kern
view src/vm.c @ 24:53588744382c
switched the vm to use recursive page tables
| author | John Tsiombikas <nuclear@member.fsf.org> |
|---|---|
| date | Tue, 05 Apr 2011 02:09:02 +0300 |
| parents | 5454cee245a3 |
| children | 9939a6d7a45a |
line source
1 #include <stdio.h>
2 #include <string.h>
3 #include <inttypes.h>
4 #include "vm.h"
5 #include <stdio.h>
6 #include "intr.h"
7 #include "mem.h"
8 #include "panic.h"
11 #define KMEM_START 0xc0000000
12 #define IDMAP_START 0xa0000
14 #define PGDIR_ADDR 0xfffff000
15 #define PGTBL_BASE (0xffffffff - 4096 * 1024 + 1)
16 #define PGTBL(x) ((uint32_t*)(PGTBL_BASE + PGSIZE * (x)))
18 #define ATTR_PGDIR_MASK 0x3f
19 #define ATTR_PGTBL_MASK 0x1ff
20 #define ADDR_PGENT_MASK 0xfffff000
22 #define PAGEFAULT 14
25 struct page_range {
26 int start, end;
27 struct page_range *next;
28 };
30 /* defined in vm-asm.S */
31 void enable_paging(void);
32 void disable_paging(void);
33 int get_paging_status(void);
34 void set_pgdir_addr(uint32_t addr);
35 void flush_tlb(void);
36 void flush_tlb_addr(uint32_t addr);
37 #define flush_tlb_page(p) flush_tlb_addr(PAGE_TO_ADDR(p))
38 uint32_t get_fault_addr(void);
40 static void coalesce(struct page_range *low, struct page_range *mid, struct page_range *high);
41 static void pgfault(int inum, uint32_t err);
42 static struct page_range *alloc_node(void);
43 static void free_node(struct page_range *node);
45 /* page directory */
46 static uint32_t *pgdir;
48 /* 2 lists of free ranges, for kernel memory and user memory */
49 static struct page_range *pglist[2];
50 /* list of free page_range structures to be used in the lists */
51 static struct page_range *node_pool;
52 /* the first page range for the whole kernel address space, to get things started */
53 static struct page_range first_node;
56 void init_vm(struct mboot_info *mb)
57 {
58 uint32_t idmap_end;
60 /* initialize the physical memory map and allocator */
61 init_mem(mb);
63 /* setup the page tables */
64 pgdir = (uint32_t*)alloc_phys_page();
65 memset(pgdir, 0, PGSIZE);
66 set_pgdir_addr((uint32_t)pgdir);
68 /* map the video memory and kernel code 1-1 */
69 get_kernel_mem_range(0, &idmap_end);
70 map_mem_range(IDMAP_START, idmap_end - IDMAP_START, IDMAP_START, 0);
72 /* make the last page directory entry point to the page directory */
73 pgdir[1023] = ((uint32_t)pgdir & ADDR_PGENT_MASK) | PG_PRESENT;
74 pgdir = (uint32_t*)PGDIR_ADDR;
76 /* set the page fault handler */
77 interrupt(PAGEFAULT, pgfault);
79 /* we can enable paging now */
80 enable_paging();
82 /* initialize the virtual page allocator */
83 node_pool = 0;
85 first_node.start = ADDR_TO_PAGE(KMEM_START);
86 first_node.end = PAGE_COUNT;
87 first_node.next = 0;
88 pglist[MEM_KERNEL] = &first_node;
90 pglist[MEM_USER] = alloc_node();
91 pglist[MEM_USER]->start = 0;
92 pglist[MEM_USER]->end = ADDR_TO_PAGE(KMEM_START);
93 pglist[MEM_USER]->next = 0;
94 }
96 /* if ppage == -1 we allocate a physical page by calling alloc_phys_page */
