linux-kernel - [BUG] perf report: fails to symbolize when vaddr is non zero for shared objects

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Message-ID: <CABPqkBTPruhg+B3N899vEJtAsd8ihDs+oMjOB_C8Xs=ZZE-FDQ@mail.gmail.com>
Date:	Tue, 16 Jun 2015 00:03:01 -0700
From:	Stephane Eranian <eranian@...gle.com>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Jiri Olsa <jolsa@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	David Ahern <dsahern@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"mingo@...e.hu" <mingo@...e.hu>
Subject: [BUG] perf report: fails to symbolize when vaddr is non zero for
 shared objects

Hi,

It has been brought to my attention that on systems where the text
of shared libs is not loaded with a zero virtual address, perf report
fails to symbolize
correctly samples. This is true of older versions of perf and also the latest
in tip.git.

I looked at symbol-elf.c and I did not see a place where the vaddr was taken
into account from the program headers in the case of ET_DYN. I see it for
ET_EXE, though.

$ readelf -e lib.so
  Type:                              DYN (Shared object file)
  ....
  Type          Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
 LOAD           0x000000 0x0000d000 0x0000d000 0x73657c 0x73657c R E 0x1000

If you get samples in the shared lib, they will be off, possibly
attributed to the wrong
functions.

Could this be fixed quickly?
Thanks.
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