diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/i386/boot.s | 128 | ||||
| -rw-r--r-- | arch/i386/mmu.c | 565 |
2 files changed, 0 insertions, 693 deletions
diff --git a/arch/i386/boot.s b/arch/i386/boot.s deleted file mode 100644 index 61bbfbb..0000000 --- a/arch/i386/boot.s +++ /dev/null @@ -1,128 +0,0 @@ -.set ALIGN, 1<<0 -.set MEMINFO, 1<<1 -.set VIDEO_MODE, 1<<2 -.set FLAGS, VIDEO_MODE|ALIGN | MEMINFO -.set MAGIC, 0x1BADB002 -.set CHECKSUM, -(MAGIC + FLAGS) - -#.section .multiboot -.align 16, 0 -.section .multiboot.data, "aw" - .align 4 - .long MAGIC - .long FLAGS - .long CHECKSUM - # unused(padding) - .long 0,0,0,0,0 - # Video mode - .long 0 # Linear graphics - .long 0 # Preferred width - .long 0 # Preferred height - .long 32 # Preferred pixel depth - -# Allocate the initial stack. -.section .bootstrap_stack, "aw", @nobits -stack_bottom: -.skip 16384 # 16 KiB -stack_top: - -.global boot_page_directory -.global boot_page_table1 -.section .bss, "aw", @nobits - .align 4096 -boot_page_directory: - .skip 4096 -boot_page_table1: - .skip 4096 - -.section .multiboot.text, "a" -.global _start -.extern _kernel_end -.type _start, @function -# Kernel entry -_start: - # edi contains the buffer we wish to modify - movl $(boot_page_table1 - 0xC0000000), %edi - - # for loop - movl $0, %esi - movl $1024, %ecx -1: - # esi = address - # If we are in kernel range jump to "label 2" - cmpl $_kernel_start, %esi - jl 2f - - # If we are past the kernel jump to the final stage - # "label 3" - cmpl $(_kernel_end - 0xC0000000), %esi - jge 3f - -2: - # Add permission to the pages - movl %esi, %edx - orl $0x003, %edx - movl %edx, (%edi) - - # Size of page is 4096 bytes. - addl $4096, %esi - # Size of entries in boot_page_table1 is 4 bytes. - addl $4, %edi - # Loop to the next entry if we haven't finished. - loop 1b - -3: - # Map the page table to both virtual addresses 0x00000000 and 0xC0000000. - movl $(boot_page_table1 - 0xC0000000 + 0x003), boot_page_directory - 0xC0000000 + 0 - movl $(boot_page_table1 - 0xC0000000 + 0x003), boot_page_directory - 0xC0000000 + 768 * 4 - - # Set cr3 to the address of the boot_page_directory. - movl $(boot_page_directory - 0xC0000000), %ecx - movl %ecx, %cr3 - - # Enable paging - movl %cr0, %ecx - orl $0x80000000, %ecx - movl %ecx, %cr0 - - # Jump to higher half with an absolute jump. - lea 4f, %ecx - jmp *%ecx - -.size _start, . - _start - -.section .text - -4: - # At this point, paging is fully set up and enabled. - - # Unmap the identity mapping as it is now unnecessary. - movl $0, boot_page_directory + 0 - - # Reload crc3 to force a TLB flush so the changes to take effect. - movl %cr3, %ecx - movl %ecx, %cr3 - - # Set up the stack. - mov $stack_top, %esp - - # Reset EFLAGS. - pushl $0 - popf - - pushl %esp - - /* Push the pointer to the Multiboot information structure. */ - pushl %ebx - /* Push the magic value. */ - pushl %eax - - mov $_kernel_end, %eax - pushl %eax - # Enter the high-level kernel. - call kernel_main - - # Infinite loop if the system has nothing more to do. - cli -1: hlt - jmp 1b diff --git a/arch/i386/mmu.c b/arch/i386/mmu.c deleted file mode 100644 index ccfe894..0000000 --- a/arch/i386/mmu.c +++ /dev/null @@ -1,565 +0,0 @@ -#include <assert.h> -#include <ksbrk.h> -#include <log.h> -#include <mmu.h> - -#define INDEX_FROM_BIT(a) (a / (32)) -#define OFFSET_FROM_BIT(a) (a % (32)) -#define