Merge changes from topic "TrcDbgExt" into integration

* changes:
  feat(plat/fvp): enable trace extension features by default
  feat(trf): enable trace filter control register access from lower NS EL
  feat(trf): initialize trap settings of trace filter control registers access
  feat(sys_reg_trace): enable trace system registers access from lower NS ELs
  feat(sys_reg_trace): initialize trap settings of trace system registers access
  feat(trbe): enable access to trace buffer control registers from lower NS EL
  feat(trbe): initialize trap settings of trace buffer control registers access

Makefile

@@ -968,6 +968,9 @@ $(eval $(call assert_booleans,\
         ENABLE_FEAT_RNG \
         ENABLE_FEAT_SB \
         PSA_FWU_SUPPORT \
+        ENABLE_TRBE_FOR_NS \
+        ENABLE_SYS_REG_TRACE_FOR_NS \
+        ENABLE_TRF_FOR_NS \
 )))
 
 $(eval $(call assert_numerics,\
@@ -1068,6 +1071,9 @@ $(eval $(call add_defines,\
         NR_OF_FW_BANKS \
         NR_OF_IMAGES_IN_FW_BANK \
         PSA_FWU_SUPPORT \
+        ENABLE_TRBE_FOR_NS \
+        ENABLE_SYS_REG_TRACE_FOR_NS \
+        ENABLE_TRF_FOR_NS \
 )))
 
 ifeq (${SANITIZE_UB},trap)

bl31/bl31.mk

@@ -90,6 +90,18 @@ ifeq (${ENABLE_MPAM_FOR_LOWER_ELS},1)
 BL31_SOURCES		+=	lib/extensions/mpam/mpam.c
 endif
 
+ifeq (${ENABLE_TRBE_FOR_NS},1)
+BL31_SOURCES		+=	lib/extensions/trbe/trbe.c
+endif
+
+ifeq (${ENABLE_SYS_REG_TRACE_FOR_NS},1)
+BL31_SOURCES		+=      lib/extensions/sys_reg_trace/aarch64/sys_reg_trace.c
+endif
+
+ifeq (${ENABLE_TRF_FOR_NS},1)
+BL31_SOURCES		+=	lib/extensions/trf/aarch64/trf.c
+endif
+
 ifeq (${WORKAROUND_CVE_2017_5715},1)
 BL31_SOURCES		+=	lib/cpus/aarch64/wa_cve_2017_5715_bpiall.S	\
 				lib/cpus/aarch64/wa_cve_2017_5715_mmu.S

bl32/sp_min/sp_min.mk

@@ -42,6 +42,14 @@ BL32_SOURCES		+=	services/std_svc/trng/trng_main.c	\
 				services/std_svc/trng/trng_entropy_pool.c
 endif
 
+ifeq (${ENABLE_SYS_REG_TRACE_FOR_NS},1)
+BL32_SOURCES		+=	lib/extensions/sys_reg_trace/aarch32/sys_reg_trace.c
+endif
+
+ifeq (${ENABLE_TRF_FOR_NS},1)
+BL32_SOURCES		+=	lib/extensions/trf/aarch32/trf.c
+endif
+
 BL32_LINKERFILE	:=	bl32/sp_min/sp_min.ld.S
 
 # Include the platform-specific SP_MIN Makefile

docs/getting_started/build-options.rst

@@ -775,6 +775,21 @@ Common build options
   functions that wait for an arbitrary time length (udelay and mdelay). The
   default value is 0.
 
+- ``ENABLE_TRBE_FOR_NS``: This flag is used to enable access of trace buffer
+  control registers from NS ELs, NS-EL2 or NS-EL1(when NS-EL2 is implemented
+  but unused) when FEAT_TRBE is implemented. TRBE is an optional architectural
+  feature for AArch64. The default is 0 and it is automatically disabled when
+  the target architecture is AArch32.
+
+- ``ENABLE_SYS_REG_TRACE_FOR_NS``: Boolean option to enable trace system
+  registers access from NS ELs, NS-EL2 or NS-EL1 (when NS-EL2 is implemented
+  but unused). This feature is available if trace unit such as ETMv4.x, and
+  ETE(extending ETM feature) is implemented. This flag is disabled by default.
+
+- ``ENABLE_TRF_FOR_NS``: Boolean option to enable trace filter control registers
+  access from NS ELs, NS-EL2 or NS-EL1 (when NS-EL2 is implemented but unused),
+  if FEAT_TRF is implemented. This flag is disabled by default.
+
 GICv3 driver options
 --------------------
 

include/arch/aarch32/arch.h

@@ -102,6 +102,16 @@
 /* CSSELR definitions */
 #define LEVEL_SHIFT		U(1)
 
