exec.c

   1 /*
   2  *  virtual page mapping and translated block handling
   3  *
   4  *  Copyright (c) 2003 Fabrice Bellard
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20 #include <stdlib.h>
  21 #include <stdio.h>
  22 #include <stdarg.h>
  23 #include <string.h>
  24 #include <errno.h>
  25 #include <unistd.h>
  26 #include <inttypes.h>
  27 #include <sys/mman.h>
  28
  29 #include "cpu-i386.h"
  30
  31 //#define DEBUG_TB_INVALIDATE
  32 #define DEBUG_FLUSH
  33
  34 /* make various TB consistency checks */
  35 //#define DEBUG_TB_CHECK
  36
  37 /* threshold to flush the translated code buffer */
  38 #define CODE_GEN_BUFFER_MAX_SIZE (CODE_GEN_BUFFER_SIZE - CODE_GEN_MAX_SIZE)
  39
  40 #define CODE_GEN_MAX_BLOCKS    (CODE_GEN_BUFFER_SIZE / 64)
  41
  42 TranslationBlock tbs[CODE_GEN_MAX_BLOCKS];
  43 TranslationBlock *tb_hash[CODE_GEN_HASH_SIZE];
  44 int nb_tbs;
  45 /* any access to the tbs or the page table must use this lock */
  46 spinlock_t tb_lock = SPIN_LOCK_UNLOCKED;
  47
  48 uint8_t code_gen_buffer[CODE_GEN_BUFFER_SIZE];
  49 uint8_t *code_gen_ptr;
  50
  51 /* XXX: pack the flags in the low bits of the pointer ? */
  52 typedef struct PageDesc {
  53     unsigned long flags;
  54     TranslationBlock *first_tb;
  55 } PageDesc;
  56
  57 #define L2_BITS 10
  58 #define L1_BITS (32 - L2_BITS - TARGET_PAGE_BITS)
  59
  60 #define L1_SIZE (1 << L1_BITS)
  61 #define L2_SIZE (1 << L2_BITS)
  62
  63 static void tb_invalidate_page(unsigned long address);
  64
  65 unsigned long real_host_page_size;
  66 unsigned long host_page_bits;
  67 unsigned long host_page_size;
  68 unsigned long host_page_mask;
  69
  70 static PageDesc *l1_map[L1_SIZE];
  71
  72 void page_init(void)
  73 {
  74     /* NOTE: we can always suppose that host_page_size >=
  75        TARGET_PAGE_SIZE */
  76     real_host_page_size = getpagesize();
  77     if (host_page_size == 0)
  78         host_page_size = real_host_page_size;
  79     if (host_page_size < TARGET_PAGE_SIZE)
  80         host_page_size = TARGET_PAGE_SIZE;
  81     host_page_bits = 0;
  82     while ((1 << host_page_bits) < host_page_size)
  83         host_page_bits++;
  84     host_page_mask = ~(host_page_size - 1);
  85 }
  86
  87 /* dump memory mappings */
  88 void page_dump(FILE *f)
  89 {
  90     unsigned long start, end;
  91     int i, j, prot, prot1;
  92     PageDesc *p;
  93
  94     fprintf(f, "%-8s %-8s %-8s %s\n",
  95             "start", "end", "size", "prot");
  96     start = -1;
  97     end = -1;
  98     prot = 0;
  99     for(i = 0; i <= L1_SIZE; i++) {
 100         if (i < L1_SIZE)
 101             p = l1_map[i];
 102         else
 103             p = NULL;
 104         for(j = 0;j < L2_SIZE; j++) {
 105             if (!p)
 106                 prot1 = 0;
 107             else
 108                 prot1 = p[j].flags;
 109             if (prot1 != prot) {
 110                 end = (i << (32 - L1_BITS)) | (j << TARGET_PAGE_BITS);
 111                 if (start != -1) {
 112                     fprintf(f, "%08lx-%08lx %08lx %c%c%c\n",
 113                             start, end, end - start,
 114                             prot & PAGE_READ ? 'r' : '-',
 115                             prot & PAGE_WRITE ? 'w' : '-',
 116                             prot & PAGE_EXEC ? 'x' : '-');
 117                 }
 118                 if (prot1 != 0)
 119                     start = end;
 120                 else
 121                     start = -1;
 122                 prot = prot1;
