refactor(cpufeat): enable SYS_REG_TRACE for FEAT_STATE_CHECKED
At the moment we only support access to the trace unit by system
registers (SYS_REG_TRACE) to be either unconditionally compiled in, or
to be not supported at all.
Add support for runtime detection (ENABLE_SYS_REG_TRACE_FOR_NS=2), by
adding is_feat_sys_reg_trace_supported(). That function considers both
build time settings and runtime information (if needed), and is used
before we access SYS_REG_TRACE related registers.
The FVP platform decided to compile in support unconditionally (=1),
even though this is an optional feature, so it 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: I450a574a4f6bd9fc269887037049c94c906f54b2
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/include/arch/aarch64/arch_features.h b/include/arch/aarch64/arch_features.h
index f1a13d2..ad938ae 100644
--- a/include/arch/aarch64/arch_features.h
+++ b/include/arch/aarch64/arch_features.h
@@ -320,6 +320,24 @@
ID_AA64PFR0_DIT_MASK) == ID_AA64PFR0_DIT_SUPPORTED);
}
+static inline unsigned int read_feat_tracever_id_field(void)
+{
+ return ISOLATE_FIELD(read_id_aa64dfr0_el1(), ID_AA64DFR0_TRACEVER);
+}
+
+static inline bool is_feat_sys_reg_trace_supported(void)
+{
+ if (ENABLE_SYS_REG_TRACE_FOR_NS == FEAT_STATE_DISABLED) {
+ return false;
+ }
+
+ if (ENABLE_SYS_REG_TRACE_FOR_NS == FEAT_STATE_ALWAYS) {
+ return true;
+ }
+
+ return read_feat_tracever_id_field() != 0U;
+}
+
/*************************************************************************
* Function to identify the presence of FEAT_TRF (TraceLift)
************************************************************************/