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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#include <kern/env.h>
12
13// These variables are set by i386_detect_memory()
14size_t npages;			// Amount of physical memory (in pages)
15static size_t npages_basemem;	// Amount of base memory (in pages)
16
17// These variables are set in mem_init()
18pde_t *kern_pgdir;		// Kernel's initial page directory
19struct PageInfo *pages;		// Physical page state array
20static struct PageInfo *page_free_list;	// Free list of physical pages
21
22
23// --------------------------------------------------------------
24// Detect machine's physical memory setup.
25// --------------------------------------------------------------
26
27static int
28nvram_read(int r)
29{
30	return mc146818_read(r) | (mc146818_read(r + 1) << 8);
31}
32
33static void
34i386_detect_memory(void)
35{
36	size_t npages_extmem;
37
38	// Use CMOS calls to measure available base & extended memory.
39	// (CMOS calls return results in kilobytes.)
40	npages_basemem = (nvram_read(NVRAM_BASELO) * 1024) / PGSIZE;
41	npages_extmem = (nvram_read(NVRAM_EXTLO) * 1024) / PGSIZE;
42
43	// Calculate the number of physical pages available in both base
44	// and extended memory.
45	if (npages_extmem)
46		npages = (EXTPHYSMEM / PGSIZE) + npages_extmem;
47	else
48		npages = npages_basemem;
49
50	cprintf("Physical memory: %uK available, base = %uK, extended = %uK\n",
51		npages * PGSIZE / 1024,
52		npages_basemem * PGSIZE / 1024,
53		npages_extmem * PGSIZE / 1024);
54}
55
56
57// --------------------------------------------------------------
58// Set up memory mappings above UTOP.
59// --------------------------------------------------------------
60
61static void boot_map_region(pde_t *pgdir, uintptr_t va, size_t size, physaddr_t pa, int perm);
62static void check_page_free_list(bool only_low_memory);
63static void check_page_alloc(void);
64static void check_kern_pgdir(void);
65static physaddr_t check_va2pa(pde_t *pgdir, uintptr_t va);
66static void check_page(void);
67static void check_page_installed_pgdir(void);
68
69// This simple physical memory allocator is used only while JOS is setting
70// up its virtual memory system.  page_alloc() is the real allocator.
71//
72// If n>0, allocates enough pages of contiguous physical memory to hold 'n'
73// bytes.  Doesn't initialize the memory.  Returns a kernel virtual address.
74//
75// If n==0, returns the address of the next free page without allocating
76// anything.
77//
78// If we're out of memory, boot_alloc should panic.
79// This function may ONLY be used during initialization,
80// before the page_free_list list has been set up.
81
82// Аллокатор, используемый при запуске системы виртуальной памяти JOS. 
83// Если параметр n>0, выделяет достаточное для хранения n байт количество страниц. 
84// Не инициализирует память. Если n=0, возвращает адрес следующей свободной страницы, ничего не выделяя. 
85// Если свободной памяти нет — вызывает kernel panic. 
86static void *
87boot_alloc(uint32_t n)
88{
89	static char *nextfree;	// virtual address of next byte of free memory
90	char *result;
91
92	// Initialize nextfree if this is the first time.
93	// 'end' is a magic symbol automatically generated by the linker,
94	// which points to the end of the kernel's bss segment:
95	// the first virtual address that the linker did *not* assign
96	// to any kernel code or global variables.
97	if (!nextfree) {
98		extern char end[];
99		nextfree = ROUNDUP((char *) end, PGSIZE);
100	}
101
102	// Allocate a chunk large enough to hold 'n' bytes, then update
103	// nextfree.  Make sure nextfree is kept aligned
104	// to a multiple of PGSIZE.
105	//
106	// LAB 6: Your code here.
107	result = nextfree;
108	if (n > 0){
109		nextfree += (uintptr_t)ROUNDUP((char*) n, PGSIZE); //Round up to the nearest multiple of PGSIZE
110		if ((uintptr_t)nextfree > (KERNBASE + npages * PGSIZE)){
111			panic("boot_alloc: error \n");
112		}
113	}
114	return result;
115}
116
117// Set up a two-level page table:
118//    kern_pgdir is its linear (virtual) address of the root
119//
120// This function only sets up the kernel part of the address space
121// (ie. addresses >= UTOP).  The user part of the address space
122// will be setup later.
123//
124// From UTOP to ULIM, the user is allowed to read but not write.
125// Above ULIM the user cannot read or write.
126void
127mem_init(void)
128{
129	// Find out how much memory the machine has (npages & npages_basemem).
130	i386_detect_memory();
131
132	// Remove this line when you're ready to test this function.
133	//panic("mem_init: This function is not finished\n");
134
135	//////////////////////////////////////////////////////////////////////
136	// create initial page directory.
137	kern_pgdir = (pde_t *) boot_alloc(PGSIZE);
138	memset(kern_pgdir, 0, PGSIZE);
139
140	//////////////////////////////////////////////////////////////////////
141	// Recursively insert PD in itself as a page table, to form
142	// a virtual page table at virtual address UVPT.
143	// (For now, you don't have understand the greater purpose of the
144	// following line.)
145
146	// Permissions: kernel R, user R
147	kern_pgdir[PDX(UVPT)] = PADDR(kern_pgdir) | PTE_U | PTE_P;
148
149	//////////////////////////////////////////////////////////////////////
150	// Allocate an array of npages 'struct PageInfo's and store it in 'pages'.
