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random: Add arch_has_random[_seed]() 

Add predicate functions for having arch_get_random[_seed]*().  The
only current use is to avoid the loop in arch_random_refill() when
arch_get_random_seed_long() is unavailable.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
H. Peter Anvin 2014-03-17 16:36:30 -07:00 committed by Theodore Ts'o
parent 331c6490c7
commit 7b878d4b48
4 changed files with 23 additions and 0 deletions
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9
arch/powerpc/include/asm/archrandom.h
View File

@ -25,6 +25,11 @@ static inline int arch_get_random_int(unsigned int *v)
return rc; return rc;
} }
static inline int arch_has_random(void)
{
return !!ppc_md.get_random_long;
}
int powernv_get_random_long(unsigned long *v); int powernv_get_random_long(unsigned long *v);
static inline int arch_get_random_seed_long(unsigned long *v) static inline int arch_get_random_seed_long(unsigned long *v)
@ -35,6 +40,10 @@ static inline int arch_get_random_seed_int(unsigned int *v)
{ {
return 0; return 0;
} }
static inline int arch_has_random_seed(void)
{
return 0;
}
#endif /* CONFIG_ARCH_RANDOM */ #endif /* CONFIG_ARCH_RANDOM */

3
arch/x86/include/asm/archrandom.h
View File

@ -114,6 +114,9 @@ GET_SEED(arch_get_random_seed_int, unsigned int, RDSEED_INT, ASM_NOP4);
#endif /* CONFIG_X86_64 */ #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 #else
static inline int rdrand_long(unsigned long *v) static inline int rdrand_long(unsigned long *v)

3
drivers/char/random.c
View File

@ -1307,6 +1307,9 @@ static int arch_random_refill(void)
unsigned int i; unsigned int i;
unsigned long buf[nlongs]; unsigned long buf[nlongs];
if (!arch_has_random_seed())
return 0;
for (i = 0; i < nlongs; i++) { for (i = 0; i < nlongs; i++) {
if (arch_get_random_seed_long(&buf[n])) if (arch_get_random_seed_long(&buf[n]))
n++; n++;

8
include/linux/random.h
View File

@ -88,6 +88,10 @@ static inline int arch_get_random_int(unsigned int *v)
{ {
return 0; return 0;
} }
static inline int arch_has_random(void)
{
return 0;
}
static inline int arch_get_random_seed_long(unsigned long *v) static inline int arch_get_random_seed_long(unsigned long *v)
{ {
return 0; return 0;
@ -96,6 +100,10 @@ static inline int arch_get_random_seed_int(unsigned int *v)
{ {
return 0; return 0;
} }
static inline int arch_has_random_seed(void)
{
return 0;
}
#endif #endif
/* Pseudo random number generator from numerical recipes. */ /* Pseudo random number generator from numerical recipes. */