void allocate_frame(int pid, int type, uint32 vpage)
{
int i;
for (i = 0; i < NFRAMES; i++)
{
if(invertpagetable[page_head].empty == TRUE)
{
invertpagetable[page_head].pid = pid;
invertpagetable[page_head].type = type;
invertpagetable[page_head].empty = FALSE;
invertpagetable[page_head].vpage = vpage;
return;
}
page_head = (++page_head) % NFRAMES;
}
kprintf ("Could not find any empty pages. Must evict\n");
if (policy == FIFO)
{
kprintf("Eviction Policy: FIFO\n");
uint32 evict_page = (page_head + 1) % NFRAMES;
while(invertpagetable[page_head].type != FRAME_REG)
{
evict_page = (page_head + 1) % NFRAMES;
if (evict_page == (page_head + 1) % NFRAMES)
{
kprintf ("All frames filled by directories or tables!\n");
}
}
page_head = evict_page;
int old_pid = invertpagetable[page_head].pid;
int old_type = invertpagetable[page_head].type;
int old_vpage = invertpagetable[page_head].vpage;
int old_bs = bs_page(old_vpage);
int old_pd = pd(old_vpage);
int old_pt = pt(old_vpage);
struct procent *old_prptr = &proctab[old_pid];
pd_t *old_pd_t = old_prptr->prpagedir;
pt_t *old_pt_t = (old_pd_t[old_pd].pd_base << 12);
old_pt_t[old_pt].pt_pres = 0;
char* addr = (char *)frame2addr(page_head);
if(open_bs(old_prptr->prbs) == (uint32)-1 ||
write_bs(addr, old_prptr->prbs, old_bs)||
close_bs(old_prptr->prbs) == (uint32)-1)
{
kprintf("Backing store error during eviction!");
return;
}
invertpagetable[page_head].pid = pid;
invertpagetable[page_head].type = type;
invertpagetable[page_head].empty = FALSE;
invertpagetable[page_head].vpage = vpage;
}
}
/*-------------------------------------------------------------------------
* free_frm - free a frame
*-------------------------------------------------------------------------
*/
SYSCALL free_frm(int i)
{
STATWORD ps;
disable(ps);
unsigned long v_addr;
unsigned int pt_offset;
unsigned int pd_offset;
unsigned long pdbr;
pd_t *pd_entry;
pt_t *pt_entry;
int bs_store;
int page_num;
if(frm_tab[i].fr_type == FR_PAGE)
{
// kprintf("Inside free frame starting \n");
v_addr = frm_tab[i].fr_vpno;
pdbr = proctab[frm_tab[i].fr_pid].pdbr;
pd_offset = v_addr>>10;
pt_offset = v_addr & 0x000003FF;
pd_entry = pdbr+(pd_offset*sizeof(pd_t));
pt_entry = (pd_entry->pd_base*NBPG)+(pt_offset*sizeof(pt_t));
bs_store = proctab[frm_tab[i].fr_pid].store;
page_num = frm_tab[i].fr_vpno-proctab[frm_tab[i].fr_pid].vhpno;
// kprintf("Before write bs bs_store %d and page_num %d\n", bs_store, page_num);
write_bs((i+FRAME0)*NBPG, bs_store, page_num);
// kprintf("After write bs\n");
pt_entry->pt_pres = 0;
pt_entry->pt_write = 0;
pt_entry->pt_base = 0;
frm_tab[i].cookie = 0;
frm_tab[i].fr_dirty = 0;
frm_tab[i].fr_loadtime = 0;
frm_tab[i].fr_pid = -1;
frm_tab[i].fr_refcnt = 0;
frm_tab[i].fr_status = FRM_UNMAPPED;
frm_tab[i].fr_type = FR_PAGE;
frm_tab[i].fr_vpno = BASE_VIRTUAL_PAGE;
frm_tab[i].next_frame = -1;
frm_tab[pd_entry->pd_base-FRAME0].fr_refcnt--;
if(frm_tab[pd_entry->pd_base-FRAME0].fr_refcnt == 0)