151	// The kernel uses this array to keep track of physical pages: for
152	// each physical page, there is a corresponding struct PageInfo in this
153	// array.  'npages' is the number of physical pages in memory.  Use memset
154	// to initialize all fields of each struct PageInfo to 0.
155	// Your code goes here:
156	pages = (struct PageInfo*)boot_alloc(npages * sizeof(struct PageInfo));
157	memset(pages, 0, npages * sizeof(struct PageInfo));
158
159	//////////////////////////////////////////////////////////////////////
160	// Make 'envs' point to an array of size 'NENV' of 'struct Env'.
161	// LAB 8: Your code here.
162	envs = (struct Env*)boot_alloc(NENV * sizeof(struct Env));
163
164	//////////////////////////////////////////////////////////////////////
165	// Now that we've allocated the initial kernel data structures, we set
166	// up the list of free physical pages. Once we've done so, all further
167	// memory management will go through the page_* functions. In
168	// particular, we can now map memory using boot_map_region
169	// or page_insert
170	page_init();
171
172	check_page_free_list(1);
173	check_page_alloc();
174	check_page();
175
176	//////////////////////////////////////////////////////////////////////
177	// Now we set up virtual memory
178
179	//////////////////////////////////////////////////////////////////////
180	// Map 'pages' read-only by the user at linear address UPAGES
181	// Permissions:
182	//    - the new image at UPAGES -- kernel R, user R
183	//      (ie. perm = PTE_U | PTE_P)
184	//    - pages itself -- kernel RW, user NONE
185	// Your code goes here:
186	boot_map_region(kern_pgdir, UPAGES, PTSIZE, PADDR(pages), PTE_U | PTE_P);
187	//////////////////////////////////////////////////////////////////////
188	// Map the 'envs' array read-only by the user at linear address UENVS
189	// (ie. perm = PTE_U | PTE_P).
190	// Permissions:
191	//    - the new image at UENVS  -- kernel R, user R
192	//    - envs itself -- kernel RW, user NONE
193	// LAB 8: Your code here.
194	boot_map_region(kern_pgdir, UENVS, PTSIZE, PADDR(envs), PTE_U | PTE_P);
195	//////////////////////////////////////////////////////////////////////
196	// Use the physical memory that 'bootstack' refers to as the kernel
197	// stack.  The kernel stack grows down from virtual address KSTACKTOP.
198	// We consider the entire range from [KSTACKTOP-PTSIZE, KSTACKTOP)
199	// to be the kernel stack, but break this into two pieces:
200	//     * [KSTACKTOP-KSTKSIZE, KSTACKTOP) -- backed by physical memory
201	//     * [KSTACKTOP-PTSIZE, KSTACKTOP-KSTKSIZE) -- not backed; so if
202	//       the kernel overflows its stack, it will fault rather than
203	//       overwrite memory.  Known as a "guard page".
204	//     Permissions: kernel RW, user NONE
205	// Your code goes here:
206	boot_map_region(kern_pgdir, KSTACKTOP - KSTKSIZE, KSTKSIZE, PADDR(bootstack), PTE_W);
207	//////////////////////////////////////////////////////////////////////
208	// Map all of physical memory at KERNBASE.
209	// Ie.  the VA range [KERNBASE, 2^32) should map to
210	//      the PA range [0, 2^32 - KERNBASE)
211	// We might not have 2^32 - KERNBASE bytes of physical memory, but
212	// we just set up the mapping anyway.
213	// Permissions: kernel RW, user NONE
214	// Your code goes here:
215	boot_map_region(kern_pgdir, KERNBASE, -KERNBASE, 0, PTE_W);
216	// Check that the initial page directory has been set up correctly.
217	check_kern_pgdir();
218
219	// Switch from the minimal entry page directory to the full kern_pgdir
220	// page table we just created.	Our instruction pointer should be
221	// somewhere between KERNBASE and KERNBASE+4MB right now, which is
222	// mapped the same way by both page tables.
223	//
224	// If the machine reboots at this point, you've probably set up your
225	// kern_pgdir wrong.
226	lcr3(PADDR(kern_pgdir));
227
228	check_page_free_list(0);
229
230	// entry.S set the really important flags in cr0 (including enabling
231	// paging).  Here we configure the rest of the flags that we care about.
232	{
233		uint32_t cr0 = rcr0();
234		cr0 |= CR0_PE|CR0_PG|CR0_AM|CR0_WP|CR0_NE|CR0_MP;
235		cr0 &= ~(CR0_TS|CR0_EM);
236		lcr0(cr0);
237	}
238
239	// Some more checks, only possible after kern_pgdir is installed.
240	check_page_installed_pgdir();
241}
242
243// --------------------------------------------------------------
244// Tracking of physical pages.
245// The 'pages' array has one 'struct PageInfo' entry per physical page.
246// Pages are reference counted, and free pages are kept on a linked list.
247// --------------------------------------------------------------
248
249//
250// Initialize page structure and memory free list.
251// After this is done, NEVER use boot_alloc again.  ONLY use the page
252// allocator functions below to allocate and deallocate physical
253// memory via the page_free_list.
254//
255void
256page_init(void)
257{
258	// The example code here marks all physical pages as free.
259	// However this is not truly the case.  What memory is free?
