perf_counter: provide generic callchain bits

Provide the generic callchain support bits. If hw_event->callchain is
set the arch specific perf_callchain() function is called upon to
provide a perf_callchain_entry structure filled with the current
callchain.

If it does so, it is added to the overflow output event.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Paul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090330171024.254266860@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 12 insertions, 1 deletions

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index edf5bfb7ff51..43083afffe0f 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -140,8 +140,9 @@ struct perf_counter_hw_event {
                                 include_tid    :  1, /* include the tid       */
                                 mmap           :  1, /* include mmap data     */
                                 munmap         :  1, /* include munmap data   */
+                                callchain      :  1, /* add callchain data    */
 
-                                __reserved_1   : 52;
+                                __reserved_1   : 51;
 
         __u32                   extra_config_len;
         __u32                   __reserved_4;
@@ -219,6 +220,7 @@ enum perf_event_type {
         PERF_EVENT_OVERFLOW     = 1UL << 31,
         __PERF_EVENT_IP         = 1UL << 30,
         __PERF_EVENT_TID        = 1UL << 29,
+        __PERF_EVENT_CALLCHAIN  = 1UL << 28,
 };
 
 #ifdef __KERNEL__
@@ -504,6 +506,15 @@ extern void perf_counter_mmap(unsigned long addr, unsigned long len,
 extern void perf_counter_munmap(unsigned long addr, unsigned long len,
                                 unsigned long pgoff, struct file *file);
 
+#define MAX_STACK_DEPTH         255
+
+struct perf_callchain_entry {
+        u64     nr;
+        u64     ip[MAX_STACK_DEPTH];
+};
+
+extern struct perf_callchain_entry *perf_callchain(struct pt_regs *regs);
+
 #else
 static inline void
 perf_counter_task_sched_in(struct task_struct *task, int cpu)           { }