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From: Wang Nan <wangnan0@huawei.com>
To: Jiri Olsa <jolsa@redhat.com>, <acme@kernel.org>,
	<jolsa@kernel.org>, <mingo@redhat.com>
Cc: <namhyung@kernel.org>, <lizefan@huawei.com>, <pi3orama@163.com>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/4] perf tools: unwind: ensure unwind hooks return negative errorno.
Date: Tue, 7 Apr 2015 16:30:08 +0800	[thread overview]
Message-ID: <55239590.2020109@huawei.com> (raw)
In-Reply-To: <551BE78A.6070800@huawei.com>

Hi folks,

I'm rethinking --map-adjustment now, and I believe what we need should be something
like 'perf inject', which allows us to inject fake mmap events into perf.data to
make 'perf report' believe some //anon memory are file based mapping. Patch 2/4 - 4/4
seem not useful now. However, patch 1/4 is still useful because it is a bugfix. Could
you please drop the other 3 patches and merge this one?

Thank you.

On 2015/4/1 20:41, Wang Nan wrote:
> On 2015/4/1 20:12, Jiri Olsa wrote:
>> On Wed, Apr 01, 2015 at 10:33:12AM +0000, Wang Nan wrote:
>>> According to man pages of libunwind, unwind hooks should return
>>> 'negative value of one of the unw_error_t error-codes', they are
>>> different from generic error code. In addition, access_dso_mem()
>>> returns '!(size == sizeof(*data))', compiler never ensure it is
>>> negative when failure, which causes libunwind get undesire value
>>> when accessing //anon memory.
>>>
>>> This patch fixes this problem by force returning negative value when
>>> error, instead of returning 'ret' itself when it is non-zero.
>>
>> hum, how about find_proc_info callback.. should it follow the same rules?
>>
> 
> Yes, but it only returns -EINVAL and dwarf_search_unwind_table(....). The latter
> one is part of libunwind so we can trust it returns negative when fail.
> 
>> thanks,
>> jirka
>>
> 
> 
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  reply	other threads:[~2015-04-07  8:31 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-01 10:33 [PATCH 0/4] perf tools: introduce --map-adjustment Wang Nan
2015-04-01 10:33 ` [PATCH 1/4] perf tools: unwind: ensure unwind hooks return negative errorno Wang Nan
2015-04-01 12:12   ` Jiri Olsa
2015-04-01 12:41     ` Wang Nan
2015-04-07  8:30       ` Wang Nan [this message]
2015-04-01 10:33 ` [PATCH 2/4] perf tools: introduce machine_map_new to merge mmap/mmap2 processing code Wang Nan
2015-04-01 12:18   ` Jiri Olsa
2015-04-01 14:58     ` Arnaldo Carvalho de Melo
2015-04-01 10:33 ` [PATCH 3/4] perf tools: report: introduce --map-adjustment argument Wang Nan
2015-04-01 13:21   ` Jiri Olsa
2015-04-02  1:15     ` Wang Nan
2015-04-01 14:23   ` pi3orama
2015-04-01 10:33 ` [PATCH 4/4] perf tools: unwinding: try to read from map_adj for a unmapped address Wang Nan

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