260	//  1) Mark physical page 0 as in use.
261	//     This way we preserve the real-mode IDT and BIOS structures
262	//     in case we ever need them.  (Currently we don't, but...)
263	//  2) The rest of base memory, [PGSIZE, npages_basemem * PGSIZE)
264	//     is free.
265	//  3) Then comes the IO hole [IOPHYSMEM, EXTPHYSMEM), which must
266	//     never be allocated.
267	//  4) Then extended memory [EXTPHYSMEM, ...).
268	//     Some of it is in use, some is free. Where is the kernel
269	//     in physical memory?  Which pages are already in use for
270	//     page tables and other data structures?
271	//
272	// Change the code to reflect this.
273	// NB: DO NOT actually touch the physical memory corresponding to
274	// free pages!
275	size_t i;
276
277	pages[0].pp_ref = 1; //счетчик ссылок на страницу
278
279	for (i = 1; i < npages_basemem; i++) {
280		pages[i].pp_ref = 0;
281		pages[i].pp_link = page_free_list;
282		page_free_list = &pages[i];
283	}
284
285	for (i = npages_basemem; i < EXTPHYSMEM/PGSIZE; i++){
286		//никогда не должно быть использовано -> пометим как занятое
287		pages[i].pp_ref = 1;
288	}
289
290	for (i = EXTPHYSMEM/PGSIZE; i < PGNUM(PADDR(boot_alloc(0))); i++){   
291		//boot_alloc(0) возвращает номер первой свободной страницы
292		//пометим как занятое 
293		pages[i].pp_ref = 1;
294	}  
295	for (i = PGNUM(PADDR(boot_alloc(0))); i < npages; i++){
296		//пометим как свободное
297		pages[i].pp_ref = 0;
298		pages[i].pp_link = page_free_list;
299		page_free_list = &pages[i];
300	}  
301	//PADDR - take kva and return va
302	//PGNUM - page number field of address
303}
304
305//
306// Allocates a physical page.  If (alloc_flags & ALLOC_ZERO), fills the entire
307// returned physical page with '\0' bytes.  Does NOT increment the reference
308// count of the page - the caller must do these if necessary (either explicitly
309// or via page_insert).
310//
311// Be sure to set the pp_link field of the allocated page to NULL so
312// page_free can check for double-free bugs.
313//
314// Returns NULL if out of free memory.
315//
316// Hint: use page2kva and memset
317struct PageInfo *
318page_alloc(int alloc_flags)
319{
320	 // Fill this function in
321	struct PageInfo *tmp_list = page_free_list;
322	//check to NULL -> free memory
323	if (tmp_list == NULL)
324		return NULL;
325	page_free_list = tmp_list->pp_link;
326	tmp_list->pp_link = NULL;
327	if (alloc_flags == ALLOC_ZERO){
328		//page to kernel virtual address
329		char* kva = page2kva(tmp_list);
330		//заполняем страницу нулями
331		memset(kva, 0, PGSIZE);
332	}
333	return tmp_list;
334}
335
336//
337// Return a page to the free list.
338// (This function should only be called when pp->pp_ref reaches 0.)
339//
340void
341page_free(struct PageInfo *pp)
342{
343	// Fill this function in
344	// Hint: You may want to panic if pp->pp_ref is nonzero or
345	// pp->pp_link is not NULL.
346	if (pp->pp_ref != 0 || pp->pp_link != NULL){
347		panic("page_free:error\n");
348	}
349	pp->pp_link = page_free_list;
350	page_free_list = pp;
351}
352
353//
354// Decrement the reference count on a page,
355// freeing it if there are no more refs.
356//
357void
358page_decref(struct PageInfo* pp)
359{
360	if (--pp->pp_ref == 0)
361		page_free(pp);
362}
363
364// Given 'pgdir', a pointer to a page directory, pgdir_walk returns
365// a pointer to the page table entry (PTE) for linear address 'va'.
366// This requires walking the two-level page table structure.
367//
368// The relevant page table page might not exist yet.
369// If this is true, and create == false, then pgdir_walk returns NULL.
370// Otherwise, pgdir_walk allocates a new page table page with page_alloc.
371//    - If the allocation fails, pgdir_walk returns NULL.
372//    - Otherwise, the new page's reference count is incremented,
373//	the page is cleared,
374//	and pgdir_walk returns a pointer into the new page table page.
375//
376// Hint 1: you can turn a Page * into the physical address of the
377// page it refers to with page2pa() from kern/pmap.h.
378//
379// Hint 2: the x86 MMU checks permission bits in both the page directory
380// and the page table, so it's safe to leave permissions in the page
381// directory more permissive than strictly necessary.
382//
383// Hint 3: look at inc/mmu.h for useful macros that mainipulate page
384// table and page directory entries.
