page.c 11 KB

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  1. #include "u.h"
  2. #include "../port/lib.h"
  3. #include "mem.h"
  4. #include "dat.h"
  5. #include "fns.h"
  6. #include "../port/error.h"
  7. #define pghash(daddr) palloc.hash[(daddr>>PGSHIFT)&(PGHSIZE-1)]
  8. struct Palloc palloc;
  9. void
  10. pageinit(void)
  11. {
  12. int color, i, j;
  13. Page *p;
  14. Pallocmem *pm;
  15. ulong m, np, k, vkb, pkb;
  16. np = 0;
  17. for(i=0; i<nelem(palloc.mem); i++){
  18. pm = &palloc.mem[i];
  19. np += pm->npage;
  20. }
  21. palloc.pages = xalloc(np*sizeof(Page));
  22. if(palloc.pages == 0)
  23. panic("pageinit");
  24. color = 0;
  25. palloc.head = palloc.pages;
  26. p = palloc.head;
  27. for(i=0; i<nelem(palloc.mem); i++){
  28. pm = &palloc.mem[i];
  29. for(j=0; j<pm->npage; j++){
  30. p->prev = p-1;
  31. p->next = p+1;
  32. p->pa = pm->base+j*BY2PG;
  33. p->color = color;
  34. palloc.freecount++;
  35. color = (color+1)%NCOLOR;
  36. p++;
  37. }
  38. }
  39. palloc.tail = p - 1;
  40. palloc.head->prev = 0;
  41. palloc.tail->next = 0;
  42. palloc.user = p - palloc.pages;
  43. pkb = palloc.user*BY2PG/1024;
  44. vkb = pkb + (conf.nswap*BY2PG)/1024;
  45. /* Paging numbers */
  46. swapalloc.highwater = (palloc.user*5)/100;
  47. swapalloc.headroom = swapalloc.highwater + (swapalloc.highwater/4);
  48. m = 0;
  49. for(i=0; i<nelem(conf.mem); i++)
  50. if(conf.mem[i].npage)
  51. m += conf.mem[i].npage*BY2PG;
  52. k = PGROUND(end - (char*)KTZERO);
  53. print("%ldM memory: ", (m+k+1024*1024-1)/(1024*1024));
  54. print("%ldM kernel data, ", (m+k-pkb*1024+1024*1024-1)/(1024*1024));
  55. print("%ldM user, ", pkb/1024);
  56. print("%ldM swap\n", vkb/1024);
  57. }
  58. static void
  59. pageunchain(Page *p)
  60. {
  61. if(canlock(&palloc))
  62. panic("pageunchain (palloc %p)", &palloc);
  63. if(p->prev)
  64. p->prev->next = p->next;
  65. else
  66. palloc.head = p->next;
  67. if(p->next)
  68. p->next->prev = p->prev;
  69. else
  70. palloc.tail = p->prev;
  71. p->prev = p->next = nil;
  72. palloc.freecount--;
  73. }
  74. void
  75. pagechaintail(Page *p)
  76. {
  77. if(canlock(&palloc))
  78. panic("pagechaintail");
  79. if(palloc.tail) {
  80. p->prev = palloc.tail;
  81. palloc.tail->next = p;
  82. }
  83. else {
  84. palloc.head = p;
  85. p->prev = 0;
  86. }
  87. palloc.tail = p;
  88. p->next = 0;
  89. palloc.freecount++;
  90. }
  91. void
  92. pagechainhead(Page *p)
  93. {
  94. if(canlock(&palloc))
  95. panic("pagechainhead");
  96. if(palloc.head) {
  97. p->next = palloc.head;
  98. palloc.head->prev = p;
  99. }
  100. else {
  101. palloc.tail = p;
  102. p->next = 0;
  103. }
  104. palloc.head = p;
  105. p->prev = 0;
  106. palloc.freecount++;
  107. }
  108. Page*
  109. newpage(int clear, Segment **s, ulong va)
  110. {
  111. Page *p;
  112. KMap *k;
  113. uchar ct;
  114. int i, hw, dontalloc, color;
  115. lock(&palloc);
  116. color = getpgcolor(va);
  117. hw = swapalloc.highwater;
  118. for(;;) {
  119. if(palloc.freecount > hw)
  120. break;
  121. if(up->kp && palloc.freecount > 0)
  122. break;
  123. unlock(&palloc);
  124. dontalloc = 0;
  125. if(s && *s) {
  126. qunlock(&((*s)->lk));
  127. *s = 0;
  128. dontalloc = 1;
  129. }
  130. qlock(&palloc.pwait); /* Hold memory requesters here */
  131. while(waserror()) /* Ignore interrupts */
  132. ;
  133. kickpager();
  134. tsleep(&palloc.r, ispages, 0, 1000);
  135. poperror();
  136. qunlock(&palloc.pwait);
  137. /*
