[PATCH v3] perf report: Provide libtraceevent with a kernel symbol resolver

[Wang YanQing]

So that beautifiers wanting to resolve kernel function addresses to
names can do its work, and when we use "perf report" for output of
"perf kmem record", we will get kernel symbol output.

This patch affect the output of "perf report" for the record data
generated by "perf kmem record" looks like below:

Before patch:
0.01%  call_site=ffffffff814e5828 ptr=0x99bb000 bytes_req=3616 bytes_alloc=4096 gfp_flags=GFP_ATOMIC
0.01%  call_site=ffffffff81370b87 ptr=0x428a3060 bytes_req=32 bytes_alloc=32 gfp_flags=GFP_KERNEL|GFP_ZERO

After patch:
0.01%  (aa_alloc_task_context+0x27) call_site=ffffffff81370b87 ptr=0x428a3060 bytes_req=32 bytes_alloc=32 gfp_flags=GFP_KERNEL|GFP_ZERO
0.01%  (__tty_buffer_request_room+0x88) call_site=ffffffff814e5828 ptr=0x99bb000 bytes_req=3616 bytes_alloc=4096 gfp_flags=GFP_ATOMIC

Signed-off-by: Wang YanQing <udknight@xxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
 Changes v2-v3:
 1: Fix one WARNING reported by ./scripts/checkpatch.pl
 Note: the ./scripts/checkpatch.pl report "WARNING: Possible unwrapped commit description"
       for the output of "perf report", I think we can avoid that warning, because the
       original output of "perf report" is unwrapped.

 Changes v1-v2:
 1: Add a before and after output of tools affected by the patch in the changelog.
 2: Rebase the patch to last kernel version.

 tools/perf/builtin-report.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 1eedb18..677ff58 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -1337,6 +1337,15 @@ int cmd_report(int argc, const char **argv)
 		report.range_num = 1;
 	}
 
+	if (session->tevent.pevent &&
+	    pevent_set_function_resolver(session->tevent.pevent,
+					 machine__resolve_kernel_addr,
+					 &session->machines.host) < 0) {
+		pr_err("%s: failed to set libtraceevent function resolver\n",
+		       __func__);
+		return -1;
+	}
+
 	sort__setup_elide(stdout);
 
 	ret = __cmd_report(&report);
-- 
1.8.5.6.2.g3d8a54e.dirty