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From: "hjl.tools at gmail dot com" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug libc/17259] sysdeps/x86_64/cacheinfo.c:intel_check_word may corrupt rbx
Date: Tue, 12 Aug 2014 16:04:00 -0000 [thread overview]
Message-ID: <bug-17259-131-kbsW6830rb@http.sourceware.org/bugzilla/> (raw)
In-Reply-To: <bug-17259-131@http.sourceware.org/bugzilla/>
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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next prev parent reply other threads:[~2014-08-12 16:04 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
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 [this message]
2014-08-13 0:06 ` [Bug libc/17259] sysdeps/x86_64/cacheinfo.c:intel_check_word may corrupt rbx cvs-commit at gcc dot gnu.org
2014-08-13 0:07 ` hjl.tools at gmail dot com
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