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[Bug corefiles/11804] Fix -Wl,-z,relro gcore writer (+maybe reader)
- From: "jan dot kratochvil at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: gdb-prs at sourceware dot org
- Date: 31 Aug 2010 14:06:28 -0000
- Subject: [Bug corefiles/11804] Fix -Wl,-z,relro gcore writer (+maybe reader)
- References: <20100710211433.11804.jan.kratochvil@redhat.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From jan dot kratochvil at redhat dot com 2010-08-31 14:06 -------
(In reply to comment #7)
> And in the core file:
> [67] load NOBITS 00007fac68cc1000 000ed558
> 0000000000001000 0000000000000000 A 0 0 1
Not sure what you have meant but there is NOBITS, therefore it is _not_ present
in the core file.
(In reply to comment #9)
> OTOH a recent 7.1 tree looks much different (but has the same logic and
> also doesn't work for me - but it lost the nice debugging stuff).
Sorry but I am not going to support the former Jeff Johnston's PIE patch magic.
Also there were some post-7.1 PIE fixes, suggesting just to use FSF GDB HEAD as
there will be even still one PIE bug in FSF GDB 7.2.
http://sourceware.org/ml/gdb-patches/2010-07/msg00237.html
(In reply to comment #10)
> Hm. The .dynamic section in memory is different from that in the file-backing
> (at least DT_DEBUG has been filled in by the dynamic loader). But still the
> page is marked clean in /proc/smaps.
I have tested this on Fedora14snapshot + kernel-2.6.33.6-147.fc13.x86_64
and it works for me.
./gdb -nx /usr/libexec/postfix/qmgr
GNU gdb (GDB) 7.2.50.20100831-cvs
[...]
This GDB was configured as "x86_64-unknown-linux-gnu".
[...]
Reading symbols from /usr/libexec/postfix/qmgr...(no debugging symbols
found)...done.
(gdb) start
Temporary breakpoint 1 at 0x8ae0
Starting program: /usr/libexec/postfix/qmgr
[Thread debugging using libthread_db enabled]
Temporary breakpoint 1, 0x00007ffff7fbdae0 in main ()
(gdb) info files
`/usr/libexec/postfix/qmgr', file type elf64-x86-64.
[...]
0x00007ffff81ff940 - 0x00007ffff81ffba0 is .dynamic
7ffff81fe000-7ffff8200000 r--p 00049000 fd:01 6523997
/usr/libexec/postfix/qmgr
Size: 8 kB
Rss: 8 kB
Pss: 8 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 8 kB
Referenced: 8 kB
Swap: 0 kB
KernelPageSize: 4 kB
MMUPageSize: 4 kB
unpatched:
[92] load NOBITS 00007ffff81fe000 115dec 002000 00 A
0 0 1
patched:
[92] load PROGBITS 00007ffff81fe000 002000 00 A 0 0 1
Thanks for the testing, though.
>From your dumps I believe your .dynamic was at 0x7fac68cc1bc0 and its DT_DEBUG
was at 0x7fac68cc1d18 which would suggest there is some problem in Linux
kernel's content of /proc/PID/smaps.
--
http://sourceware.org/bugzilla/show_bug.cgi?id=11804
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