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1/* See COPYRIGHT for copyright information. */
2
3#include <inc/x86.h>
4#include <inc/mmu.h>
5#include <inc/error.h>
6#include <inc/string.h>
7#include <inc/assert.h>
8
9#include <kern/pmap.h>
10#include <kern/kclock.h>
11
12// These variables are set by i386_detect_memory()
13size_t npages;			// Amount of physical memory (in pages)
14static size_t npages_basemem;	// Amount of base memory (in pages)
15
16// These variables are set in mem_init()
17pde_t *kern_pgdir;		// Kernel's initial page directory
18struct PageInfo *pages;		// Physical page state array
19static struct PageInfo *page_free_list;	// Free list of physical pages
20
21
22// --------------------------------------------------------------
23// Detect machine's physical memory setup.
24// --------------------------------------------------------------
25
26static int
27nvram_read(int r)
28{
29	return mc146818_read(r) | (mc146818_read(r + 1) << 8);
30}
31
32static void
33i386_detect_memory(void)
34{
35	size_t basemem, extmem, ext16mem, totalmem;
36
37	// Use CMOS calls to measure available base & extended memory.
38	// (CMOS calls return results in kilobytes.)
39	basemem = nvram_read(NVRAM_BASELO);
40	extmem = nvram_read(NVRAM_EXTLO);
41	ext16mem = nvram_read(NVRAM_EXT16LO) * 64;
42
43	// Calculate the number of physical pages available in both base
44	// and extended memory.
45	if (ext16mem)
46		totalmem = 16 * 1024 + ext16mem;
47	else if (extmem)
48		totalmem = 1 * 1024 + extmem;
49	else
50		totalmem = basemem;
51
52	npages = totalmem / (PGSIZE / 1024);
53	npages_basemem = basemem / (PGSIZE / 1024);
54
55	cprintf("Physical memory: %uK available, base = %uK, extended = %uK\n",
56		totalmem, basemem, totalmem - basemem);
57}
58
59
60// --------------------------------------------------------------
61// Set up memory mappings above UTOP.
62// --------------------------------------------------------------
63
64static void boot_map_region(pde_t *pgdir, uintptr_t va, size_t size, physaddr_t pa, int perm);
65static void check_page_free_list(bool only_low_memory);
66static void check_page_alloc(void);
67static void check_kern_pgdir(void);
68static physaddr_t check_va2pa(pde_t *pgdir, uintptr_t va);
69static void check_page(void);
70static void check_page_installed_pgdir(void);
71
72// This simple physical memory allocator is used only while JOS is setting
73// up its virtual memory system.  page_alloc() is the real allocator.
74//
75// If n>0, allocates enough pages of contiguous physical memory to hold 'n'
76// bytes.  Doesn't initialize the memory.  Returns a kernel virtual address.
77//
78// If n==0, returns the address of the next free page without allocating
79// anything.
80//
81// If we're out of memory, boot_alloc should panic.
82// This function may ONLY be used during initialization,
83// before the page_free_list list has been set up.
84static void *
85boot_alloc(uint32_t n)
86{
87	static char *nextfree;	// virtual address of next byte of free memory
88	char *result;
89
90	// Initialize nextfree if this is the first time.
91	// 'end' is a magic symbol automatically generated by the linker,
92	// which points to the end of the kernel's bss segment:
93	// the first virtual address that the linker did *not* assign
94	// to any kernel code or global variables.
95	if (!nextfree) {
96		extern char end[];
97		nextfree = ROUNDUP((char *) end, PGSIZE);
98	}
99
100	// Allocate a chunk large enough to hold 'n' bytes, then update
101	// nextfree.  Make sure nextfree is kept aligned
102	// to a multiple of PGSIZE.
103	//
104	// LAB 2: Your code here.
105	if (n>0) {
106	result = nextfree;
107	nextfree += ROUNDUP (n, PGSIZE);
108	if ((uintptr_t)nextfree >= KERNBASE+4*1024*1024) panic("NEMAME PAMAT NA ALLOCOVANIE"); //KERNBASE(0xF0000000)+ 4*1024*1024 //uintptr - datovy typ ktory reprezentuje virtualne adresy (int/types.h)   
109}
110else {
111result = nextfree; 
112}
113	return result;
114}
115
116// Set up a two-level page table:
117//    kern_pgdir is its linear (virtual) address of the root
118//
119// This function only sets up the kernel part of the address space
120// (ie. addresses >= UTOP).  The user part of the address space
121// will be setup later.