385//
386pte_t *
387pgdir_walk(pde_t *pgdir, const void *va, int create)
388{
389	// Fill this function in
390	struct PageInfo *page;
391	pde_t pde_pointer;
392	pte_t *pte_pointer;
393	//PDX(va) give a page directory index
394	size_t pdx = PDX(va);
395	//PTX(va) give a page table index
396	size_t ptx = PTX(va);
397	//pgdir - a pointer to a page directory
398	pde_pointer = pgdir[pdx];
399	//check to present of page
400	if (PTE_P & pde_pointer){
401		//PTE_ADDR : Address in page table or page directory entry
402		//kern can't working with pa
403		// KADDR :  pa -> kva
404		pte_pointer = KADDR(PTE_ADDR(pde_pointer));
405	} else {
406		if (create == false){
407			return NULL;
408		}
409		page = page_alloc(ALLOC_ZERO);
410		if (!page){
411			return NULL;
412		}
413		pgdir[pdx] = page2pa(page) | PTE_P | PTE_W | PTE_U;
414		pte_pointer = (pte_t*)page2kva(page);
415		page->pp_ref++;
416	}
417	return &pte_pointer[ptx];
418}
419
420//
421// Map [va, va+size) of virtual address space to physical [pa, pa+size)
422// in the page table rooted at pgdir.  Size is a multiple of PGSIZE, and
423// va and pa are both page-aligned.
424// Use permission bits perm|PTE_P for the entries.
425//
426// This function is only intended to set up the ``static'' mappings
427// above UTOP. As such, it should *not* change the pp_ref field on the
428// mapped pages.
429//
430// Hint: the TA solution uses pgdir_walk
431static void
432boot_map_region(pde_t *pgdir, uintptr_t va, size_t size, physaddr_t pa, int perm)
433{
434	// Fill this function in
435	int page_count = size / PGSIZE;
436	while(page_count > 0){
437		//получение записи в таблице страниц
438		pte_t* pte_pointer = pgdir_walk(pgdir, (void *)va, 1);
439		//ставим в соответсвие физический адрес с соотвующими флагами
440		*pte_pointer = pa | perm | PTE_P;
441		pa += PGSIZE;
442		va += PGSIZE;
443		page_count --;
444	}
445}
446
447//
448// Map the physical page 'pp' at virtual address 'va'.
449// The permissions (the low 12 bits) of the page table entry
450// should be set to 'perm|PTE_P'.
451//
452// Requirements
453//   - If there is already a page mapped at 'va', it should be page_remove()d.
454//   - If necessary, on demand, a page table should be allocated and inserted
455//     into 'pgdir'.
456//   - pp->pp_ref should be incremented if the insertion succeeds.
457//   - The TLB must be invalidated if a page was formerly present at 'va'.
458//
459// Corner-case hint: Make sure to consider what happens when the same
460// pp is re-inserted at the same virtual address in the same pgdir.
461// However, try not to distinguish this case in your code, as this
462// frequently leads to subtle bugs; there's an elegant way to handle
463// everything in one code path.
464//
465// RETURNS:
466//   0 on success
467//   -E_NO_MEM, if page table couldn't be allocated
468//
469// Hint: The TA solution is implemented using pgdir_walk, page_remove,
470// and page2pa.
471//
472int
473page_insert(pde_t *pgdir, struct PageInfo *pp, void *va, int perm)
474{
475	// Fill this function in
476	bool flag = 1;
477	//получаем запись в таблице по va 
478	pte_t * pte_pointer = pgdir_walk(pgdir, va, 1);
479	if(!pte_pointer){
480		//page table couldn't be allocated
481		return -E_NO_MEM;
482	}
483	//получаем физический адрес странички
484	physaddr_t pa = page2pa(pp);
485	if (*pte_pointer & PTE_P){
486		//если страница уже отображена
487		if (pa == PTE_ADDR(*pte_pointer)){
488			flag = 0;
489		}
490		if (flag){
491			page_remove(pgdir, va);
492		}
493	}
494	if (flag){
495		pp->pp_ref++;
496		tlb_invalidate(pgdir, va);
497	}
498	*pte_pointer = pa | perm | PTE_P;
499	return 0;
500}
501
502//
503// Return the page mapped at virtual address 'va'.
504// If pte_store is not zero, then we store in it the address
505// of the pte for this page.  This is used by page_remove and
506// can be used to verify page permissions for syscall arguments,
507// but should not be used by most callers.
508//
509// Return NULL if there is no page mapped at va.
510//
511// Hint: the TA solution uses pgdir_walk and pa2page.
512//
513struct PageInfo *
514page_lookup(pde_t *pgdir, void *va, pte_t **pte_store)
515{
516	// Fill this function in
517	//получаем запись в таблице страниц
518	pte_t* pte_pointer = pgdir_walk(pgdir, va, 0);
519	if (!pte_pointer || !(PTE_P & *pte_pointer)){
520		return NULL;
521	}
522	//см указания сверху 
523	if (pte_store){
524		*pte_store = pte_pointer;
525	}
526	//take a pa
527	physaddr_t pa = PTE_ADDR(*pte_pointer);
528	//return a page
529	return pa2page(pa);
530}
531
532//
533// Unmaps the physical page at virtual address 'va'.
534// If there is no physical page at that address, silently does nothing.
535//
536// Details:
537//   - The ref count on the physical page should decrement.
538//   - The physical page should be freed if the refcount reaches 0.
539//   - The pg table entry corresponding to 'va' should be set to 0.
540//     (if such a PTE exists)
541//   - The TLB must be invalidated if you remove an entry from
542//     the page table.
543//
544// Hint: The TA solution is implemented using page_lookup,
545// 	tlb_invalidate, and page_decref.
546//
547void
548page_remove(pde_t *pgdir, void *va)
549{
550	// Fill this function in
551	pte_t *pte_pointer;
552	//ищем страничку
553	struct PageInfo *page = page_lookup(pgdir, va, &pte_pointer);
554	if (!(PTE_P & *pte_pointer) || !pte_pointer)
555		//is no physical page at that address
556		return;
557	//The ref count on the physical page should decrement.
