| #include "vm.h" |
| #include "libcflat.h" |
| #include "vmalloc.h" |
| #include "alloc_page.h" |
| |
| pteval_t *install_pte(pgd_t *cr3, |
| int pte_level, |
| void *virt, |
| pteval_t pte, |
| pteval_t *pt_page) |
| { |
| int level; |
| pteval_t *pt = cr3; |
| unsigned offset; |
| |
| for (level = PAGE_LEVEL; level > pte_level; --level) { |
| offset = PGDIR_OFFSET((uintptr_t)virt, level); |
| if (!(pt[offset] & PT_PRESENT_MASK)) { |
| pteval_t *new_pt = pt_page; |
| if (!new_pt) |
| new_pt = alloc_page(); |
| else |
| pt_page = 0; |
| memset(new_pt, 0, PAGE_SIZE); |
| pt[offset] = virt_to_phys(new_pt) | PT_PRESENT_MASK | PT_WRITABLE_MASK | PT_USER_MASK; |
| } |
| pt = phys_to_virt(pt[offset] & PT_ADDR_MASK); |
| } |
| offset = PGDIR_OFFSET((uintptr_t)virt, level); |
| pt[offset] = pte; |
| return &pt[offset]; |
| } |
| |
| /* |
| * Finds last PTE in the mapping of @virt that's at or above @lowest_level. The |
| * returned PTE isn't necessarily present, but its parent is. |
| */ |
| struct pte_search find_pte_level(pgd_t *cr3, void *virt, |
| int lowest_level) |
| { |
| pteval_t *pt = cr3, pte; |
| unsigned offset; |
| unsigned shift; |
| struct pte_search r; |
| |
| assert(lowest_level >= 1 && lowest_level <= PAGE_LEVEL); |
| |
| for (r.level = PAGE_LEVEL;; --r.level) { |
| shift = (r.level - 1) * PGDIR_WIDTH + 12; |
| offset = ((uintptr_t)virt >> shift) & PGDIR_MASK; |
| r.pte = &pt[offset]; |
| pte = *r.pte; |
| |
| if (!(pte & PT_PRESENT_MASK)) |
| return r; |
| |
| if ((r.level == 2 || r.level == 3) && (pte & PT_PAGE_SIZE_MASK)) |
| return r; |
| |
| if (r.level == lowest_level) |
| return r; |
| |
| pt = phys_to_virt(pte & 0xffffffffff000ull); |
| } |
| } |
| |
| /* |
| * Returns the leaf PTE in the mapping of @virt (i.e., 4K PTE or a present huge |
| * PTE). Returns NULL if no leaf PTE exists. |
| */ |
| pteval_t *get_pte(pgd_t *cr3, void *virt) |
| { |
| struct pte_search search; |
| |
| search = find_pte_level(cr3, virt, 1); |
| return found_leaf_pte(search) ? search.pte : NULL; |
| } |
| |
| /* |
| * Returns the PTE in the mapping of @virt at the given level @pte_level. |
| * Returns NULL if the PT at @pte_level isn't present (i.e., the mapping at |
| * @pte_level - 1 isn't present). |
| */ |
| pteval_t *get_pte_level(pgd_t *cr3, void *virt, int pte_level) |
| { |
| struct pte_search search; |
| |
| search = find_pte_level(cr3, virt, pte_level); |
| return search.level == pte_level ? search.pte : NULL; |
| } |
| |
| pteval_t *install_large_page(pgd_t *cr3, phys_addr_t phys, void *virt) |
| { |
| return install_pte(cr3, 2, virt, |
| phys | PT_PRESENT_MASK | PT_WRITABLE_MASK | PT_USER_MASK | PT_PAGE_SIZE_MASK, 0); |
| } |
| |
| pteval_t *install_page(pgd_t *cr3, phys_addr_t phys, void *virt) |
| { |
| return install_pte(cr3, 1, virt, phys | PT_PRESENT_MASK | PT_WRITABLE_MASK | PT_USER_MASK, 0); |
| } |
| |
| void install_pages(pgd_t *cr3, phys_addr_t phys, size_t len, void *virt) |
| { |
| phys_addr_t max = (u64)len + (u64)phys; |
| assert(phys % PAGE_SIZE == 0); |
| assert((uintptr_t) virt % PAGE_SIZE == 0); |
| assert(len % PAGE_SIZE == 0); |
| |
| while (phys + PAGE_SIZE <= max) { |
| install_page(cr3, phys, virt); |
| phys += PAGE_SIZE; |
| virt = (char *) virt + PAGE_SIZE; |
| } |
| } |
| |
| bool any_present_pages(pgd_t *cr3, void *virt, size_t len) |
| { |
| uintptr_t max = (uintptr_t) virt + len; |
| uintptr_t curr; |
| |
| for (curr = (uintptr_t) virt; curr < max; curr += PAGE_SIZE) { |
| pteval_t *ptep = get_pte(cr3, (void *) curr); |
| if (ptep && (*ptep & PT_PRESENT_MASK)) |
| return true; |
| } |
| return false; |
| } |
| |
| static void setup_mmu_range(pgd_t *cr3, phys_addr_t start, size_t len) |
| { |
