From: He Kuang <hekuang@huawei.com>
To: <a.p.zijlstra@chello.nl>, <mingo@redhat.com>, <acme@kernel.org>,
<masami.hiramatsu.pt@hitachi.com>, <namhyung@kernel.org>
Cc: <wangnan0@huawei.com>, <linux-kernel@vger.kernel.org>
Subject: [PATCH] perf probe: Fix failure to probe events on arm
Date: Mon, 15 Jun 2015 08:06:53 +0000 [thread overview]
Message-ID: <1434355613-110216-1-git-send-email-hekuang@huawei.com> (raw)
Fix failure to probe events on arm, problem is introduced by commit
5a51fcd1f30c ("perf probe: Skip kernel symbols which is out of
.text"). For some architectures, label '_etext' is not in the .text
section(in .notes section for arm/arm64). Label out of .text section is
not loaded as symbols and we got a zero value when look up its address,
which causes all events be wrongly skiped.
This patch uses kernel map->end when failed to get the address of
'_etext' and fixes the problem.
Problem can be reproduced on arm as following:
# perf probe --add='generic_perform_write'
generic_perform_write+0 is out of .text, skip it.
Probe point 'generic_perform_write' not found.
Error: Failed to add events. Reason: No such file or directory (Code: -2)
After this patch:
# perf probe --add='generic_perform_write'
Added new event:
probe:generic_perform_write (on generic_perform_write)
You can now use it in all perf tools, such as:
perf record -e probe:generic_perform_write -aR sleep 1
Signed-off-by: He Kuang <hekuang@huawei.com>
---
tools/perf/util/probe-event.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index daa24a2..ee26961 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -575,8 +575,22 @@ static int post_process_probe_trace_events(struct probe_trace_event *tevs,
pr_warning("Relocated base symbol is not found!\n");
return -EINVAL;
}
- /* Get the address of _etext for checking non-probable text symbol */
+ /* Get the address of _etext for checking non-probable text symbol,
+ for some architectures (e.g. arm, arm64), _etext is out of .text
+ section and not loaded as symbols, use kernel map->end instead.
+ */
etext_addr = kernel_get_symbol_address_by_name("_etext", false);
+ if (etext_addr == 0) {
+ struct map *map;
+
+ map = kernel_get_module_map(NULL);
+ if (!map) {
+ pr_err("Failed to get a map for kernel\n");
+ return -EINVAL;
+ }
+
+ etext_addr = map->end;
+ }
for (i = 0; i < ntevs; i++) {
if (tevs[i].point.address && !tevs[i].point.retprobe) {
--
1.8.5.2
next reply other threads:[~2015-06-15 8:07 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-15 8:06 He Kuang [this message]
2015-06-15 14:49 ` [PATCH] perf probe: Fix failure to probe events on arm Arnaldo Carvalho de Melo
2015-06-16 6:05 ` Masami Hiramatsu
2015-06-16 13:39 ` Arnaldo Carvalho de Melo
2015-06-16 15:26 ` hekuang
2015-06-17 8:52 ` Masami Hiramatsu
2015-06-17 9:43 ` He Kuang
2015-06-17 11:18 ` Masami Hiramatsu
2015-06-18 2:49 ` [PATCH v2] " He Kuang
2015-06-19 21:08 ` Arnaldo Carvalho de Melo
2015-06-23 3:07 ` Masami Hiramatsu
2015-06-23 3:07 ` Masami Hiramatsu
2015-06-25 7:57 ` [tip:perf/core] " tip-bot for He Kuang
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