performance counters: x86 support

Implement performance counters for x86 Intel CPUs.

It's simplified right now: the PERFMON CPU feature is assumed,
which is available in Core2 and later Intel CPUs.

The design is flexible to be extended to more CPU types as well.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 1 deletions

diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index b1cc6da64208..dee553c503d3 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -6,7 +6,7 @@
  *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
  *  2000-2002   x86-64 support by Andi Kleen
  */
-
+#include <linux/perf_counter.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
 #include <linux/smp.h>
@@ -891,6 +891,11 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
                 tracehook_notify_resume(regs);
         }
 
+        if (thread_info_flags & _TIF_PERF_COUNTERS) {
+                clear_thread_flag(TIF_PERF_COUNTERS);
+                perf_counter_notify(regs);
+        }
+
 #ifdef CONFIG_X86_32
         clear_thread_flag(TIF_IRET);
 #endif /* CONFIG_X86_32 */