+/* ID_DFR0_EL1 definitions */
+#define ID_DFR0_COPTRC_SHIFT		U(12)
+#define ID_DFR0_COPTRC_MASK		U(0xf)
+#define ID_DFR0_COPTRC_SUPPORTED	U(1)
+#define ID_DFR0_COPTRC_LENGTH		U(4)
+#define ID_DFR0_TRACEFILT_SHIFT		U(28)
+#define ID_DFR0_TRACEFILT_MASK		U(0xf)
+#define ID_DFR0_TRACEFILT_SUPPORTED	U(1)
+#define ID_DFR0_TRACEFILT_LENGTH	U(4)
+
 /* ID_DFR1_EL1 definitions */
 #define ID_DFR1_MTPMU_SHIFT	U(0)
 #define ID_DFR1_MTPMU_MASK	U(0xf)
@@ -173,6 +183,7 @@
 #define SDCR_SPD_DISABLE	U(0x2)
 #define SDCR_SPD_ENABLE		U(0x3)
 #define SDCR_SCCD_BIT		(U(1) << 23)
+#define SDCR_TTRF_BIT		(U(1) << 19)
 #define SDCR_SPME_BIT		(U(1) << 17)
 #define SDCR_RESET_VAL		U(0x0)
 #define SDCR_MTPME_BIT		(U(1) << 28)
@@ -516,6 +527,7 @@
 #define CTR		p15, 0, c0, c0, 1
 #define CNTFRQ		p15, 0, c14, c0, 0
 #define ID_MMFR4	p15, 0, c0, c2, 6
+#define ID_DFR0		p15, 0, c0, c1, 2
 #define ID_DFR1		p15, 0, c0, c3, 5
 #define ID_PFR0		p15, 0, c0, c1, 0
 #define ID_PFR1		p15, 0, c0, c1, 1

include/arch/aarch32/arch_helpers.h

@@ -217,6 +217,7 @@ DEFINE_SYSREG_RW_FUNCS(cpsr)
 DEFINE_COPROCR_READ_FUNC(mpidr, MPIDR)
 DEFINE_COPROCR_READ_FUNC(midr, MIDR)
 DEFINE_COPROCR_READ_FUNC(id_mmfr4, ID_MMFR4)
+DEFINE_COPROCR_READ_FUNC(id_dfr0, ID_DFR0)
 DEFINE_COPROCR_READ_FUNC(id_pfr0, ID_PFR0)
 DEFINE_COPROCR_READ_FUNC(id_pfr1, ID_PFR1)
 DEFINE_COPROCR_READ_FUNC(isr, ISR)
@@ -282,6 +283,7 @@ DEFINE_COPROCR_RW_FUNCS(icc_eoir1_el1, ICC_EOIR1)
 DEFINE_COPROCR_RW_FUNCS_64(icc_sgi0r_el1, ICC_SGI0R_EL1_64)
 DEFINE_COPROCR_WRITE_FUNC_64(icc_sgi1r, ICC_SGI1R_EL1_64)
 
+DEFINE_COPROCR_RW_FUNCS(sdcr, SDCR)
 DEFINE_COPROCR_RW_FUNCS(hdcr, HDCR)
 DEFINE_COPROCR_RW_FUNCS(cnthp_ctl, CNTHP_CTL)
 DEFINE_COPROCR_READ_FUNC(pmcr, PMCR)

