diff options
Diffstat (limited to 'drivers/char/random.c')
| -rw-r--r-- | drivers/char/random.c | 92 |
1 files changed, 68 insertions, 24 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index dfe918a..d3bb792 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -267,6 +267,8 @@ #define CREATE_TRACE_POINTS #include <trace/events/random.h> +/* #define ADD_INTERRUPT_BENCH */ + /* * Configuration information */ @@ -558,25 +560,29 @@ struct fast_pool { * collector. It's hardcoded for an 128 bit pool and assumes that any * locks that might be needed are taken by the caller. */ -static void fast_mix(struct fast_pool *f, __u32 input[4]) +static void fast_mix(struct fast_pool *f) { - __u32 w; - unsigned input_rotate = f->rotate; - - w = rol32(input[0], input_rotate) ^ f->pool[0] ^ f->pool[3]; - f->pool[0] = (w >> 3) ^ twist_table[w & 7]; - input_rotate = (input_rotate + 14) & 31; - w = rol32(input[1], input_rotate) ^ f->pool[1] ^ f->pool[0]; - f->pool[1] = (w >> 3) ^ twist_table[w & 7]; - input_rotate = (input_rotate + 7) & 31; - w = rol32(input[2], input_rotate) ^ f->pool[2] ^ f->pool[1]; - f->pool[2] = (w >> 3) ^ twist_table[w & 7]; - input_rotate = (input_rotate + 7) & 31; - w = rol32(input[3], input_rotate) ^ f->pool[3] ^ f->pool[2]; - f->pool[3] = (w >> 3) ^ twist_table[w & 7]; - input_rotate = (input_rotate + 7) & 31; - - f->rotate = input_rotate; + __u32 a = f->pool[0], b = f->pool[1]; + __u32 c = f->pool[2], d = f->pool[3]; + + a += b; c += d; + b = rol32(a, 6); d = rol32(c, 27); + d ^= a; b ^= c; + + a += b; c += d; + b = rol32(a, 16); d = rol32(c, 14); + d ^= a; b ^= c; + + a += b; c += d; + b = rol32(a, 6); d = rol32(c, 27); + d ^= a; b ^= c; + + a += b; c += d; + b = rol32(a, 16); d = rol32(c, 14); + d ^= a; b ^= c; + + f->pool[0] = a; f->pool[1] = b; + f->pool[2] = c; f->pool[3] = d; f->count++; } @@ -829,6 +835,27 @@ EXPORT_SYMBOL_GPL(add_input_randomness); static DEFINE_PER_CPU(struct fast_pool, irq_randomness); +#ifdef ADD_INTERRUPT_BENCH +static unsigned long avg_cycles, avg_deviation; + +#define AVG_SHIFT 8 /* Exponential average factor k=1/256 */ +#define FIXED_1_2 (1 << (AVG_SHIFT-1)) + +static void add_interrupt_bench(cycles_t start) +{ + long delta = random_get_entropy() - start; + + /* Use a weighted moving average */ + delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT); + avg_cycles += delta; + /* And average deviation */ + delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT); + avg_deviation += delta; +} +#else +#define add_interrupt_bench(x) +#endif + void add_interrupt_randomness(int irq, int irq_flags) { struct entropy_store *r; @@ -836,22 +863,23 @@ void add_interrupt_randomness(int irq, int irq_flags) struct pt_regs *regs = get_irq_regs(); unsigned long now = jiffies; cycles_t cycles = random_get_entropy(); - __u32 input[4], c_high, j_high; + __u32 c_high, j_high; __u64 ip; unsigned long seed; int credit = 0; c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0; j_high = (sizeof(now) > 4) ? now >> 32 : 0; - input[0] = cycles ^ j_high ^ irq; - input[1] = now ^ c_high; + fast_pool->pool[0] ^= cycles ^ j_high ^ irq; + fast_pool->pool[1] ^= now ^ c_high; ip = regs ? instruction_pointer(regs) : _RET_IP_; - input[2] = ip; - input[3] = ip >> 32; + fast_pool->pool[2] ^= ip; + fast_pool->pool[3] ^= ip >> 32; - fast_mix(fast_pool, input); + fast_mix(fast_pool); if ((irq_flags & __IRQF_TIMER) == 0) fast_pool->notimer_count++; + add_interrupt_bench(cycles); if (cycles) { if ((fast_pool->count < 64) && @@ -1650,6 +1678,22 @@ struct ctl_table random_table[] = { .mode = 0444, .proc_handler = proc_do_uuid, }, +#ifdef ADD_INTERRUPT_BENCH + { + .procname = "add_interrupt_avg_cycles", + .data = &avg_cycles, + .maxlen = sizeof(avg_cycles), + .mode = 0444, + .proc_handler = proc_doulongvec_minmax, + }, + { + .procname = "add_interrupt_avg_deviation", + .data = &avg_deviation, + .maxlen = sizeof(avg_deviation), + .mode = 0444, + .proc_handler = proc_doulongvec_minmax, + }, +#endif { } }; #endif /* CONFIG_SYSCTL */ |
