perf, x86: P4 PMU -- do a real check for ESCR address being in hash

To prevent from clashes in future code modifications
do a real check for ESCR address being in hash. At
moment the callers are known to pass sane values but
better to be on a safe side.

And comment fix.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
CC: Lin Ming <ming.m.lin@intel.com>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100518212439.004503600@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 4 insertions, 3 deletions

diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c
index 87e1803e67a6..5f8e36d62793 100644
--- a/arch/x86/kernel/cpu/perf_event_p4.c
+++ b/arch/x86/kernel/cpu/perf_event_p4.c
@@ -670,7 +670,7 @@ static void p4_pmu_swap_config_ts(struct hw_perf_event *hwc, int cpu)
 
 /*
  * ESCR address hashing is tricky, ESCRs are not sequential
- * in memory but all starts from MSR_P4_BSU_ESCR0 (0x03e0) and
+ * in memory but all starts from MSR_P4_BSU_ESCR0 (0x03a0) and
  * the metric between any ESCRs is laid in range [0xa0,0xe1]
  *
  * so we make ~70% filled hashtable
@@ -735,8 +735,9 @@ static int p4_get_escr_idx(unsigned int addr)
 {
         unsigned int idx = P4_ESCR_MSR_IDX(addr);
 
-        if (unlikely(idx >= P4_ESCR_MSR_TABLE_SIZE ||
-                        !p4_escr_table[idx])) {
+        if (unlikely(idx >= P4_ESCR_MSR_TABLE_SIZE      ||
+                        !p4_escr_table[idx]             ||
+                        p4_escr_table[idx] != addr)) {
                 WARN_ONCE(1, "P4 PMU: Wrong address passed: %x\n", addr);
                 return -1;
         }