From: He Kuang <hekuang@huawei.com>
To: <peterz@infradead.org>, "mingo@redhat.com" <mingo@redhat.com>,
"Arnaldo Carvalho de Melo" <acme@kernel.org>,
Jiri Olsa <jolsa@redhat.com>, <rabin.vincent@axis.com>,
<namhyung@kernel.org>, Wang Nan <wangnan0@huawei.com>
Cc: <linux-kernel@vger.kernel.org>
Subject: [bug] wrong result of android callchain
Date: Tue, 5 Jan 2016 17:14:37 +0800 [thread overview]
Message-ID: <568B897D.1000209@huawei.com> (raw)
I found a wrong result of aarch64 callchain when using perf script on
a android phone.
Here's the callchain record fragment from the output of perf script:
init 369 [002] 339.970607: raw_syscalls:sys_enter: NR 22 (b, 7fd9e360a0, 10, ffffffff, 0, 8)
...
230ac [unknown] (/system/lib64/libsurfaceflinger.so)
11a0 main (/system/bin/surfaceflinger)
1c3fc __libc_init (/system/lib64/libc.so)
fd0 _start (/system/bin/surfaceflinger)
29ec __dl__start (/system/bin/linker64)
The fault occured in the '[unknown]' line, from objdump result of
/system/bin/surfaceflinger, we can see the branch instruction before
0x11a0:
# objdump /system/bin/surfaceflinger
1198: f9400fe0 ldr x0, [sp,#24]
119c: 97ffff05 bl db0 <_ZN7android14SurfaceFlinger3runEv@plt>
11a0: f9400be8 ldr x8, [sp,#16]
11a4: b40000c8 cbz x8, 11bc <main+0x150>
The function '_ZN7android14SurfaceFlinger3runEv' is located at 0x3a094
~ 0x3a0ac in libsurfaceflinger.so, but perf misparsed that value to
0x230ac:
# objdump libsurfaceflinger.so
000000000003a094 <_ZN7android14SurfaceFlinger3runEv>:
3a094: a9be4ff4 stp x20, x19, [sp,#-32]!
3a098: a9017bfd stp x29, x30, [sp,#16]
3a09c: 910043fd add x29, sp, #0x10
3a0a0: 910c0013 add x19, x0, #0x300
3a0a4: aa1303e0 mov x0, x19
3a0a8: 97fff12f bl 36564 <_ZN7android12MessageQueue11waitMessageEv>
3a0ac: 17fffffe b 3a0a4 <_ZN7android14SurfaceFlinger3runEv+0x10>
There's a difference of 0x17000 between those two offsets, it seems
that this value is the VirtAddr of this dynamic library.
# readelf -a libsurfaceflinger.so
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000000000 0x0000000000017000 0x0000000000017000
0x0000000000057258 0x0000000000057258 R E 1000
next reply other threads:[~2016-01-05 9:16 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-05 9:14 He Kuang [this message]
2016-01-05 10:20 ` [bug] wrong result of android callchain Peter Zijlstra
2016-01-05 11:13 ` Will Deacon
2016-01-06 8:26 ` [PATCH] perf symbols: Fix wrong symbol offset according to p_addr He Kuang
2016-01-11 11:25 ` Ingo Molnar
2016-01-12 2:58 ` [PATCH v2] " He Kuang
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