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Annotation of qemu/linux-user/mmap.c, revision 1.1

1.1     ! root        1: /*
        !             2:  *  mmap support for qemu
        !             3:  * 
        !             4:  *  Copyright (c) 2003 Fabrice Bellard
        !             5:  *
        !             6:  *  This program is free software; you can redistribute it and/or modify
        !             7:  *  it under the terms of the GNU General Public License as published by
        !             8:  *  the Free Software Foundation; either version 2 of the License, or
        !             9:  *  (at your option) any later version.
        !            10:  *
        !            11:  *  This program 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
        !            14:  *  GNU General Public License for more details.
        !            15:  *
        !            16:  *  You should have received a copy of the GNU General Public License
        !            17:  *  along with this program; if not, write to the Free Software
        !            18:  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
        !            19:  */
        !            20: #include <stdlib.h>
        !            21: #include <stdio.h>
        !            22: #include <stdarg.h>
        !            23: #include <string.h>
        !            24: #include <unistd.h>
        !            25: #include <errno.h>
        !            26: #include <sys/mman.h>
        !            27: 
        !            28: #include "qemu.h"
        !            29: 
        !            30: //#define DEBUG_MMAP
        !            31: 
        !            32: /* NOTE: all the constants are the HOST ones */
        !            33: int target_mprotect(unsigned long start, unsigned long len, int prot)
        !            34: {
        !            35:     unsigned long end, host_start, host_end, addr;
        !            36:     int prot1, ret;
        !            37: 
        !            38: #ifdef DEBUG_MMAP
        !            39:     printf("mprotect: start=0x%lx len=0x%lx prot=%c%c%c\n", start, len,
        !            40:            prot & PROT_READ ? 'r' : '-',
        !            41:            prot & PROT_WRITE ? 'w' : '-',
        !            42:            prot & PROT_EXEC ? 'x' : '-');
        !            43: #endif
        !            44: 
        !            45:     if ((start & ~TARGET_PAGE_MASK) != 0)
        !            46:         return -EINVAL;
        !            47:     len = TARGET_PAGE_ALIGN(len);
        !            48:     end = start + len;
        !            49:     if (end < start)
        !            50:         return -EINVAL;
        !            51:     if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC))
        !            52:         return -EINVAL;
        !            53:     if (len == 0)
        !            54:         return 0;
        !            55:     
        !            56:     host_start = start & qemu_host_page_mask;
        !            57:     host_end = HOST_PAGE_ALIGN(end);
        !            58:     if (start > host_start) {
        !            59:         /* handle host page containing start */
        !            60:         prot1 = prot;
        !            61:         for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) {
        !            62:             prot1 |= page_get_flags(addr);
        !            63:         }
        !            64:         if (host_end == host_start + qemu_host_page_size) {
        !            65:             for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
        !            66:                 prot1 |= page_get_flags(addr);
        !            67:             }
        !            68:             end = host_end;
        !            69:         }
        !            70:         ret = mprotect((void *)host_start, qemu_host_page_size, prot1 & PAGE_BITS);
        !            71:         if (ret != 0)
        !            72:             return ret;
        !            73:         host_start += qemu_host_page_size;
        !            74:     }
        !            75:     if (end < host_end) {
        !            76:         prot1 = prot;
        !            77:         for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
        !            78:             prot1 |= page_get_flags(addr);
        !            79:         }
        !            80:         ret = mprotect((void *)(host_end - qemu_host_page_size), qemu_host_page_size, 
        !            81:                        prot1 & PAGE_BITS);
        !            82:         if (ret != 0)
        !            83:             return ret;
        !            84:         host_end -= qemu_host_page_size;
        !            85:     }
        !            86:     
        !            87:     /* handle the pages in the middle */
        !            88:     if (host_start < host_end) {
        !            89:         ret = mprotect((void *)host_start, host_end - host_start, prot);
        !            90:         if (ret != 0)
        !            91:             return ret;
        !            92:     }
        !            93:     page_set_flags(start, start + len, prot | PAGE_VALID);
        !            94:     return 0;
        !            95: }
        !            96: 
        !            97: /* map an incomplete host page */
        !            98: int mmap_frag(unsigned long host_start, 
        !            99:                unsigned long start, unsigned long end, 
        !           100:                int prot, int flags, int fd, unsigned long offset)
