feat(brbe): add BRBE support for NS world
This patch enables access to the branch record buffer control registers
in non-secure EL2 and EL1 using the new build option ENABLE_BRBE_FOR_NS.
It is disabled for all secure world, and cannot be used with ENABLE_RME.
This option is disabled by default, however, the FVP platform makefile
enables it for FVP builds.
Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: I576a49d446a8a73286ea6417c16bd0b8de71fca0
diff --git a/Makefile b/Makefile
index a6cb013..90fb28b 100644
--- a/Makefile
+++ b/Makefile
@@ -135,6 +135,10 @@
ifneq (${ENABLE_PIE},0)
$(error ENABLE_RME does not support PIE)
endif
+# RME doesn't support BRBE
+ifneq (${ENABLE_BRBE_FOR_NS},0)
+ $(error ENABLE_RME does not support BRBE.)
+endif
# RME requires AARCH64
ifneq (${ARCH},aarch64)
$(error ENABLE_RME requires AArch64)
@@ -777,8 +781,10 @@
endif
endif
-# SME/SVE only supported on AArch64
+# Ensure that no Aarch64-only features are enabled in Aarch32 build
ifeq (${ARCH},aarch32)
+
+ # SME/SVE only supported on AArch64
ifeq (${ENABLE_SME_FOR_NS},1)
$(error "ENABLE_SME_FOR_NS cannot be used with ARCH=aarch32")
endif
@@ -786,6 +792,12 @@
# Warning instead of error due to CI dependency on this
$(error "ENABLE_SVE_FOR_NS cannot be used with ARCH=aarch32")
endif
+
+ # BRBE is not supported in Aarch32
+ ifeq (${ENABLE_BRBE_FOR_NS},1)
+ $(error "ENABLE_BRBE_FOR_NS cannot be used with ARCH=aarch32")
+ endif
+
endif
# Ensure ENABLE_RME is not used with SME
@@ -1032,6 +1044,7 @@
COT_DESC_IN_DTB \
USE_SP804_TIMER \
PSA_FWU_SUPPORT \
+ ENABLE_BRBE_FOR_NS \
ENABLE_TRBE_FOR_NS \
ENABLE_SYS_REG_TRACE_FOR_NS \
ENABLE_MPMM \
@@ -1172,6 +1185,7 @@
NR_OF_FW_BANKS \
NR_OF_IMAGES_IN_FW_BANK \
PSA_FWU_SUPPORT \
+ ENABLE_BRBE_FOR_NS \
ENABLE_TRBE_FOR_NS \
ENABLE_SYS_REG_TRACE_FOR_NS \
ENABLE_TRF_FOR_NS \
diff --git a/bl31/bl31.mk b/bl31/bl31.mk
index 214cf2f..3964469 100644
--- a/bl31/bl31.mk
+++ b/bl31/bl31.mk
@@ -115,6 +115,10 @@
BL31_SOURCES += lib/extensions/trbe/trbe.c
endif
+ifeq (${ENABLE_BRBE_FOR_NS},1)
+BL31_SOURCES += lib/extensions/brbe/brbe.c
+endif
+
ifeq (${ENABLE_SYS_REG_TRACE_FOR_NS},1)
BL31_SOURCES += lib/extensions/sys_reg_trace/aarch64/sys_reg_trace.c
endif
diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index 585b2a1..d2cda4d 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -973,6 +973,11 @@
functions that wait for an arbitrary time length (udelay and mdelay). The
default value is 0.
+- ``ENABLE_BRBE_FOR_NS``: This flag enables access to the branch record buffer
+ registers from NS ELs when FEAT_BRBE is implemented. BRBE is an optional
+ architectural feature for AArch64. The default is 0 and it is automatically
+ disabled when the target architecture is AArch32.
