feat(cpufeat): add ENABLE_FEAT_LS64_ACCDATA
Armv8.6 introduced the FEAT_LS64 extension, which provides a 64 *byte*
store instruction. A related instruction is ST64BV0, which will replace
the lowest 32 bits of the data with a value taken from the ACCDATA_EL1
system register (so that EL0 cannot alter them).
Using that ST64BV0 instruction and accessing the ACCDATA_EL1 system
register is guarded by two SCR_EL3 bits, which we should set to avoid a
trap into EL3, when lower ELs use one of those.
Add the required bits and pieces to make this feature usable:
- Add the ENABLE_FEAT_LS64_ACCDATA build option (defaulting to 0).
- Add the CPUID and SCR_EL3 bit definitions associated with FEAT_LS64.
- Add a feature check to check for the existing four variants of the
LS64 feature and detect future extensions.
- Add code to save and restore the ACCDATA_EL1 register on
secure/non-secure context switches.
- Enable the feature with runtime detection for FVP and Arm FPGA.
Please note that the *basic* FEAT_LS64 feature does not feature any trap
bits, it's only the addition of the ACCDATA_EL1 system register that
adds these traps and the SCR_EL3 bits.
Change-Id: Ie3e2ca2d9c4fbbd45c0cc6089accbb825579138a
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 ec38d76..59188da 100644
--- a/include/arch/aarch64/arch_features.h
+++ b/include/arch/aarch64/arch_features.h
@@ -140,6 +140,8 @@
* +----------------------------+
* | FEAT_D128 |
* +----------------------------+
+ * | FEAT_LS64_ACCDATA |
+ * +----------------------------+
*/
__attribute__((always_inline))
@@ -421,6 +423,11 @@
CREATE_FEATURE_FUNCS(feat_sme2, id_aa64pfr1_el1, ID_AA64PFR1_EL1_SME_SHIFT,
ID_AA64PFR1_EL1_SME_MASK, SME2_IMPLEMENTED, ENABLE_SME2_FOR_NS)
+/* FEAT_LS64_ACCDATA: */
+CREATE_FEATURE_FUNCS(feat_ls64_accdata, id_aa64isar1_el1, ID_AA64ISAR1_LS64_SHIFT,
+ ID_AA64ISAR1_LS64_MASK, LS64_ACCDATA_IMPLEMENTED,
+ ENABLE_FEAT_LS64_ACCDATA)
+
/*******************************************************************************
* Function to get hardware granularity support
******************************************************************************/