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83683ddd3d
When getting a stack protector canary value, check if cpu supports FEAT_RNG and use that. Fallback to old method of using a (hardcoded value ^ timer). Signed-off-by: Tomas Pilar <tomas@nuviainc.com> Change-Id: I8181acf8e31661d4cc82bc3a4078f8751909e725
32 lines
813 B
C
32 lines
813 B
C
/*
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* Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <stdint.h>
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#include <arch_helpers.h>
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#include <arch_features.h>
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#include <plat/common/platform.h>
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#define RANDOM_CANARY_VALUE ((u_register_t) 3288484550995823360ULL)
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u_register_t plat_get_stack_protector_canary(void)
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{
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#if ENABLE_FEAT_RNG
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/* Use the RNDR instruction if the CPU supports it */
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if (is_armv8_5_rng_present()) {
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return read_rndr();
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}
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#endif
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/*
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* Ideally, a random number should be returned above. If a random
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* number generator is not supported, return instead a
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* combination of a timer's value and a compile-time constant.
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* This is better than nothing but not necessarily really secure.
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*/
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return RANDOM_CANARY_VALUE ^ read_cntpct_el0();
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}
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