122//
123// From UTOP to ULIM, the user is allowed to read but not write.
124// Above ULIM the user cannot read or write.
125void
126mem_init(void)
127{
128	uint32_t cr0;
129	size_t n;
130
131	// Find out how much memory the machine has (npages & npages_basemem).
132	i386_detect_memory();
133
134	// Remove this line when you're ready to test this function.
135	//panic("mem_init: This function is not finished\n");
136
137	//////////////////////////////////////////////////////////////////////
138	// create initial page directory.
139	kern_pgdir = (pde_t *) boot_alloc(PGSIZE);
140	memset(kern_pgdir, 0, PGSIZE);
141
142	//////////////////////////////////////////////////////////////////////
143	// Recursively insert PD in itself as a page table, to form
144	// a virtual page table at virtual address UVPT.
145	// (For now, you don't have understand the greater purpose of the
146	// following line.)
147
148	// Permissions: kernel R, user R
149	kern_pgdir[PDX(UVPT)] = PADDR(kern_pgdir) | PTE_U | PTE_P;
150
151	//////////////////////////////////////////////////////////////////////
152	// Allocate an array of npages 'struct PageInfo's and store it in 'pages'.
153	// The kernel uses this array to keep track of physical pages: for
154	// each physical page, there is a corresponding struct PageInfo in this
155	// array.  'npages' is the number of physical pages in memory.  Use memset
156	// to initialize all fields of each struct PageInfo to 0.
157	// Your code goes here:
158
159	pages = (struct PageInfo*) boot_alloc(sizeof(struct PageInfo)* npages);
160	memset (pages, 0,sizeof(struct PageInfo)* npages); //memset (*ptr, co, velkost) //ptr - smernik odkial mame zacat
161	
162	//////////////////////////////////////////////////////////////////////
163	// Now that we've allocated the initial kernel data structures, we set
164	// up the list of free physical pages. Once we've done so, all further
165	// memory management will go through the page_* functions. In
166	// particular, we can now map memory using boot_map_region
167	// or page_insert
168	page_init();
169
170	check_page_free_list(1);
171	check_page_alloc();
172	check_page();
173
174	//////////////////////////////////////////////////////////////////////
175	// Now we set up virtual memory
176
177	//////////////////////////////////////////////////////////////////////
178	// Map 'pages' read-only by the user at linear address UPAGES
179	// Permissions:
180	//    - the new image at UPAGES -- kernel R, user R
181	//      (ie. perm = PTE_U | PTE_P)
182	//    - pages itself -- kernel RW, user NONE
183	// Your code goes here:
184
185	
186
187	//////////////////////////////////////////////////////////////////////
188	// Use the physical memory that 'bootstack' refers to as the kernel
189	// stack.  The kernel stack grows down from virtual address KSTACKTOP.
190	// We consider the entire range from [KSTACKTOP-PTSIZE, KSTACKTOP)
191	// to be the kernel stack, but break this into two pieces:
192	//     * [KSTACKTOP-KSTKSIZE, KSTACKTOP) -- backed by physical memory
193	//     * [KSTACKTOP-PTSIZE, KSTACKTOP-KSTKSIZE) -- not backed; so if
194	//       the kernel overflows its stack, it will fault rather than
195	//       overwrite memory.  Known as a "guard page".
196	//     Permissions: kernel RW, user NONE
197	// Your code goes here:
198
199	//////////////////////////////////////////////////////////////////////
200	// Map all of physical memory at KERNBASE.
201	// Ie.  the VA range [KERNBASE, 2^32) should map to
202	//      the PA range [0, 2^32 - KERNBASE)
203	// We might not have 2^32 - KERNBASE bytes of physical memory, but
204	// we just set up the mapping anyway.
205	// Permissions: kernel RW, user NONE
206	// Your code goes here:
207
208	// Check that the initial page directory has been set up correctly.
