36 lines
911 B
C
36 lines
911 B
C
/*
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* Copyright (c) 2020, 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 <plat/common/platform.h>
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static uint32_t plat_generate_random_number(void)
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{
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uintptr_t return_addr = (uintptr_t)__builtin_return_address(0U);
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uintptr_t frame_addr = (uintptr_t)__builtin_frame_address(0U);
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uint64_t cntpct = read_cntpct_el0();
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/* Generate 32-bit pattern: saving the 2 least significant bytes
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* in random_lo and random_hi
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*/
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uint16_t random_lo = (uint16_t)(
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(((uint64_t)return_addr) << 13) ^ frame_addr ^ cntpct
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);
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uint16_t random_hi = (uint16_t)(
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(((uint64_t)frame_addr) << 15) ^ return_addr ^ cntpct
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);
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return (((uint32_t)random_hi) << 16) | random_lo;
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}
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u_register_t plat_get_stack_protector_canary(void)
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{
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return plat_generate_random_number(); /* a 32-bit pattern is returned */
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}
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