{
frm_tab[pd_entry->pd_base-FRAME0].cookie = 0;
frm_tab[pd_entry->pd_base-FRAME0].fr_dirty = 0;
frm_tab[pd_entry->pd_base-FRAME0].fr_loadtime = 0;
frm_tab[pd_entry->pd_base-FRAME0].fr_pid = -1;
frm_tab[pd_entry->pd_base-FRAME0].fr_refcnt = 0;
frm_tab[pd_entry->pd_base-FRAME0].fr_status = FRM_UNMAPPED;
frm_tab[pd_entry->pd_base-FRAME0].fr_type = FR_PAGE;
frm_tab[pd_entry->pd_base-FRAME0].fr_vpno = BASE_VIRTUAL_PAGE;
frm_tab[pd_entry->pd_base-FRAME0].next_frame = -1;
pd_entry->pd_pres = 0;
}
}
SYSCALL pfint()
{
unsigned long cr2,physical_addr;
virt_addr_t * vaddr;
int vp,s,o,avail,*store,*pageth;
unsigned int p,q,pt;
pd_t *pd;
pt_t *new_pt;
STATWORD ps;
// Disable interrupts
disable(ps);
if(GDB)
kprintf("\n*************pfint is running!************\n");
// Get the faulted address. The processor loads the CR2 register
// with the 32-bit address that generated the exception.
/* 1. Get the faulted address. */
cr2 = read_cr2();
vaddr = (virt_addr_t *)(&cr2);
if(GDB)
kprintf("&cr2=%x, cr2=%x, &vaddr=%x, vaddr=%x\n",&cr2,cr2,&vaddr,vaddr);
/* 2. Let 'vp' be the virtual page number of the page containing of the faulted address */
vp = a2pno(cr2);
if(GDB)
kprintf("vp=%d,\n",vp);
/* 3. Let pd point to the current page directory. */
pd = proctab[currpid].pdbr;
if(GDB)
kprintf("pd=%x,\n",pd);
/* 4. Check that a is a legal address (i.e., it has been mapped).
If it is not, print an error message and kill the process. */
pageth = getmem( sizeof(int *) );
store = getmem( sizeof(int *) );
if( SYSERR == bsm_lookup(currpid, vp, store, pageth)){
kprintf("ERROR: This virtual address hasn't been mapped!\n");
kill(currpid);
}
/* 5. Let p be the upper ten bits of a. [p represents page dirctory offset] */
/* 6. Let q be the bits [21:12] of a. [p represents page table offset.]
/* 7.1 Let pt point to the pth page table.*/
p = vaddr->pd_offset;
q = vaddr->pt_offset;
pt = vaddr->pg_offset;
if(GDB)
kprintf("p=%d,q=%d,pt=%d\n",p,q,pt);
/* 7.2 If the pth page table does not exist obtain a frame for it and initialize it. */
if(pd[p].pd_pres != 1){
if(GDB)
kprintf("**obtain a frame for the new page table. \n");
avail = get_frm(); //get the id of a new frame from frm_tab[];
if (avail == -1) {
if(GDB)
kprintf("Could not create page table!\n");
restore(ps);
return SYSERR;
}
//initialize frame[avail], update the process_id and frame_type of this frame.
init_frm(avail, currpid, FR_TBL);
frm_tab[avail].fr_upper_t = pa2frid((unsigned long) pd);
if(GDB)
kprintf("upper page table @frame[%d] pd=%x, a2pno(pd)=%d\n",frm_tab[avail].fr_upper_t, pd, a2pno((unsigned long) pd));
new_pt = frid2pa(avail);
init_pt(new_pt);
//update this page_table_entry in the page_directory.
pd[p].pd_pres = 1;
pd[p].pd_write = 1;
pd[p].pd_user = 0; // not sure about the usage;
pd[p].pd_pwt = 0;
pd[p].pd_pcd = 0;
pd[p].pd_acc = 0;
pd[p].pd_mbz = 0;
pd[p].pd_fmb = 0;
pd[p].pd_global = 0;
pd[p].pd_avail = 0; // not in use right now.