include/arch/aarch32/el3_common_macros.S

@@ -63,11 +63,23 @@
 	 *  cp11 field is ignored, but is set to same value as cp10. The cp10
 	 *  field is set to allow access to Advanced SIMD and floating point
 	 *  features from both Security states.
+	 *
+	 * NSACR.NSTRCDIS: When system register trace implemented, Set to one
+	 *  so that NS System register accesses to all implemented trace
+	 *  registers are disabled.
+	 *  When system register trace is not implemented, this bit is RES0 and
+	 *  hence set to zero.
 	 * ---------------------------------------------------------------------
 	 */
 	ldcopr	r0, NSACR
 	and	r0, r0, #NSACR_IMP_DEF_MASK
 	orr	r0, r0, #(NSACR_RESET_VAL | NSACR_ENABLE_FP_ACCESS)
+	ldcopr	r1, ID_DFR0
+	ubfx	r1, r1, #ID_DFR0_COPTRC_SHIFT, #ID_DFR0_COPTRC_LENGTH
+	cmp	r1, #ID_DFR0_COPTRC_SUPPORTED
+	bne	1f
+	orr	r0, r0, #NSTRCDIS_BIT
+1:
 	stcopr	r0, NSACR
 	isb
 
@@ -119,9 +131,22 @@
 	 *  in Secure state. This bit is RES0 in versions of the architecture
 	 *  earlier than ARMv8.5, setting it to 1 doesn't have any effect on
 	 *  them.
+	 *
+	 * SDCR.TTRF: Set to one so that access to trace filter control
+	 *  registers in non-monitor mode generate Monitor trap exception,
+	 *  unless the access generates a higher priority exception when
+	 *  trace filter control(FEAT_TRF) is implemented.
+	 *  When FEAT_TRF is not implemented, this bit is RES0.
 	 * ---------------------------------------------------------------------
 	 */
-	ldr	r0, =(SDCR_RESET_VAL | SDCR_SPD(SDCR_SPD_DISABLE) | SDCR_SCCD_BIT)
+	ldr	r0, =((SDCR_RESET_VAL | SDCR_SPD(SDCR_SPD_DISABLE) | \
+		      SDCR_SCCD_BIT) & ~SDCR_TTRF_BIT)
+	ldcopr	r1, ID_DFR0
+	ubfx	r1, r1, #ID_DFR0_TRACEFILT_SHIFT, #ID_DFR0_TRACEFILT_LENGTH
+	cmp	r1, #ID_DFR0_TRACEFILT_SUPPORTED
+	bne	1f
+	orr	r0, r0, #SDCR_TTRF_BIT
+1:
 	stcopr	r0, SDCR
 
 	/* ---------------------------------------------------------------------

include/arch/aarch64/arch.h

@@ -188,10 +188,25 @@
 #define EL_IMPL_A64ONLY		ULL(1)
 #define EL_IMPL_A64_A32		ULL(2)
 
+/* ID_AA64DFR0_EL1.TraceVer definitions */
+#define ID_AA64DFR0_TRACEVER_SHIFT	U(4)
+#define ID_AA64DFR0_TRACEVER_MASK	ULL(0xf)
+#define ID_AA64DFR0_TRACEVER_SUPPORTED	ULL(1)
+#define ID_AA64DFR0_TRACEVER_LENGTH	U(4)
+#define ID_AA64DFR0_TRACEFILT_SHIFT	U(40)
+#define ID_AA64DFR0_TRACEFILT_MASK	U(0xf)
+#define ID_AA64DFR0_TRACEFILT_SUPPORTED	U(1)
+#define ID_AA64DFR0_TRACEFILT_LENGTH	U(4)
+
 /* ID_AA64DFR0_EL1.PMS definitions (for ARMv8.2+) */
 #define ID_AA64DFR0_PMS_SHIFT	U(32)
 #define ID_AA64DFR0_PMS_MASK	ULL(0xf)
 
