2 files changed, 39 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)           { }
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index d93e9ddf7848..860cdc26bd7a 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1654,6 +1654,17 @@ void perf_counter_do_pending(void)
 }
 
 /*
+ * Callchain support -- arch specific
+ */
+
+struct perf_callchain_entry *
+__attribute__((weak))
+perf_callchain(struct pt_regs *regs)
+{
+        return NULL;
+}
+
+/*
  * Output
  */
 
@@ -1764,6 +1775,8 @@ static void perf_output_simple(struct perf_counter *counter,
         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 @@ static void perf_output_simple(struct perf_counter *counter,
                 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 @@ static void perf_output_simple(struct perf_counter *counter,
         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);
 }