558	//The physical page should be freed if the refcount reaches 0.
559	page_decref(page);
560	//The pg table entry corresponding to 'va' should be set to 0.
561	*pte_pointer = 0;
562	//The TLB must be invalidated if you remove an entry from
563	//the page table.
564	tlb_invalidate(pgdir, va);
565}
566
567//
568// Invalidate a TLB entry, but only if the page tables being
569// edited are the ones currently in use by the processor.
570//
571void
572tlb_invalidate(pde_t *pgdir, void *va)
573{
574	// Flush the entry only if we're modifying the current address space.
575	if (!curenv || curenv->env_pgdir == pgdir)
576		invlpg(va);
577}
578
579//
580// Reserve size bytes in the MMIO region and map [pa,pa+size) at this
581// location.  Return the base of the reserved region.  size does *not*
582// have to be multiple of PGSIZE.
583//
584void *
585mmio_map_region(physaddr_t pa, size_t size)
586{
587	// Where to start the next region.  Initially, this is the
588	// beginning of the MMIO region.  Because this is static, its
589	// value will be preserved between calls to mmio_map_region
590	// (just like nextfree in boot_alloc).
591	static uintptr_t base = MMIOBASE; base=base;
592
593	// Reserve size bytes of virtual memory starting at base and
594	// map physical pages [pa,pa+size) to virtual addresses
595	// [base,base+size).  Since this is device memory and not
596	// regular DRAM, you'll have to tell the CPU that it isn't
597	// safe to cache access to this memory.  Luckily, the page
598	// tables provide bits for this purpose; simply create the
599	// mapping with PTE_PCD|PTE_PWT (cache-disable and
600	// write-through) in addition to PTE_W.  (If you're interested
601	// in more details on this, see section 10.5 of IA32 volume
602	// 3A.)
603	//
604	// Be sure to round size up to a multiple of PGSIZE and to
605	// handle if this reservation would overflow MMIOLIM (it's
606	// okay to simply panic if this happens).
607	//
608	// Hint: The staff solution uses boot_map_region.
609	//
610	// Your code here:
611	panic("mmio_map_region not implemented");
612}
613
614static uintptr_t user_mem_check_addr;
615
616//
617// Check that an environment is allowed to access the range of memory
618// [va, va+len) with permissions 'perm | PTE_P'.
619// Normally 'perm' will contain PTE_U at least, but this is not required.
620// 'va' and 'len' need not be page-aligned; you must test every page that
621// contains any of that range.  You will test either 'len/PGSIZE',
622// 'len/PGSIZE + 1', or 'len/PGSIZE + 2' pages.
623//
624// A user program can access a virtual address if (1) the address is below
625// ULIM, and (2) the page table gives it permission.  These are exactly
626// the tests you should implement here.
627//
628// If there is an error, set the 'user_mem_check_addr' variable to the first
629// erroneous virtual address.
630//
631// Returns 0 if the user program can access this range of addresses,
632// and -E_FAULT otherwise.
633//
634int
635user_mem_check(struct Env *env, const void *va, size_t len, int perm)
636{
637	// LAB 8: Your code here.
638	bool failure = 0;
639	perm = perm | PTE_P;
640	uintptr_t addr = ROUNDDOWN((uintptr_t)va, PGSIZE);
641	uintptr_t end = ROUNDUP((uintptr_t)va + len, PGSIZE);
642	while (addr < end) {
643		if (addr >= ULIM) {
644            failure = 1;
645			break;
646		}	
647	    pte_t *pte = pgdir_walk(env->env_pgdir, (void *)addr, 0);
648	    if (!pte) {
649	        failure = 1;
650			break;
651		}	
652        if ((*pte & perm) != perm) {
653		    failure = 1;
654			break;
655		}
656		addr += PGSIZE;
657	}
658	if (!failure)
659		return 0;
660	user_mem_check_addr = (uintptr_t)va;
661	if (user_mem_check_addr < addr)
662		user_mem_check_addr = addr;
663	return -E_FAULT;
664}
665
666//
667// Checks that environment 'env' is allowed to access the range
668// of memory [va, va+len) with permissions 'perm | PTE_U | PTE_P'.
669// If it can, then the function simply returns.
670// If it cannot, 'env' is destroyed and, if env is the current
671// environment, this function will not return.
672//
673void
674user_mem_assert(struct Env *env, const void *va, size_t len, int perm)
675{
676	if (user_mem_check(env, va, len, perm | PTE_U) < 0) {
677		cprintf("[%08x] user_mem_check assertion failure for "
678			"va %08x\n", env->env_id, user_mem_check_addr);
679		env_destroy(env);	// may not return
680	}
681}
682
683
684// --------------------------------------------------------------
685// Checking functions.
686// --------------------------------------------------------------
687
688//
689// Check that the pages on the page_free_list are reasonable.
690//
691static void
692check_page_free_list(bool only_low_memory)
693{
694	struct PageInfo *pp;
695	unsigned pdx_limit = only_low_memory ? 1 : NPDENTRIES;
696	int nfree_basemem = 0, nfree_extmem = 0;
697	char *first_free_page;
698
699	if (!page_free_list)
700		panic("'page_free_list' is a null pointer!");
701
702	if (only_low_memory) {
703		// Move pages with lower addresses first in the free
704		// list, since entry_pgdir does not map all pages.