+/* ID_AA64DFR0_EL1.TraceBuffer definitions */
+#define ID_AA64DFR0_TRACEBUFFER_SHIFT		U(44)
+#define ID_AA64DFR0_TRACEBUFFER_MASK		ULL(0xf)
+#define ID_AA64DFR0_TRACEBUFFER_SUPPORTED	ULL(1)
+
 /* ID_AA64DFR0_EL1.MTPMU definitions (for ARMv8.6+) */
 #define ID_AA64DFR0_MTPMU_SHIFT		U(48)
 #define ID_AA64DFR0_MTPMU_MASK		ULL(0xf)
@@ -442,6 +457,9 @@
 #define MDCR_EnPMSN_BIT		(ULL(1) << 36)
 #define MDCR_MPMX_BIT		(ULL(1) << 35)
 #define MDCR_MCCD_BIT		(ULL(1) << 34)
+#define MDCR_NSTB(x)		((x) << 24)
+#define MDCR_NSTB_EL1		ULL(0x3)
+#define MDCR_NSTBE		(ULL(1) << 26)
 #define MDCR_MTPME_BIT		(ULL(1) << 28)
 #define MDCR_TDCC_BIT		(ULL(1) << 27)
 #define MDCR_SCCD_BIT		(ULL(1) << 23)
@@ -465,6 +483,8 @@
 /* MDCR_EL2 definitions */
 #define MDCR_EL2_MTPME		(U(1) << 28)
 #define MDCR_EL2_HLP		(U(1) << 26)
+#define MDCR_EL2_E2TB(x)	((x) << 24)
+#define MDCR_EL2_E2TB_EL1	U(0x3)
 #define MDCR_EL2_HCCD		(U(1) << 23)
 #define MDCR_EL2_TTRF		(U(1) << 19)
 #define MDCR_EL2_HPMD		(U(1) << 17)

include/arch/aarch64/el3_common_macros.S

@@ -126,13 +126,31 @@
 	 *  Debug is not implemented this bit does not have any effect on the
 	 *  counters unless there is support for the implementation defined
 	 *  authentication interface ExternalSecureNoninvasiveDebugEnabled().
+	 *
+	 * MDCR_EL3.NSTB, MDCR_EL3.NSTBE: Set to zero so that Trace Buffer
+	 *  owning security state is Secure state. If FEAT_TRBE is implemented,
+	 *  accesses to Trace Buffer control registers at EL2 and EL1 in any
+	 *  security state generates trap exceptions to EL3.
+	 *  If FEAT_TRBE is not implemented, these bits are RES0.
+	 *
+	 * MDCR_EL3.TTRF: Set to one so that access to trace filter control
+	 *  registers in non-monitor mode generate EL3 trap exception,
+	 *  unless the access generates a higher priority exception when trace
+	 *  filter control(FEAT_TRF) is implemented.
+	 *  When FEAT_TRF is not implemented, this bit is RES0.
 	 * ---------------------------------------------------------------------
 	 */
 	mov_imm	x0, ((MDCR_EL3_RESET_VAL | MDCR_SDD_BIT | \
 		      MDCR_SPD32(MDCR_SPD32_DISABLE) | MDCR_SCCD_BIT | \
 		      MDCR_MCCD_BIT) & ~(MDCR_SPME_BIT | MDCR_TDOSA_BIT | \
-		      MDCR_TDA_BIT | MDCR_TPM_BIT))
+		      MDCR_TDA_BIT | MDCR_TPM_BIT | MDCR_NSTB(MDCR_NSTB_EL1) | \
+		      MDCR_NSTBE | MDCR_TTRF_BIT))
 
+	mrs	x1, id_aa64dfr0_el1
+	ubfx	x1, x1, #ID_AA64DFR0_TRACEFILT_SHIFT, #ID_AA64DFR0_TRACEFILT_LENGTH
+	cbz	x1, 1f
+	orr	x0, x0, #MDCR_TTRF_BIT
+1:
 	msr	mdcr_el3, x0
 
 	/* ---------------------------------------------------------------------
@@ -179,6 +197,12 @@
 	 * CPTR_EL3.TCPAC: Set to zero so that any accesses to CPACR_EL1,
 	 *  CPTR_EL2, CPACR, or HCPTR do not trap to EL3.
 	 *
+	 * CPTR_EL3.TTA: Set to one so that accesses to the trace system
+	 *  registers trap to EL3 from all exception levels and security
+	 *  states when system register trace is implemented.
+	 *  When system register trace is not implemented, this bit is RES0 and
+	 *  hence set to zero.
+	 *
 	 * CPTR_EL3.TTA: Set to zero so that System register accesses to the
 	 *  trace registers do not trap to EL3.
 	 *
@@ -194,6 +218,11 @@
 	 */
 
 	mov_imm x0, (CPTR_EL3_RESET_VAL & ~(TCPAC_BIT | TTA_BIT | TFP_BIT))
+	mrs	x1, id_aa64dfr0_el1
+	ubfx	x1, x1, #ID_AA64DFR0_TRACEVER_SHIFT, #ID_AA64DFR0_TRACEVER_LENGTH
+	cbz	x1, 1f
+	orr	x0, x0, #TTA_BIT
+1:
 	msr	cptr_el3, x0
 
