1 files changed, 13 insertions, 0 deletions

diff --git a/include/asm-i386/system.h b/include/asm-i386/system.h
index 772f85da1206..88b4d5c6f37a 100644
--- a/include/asm-i386/system.h
+++ b/include/asm-i386/system.h
@@ -140,6 +140,19 @@ static inline unsigned long _get_base(char * addr)
                 :"=r" (__dummy)); \
         __dummy; \
 })
+
+#define read_cr4_safe() ({                            \
+        unsigned int __dummy;                         \
+        /* This could fault if %cr4 does not exist */ \
+        __asm__("1: movl %%cr4, %0              \n"   \
+                "2:                             \n"   \
+                ".section __ex_table,\"a\"      \n"   \
+                ".long 1b,2b                    \n"   \
+                ".previous                      \n"   \
+                : "=r" (__dummy): "0" (0));           \
+        __dummy;                                      \
+})
+
 #define write_cr4(x) \
         __asm__ __volatile__("movl %0,%%cr4": :"r" (x));
 #define stts() write_cr0(8 | read_cr0())