[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <20160203135551.GA2068@danjae.kornet>
Date: Wed, 3 Feb 2016 22:55:51 +0900
From: Namhyung Kim <namhyung@...nel.org>
To: "Wangnan (F)" <wangnan0@...wei.com>
Cc: acme@...nel.org, adrian.hunter@...el.com, dev@...yps.com,
hekuang@...wei.com, kirr@...edi.com, linux-kernel@...r.kernel.org,
Arnaldo Carvalho de Melo <acme@...hat.com>,
Jiri Olsa <jolsa@...nel.org>,
Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
Li Zefan <lizefan@...wei.com>, pi3orama@....com
Subject: Re: [PATCH 2/2] perf tools: Adjust symbol for shared objects
Hi,
On Wed, Feb 03, 2016 at 10:12:43AM +0800, Wangnan (F) wrote:
>
>
> On 2016/2/2 23:18, Namhyung Kim wrote:
> >On Tue, Feb 02, 2016 at 08:56:06AM +0000, Wang Nan wrote:
> >>He Kuang reported a problem that perf fails to get correct symbol on
> >>Android platform in [1]. The problem can be reproduced on normal x86_64
> >>platform. I will describe the reproducing steps in detail at the end of
> >>commit message.
> >>
> >>The reason of this problem is the missing of symbol adjustment for normal
> >>shared objects. In most of the cases it works correctly, but when
> >>'.text' section have different 'address' and 'offset' the result is
> >>wrong. I checked all shared objects in my working platform, only wine
> >>dll objects and debug objects (in .debug) have this problem. However,
> >>it is common on Android. For example:
> >>
> >> $ readelf -S ./libsurfaceflinger.so | grep \.text
> >> [10] .text PROGBITS 0000000000029030 00012030
> >>
> >>This patch enables symbol adjustment for dynamic objects so the symbol
> >>address got from elfutils would be adjusted correctly.
> >>
> >>Steps to reproduce the problem:
> >>
> >> $ cat << EOF > ./Makefile
> >>PWD := $(shell pwd)
> >>LDFLAGS += "-Wl,-rpath=$(PWD)"
> >>CFLAGS += -g
> >>main: main.c libbuggy.so
> >>libbuggy.so: buggy.c
> >> gcc -g -shared -fPIC -Wl,-Ttext-segment=0x200000 $< -o $@
> >>clean:
> >> rm -rf main libbuggy.so *.o
> >>EOF
> >>
> >> $ cat << EOF > ./buggy.c
> >>int fib(int x)
> >>{
> >> return (x == 0) ? 1 : (x == 1) ? 1 : fib(x - 1) + fib(x - 2);
> >>}
> >>EOF
> >>
> >> $ cat << EOF > ./main.c
> >> #include <stdio.h>
> >>
> >>extern int fix(int x);
> >s/fix/fib/ ?
>
> Thank you. Have you really tested this program?
Nope, but I've been thinking that the symbol resolution code needs to
be updated or fixed.
Thanks,
Namhyung
Powered by blists - more mailing lists