From e6d4947b12e8ad947add1032dd754803c6004824 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Thu, 5 Jul 2012 10:21:01 -0400 Subject: [PATCH] random: use the arch-specific rng in xfer_secondary_pool 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. Signed-off-by: "Theodore Ts'o" Cc: stable@vger.kernel.org --- drivers/char/random.c | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index df3358ab5b99..f67ae3e473ba 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -254,6 +254,7 @@ #include #include #include +#include #ifdef CONFIG_GENERIC_HARDIRQS # include @@ -702,11 +703,7 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num) goto out; sample.jiffies = jiffies; - - /* Use arch random value, fall back to cycles */ - if (!arch_get_random_int(&sample.cycles)) - sample.cycles = get_cycles(); - + sample.cycles = get_cycles(); sample.num = num; mix_pool_bytes(&input_pool, &sample, sizeof(sample), NULL); @@ -838,7 +835,11 @@ 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; if (r->pull && r->entropy_count < nbytes * 8 && r->entropy_count < r->poolinfo->POOLBITS) { @@ -849,17 +850,23 @@ static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes) /* pull at least as many as BYTES as wakeup BITS */ bytes = max_t(int, bytes, random_read_wakeup_thresh / 8); /* but never more than the buffer size */ - bytes = min_t(int, bytes, sizeof(tmp)); + bytes = min_t(int, bytes, sizeof(u.tmp)); DEBUG_ENT("going to reseed %s with %d bits " "(%d of %d requested)\n", r->name, bytes * 8, nbytes * 8, r->entropy_count); - bytes = extract_entropy(r->pull, tmp, bytes, + bytes = extract_entropy(r->pull, u.tmp, bytes, random_read_wakeup_thresh / 8, rsvd); - mix_pool_bytes(r, tmp, bytes, NULL); + mix_pool_bytes(r, u.tmp, bytes, NULL); credit_entropy_bits(r, bytes*8); } + kmemcheck_mark_initialized(&u.hwrand, sizeof(u.hwrand)); + 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); } /* -- 2.39.5