ref: a44a1dbd19c2a9b05b497e32853e57ca88495397
dir: /sys/src/9/port/segment.c/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
int imagereclaim(int);
/*
* Attachable segment types
*/
static Physseg physseg[10] = {
{ SG_SHARED, "shared", 0, SEGMAXSIZE },
{ SG_BSS, "memory", 0, SEGMAXSIZE },
{ 0, 0, 0, 0 },
};
static Lock physseglock;
#define IHASHSIZE 64
#define ihash(s) imagealloc.hash[s%IHASHSIZE]
static struct Imagealloc
{
Lock;
Image *list;
Image *free;
Image *hash[IHASHSIZE];
QLock ireclaim; /* mutex on reclaiming free images */
}imagealloc;
Segment* (*_globalsegattach)(Proc*, char*);
void
initseg(void)
{
Image *i, *ie;
imagealloc.list = xalloc(conf.nimage*sizeof(Image));
if(imagealloc.list == nil)
panic("initseg: no memory for Image");
ie = &imagealloc.list[conf.nimage-1];
for(i = imagealloc.list; i < ie; i++)
i->next = i+1;
i->next = nil;
imagealloc.free = imagealloc.list;
}
Segment *
newseg(int type, uintptr base, ulong size)
{
Segment *s;
int mapsize;
if(size > (SEGMAPSIZE*PTEPERTAB))
error(Enovmem);
s = malloc(sizeof(Segment));
if(s == nil)
error(Enomem);
s->ref = 1;
s->type = type;
s->base = base;
s->top = base+(size*BY2PG);
s->size = size;
s->sema.prev = &s->sema;
s->sema.next = &s->sema;
mapsize = ROUND(size, PTEPERTAB)/PTEPERTAB;
if(mapsize > nelem(s->ssegmap)){
s->map = malloc(mapsize*sizeof(Pte*));
if(s->map == nil){
free(s);
error(Enomem);
}
s->mapsize = mapsize;
}
else{
s->map = s->ssegmap;
s->mapsize = nelem(s->ssegmap);
}
return s;
}
void
putseg(Segment *s)
{
Pte **pte, **emap;
Image *i;
if(s == nil)
return;
i = s->image;
if(i != nil) {
lock(i);
if(decref(s) != 0){
unlock(i);
return;
}
if(i->s == s)
i->s = nil;
unlock(i);
putimage(i);
} else if(decref(s) != 0)
return;
emap = &s->map[s->mapsize];
for(pte = s->map; pte < emap; pte++)
if(*pte != nil)
freepte(s, *pte);
if(s->map != s->ssegmap)
free(s->map);
if(s->profile != nil)
free(s->profile);
free(s);
}
void
relocateseg(Segment *s, uintptr offset)
{
Pte **pte, **emap;
Page **pg, **pe;
emap = &s->map[s->mapsize];
for(pte = s->map; pte < emap; pte++) {
if(*pte == nil)
continue;
pe = (*pte)->last;
for(pg = (*pte)->first; pg <= pe; pg++) {
if(!pagedout(*pg))
(*pg)->va += offset;
}
}
}
Segment*
dupseg(Segment **seg, int segno, int share)
{
int i, size;
Pte *pte;
Segment *n, *s;
SET(n);
s = seg[segno];
qlock(s);
if(waserror()){
qunlock(s);
nexterror();
}
switch(s->type&SG_TYPE) {
case SG_TEXT: /* New segment shares pte set */
case SG_SHARED:
case SG_PHYSICAL:
goto sameseg;
case SG_STACK:
n = newseg(s->type, s->base, s->size);
break;
case SG_BSS: /* Just copy on write */
if(share)
goto sameseg;
n = newseg(s->type, s->base, s->size);
break;
case SG_DATA: /* Copy on write plus demand load info */
if(segno == TSEG){
n = data2txt(s);
poperror();
qunlock(s);
return n;
}
if(share)
goto sameseg;
n = newseg(s->type, s->base, s->size);
incref(s->image);
n->image = s->image;
n->fstart = s->fstart;
n->flen = s->flen;
break;
}
size = s->mapsize;
for(i = 0; i < size; i++)
if((pte = s->map[i]) != nil)
n->map[i] = ptecpy(pte);
n->flushme = s->flushme;
if(s->ref > 1)
procflushseg(s);
poperror();
qunlock(s);
return n;
sameseg:
incref(s);
poperror();
qunlock(s);
return s;
}
void
segpage(Segment *s, Page *p)
