866L7Ged

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#include <kern/cpu.h>
13
14// These variables are set by i386_detect_memory()
15size_t npages;			// Amount of physical memory (in pages)
16static size_t npages_basemem;	// Amount of base memory (in pages)
17
18// These variables are set in mem_init()
19pde_t *kern_pgdir;		// Kernel's initial page directory
20struct PageInfo *pages;		// Physical page state array
21static struct PageInfo *page_free_list;	// Free list of physical pages
22
23
24// --------------------------------------------------------------
25// Detect machine's physical memory setup.
26// --------------------------------------------------------------
27
28static int
29nvram_read(int r)
30{
31	return mc146818_read(r) | (mc146818_read(r + 1) << 8);
32}
33
34static void
35i386_detect_memory(void)
36{
37	size_t basemem, extmem, ext16mem, totalmem;
38
39	// Use CMOS calls to measure available base & extended memory.
40	// (CMOS calls return results in kilobytes.)
41	basemem = nvram_read(NVRAM_BASELO);
42	extmem = nvram_read(NVRAM_EXTLO);
43	ext16mem = nvram_read(NVRAM_EXT16LO) * 64;
44
45	// Calculate the number of physical pages available in both base
46	// and extended memory.
47	if (ext16mem)
48		totalmem = 16 * 1024 + ext16mem;
49	else if (extmem)
50		totalmem = 1 * 1024 + extmem;
51	else
52		totalmem = basemem;
53
54	npages = totalmem / (PGSIZE / 1024);
55	npages_basemem = basemem / (PGSIZE / 1024);
56
57	cprintf("Physical memory: %uK available, base = %uK, extended = %uK\n",
58		totalmem, basemem, totalmem - basemem);
59}
60
61
62// --------------------------------------------------------------
63// Set up memory mappings above UTOP.
64// --------------------------------------------------------------
65
66static void mem_init_mp(void);
67static void boot_map_region(pde_t *pgdir, uintptr_t va, size_t size, physaddr_t pa, int perm);
68static void check_page_free_list(bool only_low_memory);
69static void check_page_alloc(void);
70static void check_kern_pgdir(void);
71static physaddr_t check_va2pa(pde_t *pgdir, uintptr_t va);
72static void check_page(void);
73static void check_page_installed_pgdir(void);
74
75// This simple physical memory allocator is used only while JOS is setting
76// up its virtual memory system.  page_alloc() is the real allocator.
77//
78// If n>0, allocates enough pages of contiguous physical memory to hold 'n'
79// bytes.  Doesn't initialize the memory.  Returns a kernel virtual address.
80//
81// If n==0, returns the address of the next free page without allocating
82// anything.
83//
84// If we're out of memory, boot_alloc should panic.
85// This function may ONLY be used during initialization,
86// before the page_free_list list has been set up.
87static void *
88boot_alloc(uint32_t n)
89{
90	static char *nextfree;	// virtual address of next byte of free memory
91	//char *result;
92
93	// Initialize nextfree if this is the first time.
94	// 'end' is a magic symbol automatically generated by the linker,
95	// which points to the end of the kernel's bss segment:
96	// the first virtual address that the linker did *not* assign
97	// to any kernel code or global variables.
98	
99	if (!nextfree) {  //nextfree je 0
100		extern char end[];
101		nextfree = ROUNDUP((char *) end, PGSIZE);
102	}
103
104	// Allocate a chunk large enough to hold 'n' bytes, then update
105	// nextfree.  Make sure nextfree is kept aligned
106	// to a multiple of PGSIZE.
107	//
108	// LAB 2: Your code here.
109
110	// ROUNDUP to make sure nextfree is kept aligned
111	// to a multiple of PGSIZE
112
113	if(n==0) return nextfree;
114 
115 	if (n > 0 || n < 0) {
116		nextfree = ROUNDUP((char *) (nextfree+n), PGSIZE);
117		char **adresa = &nextfree; 
118
119		int freebytes = 0;
120		uint32_t RAMsize = npages*PGSIZE;
121		
122		//}
123	}
124 
125        return nextfree;
126}
127
128// Set up a two-level page table:
129//    kern_pgdir is its linear (virtual) address of the root
130//
131// This function only sets up the kernel part of the address space
132// (ie. addresses >= UTOP).  The user part of the address space
133// will be setup later.
134//
135// From UTOP to ULIM, the user is allowed to read but not write.
136// Above ULIM the user cannot read or write.
137void
138mem_init(void)
139{
140	uint32_t cr0;
141	size_t n;
142
143	// Find out how much memory the machine has (npages & npages_basemem).
144	i386_detect_memory();
145
146	// Remove this line when you're ready to test this function.
147	//panic("mem_init: This function is not finished\n");
148
149	//////////////////////////////////////////////////////////////////////
150	// create initial page directory.
151	kern_pgdir = (pde_t *) boot_alloc(PGSIZE);
152	memset(kern_pgdir, 0, PGSIZE);
153
154	//////////////////////////////////////////////////////////////////////
155	// Recursively insert PD in itself as a page table, to form
156	// a virtual page table at virtual address UVPT.
157	// (For now, you don't have understand the greater purpose of the
158	// following line.)
159
160	// Permissions: kernel R, user R
161	kern_pgdir[PDX(UVPT)] = PADDR(kern_pgdir) | PTE_U | PTE_P;
162
163	//////////////////////////////////////////////////////////////////////
164	// Allocate an array of npages 'struct PageInfo's and store it in 'pages'.
165	// The kernel uses this array to keep track of physical pages: for
166	// each physical page, there is a corresponding struct PageInfo in this
167	// array.  'npages' is the number of physical pages in memory.  Use memset
168	// to initialize all fields of each struct PageInfo to 0.