209	check_kern_pgdir();
210
211	// Switch from the minimal entry page directory to the full kern_pgdir
212	// page table we just created.	Our instruction pointer should be
213	// somewhere between KERNBASE and KERNBASE+4MB right now, which is
214	// mapped the same way by both page tables.
215	//
216	// If the machine reboots at this point, you've probably set up your
217	// kern_pgdir wrong.
218	lcr3(PADDR(kern_pgdir));
219
220	check_page_free_list(0);
221
222	// entry.S set the really important flags in cr0 (including enabling
223	// paging).  Here we configure the rest of the flags that we care about.
224	cr0 = rcr0();
225	cr0 |= CR0_PE|CR0_PG|CR0_AM|CR0_WP|CR0_NE|CR0_MP;
226	cr0 &= ~(CR0_TS|CR0_EM);
227	lcr0(cr0);
228
229	// Some more checks, only possible after kern_pgdir is installed.
230	check_page_installed_pgdir();
231}
232
233// --------------------------------------------------------------
234// Tracking of physical pages.
235// The 'pages' array has one 'struct PageInfo' entry per physical page.
236// Pages are reference counted, and free pages are kept on a linked list.
237// --------------------------------------------------------------
238
239//
240// Initialize page structure and memory free list.
241// After this is done, NEVER use boot_alloc again.  ONLY use the page
242// allocator functions below to allocate and deallocate physical
243// memory via the page_free_list.
244//
245void
246page_init(void)
247{
248	// The example code here marks all physical pages as free.
249	// However this is not truly the case.  What memory is free?
250	//  1) Mark physical page 0 as in use.
251	//     This way we preserve the real-mode IDT and BIOS structures
252	//     in case we ever need them.  (Currently we don't, but...)
253	//  2) The rest of base memory, [PGSIZE, npages_basemem * PGSIZE)
254	//     is free.
255	//  3) Then comes the IO hole [IOPHYSMEM, EXTPHYSMEM), which must
256	//     never be allocated.
257	//  4) Then extended memory [EXTPHYSMEM, ...).
258	//     Some of it is in use, some is free. Where is the kernel
259	//     in physical memory?  Which pages are already in use for
260	//     page tables and other data structures?
261	//
262	// Change the code to reflect this.
263	// NB: DO NOT actually touch the physical memory corresponding to
264	// free pages!
265	size_t i;
266// 2bod
267	for (i = 1; i < npages_basemem; i++){ //<PGSIZE; upages_basemem *PGsize) ukazuje na volne stranky
268	pages[i].pp_ref = 0;
269	pages[i].pp_link = page_free_list; //nastavujeme na volny page
270	page_free_list = &pages[i];	
271}
272
273//3 bod neriesime pretoze basemem konci kde zacina IOPHYSMEM
274
275// 4 bod
276	for(i=PGNUM(PADDR(boot_alloc(0))); i < npages; i++){ //(i=PGNUM(PADDR(boot_allpc(0))) cislo stranky odkial je volna pamat
277	pages[i].pp_ref = 0;
278	pages[i].pp_link = page_free_list; //nastavujeme na volny page
279	page_free_list = &pages[i];
280}	
281
282
283// 1bod
284	for (i = 0; i < npages; i++) {
285		pages[i].pp_ref = 0; //pp_ref - nachadza sa v strukture pageInfo, pocet smernikov v ramke na stranku (inc/mamlayout.h 175 riadok)
286		pages[i].pp_link = page_free_list;
287		page_free_list = &pages[i];
288	}
289
290}
291
292//
293// Allocates a physical page.  If (alloc_flags & ALLOC_ZERO), fills the entire
294// returned physical page with '\0' bytes.  Does NOT increment the reference
295// count of the page - the caller must do these if necessary (either explicitly
296// or via page_insert).
297//
298// Be sure to set the pp_link field of the allocated page to NULL so
299// page_free can check for double-free bugs.
300//
301// Returns NULL if out of free memory.
302//
303// Hint: use page2kva and memset
304
305//doplname funkciu
306struct PageInfo *
307page_alloc(int alloc_flags)
308{
309	if(page_free_list){
310	struct PageInfo *result = page_free_list;
311	page_free_list = page_free_list -> pp_link; //pp_link to je next
312
313	if(alloc_flags & ALLOC_ZERO){
314	memset(page2kva(result),'\0', PGSIZE); //page2kva - virtualna adresa
315	}
316	result -> pp_link = NULL;
317	return result;
318	}
319	return NULL;
320}
321
322//
323// Return a page to the free list.