{
Pte **pte, *etp;
uintptr soff;
Page **pg;
if(p->va < s->base || p->va >= s->top)
panic("segpage");
soff = p->va - s->base;
pte = &s->map[soff/PTEMAPMEM];
if((etp = *pte) == nil)
*pte = etp = ptealloc();
pg = &etp->pages[(soff&(PTEMAPMEM-1))/BY2PG];
*pg = p;
if(pg < etp->first)
etp->first = pg;
if(pg > etp->last)
etp->last = pg;
}
Image*
attachimage(int type, Chan *c, uintptr base, ulong len)
{
Image *i, **l;
lock(&imagealloc);
/*
* Search the image cache for remains of the text from a previous
* or currently running incarnation
*/
for(i = ihash(c->qid.path); i; i = i->hash) {
if(c->qid.path == i->qid.path) {
lock(i);
if(eqchantdqid(c, i->type, i->dev, i->qid, 0) && c->qid.type == i->qid.type)
goto found;
unlock(i);
}
}
/* dump pages of inactive images to free image structures */
while((i = imagealloc.free) == nil) {
unlock(&imagealloc);
if(imagereclaim(1000) == 0 && imagealloc.free == nil){
freebroken(); /* can use the memory */
resrcwait("no image after reclaim");
}
lock(&imagealloc);
}
imagealloc.free = i->next;
lock(i);
i->type = c->type;
i->dev = c->dev;
i->qid = c->qid;
l = &ihash(c->qid.path);
i->hash = *l;
*l = i;
found:
unlock(&imagealloc);
if(i->c == nil){
i->c = c;
c->flag &= ~CCACHE;
incref(c);
}
if(i->s == nil) {
incref(i);
if(waserror()) {
unlock(i);
putimage(i);
nexterror();
}
i->s = newseg(type, base, len);
i->s->image = i;
poperror();
}
else
incref(i->s);
return i;
}
extern int pagereclaim(Image*, int); /* page.c */
int
imagereclaim(int min)
{
static Image *i, *ie;
int j, n;
eqlock(&imagealloc.ireclaim);
if(i == nil){
i = imagealloc.list;
ie = &imagealloc.list[conf.nimage];
}
n = 0;
for(j = 0; j < conf.nimage; j++, i++){
if(i >= ie)
i = imagealloc.list;
if(i->ref == 0)
continue;
/*
* if there are no free image structures, only
* reclaim pages from inactive images.
*/
if(imagealloc.free != nil || i->ref == i->pgref){
n += pagereclaim(i, min - n);
if(n >= min)
break;
}
}
qunlock(&imagealloc.ireclaim);
return n;
}
void
putimage(Image *i)
{
Image *f, **l;
Chan *c;
int r;
if(i->notext){
decref(i);
return;
}
c = nil;
lock(i);
r = decref(i);
if(r == i->pgref){
/*
* all remaining references to this image are from the
* page cache, so close the chan.
*/
c = i->c;
i->c = nil;
}
if(r == 0){
l = &ihash(i->qid.path);
mkqid(&i->qid, ~0, ~0, QTFILE);
unlock(i);
lock(&imagealloc);
for(f = *l; f != nil; f = f->hash) {
if(f == i) {
*l = i->hash;
break;
}
l = &f->hash;
}
i->next = imagealloc.free;
imagealloc.free = i;
unlock(&imagealloc);
} else
unlock(i);
if(c != nil)
ccloseq(c); /* does not block */
}
long
ibrk(uintptr addr, int seg)
{
Segment *s, *ns;
uintptr newtop;
ulong newsize;
int i, mapsize;
Pte **map;
s = up->seg[seg];
if(s == nil)
error(Ebadarg);
if(addr == 0)
return s->base;
qlock(s);
/* We may start with the bss overlapping the data */
if(addr < s->base) {
if(seg != BSEG || up->seg[DSEG] == nil || addr < up->seg[DSEG]->base) {
qunlock(s);
error(Enovmem);
}
addr = s->base;
}
newtop = PGROUND(addr);
newsize = (newtop-s->base)/BY2PG;
if(newtop < s->top) {
/*
* do not shrink a segment shared with other procs, as the
* to-be-freed address space may have been passed to the kernel
* already by another proc and is past the validaddr stage.
