/* set up page tables for kernel */
void init_page(void) {
CR0 cr0;
CR3 cr3;
PDE *pdir = (PDE *)va_to_pa(kpdir);
PTE *ptable = (PTE *)va_to_pa(kptable);
uint32_t pdir_idx;
/* make all PDEs invalid */
memset(pdir, 0, NR_PDE * sizeof(PDE));
/* fill PDEs */
for (pdir_idx = 0; pdir_idx < PHY_MEM / PT_SIZE; pdir_idx ++) {
pdir[pdir_idx].val = make_pde(ptable);
pdir[pdir_idx + KOFFSET / PT_SIZE].val = make_pde(ptable);
ptable += NR_PTE;
}
/* fill PTEs */
/* We use inline assembly here to fill PTEs for efficiency.
* If you do not understand it, refer to the C code below.
*/
asm volatile ("std;\
1: stosl;\
subl %0, %%eax;\
jge 1b;\
cld" : :
"i"(PAGE_SIZE), "a"((PHY_MEM - PAGE_SIZE) | 0x7), "D"(ptable - 1));
/*
===== referenced code for the inline assembly above =====
uint32_t pframe_addr = PHY_MEM - PAGE_SIZE;
ptable --;
// fill PTEs reversely
for (; pframe_addr >= 0; pframe_addr -= PAGE_SIZE) {
ptable->val = make_pte(pframe_addr);
ptable --;
}
*/
/* make CR3 to be the entry of page directory */
cr3.val = 0;
cr3.page_directory_base = ((uint32_t)pdir) >> 12;
write_cr3(cr3.val);
/* set PG bit in CR0 to enable paging */
cr0.val = read_cr0();
cr0.paging = 1;
write_cr0(cr0.val);
}
void map_page(uint32_t *page_dir, uint32_t virt_page_num, uint32_t phy_page_num,
bool global, bool user, bool read_write)
{
uint16_t pd_idx = PD_IDX(virt_page_num),
pt_idx = PT_IDX(virt_page_num);
uint32_t *page_table;
if(!(page_dir[pd_idx] & 0x1)) {
uint32_t pt_page_num = alloc_phy_page(0, 1023);
map_kernel_page(pt_page_num, pt_page_num, true, false, true);
memset((void *)(pt_page_num << 12), 0, 4096);
page_dir[pd_idx] = make_pde(pt_page_num, user, read_write);
}
page_table = (uint32_t *)(page_dir[pd_idx] & 0xfffff000);
page_table[pt_idx] = make_pte(phy_page_num, global, user, read_write);
++phy_mem_rc[phy_page_num];
__asm__ volatile(
".intel_syntax noprefix;"
"mov eax, cr3;"
"mov cr3, eax;"
".att_syntax;"
:::"eax"
);
}
/* Build a page table for the kernel */
void
init_page(void) {
CR0 cr0;
CR3 cr3;
PDE *pdir = (PDE *)va_to_pa(kpdir);
PTE *ptable = (PTE *)va_to_pa(kptable);
uint32_t pdir_idx, ptable_idx, pframe_idx;
for (pdir_idx = 0; pdir_idx < NR_PDE; pdir_idx ++) {
make_invalid_pde(&pdir[pdir_idx]);
}
pframe_idx = 0;
for (pdir_idx = 0; pdir_idx < PHY_MEM / PD_SIZE; pdir_idx ++) {
make_pde(&pdir[pdir_idx], ptable);
make_pde(&pdir[pdir_idx + KOFFSET / PD_SIZE], ptable);
for (ptable_idx = 0; ptable_idx < NR_PTE; ptable_idx ++) {
make_pte(ptable, (void*)(pframe_idx << 12));
pframe_idx ++;
ptable ++;
}
}
/* make CR3 to be the entry of page directory */
cr3.val = 0;
cr3.page_directory_base = ((uint32_t)pdir) >> 12;
write_cr3(&cr3);
/* set PG bit in CR0 to enable paging */
cr0.val = read_cr0();
cr0.paging = 1;
write_cr0(&cr0);
/* Now we can access global variables!
* Store CR3 in the global variable for future use. */
kcr3.val = cr3.val;
}
void create_video_mapping() {
/* TODO: create an identical mapping from virtual memory area
* [0xa0000, 0xa0000 + SCR_SIZE) to physical memory area
* [0xa0000, 0xa0000 + SCR_SIZE) for user program. You may define
* some page tables to create this mapping.
*/
PDE *pdir = (PDE *)get_updir();
PTE *ptable = (PTE *)va_to_pa(vdtable);
// ptable += (SCR_SIZE / PAGE_SIZE + 1) * PAGE_SIZE;
pdir->val = make_pde(vdtable);
// pdir[0 + KOFFSET / PT_SIZE].val = make_pde(vdtable);
// ptable --;
uint32_t pframe_addr = VMEM_ADDR;
int i=0;
for(; i<=0xf; i++) {
ptable[i+0xa0].val = make_pte(pframe_addr);
pframe_addr += PAGE_SIZE;
}
// panic("please implement me");
}
