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authorTheodore Ts'o <tytso@mit.edu>2013-09-21 21:58:22 +0400
committerTheodore Ts'o <tytso@mit.edu>2013-10-10 22:30:53 +0400
commit61875f30daf60305712e25b209ef41ced2635bad (patch)
tree176cda3ae729c520bff1b0f6a19806c18c0a7523 /drivers
parent47d06e532e95b71c0db3839ebdef3fe8812fca2c (diff)
downloadlinux-61875f30daf60305712e25b209ef41ced2635bad.tar.xz
random: allow architectures to optionally define random_get_entropy()
Allow architectures which have a disabled get_cycles() function to provide a random_get_entropy() function which provides a fine-grained, rapidly changing counter that can be used by the /dev/random driver. For example, an architecture might have a rapidly changing register used to control random TLB cache eviction, or DRAM refresh that doesn't meet the requirements of get_cycles(), but which is good enough for the needs of the random driver. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@vger.kernel.org
Diffstat (limited to 'drivers')
-rw-r--r--drivers/char/random.c8
1 files changed, 4 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);