perf_counter, x86: Add mmap counter read support

Update the mmap control page with the needed information to
use the userspace RDPMC instruction for self monitoring.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 9 insertions, 0 deletions

diff --git a/arch/x86/include/asm/perf_counter.h b/arch/x86/include/asm/perf_counter.h
index 5fb33e160ea0..fa64e401589d 100644
--- a/arch/x86/include/asm/perf_counter.h
+++ b/arch/x86/include/asm/perf_counter.h
@@ -87,6 +87,9 @@ union cpuid10_edx {
 #ifdef CONFIG_PERF_COUNTERS
 extern void init_hw_perf_counters(void);
 extern void perf_counters_lapic_init(void);
+
+#define PERF_COUNTER_INDEX_OFFSET                       0
+
 #else
 static inline void init_hw_perf_counters(void)          { }
 static inline void perf_counters_lapic_init(void)       { }
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index a310d19faca3..b83474b6021a 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -912,6 +912,8 @@ x86_perf_counter_set_period(struct perf_counter *counter,
         err = checking_wrmsrl(hwc->counter_base + idx,
                              (u64)(-left) & x86_pmu.counter_mask);
 
+        perf_counter_update_userpage(counter);
+
         return ret;
 }
 
@@ -1034,6 +1036,8 @@ try_generic:
         x86_perf_counter_set_period(counter, hwc, idx);
         x86_pmu.enable(hwc, idx);
 
+        perf_counter_update_userpage(counter);
+
         return 0;
 }
 
@@ -1126,6 +1130,8 @@ static void x86_pmu_disable(struct perf_counter *counter)
         x86_perf_counter_update(counter, hwc, idx);
         cpuc->counters[idx] = NULL;
         clear_bit(idx, cpuc->used_mask);
+
+        perf_counter_update_userpage(counter);
 }
 
 /*