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Date: Wed, 03 Jul 2013 08:34:00 -0000
Message-ID: <CAKhyrx_TULNrWwSJ0zPq4tgd8MOpkhSRYZfbMRFcRLw7P0mj4Q@mail.gmail.com>
Subject: re: vdso
From: vijay nag <vijunag@gmail.com>
To: gdb@sourceware.org
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X-SW-Source: 2013-07/txt/msg00009.txt.bz2

Hello,

I recently upgraded my compiler/glibc to gcc-4.7.2/glibc-2.17. If I
enable vdso, gdb is unable to crawl through the stack(back-trace) when
the program does a jump to vdso-area to execute
sysenter system call.

Is it a known issue ?

(gdb) bt
#0  0xb7fff410 in ?? ()
#1  0x122f234e in main (argc=3D4, argv=3D0xbffff854, env=3D0xbffff86c) at
main/sn_main.c:450
(gdb) info register
eax            0xfffffffc	-4
ecx            0x19	25
edx            0x6	6
ebx            0x1dc24c48	499272776
esp            0xbffff2b8	0xbffff2b8
ebp            0xbffff768	0xbffff768
esi            0x6	6
edi            0x43	67
eip            0xb7fff410	0xb7fff410
eflags         0x246	[ PF ZF IF ]
cs             0x73	115
ss             0x7b	123
ds             0x7b	123
es             0x7b	123
fs             0x0	0
gs             0x33	51
(gdb)  disassemble $eip

0xb7fff400      push   %ecx

                              =E2=94=82
   =E2=94=820xb7fff401      push   %edx

                                  =E2=94=82
   =E2=94=820xb7fff402      push   %ebp

                                  =E2=94=82
   =E2=94=820xb7fff403      mov    %esp,%ebp

                                  =E2=94=82
   =E2=94=820xb7fff405      sysenter

                                  =E2=94=82
   =E2=94=820xb7fff407      nop

                                  =E2=94=82
   =E2=94=820xb7fff408      nop

                                  =E2=94=82
   =E2=94=820xb7fff409      nop

                                  =E2=94=82
   =E2=94=820xb7fff40a      nop

                                  =E2=94=82
   =E2=94=820xb7fff40b      nop

                                  =E2=94=82
   =E2=94=820xb7fff40c      nop

                                  =E2=94=82
   =E2=94=820xb7fff40d      nop

                                  =E2=94=82
   =E2=94=820xb7fff40e      jmp    0xb7fff403

                                  =E2=94=82
   =E2=94=820xb7fff410      pop    %ebp

                                  =E2=94=82
   =E2=94=820xb7fff411      pop    %edx

                                  =E2=94=82
   =E2=94=820xb7fff412      pop    %ecx

                                  =E2=94=82
   =E2=94=820xb7fff413      ret

cat /proc/15896/smaps | grep vdso
778:b7fff000-b8000000 r-xp b7fff000 00:00 0          [vdso]

Does vdso come with symbols ?