 (patch) | |
tree | c5eb9454ff969377adb40532119240f6fc893fcb /arch/powerpc/kernel/perf_counter.c | |
parent | perfcounters: fix "perf counters kills oprofile" bug, v2 (diff) | |
download | linux-23a185ca8abbeef64b6ffc33059b1d630e43ec10.tar.xz linux-23a185ca8abbeef64b6ffc33059b1d630e43ec10.zip |
perf_counters: make software counters work as per-cpu counters
Impact: kernel crash fix
Yanmin Zhang reported that using a PERF_COUNT_TASK_CLOCK software
counter as a per-cpu counter would reliably crash the system, because
it calls __task_delta_exec with a null pointer. The page fault,
context switch and cpu migration counters also won't function
correctly as per-cpu counters since they reference the current task.
This fixes the problem by redirecting the task_clock counter to the
cpu_clock counter when used as a per-cpu counter, and by implementing
per-cpu page fault, context switch and cpu migration counters.
Along the way, this:
- Initializes counter->ctx earlier, in perf_counter_alloc, so that
sw_perf_counter_init can use it
- Adds code to kernel/sched.c to count task migrations into each
cpu, in rq->nr_migrations_in
- Exports the per-cpu context switch and task migration counts
via new functions added to kernel/sched.c
- Makes sure that if sw_perf_counter_init fails, we don't try to
initialize the counter as a hardware counter. Since the user has
passed a negative, non-raw event type, they clearly don't intend
for it to be interpreted as a hardware event.
Reported-by: "Zhang Yanmin" <yanmin_zhang@linux.intel.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/powerpc/kernel/perf_counter.c')
0 files changed, 0 insertions, 0 deletions