 	/*

include/lib/extensions/sys_reg_trace.h

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef SYS_REG_TRACE_H
+#define SYS_REG_TRACE_H
+
+#include <context.h>
+
+#if __aarch64__
+void sys_reg_trace_enable(cpu_context_t *context);
+#else
+void sys_reg_trace_enable(void);
+#endif /* __aarch64__ */
+
+#endif /* SYS_REG_TRACE_H */

include/lib/extensions/trbe.h

@@ -0,0 +1,12 @@
+/*
+ * Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef TRBE_H
+#define TRBE_H
+
+void trbe_enable(void);
+
+#endif /* TRBE_H */

include/lib/extensions/trf.h

@@ -0,0 +1,12 @@
+/*
+ * Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef TRF_H
+#define TRF_H
+
+void trf_enable(void);
+
+#endif /* TRF_H */

lib/el3_runtime/aarch32/context_mgmt.c

@@ -16,6 +16,8 @@
 #include <context.h>
 #include <lib/el3_runtime/context_mgmt.h>
 #include <lib/extensions/amu.h>
+#include <lib/extensions/sys_reg_trace.h>
+#include <lib/extensions/trf.h>
 #include <lib/utils.h>
 
 /*******************************************************************************
@@ -136,6 +138,14 @@ static void enable_extensions_nonsecure(bool el2_unused)
 #if ENABLE_AMU
 	amu_enable(el2_unused);
 #endif
+
+#if ENABLE_SYS_REG_TRACE_FOR_NS
+	sys_reg_trace_enable();
+#endif /* ENABLE_SYS_REG_TRACE_FOR_NS */
+
+#if ENABLE_TRF_FOR_NS
+	trf_enable();
+#endif /* ENABLE_TRF_FOR_NS */
 #endif
 }
 

lib/el3_runtime/aarch64/context_mgmt.c

@@ -22,6 +22,9 @@
 #include <lib/extensions/mpam.h>
 #include <lib/extensions/spe.h>
 #include <lib/extensions/sve.h>
+#include <lib/extensions/sys_reg_trace.h>
+#include <lib/extensions/trbe.h>
+#include <lib/extensions/trf.h>
 #include <lib/extensions/twed.h>
 #include <lib/utils.h>
 
@@ -348,6 +351,19 @@ static void enable_extensions_nonsecure(bool el2_unused, cpu_context_t *ctx)
 #if ENABLE_MPAM_FOR_LOWER_ELS
 	mpam_enable(el2_unused);
 #endif
+
+#if ENABLE_TRBE_FOR_NS
+	trbe_enable();
+#endif /* ENABLE_TRBE_FOR_NS */
+
+#if ENABLE_SYS_REG_TRACE_FOR_NS
+	sys_reg_trace_enable(ctx);
+#endif /* ENABLE_SYS_REG_TRACE_FOR_NS */
+
+#if ENABLE_TRF_FOR_NS
+	trf_enable();
+#endif /* ENABLE_TRF_FOR_NS */
+
 #endif
 }
 
@@ -457,6 +473,8 @@ void cm_prepare_el3_exit(uint32_t security_state)
 			 * CPTR_EL2.TTA: Set to zero so that Non-secure System
 			 *  register accesses to the trace registers from both
 			 *  Execution states do not trap to EL2.
+			 *  If PE trace unit System registers are not implemented
+			 *  then this bit is reserved, and must be set to zero.
 			 *
 			 * CPTR_EL2.TFP: Set to zero so that Non-secure accesses
 			 *  to SIMD and floating-point functionality from both
@@ -565,6 +583,11 @@ void cm_prepare_el3_exit(uint32_t security_state)
 			 *
 			 * MDCR_EL2.HPMN: Set to value of PMCR_EL0.N which is the
 			 *  architecturally-defined reset value.
+			 *
+			 * MDCR_EL2.E2TB: Set to zero so that the trace Buffer
+			 *  owning exception level is NS-EL1 and, tracing is
+			 *  prohibited at NS-EL2. These bits are RES0 when
+			 *  FEAT_TRBE is not implemented.
 			 */
 			mdcr_el2 = ((MDCR_EL2_RESET_VAL | MDCR_EL2_HLP |
 				     MDCR_EL2_HPMD) |
@@ -574,7 +597,8 @@ void cm_prepare_el3_exit(uint32_t security_state)
 				     MDCR_EL2_TDRA_BIT | MDCR_EL2_TDOSA_BIT |
 				     MDCR_EL2_TDA_BIT | MDCR_EL2_TDE_BIT |
 				     MDCR_EL2_HPME_BIT | MDCR_EL2_TPM_BIT |
-				     MDCR_EL2_TPMCR_BIT);
+				     MDCR_EL2_TPMCR_BIT |
+				     MDCR_EL2_E2TB(MDCR_EL2_E2TB_EL1));
 
