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authorCyrill Gorcunov <gorcunov@gmail.com>2010-05-14 23:08:15 +0400
committerIngo Molnar <mingo@elte.hu>2010-05-15 08:38:55 +0200
commit1ff3d7d79204612ebe2e611d2592f8898908ca00 (patch)
tree666a907c25cc9ebeff05dfe982b5d480f42f64ad /arch
parent5d2be7cb198a0a6bc6088d3806fb7261b184ad89 (diff)
x86, perf: P4 PMU - fix counters management logic
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/perf_event_p4.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c
index cb875b1e2e8..424fc8de68e 100644
--- a/arch/x86/kernel/cpu/perf_event_p4.c
+++ b/arch/x86/kernel/cpu/perf_event_p4.c
@@ -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;
}