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[Bug gdb/17407] Regression for Linux vDSO reading
- From: "cvs-commit at gcc dot gnu.org" <sourceware-bugzilla at sourceware dot org>
- To: gdb-prs at sourceware dot org
- Date: Thu, 18 Sep 2014 06:29:15 +0000
- Subject: [Bug gdb/17407] Regression for Linux vDSO reading
- Auto-submitted: auto-generated
- References: <bug-17407-4717 at http dot sourceware dot org/bugzilla/>
https://sourceware.org/bugzilla/show_bug.cgi?id=17407
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https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=54fbc750b54271efb75ae11ce49f14c4234a9476
commit 54fbc750b54271efb75ae11ce49f14c4234a9476
Author: Jan Kratochvil <jan.kratochvil@redhat.com>
Date: Thu Sep 18 08:21:40 2014 +0200
Fix regression for Linux vDSO in GDB (PR gdb/17407).
since
5979d6b69b20a8355ea94b75fad97415fce4788c
https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=5979d6b69b20a8355ea94b75fad97415fce4788c
vdso handling
https://sourceware.org/ml/binutils/2014-03/msg00082.html
https://sourceware.org/ml/binutils/2014-04/msg00003.html
Message-ID:
<A78C989F6D9628469189715575E55B230AA884EB@IRSMSX104.ger.corp.intel.com>
I get on
kernel-3.16.2-200.fc20.x86_64
https://koji.fedoraproject.org/koji/buildinfo?buildID=575860
attaching its vdso.bin.gz
GDB (FSF HEAD 5e43d46791c4c66fd83947a12d4f716b561a9103) regression:
reproducer:
./gdb -ex start ./gdb
actual result / FAIL:
Got object file from memory but can't read symbols: File truncated.
expected result / PASS:
<nothing>
or / PASS:
warning: Could not load shared library symbols for linux-vdso.so.1.
Do you need "set solib-search-path" or "set sysroot"?
That "warning: Could not load shared library..." is mostly harmless (it is
a bug in GDB), in the FAIL case it is not printed just because
bfd_check_format() fails there.
It seems logical to me this way when the 'size' parameter has been already
added.
Alan Modra:
I was wrongly thinking that the section headers were
always last when I wrote that code. (They are now! If you relink
that vdso with current binutils master you won't hit this problem, but
that of course doesn't help existing kernels.)
I do not see a regression for add-symbol-file-from-memory for
libncurses.so.5
from the original thread above.
Start of section headers: 1080 (bytes into file)
Size of section headers: 64 (bytes)
Number of section headers: 13
Section header string table index: 8
Section Headers:
[Nr] Name Type Address Off Size ES
Flg Lk Inf Al
[ 8] .fake_shstrtab STRTAB 0000000000000780 000780 000076 00
A 0 0 32
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz
MemSiz Flg Align
LOAD 0x000000 0x0000000000000000 0x0000000000000000 0x0012fe
0x0012fe R E 0x1000
size == 0x2000
shdr_end == 0x778 == 1080 + 13 * 64
high_offset == 0x12fe
else if (size >= shdr_end)
- high_offset = shdr_end;
+ high_offset = size;
But then 0x778 < 0x780 for "Section header string table index" so whole
bfd_check_format() fails because section headers were not cleared here:
/* If the segments visible in memory didn't include the section headers,
then clear them from the file header. */
if (high_offset < shdr_end)
bfd/ChangeLog
2014-09-18 Jan Kratochvil <jan.kratochvil@redhat.com>
PR gdb/17407
* elfcode.h (bfd_from_remote_memory): Use SIZE for HIGH_OFFSET.
-----------------------------------------------------------------------
Summary of changes:
bfd/ChangeLog | 5 +++++
bfd/elfcode.h | 2 +-
2 files changed, 6 insertions(+), 1 deletions(-)
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