UefiCpuPkg/LoongArch64: Support NULL pointer detection

Add the LoongArch64 CPU-side support needed to make NULL pointer
detection effective after DXE page tables are established.

The platform memory map can reserve page 0, but DXE still needs the
CPU/MMU layer to enforce the requested memory attribute. Apply
EFI_MEMORY_RP to virtual address 0 after the CPU Arch protocol is
installed when PcdNullPointerDetectionPropertyMask BIT0 is enabled.
This updates the active DXE mapping after GCD setup.

Also update the LoongArch64 page-table attribute conversion path so a
requested no-read mapping clears PAGE_VALID. On the tested
LoongArchVirt/QEMU path, the no-read attribute alone does not reliably
raise a load fault for VA 0. Invalidating the PTE makes an assembly
load from address 0 raise a page-invalid load exception instead of
silently reading through the mapping.

This commit only changes the common LoongArch64 CPU/MMU support. The
LoongArchVirt platform memory-map policy is updated separately.

Signed-off-by: Dongyan Qian <qiandongyan@loongson.cn>

0 files changed, 0 insertions, 0 deletions