324// (This function should only be called when pp->pp_ref reaches 0.)
325//
326void
327page_free(struct PageInfo *pp)
328{
329	// Fill this function in
330	// Hint: You may want to panic if pp->pp_ref is nonzero or
331	// pp->pp_link is not NULL.
332	pp->pp_link = page_free_list;
333	page_free_list = pp;
334
335}
336
337//
338// Decrement the reference count on a page,
339// freeing it if there are no more refs.
340//
341void
342page_decref(struct PageInfo* pp)
343{
344	if (--pp->pp_ref == 0)
345		page_free(pp);
346}
347
348// Given 'pgdir', a pointer to a page directory, pgdir_walk returns
349// a pointer to the page table entry (PTE) for linear address 'va'.
350// This requires walking the two-level page table structure.
351//
352// The relevant page table page might not exist yet.
353// If this is true, and create == false, then pgdir_walk returns NULL.
354// Otherwise, pgdir_walk allocates a new page table page with page_alloc.
355//    - If the allocation fails, pgdir_walk returns NULL.
356//    - Otherwise, the new page's reference count is incremented,
357//	the page is cleared,
358//	and pgdir_walk returns a pointer into the new page table page.
359//
360// Hint 1: you can turn a PageInfo * into the physical address of the
361// page it refers to with page2pa() from kern/pmap.h.
362//
363// Hint 2: the x86 MMU checks permission bits in both the page directory
364// and the page table, so it's safe to leave permissions in the page
365// directory more permissive than strictly necessary.
366//
367// Hint 3: look at inc/mmu.h for useful macros that mainipulate page
368// table and page directory entries.
369//
370pte_t *
371pgdir_walk(pde_t *pgdir, const void *va, int create)
372{
373	// Fill this function in
374	return NULL;
375}
376
377//
378// Map [va, va+size) of virtual address space to physical [pa, pa+size)
379// in the page table rooted at pgdir.  Size is a multiple of PGSIZE, and
380// va and pa are both page-aligned.
381// Use permission bits perm|PTE_P for the entries.
382//
383// This function is only intended to set up the ``static'' mappings
384// above UTOP. As such, it should *not* change the pp_ref field on the
385// mapped pages.
386//
387// Hint: the TA solution uses pgdir_walk
388static void
389boot_map_region(pde_t *pgdir, uintptr_t va, size_t size, physaddr_t pa, int perm)
390{
391	// Fill this function in
392}
393
394//
395// Map the physical page 'pp' at virtual address 'va'.
396// The permissions (the low 12 bits) of the page table entry
397// should be set to 'perm|PTE_P'.
398//
399// Requirements
400//   - If there is already a page mapped at 'va', it should be page_remove()d.
401//   - If necessary, on demand, a page table should be allocated and inserted
402//     into 'pgdir'.
403//   - pp->pp_ref should be incremented if the insertion succeeds.
404//   - The TLB must be invalidated if a page was formerly present at 'va'.
405//
406// Corner-case hint: Make sure to consider what happens when the same
407// pp is re-inserted at the same virtual address in the same pgdir.
408// However, try not to distinguish this case in your code, as this
409// frequently leads to subtle bugs; there's an elegant way to handle
410// everything in one code path.
411//
412// RETURNS:
413//   0 on success
414//   -E_NO_MEM, if page table couldn't be allocated
415//
416// Hint: The TA solution is implemented using pgdir_walk, page_remove,
417// and page2pa.
418//
419int
420page_insert(pde_t *pgdir, struct PageInfo *pp, void *va, int perm)
421{
422	// Fill this function in
423	return 0;
424}
425
426//
427// Return the page mapped at virtual address 'va'.
428// If pte_store is not zero, then we store in it the address
429// of the pte for this page.  This is used by page_remove and
430// can be used to verify page permissions for syscall arguments,
431// but should not be used by most callers.
432//
433// Return NULL if there is no page mapped at va.
434//
435// Hint: the TA solution uses pgdir_walk and pa2page.