pd[p].pd_base = a2pno((unsigned long) new_pt); /* location of page table */
if(GDB)
kprintf("New page_table(%x)@frame[%d] updated in page_directory[%d]@(frame[%d])\n",
new_pt, avail, p, frm_tab[avail].fr_upper_t);
if(GDB)
kprintf("q=%d, new_pt[q]=%x, new_pt=%x, pd[p].pd_base=%d\n",
q, new_pt[q], new_pt, pd[p].pd_base);
}
//if the page table has already existed, just need to refcnt++;
else
{
int avail = pd[p].pd_base -1024;
frm_tab[avail].fr_refcnt++;
if(GDB)
kprintf("frm_tab[%d].fr_refcnt = %d, frame_type: %d\n",avail, frm_tab[avail].fr_refcnt, frm_tab[avail].fr_type);
}
/* 8.1 Using the backing store map, find the store s and page offset o which correspond to vp. */
//already saved in 'store' and 'pageth'
s = *store;
o = *pageth;
/* 8.2 In the inverted page table increment the reference count of the frame which holds pt.
This indicates that one more of pt's entries is marked "present." */
avail = find_frm(currpid,vp);
if (avail == -1)
{
if(GDB)
kprintf("allocating a page for the page fault\n");
avail = get_frm();
if(avail == -1)
{
if(GDB)
kprintf("ATTENTION! Frames full. ###Replacement NEEDED!###\n");
int frame_number = proctab[currpid].nframes-1;
int frame_id = proc_frames[currpid][0];
//update_proc_frames(pid,frame_number);
int i;
for (i = 0; i+1 < frame_number; ++i)
{
proc_frames[currpid][i] = proc_frames[currpid][i+1];
}
proctab[currpid].nframes = frame_number;
int pid = frm_tab[frame_id].fr_pid;
int upper_id = frm_tab[frame_id].fr_upper_t;
vp = frm_tab[frame_id].fr_vpno;
if(GDB)
kprintf("currpid=%d, frame[%d].pid=%d .vpno=%d, upper_frame[%d].ref=%d\n",currpid,frame_id,pid,vp,upper_id,frm_tab[upper_id].fr_refcnt);
p = vp>>10;
q = vp &0x003ff;
new_pt = vp2pa(pd[p].pd_base);
new_pt[q].pt_pres = 0;
new_pt[q].pt_write = 1;
new_pt[q].pt_base = 0;
if(GDB)
kprintf("pd_offset=%d, pt_offset=%d, pt_dirty=%d\n",p,q,new_pt[q].pt_dirty);
if(new_pt[q].pt_dirty == 1)
{
//write back and
pageth = getmem( sizeof(int *) );
store = getmem( sizeof(int *) );
if( SYSERR == bsm_lookup(currpid, vp, store, pageth)){
kprintf("ERROR: This virtual address hasn't been mapped!\n");
kill(currpid);
}
if(GDB)
kprintf("maping found: {pid: %d, vpno: %d, store: %d, pageth: %d}\n",currpid,vp,*store,*pageth);
write_bs((char *)new_pt, *store, *pageth);
}
init_pt(new_pt);
reset_frm(frame_id);
frm_tab[upper_id].fr_refcnt -= 2; //it is 2, not 1.
if(frm_tab[upper_id].fr_refcnt <= 0){
//mark the appropriate entry in pd as being not present, and free pt.