*/
if(s->ref > 1){
qunlock(s);
error(Einuse);
}
mfreeseg(s, newtop, (s->top-newtop)/BY2PG);
s->top = newtop;
s->size = newsize;
qunlock(s);
flushmmu();
return 0;
}
for(i = 0; i < NSEG; i++) {
ns = up->seg[i];
if(ns == nil || ns == s)
continue;
if(newtop >= ns->base && newtop < ns->top) {
qunlock(s);
error(Esoverlap);
}
}
if(newsize > (SEGMAPSIZE*PTEPERTAB)) {
qunlock(s);
error(Enovmem);
}
mapsize = ROUND(newsize, PTEPERTAB)/PTEPERTAB;
if(mapsize > s->mapsize){
map = smalloc(mapsize*sizeof(Pte*));
memmove(map, s->map, s->mapsize*sizeof(Pte*));
if(s->map != s->ssegmap)
free(s->map);
s->map = map;
s->mapsize = mapsize;
}
s->top = newtop;
s->size = newsize;
qunlock(s);
return 0;
}
/*
* called with s locked
*/
ulong
mcountseg(Segment *s)
{
Pte **pte, **emap;
Page **pg, **pe;
ulong pages;
if((s->type&SG_TYPE) == SG_PHYSICAL)
return 0;
pages = 0;
emap = &s->map[s->mapsize];
for(pte = s->map; pte < emap; pte++){
if(*pte == nil)
continue;
pe = (*pte)->last;
for(pg = (*pte)->first; pg <= pe; pg++)
if(!pagedout(*pg))
pages++;
}
return pages;
}
/*
* called with s locked
*/
void
mfreeseg(Segment *s, uintptr start, ulong pages)
{
uintptr off;
Pte **pte, **emap;
Page **pg, **pe;
if(pages == 0)
return;
if((s->type&SG_TYPE) == SG_PHYSICAL)
return;
/*
* we have to make sure other processors flush the
* entry from their TLBs before the page is freed.
*/
if(s->ref > 1)
procflushseg(s);
off = start-s->base;
pte = &s->map[off/PTEMAPMEM];
off = (off&(PTEMAPMEM-1))/BY2PG;
for(emap = &s->map[s->mapsize]; pte < emap; pte++, off = 0) {
if(*pte == nil) {
off = PTEPERTAB - off;
if(off >= pages)
return;
pages -= off;
continue;
}
pg = &(*pte)->pages[off];
for(pe = &(*pte)->pages[PTEPERTAB]; pg < pe; pg++) {
if(*pg != nil){
putpage(*pg);
*pg = nil;
}
if(--pages == 0)
return;
}
}
}
Segment*
isoverlap(Proc *p, uintptr va, uintptr len)
{
int i;
Segment *ns;
uintptr newtop;
newtop = va+len;
for(i = 0; i < NSEG; i++) {
ns = p->seg[i];
if(ns == nil)
continue;
if((newtop > ns->base && newtop <= ns->top) ||
(va >= ns->base && va < ns->top))
return ns;
}
return nil;
}
int
addphysseg(Physseg* new)
{
Physseg *ps;
/*
* Check not already entered and there is room
* for a new entry and the terminating null entry.
