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-rw-r--r--arch/x86/include/asm/uaccess_64.h11
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index 8e796fb..d8def8b 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -17,6 +17,8 @@
/* 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);
__must_check unsigned long
copy_user_generic_unrolled(void *to, const void *from, unsigned len);
@@ -26,9 +28,16 @@ copy_user_generic(void *to, const void *from, unsigned len)
{
unsigned ret;
- alternative_call(copy_user_generic_unrolled,
+ /*
+ * If CPU has ERMS feature, use copy_user_enhanced_fast_string.
+ * Otherwise, if CPU has rep_good feature, use copy_user_generic_string.
+ * 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,
ASM_OUTPUT2("=a" (ret), "=D" (to), "=S" (from),
"=d" (len)),
"1" (to), "2" (from), "3" (len)