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kernel: Use IS-specific entropy function when available

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During the early boot process, in prepare_multithreading(), the kernel
structures and scheduler are not ready yet. In order to obtain entropy
for early works such as stack randomization, optionally use when present
the ISR-specific function that some drivers will provide.

Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
This commit is contained in:
Carles Cufi 2018-05-24 20:12:23 +02:00 • committed by Andrew Boie
commit b54644913d
1 changed files with 13 additions and 6 deletions
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19
kernel/init.c
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@ -389,15 +389,22 @@ u32_t z_early_boot_rand32_get(void)
goto sys_rand32_fallback;
}
rc = entropy_get_entropy(entropy, (u8_t *)&retval, sizeof(retval));
if (rc == 0) {
/* Try to see if driver provides an ISR-specific API */
rc = entropy_get_entropy_isr(entropy, (u8_t *)&retval,
sizeof(retval), ENTROPY_BUSYWAIT);
if (rc == -ENOTSUP) {
/* Driver does not provide an ISR-specific API, assume it can
* be called from ISR context
*/
rc = entropy_get_entropy(entropy, (u8_t *)&retval,
sizeof(retval));
}
if (rc >= 0) {
return retval;
}
/* FIXME: rc could be -EAGAIN here, for cases where the entropy
* driver doesn't yet have the requested amount of entropy. In
* the meantime, just use the fallback with sys_rand32_get().
*/
/* Fall through to fallback */
sys_rand32_fallback:
#endif