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random: remove ifdef'd out interrupt bench 

commit 95e6060c20 upstream.

With tools like kbench9000 giving more finegrained responses, and this
basically never having been used ever since it was initially added,
let's just get rid of this. There *is* still work to be done on the
interrupt handler, but this really isn't the way it's being developed.

Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jason A. Donenfeld 2022-02-10 16:35:24 +01:00 committed by Greg Kroah-Hartman
parent d52d9b75cf
commit 5dde7c4d00
2 changed files with 0 additions and 49 deletions
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9
Documentation/admin-guide/sysctl/kernel.rst
View File

@ -1042,15 +1042,6 @@ This is a directory, with the following entries:
are woken up. This file is writable for compatibility purposes, but
writing to it has no effect on any RNG behavior.
If ``drivers/char/random.c`` is built with ``ADD_INTERRUPT_BENCH``
defined, these additional entries are present:
* ``add_interrupt_avg_cycles``: the average number of cycles between
interrupts used to feed the pool;
* ``add_interrupt_avg_deviation``: the standard deviation seen on the
number of cycles between interrupts used to feed the pool.
randomize_va_space
==================

40
drivers/char/random.c
View File

@ -240,8 +240,6 @@
#define CREATE_TRACE_POINTS
#include <trace/events/random.h>
/* #define ADD_INTERRUPT_BENCH */
enum {
POOL_BITS = BLAKE2S_HASH_SIZE * 8,
POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */
@ -808,27 +806,6 @@ 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
static u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
{
u32 *ptr = (u32 *)regs;
@ -865,7 +842,6 @@ void add_interrupt_randomness(int irq)
(sizeof(ip) > 4) ? ip >> 32 : get_reg(fast_pool, regs);
fast_mix(fast_pool);
add_interrupt_bench(cycles);
if (unlikely(crng_init == 0)) {
if (fast_pool->count >= 64 &&
@ -1574,22 +1550,6 @@ static 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
{ }
};