  138. * If called from fault and we lost the segment from
  139. * underneath don't waste time allocating and freeing
  140. * a page. Fault will call newpage again when it has
  141. * reacquired the segment locks
  142. */
  143. if(dontalloc)
  144. return 0;
  145. lock(&palloc);
  146. }
  147. /* First try for our colour */
  148. for(p = palloc.head; p; p = p->next)
  149. if(p->color == color)
  150. break;
  151. ct = PG_NOFLUSH;
  152. if(p == 0) {
  153. p = palloc.head;
  154. p->color = color;
  155. ct = PG_NEWCOL;
  156. }
  157. pageunchain(p);
  158. lock(p);
  159. if(p->ref != 0)
  160. panic("newpage");
  161. uncachepage(p);
  162. p->ref++;
  163. p->va = va;
  164. p->modref = 0;
  165. for(i = 0; i < MAXMACH; i++)
  166. p->cachectl[i] = ct;
  167. unlock(p);
  168. unlock(&palloc);
  169. if(clear) {
  170. k = kmap(p);
  171. memset((void*)VA(k), 0, BY2PG);
  172. kunmap(k);
  173. }
  174. return p;
  175. }
  176. int
  177. ispages(void*)
  178. {
  179. return palloc.freecount >= swapalloc.highwater;
  180. }
  181. void
  182. putpage(Page *p)
  183. {
  184. if(onswap(p)) {
  185. putswap(p);
  186. return;
  187. }
  188. lock(&palloc);
  189. lock(p);
  190. if(p->ref == 0)
  191. panic("putpage");
  192. if(--p->ref > 0) {
  193. unlock(p);
  194. unlock(&palloc);
  195. return;
  196. }
  197. if(p->image && p->image != &swapimage)
  198. pagechaintail(p);
  199. else
  200. pagechainhead(p);
  201. if(palloc.r.p != 0)
  202. wakeup(&palloc.r);
  203. unlock(p);
  204. unlock(&palloc);
  205. }
  206. Page*
  207. auxpage(void)
  208. {
  209. Page *p;
  210. lock(&palloc);
  211. p = palloc.head;
  212. if(palloc.freecount < swapalloc.highwater) {
  213. unlock(&palloc);
  214. return 0;
  215. }
  216. pageunchain(p);
  217. lock(p);
  218. if(p->ref != 0)
  219. panic("auxpage");
  220. p->ref++;
  221. uncachepage(p);
  222. unlock(p);
  223. unlock(&palloc);
  224. return p;
  225. }
  226. static int dupretries = 15000;
  227. int
  228. duppage(Page *p) /* Always call with p locked */
  229. {
  230. Page *np;
  231. int color;
  232. int retries;
  233. retries = 0;
  234. retry:
  235. if(retries++ > dupretries){
  236. print("duppage %d, up %p\n", retries, up);
  237. dupretries += 100;
  238. if(dupretries > 100000)
  239. panic("duppage\n");
  240. uncachepage(p);
  241. return 1;
  242. }
  243. /* don't dup pages with no image */
  244. if(p->ref == 0 || p->image == nil || p->image->notext)
  245. return 0;
  246. /*
  247. * normal lock ordering is to call
  248. * lock(&palloc) before lock(p).
  249. * To avoid deadlock, we have to drop
  250. * our locks and try again.
  251. */
  252. if(!canlock(&palloc)){
  253. unlock(p);
  254. if(up)
  255. sched();
  256. lock(p);
  257. goto retry;
  258. }
  259. /* No freelist cache when memory is very low */
  260. if(palloc.freecount < swapalloc.highwater) {
  261. unlock(&palloc);
  262. uncachepage(p);
  263. return 1;
  264. }
  265. color = getpgcolor(p->va);
  266. for(np = palloc.head; np; np = np->next)
  267. if(np->color == color)
  268. break;
  269. /* No page of the correct color */
  270. if(np == 0) {
  271. unlock(&palloc);
  272. uncachepage(p);
  273. return 1;
  274. }
  275. pageunchain(np);
  276. pagechaintail(np);
  277. /*
  278. * XXX - here's a bug? - np is on the freelist but it's not really free.
  279. * when we unlock palloc someone else can come in, decide to
  280. * use np, and then try to lock it. they succeed after we've
  281. * run copypage and cachepage and unlock(np). then what?
