From: Pedro Alves <palves@redhat.com>
To: Pierre Muller <pierre.muller@ics-cnrs.unistra.fr>
Cc: "'Joel Brobecker'" <brobecker@adacore.com>, gdb-patches@sourceware.org
Subject: Re: [RFA-v2] Fix PR 16201: internal error on a cygwin program linked against a DLL with no .data section
Date: Fri, 20 Dec 2013 18:19:00 -0000 [thread overview]
Message-ID: <52B48A28.2000402@redhat.com> (raw)
In-Reply-To: <52ab7ec0.c8da420a.12c6.ffffb3f4SMTPIN_ADDED_BROKEN@mx.google.com>
On 12/13/2013 09:39 PM, Pierre Muller wrote:
>
>> I just re-read the code, and I really think it would be better if
>> someone who actually understands the general framework could comment.
>> The problem seems, as you stated, relatively well understood, but
>> I am not sure how we are expected to fix it.
>>
>>> 2013-11-27 Pierre Muller <muller@sourceware.org>
>>>
>>> PR 16201
>>> coff-pe-read.c (read_pe_exported_syms): Set sect_index_text,
Missing '*'
>>> sect_index_data and sect_index_bss of objfile struct, even if
>>> there is no canonical '.text', '.data' or '.bss' named
>> section.
>>
>> My only comment is that the patch could gain from some additional
>> comments explaining _why_ you're forcing the sect_index field
>> ("event if already set before"), and what you are trying to achieve.
>
> Here is a new version in which I try to explain
> more clearly that if we find the canonical
> '.text', '.data' or '.bss' section names,
> we should use these sections to set sect_index_XXX.
> Otherwise, we use the first section that is used later with
> for which we set ms_type to mst_XXX to also set sect_index_XXX.
> This ensure that sect_index_XXX is always set if
> any exported symbol is in inserted using
> prim_rcord_minimal_symbol with ms_type parameter set to mst_XXX
>
> I hope this clarifies the patch .
>
So in the DLL in question, there was no .data section, but
there was another section with IMAGE_SCN_CNT_INITIALIZED_DATA set.
What was this section? From the PR:
$ objdump -h icudt49.dll
icudt49.dll: file format pei-i386
Sections:
Idx Name Size VMA LMA File off Algn
0 .rdata 0111f4fa 10001000 10001000 00000400 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
1 .rsrc 00000458 11121000 11121000 0111fa00 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
From the PR, we see the dll exported a icudt49_dat symbol:
...
#1 0x0054ae16 in prim_record_minimal_symbol (name=name@entry=0x8019db78 "icudt49!icudt49_dat",
address=address@entry=1585713152, ms_type=mst_data,
objfile=objfile@entry=0x8027a9c8)
...
So the fix is this part:
else if (characteristics & IMAGE_SCN_CNT_INITIALIZED_DATA)
- section_data[otherix].ms_type = mst_data;
+ {
+ section_data[otherix].ms_type = mst_data;
+ if (objfile->sect_index_data == -1)
+ objfile->sect_index_data = otherix;
+ }
It's not clear to me that forcing sect_index_... when the
canonical section is found is better than using the
first / lowest section that looks like code/data/bss. I'd
suggest just taking the first found. IOW, do:
if (objfile->sect_index_data == -1)
objfile->sect_index_data = otherix;
in the other branch too.
But, hmmm, don't we know the symbol's section?
Wouldn't it be even better to make add_pe_exported_sym
call prim_record_minimal_symbol_and_info directly,
rather than prim_record_minimal_symbol ?
--
Pedro Alves
next prev parent reply other threads:[~2013-12-20 18:19 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-11 10:50 [PING RFA] " Pierre Muller
2013-12-11 17:02 ` Joel Brobecker
2013-12-13 21:40 ` [RFA-v2] " Pierre Muller
2013-12-18 3:55 ` Joel Brobecker
[not found] ` <52ab7ec0.c8da420a.12c6.ffffb3f4SMTPIN_ADDED_BROKEN@mx.google.com>
2013-12-20 18:19 ` Pedro Alves [this message]
2013-12-22 22:56 ` Pierre Muller
[not found] ` <15250.2735647888$1387752987@news.gmane.org>
2013-12-23 2:31 ` asmwarrior
[not found] ` <52b76e14.8886420a.29e6.ffffddb2SMTPIN_ADDED_BROKEN@mx.google.com>
2014-01-06 18:34 ` Pedro Alves
2014-01-07 11:15 ` [RFA-v3] " Pierre Muller
[not found] ` <52cbe1c5.67ed440a.67e6.7288SMTPIN_ADDED_BROKEN@mx.google.com>
2014-01-07 20:58 ` Pedro Alves
2014-01-07 23:40 ` [COMMIT-v4] " Pierre Muller
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