x86: don't use REP_GOOD or ERMS for user memory copies

The modern target to use is FSRM (Fast Short REP MOVS), and the other
cases should only be used for bigger areas (ie mainly things like page
clearing).

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 10 deletions

diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index d13d71af5cf6..c697cf10b7c8 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -18,9 +18,7 @@
 
 /* Handles exceptions in both to and from, but doesn't do access_ok */
 __must_check unsigned long
-copy_user_enhanced_fast_string(void *to, const void *from, unsigned len);
-__must_check unsigned long
-copy_user_generic_string(void *to, const void *from, unsigned len);
+copy_user_fast_string(void *to, const void *from, unsigned len);
 __must_check unsigned long
 copy_user_generic_unrolled(void *to, const void *from, unsigned len);
 
@@ -30,15 +28,12 @@ copy_user_generic(void *to, const void *from, unsigned len)
 	unsigned ret;
 
 	/*
-	 * If CPU has ERMS feature, use copy_user_enhanced_fast_string.
-	 * Otherwise, if CPU has rep_good feature, use copy_user_generic_string.
+	 * If CPU has FSRM feature, use 'rep movs'.
 	 * Otherwise, use copy_user_generic_unrolled.
 	 */
-	alternative_call_2(copy_user_generic_unrolled,
-			 copy_user_generic_string,
-			 X86_FEATURE_REP_GOOD,
-			 copy_user_enhanced_fast_string,
-			 X86_FEATURE_ERMS,
+	alternative_call(copy_user_generic_unrolled,
+			 copy_user_fast_string,
+			 X86_FEATURE_FSRM,
 			 ASM_OUTPUT2("=a" (ret), "=D" (to), "=S" (from),
 				     "=d" (len)),
 			 "1" (to), "2" (from), "3" (len)