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>
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index d93e9dd..860cdc2 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1654,6 +1654,17 @@
}
/*
+ * Callchain support -- arch specific
+ */
+
+struct perf_callchain_entry *
+__attribute__((weak))
+perf_callchain(struct pt_regs *regs)
+{
+ return NULL;
+}
+
+/*
* Output
*/
@@ -1764,6 +1775,8 @@
struct {
u32 pid, tid;
} tid_entry;
+ struct perf_callchain_entry *callchain = NULL;
+ int callchain_size = 0;
header.type = PERF_EVENT_OVERFLOW;
header.size = sizeof(header);
@@ -1781,6 +1794,17 @@
header.size += sizeof(tid_entry);
}
+ if (counter->hw_event.callchain) {
+ callchain = perf_callchain(regs);
+
+ if (callchain) {
+ callchain_size = (1 + callchain->nr) * sizeof(u64);
+
+ header.type |= __PERF_EVENT_CALLCHAIN;
+ header.size += callchain_size;
+ }
+ }
+
ret = perf_output_begin(&handle, counter, header.size, nmi);
if (ret)
return;
@@ -1791,6 +1815,9 @@
if (counter->hw_event.include_tid)
perf_output_put(&handle, tid_entry);
+ if (callchain)
+ perf_output_copy(&handle, callchain, callchain_size);
+
perf_output_end(&handle);
}