refactor(trf): enable FEAT_TRF for FEAT_STATE_CHECKED

At the moment we only support FEAT_TRF to be either unconditionally
compiled in, or to be not supported at all.

Add support for runtime detection (ENABLE_TRF_FOR_NS=2), by splitting
is_feat_trf_present() into an ID register reading function and a second
function to report the support status. That function considers both
build time settings and runtime information (if needed), and is used
before we access TRF related registers.
Also move the context saving code from assembly to C, and use the new
is_feat_trf_supported() function to guard its execution.

The FVP platform decided to compile in support unconditionally (=1),
even though FEAT_TRF is an ARMv8.4 feature, so is not available with the
FVP model's default command line.
Change that to the now supported dynamic option (=2), so the right
decision can be made by the code at runtime.

Change-Id: Ia97b01adbe24970a4d837afd463dc5506b7295a3
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

3 files changed, 13 insertions, 36 deletions

diff --git a/lib/el3_runtime/aarch32/context_mgmt.c b/lib/el3_runtime/aarch32/context_mgmt.c
index af8edf598..e494a86cf 100644
--- a/lib/el3_runtime/aarch32/context_mgmt.c
+++ b/lib/el3_runtime/aarch32/context_mgmt.c
@@ -11,6 +11,7 @@
 #include <platform_def.h>
 
 #include <arch.h>
+#include <arch_features.h>
 #include <arch_helpers.h>
 #include <common/bl_common.h>
 #include <context.h>
@@ -143,9 +144,9 @@ static void enable_extensions_nonsecure(bool el2_unused)
 	sys_reg_trace_enable();
 #endif /* ENABLE_SYS_REG_TRACE_FOR_NS */
 
-#if ENABLE_TRF_FOR_NS
-	trf_enable();
-#endif /* ENABLE_TRF_FOR_NS */
+	if (is_feat_trf_supported()) {
+		trf_enable();
+	}
 #endif
 }
 
diff --git a/lib/el3_runtime/aarch64/context.S b/lib/el3_runtime/aarch64/context.S
index 722b8ae21..d43914848 100644
--- a/lib/el3_runtime/aarch64/context.S
+++ b/lib/el3_runtime/aarch64/context.S
@@ -41,10 +41,6 @@
 	.global	el2_sysregs_context_save_nv2
 	.global	el2_sysregs_context_restore_nv2
 #endif /* CTX_INCLUDE_NEVE_REGS */
-#if ENABLE_TRF_FOR_NS
-	.global	el2_sysregs_context_save_trf
-	.global	el2_sysregs_context_restore_trf
-#endif /* ENABLE_TRF_FOR_NS */
 #if ENABLE_FEAT_CSV2_2
 	.global	el2_sysregs_context_save_csv2
 	.global	el2_sysregs_context_restore_csv2
@@ -536,26 +532,6 @@ func el2_sysregs_context_restore_nv2
 endfunc el2_sysregs_context_restore_nv2
 #endif /* CTX_INCLUDE_NEVE_REGS */
 
-#if ENABLE_TRF_FOR_NS
-func el2_sysregs_context_save_trf
-	/*
-	 * TRFCR_EL2 register is saved only when FEAT_TRF is supported.
-	 */
-	mrs	x12, TRFCR_EL2
-	str	x12, [x0, #CTX_TRFCR_EL2]
-	ret
-endfunc el2_sysregs_context_save_trf
-
-func el2_sysregs_context_restore_trf
-	/*
-	 * TRFCR_EL2 register is restored only when FEAT_TRF is supported.
-	 */
-	ldr	x12, [x0, #CTX_TRFCR_EL2]
-	msr	TRFCR_EL2, x12
-	ret
-endfunc el2_sysregs_context_restore_trf
-#endif /* ENABLE_TRF_FOR_NS */
-
 #if ENABLE_FEAT_CSV2_2
 func el2_sysregs_context_save_csv2
 	/*
diff --git a/lib/el3_runtime/aarch64/context_mgmt.c b/lib/el3_runtime/aarch64/context_mgmt.c
index 54e257b75..4d2079d23 100644
--- a/lib/el3_runtime/aarch64/context_mgmt.c
+++ b/lib/el3_runtime/aarch64/context_mgmt.c
@@ -507,9 +507,9 @@ static void manage_extensions_nonsecure(bool el2_unused, cpu_context_t *ctx)
 	sys_reg_trace_enable(ctx);
 #endif /* ENABLE_SYS_REG_TRACE_FOR_NS */
 
-#if ENABLE_TRF_FOR_NS
-	trf_enable();
-#endif /* ENABLE_TRF_FOR_NS */
+	if (is_feat_trf_supported()) {
+		trf_enable();
+	}
 #endif
 }
 
@@ -875,9 +875,9 @@ void cm_el2_sysregs_context_save(uint32_t security_state)
 #if CTX_INCLUDE_NEVE_REGS
 		el2_sysregs_context_save_nv2(el2_sysregs_ctx);
 #endif
-#if ENABLE_TRF_FOR_NS
-		el2_sysregs_context_save_trf(el2_sysregs_ctx);
-#endif
+		if (is_feat_trf_supported()) {
+			write_ctx_reg(el2_sysregs_ctx, CTX_TRFCR_EL2, read_trfcr_el2());
+		}
 #if ENABLE_FEAT_CSV2_2
 		el2_sysregs_context_save_csv2(el2_sysregs_ctx);
 #endif
@@ -935,9 +935,9 @@ void cm_el2_sysregs_context_restore(uint32_t security_state)
 #if CTX_INCLUDE_NEVE_REGS
 		el2_sysregs_context_restore_nv2(el2_sysregs_ctx);
 #endif
-#if ENABLE_TRF_FOR_NS
-		el2_sysregs_context_restore_trf(el2_sysregs_ctx);
-#endif
+		if (is_feat_trf_supported()) {
+			write_trfcr_el2(read_ctx_reg(el2_sysregs_ctx, CTX_TRFCR_EL2));
+		}
 #if ENABLE_FEAT_CSV2_2
 		el2_sysregs_context_restore_csv2(el2_sysregs_ctx);
 #endif