From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Chang Hyun Park <heartinpiece@gmail.com>
Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de,
mingo@redhat.com, hpa@zytor.com
Subject: Re: [PATCH 1/1] perf: Fixed perf trace, 32bit return values to 64bit
Date: Mon, 29 Sep 2014 15:28:30 -0300 [thread overview]
Message-ID: <20140929182830.GH3879@kernel.org> (raw)
In-Reply-To: <1411736041-8017-1-git-send-email-heartinpiece@gmail.com>
Em Fri, Sep 26, 2014 at 09:54:01PM +0900, Chang Hyun Park escreveu:
> perf trace for syscalls resulted in mmap return values being stripped of
> the top 32 bits, and actually printing only the lower 32 bits. This was
> because the ret value was of an 'int' type and not a 'long' type.
>
> The Problem:
> 991258501.244 ( 0.004 ms): mmap(len: 40001536, prot: READ|WRITE, flags:
> PRIVATE|ANONYMOUS, fd: -1) = 0x56691000
> 991258501.257 ( 0.000 ms): minfault [_int_malloc+0x1038] =>
> //anon@0x7fa056691008 //(d.)
>
> The first line shows an mmap, which succeeds and returns 0x56691000.
> However the next line shows a memory access to that virtual memory area,
> specifically to 0x7fa056691008. The upper 32 bit is lost due to the
> problem mentioned above, and thus mmap's return value didn't have the
> upper 0x7fa0.
Thanks, applied to my perf/core branch.
- Arnaldo
next prev parent reply other threads:[~2014-09-29 18:28 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-26 12:54 [PATCH 1/1] perf: Fixed perf trace, 32bit return values to 64bit Chang Hyun Park
2014-09-29 18:28 ` Arnaldo Carvalho de Melo [this message]
2014-10-03 5:25 ` [tip:perf/core] perf trace: Fix mmap return address truncation to 32-bit tip-bot for Chang Hyun Park
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