x86/mm/pkeys: Add functions to fetch PKRU

[cascardo/linux.git] / arch / x86 / include / asm / special_insns.h

diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
index 2270e41..aee6e76 100644 (file)
--- a/arch/x86/include/asm/special_insns.h
+++ b/arch/x86/include/asm/special_insns.h
@@ -98,6 +98,28 @@ static inline void native_write_cr8(unsigned long val)
 }
 #endif
 
+#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
+static inline u32 __read_pkru(void)
+{
+       u32 ecx = 0;
+       u32 edx, pkru;
+
+       /*
+        * "rdpkru" instruction.  Places PKRU contents in to EAX,
+        * clears EDX and requires that ecx=0.
+        */
+       asm volatile(".byte 0x0f,0x01,0xee\n\t"
+                    : "=a" (pkru), "=d" (edx)
+                    : "c" (ecx));
+       return pkru;
+}
+#else
+static inline u32 __read_pkru(void)
+{
+       return 0;
+}
+#endif
+
 static inline void native_wbinvd(void)
 {
        asm volatile("wbinvd": : :"memory");