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List:       xen-cvs
Subject:    [Xen-changelog] [xen stable-4.8] x86/entry: Use 32bit xors rater than 64bit xors for clearing GPRs
From:       patchbot () xen ! org
Date:       2018-03-29 1:23:23
Message-ID: E1f1MHj-0006oG-Vw () xenbits ! xenproject ! org
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commit bc8aa42842f94561a5e2555b042de5e5dec56c88
Author:     Andrew Cooper <andrew.cooper3@citrix.com>
AuthorDate: Tue Mar 6 16:12:31 2018 +0100
Commit:     Jan Beulich <jbeulich@suse.com>
CommitDate: Tue Mar 6 16:12:31 2018 +0100

    x86/entry: Use 32bit xors rater than 64bit xors for clearing GPRs
    
    Intel's Silvermont/Knights Landing architecture treats them as full ALU
    operations, rather than zeroing idoms.
    
    No functional change, and no change in code volume (only changing the bit
    selection in the REX prefix).
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
    Acked-by: Jan Beulich <jbeulich@suse.com>
    master commit: eb1d3a3f04b85d596862a4c9dcf796e67ab4dc09
    master date: 2018-02-15 11:08:27 +0000
---
 xen/include/asm-x86/asm_defns.h | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/xen/include/asm-x86/asm_defns.h b/xen/include/asm-x86/asm_defns.h
index d42c85899d..0c22e3dcf0 100644
--- a/xen/include/asm-x86/asm_defns.h
+++ b/xen/include/asm-x86/asm_defns.h
@@ -271,10 +271,10 @@ static always_inline void stac(void)
         movq  %r10,UREGS_r10(%rsp)
         movq  %r11,UREGS_r11(%rsp)
 .endif
-        xor   %r8, %r8
-        xor   %r9, %r9
-        xor   %r10, %r10
-        xor   %r11, %r11
+        xor   %r8d, %r8d
+        xor   %r9d, %r9d
+        xor   %r10d, %r10d
+        xor   %r11d, %r11d
         movq  %rbx,UREGS_rbx(%rsp)
         xor   %ebx, %ebx
         movq  %rbp,UREGS_rbp(%rsp)
@@ -291,10 +291,10 @@ static always_inline void stac(void)
         movq  %r14,UREGS_r14(%rsp)
         movq  %r15,UREGS_r15(%rsp)
 .endif
-        xor   %r12, %r12
-        xor   %r13, %r13
-        xor   %r14, %r14
-        xor   %r15, %r15
+        xor   %r12d, %r12d
+        xor   %r13d, %r13d
+        xor   %r14d, %r14d
+        xor   %r15d, %r15d
 .endm
 
 #define LOAD_ONE_REG(reg, compat) \
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.8

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