169	// Your code goes here:
170
171	pages = (struct PageInfo *)boot_alloc(npages * sizeof(struct PageInfo));
172
173	size_t iterator;	
174	
175	for(iterator=0;iterator<npages;iterator++) {
176		memset(&pages[iterator].pp_link,0,sizeof(uint16_t));
177		memset(&pages[iterator].pp_ref,0,sizeof(uint16_t));
178	}
179
180	//////////////////////////////////////////////////////////////////////
181	// Make 'envs' point to an array of size 'NENV' of 'struct Env'.
182	// LAB 3: Your code here.
183	
184	envs = (struct Env *)boot_alloc(NENV * sizeof(struct Env));
185
186
187	//////////////////////////////////////////////////////////////////////
188	// Now that we've allocated the initial kernel data structures, we set
189	// up the list of free physical pages. Once we've done so, all further
190	// memory management will go through the page_* functions. In
191	// particular, we can now map memory using boot_map_region
192	// or page_insert
193	page_init();
194
195	check_page_free_list(1);
196	check_page_alloc();
197	check_page();
198
199	//////////////////////////////////////////////////////////////////////
200	// Now we set up virtual memory
201
202	//////////////////////////////////////////////////////////////////////
203	// Map 'pages' read-only by the user at linear address UPAGES
204	// Permissions:
205	//    - the new image at UPAGES -- kernel R, user R
206	//      (ie. perm = PTE_U | PTE_P)
207	//    - pages itself -- kernel RW, user NONE
208	// Your code goes here:
209	
210	boot_map_region(kern_pgdir, UPAGES, PTSIZE, PADDR(pages), PTE_U | PTE_P);
211
212
213
214
215	//////////////////////////////////////////////////////////////////////
216	// Map the 'envs' array read-only by the user at linear address UENVS
217	// (ie. perm = PTE_U | PTE_P).
218	// Permissions:
219	//    - the new image at UENVS  -- kernel R, user R
220	//    - envs itself -- kernel RW, user NONE
221	// LAB 3: Your code here.
222
223	boot_map_region(kern_pgdir, UENVS, PTSIZE, PADDR(envs), PTE_U | PTE_P);
224
225
226
227	//////////////////////////////////////////////////////////////////////
228	// Use the physical memory that 'bootstack' refers to as the kernel
229	// stack.  The kernel stack grows down from virtual address KSTACKTOP.
230	// We consider the entire range from [KSTACKTOP-PTSIZE, KSTACKTOP)
231	// to be the kernel stack, but break this into two pieces:
232	//     * [KSTACKTOP-KSTKSIZE, KSTACKTOP) -- backed by physical memory
233	//     * [KSTACKTOP-PTSIZE, KSTACKTOP-KSTKSIZE) -- not backed; so if
234	//       the kernel overflows its stack, it will fault rather than
235	//       overwrite memory.  Known as a "guard page".
236	//     Permissions: kernel RW, user NONE
237	// Your code goes here:
238	
239	boot_map_region(kern_pgdir, KSTACKTOP-KSTKSIZE, KSTKSIZE, PADDR(bootstack), PTE_W);
240								
241
242
243	//////////////////////////////////////////////////////////////////////
244	// Map all of physical memory at KERNBASE.
245	// Ie.  the VA range [KERNBASE, 2^32) should map to
246	//      the PA range [0, 2^32 - KERNBASE)
247	// We might not have 2^32 - KERNBASE bytes of physical memory, but
248	// we just set up the mapping anyway.
249	// Permissions: kernel RW, user NONE
250	// Your code goes here:
251	
252	boot_map_region(kern_pgdir, KERNBASE, -KERNBASE, 0, PTE_W);
253
254
255
256
257	// Initialize the SMP-related parts of the memory map
258	mem_init_mp();
259
260	// Check that the initial page directory has been set up correctly.
261	check_kern_pgdir();
262
263	// Switch from the minimal entry page directory to the full kern_pgdir
264	// page table we just created.	Our instruction pointer should be
265	// somewhere between KERNBASE and KERNBASE+4MB right now, which is
266	// mapped the same way by both page tables.
267	//
268	// If the machine reboots at this point, you've probably set up your
269	// kern_pgdir wrong.
270	lcr3(PADDR(kern_pgdir));
271
272	check_page_free_list(0);
273
274	// entry.S set the really important flags in cr0 (including enabling
275	// paging).  Here we configure the rest of the flags that we care about.
276	cr0 = rcr0();
277	cr0 |= CR0_PE|CR0_PG|CR0_AM|CR0_WP|CR0_NE|CR0_MP;
278	cr0 &= ~(CR0_TS|CR0_EM);
279	lcr0(cr0);
280
281	// Some more checks, only possible after kern_pgdir is installed.
282	check_page_installed_pgdir();
283}
284
285// Modify mappings in kern_pgdir to support SMP
286//   - Map the per-CPU stacks in the region [KSTACKTOP-PTSIZE, KSTACKTOP)
287//
288static void
289mem_init_mp(void)
290{
291	// Map per-CPU stacks starting at KSTACKTOP, for up to 'NCPU' CPUs.
292	//
293	// For CPU i, use the physical memory that 'percpu_kstacks[i]' refers
294	// to as its kernel stack. CPU i's kernel stack grows down from virtual
295	// address kstacktop_i = KSTACKTOP - i * (KSTKSIZE + KSTKGAP), and is
296	// divided into two pieces, just like the single stack you set up in
297	// mem_init:
298	//     * [kstacktop_i - KSTKSIZE, kstacktop_i)
299	//          -- backed by physical memory
300	//     * [kstacktop_i - (KSTKSIZE + KSTKGAP), kstacktop_i - KSTKSIZE)
301	//          -- not backed; so if the kernel overflows its stack,
302	//             it will fault rather than overwrite another CPU's stack.
303	//             Known as a "guard page".
