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[Bug libc/13583] New: AVX check not done correctly for strcasecmp
- From: "delroth at gmail dot com" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sources dot redhat dot com
- Date: Wed, 11 Jan 2012 14:13:04 +0000
- Subject: [Bug libc/13583] New: AVX check not done correctly for strcasecmp
- Auto-submitted: auto-generated
http://sourceware.org/bugzilla/show_bug.cgi?id=13583
Bug #: 13583
Summary: AVX check not done correctly for strcasecmp
Product: glibc
Version: 2.15
Status: NEW
Severity: normal
Priority: P2
Component: libc
AssignedTo: drepper.fsp@gmail.com
ReportedBy: delroth@gmail.com
Classification: Unclassified
According to Intel manuals, checking for AVX has to be done by checking AVX and
OS XSAVE support in CPUID + XFEATURE_ENABLED_MASK via xgetbv. However, for
strcasecmp, AVX is checked by testing the AVX bit in the cpuid.
This makes systems using glibc-2.15 unbootable under current versions of Xen
when the CPU supports AVX because Xen does not have XSAVE support. On these
systems, strcasecmp fails with a SIGILL when executing vmovdqa.
Bad check is here:
http://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/x86_64/multiarch/strcmp.S;h=f93c83d7d469085029018dcf0d7f2eaadb05a44f;hb=HEAD#l108
Example of a good check:
http://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/x86_64/dl-trampoline.S;h=6523c92945a59e6a5eefa3cfb2e0c58dfa99fd44;hb=HEAD#l137
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