From: Petr Hracek <phracek@redhat.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: 20614@debbugs.gnu.org
Subject: bug#20614: Segmentation fault when building on Power8 Little Endian
Date: Mon, 5 Oct 2015 11:16:32 +0200 [thread overview]
Message-ID: <56123FF0.3040104@redhat.com> (raw)
In-Reply-To: <83twq5zpne.fsf@gnu.org>
On 10/05/2015 10:27 AM, Eli Zaretskii wrote:
>> Cc: 20614@debbugs.gnu.org
>> From: Petr Hracek <phracek@redhat.com>
>> Date: Mon, 5 Oct 2015 09:40:15 +0200
>>
>>>>>> What does this GDB command display in frame #1:
>>>>>>
>>>>>> (gdb) p old_section_names + NEW_SECTION_H (nn).sh_name
>>>>>>
>>>>>> ?
>>>>>>
>>>>>> It is a really strange.
>>>>>> in our unexelf.c is NEW_SECTION_H defined as
>>>>>>
>>>>>> #define NEW_SECTION_H(n) \
>>>>>> (*(ElfW (Shdr) *) ((byte *) new_section_h + new_file_h->e_shentsize * (n)))
>>>>>>
>>>>>> Paul Eggert did a some patch 1 or 2 year ago and modify it to
>>>>>> #define NEW_SECTION_H(n) \
>>>>>> (*(ElfW (Shdr) *) entry_address (new_section_h, n, new_file_h->e_shentsize))
>>>>>>
>>>>>> (gdb) frame 1
>>>>>> #1 0x00000000102e3724 in unexec (new_name=0x116387e8
>>>>>> "/home/phracek/rpmbuild/BUILD/emacs-24.3/src/emacs", old_name=0x11638838
>>>>>> "/home/phracek/rpmbuild/BUILD/emacs-24.3/src/temacs")
>>>>>> at unexelf.c:1258
>>>>>> 1258 if (!strcmp (old_section_names + NEW_SECTION_H (nn).sh_name, ".data")
>>>>>> (gdb) p old_section_names
>>>>>> $1 = 0x3fffab1dbfcc ""
>>>>>> (gdb) p old_section_names + NEW_SECTION_H (nn).sh_name
>>>>>> No symbol "NEW_SECTION_H" in current context.
>>>>> Use the expansion of that macro instead to display the value.
>>>> How to use the expansion.
>>> Just type it by hand:
>>>
>>> (gdb) p old_section_names + (*(ElfW (Shdr) *) ((byte *) new_section_h + new_file_h->e_shentsize * (nn)))
>>>
>>>> Are you connected on freenode #emacs.
>>> No.
>> First of all thank you for your time.
>> Well,
>> (gdb) p (*(ElfW (Shdr) *) ((byte *) new_section_h +
>> new_file_h->e_shentsize * (nn)))
>> No symbol "ElfW" in current context.
>> (gdb)
>> Also ElfBitsW does not exists.
>> (gdb) p ElfBitsW
>> No symbol "ElfBitsW" in current context.
>> (gdb)
> You need to expand all these macros by hand. They are defined at the
> beginning of unexelf.c:
>
> #ifndef ElfW
> # define ElfBitsW(bits, type) Elf##bits##_##type
> # ifndef ELFSIZE
> # ifdef _LP64
> # define ELFSIZE 64
> # else
> # define ELFSIZE 32
> # endif
> # endif
> /* This macro expands `bits' before invoking ElfBitsW. */
> # define ElfExpandBitsW(bits, type) ElfBitsW (bits, type)
> # define ElfW(type) ElfExpandBitsW (ELFSIZE, type)
> #endif
>
> I would suggest at first to rebuild Emacs with "-gdwarf-4 -g3"
> compiler switches, maybe that will allow you to type expressions with
> macros, and let GDB expand them using the debug info. Maybe.
Well, finally I have got it.
(gdb) p (*(ElfW (Shdr) *) ((byte *) new_section_h +
new_file_h->e_shentsize * (nn)))
$1 = {sh_name = 1735746149, sh_type = 1650614623, sh_flags =
7090183337103746418, sh_addr = 28550371716589429, sh_offset =
8313477191008871470, sh_size = 8458434531098129012,
sh_link = 1634885479, sh_info = 1936025454, sh_addralign =
6874592421672660480, sh_entsize = 478660485485}
(gdb) p old_section_names + NEW_SECTION_H (nn).sh_name
$2 = 0x4000128ceb51 <Address 0x4000128ceb51 out of bounds>
(gdb) p old_section_names
$3 = 0x3fffab1788ec ""
(gdb)
Hope it helps.