705		struct PageInfo *pp1, *pp2;
706		struct PageInfo **tp[2] = { &pp1, &pp2 };
707		for (pp = page_free_list; pp; pp = pp->pp_link) {
708			int pagetype = PDX(page2pa(pp)) >= pdx_limit;
709			*tp[pagetype] = pp;
710			tp[pagetype] = &pp->pp_link;
711		}
712		*tp[1] = 0;
713		*tp[0] = pp2;
714		page_free_list = pp1;
715	}
716
717	// if there's a page that shouldn't be on the free list,
718	// try to make sure it eventually causes trouble.
719	for (pp = page_free_list; pp; pp = pp->pp_link)
720		if (PDX(page2pa(pp)) < pdx_limit)
721			memset(page2kva(pp), 0x97, 128);
722
723	first_free_page = (char *) boot_alloc(0);
724	for (pp = page_free_list; pp; pp = pp->pp_link) {
725		// check that we didn't corrupt the free list itself
726		assert(pp >= pages);
727		assert(pp < pages + npages);
728		assert(((char *) pp - (char *) pages) % sizeof(*pp) == 0);
729
730		// check a few pages that shouldn't be on the free list
731		assert(page2pa(pp) != 0);
732		assert(page2pa(pp) != IOPHYSMEM);
733		assert(page2pa(pp) != EXTPHYSMEM - PGSIZE);
734		assert(page2pa(pp) != EXTPHYSMEM);
735		assert(page2pa(pp) < EXTPHYSMEM || (char *) page2kva(pp) >= first_free_page);
736
737		if (page2pa(pp) < EXTPHYSMEM)
738			++nfree_basemem;
739		else
740			++nfree_extmem;
741	}
742
743	assert(nfree_basemem > 0);
744	assert(nfree_extmem > 0);
745}
746
747//
748// Check the physical page allocator (page_alloc(), page_free(),
749// and page_init()).
750//
751static void
752check_page_alloc(void)
753{
754	struct PageInfo *pp, *pp0, *pp1, *pp2;
755	int nfree;
756	struct PageInfo *fl;
757	char *c;
758	int i;
759
760	if (!pages)
761		panic("'pages' is a null pointer!");
762
763	// check number of free pages
764	for (pp = page_free_list, nfree = 0; pp; pp = pp->pp_link)
765		++nfree;
766
767	// should be able to allocate three pages
768	pp0 = pp1 = pp2 = 0;
769	assert((pp0 = page_alloc(0)));
770	assert((pp1 = page_alloc(0)));
771	assert((pp2 = page_alloc(0)));
772
773	assert(pp0);
774	assert(pp1 && pp1 != pp0);
775	assert(pp2 && pp2 != pp1 && pp2 != pp0);
776	assert(page2pa(pp0) < npages*PGSIZE);
777	assert(page2pa(pp1) < npages*PGSIZE);
778	assert(page2pa(pp2) < npages*PGSIZE);
779
780	// temporarily steal the rest of the free pages
781	fl = page_free_list;
782	page_free_list = 0;
783
784	// should be no free memory
785	assert(!page_alloc(0));
786
787	// free and re-allocate?
788	page_free(pp0);
789	page_free(pp1);
790	page_free(pp2);
791	pp0 = pp1 = pp2 = 0;
792	assert((pp0 = page_alloc(0)));
793	assert((pp1 = page_alloc(0)));
794	assert((pp2 = page_alloc(0)));
795	assert(pp0);
796	assert(pp1 && pp1 != pp0);
797	assert(pp2 && pp2 != pp1 && pp2 != pp0);
798	assert(!page_alloc(0));
799
800	// test flags
801	memset(page2kva(pp0), 1, PGSIZE);
802	page_free(pp0);
803	assert((pp = page_alloc(ALLOC_ZERO)));
804	assert(pp && pp0 == pp);
805	c = page2kva(pp);
806	for (i = 0; i < PGSIZE; i++)
807		assert(c[i] == 0);
808
809	// give free list back
810	page_free_list = fl;
811
812	// free the pages we took
813	page_free(pp0);
814	page_free(pp1);
815	page_free(pp2);
816
817	// number of free pages should be the same
818	for (pp = page_free_list; pp; pp = pp->pp_link)
819		--nfree;
820	assert(nfree == 0);
821
822	cprintf("check_page_alloc() succeeded!\n");
823
824	// for(;pp0 != NULL;) {
825	// 	pp2 = pp1;
826	// 	pp1 = pp0;
827	// 	pp0 = page_alloc(0);
828	// }
829	// page_free(pp1);
830	// page_free(pp2);
831	// pp1 = page_alloc(0);
832}
833
834struct PageInfo* last_page(void){
835	struct PageInfo *last_page = page_free_list;
836	if (page_free_list == NULL)
837		return NULL;
838	while(last_page->pp_link != NULL){
839		last_page = last_page->pp_link;
840	}
841	return last_page;
842}
843
844//
845// Checks that the kernel part of virtual address space
846// has been setup roughly correctly (by mem_init()).
847//
848// This function doesn't test every corner case,
849// but it is a pretty good sanity check.