PAGE_SIZE ((uintptr_t)0x1000) - -#define PAGE_ALLOCATE 1 -#define PAGE_NO_ALLOCATE 0 - -PageDirectory *kernel_directory; -PageDirectory real_kernel_directory; -PageDirectory *active_directory = 0; - -#define END_OF_MEMORY 0x8000000 * 15 -const uint32_t num_of_frames = END_OF_MEMORY / PAGE_SIZE; -uint32_t frames[END_OF_MEMORY / PAGE_SIZE] = {0}; -uint32_t num_allocated_frames = 0; - -#define KERNEL_START 0xc0000000 -extern uintptr_t data_end; - -void write_to_frame(uint32_t frame_address, uint8_t on); - -void *ksbrk(size_t s) { - uintptr_t rc = (uintptr_t)align_page((void *)data_end); - data_end += s; - data_end = (uintptr_t)align_page((void *)data_end); - - if (!get_active_pagedirectory()) { - // If there is no active pagedirectory we - // just assume that the memory is - // already mapped. - return (void *)rc; - } - // Determine whether we are approaching a unallocated table - int table_index = 1 + (rc / (1024 * 0x1000)); - if (!active_directory->tables[table_index]) { - uint32_t physical; - active_directory->tables[table_index] = (PageTable *)0xDEADBEEF; - active_directory->tables[table_index] = - (PageTable *)ksbrk_physical(sizeof(PageTable), (void **)&physical); - memset(active_directory->tables[table_index], 0, sizeof(PageTable)); - active_directory->physical_tables[table_index] = (uint32_t)physical | 0x3; - - kernel_directory->tables[table_index] = - active_directory->tables[table_index]; - kernel_directory->physical_tables[table_index] = - active_directory->physical_tables[table_index]; - return ksbrk(s); - } - mmu_allocate_shared_kernel_region((void *)rc, (data_end - (uintptr_t)rc)); - assert(((uintptr_t)rc % PAGE_SIZE) == 0); - memset((void *)rc, 0x00, s); - - return (void *)rc; -} - -void *ksbrk_physical(size_t s, void **physical) { - void *r = ksbrk(s); - if (physical) { - *physical = (void *)virtual_to_physical(r, 0); - } - return r; -} - -uint32_t mmu_get_number_of_allocated_frames(void) { - return num_allocated_frames; -} - -Page *get_page(void *ptr, PageDirectory *directory, int create_new_page, - int set_user) { - uintptr_t address = (uintptr_t)ptr; - if (!directory) - directory = get_active_pagedirectory(); - address /= 0x1000; - - uint32_t table_index = address / 1024; - if (!directory->tables[table_index]) { - if (!create_new_page) - return 0; - - uint32_t physical; - directory->tables[table_index] = - (PageTable *)ksbrk_physical(sizeof(PageTable), (void **)&physical); - memset(directory->tables[table_index], 0, sizeof(PageTable)); - directory->physical_tables[table_index] = - (uint32_t)physical | ((set_user) ? 0x7 : 0x3); - - if (!set_user) { - kernel_directory->tables[table_index] = directory->tables[table_index]; - kernel_directory->physical_tables[table_index] = - directory->physical_tables[table_index]; - } - } - Page *p = &directory->tables[table_index]->pages[address % 1024]; - if (create_new_page) { - p->present = 0; - } - return &directory->tables[table_index]->pages[address % 1024]; -} - -void mmu_free_pages(void *a, uint32_t n) { - for (; n > 0; n--) { - Page *p = get_page(a, NULL, PAGE_NO_ALLOCATE, 0); - p->present = 0; - write_to_frame(p->frame * 0x1000, 0); - a += 0x1000; - } -} - -void *next_page(void *ptr) { - uintptr_t a = (uintptr_t)ptr; - return (void *)(a + (PAGE_SIZE - ((uint32_t)a & (PAGE_SIZE - 1)))); -} - -void *align_page(void *a) { - if ((uintptr_t)a & (PAGE_SIZE - 1)) - return next_page(a); - - return a; -} - -void flush_tlb(void) { - asm volatile("\ - mov %cr3, %eax;\ - mov %eax, %cr3"); -} - -uint32_t first_free_frame(void) { - for (uint32_t i = 1; i < INDEX_FROM_BIT(num_of_frames); i++) { - if (frames[i] == 0xFFFFFFFF) - continue; - - for (uint32_t c = 0; c < 32; c++) - if (!