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Cycle through multiple tasks in multiple processes

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This commit is contained in:
Drew Galbraith 2023-05-18 13:56:54 -07:00
parent 7a3b4d2d42
commit d3024211a7
6 changed files with 56 additions and 12 deletions
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19
zion/memory/paging_util.cpp
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@ -98,20 +98,37 @@ void MapPage(uint64_t virt, uint64_t phys) {
*PageTableEntry(virt) = PageAlign(phys) | PRESENT_BIT | READ_WRITE_BIT;
ZeroOutPage(reinterpret_cast<uint64_t*>(virt));
}
uint64_t Pml4Index(uint64_t addr) { return (addr >> PML_OFFSET) & 0x1FF; }
} // namespace
void InitPaging() {
uint64_t pml4_addr = 0;
asm volatile("mov %%cr3, %0;" : "=r"(pml4_addr));
InitializePml4(pml4_addr);
uint64_t* pml4_virtual =
reinterpret_cast<uint64_t*>(boot::GetHigherHalfDirectMap() + pml4_addr);
uint64_t recursive_entry = pml4_addr | PRESENT_BIT | READ_WRITE_BIT;
pml4_virtual[0x1FE] = recursive_entry;
}
void InitializePml4(uint64_t pml4_physical_addr) {
uint64_t* pml4_virtual = reinterpret_cast<uint64_t*>(
boot::GetHigherHalfDirectMap() + pml4_physical_addr);
// Map the recursive entry.
uint64_t recursive_entry = pml4_physical_addr | PRESENT_BIT | READ_WRITE_BIT;
pml4_virtual[0x1FE] = recursive_entry;
// Map the kernel entry.
// This should contain the heap at 0xFFFFFFFF'40000000
uint64_t kernel_addr = 0xFFFFFFFF'80000000;
pml4_virtual[Pml4Index(kernel_addr)] = *Pml4Entry(kernel_addr);
// Map the HHDM.
// This is necessary to access values off of the kernel stack.
uint64_t hhdm = boot::GetHigherHalfDirectMap();
pml4_virtual[Pml4Index(hhdm)] = *Pml4Entry(hhdm);
}
void AllocatePage(uint64_t addr) {