| u64 max = (u64)len + (u64)start; |
| u64 phys = start; |
| |
| while (phys + LARGE_PAGE_SIZE <= max) { |
| install_large_page(cr3, phys, (void *)(ulong)phys); |
| phys += LARGE_PAGE_SIZE; |
| } |
| install_pages(cr3, phys, max - phys, (void *)(ulong)phys); |
| } |
| |
| void *setup_mmu(phys_addr_t end_of_memory) |
| { |
| pgd_t *cr3 = alloc_page(); |
| |
| memset(cr3, 0, PAGE_SIZE); |
| |
| #ifdef __x86_64__ |
| if (end_of_memory < (1ul << 32)) |
| end_of_memory = (1ul << 32); /* map mmio 1:1 */ |
| |
| setup_mmu_range(cr3, 0, end_of_memory); |
| #else |
| if (end_of_memory > (1ul << 31)) |
| end_of_memory = (1ul << 31); |
| |
| /* 0 - 2G memory, 2G-3G valloc area, 3G-4G mmio */ |
| setup_mmu_range(cr3, 0, end_of_memory); |
| setup_mmu_range(cr3, 3ul << 30, (1ul << 30)); |
| init_alloc_vpage((void*)(3ul << 30)); |
| #endif |
| |
| write_cr3(virt_to_phys(cr3)); |
| #ifndef __x86_64__ |
| write_cr4(X86_CR4_PSE); |
| #endif |
| write_cr0(X86_CR0_PG |X86_CR0_PE | X86_CR0_WP); |
| |
| printf("paging enabled\n"); |
| printf("cr0 = %lx\n", read_cr0()); |
| printf("cr3 = %lx\n", read_cr3()); |
| printf("cr4 = %lx\n", read_cr4()); |
| return cr3; |
| } |
| |
| phys_addr_t virt_to_pte_phys(pgd_t *cr3, void *mem) |
| { |
| return (*get_pte(cr3, mem) & PT_ADDR_MASK) + ((ulong)mem & (PAGE_SIZE - 1)); |
| } |
| |
| /* |
| * split_large_page: Split a 2M/1G large page into 512 smaller PTEs. |
| * @ptep : large page table entry to split |
| * @level : level of ptep (2 or 3) |
| */ |
| void split_large_page(unsigned long *ptep, int level) |
| { |
| unsigned long *new_pt; |
| unsigned long pa; |
| unsigned long pte; |
| unsigned long prototype; |
| int i; |
| |
| pte = *ptep; |
| assert(pte & PT_PRESENT_MASK); |
| assert(pte & PT_PAGE_SIZE_MASK); |
| assert(level == 2 || level == 3); |
| |
| new_pt = alloc_page(); |
| assert(new_pt); |
| |
| prototype = pte & ~PT_ADDR_MASK; |
| if (level == 2) |
| prototype &= ~PT_PAGE_SIZE_MASK; |
| |
| pa = pte & PT_ADDR_MASK; |
| for (i = 0; i < (1 << PGDIR_WIDTH); i++) { |
| new_pt[i] = prototype | pa; |
| pa += 1ul << PGDIR_BITS(level - 1); |
| } |
| |
| pte &= ~PT_PAGE_SIZE_MASK; |
| pte &= ~PT_ADDR_MASK; |
| pte |= virt_to_phys(new_pt); |
| |
| /* Modify the relevant paging-structure entry */ |
| *ptep = pte; |
| |
| /* |
| * Flush the TLB to eradicate stale mappings. |
| * |
| * Note: Removing specific TLB mappings is tricky because |
| * split_large_page() can be called to split the active code page |
| * backing the next set of instructions to be fetched and executed. |
| * Furthermore, Intel SDM volume 3 recommends to clear the present bit |
| * for the page being split, before invalidating any mappings. |
| * |
| * But clearing the mapping from the page table and removing it from the |
| * TLB (where it's not actually guaranteed to reside anyway) makes it |
| * impossible to continue fetching instructions! |
| */ |
| flush_tlb(); |
| } |
| |
| /* |
| * force_4k_page: Ensures that addr translate to a 4k page. |
| * |
| * This function uses split_large_page(), as needed, to ensure that target |
| * address, addr, translates to a 4k page. |
| * |
| * @addr: target address that should be mapped to a 4k page |
| */ |
| void force_4k_page(void *addr) |
| { |
| unsigned long *ptep; |
| unsigned long pte; |
| unsigned long *cr3 = current_page_table(); |
| |
| ptep = get_pte_level(cr3, addr, 3); |
| assert(ptep); |
| pte = *ptep; |
| assert(pte & PT_PRESENT_MASK); |
| if (pte & PT_PAGE_SIZE_MASK) |
| split_large_page(ptep, 3); |
| |
| ptep = get_pte_level(cr3, addr, 2); |
| assert(ptep); |
| pte = *ptep; |
| assert(pte & PT_PRESENT_MASK); |
| if (pte & PT_PAGE_SIZE_MASK) |
| split_large_page(ptep, 2); |
| } |