mirror of https://github.com/acidanthera/audk.git
cb87aada97
Unlike CPACR_EL1 whose reserved bits are solely RES0, CPTR_EL2 has some RES1 bits, and so we should not clear them unless we know what they mean. For example, when SVE was introduced, CPACR_EL1.ZEN occupied a RES0 field and thus 0 means trap (which is what we get at EL1), but CPTR_EL2.TZ occupied a RES1 field and thus 1 means trap, but we set it to 0, so the environment is inconsistent between EDK2 and EL1 and EL2. Another concrete case is for Morello, where the CEN/TC fields similarly gate access to capability register state, but also alter exception delivery and return, such that VBAR_ELx and ELR_ELx become capabilities. So long as software adheres to RES0/1 this is backwards-compatible, but since EDK2 does not do so here it inadvertently enables capability-based exception delivery and return and thus, when run at EL2, gets stuck in a trap loop when taking its first interrupt, but works just fine at EL1. Fix this by setting all the RES1 fields in CPTR_EL2, following the pattern for CPACR_EL1's non-zero initial value (due to setting FPEN so as to not trap on SIMD/FP use), tested by running ArmVirtQemu-AARCH64 (DEBUG) on Morello QEMU with EL2 enabled. Signed-off-by: Jessica Clarke <jrtc27@jrtc27.com> |
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| .. | ||
| ArchSec.c | ||
| Exception.S | ||
| Helper.S | ||
| ModuleEntryPoint.S | ||
| SwitchStack.S | ||