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[zion] Add utility to zero out a page when allocating one.

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This commit is contained in:
Drew Galbraith 2023-06-19 23:44:33 -07:00
parent 0b9e0adfbb
commit 164309eada
3 changed files with 25 additions and 19 deletions
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23
zion/memory/paging_util.cpp
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@ -24,16 +24,6 @@
namespace {
uint64_t PageAlign(uint64_t addr) { return addr & ~0xFFF; }
uint64_t* PageAlign(uint64_t* addr) {
return reinterpret_cast<uint64_t*>(reinterpret_cast<uint64_t>(addr) & ~0xFFF);
}
void ZeroOutPage(uint64_t* ptr) {
ptr = PageAlign(ptr);
for (uint64_t i = 0; i < 512; i++) {
ptr[i] = 0;
}
}
uint64_t ShiftForEntryIndexing(uint64_t addr, uint64_t offset) {
addr &= ~0xFFFF0000'00000000;
@ -126,21 +116,18 @@ void MapPage(uint64_t cr3, uint64_t vaddr, uint64_t paddr) {
uint64_t* pml4_entry = Pml4Entry(cr3, vaddr);
if (!(*pml4_entry & PRESENT_BIT)) {
uint64_t page = phys_mem::AllocatePage();
uint64_t page = phys_mem::AllocateAndZeroPage();
*pml4_entry = page | access_bits;
ZeroOutPage(PageDirectoryPointerEntry(*pml4_entry, vaddr));
}
uint64_t* pdp_entry = PageDirectoryPointerEntry(*pml4_entry, vaddr);
if (!(*pdp_entry & PRESENT_BIT)) {
uint64_t page = phys_mem::AllocatePage();
uint64_t page = phys_mem::AllocateAndZeroPage();
*pdp_entry = page | access_bits;
ZeroOutPage(PageDirectoryEntry(*pdp_entry, vaddr));
}
uint64_t* pd_entry = PageDirectoryEntry(*pdp_entry, vaddr);
if (!(*pd_entry & PRESENT_BIT)) {
uint64_t page = phys_mem::AllocatePage();
uint64_t page = phys_mem::AllocateAndZeroPage();
*(pd_entry) = page | access_bits;
ZeroOutPage(PageTableEntry(*pd_entry, vaddr));
}
uint64_t* pt_entry = PageTableEntry(*pd_entry, vaddr);
@ -158,9 +145,7 @@ uint64_t AllocatePageIfNecessary(uint64_t addr) {
return phys;
}
phys = phys_mem::AllocatePage();
// FIXME: Maybe move this to the physical memory allocator.
ZeroOutPage(
reinterpret_cast<uint64_t*>(boot::GetHigherHalfDirectMap() + phys));
MapPage(cr3, addr, phys);
return phys;
}