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-rw-r--r--kernel/l0/paging.c298
1 files changed, 0 insertions, 298 deletions
diff --git a/kernel/l0/paging.c b/kernel/l0/paging.c
deleted file mode 100644
index 683abe6..0000000
--- a/kernel/l0/paging.c
+++ /dev/null
@@ -1,298 +0,0 @@
-#include <paging.h>
-#include <frame.h>
-#include <idt.h>
-#include <dbglog.h>
-#include <region.h>
-#include <mutex.h>
-#include <thread.h>
-#include <kmalloc.h>
-
-#define PAGE_OF_ADDR(x) (((size_t)x >> PAGE_SHIFT) % N_PAGES_IN_PT)
-#define PT_OF_ADDR(x) ((size_t)x >> (PAGE_SHIFT + PT_SHIFT))
-
-#define PTE_PRESENT (1<<0)
-#define PTE_RW (1<<1)
-#define PTE_USER (1<<2)
-#define PTE_WRITE_THROUGH (1<<3)
-#define PTE_DISABLE_CACHE (1<<4)
-#define PTE_ACCESSED (1<<5)
-#define PTE_DIRTY (1<<6) // only PTE
-#define PTE_SIZE_4M (1<<7) // only PDE
-#define PTE_GLOBAL (1<<8) // only PTE
-#define PTE_FRAME_SHIFT 12
-
-typedef struct page_table {
- uint32_t page[1024];
-} pagetable_t;
-
-struct page_directory {
- uint32_t phys_addr; // physical address of page directory
- // to modify a page directory, we first map it
- // then we can use mirroring to edit it
- // (the last 4M of the address space are mapped to the PD itself)
-
- mutex_t mutex;
-};
-
-
-// access kernel page directory page defined in loader.s
-// (this is a correct higher-half address)
-extern pagetable_t kernel_pd;
-
-// pre-allocate a page table so that we can map the first 4M of kernel memory
-static pagetable_t __attribute__((aligned(PAGE_SIZE))) kernel_pt0;
-
-extern char kernel_stack_protector;
-
-static pagedir_t kernel_pd_d;
-
-#define current_pt ((pagetable_t*)PD_MIRROR_ADDR)
-#define current_pd ((pagetable_t*)(PD_MIRROR_ADDR + (N_PAGES_IN_PT-1)*PAGE_SIZE))
-
-void page_fault_handler(registers_t *regs) {
- void* vaddr;
- asm volatile("movl %%cr2, %0":"=r"(vaddr));
-
- if ((size_t)vaddr >= K_HIGHHALF_ADDR) {
- uint32_t pt = PT_OF_ADDR(vaddr);
-
- if (current_pd != &kernel_pd && current_pd->page[pt] != kernel_pd.page[pt]) {
- current_pd->page[pt] = kernel_pd.page[pt];
- invlpg(&current_pt[pt]);
- return;
- }
- if (regs->eflags & EFLAGS_IF) asm volatile("sti"); // from now on we are preemptible
-
- if (vaddr >= (void*)&kernel_stack_protector && vaddr < (void*)&kernel_stack_protector + PAGE_SIZE) {
- dbg_printf("Kernel stack overflow at 0x%p\n", vaddr);
- PANIC("Kernel stack overflow.");
- }
-
- if ((size_t)vaddr >= PD_MIRROR_ADDR) {
- dbg_printf("Fault on access to mirrorred PD at 0x%p\n", vaddr);
- dbg_print_region_info();
- PANIC("Unhandled kernel space page fault");
- }
-
- region_info_t *i = find_region(vaddr);
- if (i == 0) {
- dbg_printf("Kernel pagefault in non-existing region at 0x%p\n", vaddr);
- dbg_dump_registers(regs);
- PANIC("Unhandled kernel space page fault");
- }
- if (i->pf == 0) {
- dbg_printf("Kernel pagefault in region with no handler at 0x%p\n", vaddr);
- dbg_dump_registers(regs);
- dbg_print_region_info();
- PANIC("Unhandled kernel space page fault");
- }
- i->pf(get_current_pagedir(), i, vaddr);
