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| author | Theodore Ts'o <tytso@mit.edu> | 2012-07-05 10:21:01 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2012-07-14 20:17:46 -0400 |
| commit | e6d4947b12e8ad947add1032dd754803c6004824 (patch) | |
| tree | cfbfba88cf3dc1ffb01634a6eed68a220d4a13c7 /drivers/char/random.c | |
| parent | 7bf2357524408b97fec58344caf7397f8140c3fd (diff) | |
| download | lwn-e6d4947b12e8ad947add1032dd754803c6004824.tar.gz lwn-e6d4947b12e8ad947add1032dd754803c6004824.zip | |
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
Diffstat (limited to 'drivers/char/random.c')
| -rw-r--r-- | drivers/char/random.c | 25 |
1 files 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 <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 @@ 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); } /* |