97 int map_page(int vpage, int ppage, unsigned int attr)
98 {
99 uint32_t *pgtbl;
100 int diridx, pgidx, pgon;
102 pgon = get_paging_status();
104 if(ppage < 0) {
105 uint32_t addr = alloc_phys_page();
106 if(!addr) {
107 return -1;
108 }
109 ppage = ADDR_TO_PAGE(addr);
110 }
112 diridx = PAGE_TO_PGTBL(vpage);
113 pgidx = PAGE_TO_PGTBL_PG(vpage);
115 if(!(pgdir[diridx] & PG_PRESENT)) {
116 uint32_t addr = alloc_phys_page();
117 pgdir[diridx] = addr | (attr & ATTR_PGDIR_MASK) | PG_PRESENT;
119 pgtbl = pgon ? PGTBL(diridx) : (uint32_t*)addr;
120 memset(pgtbl, 0, PGSIZE);
121 } else {
122 if(pgon) {
123 pgtbl = PGTBL(diridx);
124 } else {
125 pgtbl = (uint32_t*)(pgdir[diridx] & ADDR_PGENT_MASK);
126 }
127 }
129 pgtbl[pgidx] = PAGE_TO_ADDR(ppage) | (attr & ATTR_PGTBL_MASK) | PG_PRESENT;
130 flush_tlb_page(vpage);
132 return 0;
133 }
135 void unmap_page(int vpage)
136 {
137 uint32_t *pgtbl;
138 int diridx = PAGE_TO_PGTBL(vpage);
139 int pgidx = PAGE_TO_PGTBL_PG(vpage);
141 if(!(pgdir[diridx] & PG_PRESENT)) {
142 goto err;
143 }
144 pgtbl = (uint32_t*)(pgdir[diridx] & ADDR_PGENT_MASK);
146 if(!(pgtbl[pgidx] & PG_PRESENT)) {
147 goto err;
148 }
149 pgtbl[pgidx] = 0;
150 flush_tlb_page(vpage);
152 return;
153 err:
154 printf("unmap_page(%d): page already not mapped\n", vpage);
155 }
157 /* if ppg_start is -1, we allocate physical pages to map with alloc_phys_page() */
158 int map_page_range(int vpg_start, int pgcount, int ppg_start, unsigned int attr)
159 {
160 int i, phys_pg;
161 uint32_t paddr;
163 for(i=0; i<pgcount; i++) {
164 if(ppg_start < 0) {
165 if(!(paddr = alloc_phys_page())) {
166 return -1;
167 }
168 phys_pg = ADDR_TO_PAGE(paddr);
169 } else {
170 phys_pg = ppg_start + i;
171 }
173 map_page(vpg_start + i, phys_pg, attr);
174 }
175 return 0;
176 }
178 /* if paddr is 0, we allocate physical pages with alloc_phys_page() */
179 int map_mem_range(uint32_t vaddr, size_t sz, uint32_t paddr, unsigned int attr)
180 {
181 int vpg_start, ppg_start, num_pages;
183 if(!sz) return -1;
185 if(ADDR_TO_PGOFFS(paddr)) {
186 panic("map_mem_range called with unaligned physical address: %x\n", paddr);
187 }
189 vpg_start = ADDR_TO_PAGE(vaddr);
190 ppg_start = paddr > 0 ? ADDR_TO_PAGE(paddr) : -1;
191 num_pages = ADDR_TO_PAGE(sz) + 1;
193 return map_page_range(vpg_start, num_pages, ppg_start, attr);
194 }
196 uint32_t virt_to_phys(uint32_t vaddr)
197 {
198 uint32_t pgaddr, *pgtbl;
199 int diridx = ADDR_TO_PGTBL(vaddr);
200 int pgidx = ADDR_TO_PGTBL_PG(vaddr);
202 if(!(pgdir[diridx] & PG_PRESENT)) {
203 panic("virt_to_phys(%x): page table %d not present\n", vaddr, diridx);
204 }
205 pgtbl = (uint32_t*)(pgdir[diridx] & PGENT_ADDR_MASK);
207 if(!(pgtbl[pgidx] & PG_PRESENT)) {
208 panic("virt_to_phys(%x): page %d not present\n", vaddr, ADDR_TO_PAGE(vaddr));
209 }
210 pgaddr = pgtbl[pgidx] & PGENT_ADDR_MASK;
212 return pgaddr | ADDR_TO_PGOFFS(vaddr);
213 }
215 /* allocate a contiguous block of virtual memory pages along with
216 * backing physical memory for them, and update the page table.
