diff options
| -rw-r--r-- | drivers/char/random.c | 51 | ||||
| -rw-r--r-- | include/linux/prefetch.h | 12 |
2 files changed, 47 insertions, 16 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index 117f195029a1..6941fdeb6a4b 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -490,12 +490,15 @@ static inline __u32 int_ln_12bits(__u32 word) **********************************************************************/ struct entropy_store { + /* mostly-read data: */ + struct poolinfo poolinfo; + __u32 *pool; + + /* read-write data: */ + spinlock_t lock ____cacheline_aligned_in_smp; unsigned add_ptr; int entropy_count; int input_rotate; - struct poolinfo poolinfo; - __u32 *pool; - spinlock_t lock; }; /* @@ -571,38 +574,54 @@ static void add_entropy_words(struct entropy_store *r, const __u32 *in, static __u32 const twist_table[8] = { 0, 0x3b6e20c8, 0x76dc4190, 0x4db26158, 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 }; - unsigned i; - int new_rotate; + unsigned long i, add_ptr, tap1, tap2, tap3, tap4, tap5; + int new_rotate, input_rotate; int wordmask = r->poolinfo.poolwords - 1; - __u32 w; + __u32 w, next_w; unsigned long flags; + /* Taps are constant, so we can load them without holding r->lock. */ + tap1 = r->poolinfo.tap1; + tap2 = r->poolinfo.tap2; + tap3 = r->poolinfo.tap3; + tap4 = r->poolinfo.tap4; + tap5 = r->poolinfo.tap5; + next_w = *in++; + spin_lock_irqsave(&r->lock, flags); + prefetch_range(r->pool, wordmask); + input_rotate = r->input_rotate; + add_ptr = r->add_ptr; while (nwords--) { - w = rotate_left(r->input_rotate, *in++); - i = r->add_ptr = (r->add_ptr - 1) & wordmask; + w = rotate_left(input_rotate, next_w); + if (nwords > 0) + next_w = *in++; + i = add_ptr = (add_ptr - 1) & wordmask; /* * Normally, we add 7 bits of rotation to the pool. * At the beginning of the pool, add an extra 7 bits * rotation, so that successive passes spread the * input bits across the pool evenly. */ - new_rotate = r->input_rotate + 14; + new_rotate = input_rotate + 14; if (i) - new_rotate = r->input_rotate + 7; - r->input_rotate = new_rotate & 31; + new_rotate = input_rotate + 7; + input_rotate = new_rotate & 31; /* XOR in the various taps */ - w ^= r->pool[(i + r->poolinfo.tap1) & wordmask]; - w ^= r->pool[(i + r->poolinfo.tap2) & wordmask]; - w ^= r->pool[(i + r->poolinfo.tap3) & wordmask]; - w ^= r->pool[(i + r->poolinfo.tap4) & wordmask]; - w ^= r->pool[(i + r->poolinfo.tap5) & wordmask]; + w ^= r->pool[(i + tap1) & wordmask]; + w ^= r->pool[(i + tap2) & wordmask]; + w ^= r->pool[(i + tap3) & wordmask]; + w ^= r->pool[(i + tap4) & wordmask]; + w ^= r->pool[(i + tap5) & wordmask]; w ^= r->pool[i]; r->pool[i] = (w >> 3) ^ twist_table[w & 7]; } + r->input_rotate = input_rotate; + r->add_ptr = add_ptr; + spin_unlock_irqrestore(&r->lock, flags); } diff --git a/include/linux/prefetch.h b/include/linux/prefetch.h index 73c4a344156b..fc86f274147f 100644 --- a/include/linux/prefetch.h +++ b/include/linux/prefetch.h @@ -10,6 +10,7 @@ #ifndef _LINUX_PREFETCH_H #define _LINUX_PREFETCH_H +#include <linux/types.h> #include <asm/processor.h> #include <asm/cache.h> @@ -54,4 +55,15 @@ static inline void prefetchw(const void *x) {;} #define PREFETCH_STRIDE (4*L1_CACHE_BYTES) #endif +static inline void prefetch_range(void *addr, size_t len) +{ +#ifdef ARCH_HAS_PREFETCH + char *cp; + char *end = addr + len; + + for (cp = addr; cp < end; cp += PREFETCH_STRIDE) + prefetch(cp); +#endif +} + #endif |