perf_counter: Make callchain samples extensible

Before exposing upstream tools to a callchain-samples ABI, tidy it
up to make it more extensible in the future:

Use markers in the IP chain to denote context, use (u64)-1..-4095 range
for these context markers because we use them for ERR_PTR(), so these
addresses are unlikely to be mapped.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 17 insertions, 11 deletions

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 0765e8e69843..e7e7e0242767 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -343,23 +343,22 @@ enum perf_event_type {
          *      { u64                   nr;
          *        { u64 id, val; }      cnt[nr];  } && PERF_SAMPLE_GROUP
          *
-         *      { u16                   nr,
-         *                              hv,
-         *                              kernel,
-         *                              user;
+         *      { u64                   nr,
          *        u64                   ips[nr];  } && PERF_SAMPLE_CALLCHAIN
          * };
          */
 };
 
-#define MAX_STACK_DEPTH                 255
+enum perf_callchain_context {
+        PERF_CONTEXT_HV                 = (__u64)-32,
+        PERF_CONTEXT_KERNEL             = (__u64)-128,
+        PERF_CONTEXT_USER               = (__u64)-512,
 
-struct perf_callchain_entry {
-        __u16                           nr;
-        __u16                           hv;
-        __u16                           kernel;
-        __u16                           user;
-        __u64                           ip[MAX_STACK_DEPTH];
+        PERF_CONTEXT_GUEST              = (__u64)-2048,
+        PERF_CONTEXT_GUEST_KERNEL       = (__u64)-2176,
+        PERF_CONTEXT_GUEST_USER         = (__u64)-2560,
+
+        PERF_CONTEXT_MAX                = (__u64)-4095,
 };
 
 #ifdef __KERNEL__
@@ -381,6 +380,13 @@ struct perf_callchain_entry {
 #include <linux/pid_namespace.h>
 #include <asm/atomic.h>
 
+#define PERF_MAX_STACK_DEPTH            255
+
+struct perf_callchain_entry {
+        __u64                           nr;
+        __u64                           ip[PERF_MAX_STACK_DEPTH];
+};
+
 struct task_struct;
 
 /**