436//
437struct PageInfo *
438page_lookup(pde_t *pgdir, void *va, pte_t **pte_store)
439{
440	// Fill this function in
441	return NULL;
442}
443
444//
445// Unmaps the physical page at virtual address 'va'.
446// If there is no physical page at that address, silently does nothing.
447//
448// Details:
449//   - The ref count on the physical page should decrement.
450//   - The physical page should be freed if the refcount reaches 0.
451//   - The pg table entry corresponding to 'va' should be set to 0.
452//     (if such a PTE exists)
453//   - The TLB must be invalidated if you remove an entry from
454//     the page table.
455//
456// Hint: The TA solution is implemented using page_lookup,
457// 	tlb_invalidate, and page_decref.
458//
459void
460page_remove(pde_t *pgdir, void *va)
461{
462	// Fill this function in
463}
464
465//
466// Invalidate a TLB entry, but only if the page tables being
467// edited are the ones currently in use by the processor.
468//
469void
470tlb_invalidate(pde_t *pgdir, void *va)
471{
472	// Flush the entry only if we're modifying the current address space.
473	// For now, there is only one address space, so always invalidate.
474	invlpg(va);
475}
476
477
478// --------------------------------------------------------------
479// Checking functions.
480// --------------------------------------------------------------
481
482//
483// Check that the pages on the page_free_list are reasonable.
484//
485static void
486check_page_free_list(bool only_low_memory)
487{
488	struct PageInfo *pp;
489	unsigned pdx_limit = only_low_memory ? 1 : NPDENTRIES;
490	int nfree_basemem = 0, nfree_extmem = 0;
491	char *first_free_page;
492
493	if (!page_free_list)
494		panic("'page_free_list' is a null pointer!");
495
496	if (only_low_memory) {
497		// Move pages with lower addresses first in the free
498		// list, since entry_pgdir does not map all pages.
499		struct PageInfo *pp1, *pp2;
500		struct PageInfo **tp[2] = { &pp1, &pp2 };
501		for (pp = page_free_list; pp; pp = pp->pp_link) {
502			int pagetype = PDX(page2pa(pp)) >= pdx_limit;
503			*tp[pagetype] = pp;
504			tp[pagetype] = &pp->pp_link;
505		}
506		*tp[1] = 0;
507		*tp[0] = pp2;
508		page_free_list = pp1;
509	}
510
511	// if there's a page that shouldn't be on the free list,
512	// try to make sure it eventually causes trouble.
513	for (pp = page_free_list; pp; pp = pp->pp_link)
514		if (PDX(page2pa(pp)) < pdx_limit)
515			memset(page2kva(pp), 0x97, 128);
516
517	first_free_page = (char *) boot_alloc(0);
518	for (pp = page_free_list; pp; pp = pp->pp_link) {
519		// check that we didn't corrupt the free list itself
520		assert(pp >= pages);
521		assert(pp < pages + npages);
522		assert(((char *) pp - (char *) pages) % sizeof(*pp) == 0);
523
524		// check a few pages that shouldn't be on the free list
525		assert(page2pa(pp) != 0);
526		assert(page2pa(pp) != IOPHYSMEM);
527		assert(page2pa(pp) != EXTPHYSMEM - PGSIZE);
528		assert(page2pa(pp) != EXTPHYSMEM);
529		assert(page2pa(pp) < EXTPHYSMEM || (char *) page2kva(pp) >= first_free_page);
530
531		if (page2pa(pp) < EXTPHYSMEM)
532			++nfree_basemem;
533		else
534			++nfree_extmem;
535	}
536
537	assert(nfree_basemem > 0);
538	assert(nfree_extmem > 0);
539
540	cprintf("check_page_free_list() succeeded!\n");
541}
542
543//
544// Check the physical page allocator (page_alloc(), page_free(),
545// and page_init()).
