feat(sys_reg_trace): initialize trap settings of trace system registers access

Trap bits of trace system registers access are in architecturally
UNKNOWN state at boot hence

1. Initialized trap bits to one to prohibit trace system registers
   accesses in lower ELs (EL2, EL1) in all security states when system
   trace registers are implemented.
2. These bits are RES0 in the absence of system trace register support
   and hence set it to zero to aligns with the Arm ARM reference
   recommendation,that mentions software must writes RES0 bits with
   all 0s.

Change-Id: I4b6c15cda882325273492895d72568b29de89ca3
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>

4 files changed, 36 insertions, 0 deletions

diff --git a/include/arch/aarch32/arch.h b/include/arch/aarch32/arch.h
index 54ec00953..5b160a227 100644
--- a/include/arch/aarch32/arch.h
+++ b/include/arch/aarch32/arch.h
@@ -102,6 +102,12 @@
 /* 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)
+
 /* ID_DFR1_EL1 definitions */
 #define ID_DFR1_MTPMU_SHIFT	U(0)
 #define ID_DFR1_MTPMU_MASK	U(0xf)
@@ -516,6 +522,7 @@
 #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
diff --git a/include/arch/aarch32/el3_common_macros.S b/include/arch/aarch32/el3_common_macros.S
index 7fff4c754..49e8518d3 100644
--- a/include/arch/aarch32/el3_common_macros.S
+++ b/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
 
diff --git a/include/arch/aarch64/arch.h b/include/arch/aarch64/arch.h
index 47e02ce43..2a3812394 100644
--- a/include/arch/aarch64/arch.h
+++ b/include/arch/aarch64/arch.h
@@ -188,6 +188,12 @@
 #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)
+
 /* ID_AA64DFR0_EL1.PMS definitions (for ARMv8.2+) */
 #define ID_AA64DFR0_PMS_SHIFT	U(32)
 #define ID_AA64DFR0_PMS_MASK	ULL(0xf)
diff --git a/include/arch/aarch64/el3_common_macros.S b/include/arch/aarch64/el3_common_macros.S
index 2aa22226f..18fe0de1e 100644
--- a/include/arch/aarch64/el3_common_macros.S
+++ b/include/arch/aarch64/el3_common_macros.S
@@ -186,6 +186,12 @@
 	 * 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.
 	 *
@@ -201,6 +207,11 @@
 	 */
 
 	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
 
 	/*