304	//     Permissions: kernel RW, user NONE
305	//
306	// LAB 4: Your code here:
307
308	
309    for (int i = 0; i < NCPU; ++i) {
310        boot_map_region(kern_pgdir,KSTACKTOP - KSTKSIZE - i * (KSTKSIZE + KSTKGAP),KSTKSIZE,PADDR(percpu_kstacks[i]), PTE_W);
311    }
312
313
314
315
316
317
318}
319
320// --------------------------------------------------------------
321// Tracking of physical pages.
322// The 'pages' array has one 'struct PageInfo' entry per physical page.
323// Pages are reference counted, and free pages are kept on a linked list.
324// --------------------------------------------------------------
325
326//
327// Initialize page structure and memory free list.
328// After this is done, NEVER use boot_alloc again.  ONLY use the page
329// allocator functions below to allocate and deallocate physical
330// memory via the page_free_list.
331//
332void
333page_init(void)
334{
335	// LAB 4:
336	// Change your code to mark the physical page at MPENTRY_PADDR
337	// as in use
338
339	// The example code here marks all physical pages as free.
340	// However this is not truly the case.  What memory is free?
341	//  1) Mark physical page 0 as in use.
342	//     This way we preserve the real-mode IDT and BIOS structures
343	//     in case we ever need them.  (Currently we don't, but...)
344	//  2) The rest of base memory, [PGSIZE, npages_basemem * PGSIZE)
345	//     is free.
346	//  3) Then comes the IO hole [IOPHYSMEM, EXTPHYSMEM), which must
347	//     never be allocated.
348	//  4) Then extended memory [EXTPHYSMEM, ...).
349	//     Some of it is in use, some is free. Where is the kernel
350	//     in physical memory?  Which pages are already in use for
351	//     page tables and other data structures?
352	//
353	// Change the code to reflect this.
354	// NB: DO NOT actually touch the physical memory corresponding to
355	// free pages!
356	
357	size_t i;
358	for (i = 1; i < npages_basemem; i++) {
359		if(page2pa(&pages[i])==MPENTRY_PADDR)
360			continue;
361		pages[i].pp_ref = 0;
362		pages[i].pp_link = page_free_list;
363		page_free_list = &pages[i];
364	}
365
366	int param = (PADDR((char*)pages) + (sizeof(struct PageInfo) * npages)); // FA za zoznamom PI's
367	int rounded = (int)ROUNDUP(param, PGSIZE); // adresa prveho ramca za zoznamom
368 	int med = rounded/PGSIZE; // dostaneme pocet ramcov
369	//int med = (int)ROUNDUP(((char*)envs) + (sizeof(struct Env) * NENV) - 0xf0000000, PGSIZE)/PGSIZE;
370	for (i = med; i < npages; i++) {
371	if(page2pa(&pages[i])==MPENTRY_PADDR)
372			continue;
373		pages[i].pp_ref = 0;
374		pages[i].pp_link = page_free_list;
375		page_free_list = &pages[i];
376	}
377}
378
379//
380// Allocates a physical page.  If (alloc_flags & ALLOC_ZERO), fills the entire
381// returned physical page with '\0' bytes.  Does NOT increment the reference
382// count of the page - the caller must do these if necessary (either explicitly
383// or via page_insert).
384//
385// Be sure to set the pp_link field of the allocated page to NULL so
386// page_free can check for double-free bugs.
387//
388// Returns NULL if out of free memory.
389//
390// Hint: use page2kva and memset
391struct PageInfo *
392page_alloc(int alloc_flags)
393{
394	// Fill this function in
395	if (page_free_list) {
396        	struct PageInfo *ret = page_free_list;	// ulozime si prvy prvok zo zoznamu volnych ramcov na dalsie spracovanie
397       
398        	page_free_list = page_free_list->pp_link; // posunie pointer na zaciatok listu na dalsi prvok
399		ret->pp_link = NULL;
400		if (alloc_flags & ALLOC_ZERO) {
401			memset(page2kva(ret), '\0', PGSIZE);		
402		} 	// page2kva Returns the starting kernel virtual address corresponding to an element of pages[]-zeby adresu stranky ?
403			// viem obist page2kva? vynasobit zaciatok listu PGSIZE a potom pricitat 0xF0000000 ? pojde to?
404
405        	return ret;
406    	}
407	return NULL;
408}
409
410//
411// Return a page to the free list.
412// (This function should only be called when pp->pp_ref reaches 0.)
413//
414void
415page_free(struct PageInfo *pp)
416{
417	// Fill this function in
418	// Hint: You may want to panic if pp->pp_ref is nonzero or
419	// pp->pp_link is not NULL.
420
421	if((pp->pp_ref!=0)) {
422		panic("Page free failed,ref != 0");
423		//pp->pp_link = NULL; 
424		
425	}
426
427	if((pp->pp_link!=NULL)) {
428			panic("Page free failed,link != NULL"); // spadne to na 
429	} 
430		
431    	pp->pp_link = page_free_list;  // link ukazuje na zoznam volnych
432    	page_free_list = pp;  // page_free_list v tomto momente nie je prvy, ale druhy prvok... preto musime 
433			// nastavit zaciatok listu (momentalne pp) do page_free_list
434}
435
436//
437// Decrement the reference count on a page,
438// freeing it if there are no more refs.
439//
440void
441page_decref(struct PageInfo* pp)
442{
443	if (--pp->pp_ref == 0)
444		page_free(pp);
445}
446
447// Given 'pgdir', a pointer to a page directory, pgdir_walk returns
448// a pointer to the page table entry (PTE) for linear address 'va'.
449// This requires walking the two-level page table structure.
450//
451// The relevant page table page might not exist yet.
452// If this is true, and create == false, then pgdir_walk returns NULL.
453// Otherwise, pgdir_walk allocates a new page table page with page_alloc.
454//    - If the allocation fails, pgdir_walk returns NULL.
455//    - Otherwise, the new page's reference count is incremented,
456//	the page is cleared,
457//	and pgdir_walk returns a pointer into the new page table page.
