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Kernel: MMU now takes flags when allocating pages

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Bananymous
2023-03-01 20:15:58 +02:00
parent 7d84f290a1
commit 9756de02ef
5 changed files with 70 additions and 54 deletions
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27
kernel/arch/i386/MMU.cpp
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@@ -7,9 +7,6 @@
#define MMU_DEBUG_PRINT 0
#define PRESENT (1 << 0)
#define READ_WRITE (1 << 1)
// bits 31-12 set
#define PAGE_MASK 0xfffff000
#define PAGE_SIZE 0x00001000
@@ -47,7 +44,7 @@ MMU::MMU()
for (int i = 0; i < 4; i++)
{
uint64_t* page_directory = allocate_page_aligned_page();
m_highest_paging_struct[i] = (uint64_t)page_directory | PRESENT;
m_highest_paging_struct[i] = (uint64_t)page_directory | Flags::Present;
}
// create and identity map first 4 MiB
@@ -56,9 +53,9 @@ MMU::MMU()
{
uint64_t* page_table = allocate_page_aligned_page();
for (uint64_t j = 0; j < 512; j++)
page_table[j] = (i << 21) | (j << 12) | READ_WRITE | PRESENT;
page_table[j] = (i << 21) | (j << 12) | Flags::ReadWrite | Flags::Present;
page_directory1[i] = (uint64_t)page_table | READ_WRITE | PRESENT;
page_directory1[i] = (uint64_t)page_table | Flags::ReadWrite | Flags::Present;
}
// dont map first page (0 -> 4 KiB) so that nullptr dereference
@@ -70,35 +67,37 @@ MMU::MMU()
asm volatile("movl %0, %%cr3" :: "r"(m_highest_paging_struct));
}
void MMU::allocate_page(uintptr_t address)
void MMU::allocate_page(uintptr_t address, uint8_t flags)
{
#if MMU_DEBUG_PRINT
dprintln("AllocatePage(0x{8H})", address & PAGE_MASK);
#endif
ASSERT(flags & Flags::Present);
uint32_t pdpte = (address & 0xC0000000) >> 30;
uint32_t pde = (address & 0x3FE00000) >> 21;
uint32_t pte = (address & 0x001FF000) >> 12;
uint64_t* page_directory = (uint64_t*)(m_highest_paging_struct[pdpte] & PAGE_MASK);
if (!(page_directory[pde] & PRESENT))
if (!(page_directory[pde] & Flags::Present))
{
uint64_t* page_table = allocate_page_aligned_page();
page_directory[pde] = (uint64_t)page_table | READ_WRITE | PRESENT;
page_directory[pde] = (uint64_t)page_table;
}
page_directory[pde] |= flags;
uint64_t* page_table = (uint64_t*)(page_directory[pde] & PAGE_MASK);
page_table[pte] = (address & PAGE_MASK) | READ_WRITE | PRESENT;
page_table[pte] = (address & PAGE_MASK) | Flags::ReadWrite | Flags::Present;
asm volatile("invlpg (%0)" :: "r"(address & PAGE_MASK) : "memory");
}
void MMU::allocate_range(uintptr_t address, ptrdiff_t size)
void MMU::allocate_range(uintptr_t address, ptrdiff_t size, uint8_t flags)
{
uintptr_t s_page = address & PAGE_MASK;
uintptr_t e_page = (address + size - 1) & PAGE_MASK;
for (uintptr_t page = s_page; page <= e_page; page += PAGE_SIZE)
allocate_page(page);
allocate_page(page, flags);
}
void MMU::unallocate_page(uintptr_t address)
@@ -112,11 +111,11 @@ void MMU::unallocate_page(uintptr_t address)
uint32_t pte = (address & 0x001FF000) >> 12;
uint64_t* page_directory = (uint64_t*)(m_highest_paging_struct[pdpte] & PAGE_MASK);
if (!(page_directory[pde] & PRESENT))
if (!(page_directory[pde] & Flags::Present))
return;
uint64_t* page_table = (uint64_t*)(page_directory[pde] & PAGE_MASK);
if (!(page_table[pte] & PRESENT))
if (!(page_table[pte] & Flags::Present))
return;
page_table[pte] = 0;