x86, kaslr: Provide randomness functions

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

diff --git a/arch/x86/include/asm/archrandom.h b/arch/x86/include/asm/archrandom.h
index 0d9ec77..e6a9245 100644 (file)
--- a/arch/x86/include/asm/archrandom.h
+++ b/arch/x86/include/asm/archrandom.h
@@ -39,6 +39,20 @@
 
 #ifdef CONFIG_ARCH_RANDOM
 
+/* Instead of arch_get_random_long() when alternatives haven't run. */
+static inline int rdrand_long(unsigned long *v)
+{
+       int ok;
+       asm volatile("1: " RDRAND_LONG "\n\t"
+                    "jc 2f\n\t"
+                    "decl %0\n\t"
+                    "jnz 1b\n\t"
+                    "2:"
+                    : "=r" (ok), "=a" (*v)
+                    : "0" (RDRAND_RETRY_LOOPS));
+       return ok;
+}
+
 #define GET_RANDOM(name, type, rdrand, nop)                    \
 static inline int name(type *v)                                        \
 {                                                              \
@@ -68,6 +82,13 @@ GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP3);
 
 #endif /* CONFIG_X86_64 */
 
+#else
+
+static inline int rdrand_long(unsigned long *v)
+{
+       return 0;
+}
+
 #endif  /* CONFIG_ARCH_RANDOM */
 
 extern void x86_init_rdrand(struct cpuinfo_x86 *c);