/*
* uint8_t* user_vidmap()
* Description: Maps video memory for a user process
* Inputs: none
* Return Value: A pointer to the newly mapped virtual memory
*/
uint8_t* user_vidmap()
{
// Set up PTE if necessary
uint32_t PT_index = get_PTE_offset(USER_VID);
if(PT[1][PT_index].present == 0)
{
PTE_t PTE_video;
PTE_video = PTE_default;
PTE_video.user_super = 1;
PTE_video.read_write = 1;
SET_PTE(PTE_video, VIDEO_MEM);
PT[1][PT_index] = PTE_video;
}
// Set up PDE if necessary
uint32_t PD_index = get_PDE_offset(USER_VID);
if(cur_PD[PD_index].present == 0)
{
PDE_t PDE_video;
PDE_video = PDE_default;
PDE_video.user_super = 1;
PDE_video.read_write = 1;
SET_PDE_4KB_PT(PDE_video, PT[1]);
cur_PD[PD_index] = PDE_video;
}
INVLPG(USER_VID);
return (uint8_t*)USER_VID;
}
/*
* void init_VIDEO_PT()
* Description: Sets up video memory mapping for kernel
* Inputs: none
* Return Value: none
*/
void init_VIDEO_PT()
{
// Fill the video page table with blank entries
PTE_default.present = 0;
PTE_default.read_write = 0;
PTE_default.user_super = 0;
PTE_default.write_through = 0;
PTE_default.cache_disabled = 0;
PTE_default.accessed = 0;
PTE_default.dirty = 0;
PTE_default.page_table_attribute = 0;
PTE_default.global = 0;
PTE_default.avail = 0;
PTE_default.page_base = 0;
int i, j;
for(i = 0; i < NUM_PT; i++)
{
for(j = 0; j < NUM_PTE; j++)
{
PT[i][j] = PTE_default;
}
}
// Set up the kernel video PTE
int offset = get_PTE_offset(VIDEO_MEM);
PTE_t PTE_video;
PTE_video = PTE_default;
PTE_video.global = 1;
PTE_video.read_write = 1;
SET_PTE(PTE_video, VIDEO_MEM);
PT[0][offset] = PTE_video;
}
void map_page(void *vaddr, unsigned long pfn, unsigned long flags) {
// Allocate page table if not already done
if ((GET_PDE(vaddr) & PT_PRESENT) == 0) {
unsigned long pdfn;
pdfn = alloc_pageframe('PTAB');
if (USERSPACE(vaddr)) {
SET_PDE(vaddr, PTOB(pdfn) | PT_PRESENT | PT_WRITABLE | PT_USER);
} else {
SET_PDE(vaddr, PTOB(pdfn) | PT_PRESENT | PT_WRITABLE);
}
memset(ptab + PDEIDX(vaddr) * PTES_PER_PAGE, 0, PAGESIZE);
register_page_table(pdfn);
}
// Map page frame into address space
SET_PTE(vaddr, PTOB(pfn) | flags);
}
void clear_dirty(void *vaddr) {
SET_PTE(vaddr, GET_PTE(vaddr) & ~PT_DIRTY);
invlpage(vaddr);
}
void unguard_page(void *vaddr) {
SET_PTE(vaddr, (GET_PTE(vaddr) & ~PT_GUARD) | PT_USER);
invlpage(vaddr);
}
void set_page_flags(void *vaddr, unsigned long flags) {
SET_PTE(vaddr, (GET_PTE(vaddr) & PT_PFNMASK) | flags);
invlpage(vaddr);
}
void unmap_page(void *vaddr) {
SET_PTE(vaddr, 0);
invlpage(vaddr);
}
void init_pdir() {
unsigned long i;
// Clear identity mapping of the first 4 MB made by the os loader
for (i = 0; i < PTES_PER_PAGE; i++) SET_PTE(PTOB(i), 0);
}