        !           101: {
        !           102:     unsigned long host_end, ret, addr;
        !           103:     int prot1, prot_new;
        !           104: 
        !           105:     host_end = host_start + qemu_host_page_size;
        !           106: 
        !           107:     /* get the protection of the target pages outside the mapping */
        !           108:     prot1 = 0;
        !           109:     for(addr = host_start; addr < host_end; addr++) {
        !           110:         if (addr < start || addr >= end)
        !           111:             prot1 |= page_get_flags(addr);
        !           112:     }
        !           113:     
        !           114:     if (prot1 == 0) {
        !           115:         /* no page was there, so we allocate one */
        !           116:         ret = (long)mmap((void *)host_start, qemu_host_page_size, prot, 
        !           117:                          flags | MAP_ANONYMOUS, -1, 0);
        !           118:         if (ret == -1)
        !           119:             return ret;
        !           120:     }
        !           121:     prot1 &= PAGE_BITS;
        !           122: 
        !           123:     prot_new = prot | prot1;
        !           124:     if (!(flags & MAP_ANONYMOUS)) {
        !           125:         /* msync() won't work here, so we return an error if write is
        !           126:            possible while it is a shared mapping */
        !           127:         if ((flags & MAP_TYPE) == MAP_SHARED &&
        !           128:             (prot & PROT_WRITE))
        !           129:             return -EINVAL;
        !           130: 
        !           131:         /* adjust protection to be able to read */
        !           132:         if (!(prot1 & PROT_WRITE))
        !           133:             mprotect((void *)host_start, qemu_host_page_size, prot1 | PROT_WRITE);
        !           134:         
        !           135:         /* read the corresponding file data */
        !           136:         pread(fd, (void *)start, end - start, offset);
        !           137:         
        !           138:         /* put final protection */
        !           139:         if (prot_new != (prot1 | PROT_WRITE))
        !           140:             mprotect((void *)host_start, qemu_host_page_size, prot_new);
        !           141:     } else {
        !           142:         /* just update the protection */
        !           143:         if (prot_new != prot1) {
        !           144:             mprotect((void *)host_start, qemu_host_page_size, prot_new);
        !           145:         }
        !           146:     }
        !           147:     return 0;
        !           148: }
        !           149: 
        !           150: /* NOTE: all the constants are the HOST ones */
        !           151: long target_mmap(unsigned long start, unsigned long len, int prot, 
        !           152:                  int flags, int fd, unsigned long offset)
        !           153: {
        !           154:     unsigned long ret, end, host_start, host_end, retaddr, host_offset, host_len;
        !           155: #if defined(__alpha__) || defined(__sparc__) || defined(__x86_64__) || \
        !           156:     defined(__ia64)
        !           157:     static unsigned long last_start = 0x40000000;
        !           158: #endif
        !           159: 
        !           160: #ifdef DEBUG_MMAP
        !           161:     {
        !           162:         printf("mmap: start=0x%lx len=0x%lx prot=%c%c%c flags=",
        !           163:                start, len, 
        !           164:                prot & PROT_READ ? 'r' : '-',
        !           165:                prot & PROT_WRITE ? 'w' : '-',
        !           166:                prot & PROT_EXEC ? 'x' : '-');
        !           167:         if (flags & MAP_FIXED)
        !           168:             printf("MAP_FIXED ");
        !           169:         if (flags & MAP_ANONYMOUS)
        !           170:             printf("MAP_ANON ");
        !           171:         switch(flags & MAP_TYPE) {
        !           172:         case MAP_PRIVATE:
        !           173:             printf("MAP_PRIVATE ");
        !           174:             break;
        !           175:         case MAP_SHARED:
        !           176:             printf("MAP_SHARED ");
        !           177:             break;
        !           178:         default:
        !           179:             printf("[MAP_TYPE=0x%x] ", flags & MAP_TYPE);
        !           180:             break;
        !           181:         }
        !           182:         printf("fd=%d offset=%lx\n", fd, offset);
        !           183:     }
        !           184: #endif
        !           185: 
        !           186:     if (offset & ~TARGET_PAGE_MASK)
        !           187:         return -EINVAL;
        !           188: 
        !           189:     len = TARGET_PAGE_ALIGN(len);
        !           190:     if (len == 0)
        !           191:         return start;
        !           192:     host_start = start & qemu_host_page_mask;
        !           193: 
        !           194:     if (!(flags & MAP_FIXED)) {
        !           195: #if defined(__alpha__) || defined(__sparc__) || defined(__x86_64__) || \
        !           196:     defined(__ia64)
        !           197:         /* tell the kenel to search at the same place as i386 */
        !           198:         if (host_start == 0) {
        !           199:             host_start = last_start;
