linux-kernel - [PATCH 1/3] random: remove ifdef'd out interrupt bench

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20220210155012.136485-2-Jason@zx2c4.com>
Date:   Thu, 10 Feb 2022 16:50:10 +0100
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     linux-kernel@...r.kernel.org
Cc:     "Jason A. Donenfeld" <Jason@...c4.com>,
        Theodore Ts'o <tytso@....edu>,
        Dominik Brodowski <linux@...inikbrodowski.net>
Subject: [PATCH 1/3] random: remove ifdef'd out interrupt bench

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@....edu>
Cc: Dominik Brodowski <linux@...inikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
---
 drivers/char/random.c | 40 ----------------------------------------
 1 file changed, 40 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 57d36f13e3a6..cf535596d1bc 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -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. */
@@ -806,27 +804,6 @@ 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;
@@ -885,7 +862,6 @@ void add_interrupt_randomness(int irq)
 		(sizeof(ip) > 4) ? ip >> 32 : get_reg(fast_pool, regs);
 
 	fast_mix(fast_pool);
-	add_interrupt_bench(cycles);
 	new_count = ++fast_pool->count;
 
 	if (unlikely(crng_init == 0)) {
@@ -1595,22 +1571,6 @@ 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
 	{ }
 };
 
-- 
2.35.0