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From: Pedro Alves <palves@redhat.com>
To: Markus Metzger <markus.t.metzger@intel.com>
Cc: gdb-patches@sourceware.org
Subject: Re: [PATCH v3 3/3] btrace, vdso: add vdso target sections
Date: Thu, 29 May 2014 17:03:00 -0000	[thread overview]
Message-ID: <53876874.3080503@redhat.com> (raw)
In-Reply-To: <5387663A.5040704@redhat.com>

On 05/29/2014 05:54 PM, Pedro Alves wrote:
> Hi Markus,
> 
> On 05/21/2014 08:01 AM, Markus Metzger wrote:
>> When loading symbols for the vdso, also add its sections to target_sections.
>>
>> This fixes an issue with record btrace where vdso instructions could not be
>> disassembled during replay.
>>
>> 2014-05-21  Markus Metzger  <markus.t.metzger@intel.com>
>>
>> 	* symfile-mem.c (symbol_file_add_from_memory): Add BFD sections.
> 
> Unfortunately this caused regressions in break-interp.exp:
> 
>  Running ../../../src/gdb/testsuite/gdb.base/break-interp.exp ...
>  ERROR: Process no longer exists
> 
> That is GDB crashing.
> 
> 589fdceb99db9868e34bc976b7e234dbfaf327e2 is the first bad commit
> commit 589fdceb99db9868e34bc976b7e234dbfaf327e2
> Author: Markus Metzger <markus.t.metzger@intel.com>
> Date:   Wed Apr 2 09:54:11 2014 +0200
> 
>     btrace, vdso: add vdso target sections
> 
>     When loading symbols for the vdso, also add its sections to target_sections.
> 
>     This fixes an issue with record btrace where vdso instructions could not be
>     disassembled during replay.
> 
>         * symfile-mem.c (symbol_file_add_from_memory): Add BFD sections.
> 
>     testsuite/
>         * gdb.btrace/vdso.c: New.
>         * gdb.btrace/vdso.exp: New.
> 
> 
> Core was generated by `/home/pedro/gdb/mygit/build/gdb/testsuite/../../gdb/gdb -nw -nx -data-directory'.
> Program terminated with signal SIGSEGV, Segmentation fault.
> #0  0x0000000000647bce in exec_set_section_address (filename=0x27bb1f0 "/home/pedro/gdb/mygit/build/gdb/testsuite/gdb.base/break-interp-LDprelinkNOdebugNO", index=0,
>     address=139930618982856) at ../../src/gdb/exec.c:919
> 919           if (filename_cmp (filename, p->the_bfd_section->owner->filename) == 0

'p', a target section, points at garbage.

Hmm, wait, nothing is removing the vdso symbols target sections, like ever,
not even when the process dies, isn't it?  I guess that's it.

-- 
Pedro Alves


  reply	other threads:[~2014-05-29 17:03 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-05-21  7:01 [PATCH v3 1/3] btrace: control memory access during replay Markus Metzger
2014-05-21  7:01 ` [PATCH v3 3/3] btrace, vdso: add vdso target sections Markus Metzger
2014-05-21  9:55   ` Pedro Alves
2014-05-29 16:54   ` Pedro Alves
2014-05-29 17:03     ` Pedro Alves [this message]
2014-06-02  8:20       ` Metzger, Markus T
2014-06-02  9:43         ` Metzger, Markus T
2014-06-02 12:41       ` Metzger, Markus T
2014-06-04 12:37         ` Metzger, Markus T
2014-05-21  7:02 ` [PATCH v3 2/3] test, gcore: move capture_command_output into lib/gdb.exp Markus Metzger
2014-05-21  9:55   ` Pedro Alves
2014-05-21  9:55 ` [PATCH v3 1/3] btrace: control memory access during replay Pedro Alves

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