76 lines
2.6 KiB
Diff
76 lines
2.6 KiB
Diff
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Fri, 12 May 2017 15:46:17 +0200
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Subject: [PATCH] random: avoid preempt_disable()ed section
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.1-rt3.tar.xz
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extract_crng() will use sleeping locks while in a preempt_disable()
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section due to get_cpu_var().
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Work around it with local_locks.
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Cc: stable-rt@vger.kernel.org # where it applies to
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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drivers/char/random.c | 11 +++++++----
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1 file changed, 7 insertions(+), 4 deletions(-)
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--- a/drivers/char/random.c
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+++ b/drivers/char/random.c
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@@ -265,6 +265,7 @@
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#include <linux/syscalls.h>
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#include <linux/completion.h>
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#include <linux/uuid.h>
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+#include <linux/locallock.h>
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#include <crypto/chacha20.h>
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#include <asm/processor.h>
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@@ -2223,6 +2224,7 @@ static rwlock_t batched_entropy_reset_lo
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* at any point prior.
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*/
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static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64);
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+static DEFINE_LOCAL_IRQ_LOCK(batched_entropy_u64_lock);
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u64 get_random_u64(void)
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{
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u64 ret;
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@@ -2243,7 +2245,7 @@ u64 get_random_u64(void)
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warn_unseeded_randomness(&previous);
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use_lock = READ_ONCE(crng_init) < 2;
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- batch = &get_cpu_var(batched_entropy_u64);
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+ batch = &get_locked_var(batched_entropy_u64_lock, batched_entropy_u64);
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if (use_lock)
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read_lock_irqsave(&batched_entropy_reset_lock, flags);
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if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) {
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@@ -2253,12 +2255,13 @@ u64 get_random_u64(void)
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ret = batch->entropy_u64[batch->position++];
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if (use_lock)
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read_unlock_irqrestore(&batched_entropy_reset_lock, flags);
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- put_cpu_var(batched_entropy_u64);
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+ put_locked_var(batched_entropy_u64_lock, batched_entropy_u64);
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return ret;
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}
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EXPORT_SYMBOL(get_random_u64);
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static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32);
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+static DEFINE_LOCAL_IRQ_LOCK(batched_entropy_u32_lock);
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u32 get_random_u32(void)
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{
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u32 ret;
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@@ -2273,7 +2276,7 @@ u32 get_random_u32(void)
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warn_unseeded_randomness(&previous);
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use_lock = READ_ONCE(crng_init) < 2;
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- batch = &get_cpu_var(batched_entropy_u32);
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+ batch = &get_locked_var(batched_entropy_u32_lock, batched_entropy_u32);
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if (use_lock)
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read_lock_irqsave(&batched_entropy_reset_lock, flags);
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if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) {
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@@ -2283,7 +2286,7 @@ u32 get_random_u32(void)
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ret = batch->entropy_u32[batch->position++];
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if (use_lock)
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read_unlock_irqrestore(&batched_entropy_reset_lock, flags);
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- put_cpu_var(batched_entropy_u32);
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+ put_locked_var(batched_entropy_u32_lock, batched_entropy_u32);
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return ret;
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}
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EXPORT_SYMBOL(get_random_u32);
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