--
Petr Hracek
Software Engineer
Developer Experience
Red Hat, Inc
Mob: +420777056169
email: phracek@redhat.com
next prev parent reply other threads:[~2015-10-05 9:16 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-20 7:56 bug#20614: Segmentation fault when building on Power8 Little Endian Petr Hracek
2015-05-20 14:45 ` Eli Zaretskii
2015-05-20 16:12 ` Glenn Morris
2015-05-21 12:55 ` Petr Hracek
2015-07-13 11:27 ` Petr Hracek
2015-07-13 13:16 ` Andreas Schwab
2015-07-14 7:52 ` Petr Hracek
2015-07-14 8:14 ` Andreas Schwab
2015-09-16 11:28 ` Petr Hracek
2015-09-22 10:17 ` Petr Hracek
2015-09-23 8:06 ` Petr Hracek
2015-09-23 9:34 ` Eli Zaretskii
2015-09-23 11:00 ` Petr Hracek
2015-09-23 11:14 ` Eli Zaretskii
2015-09-23 12:11 ` Petr Hracek
2015-09-23 12:23 ` Eli Zaretskii
2015-09-24 11:04 ` Petr Hracek
2015-09-24 15:32 ` Eli Zaretskii
2015-09-24 17:56 ` Petr Hracek
2015-09-26 7:58 ` Eli Zaretskii
2015-09-30 10:39 ` Petr Hracek
2015-10-01 7:43 ` Eli Zaretskii
2015-10-01 8:46 ` Petr Hracek
2015-10-01 11:44 ` Petr Hracek
2015-10-01 11:53 ` Petr Hracek
2015-10-01 12:22 ` Eli Zaretskii
2015-10-01 14:05 ` Petr Hracek
2015-10-01 16:01 ` Eli Zaretskii
2015-10-02 8:36 ` Petr Hracek
2015-10-02 8:49 ` Eli Zaretskii
2015-10-02 12:58 ` Petr Hracek
2015-10-02 13:46 ` Eli Zaretskii
2015-10-05 7:40 ` Petr Hracek
2015-10-05 8:27 ` Eli Zaretskii
2015-10-05 9:16 ` Petr Hracek [this message]
2015-10-05 9:39 ` Eli Zaretskii
2015-10-05 11:23 ` Petr Hracek
2015-10-05 11:40 ` Eli Zaretskii
2015-10-05 14:07 ` Petr Hracek
2015-10-05 16:52 ` Eli Zaretskii
2015-10-06 8:41 ` Petr Hracek
2015-10-06 11:52 ` Petr Hracek
2015-10-06 14:55 ` Eli Zaretskii
2015-10-07 8:17 ` Petr Hracek
2015-10-07 10:56 ` YAMAMOTO Mitsuharu
2015-10-07 12:26 ` Petr Hracek
2015-10-08 0:54 ` YAMAMOTO Mitsuharu
2015-10-08 13:27 ` Jaromir Capik
2015-10-10 1:40 ` YAMAMOTO Mitsuharu
2015-10-10 15:44 ` Andreas Schwab
2015-10-13 7:30 ` Petr Hracek
2015-10-13 8:30 ` Andreas Schwab
2015-10-16 15:24 ` Jaromir Capik
2015-10-19 7:20 ` Andreas Schwab
2015-09-23 12:10 ` Petr Hracek
2015-09-23 12:21 ` Eli Zaretskii
2015-09-23 13:10 ` Petr Hracek
2015-09-23 13:38 ` Petr Hracek
2015-09-23 13:57 ` Eli Zaretskii
2015-09-23 17:25 ` Glenn Morris
2015-09-23 17:47 ` Glenn Morris
2015-09-29 8:15 ` Florian Weimer
2015-07-13 12:17 ` bug#20614: Segmentation fault when building on Power8 Little Endian (ppc64le) Petr Hracek
2015-11-17 1:59 ` bug#20614: alignment problem with recent Emacs unexelf.c changes Paul Eggert
2015-11-17 9:03 ` Alan Modra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=56123FF0.3040104@redhat.com \
--to=phracek@redhat.com \
--cc=20614@debbugs.gnu.org \
--cc=eliz@gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.