546//
547static void
548check_page_alloc(void)
549{
550	struct PageInfo *pp, *pp0, *pp1, *pp2;
551	int nfree;
552	struct PageInfo *fl;
553	char *c;
554	int i;
555
556	if (!pages)
557		panic("'pages' is a null pointer!");
558
559	// check number of free pages
560	for (pp = page_free_list, nfree = 0; pp; pp = pp->pp_link)
561		++nfree;
562
563	// should be able to allocate three pages
564	pp0 = pp1 = pp2 = 0;
565	assert((pp0 = page_alloc(0)));
566	assert((pp1 = page_alloc(0)));
567	assert((pp2 = page_alloc(0)));
568
569	assert(pp0);
570	assert(pp1 && pp1 != pp0);
571	assert(pp2 && pp2 != pp1 && pp2 != pp0);
572	assert(page2pa(pp0) < npages*PGSIZE);
573	assert(page2pa(pp1) < npages*PGSIZE);
574	assert(page2pa(pp2) < npages*PGSIZE);
575
576	// temporarily steal the rest of the free pages
577	fl = page_free_list;
578	page_free_list = 0;
579
580	// should be no free memory
581	assert(!page_alloc(0));
582
583	// free and re-allocate?
584	page_free(pp0);
585	page_free(pp1);
586	page_free(pp2);
587	pp0 = pp1 = pp2 = 0;
588	assert((pp0 = page_alloc(0)));
589	assert((pp1 = page_alloc(0)));
590	assert((pp2 = page_alloc(0)));
591	assert(pp0);
592	assert(pp1 && pp1 != pp0);
593	assert(pp2 && pp2 != pp1 && pp2 != pp0);
594	assert(!page_alloc(0));
595
596	// test flags
597	memset(page2kva(pp0), 1, PGSIZE);
598	page_free(pp0);
599	assert((pp = page_alloc(ALLOC_ZERO)));
600	assert(pp && pp0 == pp);
601	c = page2kva(pp);
602	for (i = 0; i < PGSIZE; i++)
603		assert(c[i] == 0);
604
605	// give free list back
606	page_free_list = fl;
607
608	// free the pages we took
609	page_free(pp0);
610	page_free(pp1);
611	page_free(pp2);
612
613	// number of free pages should be the same
614	for (pp = page_free_list; pp; pp = pp->pp_link)
615		--nfree;
616	assert(nfree == 0);
617
618	cprintf("check_page_alloc() succeeded!\n");
619}
620
621//
622// Checks that the kernel part of virtual address space
623// has been setup roughly correctly (by mem_init()).
624//
625// This function doesn't test every corner case,
626// but it is a pretty good sanity check.
627//
628
629static void
630check_kern_pgdir(void)
631{
632	uint32_t i, n;
633	pde_t *pgdir;
634
635	pgdir = kern_pgdir;
636
637	// check pages array
638	n = ROUNDUP(npages*sizeof(struct PageInfo), PGSIZE);
639	for (i = 0; i < n; i += PGSIZE)
640		assert(check_va2pa(pgdir, UPAGES + i) == PADDR(pages) + i);
641
642
643	// check phys mem
644	for (i = 0; i < npages * PGSIZE; i += PGSIZE)
645		assert(check_va2pa(pgdir, KERNBASE + i) == i);
646
647	// check kernel stack
648	for (i = 0; i < KSTKSIZE; i += PGSIZE)
649		assert(check_va2pa(pgdir, KSTACKTOP - KSTKSIZE + i) == PADDR(bootstack) + i);
650	assert(check_va2pa(pgdir, KSTACKTOP - PTSIZE) == ~0);
651
652	// check PDE permissions
653	for (i = 0; i < NPDENTRIES; i++) {
654		switch (i) {
655		case PDX(UVPT):
656		case PDX(KSTACKTOP-1):
657		case PDX(UPAGES):
658			assert(pgdir[i] & PTE_P);
659			break;
660		default:
661			if (i >= PDX(KERNBASE)) {
662				assert(pgdir[i] & PTE_P);
663				assert(pgdir[i] & PTE_W);
664			} else
665				assert(pgdir[i] == 0);
666			break;
667		}
668	}
669	cprintf("check_kern_pgdir() succeeded!\n");
670}
671
672// This function returns the physical address of the page containing 'va',
673// defined by the page directory 'pgdir'.  The hardware normally performs
674// this functionality for us!  We define our own version to help check
675// the check_kern_pgdir() function; it shouldn't be used elsewhere.
