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#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
int
fault(ulong addr, int read)
{
Segment *s;
char *sps;
if(up == nil)
panic("fault: nil up");
if(up->nlocks.ref)
print("fault: addr %#p: nlocks %ld\n", addr, up->nlocks.ref);
sps = up->psstate;
up->psstate = "Fault";
spllo();
m->pfault++;
for(;;) {
s = seg(up, addr, 1); /* leaves s->lk qlocked if seg != nil */
if(s == 0) {
up->psstate = sps;
return -1;
}
if(!read && (s->type&SG_RONLY)) {
qunlock(&s->lk);
up->psstate = sps;
return -1;
}
if(fixfault(s, addr, read, 1) == 0) /* qunlocks s->lk */
break;
}
up->psstate = sps;
return 0;
}
static void
faulterror(char *s, Chan *c, int freemem)
{
char buf[ERRMAX];
if(c && c->path){
snprint(buf, sizeof buf, "%s accessing %s: %s", s, c->path->s, up->errstr);
s = buf;
}
if(up->nerrlab) {
postnote(up, 1, s, NDebug);
error(s);
}
pexit(s, freemem);
}
void (*checkaddr)(ulong, Segment *, Page *);
ulong addr2check;
int
fixfault(Segment *s, ulong addr, int read, int doputmmu)
{
int type;
int ref;
Pte **p, *etp;
ulong mmuphys=0, soff;
Page **pg, *lkp, *new;
Page *(*fn)(Segment*, ulong);
addr &= ~(BY2PG-1);
soff = addr-s->base;
p = &s->map[soff/PTEMAPMEM];
if(*p == 0)
*p = ptealloc();
etp = *p;
pg = &etp->pages[(soff&(PTEMAPMEM-1))/BY2PG];
type = s->type&SG_TYPE;
if(pg < etp->first)
etp->first = pg;
if(pg > etp->last)
etp->last = pg;
switch(type) {
default:
panic("fault");
break;
case SG_TEXT: /* Demand load */
if(pagedout(*pg))
pio(s, addr, soff, pg);
mmuphys = PPN((*pg)->pa) | PTERONLY|PTEVALID;
(*pg)->modref = PG_REF;
break;
case SG_BSS:
case SG_SHARED: /* Zero fill on demand */
case SG_STACK:
if(*pg == 0) {
new = newpage(1, &s, addr);
if(s == 0)
return -1;
*pg = new;
}
goto common;
case SG_DATA:
common: /* Demand load/pagein/copy on write */
if(pagedout(*pg))
pio(s, addr, soff, pg);
/*
* It's only possible to copy on write if
* we're the only user of the segment.
*/
if(read && conf.copymode == 0 && s->ref == 1) {
mmuphys = PPN((*pg)->pa)|PTERONLY|PTEVALID;
(*pg)->modref |= PG_REF;
break;
}
lkp = *pg;
lock(lkp);
if(lkp->image == &swapimage)
ref = lkp->ref + swapcount(lkp->daddr);
else
ref = lkp->ref;
if(ref == 1 && lkp->image){
/* save a copy of the original for the image cache */
duppage(lkp);
ref = lkp->ref;
}
unlock(lkp);
if(ref > 1){
new = newpage(0, &s, addr);
if(s == 0)
return -1;
*pg = new;
copypage(lkp, *pg);
putpage(lkp);
}
mmuphys = PPN((*pg)->pa) | PTEWRITE | PTEVALID;
(*pg)->modref = PG_MOD|PG_REF;
break;
case SG_PHYSICAL:
if(*pg == 0) {
fn = s->pseg->pgalloc;
if(fn)
*pg = (*fn)(s, addr);
else {
new = smalloc(sizeof(Page));
new->va = addr;
new->pa = s->pseg->pa+(addr-s->base);
new->ref = 1;
*pg = new;
}
}
if (checkaddr && addr == addr2check)
(*checkaddr)(addr, s, *pg);
mmuphys = PPN((*pg)->pa) |PTEWRITE|PTEUNCACHED|PTEVALID;
(*pg)->modref = PG_MOD|PG_REF;
break;
}
qunlock(&s->lk);
if(doputmmu)
putmmu(addr, mmuphys, *pg);
return 0;
}
void
pio(Segment *s, ulong addr, ulong soff, Page **p)
{
Page *new;
KMap *k;
Chan *c;
int n, ask;
char *kaddr;
ulong daddr;
Page *loadrec;
retry:
loadrec = *p;
if(loadrec == 0) { /* from a text/data image */
daddr = s->fstart+soff;
new = lookpage(s->image, daddr);