(frames[i] & ((uint32_t)1 << c))) - return i * 32 + c; - } - - kprintf("ERROR Num frames: %x\n", mmu_get_number_of_allocated_frames()); - klog("No free frames, uh oh.", LOG_ERROR); - assert(0); - return 0; -} - -void write_to_frame(uint32_t frame_address, uint8_t on) { - uint32_t frame = frame_address / 0x1000; - assert(INDEX_FROM_BIT(frame) < sizeof(frames) / sizeof(frames[0])); - if (on) { - num_allocated_frames++; - frames[INDEX_FROM_BIT(frame)] |= ((uint32_t)0x1 << OFFSET_FROM_BIT(frame)); - return; - } - num_allocated_frames--; - frames[INDEX_FROM_BIT(frame)] &= ~((uint32_t)0x1 << OFFSET_FROM_BIT(frame)); -} - -PageDirectory *get_active_pagedirectory(void) { return active_directory; } - -PageTable *clone_table(uint32_t src_index, PageDirectory *src_directory, - uint32_t *physical_address) { - PageTable *new_table = - ksbrk_physical(sizeof(PageTable), (void **)physical_address); - PageTable *src = src_directory->tables[src_index]; - - // Copy all the pages - for (uint16_t i = 0; i < 1024; i++) { - if (!src->pages[i].present) { - new_table->pages[i].present = 0; - continue; - } - uint32_t frame_address = first_free_frame(); - write_to_frame(frame_address * 0x1000, 1); - new_table->pages[i].frame = frame_address; - - new_table->pages[i].present |= src->pages[i].present; - new_table->pages[i].rw |= src->pages[i].rw; - new_table->pages[i].user |= src->pages[i].user; - new_table->pages[i].accessed |= src->pages[i].accessed; - new_table->pages[i].dirty |= src->pages[i].dirty; - } - - // Now copy all of the data to the new table. This is done by creating a - // virutal pointer to this newly created tables physical frame so we can - // copy data to it. - for (uint32_t i = 0; i < 1024; i++) { - // Find a unused table - if (src_directory->tables[i]) - continue; - - // Link the table to the new table temporarily - src_directory->tables[i] = new_table; - src_directory->physical_tables[i] = *physical_address | 0x7; - PageDirectory *tmp = get_active_pagedirectory(); - switch_page_directory(src_directory); - - // For each page in the table copy all the data over. - for (uint32_t c = 0; c < 1024; c++) { - // Only copy pages that are used. - if (!src->pages[c].frame || !src->pages[c].present) - continue; - - uint32_t table_data_pointer = i << 22 | c << 12; - uint32_t src_data_pointer = src_index << 22 | c << 12; - memcpy((void *)table_data_pointer, (void *)src_data_pointer, 0x1000); - } - src_directory->tables[i] = 0; - src_directory->physical_tables[i] = 0; - switch_page_directory(tmp); - return new_table; - } - ASSERT_NOT_REACHED; - return 0; -} - -PageTable *copy_table(PageTable *src, uint32_t *physical_address) { - PageTable *new_table = - ksbrk_physical(sizeof(PageTable), (void **)physical_address); - - // copy all the pages - for (uint16_t i = 0; i < 1024; i++) { - if (!src->pages[i].present) { - new_table->pages[i].present = 0; - continue; - } - new_table->pages[i].frame = src->pages[i].frame; - new_table->pages[i].present = src->pages[i].present; - new_table->pages[i].rw = src->pages[i].rw; - new_table->pages[i].user = src->pages[i].user; - new_table->pages[i].accessed = src->pages[i].accessed; - new_table->pages[i].dirty = src->pages[i].dirty; - } - return new_table; -} - -PageDirectory *clone_directory(PageDirectory *original) { - if (!original) - original = get_active_pagedirectory(); - - uint32_t physical_address; - PageDirectory *new_directory = - ksbrk_physical(sizeof(PageDirectory), (void **)&physical_address); - uint32_t offset = - (uint32_t)new_directory->physical_tables - (uint32_t)new_directory; - new_directory->physical_address = physical_address + offset; - - for (int i = 0; i < 1024; i++) { - if (!original->tables[i]) { - new_directory->tables[i] = NULL; - new_directory->physical_tables[i] = (uint32_t)NULL; - continue; - } - - // Make sure to copy instead of cloning the stack. - if (i >= 635 && i <= 641) { - uint32_t physical; - new_directory->tables[i] = clone_table(i, original, &physical); - new_directory->physical_tables[i] = - physical | (original->physical_tables[i] & 0xFFF); - continue; - } - - // if (original->tables[i] == kernel_directory->tables[i]) { - if (i > 641) { - new_directory->tables[i] = kernel_directory->tables[i]; - new_directory->physical_tables[i] = kernel_directory->physical_tables[i]; - continue; - } - - uint32_t physical; - new_directory->tables[i] = clone_table(i, original, &physical); - new_directory->physical_tables[i] = - physical | (original->physical_tables[i] & 0xFFF); - } - - return new_directory; -} - -void mmu_allocate_shared_kernel_region(void *rc, size_t n) { - size_t num_pages = n / PAGE_SIZE; - for (size_t i = 0; i <= num_pages; i++) { - Page *p = get_page((void *)(rc + i * 0x1000), NULL, PAGE_NO_ALLOCATE, 0); - if (!p) { - kprintf("don't have: %x\n", rc + i * 0x1000); - p = get_page((void *)(rc + i * 0x1000), NULL, PAGE_ALLOCATE, 0); - } - if (!p->present || !p->frame) - allocate_frame(p, 0, 1); - } -} - -void mmu_remove_virtual_physical_address_mapping(void *ptr, size_t length) { - size_t num_pages = (uintptr_t)align_page((void *)length) / PAGE_SIZE; - for (size_t i = 0; i < num_pages; i++) { - Page *p = get_page(ptr + (i * PAGE_SIZE), NULL, PAGE_NO_ALLOCATE, 0); - if (!p) - return; - p->frame = 0; - p->present = 0; - } -} - -void *mmu_find_unallocated_virtual_range(void *addr, size_t length) { - addr = align_page(addr); - // Check if the pages already exist - for (size_t i = 0; i < length; i += 0x1000) { - if (get_page(addr + i, NULL, PAGE_NO_ALLOCATE, 0)) { - // Page already exists - return mmu_find_unallocated_virtual_range(addr + 0x1000, length); - } - } - return addr; -} - -int mmu_allocate_region(void *ptr, size_t n, mmu_flags flags, - PageDirectory *pd) { - pd = (pd) ? pd : get_active_pagedirectory(); - size_t num_pages = n / 0x1000; - for (size_t i = 0; i <= num_pages; i++) { - Page *p = get_page((void *)(ptr + i * 0x1000), pd, PAGE_ALLOCATE, 1); - assert(p); - int rw = (flags & MMU_FLAG_RW); - int kernel = (flags & MMU_FLAG_KERNEL); - if (!allocate_frame(p, rw, kernel)) { - klog("MMU: Frame allocation failed", LOG_WARN); - return 0; - } - } - return 1; -} - -void *mmu_map_frames(void *const ptr, size_t s) { - void *const r = mmu_find_unallocated_virtual_range((void *)0xEF000000, s); - kprintf("r: %x\n", r); - size_t num_pages = s / 0x1000; - for (size_t i = 0; i <= num_pages; i++) { - Page *p = get_page((void *)(r + i * 0x1000), NULL, PAGE_ALLOCATE, 