+
- ``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
diff --git a/include/arch/aarch64/arch.h b/include/arch/aarch64/arch.h
index b4608ae..bbbc77a 100644
--- a/include/arch/aarch64/arch.h
+++ b/include/arch/aarch64/arch.h
@@ -234,6 +234,11 @@
#define ID_AA64DFR0_MTPMU_MASK ULL(0xf)
#define ID_AA64DFR0_MTPMU_SUPPORTED ULL(1)
+/* ID_AA64DFR0_EL1.BRBE definitions */
+#define ID_AA64DFR0_BRBE_SHIFT U(52)
+#define ID_AA64DFR0_BRBE_MASK ULL(0xf)
+#define ID_AA64DFR0_BRBE_SUPPORTED ULL(1)
+
/* ID_AA64ISAR0_EL1 definitions */
#define ID_AA64ISAR0_RNDR_SHIFT U(60)
#define ID_AA64ISAR0_RNDR_MASK ULL(0xf)
@@ -512,6 +517,8 @@
#define MDCR_EnPMSN_BIT (ULL(1) << 36)
#define MDCR_MPMX_BIT (ULL(1) << 35)
#define MDCR_MCCD_BIT (ULL(1) << 34)
+#define MDCR_SBRBE_SHIFT U(32)
+#define MDCR_SBRBE_MASK ULL(0x3)
#define MDCR_NSTB(x) ((x) << 24)
#define MDCR_NSTB_EL1 ULL(0x3)
#define MDCR_NSTBE (ULL(1) << 26)
diff --git a/include/lib/extensions/brbe.h b/include/lib/extensions/brbe.h
new file mode 100644
index 0000000..aac1ace
--- /dev/null
+++ b/include/lib/extensions/brbe.h
@@ -0,0 +1,12 @@
+/*
+ * Copyright (c) 2022, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef BRBE_H
+#define BRBE_H
+
+void brbe_enable(void);
+
+#endif /* BRBE_H */
diff --git a/lib/el3_runtime/aarch64/context_mgmt.c b/lib/el3_runtime/aarch64/context_mgmt.c
index 47e7d8c..449f120 100644
--- a/lib/el3_runtime/aarch64/context_mgmt.c
+++ b/lib/el3_runtime/aarch64/context_mgmt.c
@@ -20,6 +20,7 @@
#include <lib/el3_runtime/context_mgmt.h>
#include <lib/el3_runtime/pubsub_events.h>
#include <lib/extensions/amu.h>
+#include <lib/extensions/brbe.h>
#include <lib/extensions/mpam.h>
#include <lib/extensions/sme.h>
#include <lib/extensions/spe.h>
@@ -469,6 +470,10 @@
trbe_enable();
#endif /* ENABLE_TRBE_FOR_NS */
+#if ENABLE_BRBE_FOR_NS
+ brbe_enable();
+#endif /* ENABLE_BRBE_FOR_NS */
+
#if ENABLE_SYS_REG_TRACE_FOR_NS
sys_reg_trace_enable(ctx);
#endif /* ENABLE_SYS_REG_TRACE_FOR_NS */
diff --git a/lib/extensions/brbe/brbe.c b/lib/extensions/brbe/brbe.c
new file mode 100644
index 0000000..6975b04
--- /dev/null
+++ b/lib/extensions/brbe/brbe.c
@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2022, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch.h>
+#include <arch_helpers.h>
+
+static bool brbe_supported(void)
+{
+ uint64_t features;
+
+ features = read_id_aa64dfr0_el1() >> ID_AA64DFR0_BRBE_SHIFT;
+ return ((features & ID_AA64DFR0_BRBE_MASK) ==
+ ID_AA64DFR0_BRBE_SUPPORTED);
+}
+
+void brbe_enable(void)
+{
+ uint64_t val;
+
+ if (brbe_supported()) {
+ /*
+ * MDCR_EL3.SBRBE = 0b01
+ *
+ * Allows BRBE usage in non-secure world and prohibited in
+ * secure world.
+ */
+ val = read_mdcr_el3();
+ val &= ~(MDCR_SBRBE_MASK << MDCR_SBRBE_SHIFT);
+ val |= (0x1UL << MDCR_SBRBE_SHIFT);
+ write_mdcr_el3(val);
+ }
+}
diff --git a/make_helpers/defaults.mk b/make_helpers/defaults.mk
index 7f92640..6e57237 100644
--- a/make_helpers/defaults.mk
+++ b/make_helpers/defaults.mk
@@ -440,6 +440,11 @@
override ENABLE_TRBE_FOR_NS := 0
endif
+# By default, disable access to branch record buffer control registers from NS
+# lower ELs i.e. NS-EL2, or NS-EL1 if NS-EL2 implemented but unused
+# if FEAT_BRBE is implemented.
+ENABLE_BRBE_FOR_NS := 0
+
# 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.
diff --git a/plat/arm/board/fvp/platform.mk b/plat/arm/board/fvp/platform.mk
index 19f913e..d89e91f 100644
--- a/plat/arm/board/fvp/platform.mk
+++ b/plat/arm/board/fvp/platform.mk
@@ -389,6 +389,15 @@
# enable trace buffer control registers access to NS by default
ENABLE_TRBE_FOR_NS := 1
+# enable branch record buffer control registers access in NS by default
+# only enable for aarch64
+# do not enable when ENABLE_RME=1
+ifeq (${ARCH}, aarch64)
+ifeq (${ENABLE_RME},0)
+ ENABLE_BRBE_FOR_NS := 1
+endif
+endif
+
# enable trace system registers access to NS by default
ENABLE_SYS_REG_TRACE_FOR_NS := 1