From: "Jan Beulich" <JBeulich@suse.com>
To: xen-devel <xen-devel@lists.xenproject.org>
Cc: George Dunlap <George.Dunlap@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Julien Grall <julien.grall@arm.com>
Subject: [PATCH] x86emul: keep compiler from using {x, y, z}mm registers itself
Date: Mon, 16 Oct 2017 06:32:24 -0600 [thread overview]
Message-ID: <59E4C2F80200007800186B29@prv-mh.provo.novell.com> (raw)
Since the emulator acts on the live hardware registers, we need to
prevent the compiler from using them e.g. for inlined memcpy() /
memset() (as gcc7 does). We can't, however, set this from the command
line, as otherwise the 64-bit build would face issues with functions
returning floating point values and being declared in standard headers.
As the pragma isn't available prior to gcc6, we need to invoke it
conditionally. Luckily up to gcc6 we haven't seen generated code access
SIMD registers beyond what our asm()s do.
Reported-by: George Dunlap <george.dunlap@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
While this doesn't affect core functionality, I think it would still be
nice for it to be allowed in for 4.10.
--- a/tools/tests/x86_emulator/x86-emulate.h
+++ b/tools/tests/x86_emulator/x86-emulate.h
@@ -4,6 +4,11 @@
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
+
+#if __GNUC__ >= 6
+#pragma GCC target("no-sse")
+#endif
+
#include <xen/xen.h>
#include <asm/msr-index.h>
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next reply other threads:[~2017-10-16 12:32 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-16 12:32 Jan Beulich [this message]
2017-10-16 12:37 ` [PATCH] x86emul: keep compiler from using {x, y, z}mm registers itself Andrew Cooper
2017-10-16 12:42 ` Jan Beulich
2017-11-06 11:59 ` Ping: " Jan Beulich
2017-11-06 15:04 ` George Dunlap
2017-11-13 16:22 ` Julien Grall
2017-11-21 13:26 ` Ping#2: " Jan Beulich
2017-11-21 13:29 ` Andrew Cooper
2017-11-22 16:09 ` Julien Grall
2017-10-16 15:05 ` George Dunlap
2017-10-16 15:44 ` Jan Beulich
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