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* [Bug libc/17259] New: sysdeps/x86_64/cacheinfo.c:intel_check_word corrupts rbx and another register
@ 2014-08-11 23:29 pageexec at gmail dot com
2014-08-12 16:04 ` [Bug libc/17259] sysdeps/x86_64/cacheinfo.c:intel_check_word may corrupt rbx hjl.tools at gmail dot com
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: pageexec at gmail dot com @ 2014-08-11 23:29 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=17259
Bug ID: 17259
Summary: sysdeps/x86_64/cacheinfo.c:intel_check_word corrupts
rbx and another register
Product: glibc
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: libc
Assignee: unassigned at sourceware dot org
Reporter: pageexec at gmail dot com
CC: drepper.fsp at gmail dot com
the inline asm invoking cpuid tries to save/restore rbx itself but unlike its
i386 version, this one will actually corrupt (zero out) the top 32 bits of both
rbx and whatever register gets assigned to %1 due to the "xchg ebx,%1". this
code was probably simply copy-pasted from the i386 version. note that the same
file actually contains a proper implementation of cpuid as the __cpuid_count
macro that had been there some 2 years before this new and buggy 'invention'.
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* [Bug libc/17259] sysdeps/x86_64/cacheinfo.c:intel_check_word may corrupt rbx
2014-08-11 23:29 [Bug libc/17259] New: sysdeps/x86_64/cacheinfo.c:intel_check_word corrupts rbx and another register pageexec at gmail dot com
@ 2014-08-12 16:04 ` hjl.tools at gmail dot com
2014-08-13 0:06 ` cvs-commit at gcc dot gnu.org
2014-08-13 0:07 ` hjl.tools at gmail dot com
2 siblings, 0 replies; 4+ messages in thread
From: hjl.tools at gmail dot com @ 2014-08-12 16:04 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=17259
H.J. Lu <hjl.tools at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |hjl.tools at gmail dot com
Summary|sysdeps/x86_64/cacheinfo.c: |sysdeps/x86_64/cacheinfo.c:
|intel_check_word corrupts |intel_check_word may
|rbx and another register |corrupt rbx
--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> ---
There are
asm volatile ("xchgl %%ebx, %1; cpuid; xchgl %%ebx, %1"
: "=a" (eax), "=r" (ebx), "=c" (ecx), "=d" (edx)
: "0" (4), "2" (round));
The only register compiler is aware of is RBX. No other registers are
impacted. We are lucky that it doesn't cause any problems since RBX
is also used by compiler for other purposes so that RBX is saved and
restored in intel_check_word. We should just use __cpuid_count instead.
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* [Bug libc/17259] sysdeps/x86_64/cacheinfo.c:intel_check_word may corrupt rbx
2014-08-11 23:29 [Bug libc/17259] New: sysdeps/x86_64/cacheinfo.c:intel_check_word corrupts rbx and another register pageexec at gmail dot com
2014-08-12 16:04 ` [Bug libc/17259] sysdeps/x86_64/cacheinfo.c:intel_check_word may corrupt rbx hjl.tools at gmail dot com
@ 2014-08-13 0:06 ` cvs-commit at gcc dot gnu.org
2014-08-13 0:07 ` hjl.tools at gmail dot com
2 siblings, 0 replies; 4+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2014-08-13 0:06 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=17259
--- Comment #2 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "GNU C Library master sources".
The branch, master has been updated
via b4acef1ffe2e1ba6c608f31c1954a8100d3eabb0 (commit)
from 61b1ef6e7cc4518cdadb808dfa78980cc15a63c3 (commit)
Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.
- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b4acef1ffe2e1ba6c608f31c1954a8100d3eabb0
commit b4acef1ffe2e1ba6c608f31c1954a8100d3eabb0
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Tue Aug 12 17:02:51 2014 -0700
Replace cpuid asm statement with __cpuid_count
The compiler doesn't know that the cpuid asm statement in intel_check_word
will trash RBX. We are lucky that it doesn't cause any problems since
RBX is also used by compiler for other purposes so that RBX is saved and
restored. This patch replaces it with __cpuid_count.
[BZ #17259]
* sysdeps/x86_64/cacheinfo.c (intel_check_word): Replace cpuid
asm statement with __cpuid_count.
-----------------------------------------------------------------------
Summary of changes:
ChangeLog | 6 ++++++
NEWS | 3 ++-
sysdeps/x86_64/cacheinfo.c | 4 +---
3 files changed, 9 insertions(+), 4 deletions(-)
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* [Bug libc/17259] sysdeps/x86_64/cacheinfo.c:intel_check_word may corrupt rbx
2014-08-11 23:29 [Bug libc/17259] New: sysdeps/x86_64/cacheinfo.c:intel_check_word corrupts rbx and another register pageexec at gmail dot com
2014-08-12 16:04 ` [Bug libc/17259] sysdeps/x86_64/cacheinfo.c:intel_check_word may corrupt rbx hjl.tools at gmail dot com
2014-08-13 0:06 ` cvs-commit at gcc dot gnu.org
@ 2014-08-13 0:07 ` hjl.tools at gmail dot com
2 siblings, 0 replies; 4+ messages in thread
From: hjl.tools at gmail dot com @ 2014-08-13 0:07 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=17259
H.J. Lu <hjl.tools at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Version|unspecified |2.20
Resolution|--- |FIXED
Target Milestone|--- |2.20
--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> ---
Fixed for 2.20.
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end of thread, other threads:[~2014-08-13 0:07 UTC | newest]
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2014-08-11 23:29 [Bug libc/17259] New: sysdeps/x86_64/cacheinfo.c:intel_check_word corrupts rbx and another register pageexec at gmail dot com
2014-08-12 16:04 ` [Bug libc/17259] sysdeps/x86_64/cacheinfo.c:intel_check_word may corrupt rbx hjl.tools at gmail dot com
2014-08-13 0:06 ` cvs-commit at gcc dot gnu.org
2014-08-13 0:07 ` hjl.tools at gmail dot com
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