Re: [PATCH 07/12] random: use the arch-specific rng in xfer_secondary_pool
From: Ben Hutchings <hidden>
Date: 2012-07-08 01:07:05
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lkml
On Fri, 2012-07-06 at 18:44 -0400, Theodore Ts'o wrote:
If the CPU supports a hardware random number generator, use it in xfer_secondary_pool(), where it will significantly improve things and where we can afford it. Also, remove the use of the arch-specific rng in add_timer_randomness(), since the call is significantly slower than get_cycles(), and we're much better off using it in xfer_secondary_pool() anyway.
[...]
quoted hunk ↗ jump to hunk
@@ -838,7 +834,11 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf, */ static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes) { - __u32 tmp[OUTPUT_POOL_WORDS]; + union { + __u32 tmp[OUTPUT_POOL_WORDS]; + long hwrand[4]; + } u; + int i;
[...]
+ for (i = 0; i < 4; i++) + if (arch_get_random_long(&u.hwrand[i])) + break; + if (i) + mix_pool_bytes(r, &u.hwrand, sizeof(u.hwrand), 0);
[...] Surely the number of random bytes being added is i * sizeof(long), not sizeof(u.hwrand)? Ben. -- Ben Hutchings Life would be so much easier if we could look at the source code.
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