perf probe: Support static and global variables

Add static and global variables support to perf probe.
This allows user to trace non-local variables (and
structure members) at probe points.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100519195749.2885.17451.stgit@localhost6.localdomain6>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 12 insertions, 3 deletions

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 351baa9a3695..09cf5465e10a 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -926,6 +926,7 @@ out:
 static int synthesize_kprobe_trace_arg(struct kprobe_trace_arg *arg,
                                        char *buf, size_t buflen)
 {
+        struct kprobe_trace_arg_ref *ref = arg->ref;
         int ret, depth = 0;
         char *tmp = buf;
 
@@ -939,16 +940,24 @@ static int synthesize_kprobe_trace_arg(struct kprobe_trace_arg *arg,
         buf += ret;
         buflen -= ret;
 
+        /* Special case: @XXX */
+        if (arg->value[0] == '@' && arg->ref)
+                        ref = ref->next;
+
         /* Dereferencing arguments */
-        if (arg->ref) {
-                depth = __synthesize_kprobe_trace_arg_ref(arg->ref, &buf,
+        if (ref) {
+                depth = __synthesize_kprobe_trace_arg_ref(ref, &buf,
                                                           &buflen, 1);
                 if (depth < 0)
                         return depth;
         }
 
         /* Print argument value */
-        ret = e_snprintf(buf, buflen, "%s", arg->value);
+        if (arg->value[0] == '@' && arg->ref)
+                ret = e_snprintf(buf, buflen, "%s%+ld", arg->value,
+                                 arg->ref->offset);
+        else
+                ret = e_snprintf(buf, buflen, "%s", arg->value);
         if (ret < 0)
                 return ret;
         buf += ret;