850//
851
852static void
853check_kern_pgdir(void)
854{
855	uint32_t i, n;
856	pde_t *pgdir;
857
858	pgdir = kern_pgdir;
859
860	// check pages array
861	n = ROUNDUP(npages*sizeof(struct PageInfo), PGSIZE);
862	for (i = 0; i < n; i += PGSIZE)
863		assert(check_va2pa(pgdir, UPAGES + i) == PADDR(pages) + i);
864
865	// check envs array (new test for lab 8)
866	n = ROUNDUP(NENV*sizeof(struct Env), PGSIZE);
867	for (i = 0; i < n; i += PGSIZE)
868		assert(check_va2pa(pgdir, UENVS + i) == PADDR(envs) + i);
869
870	// check phys mem
871	for (i = 0; i < npages * PGSIZE; i += PGSIZE)
872		assert(check_va2pa(pgdir, KERNBASE + i) == i);
873
874	// check kernel stack
875	for (i = 0; i < KSTKSIZE; i += PGSIZE)
876		assert(check_va2pa(pgdir, KSTACKTOP - KSTKSIZE + i) == PADDR(bootstack) + i);
877	assert(check_va2pa(pgdir, KSTACKTOP - PTSIZE) == ~0);
878
879	// check PDE permissions
880	for (i = 0; i < NPDENTRIES; i++) {
881		switch (i) {
882		case PDX(UVPT):
883		case PDX(KSTACKTOP-1):
884		case PDX(UPAGES):
885		case PDX(UENVS):
886			assert(pgdir[i] & PTE_P);
887			break;
888		default:
889			if (i >= PDX(KERNBASE)) {
890				assert(pgdir[i] & PTE_P);
891				assert(pgdir[i] & PTE_W);
892			} else
893				assert(pgdir[i] == 0);
894			break;
895		}
896	}
897	cprintf("check_kern_pgdir() succeeded!\n");
898}
899
900// This function returns the physical address of the page containing 'va',
901// defined by the page directory 'pgdir'.  The hardware normally performs
902// this functionality for us!  We define our own version to help check
903// the check_kern_pgdir() function; it shouldn't be used elsewhere.
904
905static physaddr_t
906check_va2pa(pde_t *pgdir, uintptr_t va)
907{
908	pte_t *p;
909
910	pgdir = &pgdir[PDX(va)];
911	if (!(*pgdir & PTE_P))
912		return ~0;
913	p = (pte_t*) KADDR(PTE_ADDR(*pgdir));
914	if (!(p[PTX(va)] & PTE_P))
915		return ~0;
916	return PTE_ADDR(p[PTX(va)]);
917}
918
919
920// check page_insert, page_remove, &c
921static void
922check_page(void)
923{
924	struct PageInfo *pp, *pp0, *pp1, *pp2;
925	struct PageInfo *fl;
926	pte_t *ptep, *ptep1;
927	void *va;
928	int i;
929
930	// should be able to allocate three pages
931	pp0 = pp1 = pp2 = 0;
932	assert((pp0 = page_alloc(0)));
933	assert((pp1 = page_alloc(0)));
934	assert((pp2 = page_alloc(0)));
935
936	assert(pp0);
937	assert(pp1 && pp1 != pp0);
938	assert(pp2 && pp2 != pp1 && pp2 != pp0);
939
940	// temporarily steal the rest of the free pages
941	fl = page_free_list;
942	page_free_list = 0;
943
944	// should be no free memory
945	assert(!page_alloc(0));
946
947	// there is no page allocated at address 0
948	assert(page_lookup(kern_pgdir, (void *) 0x0, &ptep) == NULL);
949
950	// there is no free memory, so we can't allocate a page table
951	assert(page_insert(kern_pgdir, pp1, 0x0, PTE_W) < 0);
952
953	// free pp0 and try again: pp0 should be used for page table
954	page_free(pp0);
955	assert(page_insert(kern_pgdir, pp1, 0x0, PTE_W) == 0);
956	assert(PTE_ADDR(kern_pgdir[0]) == page2pa(pp0));
957	assert(check_va2pa(kern_pgdir, 0x0) == page2pa(pp1));
958	assert(pp1->pp_ref == 1);
959	assert(pp0->pp_ref == 1);
960
961	// should be able to map pp2 at PGSIZE because pp0 is already allocated for page table
962	assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W) == 0);
963	assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp2));
964	assert(pp2->pp_ref == 1);
965
966	// should be no free memory
967	assert(!page_alloc(0));
968
969	// should be able to map pp2 at PGSIZE because it's already there
970	assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W) == 0);
971	assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp2));
972	assert(pp2->pp_ref == 1);
973
974	// pp2 should NOT be on the free list
975	// could happen in ref counts are handled sloppily in page_insert
976	assert(!page_alloc(0));
977
978	// check that pgdir_walk returns a pointer to the pte
979	ptep = (pte_t *) KADDR(PTE_ADDR(kern_pgdir[PDX(PGSIZE)]));
980	assert(pgdir_walk(kern_pgdir, (void*)PGSIZE, 0) == ptep+PTX(PGSIZE));
981
982	// should be able to change permissions too.