458//
459// Hint 1: you can turn a PageInfo * into the physical address of the
460// page it refers to with page2pa() from kern/pmap.h.
461//
462// Hint 2: the x86 MMU checks permission bits in both the page directory
463// and the page table, so it's safe to leave permissions in the page
464// directory more permissive than strictly necessary.
465//
466// Hint 3: look at inc/mmu.h for useful macros that mainipulate page
467// table and page directory entries.
468//
469pte_t *
470pgdir_walk(pde_t *pgdir, const void *va, int create)
471{
472	pte_t *zac_tab_va;
473	pte_t  *druha_tab_va;
474	
475	//pte_t druha_tab_va =(pte_t*)zac_tab_va + PTX(va);
476	//pte_t *pte_a = &((pte_t*)KADDR(PTE_ADDR(prvy_pte_a)))+PTX(va); //[PTX(va)] malo by tu byt odkazanie na druhu tabulku
477	
478	if(pgdir[PDX(va)] & PTE_P){
479		 zac_tab_va = KADDR(PTE_ADDR(pgdir[PDX(va)]));
480		 druha_tab_va =((pte_t*)zac_tab_va )+ PTX(va);
481		return druha_tab_va;
482	}
483	else {
484		if(create)
485		{
486			struct PageInfo *pgi=page_alloc(ALLOC_ZERO);
487			if(pgi==NULL) return NULL;
488	
489			pgi->pp_ref++;
490			pgdir[PDX(va)] = page2pa(pgi) | PTE_P | PTE_U | PTE_W;//nastavime permiss v pgdir
491			zac_tab_va = KADDR(PTE_ADDR(pgdir[PDX(va)]));
492			druha_tab_va =((pte_t*)zac_tab_va )+ PTX(va);
493			return druha_tab_va;
494			
495		}	
496		else return NULL;
497	}
498}
499
500//
501// Map [va, va+size) of virtual address space to physical [pa, pa+size)
502// in the page table rooted at pgdir.  Size is a multiple of PGSIZE, and
503// va and pa are both page-aligned.
504// Use permission bits perm|PTE_P for the entries.
505//
506// This function is only intended to set up the ``static'' mappings
507// above UTOP. As such, it should *not* change the pp_ref field on the
508// mapped pages.
509//
510// Hint: the TA solution uses pgdir_walk
511static void
512boot_map_region(pde_t *pgdir, uintptr_t va, size_t size, physaddr_t pa, int perm)
513{
514	// Fill this function in
515	int page_count = size/PGSIZE;
516	for (int i = 0; i < page_count; i++) {
517		pte_t* next = pgdir_walk(pgdir, (void*)va, 1);
518		if (next != NULL) {
519			*next = pa | perm | PTE_P;
520			pa = pa + PGSIZE;
521			va = va + PGSIZE;	
522		}
523		else panic("boot_map_region sa dojebal");
524	}
525}
526
527//
528// Map the physical page 'pp' at virtual address 'va'.
529// The permissions (the low 12 bits) of the page table entry
530// should be set to 'perm|PTE_P'.
531//
532// Requirements
533//   - If there is already a page mapped at 'va', it should be page_remove()d.
534//   - If necessary, on demand, a page table should be allocated and inserted
535//     into 'pgdir'.
536//   - pp->pp_ref should be incremented if the insertion succeeds.
537//   - The TLB must be invalidated if a page was formerly present at 'va'.
538//
539// Corner-case hint: Make sure to consider what happens when the same
540// pp is re-inserted at the same virtual address in the same pgdir.
541// However, try not to distinguish this case in your code, as this
542// frequently leads to subtle bugs; there's an elegant way to handle
543// everything in one code path.
544//
545// RETURNS:
546//   0 on success
547//   -E_NO_MEM, if page table couldn't be allocated
548//
549// Hint: The TA solution is implemented using pgdir_walk, page_remove,
550// and page2pa.
551//
552int
553page_insert(pde_t *pgdir, struct PageInfo *pp, void *va, int perm)
554{
555	pte_t* new = pgdir_walk(pgdir,va,1);
556	if(new == NULL) // ak sa nepodarilo vytvorit (nie je pamat)
557		return -E_NO_MEM;
558	
559	pp->pp_ref++;
560	if (*new & PTE_P) { // ak existuje tak zmaze
561		page_remove(pgdir,va);
562	}
563	//pgdir[PDX(va)]=(pte_t*)(pa2page(new) | perm | PTE_P);
564	*new = page2pa(pp) | perm | PTE_P;
565	return 0;	
566}
567
568//
569// Return the page mapped at virtual address 'va'.
570// If pte_store is not zero, then we store in it the address
571// of the pte for this page.  This is used by page_remove and
572// can be used to verify page permissions for syscall arguments,
573// but should not be used by most callers.
574//
575// Return NULL if there is no page mapped at va.
576//
577// Hint: the TA solution uses pgdir_walk and pa2page.
578//
579struct PageInfo *
580page_lookup(pde_t *pgdir, void *va, pte_t **pte_store)
581{
582	pte_t* pte_pa = pgdir_walk(pgdir,va,0);
583	if(pte_pa == NULL || !(*pte_pa & PTE_P)) 
584		return NULL;
585	if(*pte_store != 0) 
586		*pte_store = pte_pa;
587	return pa2page(PTE_ADDR(*pte_pa)); 
588}
589
590//
591// Unmaps the physical page at virtual address 'va'.
592// If there is no physical page at that address, silently does nothing.
593//
594// Details:
595//   - The ref count on the physical page should decrement.
596//   - The physical page should be freed if the refcount reaches 0.
597//   - The pg table entry corresponding to 'va' should be set to 0.
598//     (if such a PTE exists)
599//   - The TLB must be invalidated if you remove an entry from
600//     the page table.
601//
602// Hint: The TA solution is implemented using page_lookup,
603// 	tlb_invalidate, and page_decref.
