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x86, perf: P4 PMU - fix counters management logic

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Jaswinder reported this #GP:

 |
 | Message from syslogd@ht at May 14 09:39:32 ...
 | kernel:[  314.908612] EIP: [<c100ccca>]
 | x86_perf_event_set_period+0x19d/0x1b2 SS:ESP 0068:edac3d70
 |

Ming has narrowed it down to a comparision issue
between arguments with different sizes and
signs. As result event index reached a wrong
value which in turn led to a GP fault.

At the same time it was found that p4_next_cntr
has broken logic and should return the counter
index only if it was not yet borrowed for
another event.

Reported-by: Jaswinder Singh Rajput <jaswinderlinux@gmail.com>
Reported-by: Lin Ming <ming.m.lin@intel.com>
Bisected-by: Lin Ming <ming.m.lin@intel.com>
Tested-by: Jaswinder Singh Rajput <jaswinderlinux@gmail.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100514190815.GG13509@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Cyrill Gorcunov 2010-05-14 23:08:15 +04:00 committed by Ingo Molnar
parent 5d2be7cb19
commit 1ff3d7d792
1 changed files with 4 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/x86/kernel/cpu/perf_event_p4.c
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@ -18,7 +18,7 @@
struct p4_event_bind {
unsigned int opcode; /* Event code and ESCR selector */
unsigned int escr_msr[2]; /* ESCR MSR for this event */
unsigned char cntr[2][P4_CNTR_LIMIT]; /* counter index (offset), -1 on abscence */
char cntr[2][P4_CNTR_LIMIT]; /* counter index (offset), -1 on abscence */
};
struct p4_cache_event_bind {
@ -747,11 +747,11 @@ static int p4_get_escr_idx(unsigned int addr)
static int p4_next_cntr(int thread, unsigned long *used_mask,
struct p4_event_bind *bind)
{
int i = 0, j;
int i, j;
for (i = 0; i < P4_CNTR_LIMIT; i++) {
j = bind->cntr[thread][i++];
if (j == -1 || !test_bit(j, used_mask))
j = bind->cntr[thread][i];
if (j != -1 && !test_bit(j, used_mask))
return j;
}