 			write_mdcr_el2(mdcr_el2);
 

lib/extensions/sys_reg_trace/aarch32/sys_reg_trace.c

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdbool.h>
+
+#include <arch.h>
+#include <arch_helpers.h>
+#include <lib/extensions/sys_reg_trace.h>
+
+static bool sys_reg_trace_supported(void)
+{
+	uint32_t features;
+
+	features = read_id_dfr0() >> ID_DFR0_COPTRC_SHIFT;
+	return ((features & ID_DFR0_COPTRC_MASK) ==
+		ID_DFR0_COPTRC_SUPPORTED);
+}
+
+void sys_reg_trace_enable(void)
+{
+	uint32_t val;
+
+	if (sys_reg_trace_supported()) {
+		/*
+		 * NSACR.NSTRCDIS = b0
+		 * enable NS system register access to implemented trace
+		 * registers.
+		 */
+		val = read_nsacr();
+		val &= ~NSTRCDIS_BIT;
+		write_nsacr(val);
+	}
+}

lib/extensions/sys_reg_trace/aarch64/sys_reg_trace.c

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdbool.h>
+
+#include <arch.h>
+#include <arch_helpers.h>
+#include <lib/extensions/sys_reg_trace.h>
+
+static bool sys_reg_trace_supported(void)
+{
+	uint64_t features;
+
+	features = read_id_aa64dfr0_el1() >> ID_AA64DFR0_TRACEVER_SHIFT;
+	return ((features & ID_AA64DFR0_TRACEVER_MASK) ==
+		ID_AA64DFR0_TRACEVER_SUPPORTED);
+}
+
+void sys_reg_trace_enable(cpu_context_t *ctx)
+{
+	uint64_t val;
+
+	if (sys_reg_trace_supported()) {
+		/* Retrieve CPTR_EL3 value from the given context 'ctx',
+		 * and update CPTR_EL3.TTA bit to 0.
+		 * This function is called while switching context to NS to
+		 * allow system trace register access to NS-EL2 and NS-EL1
+		 * when NS-EL2 is implemented but not used.
+		 */
+		val = read_ctx_reg(get_el3state_ctx(ctx), CTX_CPTR_EL3);
+		val &= ~TTA_BIT;
+		write_ctx_reg(get_el3state_ctx(ctx), CTX_CPTR_EL3, val);
+	}
+}

lib/extensions/trbe/trbe.c

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch.h>
+#include <arch_helpers.h>
+#include <lib/el3_runtime/pubsub.h>
+#include <lib/extensions/trbe.h>
+
+static void tsb_csync(void)
+{
+	/*
+	 * The assembler does not yet understand the tsb csync mnemonic
+	 * so use the equivalent hint instruction.
+	 */
+	__asm__ volatile("hint #18");
+}
+
+static bool trbe_supported(void)
+{
+	uint64_t features;
+
+	features = read_id_aa64dfr0_el1() >> ID_AA64DFR0_TRACEBUFFER_SHIFT;
+	return ((features & ID_AA64DFR0_TRACEBUFFER_MASK) ==
+		ID_AA64DFR0_TRACEBUFFER_SUPPORTED);
+}
+
+void trbe_enable(void)
+{
+	uint64_t val;
+
+	if (trbe_supported()) {
+		/*
+		 * MDCR_EL3.NSTB = 0b11
+		 * Allow access of trace buffer control registers from NS-EL1
+		 * and NS-EL2, tracing is prohibited in Secure and Realm state
+		 * (if implemented).
+		 */
+		val = read_mdcr_el3();
+		val |= MDCR_NSTB(MDCR_NSTB_EL1);
+		write_mdcr_el3(val);
+	}
+}
+
+static void *trbe_drain_trace_buffers_hook(const void *arg __unused)
+{
+	if (trbe_supported()) {
+		/*
+		 * Before switching from normal world to secure world
+		 * the trace buffers need to be drained out to memory. This is
+		 * required to avoid an invalid memory access when TTBR is switched
+		 * for entry to S-EL1.
+		 */
+		tsb_csync();
+		dsbnsh();
+	}
+
+	return (void *)0;
+}
+
+SUBSCRIBE_TO_EVENT(cm_entering_secure_world, trbe_drain_trace_buffers_hook);