 123             }
 124             if (!p)
 125                 break;
 126         }
 127     }
 128 }
 129
 130 static inline PageDesc *page_find_alloc(unsigned int index)
 131 {
 132     PageDesc **lp, *p;
 133
 134     lp = &l1_map[index >> L2_BITS];
 135     p = *lp;
 136     if (!p) {
 137         /* allocate if not found */
 138         p = malloc(sizeof(PageDesc) * L2_SIZE);
 139         memset(p, 0, sizeof(PageDesc) * L2_SIZE);
 140         *lp = p;
 141     }
 142     return p + (index & (L2_SIZE - 1));
 143 }
 144
 145 static inline PageDesc *page_find(unsigned int index)
 146 {
 147     PageDesc *p;
 148
 149     p = l1_map[index >> L2_BITS];
 150     if (!p)
 151         return 0;
 152     return p + (index & (L2_SIZE - 1));
 153 }
 154
 155 int page_get_flags(unsigned long address)
 156 {
 157     PageDesc *p;
 158
 159     p = page_find(address >> TARGET_PAGE_BITS);
 160     if (!p)
 161         return 0;
 162     return p->flags;
 163 }
 164
 165 /* modify the flags of a page and invalidate the code if
 166    necessary. The flag PAGE_WRITE_ORG is positionned automatically
 167    depending on PAGE_WRITE */
 168 void page_set_flags(unsigned long start, unsigned long end, int flags)
 169 {
 170     PageDesc *p;
 171     unsigned long addr;
 172
 173     start = start & TARGET_PAGE_MASK;
 174     end = TARGET_PAGE_ALIGN(end);
 175     if (flags & PAGE_WRITE)
 176         flags |= PAGE_WRITE_ORG;
 177     spin_lock(&tb_lock);
 178     for(addr = start; addr < end; addr += TARGET_PAGE_SIZE) {
 179         p = page_find_alloc(addr >> TARGET_PAGE_BITS);
 180         /* if the write protection is set, then we invalidate the code
 181            inside */
 182         if (!(p->flags & PAGE_WRITE) &&
 183             (flags & PAGE_WRITE) &&
 184             p->first_tb) {
 185             tb_invalidate_page(addr);
 186         }
 187         p->flags = flags;
 188     }
 189     spin_unlock(&tb_lock);
 190 }
 191
 192 void cpu_x86_tblocks_init(void)
 193 {
 194     if (!code_gen_ptr) {
 195         code_gen_ptr = code_gen_buffer;
 196     }
 197 }
 198
 199 /* set to NULL all the 'first_tb' fields in all PageDescs */
 200 static void page_flush_tb(void)
 201 {
 202     int i, j;
 203     PageDesc *p;
 204
 205     for(i = 0; i < L1_SIZE; i++) {
 206         p = l1_map[i];
 207         if (p) {
 208             for(j = 0; j < L2_SIZE; j++)
 209                 p[j].first_tb = NULL;
 210         }
 211     }
 212 }
 213
 214 /* flush all the translation blocks */
 215 void tb_flush(void)
 216 {
 217     int i;
 218 #ifdef DEBUG_FLUSH
 219     printf("qemu: flush code_size=%d nb_tbs=%d avg_tb_size=%d\n",
 220            code_gen_ptr - code_gen_buffer,
 221            nb_tbs,
 222            (code_gen_ptr - code_gen_buffer) / nb_tbs);
 223 #endif
 224     nb_tbs = 0;
 225     for(i = 0;i < CODE_GEN_HASH_SIZE; i++)
 226         tb_hash[i] = NULL;
 227     page_flush_tb();
 228     code_gen_ptr = code_gen_buffer;
 229     /* XXX: flush processor icache at this point */
 230 }
 231
 232 #ifdef DEBUG_TB_CHECK
 233
 234 static void tb_invalidate_check(unsigned long address)
 235 {
 236     TranslationBlock *tb;
 237     int i;
 238     address &= TARGET_PAGE_MASK;
 239     for(i = 0;i < CODE_GEN_HASH_SIZE; i++) {
 240         for(tb = tb_hash[i]; tb != NULL; tb = tb->hash_next) {
 241             if (!(address + TARGET_PAGE_SIZE <= tb->pc ||
 242                   address >= tb->pc + tb->size)) {
 243                 printf("ERROR invalidate: address=%08lx PC=%08lx size=%04x\n",