1); - assert(p); - int rw = 1; - int is_kernel = 1; - p->present = 1; - p->rw = rw; - p->user = !is_kernel; - p->frame = (uintptr_t)(ptr + i * 0x1000) / 0x1000; - write_to_frame((uintptr_t)ptr + i * 0x1000, 1); - } - flush_tlb(); - return r; -} - -void *allocate_frame(Page *page, int rw, int is_kernel) { - if (page->present) { - dump_backtrace(5); - klog("Page is already set", 1); - for (;;) - ; - return 0; - } - uint32_t frame_address = first_free_frame(); - assert(frame_address < sizeof(frames) / sizeof(frames[0])); - write_to_frame(frame_address * 0x1000, 1); - - page->present = 1; - page->rw = rw; - page->user = !is_kernel; - page->frame = frame_address; - return (void *)(frame_address * 0x1000); -} - -void mmu_free_address_range(void *ptr, size_t length) { - size_t num_pages = (size_t)align_page((void *)length) / PAGE_SIZE; - for (size_t i = 0; i < num_pages; i++, ptr += PAGE_SIZE) { - Page *page = get_page(ptr, NULL, PAGE_NO_ALLOCATE, 0); - if (!page) - continue; - if (!page->present) - continue; - if (!page->frame) - continue; - // Sanity check that none of the frames are invalid - assert(page->frame < sizeof(frames) / sizeof(frames[0])); - write_to_frame(((uint32_t)page->frame) * 0x1000, 0); - page->present = 0; - page->rw = 0; - page->user = 0; - page->frame = 0; - } -} - -void mmu_map_directories(void *dst, PageDirectory *d, void *src, - PageDirectory *s, size_t length) { - d = (!d) ? get_active_pagedirectory() : d; - s = (!s) ? get_active_pagedirectory() : s; - size_t num_pages = (uint32_t)align_page((void *)length) / 0x1000; - for (size_t i = 0; i < num_pages; i++, dst += 0x1000, src += 0x1000) { - Page *p = get_page(dst, d, PAGE_ALLOCATE, 1); - p->present = 1; - p->rw = 1; - p->user = 1; - void *physical = virtual_to_physical(src, s); - p->frame = (uint32_t)physical / PAGE_SIZE; - } - flush_tlb(); -} - -void mmu_map_physical(void *dst, PageDirectory *d, void *physical, - size_t length) { - d = (!d) ? get_active_pagedirectory() : d; - size_t num_pages = (uint32_t)align_page((void *)length) / 0x1000; - for (size_t i = 0; i < num_pages; i++, dst += 0x1000, physical += 0x1000) { - Page *p = get_page(dst, d, PAGE_ALLOCATE, 1); - p->present = 1; - p->rw = 1; - p->user = 1; - p->frame = (uintptr_t)physical / PAGE_SIZE; - write_to_frame((uintptr_t)physical, 1); - } - flush_tlb(); -} - -void *virtual_to_physical(void *address, PageDirectory *directory) { - if (0 == directory) - directory = get_active_pagedirectory(); - return (void *)((get_page((void *)address, directory, PAGE_NO_ALLOCATE, 0) - ->frame * - 0x1000) + - (((uintptr_t)address) & 0xFFF)); -} - -extern uint32_t inital_esp; -void __attribute__((optimize("O0"))) -move_stack(uint32_t new_stack_address, uint32_t size) { - mmu_allocate_region((void *)(new_stack_address - size), size, - MMU_FLAG_KERNEL, NULL); - - uint32_t old_stack_pointer, old_base_pointer; - - register uint32_t eax asm("eax"); - asm volatile("mov %esp, %eax"); - old_stack_pointer = eax; - asm volatile("mov %ebp, %eax"); - old_base_pointer = eax; - - uint32_t new_stack_pointer = - old_stack_pointer + ((uint32_t)new_stack_address - inital_esp); - uint32_t new_base_pointer = - old_base_pointer + ((uint32_t)new_stack_address - inital_esp); - - // Copy the stack - memcpy((void *)new_stack_pointer, (void *)old_stack_pointer, - inital_esp - old_stack_pointer); - for (uint32_t i = (uint32_t)new_stack_address; i > new_stack_address - size; - i -= 4) { - uint32_t tmp = *(uint32_t *)i; - if (old_stack_pointer < tmp && tmp < inital_esp) { - tmp = tmp + (new_stack_address - inital_esp); - uint32_t *tmp2 = (uint32_t *)i; - *tmp2 = tmp; - } - } - - inital_esp = new_stack_pointer; - // Actually change the stack - eax = new_stack_pointer; - asm volatile("mov %eax, %esp"); - eax = new_base_pointer; - asm volatile("mov %eax, %ebp"); -} - -// C strings have a unknown length so it does not makes sense to check -// for a size on the pointer. Instead we check whether the page it -// resides in is accessible to the user. -void *is_valid_user_c_string(const char *ptr, size_t *size) { - void *r = (void *)ptr; - size_t s = 0; - for (;;) { - void *page = (void *)((uintptr_t)ptr & (uintptr_t)(~(PAGE_SIZE - 1))); - if (!is_valid_userpointer(page, PAGE_SIZE)) - return NULL; - for (; (uintptr_t)ptr & (PAGE_SIZE - 1); ptr++, s++) - if (!*ptr) { - if (size) - *size = s; - return r; - } - } -} - -void *is_valid_userpointer(const void *ptr, size_t s) { - uintptr_t t = (uintptr_t)ptr; - size_t num_pages = (uintptr_t)align_page((void *)s) / 0x1000; - for (size_t i = 0; i < num_pages; i++, t += 0x1000) { - Page *page = get_page((void *)t, NULL, PAGE_NO_ALLOCATE, 0); - if (!page) - return NULL; - if (!page->present) - return NULL; - if (!page->user) - return NULL; - } - return (void *)ptr; -} - -void switch_page_directory(PageDirectory *directory) { - active_directory = directory; - asm("mov %0, %%cr3" ::"r"(directory->physical_address)); -} - -void enable_paging(void) { - asm("mov %cr0, %eax\n" - "or 0b10000000000000000000000000000000, %eax\n" - "mov %eax, %cr0\n"); -} - -extern uint32_t boot_page_directory; -extern uint32_t boot_page_table1; - -void paging_init(void) { - uint32_t *cr3; - asm volatile("mov %%cr3, %0" : "=r"(cr3)); - uint32_t *virtual = (uint32_t *)((uint32_t)cr3 + 0xC0000000); - - kernel_directory = &real_kernel_directory; - kernel_directory->physical_address = (uint32_t)cr3; - for (uint32_t i = 0; i < 1024; i++) { - kernel_directory->physical_tables[i] = virtual[i]; - - if (!kernel_directory->physical_tables[i]) { - kernel_directory->tables[i] = NULL; - continue; - } - - kernel_directory->tables[i] = - (PageTable *)(0xC0000000 + (virtual[i] & ~(0xFFF))); - - // Loop through the pages in the table - PageTable *table = kernel_directory->tables[i]; - for (size_t j = 0; j < 1024; j++) { - if (!table->pages[j].present) - continue; - // Add the frame to our bitmap to ensure it does not get used by - // another newly created page. - write_to_frame(table->pages[j].frame * 0x1000, 1); - } - } - - switch_page_directory(kernel_directory); - kernel_directory = clone_directory(kernel_directory); - - // Make null dereferences crash. - switch_page_directory(kernel_directory); - get_page(NULL, kernel_directory, PAGE_ALLOCATE, 0)->present = 0; - switch_page_directory(clone_directory(kernel_directory)); - // FIXME: Really hacky solution. Since page table creation needs to - // allocate memory but memory allocation requires page table creation - // they depend on eachother. The bad/current solution is just to - // allocate a bunch of tables so the memory allocator has enough. - for (uintptr_t i = 0; i < 140; i++) - allocate_frame( - get_page((void *)((0x302 + i) * 0x1000 * 1024), NULL, PAGE_ALLOCATE, 0), - 1, 1); - move_stack(0xA0000000, 0xC00000); -} |