lib/extensions/trf/aarch32/trf.c

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdbool.h>
+
+#include <arch.h>
+#include <arch_helpers.h>
+#include <lib/extensions/trf.h>
+
+static bool trf_supported(void)
+{
+	uint32_t features;
+
+	features = read_id_dfr0() >> ID_DFR0_TRACEFILT_SHIFT;
+	return ((features & ID_DFR0_TRACEFILT_MASK) ==
+		ID_DFR0_TRACEFILT_SUPPORTED);
+}
+
+void trf_enable(void)
+{
+	uint32_t val;
+
+	if (trf_supported()) {
+		/*
+		 * Allow access of trace filter control registers from
+		 * non-monitor mode
+		 */
+		val = read_sdcr();
+		val &= ~SDCR_TTRF_BIT;
+		write_sdcr(val);
+	}
+}

lib/extensions/trf/aarch64/trf.c

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdbool.h>
+
+#include <arch.h>
+#include <arch_helpers.h>
+#include <lib/extensions/trf.h>
+
+static bool trf_supported(void)
+{
+	uint64_t features;
+
+	features = read_id_aa64dfr0_el1() >> ID_AA64DFR0_TRACEFILT_SHIFT;
+	return ((features & ID_AA64DFR0_TRACEFILT_MASK) ==
+		ID_AA64DFR0_TRACEFILT_SUPPORTED);
+}
+
+void trf_enable(void)
+{
+	uint64_t val;
+
+	if (trf_supported()) {
+		/*
+		 * MDCR_EL3.TTRF = b0
+		 * Allow access of trace filter control registers from NS-EL2
+		 * and NS-EL1 when NS-EL2 is implemented but not used
+		 */
+		val = read_mdcr_el3();
+		val &= ~MDCR_TTRF_BIT;
+		write_mdcr_el3(val);
+	}
+}

make_helpers/defaults.mk

@@ -355,3 +355,24 @@ NR_OF_IMAGES_IN_FW_BANK		:= 1
 
 # Disable Firmware update support by default
 PSA_FWU_SUPPORT			:= 0
+
+# By default, disable access of trace buffer control registers from NS
+# lower ELs  i.e. NS-EL2, or NS-EL1 if NS-EL2 implemented but unused
+# if FEAT_TRBE is implemented.
+# Note FEAT_TRBE is only supported on AArch64 - therefore do not enable in
+# AArch32.
+ifneq (${ARCH},aarch32)
+    ENABLE_TRBE_FOR_NS		:= 0
+else
+    override ENABLE_TRBE_FOR_NS	:= 0
+endif
+
+# By default, disable access of trace system registers from NS lower
+# ELs  i.e. NS-EL2, or NS-EL1 if NS-EL2 implemented but unused if
+# system register trace is implemented.
+ENABLE_SYS_REG_TRACE_FOR_NS	:= 0
+
+# By default, disable trace filter control registers access to NS
+# lower ELs, i.e. NS-EL2, or NS-EL1 if NS-EL2 implemented but unused
+# if FEAT_TRF is implemented.
+ENABLE_TRF_FOR_NS		:= 0

plat/arm/board/fvp/platform.mk

@@ -378,3 +378,12 @@ endif
 # dynamically if TRUSTED_BOARD_BOOT is set.
 DYN_DISABLE_AUTH	:=	1
 endif
+
+# enable trace buffer control registers access to NS by default
+ENABLE_TRBE_FOR_NS		:= 1
+
+# enable trace system registers access to NS by default
+ENABLE_SYS_REG_TRACE_FOR_NS	:= 1
+
+# enable trace filter control registers access to NS by default
+ENABLE_TRF_FOR_NS		:= 1