  282. * they call pageunchain before locking(np), so it's removed
  283. * from the freelist, but still in the cache because of
  284. * cachepage below. if someone else looks in the cache
  285. * before they remove it, the page will have a nonzero ref
  286. * once they finally lock(np).
  287. */
  288. lock(np);
  289. unlock(&palloc);
  290. /* Cache the new version */
  291. uncachepage(np);
  292. np->va = p->va;
  293. np->daddr = p->daddr;
  294. copypage(p, np);
  295. cachepage(np, p->image);
  296. unlock(np);
  297. uncachepage(p);
  298. return 0;
  299. }
  300. void
  301. copypage(Page *f, Page *t)
  302. {
  303. KMap *ks, *kd;
  304. ks = kmap(f);
  305. kd = kmap(t);
  306. memmove((void*)VA(kd), (void*)VA(ks), BY2PG);
  307. kunmap(ks);
  308. kunmap(kd);
  309. }
  310. void
  311. uncachepage(Page *p) /* Always called with a locked page */
  312. {
  313. Page **l, *f;
  314. if(p->image == 0)
  315. return;
  316. lock(&palloc.hashlock);
  317. l = &pghash(p->daddr);
  318. for(f = *l; f; f = f->hash) {
  319. if(f == p) {
  320. *l = p->hash;
  321. break;
  322. }
  323. l = &f->hash;
  324. }
  325. unlock(&palloc.hashlock);
  326. putimage(p->image);
  327. p->image = 0;
  328. p->daddr = 0;
  329. }
  330. void
  331. cachepage(Page *p, Image *i)
  332. {
  333. Page **l;
  334. /* If this ever happens it should be fixed by calling
  335. * uncachepage instead of panic. I think there is a race
  336. * with pio in which this can happen. Calling uncachepage is
  337. * correct - I just wanted to see if we got here.
  338. */
  339. if(p->image)
  340. panic("cachepage");
  341. incref(i);
  342. lock(&palloc.hashlock);
  343. p->image = i;
  344. l = &pghash(p->daddr);
  345. p->hash = *l;
  346. *l = p;
  347. unlock(&palloc.hashlock);
  348. }
  349. void
  350. cachedel(Image *i, ulong daddr)
  351. {
  352. Page *f, **l;
  353. lock(&palloc.hashlock);
  354. l = &pghash(daddr);
  355. for(f = *l; f; f = f->hash) {
  356. if(f->image == i && f->daddr == daddr) {
  357. lock(f);
  358. if(f->image == i && f->daddr == daddr){
  359. *l = f->hash;
  360. putimage(f->image);
  361. f->image = 0;
  362. f->daddr = 0;
  363. }
  364. unlock(f);
  365. break;
  366. }
  367. l = &f->hash;
  368. }
  369. unlock(&palloc.hashlock);
  370. }
  371. Page *
  372. lookpage(Image *i, ulong daddr)
  373. {
  374. Page *f;
  375. lock(&palloc.hashlock);
  376. for(f = pghash(daddr); f; f = f->hash) {
  377. if(f->image == i && f->daddr == daddr) {
  378. unlock(&palloc.hashlock);
  379. lock(&palloc);
  380. lock(f);
  381. if(f->image != i || f->daddr != daddr) {
  382. unlock(f);
  383. unlock(&palloc);
  384. return 0;
  385. }
  386. if(++f->ref == 1)
  387. pageunchain(f);
  388. unlock(&palloc);
  389. unlock(f);
  390. return f;
  391. }
  392. }
  393. unlock(&palloc.hashlock);
  394. return 0;
  395. }
  396. Pte*
  397. ptecpy(Pte *old)
  398. {
  399. Pte *new;
  400. Page **src, **dst;
  401. new = ptealloc();
  402. dst = &new->pages[old->first-old->pages];
  403. new->first = dst;
  404. for(src = old->first; src <= old->last; src++, dst++)
  405. if(*src) {
  406. if(onswap(*src))
  407. dupswap(*src);
  408. else {
  409. lock(*src);
  410. (*src)->ref++;
  411. unlock(*src);
  412. }
  413. new->last = dst;
  414. *dst = *src;
  415. }
  416. return new;
  417. }
  418. Pte*
  419. ptealloc(void)
  420. {
  421. Pte *new;
  422. new = smalloc(sizeof(Pte));
  423. new->first = &new->pages[PTEPERTAB];
