Subject: gdb: single stepping fails with unrelated "Cannot access memory at address 0x7c8" Package: gdb Version: 6.8-3 Severity: important
*** Please type your report below this line *** After a single stepping a few times (using a command macro "g" that expands to "stepi\n x/i $pc\n") then single stepping and many other commands fail to work at all. The complaint is "Cannot access memory at address 0x7c8" where address 0x7c8 is not relevant to any part of the requested action. This makes gdb mostly unusable. The architecture is armel-eabi on a Linksys NSLU2 (armv5te). Here is a copy+paste from text console: ----- $ gdb date.upx GNU gdb 6.8-debian Copyright (C) 2008 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "arm-linux-gnueabi"... (no debugging symbols found) (gdb) b *0xd9f0 Breakpoint 1 at 0xd9f0 (gdb) run Starting program: /home/jreiser/date.upx Breakpoint 1, 0x0000d9f0 in ?? () (gdb) x/i $pc Cannot access memory at address 0x0 0xd9f0: ldm r12, {r1, r2, r10, r11} (gdb) g Cannot access memory at address 0x264 0x0000d9f4 in ?? () 0xd9f4: add r10, r10, r12 (gdb) Cannot access memory at address 0x264 0x0000d9f8 in ?? () 0xd9f8: add r11, r11, r12 (gdb) Cannot access memory at address 0x7c8 (gdb) info reg r0 0x0 0x0 r1 0x59dc 0x59dc r2 0x20000 0x20000 r3 0x0 0x0 r4 0x0 0x0 r5 0x0 0x0 r6 0x0 0x0 r7 0x0 0x0 r8 0x0 0x0 r9 0x0 0x0 r10 0xdb6c 0xdb6c r11 0xdc40 0xdc40 r12 0xd9dc 0xd9dc sp 0xbeda3970 0xbeda3970 lr 0x0 0x0 pc 0xd9fc 0xd9fc fps 0x1001000 0x1001000 cpsr 0x10 0x10 (gdb) x/i $pc Cannot access memory at address 0x7c8 (gdb) p $pc Cannot access memory at address 0x7c8 (gdb) x/i 0xd9fc 0xd9fc: mov r0, r2 (gdb) g Cannot access memory at address 0x7c8 (gdb) x/i 0xd9fc 0xd9fc: mov r0, r2 (gdb) 0xda00: sub r9, r12, r1 (gdb) 0xda04: add r1, r1, #4096 ; 0x1000 (gdb) tbreak *$_ Breakpoint 2 at 0xda04 (gdb) c Continuing. 0x0000da04 in ?? () (gdb) x/i $pc Cannot access memory at address 0x7c8 (gdb) g Cannot access memory at address 0x7c8 (gdb) q The program is running. Exit anyway? (y or n) y $ ----- I will try to attach the complete program date.upx: -rwxr-xr-x 1 jreiser jreiser 25148 Jul 20 13:45 date.upx The relevant contents of $HOME/.gdbinit are: ----- set output-radix 0x10 define g stepi x/i $pc end ----- -- System Information: Debian Release: lenny/sid APT prefers unstable APT policy: (500, 'unstable'), (500, 'testing') Architecture: armel (armv5tel) Kernel: Linux 2.6.24-1-ixp4xx Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968) Shell: /bin/sh linked to /bin/bash Versions of packages gdb depends on: ii libc6 2.7-10 GNU C Library: Shared libraries ii libexpat1 1.95.8-4 XML parsing C library - runtime li ii libgcc1 1:4.3.1-2 GCC support library ii libncurses5 5.6+20080308-1 Shared libraries for terminal hand ii libreadline5 5.2-3 GNU readline and history libraries gdb recommends no packages. -- no debconf information --
date.upx
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