983	assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W|PTE_U) == 0);
984	assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp2));
985	assert(pp2->pp_ref == 1);
986	assert(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_U);
987	assert(kern_pgdir[0] & PTE_U);
988
989	// should be able to remap with fewer permissions
990	assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W) == 0);
991	assert(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_W);
992	assert(!(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_U));
993
994	// should not be able to map at PTSIZE because need free page for page table
995	assert(page_insert(kern_pgdir, pp0, (void*) PTSIZE, PTE_W) < 0);
996
997	// insert pp1 at PGSIZE (replacing pp2)
998	assert(page_insert(kern_pgdir, pp1, (void*) PGSIZE, PTE_W) == 0);
999	assert(!(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_U));
1000
1001	// should have pp1 at both 0 and PGSIZE, pp2 nowhere, ...
1002	assert(check_va2pa(kern_pgdir, 0) == page2pa(pp1));
1003	assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp1));
1004	// ... and ref counts should reflect this
1005	assert(pp1->pp_ref == 2);
1006	assert(pp2->pp_ref == 0);
1007
1008	// pp2 should be returned by page_alloc
1009	assert((pp = page_alloc(0)) && pp == pp2);
1010
1011	// unmapping pp1 at 0 should keep pp1 at PGSIZE
1012	page_remove(kern_pgdir, 0x0);
1013	assert(check_va2pa(kern_pgdir, 0x0) == ~0);
1014	assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp1));
1015	assert(pp1->pp_ref == 1);
1016	assert(pp2->pp_ref == 0);
1017
1018	// test re-inserting pp1 at PGSIZE
1019	assert(page_insert(kern_pgdir, pp1, (void*) PGSIZE, 0) == 0);
1020	assert(pp1->pp_ref);
1021	assert(pp1->pp_link == NULL);
1022
1023	// unmapping pp1 at PGSIZE should free it
1024	page_remove(kern_pgdir, (void*) PGSIZE);
1025	assert(check_va2pa(kern_pgdir, 0x0) == ~0);
1026	assert(check_va2pa(kern_pgdir, PGSIZE) == ~0);
1027	assert(pp1->pp_ref == 0);
1028	assert(pp2->pp_ref == 0);
1029
1030	// so it should be returned by page_alloc
1031	assert((pp = page_alloc(0)) && pp == pp1);
1032
1033	// should be no free memory
1034	assert(!page_alloc(0));
1035
1036	// forcibly take pp0 back
1037	assert(PTE_ADDR(kern_pgdir[0]) == page2pa(pp0));
1038	kern_pgdir[0] = 0;
1039	assert(pp0->pp_ref == 1);
1040	pp0->pp_ref = 0;
1041
1042	// check pointer arithmetic in pgdir_walk
1043	page_free(pp0);
1044	va = (void*)(PGSIZE * NPDENTRIES + PGSIZE);
1045	ptep = pgdir_walk(kern_pgdir, va, 1);
1046	ptep1 = (pte_t *) KADDR(PTE_ADDR(kern_pgdir[PDX(va)]));
1047	assert(ptep == ptep1 + PTX(va));
1048	kern_pgdir[PDX(va)] = 0;
1049	pp0->pp_ref = 0;
1050
1051	// check that new page tables get cleared
1052	memset(page2kva(pp0), 0xFF, PGSIZE);
1053	page_free(pp0);
1054	pgdir_walk(kern_pgdir, 0x0, 1);
1055	ptep = (pte_t *) page2kva(pp0);
1056	for(i=0; i<NPTENTRIES; i++)
1057		assert((ptep[i] & PTE_P) == 0);
1058	kern_pgdir[0] = 0;
1059	pp0->pp_ref = 0;
1060
1061	// give free list back
1062	page_free_list = fl;
1063
1064	// free the pages we took
1065	page_free(pp0);
1066	page_free(pp1);
1067	page_free(pp2);
1068
1069	cprintf("check_page() succeeded!\n");
1070}
1071
1072// check page_insert, page_remove, &c, with an installed kern_pgdir
1073static void
1074check_page_installed_pgdir(void)
1075{
1076	struct PageInfo *pp0, *pp1, *pp2;
1077
1078	// check that we can read and write installed pages
1079	pp1 = pp2 = 0;
1080	assert((pp0 = page_alloc(0)));
1081	assert((pp1 = page_alloc(0)));
1082	assert((pp2 = page_alloc(0)));
1083	page_free(pp0);
1084	memset(page2kva(pp1), 1, PGSIZE);
1085	memset(page2kva(pp2), 2, PGSIZE);
1086	page_insert(kern_pgdir, pp1, (void*) PGSIZE, PTE_W);
1087	assert(pp1->pp_ref == 1);
1088	assert(*(uint32_t *)PGSIZE == 0x01010101U);
1089	page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W);
1090	assert(*(uint32_t *)PGSIZE == 0x02020202U);
1091	assert(pp2->pp_ref == 1);
1092	assert(pp1->pp_ref == 0);
1093	*(uint32_t *)PGSIZE = 0x03030303U;
1094	assert(*(uint32_t *)page2kva(pp2) == 0x03030303U);
1095	page_remove(kern_pgdir, (void*) PGSIZE);
1096	assert(pp2->pp_ref == 0);
1097
1098	// forcibly take pp0 back
1099	assert(PTE_ADDR(kern_pgdir[0]) == page2pa(pp0));
1100	kern_pgdir[0] = 0;
1101	assert(pp0->pp_ref == 1);
1102	pp0->pp_ref = 0;
1103
1104	// free the pages we took
1105	page_free(pp0);
1106
1107	cprintf("check_page_installed_pgdir() succeeded!\n");
1108}