[xen staging] x86/string: correct memmove()'s forwarding to memcpy()

[patchbot@xxxxxxx]

commit 7b93d92a35dc7c0a6e5f1f79b3c887aa3e66ddc0
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Thu Feb 4 13:59:56 2021 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Feb 4 13:59:56 2021 +0100

    x86/string: correct memmove()'s forwarding to memcpy()
    
    With memcpy() expanding to the compiler builtin, we may not hand it
    overlapping source and destination. We strictly mean to forward to our
    own implementation (a few lines up in the same source file).
    
    Fixes: 78825e1c60fa ("x86/string: Clean up x86/string.h")
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/string.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/string.c b/xen/arch/x86/string.c
index e2f84638c4..bda24b14ac 100644
--- a/xen/arch/x86/string.c
+++ b/xen/arch/x86/string.c
@@ -43,7 +43,8 @@ void *(memmove)(void *dest, const void *src, size_t n)
         return dest;
 
     if ( dest < src )
-        return memcpy(dest, src, n);
+        /* Depends on Xen's implementation operating forwards. */
+        return (memcpy)(dest, src, n);
 
     asm volatile (
         "   std         ; "
--
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