From b83e45fd065c3cfdb8cc0179bbddf296ce4d4fda Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Wed, 30 Nov 2022 03:14:15 +0100 Subject: random: mix in cycle counter when jitter timer fires Rather than just relying on interaction between cache lines of the timer and the main loop, also explicitly take into account the fact that the timer might fire at some time that's hard to predict, due to scheduling, interrupts, or cross-CPU conditions. Mix in a cycle counter during the firing of the timer, in addition to the existing one during the scheduling of the timer. It can't hurt and can only help. Signed-off-by: Jason A. Donenfeld --- drivers/char/random.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/char/random.c') diff --git a/drivers/char/random.c b/drivers/char/random.c index 3db4bf6f9b43..36d29da31af0 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1251,7 +1251,9 @@ struct entropy_timer_state { static void __cold entropy_timer(struct timer_list *timer) { struct entropy_timer_state *state = container_of(timer, struct entropy_timer_state, timer); + unsigned long entropy = random_get_entropy(); + mix_pool_bytes(&entropy, sizeof(entropy)); if (atomic_inc_return(&state->samples) % state->samples_per_bit == 0) credit_init_bits(1); } -- cgit