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Kernel: kernel memory takes now full pml4e 

This allows flags to work properly
This commit is contained in:
Bananymous 2023-07-21 13:29:46 +03:00
parent 193ddaa2f6
commit faf4220b38
1 changed files with 30 additions and 42 deletions
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72
kernel/arch/x86_64/PageTable.cpp
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@ -19,9 +19,8 @@ namespace Kernel
static bool s_has_nxe = false;
static bool s_has_pge = false;
// Page Directories for kernel memory (KERNEL_OFFSET -> 0xFFFFFFFFFFFFFFFF)
static paddr_t s_global[(0xFFFFFFFFFFFFFFFF - KERNEL_OFFSET + 1) / (4096ull * 512ull * 512ull)] { };
static_assert(sizeof(s_global) / sizeof(*s_global) < 512);
// PML4 entry for kernel memory
static paddr_t s_global_pml4e = 0;
static constexpr inline bool is_canonical(uintptr_t addr)
{
@ -103,12 +102,13 @@ namespace Kernel
void PageTable::initialize_kernel()
{
for (uint32_t i = 0; i < sizeof(s_global) / sizeof(*s_global); i++)
{
ASSERT(s_global[i] == 0);
s_global[i] = V2P(allocate_zeroed_page_aligned_page());
}
map_kernel_memory();
ASSERT(s_global_pml4e == 0);
s_global_pml4e = V2P(allocate_zeroed_page_aligned_page());
m_highest_paging_struct = V2P(allocate_zeroed_page_aligned_page());
uint64_t* pml4 = (uint64_t*)P2V(m_highest_paging_struct);
pml4[511] = s_global_pml4e;
// Map (0 -> phys_kernel_end) to (KERNEL_OFFSET -> virt_kernel_end)
map_range_at(0, KERNEL_OFFSET, (uintptr_t)g_kernel_end - KERNEL_OFFSET, Flags::ReadWrite | Flags::Present);
@ -134,33 +134,24 @@ namespace Kernel
void PageTable::map_kernel_memory()
{
// Verify that kernel memory fits to single page directory pointer table
static_assert(0xFFFFFFFFFFFFFFFF - KERNEL_OFFSET < 4096ull * 512ull * 512ull * 512ull);
ASSERT(s_kernel);
ASSERT(s_global_pml4e);
ASSERT(m_highest_paging_struct == 0);
m_highest_paging_struct = V2P(allocate_zeroed_page_aligned_page());
constexpr uint64_t pml4e = (KERNEL_OFFSET >> 39) & 0x1FF;
constexpr uint64_t pdpte = (KERNEL_OFFSET >> 30) & 0x1FF;
uint64_t* kernel_pml4 = (uint64_t*)P2V(s_kernel->m_highest_paging_struct);
uint64_t* pml4 = (uint64_t*)P2V(m_highest_paging_struct);
pml4[pml4e] = V2P(allocate_zeroed_page_aligned_page());
pml4[pml4e] |= Flags::ReadWrite | Flags::Present;
uint64_t* pdpt = (uint64_t*)P2V(pml4[pml4e] & PAGE_ADDR_MASK);
for (uint64_t i = 0; pdpte + i < 512; i++)
pdpt[pdpte + i] = s_global[i] | (Flags::ReadWrite | Flags::Present);
pml4[511] = kernel_pml4[511];
}
PageTable::~PageTable()
{
// Verify that kernel memory fits to single page directory pointer table
static_assert(0xFFFFFFFFFFFFFFFF - KERNEL_OFFSET < 4096ull * 512ull * 512ull * 512ull);
constexpr uint64_t kernel_pml4e = (KERNEL_OFFSET >> 39) & 0x1FF;
constexpr uint64_t kernel_pdpte = (KERNEL_OFFSET >> 30) & 0x1FF;
uint64_t* pml4 = (uint64_t*)P2V(m_highest_paging_struct);
for (uint64_t pml4e = 0; pml4e < 512; pml4e++)
// NOTE: we only loop until 511 since the last one is the kernel memory
for (uint64_t pml4e = 0; pml4e < 511; pml4e++)
{
if (!(pml4[pml4e] & Flags::Present))
continue;
@ -169,8 +160,6 @@ namespace Kernel
{
if (!(pdpt[pdpte] & Flags::Present))
continue;
if (pml4e >= kernel_pml4e && pdpte >= kernel_pdpte)
break;
uint64_t* pd = (uint64_t*)P2V(pdpt[pdpte] & PAGE_ADDR_MASK);
for (uint64_t pde = 0; pde < 512; pde++)
{
@ -243,13 +232,6 @@ namespace Kernel
{
LockGuard _(m_lock);
uint64_t extra_flags = 0;
if (s_has_nxe && !(flags & Flags::Execute))
extra_flags |= 1ull << 63;
if (s_has_pge && this == s_kernel)
extra_flags |= 1ull << 8;
flags &= ~Flags::Execute;
if (vaddr && (vaddr >= KERNEL_OFFSET) != (this == s_kernel))
Kernel::panic("mapping {8H} to {8H}, kernel: {}", paddr, vaddr, this == s_kernel);
@ -258,7 +240,6 @@ namespace Kernel
ASSERT(paddr % PAGE_SIZE == 0);
ASSERT(vaddr % PAGE_SIZE == 0);
ASSERT(flags & Flags::Present);
uint64_t pml4e = (vaddr >> 39) & 0x1FF;
@ -266,32 +247,39 @@ namespace Kernel
uint64_t pde = (vaddr >> 21) & 0x1FF;
uint64_t pte = (vaddr >> 12) & 0x1FF;
uint64_t extra_flags = 0;
if (s_has_nxe && !(flags & Flags::Execute))
extra_flags |= 1ull << 63;
if (s_has_pge && pml4e == 511)
extra_flags |= 1ull << 8;
flags_t uwr_flags = flags & 0b111;
uint64_t* pml4 = (uint64_t*)P2V(m_highest_paging_struct);
if ((pml4[pml4e] & flags) != flags)
if ((pml4[pml4e] & uwr_flags) != uwr_flags)
{
if (!(pml4[pml4e] & Flags::Present))
pml4[pml4e] = V2P(allocate_zeroed_page_aligned_page());
pml4[pml4e] = (pml4[pml4e] & PAGE_ADDR_MASK) | flags;
pml4[pml4e] |= uwr_flags;
}
uint64_t* pdpt = (uint64_t*)P2V(pml4[pml4e] & PAGE_ADDR_MASK);
if ((pdpt[pdpte] & flags) != flags)
if ((pdpt[pdpte] & uwr_flags) != uwr_flags)
{
if (!(pdpt[pdpte] & Flags::Present))
pdpt[pdpte] = V2P(allocate_zeroed_page_aligned_page());
pdpt[pdpte] = (pdpt[pdpte] & PAGE_ADDR_MASK) | flags;
pdpt[pdpte] |= uwr_flags;
}
uint64_t* pd = (uint64_t*)P2V(pdpt[pdpte] & PAGE_ADDR_MASK);
if ((pd[pde] & flags) != flags)
if ((pd[pde] & uwr_flags) != uwr_flags)
{
if (!(pd[pde] & Flags::Present))
pd[pde] = V2P(allocate_zeroed_page_aligned_page());
pd[pde] = (pd[pde] & PAGE_ADDR_MASK) | flags;
pd[pde] |= uwr_flags;
}
uint64_t* pt = (uint64_t*)P2V(pd[pde] & PAGE_ADDR_MASK);
pt[pte] = paddr | flags | extra_flags;
pt[pte] = paddr | uwr_flags | extra_flags;
invalidate(canonicalize(vaddr));
}