Bug 1528418 – glibc: Merge error in XSAVE dynamic linker trampoline patch

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Bug 1528418 - glibc: Merge error in XSAVE dynamic linker trampoline patch

Summary:	glibc: Merge error in XSAVE dynamic linker trampoline patch

Status:	CLOSED ERRATA

Aliases:	None

Product:	Red Hat Enterprise Linux 7
Classification:	Red Hat
Component:	glibc (Show other bugs)
Sub Component:
Version:	7.5
Hardware:	x86_64 Unspecified

Priority	unspecified Severity unspecified
Target Milestone:	rc
Target Release:	---
Assigned To:	Carlos O'Donell
QA Contact:	Sergey Kolosov
Docs Contact:

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Reported:	2017-12-21 14:44 EST by Florian Weimer
Modified:	2018-04-10 10:04 EDT (History)
CC List:	8 users (show)

See Also:	1504969 1499012 1527587 1513070
Fixed In Version:	glibc-2.17-221.el7
Doc Type:	Bug Fix
Doc Text:	Previously, the dynamic loader in the GNU C library (glibc) contained an optimization which avoided saving and restoring vector registers for 64-bit Intel and AMD architectures. Consequently, applications compiled for these architectures and using unsupported vector registers for passing function arguments, not adhering to the published x86-64 psABI specification, could fail and produce unexpected results. This update changes the dynamic loader to use the XSAVE/XSAVEC context switch CPU instructions, preserving more CPU state, including all vector registers. As a result, applications using vector registers for argument passing, in ways which are not supported by the x86-64 psABI specification, work again.
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Last Closed:	2018-04-10 10:04:32 EDT
Type:	Bug
Regression:	---
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Documentation:	---
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oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
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External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Sourceware	22641	None	None	None	2017-12-21 15:08 EST
Red Hat Product Errata	RHSA-2018:0805	None	None	None	2018-04-10 10:04 EDT

Groups: None (edit)

Description Florian Weimer 2017-12-21 14:44:31 EST

As explained in bug 1527587 comment 8, the code which selects the XSAVE trampoline is nested incorrectly and is only active the CPU supports AVX.

We are investigating if the use of FXSAVE instead of XSAVE causes any issues on CPUs supported by Red Hat Enterprise Linux.  But we should fix the oversight independently of that.

Comment 7 errata-xmlrpc 2018-04-10 10:04:32 EDT

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2018:0805

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