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Subject[tip:perf/core] perf probe: Fix to get ummapped symbol address on kernel
Commit-ID:  e6d7c91c8c5ea532584056f3e8bf1643310c8ef7
Gitweb: http://git.kernel.org/tip/e6d7c91c8c5ea532584056f3e8bf1643310c8ef7
Author: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
AuthorDate: Sun, 22 Mar 2015 20:40:22 +0900
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 24 Mar 2015 12:07:04 -0300

perf probe: Fix to get ummapped symbol address on kernel

Fix to get correctly unmapped symbol address on kernel. This allows us
to probe on syscall symbols which are aliases of SyS_ functions with
using debuginfo.

Without this fix:
----
# ./perf probe -a sys_write
Failed to find debug information for address 3b0100
Probe point 'sys_write' not found.
Error: Failed to add events.
----
The address 0x3b0100 is a mapped address, and not usable
in debuginfo.

With this fix:
----
# ./perf probe -a sys_write
Added new event:
probe:sys_write (on sys_write)

You can now use it in all perf tools, such as:

perf record -e probe:sys_write -aR sleep 1
----

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20150322114022.32639.19096.stgit@localhost.localdomain
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/probe-event.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 6b95985..8feac07 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -310,7 +310,10 @@ static int find_alternative_probe_point(struct debuginfo *dinfo,

/* Find the address of given function */
map__for_each_symbol_by_name(map, pp->function, sym) {
- address = sym->start;
+ if (uprobes)
+ address = sym->start;
+ else
+ address = map->unmap_ip(map, sym->start);
break;
}
if (!address) {

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