}
//invalidate the TLB entry for the page vp using the invlpg instruction
if(pid == currpid) {
set_PDBR(currpid);
}
}
else
{
init_frm(avail, currpid, FR_PAGE);
frm_tab[avail].fr_upper_t = pd[p].pd_base-FRAME0;
if(GDB)
kprintf("upper page table @frame[%d]\n",frm_tab[avail].fr_upper_t);
frm_tab[avail].fr_vpno = vp;
int counter = proctab[currpid].nframes;
proc_frames[currpid][counter] = frm_tab[avail].fr_id;
proctab[currpid].nframes++;
if(GDB)
kprintf("proc_frames[%d][%d] = frame[%d]\n",currpid,counter,avail);
// Add this frame to head of the frame list within the bs of this process
//(frm_tab[avail].bs_next)->fr_vpno
//, proctab[currpid].bsmap[s].frames->bs_next
if(GDB)
kprintf("&frm_tab[avail].bs_next = %x\n",frm_tab[avail].bs_next, &frm_tab[avail].bs_next);
if(GDB)
kprintf("proctab[%d].bsmap[%d].frames = %x, ->vpno=%d, ->bs_next=%x\n",currpid, s, proctab[currpid].bsmap[s].frames, proctab[currpid].bsmap[s].frames->fr_vpno, proctab[currpid].bsmap[s].frames->bs_next);
frm_tab[avail].bs_next = getmem(sizeof(fr_map_t *));
frm_tab[avail].bs_next = proctab[currpid].bsmap[s].frames;
proctab[currpid].bsmap[s].frames = &frm_tab[avail];
fr_map_t *frame = proctab[currpid].bsmap[s].frames;
int i = frame->fr_vpno;
if(GDB)
kprintf("i = %d\n",i);
if(GDB)
kprintf("~~~frame[%d] linked to frame[%d]\n", avail, frame->bs_next==NULL?-1:frame->bs_next->fr_id);
if(GDB)
kprintf("frame[%d].bs_next = %x, &**=%x\n",avail,frm_tab[avail].bs_next, &frm_tab[avail].bs_next);
if(GDB)
kprintf("proctab[%d].bsmap[%d].frames = %x, ->vpno=%d, ->bs_next=%x\n",currpid, s, proctab[currpid].bsmap[s].frames, proctab[currpid].bsmap[s].frames->fr_vpno, proctab[currpid].bsmap[s].frames->bs_next);
if(GDB)
kprintf("Mapping frame[%d](ppno[%d]) to {pid[%d], vpno[%d]} -> {bs[%d],offset:%d}\n",
avail,frid2vpno(avail),currpid,vp,s,o);
physical_addr = frid2pa(avail);
read_bs(physical_addr,s,o);
if(GDB)
kprintf("copied from bs[%d]:offset[%d] to vp[%d]@(%x)\n",s,o,vp,vp2pa(vp));
}
}
int free_frame(frame_t * frame)
{
intmask mask;
mask = disable();
//LOG("Freeing");
//print_frame(frame);
if(frame->id <5)
{
LOG(" WHAT THE F**K %d %d", frame->id, frame->type);
restore(mask);
return OK;
}
//kprintf("id %d type %d ", frame->id, frame->type);
//print_fifo_list();
//kprintf("\n");
if(frame == NULL)
{
restore(mask);
return SYSERR;
}
else if(!FRAMEID_IS_VALID(frame->id))
{
restore(mask);
return SYSERR;
}
else if(frame->type == FREE)
{
restore(mask);
return OK;
}
else if(frame->type == PAGE){
//print_fifo_list();
//LOG("Got here 0.5");
//3. Using the inverted page table, get vp, the virtual page number of the page to be replaced.
uint32 vp = frame->vp_no;
//4. Let a be vp*4096 (the first virtual address on page vp).
hook_pswap_out(vp, frame->id + FRAME0);
uint32 a = vp*PAGE_SIZE;
virtual_addr * virt = (virtual_addr *) &a;
//5. Let p be the high 10 bits of a. Let q be bits [21:12] of a.
uint32 p = virt->page_directory_offset;
uint32 q = virt->page_table_offset;
//6. Let pid be the process id of the process owning vp.
pid32 pid = frame->pid;
//7. Let pd point to the page directory of process pid.
struct procent *prptr; /* Ptr to process table entry */
prptr = &proctab[pid];
pd_t * pd = prptr->pagedir;
if( pd == NULL)
{
LOG(" pd doesn't exist ");
restore(mask);
return SYSERR;
}
bool8 pt_pres = FALSE;
pt_pres = (bool8) pd[p].pd_pres;
bool8 pg_pres = FALSE;
bool8 dirty = FALSE;
if(pt_pres)
{ //8. Let pt point to the pid's p_th page table.