676
677static physaddr_t
678check_va2pa(pde_t *pgdir, uintptr_t va)
679{
680	pte_t *p;
681
682	pgdir = &pgdir[PDX(va)];
683	if (!(*pgdir & PTE_P))
684		return ~0;
685	p = (pte_t*) KADDR(PTE_ADDR(*pgdir));
686	if (!(p[PTX(va)] & PTE_P))
687		return ~0;
688	return PTE_ADDR(p[PTX(va)]);
689}
690
691
692// check page_insert, page_remove, &c
693static void
694check_page(void)
695{
696	struct PageInfo *pp, *pp0, *pp1, *pp2;
697	struct PageInfo *fl;
698	pte_t *ptep, *ptep1;
699	void *va;
700	int i;
701	extern pde_t entry_pgdir[];
702
703	// should be able to allocate three pages
704	pp0 = pp1 = pp2 = 0;
705	assert((pp0 = page_alloc(0)));
706	assert((pp1 = page_alloc(0)));
707	assert((pp2 = page_alloc(0)));
708
709	assert(pp0);
710	assert(pp1 && pp1 != pp0);
711	assert(pp2 && pp2 != pp1 && pp2 != pp0);
712
713	// temporarily steal the rest of the free pages
714	fl = page_free_list;
715	page_free_list = 0;
716
717	// should be no free memory
718	assert(!page_alloc(0));
719
720	// there is no page allocated at address 0
721	assert(page_lookup(kern_pgdir, (void *) 0x0, &ptep) == NULL);
722
723	// there is no free memory, so we can't allocate a page table
724	assert(page_insert(kern_pgdir, pp1, 0x0, PTE_W) < 0);
725
726	// free pp0 and try again: pp0 should be used for page table
727	page_free(pp0);
728	assert(page_insert(kern_pgdir, pp1, 0x0, PTE_W) == 0);
729	assert(PTE_ADDR(kern_pgdir[0]) == page2pa(pp0));
730	assert(check_va2pa(kern_pgdir, 0x0) == page2pa(pp1));
731	assert(pp1->pp_ref == 1);
732	assert(pp0->pp_ref == 1);
733
734	// should be able to map pp2 at PGSIZE because pp0 is already allocated for page table
735	assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W) == 0);
736	assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp2));
737	assert(pp2->pp_ref == 1);
738
739	// should be no free memory
740	assert(!page_alloc(0));
741
742	// should be able to map pp2 at PGSIZE because it's already there
743	assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W) == 0);
744	assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp2));
745	assert(pp2->pp_ref == 1);
746
747	// pp2 should NOT be on the free list
748	// could happen in ref counts are handled sloppily in page_insert
749	assert(!page_alloc(0));
750
751	// check that pgdir_walk returns a pointer to the pte
752	ptep = (pte_t *) KADDR(PTE_ADDR(kern_pgdir[PDX(PGSIZE)]));
753	assert(pgdir_walk(kern_pgdir, (void*)PGSIZE, 0) == ptep+PTX(PGSIZE));
754
755	// should be able to change permissions too.
756	assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W|PTE_U) == 0);
757	assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp2));
758	assert(pp2->pp_ref == 1);
759	assert(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_U);
760	assert(kern_pgdir[0] & PTE_U);
761
762	// should be able to remap with fewer permissions
763	assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W) == 0);
764	assert(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_W);
765	assert(!(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_U));
766
767	// should not be able to map at PTSIZE because need free page for page table
768	assert(page_insert(kern_pgdir, pp0, (void*) PTSIZE, PTE_W) < 0);
769
770	// insert pp1 at PGSIZE (replacing pp2)
771	assert(page_insert(kern_pgdir, pp1, (void*) PGSIZE, PTE_W) == 0);
772	assert(!(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_U));
773
774	// should have pp1 at both 0 and PGSIZE, pp2 nowhere, ...
