inline static void *malloc_pages(size_t len, size_t alignment)
{
void *p;
CHECK_USED_AGAINST_MAX(len);
p = smemalign(alignment, len);
memset(p, 0, len);
ACTUALLY_ALLOCATING_PAGES(len);
LOGICALLY_ALLOCATING_PAGES(len);
return p;
}
/** @brief Function deals with the page fault
*
* This is an amazing function.
*
* @param void
* @return void
*/
void page_fault_handler(void){
int fault_addr = get_cr2();
mutex_lock(&cur_task->pcb_mutex);
uint32_t align_addr = fault_addr & PGALIGN_MASK;
uint32_t *ptep = NULL;
Page *phy_page = NULL;
phy_page = page_lookup(cur_task->task_pgdir, align_addr, &ptep);
uint32_t pte = *ptep;
/** Catch COW page fualt */
if((ptep != NULL) &&(pte & PTE_P) && (pte & PTE_COW))
{
mutex_lock(&mtx_m.frame_mutex);
if(phy_page->pp_ref == 1)
{
*ptep = (pte | PTE_W) &(~PTE_COW);
mutex_unlock(&mtx_m.frame_mutex);
}
else{
mutex_unlock(&mtx_m.frame_mutex);
if(pte & PTE_RWMARK){
lprintf("ERROR: Cannot access TXT or ro_data area!");
mutex_unlock(&cur_task->pcb_mutex);
sys_vanish();
return;
}
Page *new_page = page_alloc();
if(new_page == NULL){
lprintf("ERROR: No pages for COW in page_fault_handler");
mutex_unlock(&cur_task->pcb_mutex);
sys_vanish();
return;
}
uint32_t *temp_page = smemalign(PAGE_SIZE, PAGE_SIZE);
if (temp_page == NULL){
lprintf("ERROR: No memory for temp_page in page_fault_handler!");
mutex_unlock(&cur_task->pcb_mutex);
sys_vanish();
return;
}
/* Copy the physical page to a temporary page in kernel space */
memcpy((void*)temp_page, (void*)align_addr, PAGE_SIZE);
if(page_insert(cur_task->task_pgdir, new_page, align_addr,
PTE_P | PTE_U | PTE_W) < 0)
{
lprintf("ERROR: No memory for COW in page_fault_handler");
mutex_unlock(&cur_task->pcb_mutex);
sys_vanish();
return;
}
/* Copy the content to the new mapped physical page */
memcpy((void*)align_addr, (void*)temp_page, PAGE_SIZE);
/* Free the temp physical page */
sfree(temp_page, PAGE_SIZE);
mutex_lock(&mtx_m.frame_mutex);
phy_page->pp_ref--;
mutex_unlock(&mtx_m.frame_mutex);
}
}
/** Catch the ZFOD */
else if ((ptep != NULL) &&(pte & PTE_P) && (pte & PTE_ZFOD))
{
Page *pg = page_alloc();
if(pg == NULL){
lprintf("ERROR: No pages for ZFOD in page_fault_handler");
mutex_unlock(&cur_task->pcb_mutex);
sys_vanish();
return;
}
uint32_t perm = PTE_P | PTE_U | PTE_W;
if(page_insert(cur_task->task_pgdir, pg, align_addr, perm) < 0)
{
lprintf("ERROR: No memory for ZFOD in page_fault_handler");
mutex_unlock(&cur_task->pcb_mutex);
sys_vanish();
return;
}
bzero((void*)align_addr, PAGE_SIZE);
}
/* Check if installed swexn handler can fix this up */
else if(cur_thread->swexn_eip != NULL)
{
mutex_unlock(&cur_task->pcb_mutex);
swexn_handler(HAS_ERROR_CODE, SWEXN_CAUSE_PAGEFAULT);
return;
}
else{
mutex_unlock(&cur_task->pcb_mutex);
sys_vanish();
return;
}
mutex_unlock(&cur_task->pcb_mutex);
return;
}