604//
605void
606page_remove(pde_t *pgdir, void *va)
607{
608	pte_t *pte_store;
609	struct PageInfo *stranka = page_lookup(pgdir, va, &pte_store);
610	if(stranka == NULL) {
611		return;
612	} //stranka neexistuje
613	//funkcia je void,pojde to ?
614	
615	//stranka existuje
616	page_decref(stranka); //moze zavolat page free
617	//pte_t* polozka = (pte_t*)page2pa(stranka);
618	*pte_store = 0;
619	tlb_invalidate(pgdir,va);
620	
621}
622
623//
624// Invalidate a TLB entry, but only if the page tables being
625// edited are the ones currently in use by the processor.
626//
627void
628tlb_invalidate(pde_t *pgdir, void *va)
629{
630	// Flush the entry only if we're modifying the current address space.
631	if (!curenv || curenv->env_pgdir == pgdir)
632		invlpg(va);
633}
634
635//
636// Reserve size bytes in the MMIO region and map [pa,pa+size) at this
637// location.  Return the base of the reserved region.  size does *not*
638// have to be multiple of PGSIZE.
639//
640void *
641mmio_map_region(physaddr_t pa, size_t size)
642{
643	// Where to start the next region.  Initially, this is the
644	// beginning of the MMIO region.  Because this is static, its
645	// value will be preserved between calls to mmio_map_region
646	// (just like nextfree in boot_alloc).
647	static uintptr_t base = MMIOBASE;
648
649	// Reserve size bytes of virtual memory starting at base and
650	// map physical pages [pa,pa+size) to virtual addresses
651	// [base,base+size).  Since this is device memory and not
652	// regular DRAM, you'll have to tell the CPU that it isn't
653	// safe to cache access to this memory.  Luckily, the page
654	// tables provide bits for this purpose; simply create the
655	// mapping with PTE_PCD|PTE_PWT (cache-disable and
656	// write-through) in addition to PTE_W.  (If you're interested
657	// in more details on this, see section 10.5 of IA32 volume
658	// 3A.)
659	//
660	// Be sure to round size up to a multiple of PGSIZE and to
661	// handle if this reservation would overflow MMIOLIM (it's
662	// okay to simply panic if this happens).
663	//
664	// Hint: The staff solution uses boot_map_region.
665	//
666
667	size=ROUNDUP(size,PGSIZE);
668	if(base+size >= MMIOLIM)
669		panic("mmiOregion");	
670	
671	boot_map_region(kern_pgdir,base,size,pa,PTE_PCD|PTE_PWT|PTE_W );
672	uintptr_t tmp = base;	
673	base += size;
674	return (void*)tmp;
675	
676	
677	
678
679
680		
681	// Your code here:
682	//panic("mmio_map_region not implemented");
683}
684
685static uintptr_t user_mem_check_addr;
686
687//
688// Check that an environment is allowed to access the range of memory
689// [va, va+len) with permissions 'perm | PTE_P'.
690// Normally 'perm' will contain PTE_U at least, but this is not required.
691// 'va' and 'len' need not be page-aligned; you must test every page that
692// contains any of that range.  You will test either 'len/PGSIZE',
693// 'len/PGSIZE + 1', or 'len/PGSIZE + 2' pages.
694//
695// A user program can access a virtual address if (1) the address is below
696// ULIM, and (2) the page table gives it permission.  These are exactly
697// the tests you should implement here.
698//
699// If there is an error, set the 'user_mem_check_addr' variable to the first
700// erroneous virtual address.
701//
702// Returns 0 if the user program can access this range of addresses,
703// and -E_FAULT otherwise.
704//
705int
706user_mem_check(struct Env *env, const void *va, size_t len, int perm)
707{
708	// LAB 3: Your code here.
709
710	uint32_t start = (uint32_t)ROUNDDOWN(va,PGSIZE);
711	uint32_t end = (uint32_t)ROUNDUP(va+len,PGSIZE);
712	
713	while (start < end) {
714		
715		pte_t *temp=pgdir_walk(env->env_pgdir, (void*)start, 0);
716		if ((start>=ULIM) || !temp || !(*temp & PTE_P) || ((*temp & perm) != perm))//(start >= ULIM || !temp||   !(*temp | perm | PTE_P)) {
717			{if (start<(uint32_t)va){
718
719				user_mem_check_addr=(uint32_t)va;
720
721			}
722			else{
723				user_mem_check_addr=start;			
724
725			} 
726			return -E_FAULT;
727		}
728		start += PGSIZE;
729	}
730
731	return 0;
732}
733
734//
735// Checks that environment 'env' is allowed to access the range
736// of memory [va, va+len) with permissions 'perm | PTE_U | PTE_P'.
737// If it can, then the function simply returns.
738// If it cannot, 'env' is destroyed and, if env is the current
739// environment, this function will not return.
740//
741void
742user_mem_assert(struct Env *env, const void *va, size_t len, int perm)
743{
744	if (user_mem_check(env, va, len, perm | PTE_U) < 0) {
745		cprintf("[%08x] user_mem_check assertion failure for "
746			"va %08x\n", env->env_id, user_mem_check_addr);
747		env_destroy(env);	// may not return
748	}
749}
750
751
752// --------------------------------------------------------------
753// Checking functions.
754// --------------------------------------------------------------
755
756//
757// Check that the pages on the page_free_list are reasonable.
758//
759static void
760check_page_free_list(bool only_low_memory)
761{
762	struct PageInfo *pp;
763	unsigned pdx_limit = only_low_memory ? 1 : NPDENTRIES;
764	int nfree_basemem = 0, nfree_extmem = 0;
765	char *first_free_page;
766
767	if (!page_free_list)
768		panic("'page_free_list' is a null pointer!");
769
770	if (only_low_memory) {
771		// Move pages with lower addresses first in the free
772		// list, since entry_pgdir does not map all pages.