        !           200:             last_start += HOST_PAGE_ALIGN(len);
        !           201:         }
        !           202: #endif
        !           203:         if (qemu_host_page_size != qemu_real_host_page_size) {
        !           204:             /* NOTE: this code is only for debugging with '-p' option */
        !           205:             /* reserve a memory area */
        !           206:             host_len = HOST_PAGE_ALIGN(len) + qemu_host_page_size - TARGET_PAGE_SIZE;
        !           207:             host_start = (long)mmap((void *)host_start, host_len, PROT_NONE, 
        !           208:                                     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
        !           209:             if (host_start == -1)
        !           210:                 return host_start;
        !           211:             host_end = host_start + host_len;
        !           212:             start = HOST_PAGE_ALIGN(host_start);
        !           213:             end = start + HOST_PAGE_ALIGN(len);
        !           214:             if (start > host_start)
        !           215:                 munmap((void *)host_start, start - host_start);
        !           216:             if (end < host_end)
        !           217:                 munmap((void *)end, host_end - end);
        !           218:             /* use it as a fixed mapping */
        !           219:             flags |= MAP_FIXED;
        !           220:         } else {
        !           221:             /* if not fixed, no need to do anything */
        !           222:             host_offset = offset & qemu_host_page_mask;
        !           223:             host_len = len + offset - host_offset;
        !           224:             start = (long)mmap((void *)host_start, host_len, 
        !           225:                                prot, flags, fd, host_offset);
        !           226:             if (start == -1)
        !           227:                 return start;
        !           228:             /* update start so that it points to the file position at 'offset' */
        !           229:             if (!(flags & MAP_ANONYMOUS)) 
        !           230:                 start += offset - host_offset;
        !           231:             goto the_end1;
        !           232:         }
        !           233:     }
        !           234:     
        !           235:     if (start & ~TARGET_PAGE_MASK)
        !           236:         return -EINVAL;
        !           237:     end = start + len;
        !           238:     host_end = HOST_PAGE_ALIGN(end);
        !           239: 
        !           240:     /* worst case: we cannot map the file because the offset is not
        !           241:        aligned, so we read it */
        !           242:     if (!(flags & MAP_ANONYMOUS) &&
        !           243:         (offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask)) {
        !           244:         /* msync() won't work here, so we return an error if write is
        !           245:            possible while it is a shared mapping */
        !           246:         if ((flags & MAP_TYPE) == MAP_SHARED &&
        !           247:             (prot & PROT_WRITE))
        !           248:             return -EINVAL;
        !           249:         retaddr = target_mmap(start, len, prot | PROT_WRITE, 
        !           250:                               MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, 
        !           251:                               -1, 0);
        !           252:         if (retaddr == -1)
        !           253:             return retaddr;
        !           254:         pread(fd, (void *)start, len, offset);
        !           255:         if (!(prot & PROT_WRITE)) {
        !           256:             ret = target_mprotect(start, len, prot);
        !           257:             if (ret != 0)
        !           258:                 return ret;
        !           259:         }
        !           260:         goto the_end;
        !           261:     }
        !           262: 
        !           263:     /* handle the start of the mapping */
        !           264:     if (start > host_start) {
        !           265:         if (host_end == host_start + qemu_host_page_size) {
        !           266:             /* one single host page */
        !           267:             ret = mmap_frag(host_start, start, end,
        !           268:                             prot, flags, fd, offset);
        !           269:             if (ret == -1)
        !           270:                 return ret;
        !           271:             goto the_end1;
        !           272:         }
        !           273:         ret = mmap_frag(host_start, start, host_start + qemu_host_page_size,
        !           274:                         prot, flags, fd, offset);
        !           275:         if (ret == -1)
        !           276:             return ret;
        !           277:         host_start += qemu_host_page_size;
        !           278:     }
        !           279:     /* handle the end of the mapping */
        !           280:     if (end < host_end) {
        !           281:         ret = mmap_frag(host_end - qemu_host_page_size, 
        !           282:                         host_end - qemu_host_page_size, host_end,
        !           283:                         prot, flags, fd, 
        !           284:                         offset + host_end - qemu_host_page_size - start);
        !           285:         if (ret == -1)
        !           286:             return ret;
