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authorKees Cook <keescook@chromium.org>2013-10-11 04:18:15 +0400
committerH. Peter Anvin <hpa@linux.intel.com>2013-10-13 14:12:12 +0400
commit5bfce5ef55cbe78ee2ee6e97f2e26a8a582008f3 (patch)
treeead4a5281554b6f2e0a334cc7e1d83dccf35e15c /arch/x86/include/asm/archrandom.h
parent8ab3820fd5b2896d66da7bb2a906bc382e63e7bc (diff)
downloadlinux-5bfce5ef55cbe78ee2ee6e97f2e26a8a582008f3.tar.xz
x86, kaslr: Provide randomness functions
Adds potential sources of randomness: RDRAND, RDTSC, or the i8254. This moves the pre-alternatives inline rdrand function into the header so both pieces of code can use it. Availability of RDRAND is then controlled by CONFIG_ARCH_RANDOM, if someone wants to disable it even for kASLR. Signed-off-by: Kees Cook <keescook@chromium.org> Link: http://lkml.kernel.org/r/1381450698-28710-4-git-send-email-keescook@chromium.org Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/include/asm/archrandom.h')
-rw-r--r--arch/x86/include/asm/archrandom.h21
1 files changed, 21 insertions, 0 deletions
diff --git a/arch/x86/include/asm/archrandom.h b/arch/x86/include/asm/archrandom.h
index 0d9ec770f2f8..e6a92455740e 100644
--- 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);