if(new != nil) {
*p = new;
return;
}
c = s->image->c;
ask = s->flen-soff;
if(ask > BY2PG)
ask = BY2PG;
}
else { /* from a swap image */
daddr = swapaddr(loadrec);
new = lookpage(&swapimage, daddr);
if(new != nil) {
putswap(loadrec);
*p = new;
return;
}
c = swapimage.c;
ask = BY2PG;
}
qunlock(&s->lk);
new = newpage(0, 0, addr);
k = kmap(new);
kaddr = (char*)VA(k);
while(waserror()) {
if(strcmp(up->errstr, Eintr) == 0)
continue;
kunmap(k);
putpage(new);
faulterror(Eioload, c, 0);
}
n = devtab[c->type]->read(c, kaddr, ask, daddr);
if(n != ask)
faulterror(Eioload, c, 0);
if(ask < BY2PG)
memset(kaddr+ask, 0, BY2PG-ask);
poperror();
kunmap(k);
qlock(&s->lk);
if(loadrec == 0) { /* This is demand load */
/*
* race, another proc may have gotten here first while
* s->lk was unlocked
*/
if(*p == 0) {
new->daddr = daddr;
cachepage(new, s->image);
*p = new;
}
else
putpage(new);
}
else { /* This is paged out */
/*
* race, another proc may have gotten here first
* (and the pager may have run on that page) while
* s->lk was unlocked
*/
if(*p != loadrec){
if(!pagedout(*p)){
/* another process did it for me */
putpage(new);
goto done;
} else {
/* another process and the pager got in */
putpage(new);
goto retry;
}
}
new->daddr = daddr;
cachepage(new, &swapimage);
*p = new;
putswap(loadrec);
}
done:
if(s->flushme)
memset((*p)->cachectl, PG_TXTFLUSH, sizeof((*p)->cachectl));
}
/*
* Called only in a system call
*/
int
okaddr(ulong addr, ulong len, int write)
{
Segment *s;
if((long)len >= 0) {
for(;;) {
s = seg(up, addr, 0);
if(s == 0 || (write && (s->type&SG_RONLY)))
break;
if(addr+len > s->top) {
len -= s->top - addr;
addr = s->top;
continue;
}
return 1;
}
}
pprint("suicide: invalid address %#lux/%lud in sys call pc=%#lux\n", addr, len, userpc());
return 0;
}
void
validaddr(ulong addr, ulong len, int write)
{
if(!okaddr(addr, len, write)){
postnote(up, 1, "sys: bad address in syscall", NDebug);
error(Ebadarg);
}
}
/*
* &s[0] is known to be a valid address.
*/
void*
vmemchr(void *s, int c, int n)
{
int m;
ulong a;
void *t;
a = (ulong)s;
while(PGROUND(a) != PGROUND(a+n-1)){
/* spans pages; handle this page */
m = BY2PG - (a & (BY2PG-1));
t = memchr((void*)a, c, m);
if(t)
return t;
a += m;
n -= m;
if(a < KZERO)
validaddr(a, 1, 0);
}
/* fits in one page */
return memchr((void*)a, c, n);
}
Segment*
seg(Proc *p, ulong addr, int dolock)
{
Segment **s, **et, *n;
et = &p->seg[NSEG];
for(s = p->seg; s < et; s++) {
n = *s;
if(n == 0)
continue;
if(addr >= n->base && addr < n->top) {
if(dolock == 0)
return n;
qlock(&n->lk);
if(addr >= n->base && addr < n->top)
return n;
qunlock(&n->lk);
}
}
return 0;
}
extern void checkmmu(ulong, ulong);
void
checkpages(void)
{
int checked;
ulong addr, off;
Pte *p;
Page *pg;
Segment **sp, **ep, *s;
if(up == nil)
return;
checked = 0;
for(sp=up->seg, ep=&up->seg[NSEG]; sp<ep; sp++){
s = *sp;
if(s == nil)
continue;
qlock(&s->lk);
for(addr=s->base; addr<s->top; addr+=BY2PG){
off = addr - s->base;
p = s->map[off/PTEMAPMEM];
if(p == 0)
continue;
pg = p->pages[(off&(PTEMAPMEM-1))/BY2PG];
if(pg == 0 || pagedout(pg))
continue;
checkmmu(addr, pg->pa);
checked++;
}
qunlock(&s->lk);
}
print("%ld %s: checked %d page table entries\n", up->pid, up->text, checked);
}