773		struct PageInfo *pp1, *pp2;
774		struct PageInfo **tp[2] = { &pp1, &pp2 };
775		for (pp = page_free_list; pp; pp = pp->pp_link) {
776			int pagetype = PDX(page2pa(pp)) >= pdx_limit;
777			*tp[pagetype] = pp;
778			tp[pagetype] = &pp->pp_link;
779		}
780		*tp[1] = 0;
781		*tp[0] = pp2;
782		page_free_list = pp1;
783	}
784
785	// if there's a page that shouldn't be on the free list,
786	// try to make sure it eventually causes trouble.
787	for (pp = page_free_list; pp; pp = pp->pp_link)
788		if (PDX(page2pa(pp)) < pdx_limit)
789			memset(page2kva(pp), 0x97, 128);
790
791	first_free_page = (char *) boot_alloc(0);
792	for (pp = page_free_list; pp; pp = pp->pp_link) {
793		// check that we didn't corrupt the free list itself
794		assert(pp >= pages);
795		assert(pp < pages + npages);
796		assert(((char *) pp - (char *) pages) % sizeof(*pp) == 0);
797
798		// check a few pages that shouldn't be on the free list
799		assert(page2pa(pp) != 0);
800		assert(page2pa(pp) != IOPHYSMEM);
801		assert(page2pa(pp) != EXTPHYSMEM - PGSIZE);
802		assert(page2pa(pp) != EXTPHYSMEM);
803		assert(page2pa(pp) < EXTPHYSMEM || (char *) page2kva(pp) >= first_free_page);
804		// (new test for lab 4)
805		assert(page2pa(pp) != MPENTRY_PADDR);
806
807		if (page2pa(pp) < EXTPHYSMEM)
808			++nfree_basemem;
809		else
810			++nfree_extmem;
811	}
812
813	assert(nfree_basemem > 0);
814	assert(nfree_extmem > 0);
815
816	cprintf("check_page_free_list() succeeded!\n");
817}
818
819//
820// Check the physical page allocator (page_alloc(), page_free(),
821// and page_init()).
822//
823static void
824check_page_alloc(void)
825{
826	struct PageInfo *pp, *pp0, *pp1, *pp2;
827	int nfree;
828	struct PageInfo *fl;
829	char *c;
830	int i;
831
832	if (!pages)
833		panic("'pages' is a null pointer!");
834
835	// check number of free pages
836	for (pp = page_free_list, nfree = 0; pp; pp = pp->pp_link)
837		++nfree;
838
839	// should be able to allocate three pages
840	pp0 = pp1 = pp2 = 0;
841	assert((pp0 = page_alloc(0)));
842	assert((pp1 = page_alloc(0)));
843	assert((pp2 = page_alloc(0)));
844
845	assert(pp0);
846	assert(pp1 && pp1 != pp0);
847	assert(pp2 && pp2 != pp1 && pp2 != pp0);
848	assert(page2pa(pp0) < npages*PGSIZE);
849	assert(page2pa(pp1) < npages*PGSIZE);
850	assert(page2pa(pp2) < npages*PGSIZE);
851
852	// temporarily steal the rest of the free pages
853	fl = page_free_list;
854	page_free_list = 0;
855
856	// should be no free memory
857	assert(!page_alloc(0));
858
859	// free and re-allocate?
860	page_free(pp0);
861	page_free(pp1);
862	page_free(pp2);
863	pp0 = pp1 = pp2 = 0;
864	assert((pp0 = page_alloc(0)));
865	assert((pp1 = page_alloc(0)));
866	assert((pp2 = page_alloc(0)));
867	assert(pp0);
868	assert(pp1 && pp1 != pp0);
869	assert(pp2 && pp2 != pp1 && pp2 != pp0);
870	assert(!page_alloc(0));
871
872	// test flags
873	memset(page2kva(pp0), 1, PGSIZE);
874	page_free(pp0);
875	assert((pp = page_alloc(ALLOC_ZERO)));
876	assert(pp && pp0 == pp);
877	c = page2kva(pp);
878	for (i = 0; i < PGSIZE; i++)
879		assert(c[i] == 0);
880
881	// give free list back
882	page_free_list = fl;
883
884	// free the pages we took
885	page_free(pp0);
886	page_free(pp1);
887	page_free(pp2);
888
889	// number of free pages should be the same
890	for (pp = page_free_list; pp; pp = pp->pp_link)
891		--nfree;
892	assert(nfree == 0);
893
894	cprintf("check_page_alloc() succeeded!\n");
895}
896
897//
898// Checks that the kernel part of virtual address space
899// has been setup roughly correctly (by mem_init()).
900//
901// This function doesn't test every corner case,
902// but it is a pretty good sanity check.
903//
904
905static void
906check_kern_pgdir(void)
907{
908	uint32_t i, n;
909	pde_t *pgdir;
910
911	pgdir = kern_pgdir;
912
913	// check pages array
914	n = ROUNDUP(npages*sizeof(struct PageInfo), PGSIZE);
915	for (i = 0; i < n; i += PGSIZE)
916		assert(check_va2pa(pgdir, UPAGES + i) == PADDR(pages) + i);
917
918	// check envs array (new test for lab 3)
919	n = ROUNDUP(NENV*sizeof(struct Env), PGSIZE);
920	for (i = 0; i < n; i += PGSIZE)
921		assert(check_va2pa(pgdir, UENVS + i) == PADDR(envs) + i);
922
923	// check phys mem
924	for (i = 0; i < npages * PGSIZE; i += PGSIZE)
925		assert(check_va2pa(pgdir, KERNBASE + i) == i);
926
927	// check kernel stack
928	// (updated in lab 4 to check per-CPU kernel stacks)
929	for (n = 0; n < NCPU; n++) {
930		uint32_t base = KSTACKTOP - (KSTKSIZE + KSTKGAP) * (n + 1);
931		for (i = 0; i < KSTKSIZE; i += PGSIZE)
932			assert(check_va2pa(pgdir, base + KSTKGAP + i)
933				== PADDR(percpu_kstacks[n]) + i);
934		for (i = 0; i < KSTKGAP; i += PGSIZE)
935			assert(check_va2pa(pgdir, base + i) == ~0);
936	}
937
938	// check PDE permissions
939	for (i = 0; i < NPDENTRIES; i++) {
940		switch (i) {
941		case PDX(UVPT):
942		case PDX(KSTACKTOP-1):
943		case PDX(UPAGES):
944		case PDX(UENVS):
945		case PDX(MMIOBASE):
946			assert(pgdir[i] & PTE_P);
947			break;
948		default:
949			if (i >= PDX(KERNBASE)) {
950				assert(pgdir[i] & PTE_P);
951				assert(pgdir[i] & PTE_W);
952			} else
953				assert(pgdir[i] == 0);
954			break;
955		}
956	}
957	cprintf("check_kern_pgdir() succeeded!\n");
958}
959
960// This function returns the physical address of the page containing 'va',
961// defined by the page directory 'pgdir'.  The hardware normally performs
962// this functionality for us!  We define our own version to help check
963// the check_kern_pgdir() function; it shouldn't be used elsewhere.
