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* random: Add arch_has_random[_seed]()H. Peter Anvin2014-03-191-0/+9
| | | | | | | | | | | | 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>
* x86, random: Enable the RDSEED instructionH. Peter Anvin2014-03-191-0/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | Upcoming Intel silicon adds a new RDSEED instruction, which is similar to RDRAND but provides a stronger guarantee: unlike RDRAND, RDSEED will always reseed the PRNG from the true random number source between each read. Thus, the output of RDSEED is guaranteed to be 100% entropic, unlike RDRAND which is only architecturally guaranteed to be 1/512 entropic (although in practice is much more.) The RDSEED instruction takes the same time to execute as RDRAND, but RDSEED unlike RDRAND can legitimately return failure (CF=0) due to entropy exhaustion if too many threads on too many cores are hammering the RDSEED instruction at the same time. Therefore, we have to be more conservative and only use it in places where we can tolerate failures. This patch introduces the primitives arch_get_random_seed_{int,long}() but does not use it yet. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Reviewed-by: Ingo Molnar <mingo@kernel.org> 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>
* powerpc: Implement arch_get_random_long/int() for powernvMichael Ellerman2013-10-111-0/+32
Add the plumbing to implement arch_get_random_long/int(). It didn't seem worth adding an extra ppc_md hook for int, so we reuse the one for long. Add an implementation for powernv based on the hwrng found in power7+ systems. We whiten the output of the hwrng, and the result passes all the dieharder tests. Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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