- } else {
- if (regs->eflags & EFLAGS_IF) asm volatile("sti"); // userspace PF handlers should always be preemptible
-
- dbg_printf("Userspace page fault at 0x%p\n", vaddr);
- PANIC("Unhandled userspace page fault");
- // not handled yet
- // TODO
- }
-}
-
-void paging_setup(void* kernel_data_end) {
- size_t n_kernel_pages =
- PAGE_ALIGN_UP((size_t)kernel_data_end - K_HIGHHALF_ADDR)/PAGE_SIZE;
-
- ASSERT(n_kernel_pages <= 1024); // we use less than 4M for kernel
-
- // setup kernel_pd_d structure
- kernel_pd_d.phys_addr = (size_t)&kernel_pd - K_HIGHHALF_ADDR;
- kernel_pd_d.mutex = MUTEX_UNLOCKED;
-
- // setup kernel_pt0
- ASSERT(PAGE_OF_ADDR(K_HIGHHALF_ADDR) == 0); // kernel is 4M-aligned
- ASSERT(FIRST_KERNEL_PT == 768);
- for (size_t i = 0; i < n_kernel_pages; i++) {
- if ((i * PAGE_SIZE) + K_HIGHHALF_ADDR == (size_t)&kernel_stack_protector) {
- kernel_pt0.page[i] = 0; // don't map kernel stack protector page
- frame_free(i, 1);
- } else {
- kernel_pt0.page[i] = (i << PTE_FRAME_SHIFT) | PTE_PRESENT | PTE_RW | PTE_GLOBAL;
- }
- }
- for (size_t i = n_kernel_pages; i < 1024; i++){
- kernel_pt0.page[i] = 0;
- }
-
- // replace 4M mapping by kernel_pt0
- kernel_pd.page[FIRST_KERNEL_PT] =
- (((size_t)&kernel_pt0 - K_HIGHHALF_ADDR) & PAGE_MASK) | PTE_PRESENT | PTE_RW;
- // set up mirroring
- kernel_pd.page[N_PAGES_IN_PT-1] =
- (((size_t)&kernel_pd - K_HIGHHALF_ADDR) & PAGE_MASK) | PTE_PRESENT | PTE_RW;
-
- invlpg((void*)K_HIGHHALF_ADDR);
-
- // paging already enabled in loader, nothing to do.
-
- // disable 4M pages (remove PSE bit in CR4)
- uint32_t cr4;
- asm volatile("movl %%cr4, %0": "=r"(cr4));
- cr4 &= ~0x00000010;
- asm volatile("movl %0, %%cr4":: "r"(cr4));
-
- idt_set_ex_handler(EX_PAGE_FAULT, page_fault_handler);
-}
-
-pagedir_t *get_current_pagedir() {
- if (current_thread == 0) return &kernel_pd_d;
- return current_thread->current_pd_d;
-}
-
-pagedir_t *get_kernel_pagedir() {
- return &kernel_pd_d;
-}
-
-void switch_pagedir(pagedir_t *pd) {
- asm volatile("movl %0, %%cr3":: "r"(pd->phys_addr));
- if (current_thread != 0) current_thread->current_pd_d = pd;
-}
-
-// ============================== //
-// Mapping and unmapping of pages //
-// ============================== //
-
-uint32_t pd_get_frame(void* vaddr) {
- uint32_t pt = PT_OF_ADDR(vaddr);
- uint32_t page = PAGE_OF_ADDR(vaddr);
-
- pagetable_t *pd = ((size_t)vaddr >= K_HIGHHALF_ADDR ? &kernel_pd : current_pd);
-
- if (!pd->page[pt] & PTE_PRESENT) return 0;
- if (!current_pt[pt].page[page] & PTE_PRESENT) return 0;
- return current_pt[pt].page[page] >> PTE_FRAME_SHIFT;
-}
-
-int pd_map_page(void* vaddr, uint32_t frame_id, bool rw) {
- uint32_t pt = PT_OF_ADDR(vaddr);
- uint32_t page = PAGE_OF_ADDR(vaddr);
-
- ASSERT((size_t)vaddr < PD_MIRROR_ADDR);
-
- pagedir_t *pdd = ((size_t)vaddr >= K_HIGHHALF_ADDR || current_thread == 0
- ? &kernel_pd_d : current_thread->current_pd_d);
- pagetable_t *pd = ((size_t)vaddr >= K_HIGHHALF_ADDR ? &kernel_pd : current_pd);
- mutex_lock(&pdd->mutex);
-
- if (!pd->page[pt] & PTE_PRESENT) {