217 */
218 int pgalloc(int num, int area)
219 {
220 int ret = -1;
221 struct page_range *node, *prev, dummy;
223 dummy.next = pglist[area];
224 node = pglist[area];
225 prev = &dummy;
227 while(node) {
228 if(node->end - node->start >= num) {
229 ret = node->start;
230 node->start += num;
232 if(node->start == node->end) {
233 prev->next = node->next;
234 node->next = 0;
236 if(node == pglist[area]) {
237 pglist[area] = 0;
238 }
239 free_node(node);
240 }
241 break;
242 }
244 prev = node;
245 node = node->next;
246 }
248 if(ret >= 0) {
249 /* allocate physical storage and map */
250 if(map_page_range(ret, num, -1, 0) == -1) {
251 ret = -1;
252 }
253 }
255 return ret;
256 }
258 void pgfree(int start, int num)
259 {
260 int area, end;
261 struct page_range *node, *new, *prev, *next;
263 if(!(new = alloc_node())) {
264 panic("pgfree: can't allocate new page_range node to add the freed pages\n");
265 }
266 new->start = start;
267 end = new->end = start + num;
269 area = PAGE_TO_ADDR(start) >= KMEM_START ? MEM_KERNEL : MEM_USER;
271 if(!pglist[area] || pglist[area]->start > start) {
272 next = new->next = pglist[area];
273 pglist[area] = new;
274 prev = 0;
276 } else {
278 prev = 0;
279 node = pglist[area];
280 next = node ? node->next : 0;
282 while(node) {
283 if(!next || next->start > start) {
284 /* place here, after node */
285 new->next = next;
286 node->next = new;
287 prev = node; /* needed by coalesce after the loop */
288 break;
289 }
291 prev = node;
292 node = next;
293 next = node ? node->next : 0;
294 }
295 }
297 coalesce(prev, new, next);
298 }
300 static void coalesce(struct page_range *low, struct page_range *mid, struct page_range *high)
301 {
302 if(high) {
303 if(mid->end == high->start) {
304 mid->end = high->end;
305 mid->next = high->next;
306 free_node(high);
307 }
308 }
310 if(low) {
311 if(low->end == mid->start) {
312 low->end += mid->end;
313 low->next = mid->next;
314 free_node(mid);
315 }
316 }
317 }
319 static void pgfault(int inum, uint32_t err)
320 {
321 printf("~~~~ PAGE FAULT ~~~~\n");
323 printf("fault address: %x\n", get_fault_addr());
325 if(err & PG_PRESENT) {
326 if(err & 8) {
327 printf("reserved bit set in some paging structure\n");
328 } else {
329 printf("%s protection violation ", (err & PG_WRITABLE) ? "write" : "read");
330 printf("in %s mode\n", err & PG_USER ? "user" : "kernel");
331 }
332 } else {
333 printf("page not present\n");
334 }
336 panic("unhandled page fault\n");
337 }
339 /* --- page range list node management --- */
340 #define NODES_IN_PAGE (PGSIZE / sizeof(struct page_range))
342 static struct page_range *alloc_node(void)
343 {
344 struct page_range *node;
345 int pg, i;
347 if(node_pool) {
348 node = node_pool;
349 node_pool = node_pool->next;
350 printf("alloc_node -> %x\n", (unsigned int)node);
351 return node;
352 }
354 /* no node structures in the pool, we need to allocate a new page,
355 * split it up into node structures, add them in the pool, and
356 * allocate one of them.
357 */
358 if(!(pg = pgalloc(1, MEM_KERNEL))) {
359 panic("ran out of physical memory while allocating VM range structures\n");
360 }
361 node_pool = (struct page_range*)PAGE_TO_ADDR(pg);
363 /* link them up, skip the first as we'll just allocate it anyway */
364 for(i=2; i<NODES_IN_PAGE; i++) {
365 node_pool[i - 1].next = node_pool + i;
366 }
367 node_pool[NODES_IN_PAGE - 1].next = 0;
369 /* grab the first and return it */
370 node = node_pool++;
371 printf("alloc_node -> %x\n", (unsigned int)node);
372 return node;
373 }
375 static void free_node(struct page_range *node)
376 {
377 node->next = node_pool;
378 node_pool = node;
379 printf("free_node\n");
380 }
383 void dbg_print_vm(int area)
384 {
385 struct page_range *node = pglist[area];
386 int last = area == MEM_USER ? 0 : ADDR_TO_PAGE(KMEM_START);
388 printf("%s vm space\n", area == MEM_USER ? "user" : "kernel");
390 while(node) {
391 if(node->start > last) {
392 printf(" vm-used: %x -> %x\n", PAGE_TO_ADDR(last), PAGE_TO_ADDR(node->start));
393 }
395 printf(" vm-free: %x -> ", PAGE_TO_ADDR(node->start));
396 if(node->end >= PAGE_COUNT) {
397 printf("END\n");
398 } else {
399 printf("%x\n", PAGE_TO_ADDR(node->end));
400 }
402 last = node->end;
403 node = node->next;
404 }
405 }