775	assert(check_va2pa(kern_pgdir, 0) == page2pa(pp1));
776	assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp1));
777	// ... and ref counts should reflect this
778	assert(pp1->pp_ref == 2);
779	assert(pp2->pp_ref == 0);
780
781	// pp2 should be returned by page_alloc
782	assert((pp = page_alloc(0)) && pp == pp2);
783
784	// unmapping pp1 at 0 should keep pp1 at PGSIZE
785	page_remove(kern_pgdir, 0x0);
786	assert(check_va2pa(kern_pgdir, 0x0) == ~0);
787	assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp1));
788	assert(pp1->pp_ref == 1);
789	assert(pp2->pp_ref == 0);
790
791	// test re-inserting pp1 at PGSIZE
792	assert(page_insert(kern_pgdir, pp1, (void*) PGSIZE, 0) == 0);
793	assert(pp1->pp_ref);
794	assert(pp1->pp_link == NULL);
795
796	// unmapping pp1 at PGSIZE should free it
797	page_remove(kern_pgdir, (void*) PGSIZE);
798	assert(check_va2pa(kern_pgdir, 0x0) == ~0);
799	assert(check_va2pa(kern_pgdir, PGSIZE) == ~0);
800	assert(pp1->pp_ref == 0);
801	assert(pp2->pp_ref == 0);
802
803	// so it should be returned by page_alloc
804	assert((pp = page_alloc(0)) && pp == pp1);
805
806	// should be no free memory
807	assert(!page_alloc(0));
808
809	// forcibly take pp0 back
810	assert(PTE_ADDR(kern_pgdir[0]) == page2pa(pp0));
811	kern_pgdir[0] = 0;
812	assert(pp0->pp_ref == 1);
813	pp0->pp_ref = 0;
814
815	// check pointer arithmetic in pgdir_walk
816	page_free(pp0);
817	va = (void*)(PGSIZE * NPDENTRIES + PGSIZE);
818	ptep = pgdir_walk(kern_pgdir, va, 1);
819	ptep1 = (pte_t *) KADDR(PTE_ADDR(kern_pgdir[PDX(va)]));
820	assert(ptep == ptep1 + PTX(va));
821	kern_pgdir[PDX(va)] = 0;
822	pp0->pp_ref = 0;
823
824	// check that new page tables get cleared
825	memset(page2kva(pp0), 0xFF, PGSIZE);
826	page_free(pp0);
827	pgdir_walk(kern_pgdir, 0x0, 1);
828	ptep = (pte_t *) page2kva(pp0);
829	for(i=0; i<NPTENTRIES; i++)
830		assert((ptep[i] & PTE_P) == 0);
831	kern_pgdir[0] = 0;
832	pp0->pp_ref = 0;
833
834	// give free list back
835	page_free_list = fl;
836
837	// free the pages we took
838	page_free(pp0);
839	page_free(pp1);
840	page_free(pp2);
841
842	cprintf("check_page() succeeded!\n");
843}
844
845// check page_insert, page_remove, &c, with an installed kern_pgdir
846static void
847check_page_installed_pgdir(void)
848{
849	struct PageInfo *pp, *pp0, *pp1, *pp2;
850	struct PageInfo *fl;
851	pte_t *ptep, *ptep1;
852	uintptr_t va;
853	int i;
854
855	// check that we can read and write installed pages
856	pp1 = pp2 = 0;
857	assert((pp0 = page_alloc(0)));
858	assert((pp1 = page_alloc(0)));
859	assert((pp2 = page_alloc(0)));
860	page_free(pp0);
861	memset(page2kva(pp1), 1, PGSIZE);
862	memset(page2kva(pp2), 2, PGSIZE);
863	page_insert(kern_pgdir, pp1, (void*) PGSIZE, PTE_W);
864	assert(pp1->pp_ref == 1);
865	assert(*(uint32_t *)PGSIZE == 0x01010101U);
866	page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W);
867	assert(*(uint32_t *)PGSIZE == 0x02020202U);
868	assert(pp2->pp_ref == 1);
869	assert(pp1->pp_ref == 0);
870	*(uint32_t *)PGSIZE = 0x03030303U;
871	assert(*(uint32_t *)page2kva(pp2) == 0x03030303U);
872	page_remove(kern_pgdir, (void*) PGSIZE);
873	assert(pp2->pp_ref == 0);
874
875	// forcibly take pp0 back
876	assert(PTE_ADDR(kern_pgdir[0]) == page2pa(pp0));
877	kern_pgdir[0] = 0;
878	assert(pp0->pp_ref == 1);
879	pp0->pp_ref = 0;
880
881	// free the pages we took
882	page_free(pp0);
883
884	cprintf("check_page_installed_pgdir() succeeded!\n");
885}