diff options
| -rw-r--r-- | kernel/arch/i386/mmu.c | 62 |
1 files changed, 41 insertions, 21 deletions
diff --git a/kernel/arch/i386/mmu.c b/kernel/arch/i386/mmu.c index 4561675..ff35766 100644 --- a/kernel/arch/i386/mmu.c +++ b/kernel/arch/i386/mmu.c @@ -1,6 +1,7 @@ #include <assert.h> #include <ksbrk.h> #include <log.h> +#include <math.h> #include <mmu.h> #define INDEX_FROM_BIT(a) (a / (32)) @@ -15,8 +16,9 @@ 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}; +uint64_t num_of_frames; +uint32_t *frames; +uint64_t available_memory_kb; uint32_t num_allocated_frames = 0; #define KERNEL_START 0xc0000000 @@ -147,7 +149,6 @@ uint32_t first_free_frame(void) { 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)); @@ -359,7 +360,6 @@ void *allocate_frame(Page *page, int rw, int is_kernel) { 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; @@ -380,7 +380,6 @@ void mmu_free_address_range(void *ptr, size_t length) { 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; @@ -430,8 +429,7 @@ void *virtual_to_physical(void *address, PageDirectory *directory) { } extern uint32_t inital_esp; -void -move_stack(uint32_t new_stack_address, uint32_t size) { +void move_stack(uint32_t new_stack_address, uint32_t size) { mmu_allocate_region((void *)(new_stack_address - size), size, MMU_FLAG_KERNEL, NULL); @@ -516,13 +514,23 @@ void enable_paging(void) { "mov %eax, %cr0\n"); } -extern uint32_t boot_page_directory; -extern uint32_t boot_page_table1; +void create_table(int table_index) { + if (kernel_directory->tables[table_index]) + return; + uint32_t physical; + kernel_directory->tables[table_index] = (PageTable *)0xDEADBEEF; + kernel_directory->tables[table_index] = + (PageTable *)ksbrk_physical(sizeof(PageTable), (void **)&physical); + memset(kernel_directory->tables[table_index], 0, sizeof(PageTable)); + kernel_directory->physical_tables[table_index] = (uint32_t)physical | 0x3; +} -void paging_init(void) { +void paging_init(uint64_t memsize) { uint32_t *cr3; asm volatile("mov %%cr3, %0" : "=r"(cr3)); uint32_t *virtual = (uint32_t *)((uint32_t)cr3 + 0xC0000000); + frames = ksbrk(1024 * sizeof(uint32_t)); + num_of_frames = 1024 * 32; kernel_directory = &real_kernel_directory; kernel_directory->physical_address = (uint32_t)cr3; @@ -549,21 +557,33 @@ void paging_init(void) { } switch_page_directory(kernel_directory); + // Make null dereferences crash. get_page(NULL, kernel_directory, PAGE_ALLOCATE, 0)->present = 0; + for (int i = 0; i < 16; i++) + create_table(770 + i); kernel_directory = clone_directory(kernel_directory); - // Make null dereferences crash. switch_page_directory(kernel_directory); 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, 0x80000); + + uint64_t buffer_size = (memsize / 32) * sizeof(uint32_t); + // TODO: Very hacky solution since we have to memcpy the old allocation. This + // places a strict requierment on how much RAM the system can have(altough it + // is very small). Ideally the number of frames required would be dynamically + // calculated. + assert(buffer_size >= 1024 * sizeof(uint32_t)); + + // TODO Do this better + // NOTE: + // There are some addresses that point to devices rather than RAM. + // Therefore we need frames for these to exist + uint64_t min_buffer_required = 0xFD000 + 0x100000; + buffer_size = max(min_buffer_required, buffer_size); + + available_memory_kb = memsize; + num_of_frames = available_memory_kb / 4; + uint32_t *new_frames = ksbrk(buffer_size); + memcpy(new_frames, frames, 1024 * sizeof(uint32_t)); + frames = new_frames; } |