1 /* 2 * Copyright (c) 2022-2025, Arm Limited. All rights reserved. 3 * 4 * SPDX-License-Identifier: BSD-3-Clause 5 */ 6 7 #include <arch.h> 8 #include <arch_features.h> 9 #include <arch_helpers.h> 10 #include <lib/extensions/brbe.h> 11 12 void brbe_enable(cpu_context_t *ctx) 13 { 14 el3_state_t *state = get_el3state_ctx(ctx); 15 u_register_t mdcr_el3_val = read_ctx_reg(state, CTX_MDCR_EL3); 16 17 /* 18 * MDCR_EL3.SBRBE = 0b01 19 * Allows BRBE usage in non-secure world and prohibited in 20 * secure world. This is relied on by SMCCC_ARCH_FEATURE_AVAILABILITY. 21 * 22 * MDCR_EL3.{E3BREW, E3BREC} = 0b00 23 * Branch recording at EL3 is disabled 24 */ 25 mdcr_el3_val &= ~((MDCR_SBRBE(MDCR_SBRBE_ALL)) | MDCR_E3BREW_BIT | MDCR_E3BREC_BIT); 26 mdcr_el3_val |= (MDCR_SBRBE(MDCR_SBRBE_NS)); 27 write_ctx_reg(state, CTX_MDCR_EL3, mdcr_el3_val); 28 } 29