perf: Fix mmap_page capabilities and docs

Complete the syscall-less self-profiling feature and address
all complaints, namely:

 - capabilities, so we can detect what is actually available at runtime

     Add a capabilities field to perf_event_mmap_page to indicate
     what is actually available for use.

 - on x86: RDPMC weirdness due to being 40/48 bits and not sign-extending
   properly.

 - ABI documentation as to how all this stuff works.

Also improve the documentation for the new features.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vweaver1@eecs.utk.edu>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1332433596.2487.33.camel@twins
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index c61234b1a988..dc3b05272511 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3348,7 +3348,7 @@ static void calc_timer_values(struct perf_event *event,
         *running = ctx_time - event->tstamp_running;
 }
 
-void __weak perf_update_user_clock(struct perf_event_mmap_page *userpg, u64 now)
+void __weak arch_perf_update_userpage(struct perf_event_mmap_page *userpg, u64 now)
 {
 }
 
@@ -3398,7 +3398,7 @@ void perf_event_update_userpage(struct perf_event *event)
         userpg->time_running = running +
                         atomic64_read(&event->child_total_time_running);
 
-        perf_update_user_clock(userpg, now);
+        arch_perf_update_userpage(userpg, now);
 
         barrier();
         ++userpg->lock;