diff options
Diffstat (limited to 'kernel/src/arch/x86_64/paging.cpp')
| -rw-r--r-- | kernel/src/arch/x86_64/paging.cpp | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/kernel/src/arch/x86_64/paging.cpp b/kernel/src/arch/x86_64/paging.cpp new file mode 100644 index 0000000..3437889 --- /dev/null +++ b/kernel/src/arch/x86_64/paging.cpp @@ -0,0 +1,161 @@ +#include <cstdint> +#include <generic/arch.hpp> +#include <generic/bootloader/bootloader.hpp> +#include <generic/hhdm.hpp> +#include <generic/pmm.hpp> + +#define PTE_MASK_VALUE_5 0x000ffffffffffff000 +#define PTE_MASK_VALUE 0x000ffffffffff000 +#define PTE_PRESENT (1 << 0) +#define PTE_RW (1 << 1) +#define PTE_USER (1 << 2) +#define PTE_WC ((1 << 7) | (1 << 3)) +#define PTE_MMIO (1ull << 4) +#define LVL_PG_MASK (bootloader::bootloader->is_5_level_paging() ? PTE_MASK_VALUE_5 : PTE_MASK_VALUE) + +int level_to_index(std::uintptr_t virt, int level) { + if(bootloader::bootloader->is_5_level_paging()) { + switch (level) { + case 0: return PTE_INDEX(virt, 48); + case 1: return PTE_INDEX(virt, 39); + case 2: return PTE_INDEX(virt, 30); + case 3: return PTE_INDEX(virt, 21); + case 4: return PTE_INDEX(virt, 12); + default: return 0; + } + } else { + switch (level) { + case 0: return PTE_INDEX(virt, 39); + case 1: return PTE_INDEX(virt, 30); + case 2: return PTE_INDEX(virt, 21); + case 3: return PTE_INDEX(virt, 12); + default: return 0; + } + } + return 0; +} + +int64_t* __paging_next_level_noalloc(std::uint64_t* table, std::uint16_t idx) { + if (!(table[idx] & PTE_PRESENT)) + return (int64_t*) -1; + return (int64_t*) ((table[idx] & LVL_PG_MASK) + etc::hhdm()); +} + +std::int64_t __memory_paging_getphys(std::uint64_t* table, std::uint64_t virt, int level) { + if (!table && (std::int64_t) table == -1) + return -1; + int max_level = bootloader::bootloader->is_5_level_paging() ? 4 : 3; + if (max_level == level) { + return (table[level_to_index(virt, level)] & PTE_PRESENT) ? table[level_to_index(virt, level)] & LVL_PG_MASK : -1; + } else + return __memory_paging_getphys((std::uint64_t*) __paging_next_level_noalloc(table, level_to_index(virt, level)), virt, level + 1); + return -1; +} + +uint64_t* x86_64_paging_next_level(std::uint64_t* table, std::uint16_t idx, std::uint64_t flags) { + if (!(table[idx] & PTE_PRESENT)) + table[idx] = pmm::freelist::alloc_4k() | flags; + return (uint64_t*) ((table[idx] & LVL_PG_MASK) + etc::hhdm()); +} + +std::uint64_t convert_flags(std::uint64_t flags) { + std::uint64_t result = 0; + if (flags & PAGING_NC) + result |= PTE_MMIO; + if (flags & PAGING_PRESENT) + result |= PTE_PRESENT; + if (flags & PAGING_RW) + result |= PTE_RW; + if (flags & PAGING_USER) + result |= PTE_USER; + if (flags & PAGING_WC) + result |= PTE_WC; + return result; +} + +void x86_64_map_page(std::uintptr_t root, std::uintptr_t phys, std::uintptr_t virt, std::uint32_t flags) { + std::uint64_t* cr30 = (std::uint64_t*) (root + etc::hhdm()); + std::uint64_t new_flags = PTE_PRESENT | PTE_RW; + if (bootloader::bootloader->is_5_level_paging()) { + if (PTE_INDEX(virt, 48) < 256) + new_flags |= PTE_USER; + uint64_t* pml4 = x86_64_paging_next_level(cr30, PTE_INDEX(virt, 48), new_flags); + uint64_t* pml3 = x86_64_paging_next_level(pml4, PTE_INDEX(virt, 39), new_flags); + uint64_t* pml2 = x86_64_paging_next_level(pml3, PTE_INDEX(virt, 30), new_flags); + uint64_t* pml = x86_64_paging_next_level(pml2, PTE_INDEX(virt, 21), new_flags); + pml[PTE_INDEX(virt, 12)] = phys | flags; + } else { + if (PTE_INDEX(virt, 39) < 256) + new_flags |= PTE_USER; + uint64_t* pml3 = x86_64_paging_next_level(cr30, PTE_INDEX(virt, 39), new_flags); + uint64_t* pml2 = x86_64_paging_next_level(pml3, PTE_INDEX(virt, 30), new_flags); + uint64_t* pml = x86_64_paging_next_level(pml2, PTE_INDEX(virt, 21), new_flags); + pml[PTE_INDEX(virt, 12)] = phys | flags; + } +} + + +namespace arch { + [[gnu::weak]] void enable_paging(std::uintptr_t root) { + asm volatile("mov %0, %%cr3" : : "r"(root) : "memory"); + } + + [[gnu::weak]] void map_page(std::uintptr_t root, std::uint64_t phys, std::uintptr_t virt, int flags) { + x86_64_map_page(root,phys,virt,convert_flags(flags)); + } + + [[gnu::weak]] std::uint64_t get_phys_from_page(std::uintptr_t root, std::uintptr_t virt) { + return __memory_paging_getphys((std::uint64_t*)(root + etc::hhdm()),virt,0); + } + + [[gnu::weak]] void destroy_root(std::uintptr_t root, int level) { + std::uint64_t* table = (std::uint64_t*) (root + etc::hhdm()); + if (bootloader::bootloader->is_5_level_paging()) { + if (level != 4) { + if (level == 0) { + for (int i = 0; i < 256; i++) { + if (table[i] & PTE_PRESENT) { + destroy_root(table[i] & PTE_MASK_VALUE, level + 1); + } + } + } else { + for (int i = 0; i < 512; i++) { + if (table[i] & PTE_PRESENT) { + destroy_root(table[i] & PTE_MASK_VALUE, level + 1); + } + } + } + } + + if (level != 0) + pmm::freelist::free(root); + } else { + if (level != 3) { + if (level == 0) { + for (int i = 0; i < 256; i++) { + if (table[i] & PTE_PRESENT) { + destroy_root(table[i] & PTE_MASK_VALUE, level + 1); + } + } + } else { + for (int i = 0; i < 512; i++) { + if (table[i] & PTE_PRESENT) { + destroy_root(table[i] & PTE_MASK_VALUE, level + 1); + } + } + } + } + + if (level != 0) + pmm::freelist::free(root); + } + } + + [[gnu::weak]] void copy_higher_half(std::uintptr_t root, std::uintptr_t src_root) { + std::uint64_t* virt_rootcr3 = (std::uint64_t*) (root + etc::hhdm()); + std::uint64_t* virt_srccr3 = (std::uint64_t*) (src_root + etc::hhdm()); + for (int i = 255; i < 512; i++) { + virt_rootcr3[i] = virt_srccr3[i]; + } + } +};
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