*/
lock(&physseglock);
for(ps = physseg; ps->name; ps++){
if(strcmp(ps->name, new->name) == 0){
unlock(&physseglock);
return -1;
}
}
if(ps-physseg >= nelem(physseg)-2){
unlock(&physseglock);
return -1;
}
*ps = *new;
unlock(&physseglock);
return 0;
}
int
isphysseg(char *name)
{
Physseg *ps;
int rv = 0;
lock(&physseglock);
for(ps = physseg; ps->name; ps++){
if(strcmp(ps->name, name) == 0){
rv = 1;
break;
}
}
unlock(&physseglock);
return rv;
}
uintptr
segattach(Proc *p, ulong attr, char *name, uintptr va, uintptr len)
{
int sno;
Segment *s, *os;
Physseg *ps;
if(va != 0 && va >= USTKTOP)
error(Ebadarg);
validaddr((uintptr)name, 1, 0);
vmemchr(name, 0, ~0);
for(sno = 0; sno < NSEG; sno++)
if(p->seg[sno] == nil && sno != ESEG)
break;
if(sno == NSEG)
error(Enovmem);
/*
* first look for a global segment with the
* same name
*/
if(_globalsegattach != nil){
s = (*_globalsegattach)(p, name);
if(s != nil){
p->seg[sno] = s;
return s->base;
}
}
/* round up va+len */
len += va & (BY2PG-1);
len = PGROUND(len);
if(len == 0)
error(Ebadarg);
/*
* Find a hole in the address space.
* Starting at the lowest possible stack address - len,
* check for an overlapping segment, and repeat at the
* base of that segment - len until either a hole is found
* or the address space is exhausted. Ensure that we don't
* map the zero page.
*/
if(va == 0) {
for (os = p->seg[SSEG]; os != nil; os = isoverlap(p, va, len)) {
va = os->base;
if(len >= va)
error(Enovmem);
va -= len;
}
}
va &= ~(BY2PG-1);
if(va == 0 || (va+len) > USTKTOP || (va+len) < va)
error(Ebadarg);
if(isoverlap(p, va, len) != nil)
error(Esoverlap);
for(ps = physseg; ps->name; ps++)
if(strcmp(name, ps->name) == 0)
goto found;
error(Ebadarg);
found:
if(len > ps->size)
error(Enovmem);
attr &= ~SG_TYPE; /* Turn off what is not allowed */
attr |= ps->attr; /* Copy in defaults */
s = newseg(attr, va, len/BY2PG);
s->pseg = ps;
p->seg[sno] = s;
return va;
}
uintptr
syssegflush(va_list list)
{
uintptr from, to, off, len;
Segment *s;
Pte *pte;
Page **pg, **pe;
from = va_arg(list, uintptr);
to = va_arg(list, ulong);
to += from;
to = PGROUND(to);
from &= ~(BY2PG-1);
if(to < from)
error(Ebadarg);
while(from < to) {
s = seg(up, from, 1);
if(s == nil)
error(Ebadarg);
s->flushme = 1;
more:
len = (s->top < to ? s->top : to) - from;
off = from-s->base;
pte = s->map[off/PTEMAPMEM];
off &= PTEMAPMEM-1;
if(off+len > PTEMAPMEM)
len = PTEMAPMEM-off;
if(pte != nil) {
pg = &pte->pages[off/BY2PG];
pe = pg + len/BY2PG;
while(pg < pe) {
if(!pagedout(*pg))
(*pg)->txtflush = ~0;
pg++;
}
}
from += len;
if(from < to && from < s->top)
goto more;
qunlock(s);
}
flushmmu();
return 0;
}
void
segclock(uintptr pc)
{
Segment *s;
s = up->seg[TSEG];
if(s == nil || s->profile == nil)
return;
s->profile[0] += TK2MS(1);
if(pc >= s->base && pc < s->top) {
pc -= s->base;
s->profile[pc>>LRESPROF] += TK2MS(1);
}
}
Segment*
txt2data(Segment *s)
{
Segment *ps;
ps = newseg(SG_DATA, s->base, s->size);
ps->image = s->image;
incref(ps->image);
ps->fstart = s->fstart;
ps->flen = s->flen;
ps->flushme = 1;
qunlock(s);
putseg(s);
qlock(ps);
return ps;
}
Segment*
data2txt(Segment *s)
{
Segment *ps;
ps = newseg(SG_TEXT, s->base, s->size);
ps->image = s->image;
incref(ps->image);
ps->fstart = s->fstart;
ps->flen = s->flen;
ps->flushme = 1;
return ps;
}