09ce2e218f
If there is a build setup problem where a device driver has not been setup for the entropy driver then the call to device_get_binding() will return a NULL value and the code will continue to use this NULL value. The result is a hard fault later in code execution. Note that CONFIG_ASSERT is by default off so one has to turn this configuration on to catch this problem. Signed-off-by: David Leach <david.leach@nxp.com>
45 lines
1.1 KiB
C
45 lines
1.1 KiB
C
/*
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* Copyright (c) 2017 Intel Corporation
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <atomic.h>
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#include <kernel.h>
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#include <entropy.h>
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static atomic_t entropy_driver;
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u32_t sys_rand32_get(void)
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{
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struct device *dev = (struct device *)atomic_get(&entropy_driver);
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u32_t random_num;
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int ret;
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if (unlikely(!dev)) {
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/* Only one entropy device exists, so this is safe even
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* if the whole operation isn't atomic.
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*/
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dev = device_get_binding(CONFIG_ENTROPY_NAME);
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__ASSERT((dev != NULL),
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"Device driver for %s (CONFIG_ENTROPY_NAME) not found. "
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"Check your build configuration!",
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CONFIG_ENTROPY_NAME);
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atomic_set(&entropy_driver, (atomic_t)(uintptr_t)dev);
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}
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ret = entropy_get_entropy(dev, (u8_t *)&random_num,
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sizeof(random_num));
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if (unlikely(ret < 0)) {
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/* Use system timer in case the entropy device couldn't deliver
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* 32-bit of data. There's not much that can be done in this
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* situation. An __ASSERT() isn't used here as the HWRNG might
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* still be gathering entropy during early boot situations.
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*/
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random_num = k_cycle_get_32();
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}
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return random_num;
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}
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