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kernel/x86_64: Clear the lower half of the kernel PML4 in LA57 mode.

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It also has an identity mapping that needs to be removed,
same as the PML5.
This commit is contained in:
Augustin Cavalier
2025-03-12 12:20:27 -04:00
parent ed8ca68825
commit 92e002641e
1 changed files with 10 additions and 5 deletions
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src/system/kernel/arch/x86/paging/64bit/X86PagingMethod64Bit.cpp
+10 -5
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@@ -67,15 +67,20 @@ X86PagingMethod64Bit::Init(kernel_args* args,
if (x86_check_feature(IA32_FEATURE_AMD_EXT_NX, FEATURE_EXT_AMD))
call_all_cpus_sync(&_EnableExecutionDisable, NULL);
// Ensure that the user half of the address space is clear. This removes
// the temporary identity mapping made by the boot loader.
memset(fKernelVirtualPMLTop, 0, sizeof(uint64) * 256);
arch_cpu_global_TLB_invalidate();
// Create the physical page mapper.
mapped_physical_page_ops_init(args, fPhysicalPageMapper,
fKernelPhysicalPageMapper);
// Ensure that the user half of the address space is clear. This removes
// the temporary identity mapping made by the boot loader.
if (la57) {
uint64* virtualPML4 = (uint64*)fKernelPhysicalPageMapper->GetPageTableAt(
*fKernelVirtualPMLTop & X86_64_PML5E_ADDRESS_MASK);
memset(virtualPML4, 0, sizeof(uint64) * 256);
}
memset(fKernelVirtualPMLTop, 0, sizeof(uint64) * 256);
arch_cpu_global_TLB_invalidate();
*_physicalPageMapper = fPhysicalPageMapper;
return B_ERROR;
}