From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
Ingo Molnar <mingo@kernel.org>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
David Ahern <dsahern@gmail.com>,
lkml <linux-kernel@vger.kernel.org>,
"Steven Rostedt (Red Hat)" <rostedt@goodmis.org>,
Oleg Nesterov <oleg@redhat.com>,
"David A. Long" <dave.long@linaro.org>,
systemtap@sourceware.org, yrl.pp-manager.tt@hitachi.com
Subject: Re: [PATCH -tip 3/3] perf-probe: Use the actual address as a hint for uprobes
Date: Mon, 23 Dec 2013 10:50:00 -0000 [thread overview]
Message-ID: <52B81562.5000607@hitachi.com> (raw)
In-Reply-To: <87wqiwc8ly.fsf@sejong.aot.lge.com>
(2013/12/23 16:46), Namhyung Kim wrote:
> On Mon, 23 Dec 2013 06:54:38 +0900, Masami Hiramatsu wrote:
>> (2013/12/21 3:03), Arnaldo Carvalho de Melo wrote:
>>> Em Fri, Dec 20, 2013 at 10:03:02AM +0000, Masami Hiramatsu escreveu:
>> BTW, I'm not sure why debuginfo and nm shows symbol address + 0x400000,
>> and why the perf's map/symbol can remove this offset. Could you tell me
>> how it works?
>> If I can get the offset (0x400000) from binary, I don't need this kind
>> of ugly hacks...
>
> AFAIK the actual symbol address is what nm (and debuginfo) shows. But
> perf adjusts symbol address to have a relative address from the start of
> mapping (i.e. file offset) like below:
>
> sym.st_value -= shdr.sh_addr - shdr.sh_offset;
Thanks! this is what I really need!
> This way, we can handle mmap and symbol address almost uniformly
> (i.e. ip = map->start + symbol->address). But this requires the mmap
> event during perf record. For perf probe, we might need to synthesize
> mapping info from the section/segment header since it doesn't have the
> mmap event. Currently, the dso__new_map() just creates a map starts
> from 0.
I think the uprobe requires only the relative address, doesn't that?
Thank you,
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com
next prev parent reply other threads:[~2013-12-23 10:50 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-20 10:08 [PATCH -tip 0/3] perf-probe: Dwarf support " Masami Hiramatsu
2013-12-20 10:08 ` [PATCH -tip 2/3] perf-probe: Support dwarf on uprobe events Masami Hiramatsu
2013-12-20 18:02 ` Arnaldo Carvalho de Melo
2013-12-22 21:39 ` Masami Hiramatsu
2013-12-23 14:34 ` Arnaldo Carvalho de Melo
2013-12-24 1:03 ` Masami Hiramatsu
2013-12-20 10:08 ` [PATCH -tip 3/3] perf-probe: Use the actual address as a hint for uprobes Masami Hiramatsu
2013-12-20 18:04 ` Arnaldo Carvalho de Melo
2013-12-22 21:54 ` Masami Hiramatsu
2013-12-23 7:46 ` Namhyung Kim
2013-12-23 10:50 ` Masami Hiramatsu [this message]
2013-12-24 7:54 ` Namhyung Kim
2013-12-24 8:28 ` Masami Hiramatsu
2013-12-24 8:46 ` Namhyung Kim
2013-12-24 15:03 ` Masami Hiramatsu
2013-12-20 10:08 ` [PATCH -tip 1/3] [CLEANUP] perf-probe: Expand given path to absolute path Masami Hiramatsu
2013-12-20 18:00 ` Arnaldo Carvalho de Melo
2013-12-22 21:35 ` Masami Hiramatsu
2013-12-23 14:28 ` Arnaldo Carvalho de Melo
2013-12-24 6:51 ` Masami Hiramatsu
2013-12-23 6:17 ` Namhyung Kim
2013-12-23 10:46 ` Masami Hiramatsu
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