964
965static physaddr_t
966check_va2pa(pde_t *pgdir, uintptr_t va)
967{
968	pte_t *p;
969
970	pgdir = &pgdir[PDX(va)];
971	if (!(*pgdir & PTE_P))
972		return ~0;
973	p = (pte_t*) KADDR(PTE_ADDR(*pgdir));
974	if (!(p[PTX(va)] & PTE_P))
975		return ~0;
976	return PTE_ADDR(p[PTX(va)]);
977}
978
979
980// check page_insert, page_remove, &c
981static void
982check_page(void)
983{
984	struct PageInfo *pp, *pp0, *pp1, *pp2;
985	struct PageInfo *fl;
986	pte_t *ptep, *ptep1;
987	void *va;
988	uintptr_t mm1, mm2;
989	int i;
990	extern pde_t entry_pgdir[];
991
992	// should be able to allocate three pages
993	pp0 = pp1 = pp2 = 0;
994	assert((pp0 = page_alloc(0)));
995	assert((pp1 = page_alloc(0)));
996	assert((pp2 = page_alloc(0)));
997
998	assert(pp0);
999	assert(pp1 && pp1 != pp0);
1000	assert(pp2 && pp2 != pp1 && pp2 != pp0);
1001
1002	// temporarily steal the rest of the free pages
1003	fl = page_free_list;
1004	page_free_list = 0;
1005
1006	// should be no free memory
1007	assert(!page_alloc(0));
1008
1009	// there is no page allocated at address 0
1010	assert(page_lookup(kern_pgdir, (void *) 0x0, &ptep) == NULL);
1011
1012	// there is no free memory, so we can't allocate a page table
1013	assert(page_insert(kern_pgdir, pp1, 0x0, PTE_W) < 0);
1014
1015	// free pp0 and try again: pp0 should be used for page table
1016	page_free(pp0);
1017	assert(page_insert(kern_pgdir, pp1, 0x0, PTE_W) == 0);
1018	assert(PTE_ADDR(kern_pgdir[0]) == page2pa(pp0));
1019	assert(check_va2pa(kern_pgdir, 0x0) == page2pa(pp1));
1020	assert(pp1->pp_ref == 1);
1021	assert(pp0->pp_ref == 1);
1022
1023	// should be able to map pp2 at PGSIZE because pp0 is already allocated for page table
1024	assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W) == 0);
1025	assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp2));
1026	assert(pp2->pp_ref == 1);
1027
1028	// should be no free memory
1029	assert(!page_alloc(0));
1030
1031	// should be able to map pp2 at PGSIZE because it's already there
1032	assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W) == 0);
1033	assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp2));
1034	assert(pp2->pp_ref == 1);
1035
1036	// pp2 should NOT be on the free list
1037	// could happen in ref counts are handled sloppily in page_insert
1038	assert(!page_alloc(0));
1039
1040	// check that pgdir_walk returns a pointer to the pte
1041	ptep = (pte_t *) KADDR(PTE_ADDR(kern_pgdir[PDX(PGSIZE)]));
1042	assert(pgdir_walk(kern_pgdir, (void*)PGSIZE, 0) == ptep+PTX(PGSIZE));
1043
1044	// should be able to change permissions too.
1045	assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W|PTE_U) == 0);
1046	assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp2));
1047	assert(pp2->pp_ref == 1);
1048	assert(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_U);
1049	assert(kern_pgdir[0] & PTE_U);
1050
1051	// should be able to remap with fewer permissions
1052	assert(page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W) == 0);
1053	assert(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_W);
1054	assert(!(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_U));
1055
1056	// should not be able to map at PTSIZE because need free page for page table
1057	assert(page_insert(kern_pgdir, pp0, (void*) PTSIZE, PTE_W) < 0);
1058
1059	// insert pp1 at PGSIZE (replacing pp2)
1060	assert(page_insert(kern_pgdir, pp1, (void*) PGSIZE, PTE_W) == 0);
1061	assert(!(*pgdir_walk(kern_pgdir, (void*) PGSIZE, 0) & PTE_U));
1062
1063	// should have pp1 at both 0 and PGSIZE, pp2 nowhere, ...
