[Bug corefiles/11804] Fix -Wl,-z,relro gcore writer (+maybe reader)

["jan dot kratochvil at redhat dot com" <sourceware-bugzilla@sourceware.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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