- uint32_t new_pt_frame = frame_alloc(1);
- if (new_pt_frame == 0) {
- mutex_unlock(&pdd->mutex);
- return 1; // OOM
- }
-
- current_pd->page[pt] = pd->page[pt] =
- (new_pt_frame << PTE_FRAME_SHIFT) | PTE_PRESENT | PTE_RW;
- invlpg(&current_pt[pt]);
- }
- current_pt[pt].page[page] =
- (frame_id << PTE_FRAME_SHIFT)
- | PTE_PRESENT
- | ((size_t)vaddr < K_HIGHHALF_ADDR ? PTE_USER : PTE_GLOBAL)
- | (rw ? PTE_RW : 0);
- invlpg(vaddr);
-
- mutex_unlock(&pdd->mutex);
- return 0;
-}
-
-void pd_unmap_page(void* vaddr) {
- uint32_t pt = PT_OF_ADDR(vaddr);
- uint32_t page = PAGE_OF_ADDR(vaddr);
-
- pagetable_t *pd = ((size_t)vaddr >= K_HIGHHALF_ADDR ? &kernel_pd : current_pd);
- // no need to lock the PD's mutex
-
- if (!pd->page[pt] & PTE_PRESENT) return;
- if (!current_pt[pt].page[page] & PTE_PRESENT) return;
-
- current_pt[pt].page[page] = 0;
- invlpg(vaddr);
-
- // If the page table is completely empty we might want to free
- // it, but we would actually lose a lot of time checking if
- // the PT is really empty (since we don't store the
- // number of used pages in each PT), so it's probably not worth it
-}
-
-// Creation and deletion of page directories
-
-pagedir_t *create_pagedir() {
- uint32_t pd_phys = 0;
- pagedir_t *pd = 0;
- void* temp = 0;
-
- pd_phys = frame_alloc(1);
- if (pd_phys == 0) goto error;
-
- pd = (pagedir_t*)kmalloc(sizeof(pagedir_t));
- if (pd == 0) goto error;
-
- temp = region_alloc(PAGE_SIZE, 0, 0);
- if (temp == 0) goto error;
-
- int error = pd_map_page(temp, pd_phys, true);
- if (error) goto error;
-
- pd->phys_addr = pd_phys * PAGE_SIZE;
- pd->mutex = MUTEX_UNLOCKED;
-
- // initialize PD with zeroes
- pagetable_t *pt = (pagetable_t*)temp;
- for (size_t i = 0; i < N_PAGES_IN_PT; i++) {
- pt->page[i] = 0;
- }
- // use kernel page tables
- for(size_t i = FIRST_KERNEL_PT; i < N_PAGES_IN_PT-1; i++) {
- pt->page[i] = kernel_pd.page[i];
- }
- // set up mirroring
- pt->page[N_PAGES_IN_PT-1] = pd->phys_addr | PTE_PRESENT | PTE_RW;
-
- region_free_unmap(temp);
-
- return pd;
-
- error:
- if (pd_phys != 0) frame_free(pd_phys, 1);
- if (pd != 0) kfree(pd);
- if (temp != 0) region_free(temp);
- return 0;
-}
-
-void delete_pagedir(pagedir_t *pd) {
- pagedir_t *restore_pd = get_current_pagedir();
- if (restore_pd == pd) restore_pd = &kernel_pd_d;
-
- // make a copy of page directory on the stack
- switch_pagedir(pd);
- pagetable_t backup;
- for (size_t i = 0; i < N_PAGES_IN_PT; i++) {
- backup.page[i] = current_pd->page[i];
- }
- switch_pagedir(restore_pd);
-
- // free the page tables
- for (size_t i = 0; i < FIRST_KERNEL_PT; i++) {
- if (backup.page[i] & PTE_PRESENT)
- frame_free(backup.page[i] >> PTE_FRAME_SHIFT, 1);
- }
- // free the page directory page
- uint32_t pd_phys = pd->phys_addr / PAGE_SIZE;
- ASSERT(pd_phys == (backup.page[N_PAGES_IN_PT-1] >> PTE_FRAME_SHIFT));
- frame_free(pd_phys, 1);
- // free the pagedir_t structure
- kfree(pd);
-
- return;
-}
-
-/* vim: set ts=4 sw=4 tw=0 noet :*/
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