From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: He Kuang <hekuang@huawei.com>,
a.p.zijlstra@chello.nl, mingo@redhat.com, acme@kernel.org,
namhyung@kernel.org
Cc: wangnan0@huawei.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] perf probe: Fix failure to probe events on arm
Date: Tue, 23 Jun 2015 12:07:33 +0900 [thread overview]
Message-ID: <5588CD75.7080701@hitachi.com> (raw)
In-Reply-To: <1434595750-129791-1-git-send-email-hekuang@huawei.com>
On 2015/06/18 11:49, He Kuang wrote:
> 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 skip checking text address range 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.
>
> 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
Looks good to me :)
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Thanks!
>
> Signed-off-by: He Kuang <hekuang@huawei.com>
> ---
> tools/perf/util/probe-event.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 076527b..381f23a 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -249,8 +249,12 @@ static void clear_probe_trace_events(struct probe_trace_event *tevs, int ntevs)
> static bool kprobe_blacklist__listed(unsigned long address);
> static bool kprobe_warn_out_range(const char *symbol, unsigned long address)
> {
> + u64 etext_addr;
> +
> /* Get the address of _etext for checking non-probable text symbol */
> - if (kernel_get_symbol_address_by_name("_etext", false) < address)
> + etext_addr = kernel_get_symbol_address_by_name("_etext", false);
> +
> + if (etext_addr != 0 && etext_addr < address)
> pr_warning("%s is out of .text, skip it.\n", symbol);
> else if (kprobe_blacklist__listed(address))
> pr_warning("%s is blacklisted function, skip it.\n", symbol);
>
--
Masami HIRAMATSU
Linux Technology Research Center, System Productivity Research Dept.
Center for Technology Innovation - Systems Engineering
Hitachi, Ltd., Research & Development Group
E-mail: masami.hiramatsu.pt@hitachi.com
--
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next prev parent reply other threads:[~2015-06-23 3:07 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-15 8:06 [PATCH] perf probe: Fix failure to probe events on arm He Kuang
2015-06-15 14:49 ` 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 [this message]
2015-06-25 7:57 ` [tip:perf/core] " tip-bot for He Kuang
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