blob: c8471190a99ef816a249020d366cb07faa9ac9d6 [file] [log] [blame]
/*
* Copyright (c) 2019, Arm Limited. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <cdefs.h>
#include <stdint.h>
/*
* Instruction pointer authentication key A. The low 64-bit are at [0], and the
* high bits at [1]. They are run-time constants so they are placed in the
* rodata section. They are written before MMU is turned on and the permissions
* are effective.
*/
uint64_t plat_apiakey[2] __section("rodata.apiakey");
/*
* This is only a toy implementation to generate a seemingly random 128-bit key
* from sp and x30 values. A production system must re-implement this function
* to generate keys from a reliable randomness source.
*/
uint64_t *plat_init_apiakey(void)
{
uintptr_t return_addr = (uintptr_t)__builtin_return_address(0U);
uintptr_t frame_addr = (uintptr_t)__builtin_frame_address(0U);
plat_apiakey[0] = (return_addr << 13) ^ frame_addr;
plat_apiakey[1] = (frame_addr << 15) ^ return_addr;
return plat_apiakey;
}