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

["rguenth at gcc dot gnu dot org" <sourceware-bugzilla at sourceware dot org>]

------- Additional Comments From rguenth at gcc dot gnu dot org  2010-08-31 14:10 -------
> (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.

Yeah - I've bounced it to our kernel folks.  New started processes work fine,
but a lot of old processes on my system have lost the dirty bits in
/proc/smaps ... let's see what their response will be.


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http://sourceware.org/bugzilla/show_bug.cgi?id=11804

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