linux-kernel - Re: [PATCH 1/1] perf: Fixed perf trace, 32bit return values to 64bit

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Message-ID: <20140929182830.GH3879@kernel.org>
Date:	Mon, 29 Sep 2014 15:28:30 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Chang Hyun Park <heartinpiece@...il.com>
Cc:	linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
	hpa@...or.com
Subject: Re: [PATCH 1/1] perf: Fixed perf trace, 32bit return values to 64bit

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@...fa056691008 //(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
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