  424. new->last = new->pages;
  425. return new;
  426. }
  427. void
  428. freepte(Segment *s, Pte *p)
  429. {
  430. int ref;
  431. void (*fn)(Page*);
  432. Page *pt, **pg, **ptop;
  433. switch(s->type&SG_TYPE) {
  434. case SG_PHYSICAL:
  435. fn = s->pseg->pgfree;
  436. ptop = &p->pages[PTEPERTAB];
  437. if(fn) {
  438. for(pg = p->pages; pg < ptop; pg++) {
  439. if(*pg == 0)
  440. continue;
  441. (*fn)(*pg);
  442. *pg = 0;
  443. }
  444. break;
  445. }
  446. for(pg = p->pages; pg < ptop; pg++) {
  447. pt = *pg;
  448. if(pt == 0)
  449. continue;
  450. lock(pt);
  451. ref = --pt->ref;
  452. unlock(pt);
  453. if(ref == 0)
  454. free(pt);
  455. }
  456. break;
  457. default:
  458. for(pg = p->first; pg <= p->last; pg++)
  459. if(*pg) {
  460. putpage(*pg);
  461. *pg = 0;
  462. }
  463. }
  464. free(p);
  465. }
  466. ulong
  467. pagenumber(Page *p)
  468. {
  469. return p-palloc.pages;
  470. }
  471. void
  472. checkpagerefs(void)
  473. {
  474. int s;
  475. ulong i, np, nwrong;
  476. ulong *ref;
  477. np = palloc.user;
  478. ref = malloc(np*sizeof ref[0]);
  479. if(ref == nil){
  480. print("checkpagerefs: out of memory\n");
  481. return;
  482. }
  483. /*
  484. * This may not be exact if there are other processes
  485. * holding refs to pages on their stacks. The hope is
  486. * that if you run it on a quiescent system it will still
  487. * be useful.
  488. */
  489. s = splhi();
  490. lock(&palloc);
  491. countpagerefs(ref, 0);
  492. portcountpagerefs(ref, 0);
  493. nwrong = 0;
  494. for(i=0; i<np; i++){
  495. if(palloc.pages[i].ref != ref[i]){
  496. iprint("page %#.8lux ref %d actual %lud\n",
  497. palloc.pages[i].pa, palloc.pages[i].ref, ref[i]);
  498. ref[i] = 1;
  499. nwrong++;
  500. }else
  501. ref[i] = 0;
  502. }
  503. countpagerefs(ref, 1);
  504. portcountpagerefs(ref, 1);
  505. iprint("%lud mistakes found\n", nwrong);
  506. unlock(&palloc);
  507. splx(s);
  508. }
  509. void
  510. portcountpagerefs(ulong *ref, int print)
  511. {
  512. ulong i, j, k, ns, n;
  513. Page **pg, *entry;
  514. Proc *p;
  515. Pte *pte;
  516. Segment *s;
  517. /*
  518. * Pages in segments. s->mark avoids double-counting.
  519. */
  520. n = 0;
  521. ns = 0;
  522. for(i=0; i<conf.nproc; i++){
  523. p = proctab(i);
  524. for(j=0; j<NSEG; j++){
  525. s = p->seg[j];
  526. if(s)
  527. s->mark = 0;
  528. }
  529. }
  530. for(i=0; i<conf.nproc; i++){
  531. p = proctab(i);
  532. for(j=0; j<NSEG; j++){
  533. s = p->seg[j];
  534. if(s == nil || s->mark++)
  535. continue;
  536. ns++;
  537. for(k=0; k<s->mapsize; k++){
  538. pte = s->map[k];
  539. if(pte == nil)
  540. continue;
  541. for(pg = pte->first; pg <= pte->last; pg++){
  542. entry = *pg;
  543. if(pagedout(entry))
  544. continue;
  545. if(print){
  546. if(ref[pagenumber(entry)])
  547. iprint("page %#.8lux in segment %#p\n", entry->pa, s);
  548. continue;
  549. }
  550. if(ref[pagenumber(entry)]++ == 0)
  551. n++;
  552. }
  553. }
  554. }
  555. }
  556. if(!print){
  557. iprint("%lud pages in %lud segments\n", n, ns);
  558. for(i=0; i<conf.nproc; i++){
  559. p = proctab(i);
  560. for(j=0; j<NSEG; j++){
  561. s = p->seg[j];
  562. if(s == nil)
  563. continue;
  564. if(s->ref != s->mark){
  565. iprint("segment %#p (used by proc %lud pid %lud) has bad ref count %lud actual %lud\n",
  566. s, i, p->pid, s->ref, s->mark);
  567. }
  568. }
  569. }
  570. }
  571. }