Some upcoming changes will introduce additional callers of them.
Signed-off-by: Thomas Weißschuh <thomas.weisssc...@linutronix.de>
---
drivers/char/random.c | 51 +++++++++++++++++++++++++++++++++------------------
1 file changed, 33 insertions(+), 18 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index
b0b88c6f6a1afcdb770e39b7a64cb3408e33bd2c..73c53a4fb949bfd2ed723fa3cec3fe0d066a7fa3
100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -246,6 +246,37 @@ static unsigned int crng_reseed_interval(void)
/* Used by crng_reseed() and crng_make_state() to extract a new seed from the
input pool. */
static void extract_entropy(void *buf, size_t len);
+/* This updates the generation in the vDSO data page */
+static void random_vdso_update_generation(unsigned long next_gen)
+{
+ if (!IS_ENABLED(CONFIG_VDSO_GETRANDOM))
+ 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
+ * is ordered with the write above to base_crng.generation. Pairs with
+ * the smp_rmb() before the syscall in the vDSO code.
+ *
+ * Cast to unsigned long for 32-bit architectures, since atomic 64-bit
+ * operations are not supported on those architectures. This is safe
+ * because base_crng.generation is a 32-bit value. On big-endian
+ * architectures it will be stored in the upper 32 bits, but that's okay
+ * because the vDSO side only checks whether the value changed, without
+ * actually using or interpreting the value.
+ */
+ smp_store_release((unsigned long *)&vdso_k_rng_data->generation,
next_gen + 1);
+}
+
+/* This sets is_ready in the vDSO data page */
+static void random_vdso_set_ready(void)
+{
+ if (!IS_ENABLED(CONFIG_VDSO_GETRANDOM))
+ return;
+
+ WRITE_ONCE(vdso_k_rng_data->is_ready, true);
+}
+
/* This extracts a new crng key from the input pool. */
static void crng_reseed(struct work_struct *work)
{
@@ -272,22 +303,7 @@ static void crng_reseed(struct work_struct *work)
if (next_gen == ULONG_MAX)
++next_gen;
WRITE_ONCE(base_crng.generation, next_gen);
-
- /* 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
- * is ordered with the write above to base_crng.generation. Pairs with
- * the smp_rmb() before the syscall in the vDSO code.
- *
- * Cast to unsigned long for 32-bit architectures, since atomic 64-bit
- * operations are not supported on those architectures. This is safe
- * because base_crng.generation is a 32-bit value. On big-endian
- * architectures it will be stored in the upper 32 bits, but that's okay
- * because the vDSO side only checks whether the value changed, without
- * actually using or interpreting the value.
- */
- if (IS_ENABLED(CONFIG_VDSO_GETRANDOM))
- smp_store_release((unsigned long
*)&vdso_k_rng_data->generation, next_gen + 1);
+ random_vdso_update_generation(next_gen);
if (!static_branch_likely(&crng_is_ready))
crng_init = CRNG_READY;
@@ -741,8 +757,7 @@ static void __cold _credit_init_bits(size_t bits)
if (static_key_initialized && system_unbound_wq)
queue_work(system_unbound_wq, &set_ready);
atomic_notifier_call_chain(&random_ready_notifier, 0, NULL);
- if (IS_ENABLED(CONFIG_VDSO_GETRANDOM))
- WRITE_ONCE(vdso_k_rng_data->is_ready, true);
+ random_vdso_set_ready();
wake_up_interruptible(&crng_init_wait);
kill_fasync(&fasync, SIGIO, POLL_IN);
pr_notice("crng init done\n");
--
2.51.0
