Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random

Pull /dev/random changes from Ted Ts'o:
 "A number of cleanups plus support for the RDSEED instruction, which
  will be showing up in Intel Broadwell CPU's"

* tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
  random: Add arch_has_random[_seed]()
  random: If we have arch_get_random_seed*(), try it before blocking
  random: Use arch_get_random_seed*() at init time and once a second
  x86, random: Enable the RDSEED instruction
  random: use the architectural HWRNG for the SHA's IV in extract_buf()
  random: clarify bits/bytes in wakeup thresholds
  random: entropy_bytes is actually bits
  random: simplify accounting code
  random: tighten bound on random_read_wakeup_thresh
  random: forget lock in lockless accounting
  random: simplify accounting logic
  random: fix comment on "account"
  random: simplify loop in random_read
  random: fix description of get_random_bytes
  random: fix comment on proc_do_uuid
  random: fix typos / spelling errors in comments

1 files changed, 41 insertions, 1 deletions

diff --git a/arch/x86/include/asm/archrandom.h b/arch/x86/include/asm/archrandom.h
index e6a9245..69f1366 100644
--- a/arch/x86/include/asm/archrandom.h
+++ b/arch/x86/include/asm/archrandom.h
@@ -1,7 +1,7 @@
 /*
  * This file is part of the Linux kernel.
  *
- * Copyright (c) 2011, Intel Corporation
+ * Copyright (c) 2011-2014, Intel Corporation
  * Authors: Fenghua Yu <fenghua.yu@intel.com>,
  *          H. Peter Anvin <hpa@linux.intel.com>
  *
@@ -31,10 +31,13 @@
 #define RDRAND_RETRY_LOOPS	10
 
 #define RDRAND_INT	".byte 0x0f,0xc7,0xf0"
+#define RDSEED_INT	".byte 0x0f,0xc7,0xf8"
 #ifdef CONFIG_X86_64
 # define RDRAND_LONG	".byte 0x48,0x0f,0xc7,0xf0"
+# define RDSEED_LONG	".byte 0x48,0x0f,0xc7,0xf8"
 #else
 # define RDRAND_LONG	RDRAND_INT
+# define RDSEED_LONG	RDSEED_INT
 #endif
 
 #ifdef CONFIG_ARCH_RANDOM
@@ -53,6 +56,16 @@ static inline int rdrand_long(unsigned long *v)
 	return ok;
 }
 
+/* A single attempt at RDSEED */
+static inline bool rdseed_long(unsigned long *v)
+{
+	unsigned char ok;
+	asm volatile(RDSEED_LONG "\n\t"
+		     "setc %0"
+		     : "=qm" (ok), "=a" (*v));
+	return ok;
+}
+
 #define GET_RANDOM(name, type, rdrand, nop)			\
 static inline int name(type *v)					\
 {								\
@@ -70,18 +83,40 @@ static inline int name(type *v)					\
 	return ok;						\
 }
 
+#define GET_SEED(name, type, rdseed, nop)			\
+static inline int name(type *v)					\
+{								\
+	unsigned char ok;					\
+	alternative_io("movb $0, %0\n\t"			\
+		       nop,					\
+		       rdseed "\n\t"				\
+		       "setc %0",				\
+		       X86_FEATURE_RDSEED,                      \
+		       ASM_OUTPUT2("=q" (ok), "=a" (*v)));	\
+	return ok;						\
+}
+
 #ifdef CONFIG_X86_64
 
 GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP5);
 GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP4);
 
+GET_SEED(arch_get_random_seed_long, unsigned long, RDSEED_LONG, ASM_NOP5);
+GET_SEED(arch_get_random_seed_int, unsigned int, RDSEED_INT, ASM_NOP4);
+
 #else
 
 GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP3);
 GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP3);
 
+GET_SEED(arch_get_random_seed_long, unsigned long, RDSEED_LONG, ASM_NOP4);
+GET_SEED(arch_get_random_seed_int, unsigned int, RDSEED_INT, ASM_NOP4);
+
 #endif /* CONFIG_X86_64 */
 
+#define arch_has_random()	static_cpu_has(X86_FEATURE_RDRAND)
+#define arch_has_random_seed()	static_cpu_has(X86_FEATURE_RDSEED)
+
 #else
 
 static inline int rdrand_long(unsigned long *v)
@@ -89,6 +124,11 @@ static inline int rdrand_long(unsigned long *v)
 	return 0;
 }
 
+static inline bool rdseed_long(unsigned long *v)
+{
+	return 0;
+}
+
 #endif  /* CONFIG_ARCH_RANDOM */
 
 extern void x86_init_rdrand(struct cpuinfo_x86 *c);