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drivers/entropy: stm32: fix inter-core race condition

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On STM32WB and dual-core STM32H7 MCUs, the RNG peripheral is shared
between the cores and its access is protected by a hardware semaphore.
Locking was not performed in the current entropy driver, leading to a
race condition when multiple cores concurrently used the RNG. This
commit implements the necessary logic for locking the HSEM during entropy
generation on multi-core STM32 MCUs. It also reconfigures the RNG in case
the configuration was changed by the other core, as this can happen e.g
on STM32WB MCUs.

Signed-off-by: Thomas Altenbach <taltenbach@witekio.com>
This commit is contained in:
Thomas Altenbach 2022-04-16 03:48:23 +02:00 • committed by Maureen Helm
commit cc51031445
2 changed files with 210 additions and 80 deletions
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32
soc/arm/st_stm32/common/stm32_hsem.h
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@ -129,6 +129,22 @@ static inline void z_stm32_hsem_lock(uint32_t hsem, uint32_t retry)
#endif /* CONFIG_SOC_SERIES_STM32WBX || CONFIG_STM32H7_DUAL_CORE || ... */
}
/**
* @brief Try to lock Hardware Semaphore
*/
static inline int z_stm32_hsem_try_lock(uint32_t hsem)
{
#if defined(CONFIG_SOC_SERIES_STM32WBX) || defined(CONFIG_STM32H7_DUAL_CORE) \
|| defined(CONFIG_SOC_SERIES_STM32MP1X)
if (LL_HSEM_1StepLock(HSEM, hsem)) {
return -EAGAIN;
}
#endif /* CONFIG_SOC_SERIES_STM32WBX || CONFIG_STM32H7_DUAL_CORE || ... */
return 0;
}
/**
* @brief Release Hardware Semaphore
*/
@ -140,4 +156,20 @@ static inline void z_stm32_hsem_unlock(uint32_t hsem)
#endif /* CONFIG_SOC_SERIES_STM32WBX || CONFIG_STM32H7_DUAL_CORE || ... */
}
/**
* @brief Indicates whether Hardware Semaphore is owned by this core
*/
static inline bool z_stm32_hsem_is_owned(uint32_t hsem)
{
bool owned = false;
#if defined(CONFIG_SOC_SERIES_STM32WBX) || defined(CONFIG_STM32H7_DUAL_CORE) \
|| defined(CONFIG_SOC_SERIES_STM32MP1X)
owned = LL_HSEM_GetCoreId(HSEM, hsem) == LL_HSEM_COREID;
#endif /* CONFIG_SOC_SERIES_STM32WBX || CONFIG_STM32H7_DUAL_CORE || ... */
return owned;
}
#endif /* ZEPHYR_INCLUDE_DRIVERS_HSEM_STM32_HSEM_H_ */