This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: bndmov MPX instructions in dynamic linker breaks valgrind
- From: Florian Weimer <fweimer at redhat dot com>
- To: Roland McGrath <roland at hack dot frob dot com>, Markus Trippelsdorf <markus at trippelsdorf dot de>
- Cc: libc-alpha at sourceware dot org, Igor Zamyatin <igor dot zamyatin at intel dot com>
- Date: Thu, 07 Aug 2014 09:30:58 +0200
- Subject: Re: bndmov MPX instructions in dynamic linker breaks valgrind
- Authentication-results: sourceware.org; auth=none
- References: <20140802175103 dot GC294 at x4> <20140806211851 dot D3F5A2C3983 at topped-with-meat dot com>
On 08/06/2014 11:18 PM, Roland McGrath wrote:
Because of Intel's assurance that the new opcode values are harmless NOPs,
we didn't put any provision in the source for building a libc without the
MPX support.
How confident are we that existing silicon is able to decode these NOPs
efficiently? Executing them as NOPs is just one part—if there's a
significant performance hit, we have a problem as well.
--
Florian Weimer / Red Hat Product Security