 244                        address, tb->pc, tb->size);
 245             }
 246         }
 247     }
 248 }
 249
 250 /* verify that all the pages have correct rights for code */
 251 static void tb_page_check(void)
 252 {
 253     TranslationBlock *tb;
 254     int i, flags1, flags2;
 255
 256     for(i = 0;i < CODE_GEN_HASH_SIZE; i++) {
 257         for(tb = tb_hash[i]; tb != NULL; tb = tb->hash_next) {
 258             flags1 = page_get_flags(tb->pc);
 259             flags2 = page_get_flags(tb->pc + tb->size - 1);
 260             if ((flags1 & PAGE_WRITE) || (flags2 & PAGE_WRITE)) {
 261                 printf("ERROR page flags: PC=%08lx size=%04x f1=%x f2=%x\n",
 262                        tb->pc, tb->size, flags1, flags2);
 263             }
 264         }
 265     }
 266 }
 267
 268 #endif
 269
 270 /* invalidate one TB */
 271 static inline void tb_remove(TranslationBlock **ptb, TranslationBlock *tb,
 272                              int next_offset)
 273 {
 274     TranslationBlock *tb1;
 275     for(;;) {
 276         tb1 = *ptb;
 277         if (tb1 == tb) {
 278             *ptb = *(TranslationBlock **)((char *)tb1 + next_offset);
 279             break;
 280         }
 281         ptb = (TranslationBlock **)((char *)tb1 + next_offset);
 282     }
 283 }
 284
 285 static inline void tb_invalidate(TranslationBlock *tb, int parity)
 286 {
 287     PageDesc *p;
 288     unsigned int page_index1, page_index2;
 289     unsigned int h;
 290
 291     /* remove the TB from the hash list */
 292     h = tb_hash_func(tb->pc);
 293     tb_remove(&tb_hash[h], tb,
 294               offsetof(TranslationBlock, hash_next));
 295     /* remove the TB from the page list */
 296     page_index1 = tb->pc >> TARGET_PAGE_BITS;
 297     if ((page_index1 & 1) == parity) {
 298         p = page_find(page_index1);
 299         tb_remove(&p->first_tb, tb,
 300                   offsetof(TranslationBlock, page_next[page_index1 & 1]));
 301     }
 302     page_index2 = (tb->pc + tb->size - 1) >> TARGET_PAGE_BITS;
 303     if ((page_index2 & 1) == parity) {
 304         p = page_find(page_index2);
 305         tb_remove(&p->first_tb, tb,
 306                   offsetof(TranslationBlock, page_next[page_index2 & 1]));
 307     }
 308 }
 309
 310 /* invalidate all TBs which intersect with the target page starting at addr */
 311 static void tb_invalidate_page(unsigned long address)
 312 {
 313     TranslationBlock *tb_next, *tb;
 314     unsigned int page_index;
 315     int parity1, parity2;
 316     PageDesc *p;
 317 #ifdef DEBUG_TB_INVALIDATE
 318     printf("tb_invalidate_page: %lx\n", address);
 319 #endif
 320
 321     page_index = address >> TARGET_PAGE_BITS;
 322     p = page_find(page_index);
 323     if (!p)
 324         return;
 325     tb = p->first_tb;
 326     parity1 = page_index & 1;
 327     parity2 = parity1 ^ 1;
 328     while (tb != NULL) {
 329         tb_next = tb->page_next[parity1];
 330         tb_invalidate(tb, parity2);
 331         tb = tb_next;
 332     }
 333     p->first_tb = NULL;
 334 }
 335
 336 /* add the tb in the target page and protect it if necessary */
 337 static inline void tb_alloc_page(TranslationBlock *tb, unsigned int page_index)
 338 {
 339     PageDesc *p;
 340     unsigned long host_start, host_end, addr, page_addr;
 341     int prot;
 342
 343     p = page_find_alloc(page_index);
 344     tb->page_next[page_index & 1] = p->first_tb;
 345     p->first_tb = tb;
 346     if (p->flags & PAGE_WRITE) {
