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" <tytso@mit.edu>
Cc: stable@vger.kernel.org
diff --git a/drivers/char/random.c b/drivers/char/random.c
index df3358a..f67ae3e 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -254,6 +254,7 @@
#include <linux/cryptohash.h>
#include <linux/fips.h>
#include <linux/ptrace.h>
+#include <linux/kmemcheck.h>
#ifdef CONFIG_GENERIC_HARDIRQS
# include <linux/irq.h>
@@ -702,11 +703,7 @@
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 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 @@
/* 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);
}
/*