forked from Minki/linux
01c9348c76
The hardware RNG on POWER8 and POWER7+ can be relatively slow, since
it can only supply one 64-bit value per microsecond. Currently we
read it in arch_get_random_long(), but that slows down reading from
/dev/urandom since the code in random.c calls arch_get_random_long()
for every longword read from /dev/urandom.
Since the hardware RNG supplies high-quality entropy on every read, it
matches the semantics of arch_get_random_seed_long() better than those
of arch_get_random_long(). Therefore this commit makes the code use
the POWER8/7+ hardware RNG only for arch_get_random_seed_{long,int}
and not for arch_get_random_{long,int}.
This won't affect any other PowerPC-based platforms because none of
them currently support a hardware RNG. To make it clear that the
ppc_md function pointer is used for arch_get_random_seed_*, we rename
it from get_random_long to get_random_seed.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
58 lines
1.1 KiB
C
58 lines
1.1 KiB
C
#ifndef _ASM_POWERPC_ARCHRANDOM_H
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#define _ASM_POWERPC_ARCHRANDOM_H
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#ifdef CONFIG_ARCH_RANDOM
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#include <asm/machdep.h>
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static inline int arch_get_random_long(unsigned long *v)
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{
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return 0;
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}
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static inline int arch_get_random_int(unsigned int *v)
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{
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return 0;
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}
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static inline int arch_get_random_seed_long(unsigned long *v)
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{
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if (ppc_md.get_random_seed)
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return ppc_md.get_random_seed(v);
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return 0;
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}
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static inline int arch_get_random_seed_int(unsigned int *v)
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{
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unsigned long val;
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int rc;
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rc = arch_get_random_long(&val);
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if (rc)
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*v = val;
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return rc;
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}
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static inline int arch_has_random(void)
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{
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return 0;
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}
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static inline int arch_has_random_seed(void)
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{
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return !!ppc_md.get_random_seed;
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}
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#endif /* CONFIG_ARCH_RANDOM */
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#ifdef CONFIG_PPC_POWERNV
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int powernv_hwrng_present(void);
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int powernv_get_random_long(unsigned long *v);
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int powernv_get_random_real_mode(unsigned long *v);
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#else
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static inline int powernv_hwrng_present(void) { return 0; }
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static inline int powernv_get_random_real_mode(unsigned long *v) { return 0; }
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#endif
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#endif /* _ASM_POWERPC_ARCHRANDOM_H */
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