1 /* 2 * Copyright (c) 2021-2025, 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/trf.h> 11 12 void trf_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.STE = b0 19 * Trace prohibited in Secure state unless overridden by the 20 * IMPLEMENTATION DEFINED authentication interface. 21 * 22 * MDCR_EL3.TTRF = b0 23 * Allow access of trace filter control registers from NS-EL2 24 * and NS-EL1 when NS-EL2 is implemented but not used 25 * 26 * MDCR_EL3.RLTE = b0 27 * Trace prohibited in Realm state, unless overridden by the 28 * IMPLEMENTATION DEFINED authentication interface. 29 */ 30 mdcr_el3_val &= ~(MDCR_STE_BIT | MDCR_TTRF_BIT | MDCR_RLTE_BIT); 31 write_ctx_reg(state, CTX_MDCR_EL3, mdcr_el3_val); 32 } 33 34 void trf_init_el2_unused(void) 35 { 36 /* 37 * MDCR_EL2.TTRF: Set to zero so that access to Trace 38 * Filter Control register TRFCR_EL1 at EL1 is not 39 * trapped to EL2. This bit is RES0 in versions of 40 * the architecture earlier than ARMv8.4. 41 * 42 */ 43 write_mdcr_el2(read_mdcr_el2() & ~MDCR_EL2_TTRF); 44 } 45