 347         /* force the host page as non writable (writes will have a
 348            page fault + mprotect overhead) */
 349         page_addr = (page_index << TARGET_PAGE_BITS);
 350         host_start = page_addr & host_page_mask;
 351         host_end = host_start + host_page_size;
 352         prot = 0;
 353         for(addr = host_start; addr < host_end; addr += TARGET_PAGE_SIZE)
 354             prot |= page_get_flags(addr);
 355         mprotect((void *)host_start, host_page_size,
 356                  (prot & PAGE_BITS) & ~PAGE_WRITE);
 357 #ifdef DEBUG_TB_INVALIDATE
 358         printf("protecting code page: 0x%08lx\n",
 359                host_start);
 360 #endif
 361         p->flags &= ~PAGE_WRITE;
 362 #ifdef DEBUG_TB_CHECK
 363         tb_page_check();
 364 #endif
 365     }
 366 }
 367
 368 /* Allocate a new translation block. Flush the translation buffer if
 369    too many translation blocks or too much generated code. */
 370 TranslationBlock *tb_alloc(unsigned long pc,
 371                            unsigned long size)
 372 {
 373     TranslationBlock *tb;
 374     unsigned int page_index1, page_index2;
 375
 376     if (nb_tbs >= CODE_GEN_MAX_BLOCKS ||
 377         (code_gen_ptr - code_gen_buffer) >= CODE_GEN_BUFFER_MAX_SIZE)
 378         tb_flush();
 379     tb = &tbs[nb_tbs++];
 380     tb->pc = pc;
 381     tb->size = size;
 382
 383     /* add in the page list */
 384     page_index1 = pc >> TARGET_PAGE_BITS;
 385     tb_alloc_page(tb, page_index1);
 386     page_index2 = (pc + size - 1) >> TARGET_PAGE_BITS;
 387     if (page_index2 != page_index1) {
 388         tb_alloc_page(tb, page_index2);
 389     }
 390     return tb;
 391 }
 392
 393 /* called from signal handler: invalidate the code and unprotect the
 394    page. Return TRUE if the fault was succesfully handled. */
 395 int page_unprotect(unsigned long address)
 396 {
 397     unsigned int page_index, prot;
 398     PageDesc *p;
 399     unsigned long host_start, host_end, addr;
 400
 401     page_index = address >> TARGET_PAGE_BITS;
 402     p = page_find(page_index);
 403     if (!p)
 404         return 0;
 405     if ((p->flags & (PAGE_WRITE_ORG | PAGE_WRITE)) == PAGE_WRITE_ORG) {
 406         /* if the page was really writable, then we change its
 407            protection back to writable */
 408         host_start = address & host_page_mask;
 409         host_end = host_start + host_page_size;
 410         prot = 0;
 411         for(addr = host_start; addr < host_end; addr += TARGET_PAGE_SIZE)
 412             prot |= page_get_flags(addr);
 413         mprotect((void *)host_start, host_page_size,
 414                  (prot & PAGE_BITS) | PAGE_WRITE);
 415         p->flags |= PAGE_WRITE;
 416
 417         /* and since the content will be modified, we must invalidate
 418            the corresponding translated code. */
 419         tb_invalidate_page(address);
 420 #ifdef DEBUG_TB_CHECK
 421         tb_invalidate_check(address);
 422 #endif
 423         return 1;
 424     } else {
 425         return 0;
 426     }
 427 }
 428
 429 /* call this function when system calls directly modify a memory area */
 430 void page_unprotect_range(uint8_t *data, unsigned long data_size)
 431 {
 432     unsigned long start, end, addr;
 433
 434     start = (unsigned long)data;
 435     end = start + data_size;
 436     start &= TARGET_PAGE_MASK;
 437     end = TARGET_PAGE_ALIGN(end);
 438     for(addr = start; addr < end; addr += TARGET_PAGE_SIZE) {
 439         page_unprotect(addr);
 440     }
 441 }