pt_t * pt = (pt_t *) ((pd[p].pd_base) * PAGE_SIZE);
pg_pres = (bool8) pt[q].pt_pres;
uint32 pg_base = (uint32) pt[q].pt_base;
if(pg_pres){
if((uint32)FRAMEID_TO_VPAGE(frame->id) == pg_base)
{
pg_pres = TRUE;
dirty = pt[q].pt_dirty;
}
else
{
pg_pres = FALSE;
}
}
}
if(pg_pres)
{
frame_t * pt_frame = &frames[(pd[p].pd_base) - FRAME0];
pt_t * pt = (pt_t *) ((pd[p].pd_base) * PAGE_SIZE);
//9. Mark the appropriate entry of pt as not present.
pt[q].pt_pres = 0;
if(pt_frame->type == VPTBL){
decr_frame_refcount(pt_frame);
if(pt_frame->refcount == 0){
pd[p].pd_pres = 0;
free_frame(pt_frame);
}
bzero((char *)&pt[q], sizeof(pt_t));
}
else if(pt_frame->type == GPTBL)
{
// kprintf(" Uh OH");
}
// If the reference count has reached zero, you should mark the appropriate entry in pd as "not present."
// This conserves frames by keeping only page tables which are necessary.
//LOG("Got here 1.5");
//If the dirty bit for page vp was set in its page table, you must do the following:
//a) Using the backing store map, find the store and page offset within the store, given pid and a.
// If the lookup fails, something is wrong. Print an error message and kill the process with id pid.
//b) Write the page back to the backing store.
//LOG("Got here 2");
if(dirty){
bsd_t bs_store_id;
int bs_store_page_offset;
if(SYSERR == bs_map_check(pid, vp, &bs_store_id, &bs_store_page_offset))
{
kprintf("FATAL :Can't find the bs_map");
restore(mask);
kill(currpid);
return SYSERR;
}
//print_frame(frame);
if(BACKSTORE_ID_IS_VALID(frame->backstore) && BACKSTORE_OFFSET_IS_VALID(frame->backstore_offset) && frame->backstore == bs_store_id && frame->backstore_offset == bs_store_page_offset)
{
//LOG("Frame %d was dirty", frame->id);
open_bs(frame->backstore);
write_bs(FRAMEID_TO_PHYSICALADDR(frame->id), frame->backstore, frame->backstore_offset);
close_bs(frame->backstore);
}
//else
//{
// print_frame(frame);
// kprintf("Fatal error: Cannot locate backstore for vpage %d to swap out page for pid %d ", vp, pid);
// kill(pid);
// initialize_frame(frame);
// restore(mask);
// return SYSERR;
//}
}
else{
//print_frame(frame);
}
}
//LOG("Got here 1");
//10. If the page being removed belongs to the current process,
// invalidate the TLB entry for the page vp, using the invlpg instruction (see Intel Manual, volumes II and III for more details on this instruction).
// 11. In the inverted page table, decrement the reference count of the frame occupied by pt.
//LOG(" Free frame");
//print_frame(frame);
enable_paging();
initialize_frame(frame);
// Update page table entries associated with this frame
// set the frame to be free
}
else if(frame->type == VPTBL)
{
evict_from_fifo_list(frame);
hook_ptable_delete(frame->id + FRAME0);
enable_paging();
initialize_frame(frame);
}
else if(frame->type == DIR)
{
struct procent * prptrNULL = &proctab[NULLPROC];
pd_t * null_pg_dir = prptrNULL->pagedir;
struct procent *prptr; /* Ptr to process table entry */
prptr = &proctab[currpid];
if(prptr->pagedir!= null_pg_dir)
{
evict_from_fifo_list(frame);
prptr->pagedir = prptrNULL->pagedir;
switch_page_directory(prptr->pagedir);
enable_paging();
initialize_frame(frame);
}
}
restore(mask);
return OK;
}