Re: 1.5.6-pre: Occasional bad memory accesses within cygwin1.dll

[Christopher Faylor <cgf-no-personal-reply-please at cygwin dot com>]

On Tue, Dec 30, 2003 at 02:36:12PM -0600, Brian Ford wrote:
>On Mon, 29 Dec 2003, Christopher Faylor wrote:
>
>> On Sun, Dec 28, 2003 at 03:52:33PM -0000, Max Bowsher wrote:
>> >I installed a self-built cygwin HEAD version - mostly it works fine, but it
>> >causes odd failures during builds (speculation: race when many processes
>> >being created and destroyed?)
>> >
>> >The most common failure is a Windows error box:
>> >
>> >The instruction at "0x6108621a" references memory at "0x610030b0". The
>> >memory could not be written.
>> >
>> >(These addresses are constant.)
>> >
>> >$ addr2line -e /bin/cygwin1.dll 0x6108621a 0x610030b0
>> >.../src/winsup/cygwin/shm.cc:331
>> >.../src/winsup/cygwin/cygthread.cc:34
>>
>> This isn't too useful, unfortunately.  The line numbers are an artifact
>> of the fact that there is no STABS information in the generated asm in
>> 'sigfe.s'.  Can you get an assembly listing of the lines around this
>> instruction?
>>
>I think this is the same problem.  It shows up all over the place for me
>in the testsuite.
>
>$ env
>GNU gdb 5.3
>Copyright 2002 Free Software Foundation, Inc.
>GDB is free software, covered by the GNU General Public License, and you are
>welcome to change it and/or distribute copies of it under certain conditions.
>Type "show copying" to see the conditions.
>There is absolutely no warranty for GDB.  Type "show warranty" for details.
>This GDB was configured as "i686-pc-cygwin"...
>(gdb) r
>Starting program:
>/home/ford/downloads/cygb2/i686-pc-cygwin/winsup/testsuite/testsuite/checksignal.exe
>
>Program received signal SIGSEGV, Segmentation fault.
>0x6108bcad in _sigfe ()
>Current language:  auto; currently c++
>(gdb) bt
>#0  0x6108bcad in _sigfe ()
>#1  0xffffffff in ?? ()
>#2  0x00402b1f in cygwin_crt0 (f=0x401134 <main>)
>    at ../../../../cygwin/winsup/cygwin/lib/cygwin_crt0.c:24
>#3  0x0040103c in mainCRTStartup ()
>#4  0x77f1bb7b in _system_dlls__ ()
>(gdb) disassemble
>Dump of assembler code for function _sigfe:
>0x6108bc90 <_sigfe>:    push   %edx
>0x6108bc91 <_sigfe+1>:  mov    %fs:0x4,%eax
>0x6108bc97 <_sigfe+7>:  mov    $0x4,%edx
>0x6108bc9c <_sigfe+12>: xadd   %edx,0xffffeff8(%eax)
>0x6108bca3 <_sigfe+19>: lea    0x6108bcb1,%eax
>0x6108bca9 <_sigfe+25>: xchg   %eax,0x8(%esp,1)
>0x6108bcad <_sigfe+29>: mov    %eax,(%edx)
>0x6108bcaf <_sigfe+31>: pop    %edx
>0x6108bcb0 <_sigfe+32>: ret
>End of assembler dump.
>(gdb)

$edx?

cgf

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