1064	assert(check_va2pa(kern_pgdir, 0) == page2pa(pp1));
1065	assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp1));
1066	// ... and ref counts should reflect this
1067	assert(pp1->pp_ref == 2);
1068	assert(pp2->pp_ref == 0);
1069
1070	// pp2 should be returned by page_alloc
1071	assert((pp = page_alloc(0)) && pp == pp2);
1072
1073	// unmapping pp1 at 0 should keep pp1 at PGSIZE
1074	page_remove(kern_pgdir, 0x0);
1075	assert(check_va2pa(kern_pgdir, 0x0) == ~0);
1076	assert(check_va2pa(kern_pgdir, PGSIZE) == page2pa(pp1));
1077	assert(pp1->pp_ref == 1);
1078	assert(pp2->pp_ref == 0);
1079
1080	// test re-inserting pp1 at PGSIZE
1081	assert(page_insert(kern_pgdir, pp1, (void*) PGSIZE, 0) == 0);
1082	assert(pp1->pp_ref);
1083	assert(pp1->pp_link == NULL);
1084
1085	// unmapping pp1 at PGSIZE should free it
1086	page_remove(kern_pgdir, (void*) PGSIZE);
1087	assert(check_va2pa(kern_pgdir, 0x0) == ~0);
1088	assert(check_va2pa(kern_pgdir, PGSIZE) == ~0);
1089	assert(pp1->pp_ref == 0);
1090	assert(pp2->pp_ref == 0);
1091
1092	// so it should be returned by page_alloc
1093	assert((pp = page_alloc(0)) && pp == pp1);
1094
1095	// should be no free memory
1096	assert(!page_alloc(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	// check pointer arithmetic in pgdir_walk
1105	page_free(pp0);
1106	va = (void*)(PGSIZE * NPDENTRIES + PGSIZE);
1107	ptep = pgdir_walk(kern_pgdir, va, 1);
1108	ptep1 = (pte_t *) KADDR(PTE_ADDR(kern_pgdir[PDX(va)]));
1109	assert(ptep == ptep1 + PTX(va));
1110	kern_pgdir[PDX(va)] = 0;
1111	pp0->pp_ref = 0;
1112
1113	// check that new page tables get cleared
1114	memset(page2kva(pp0), 0xFF, PGSIZE);
1115	page_free(pp0);
1116	pgdir_walk(kern_pgdir, 0x0, 1);
1117	ptep = (pte_t *) page2kva(pp0);
1118	for(i=0; i<NPTENTRIES; i++)
1119		assert((ptep[i] & PTE_P) == 0);
1120	kern_pgdir[0] = 0;
1121	pp0->pp_ref = 0;
1122
1123	// give free list back
1124	page_free_list = fl;
1125
1126	// free the pages we took
1127	page_free(pp0);
1128	page_free(pp1);
1129	page_free(pp2);
1130
1131	// test mmio_map_region
1132	mm1 = (uintptr_t) mmio_map_region(0, 4097);
1133	mm2 = (uintptr_t) mmio_map_region(0, 4096);
1134	// check that they're in the right region
1135	assert(mm1 >= MMIOBASE && mm1 + 8096 < MMIOLIM);
1136	assert(mm2 >= MMIOBASE && mm2 + 8096 < MMIOLIM);
1137	// check that they're page-aligned
1138	assert(mm1 % PGSIZE == 0 && mm2 % PGSIZE == 0);
1139	// check that they don't overlap
1140	assert(mm1 + 8096 <= mm2);
1141	// check page mappings
1142	assert(check_va2pa(kern_pgdir, mm1) == 0);
1143	assert(check_va2pa(kern_pgdir, mm1+PGSIZE) == PGSIZE);
1144	assert(check_va2pa(kern_pgdir, mm2) == 0);
1145	assert(check_va2pa(kern_pgdir, mm2+PGSIZE) == ~0);
1146	// check permissions
1147	assert(*pgdir_walk(kern_pgdir, (void*) mm1, 0) & (PTE_W|PTE_PWT|PTE_PCD));
1148	assert(!(*pgdir_walk(kern_pgdir, (void*) mm1, 0) & PTE_U));
1149	// clear the mappings
1150	*pgdir_walk(kern_pgdir, (void*) mm1, 0) = 0;
1151	*pgdir_walk(kern_pgdir, (void*) mm1 + PGSIZE, 0) = 0;
1152	*pgdir_walk(kern_pgdir, (void*) mm2, 0) = 0;
1153
1154	cprintf("check_page() succeeded!\n");
1155}
1156
1157// check page_insert, page_remove, &c, with an installed kern_pgdir
1158static void
1159check_page_installed_pgdir(void)
1160{
1161	struct PageInfo *pp, *pp0, *pp1, *pp2;
1162	struct PageInfo *fl;
1163	pte_t *ptep, *ptep1;
1164	uintptr_t va;
1165	int i;
1166
1167	// check that we can read and write installed pages
1168	pp1 = pp2 = 0;
1169	assert((pp0 = page_alloc(0)));
1170	assert((pp1 = page_alloc(0)));
1171	assert((pp2 = page_alloc(0)));
1172	page_free(pp0);
1173	memset(page2kva(pp1), 1, PGSIZE);
1174	memset(page2kva(pp2), 2, PGSIZE);
1175	page_insert(kern_pgdir, pp1, (void*) PGSIZE, PTE_W);
1176	assert(pp1->pp_ref == 1);
1177	assert(*(uint32_t *)PGSIZE == 0x01010101U);
1178	page_insert(kern_pgdir, pp2, (void*) PGSIZE, PTE_W);
1179	assert(*(uint32_t *)PGSIZE == 0x02020202U);
1180	assert(pp2->pp_ref == 1);
1181	assert(pp1->pp_ref == 0);
1182	*(uint32_t *)PGSIZE = 0x03030303U;
1183	assert(*(uint32_t *)page2kva(pp2) == 0x03030303U);
1184	page_remove(kern_pgdir, (void*) PGSIZE);
1185	assert(pp2->pp_ref == 0);
1186
1187	// forcibly take pp0 back
1188	assert(PTE_ADDR(kern_pgdir[0]) == page2pa(pp0));
1189	kern_pgdir[0] = 0;
1190	assert(pp0->pp_ref == 1);
1191	pp0->pp_ref = 0;
1192
1193	// free the pages we took
1194	page_free(pp0);
1195
1196	cprintf("check_page_installed_pgdir() succeeded!\n");
1197}