Upcoming changes to the generic vDSO library will mean that the vDSO datapage will not yet be usable during early boot.
Introduce a static key which prevents early accesses.
Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de Tested-by: Andreas Larsson andreas@gaisler.com Reviewed-by: Andreas Larsson andreas@gaisler.com --- drivers/char/random.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c index 73c53a4fb949bfd2ed723fa3cec3fe0d066a7fa3..f39524fb076a0c77bab228d4f2d45fee37291eb0 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -88,6 +88,7 @@ static DEFINE_STATIC_KEY_FALSE(crng_is_ready); static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); static struct fasync_struct *fasync; static ATOMIC_NOTIFIER_HEAD(random_ready_notifier); +static DEFINE_STATIC_KEY_FALSE(random_vdso_is_ready);
/* Control how we warn userspace. */ static struct ratelimit_state urandom_warning = @@ -252,6 +253,9 @@ static void random_vdso_update_generation(unsigned long next_gen) if (!IS_ENABLED(CONFIG_VDSO_GETRANDOM)) return;
+ if (!static_branch_likely(&random_vdso_is_ready)) + return; + /* base_crng.generation's invalid value is ULONG_MAX, while * vdso_k_rng_data->generation's invalid value is 0, so add one to the * former to arrive at the latter. Use smp_store_release so that this @@ -274,6 +278,9 @@ static void random_vdso_set_ready(void) if (!IS_ENABLED(CONFIG_VDSO_GETRANDOM)) return;
+ if (!static_branch_likely(&random_vdso_is_ready)) + return; + WRITE_ONCE(vdso_k_rng_data->is_ready, true); }
@@ -925,6 +932,9 @@ void __init random_init(void) _mix_pool_bytes(&entropy, sizeof(entropy)); add_latent_entropy();
+ if (IS_ENABLED(CONFIG_VDSO_GETRANDOM)) + static_branch_enable(&random_vdso_is_ready); + /* * If we were initialized by the cpu or bootloader before jump labels * or workqueues are initialized, then we should enable the static @@ -934,8 +944,10 @@ void __init random_init(void) crng_set_ready(NULL);
/* Reseed if already seeded by earlier phases. */ - if (crng_ready()) + if (crng_ready()) { crng_reseed(NULL); + random_vdso_set_ready(); + }
WARN_ON(register_pm_notifier(&pm_notifier));