pd_entry* vmmngr_pdirectory_lookup_entry(pdirectory* p, virtual_addr addr)
{
if (p)
return &p->entries[PAGE_DIR_INDEX(addr)];
set_last_error(EINVAL, VMEM_BAD_ARGUMENT, EO_VMMNGR);
return 0;
}
void do_page_fault (process_t *proc,
unsigned int linear_addr,
long error_code)
{
page_frame_t *new_page, *page_frame;
unsigned int phys_frame_addr;
pagetable_entry_t *pte;
int pf_ok;
//Only handle usermode writes to present pages (not present ones later (pagein))
//if ((error_code & PAGE_FAULT_P) &&
// (error_code & PAGE_FAULT_RW) &&
// (error_code & PAGE_FAULT_US))
if (error_code & PAGE_FAULT_P) {
//
// CHECK IF WE REALLY SHOULD COPY THIS
// (with vm_blocks)
//
pf_ok = 0;
//Only write pagefaults handled
if (error_code & PAGE_FAULT_RW) {
if ((linear_addr >= proc->vm_data.vm_start) &&
(linear_addr < proc->vm_data.vm_end) &&
(proc->vm_data.vm_flags & VM_READWRITE))
pf_ok = 1;
if ((linear_addr >= proc->vm_stack.vm_start) &&
(linear_addr < proc->vm_stack.vm_end) &&
(proc->vm_stack.vm_flags & VM_READWRITE))
pf_ok = 1;
if ((linear_addr >= proc->vm_kernel_stack.vm_start) &&
(linear_addr < proc->vm_kernel_stack.vm_end) &&
(proc->vm_kernel_stack.vm_flags & VM_READWRITE))
pf_ok = 1;
}
if (!pf_ok)
{
printf ("*real* page fault (out of bounds), should terminate task!\n");
printf ("present=%s, write=%s, usermode=%s, address=0x%x, dir=0x%x\n",
((int) error_code & PAGE_FAULT_P) ? "true" : "false",
((int) error_code & PAGE_FAULT_RW) ? "true" : "false",
((int) error_code & PAGE_FAULT_US) ? "true" : "false",
linear_addr,
(int) (proc->tss.cr3));
printf ("data start 0x%x, data end 0x%x, flags 0x%x\n",
(int) proc->vm_data.vm_start,
(int) proc->vm_data.vm_end,
(int) proc->vm_data.vm_flags);
printf ("stack start 0x%x, stack end 0x%x, flags 0x%x\n",
(int) proc->vm_stack.vm_start,
(int) proc->vm_stack.vm_end,
(int) proc->vm_stack.vm_flags);
while(1);
}
//Get dir
pte = (pagetable_entry_t *) proc->tss.cr3;
//Get table from dir
pte = (pagetable_entry_t *) PTE_TO_PHYSICAL(pte[PAGE_DIR_INDEX(linear_addr)]);
//Get page from table
phys_frame_addr = PTE_TO_PHYSICAL(pte[PAGE_TABLE_INDEX(linear_addr)]);
//Check use count of this page frame
page_frame = &page_frames[PHYS_TO_FRAME_NR (phys_frame_addr)];
if (page_frame->count > 1)
{
//Page in use by others, we need to copy
new_page = get_free_page();
if (new_page == NULL)
panic ("Can't COW, no free pages!");
//Copy page
//printf ("COW(copy, 0x%x->0x%x)\n", phys_frame_addr, new_page->page_frame_nr * PAGE_SIZE);
copy_page (phys_frame_addr, new_page->page_frame_nr * PAGE_SIZE);
//Remap pagetable
map_page (proc, new_page->page_frame_nr * PAGE_SIZE,
linear_addr & PHYS_PAGE_MASK, PAGE_PRESENT | PAGE_USER | PAGE_WRITEABLE);
//Decrease use count
page_frame->count--;
} else if (page_frame->count == 1)
{
//The page is not in use by others, just remap
//printf ("COW(remap, 0x%x)\n", linear_addr);
//Remap pagetable
map_page (proc, phys_frame_addr,
linear_addr & PHYS_PAGE_MASK, PAGE_PRESENT | PAGE_USER | PAGE_WRITEABLE);
} else
{
printf ("Page frame has invalid use count!\n");
while (1);
}
//Schedule next process
schedule();
} else {
printf ("*real* page fault (page not present), should terminate task!\n");
printf ("present=%s, write=%s, usermode=%s, address=0x%x, dir=0x%x\n",
((int) error_code & PAGE_FAULT_P) ? "true" : "false",
((int) error_code & PAGE_FAULT_RW) ? "true" : "false",
((int) error_code & PAGE_FAULT_US) ? "true" : "false",
linear_addr,
(int) (proc->tss.cr3));
printf ("data start 0x%x, data end 0x%x, flags 0x%x\n",
(int) proc->vm_data.vm_start,
(int) proc->vm_data.vm_end,
(int) proc->vm_data.vm_flags);
printf ("stack start 0x%x, stack end 0x%x, flags 0x%x\n",
(int) proc->vm_stack.vm_start,
(int) proc->vm_stack.vm_end,
(int) proc->vm_stack.vm_flags);
while(1);
}
}
