[Xen-changelog] [xen master] x86emul: correct stub invocation constraints

[patchbot@xxxxxxx]

commit cd91ab08eaa23409440ef6b4f5ad6e651b629c3b
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Apr 26 09:49:24 2017 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Apr 26 09:49:24 2017 +0200

    x86emul: correct stub invocation constraints
    
    Stub invocations need to have the space the stub occupies as an input,
    to prevent the compiler from re-ordering (or omitting) writes to it.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Release-acked-by: Julien Grall <julien.grall@xxxxxxx>
---
 xen/arch/x86/x86_emulate/x86_emulate.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index c822221..a695d5a 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -837,7 +837,8 @@ do{ asm volatile (                                          
            \
                    ".popsection\n\t"                                    \
                    _ASM_EXTABLE(.Lret%=, .Lfix%=)                       \
                    : [exn] "+g" (res_), constraints,                    \
-                     [stub] "rm" (stub.func) );                         \
+                     [stub] "rm" (stub.func),                           \
+                     "m" (*(uint8_t(*)[MAX_INST_LEN + 1])stub.ptr) );   \
     if ( unlikely(~res_.raw) )                                          \
     {                                                                   \
         gprintk(XENLOG_WARNING,                                         \
@@ -853,7 +854,8 @@ do{ asm volatile (                                          
            \
 #else
 # define invoke_stub(pre, post, constraints...)                         \
     asm volatile ( pre "\n\tcall *%[stub]\n\t" post                     \
-                   : constraints, [stub] "rm" (stub.func) )
+                   : constraints, [stub] "rm" (stub.func),              \
+                     "m" (*(uint8_t(*)[MAX_INST_LEN + 1])stub.buf) )
 #endif
 
 #define emulate_stub(dst, src...) do {                                  \
--
generated by git-patchbot for /home/xen/git/xen.git#master

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