diff options
| -rw-r--r-- | drivers/char/random.c | 8 | ||||
| -rw-r--r-- | include/linux/timex.h | 14 |
2 files changed, 18 insertions, 4 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index 92e6c67e1ae6..2d5daf9b58e9 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -643,7 +643,7 @@ struct timer_rand_state { */ void add_device_randomness(const void *buf, unsigned int size) { - unsigned long time = get_cycles() ^ jiffies; + unsigned long time = random_get_entropy() ^ jiffies; mix_pool_bytes(&input_pool, buf, size, NULL); mix_pool_bytes(&input_pool, &time, sizeof(time), NULL); @@ -680,7 +680,7 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num) goto out; sample.jiffies = jiffies; - sample.cycles = get_cycles(); + sample.cycles = random_get_entropy(); sample.num = num; mix_pool_bytes(&input_pool, &sample, sizeof(sample), NULL); @@ -747,7 +747,7 @@ void add_interrupt_randomness(int irq, int irq_flags) struct fast_pool *fast_pool = &__get_cpu_var(irq_randomness); struct pt_regs *regs = get_irq_regs(); unsigned long now = jiffies; - __u32 input[4], cycles = get_cycles(); + __u32 input[4], cycles = random_get_entropy(); input[0] = cycles ^ jiffies; input[1] = irq; @@ -1485,7 +1485,7 @@ unsigned int get_random_int(void) hash = get_cpu_var(get_random_int_hash); - hash[0] += current->pid + jiffies + get_cycles(); + hash[0] += current->pid + jiffies + random_get_entropy(); md5_transform(hash, random_int_secret); ret = hash[0]; put_cpu_var(get_random_int_hash); diff --git a/include/linux/timex.h b/include/linux/timex.h index b3726e61368e..da4c32dbb2aa 100644 --- a/include/linux/timex.h +++ b/include/linux/timex.h @@ -64,6 +64,20 @@ #include <asm/timex.h> +#ifndef random_get_entropy +/* + * The random_get_entropy() function is used by the /dev/random driver + * in order to extract entropy via the relative unpredictability of + * when an interrupt takes places versus a high speed, fine-grained + * timing source or cycle counter. Since it will be occurred on every + * single interrupt, it must have a very low cost/overhead. + * + * By default we use get_cycles() for this purpose, but individual + * architectures may override this in their asm/timex.h header file. + */ +#define random_get_entropy() get_cycles() +#endif + /* * SHIFT_PLL is used as a dampening factor to define how much we * adjust the frequency correction for a given offset in PLL mode. |