        !           287:         host_end -= qemu_host_page_size;
        !           288:     }
        !           289:     
        !           290:     /* map the middle (easier) */
        !           291:     if (host_start < host_end) {
        !           292:         unsigned long offset1;
        !           293:        if (flags & MAP_ANONYMOUS)
        !           294:          offset1 = 0;
        !           295:        else
        !           296:          offset1 = offset + host_start - start;
        !           297:         ret = (long)mmap((void *)host_start, host_end - host_start, 
        !           298:                          prot, flags, fd, offset1);
        !           299:         if (ret == -1)
        !           300:             return ret;
        !           301:     }
        !           302:  the_end1:
        !           303:     page_set_flags(start, start + len, prot | PAGE_VALID);
        !           304:  the_end:
        !           305: #ifdef DEBUG_MMAP
        !           306:     printf("ret=0x%lx\n", (long)start);
        !           307:     page_dump(stdout);
        !           308:     printf("\n");
        !           309: #endif
        !           310:     return start;
        !           311: }
        !           312: 
        !           313: int target_munmap(unsigned long start, unsigned long len)
        !           314: {
        !           315:     unsigned long end, host_start, host_end, addr;
        !           316:     int prot, ret;
        !           317: 
        !           318: #ifdef DEBUG_MMAP
        !           319:     printf("munmap: start=0x%lx len=0x%lx\n", start, len);
        !           320: #endif
        !           321:     if (start & ~TARGET_PAGE_MASK)
        !           322:         return -EINVAL;
        !           323:     len = TARGET_PAGE_ALIGN(len);
        !           324:     if (len == 0)
        !           325:         return -EINVAL;
        !           326:     end = start + len;
        !           327:     host_start = start & qemu_host_page_mask;
        !           328:     host_end = HOST_PAGE_ALIGN(end);
        !           329: 
        !           330:     if (start > host_start) {
        !           331:         /* handle host page containing start */
        !           332:         prot = 0;
        !           333:         for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) {
        !           334:             prot |= page_get_flags(addr);
        !           335:         }
        !           336:         if (host_end == host_start + qemu_host_page_size) {
        !           337:             for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
        !           338:                 prot |= page_get_flags(addr);
        !           339:             }
        !           340:             end = host_end;
        !           341:         }
        !           342:         if (prot != 0)
        !           343:             host_start += qemu_host_page_size;
        !           344:     }
        !           345:     if (end < host_end) {
        !           346:         prot = 0;
        !           347:         for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
        !           348:             prot |= page_get_flags(addr);
        !           349:         }
        !           350:         if (prot != 0)
        !           351:             host_end -= qemu_host_page_size;
        !           352:     }
        !           353:     
        !           354:     /* unmap what we can */
        !           355:     if (host_start < host_end) {
        !           356:         ret = munmap((void *)host_start, host_end - host_start);
        !           357:         if (ret != 0)
        !           358:             return ret;
        !           359:     }
        !           360: 
        !           361:     page_set_flags(start, start + len, 0);
        !           362:     return 0;
        !           363: }
        !           364: 
        !           365: /* XXX: currently, we only handle MAP_ANONYMOUS and not MAP_FIXED
        !           366:    blocks which have been allocated starting on a host page */
        !           367: long target_mremap(unsigned long old_addr, unsigned long old_size, 
        !           368:                    unsigned long new_size, unsigned long flags,
        !           369:                    unsigned long new_addr)
        !           370: {
        !           371:     int prot;
        !           372: 
        !           373:     /* XXX: use 5 args syscall */
        !           374:     new_addr = (long)mremap((void *)old_addr, old_size, new_size, flags);
        !           375:     if (new_addr == -1)
        !           376:         return new_addr;
        !           377:     prot = page_get_flags(old_addr);
        !           378:     page_set_flags(old_addr, old_addr + old_size, 0);
        !           379:     page_set_flags(new_addr, new_addr + new_size, prot | PAGE_VALID);
        !           380:     return new_addr;
        !           381: }
        !           382: 
        !           383: int target_msync(unsigned long start, unsigned long len, int flags)
        !           384: {
        !           385:     unsigned long end;
        !           386: 
        !           387:     if (start & ~TARGET_PAGE_MASK)
        !           388:         return -EINVAL;
        !           389:     len = TARGET_PAGE_ALIGN(len);
        !           390:     end = start + len;
        !           391:     if (end < start)
        !           392:         return -EINVAL;
        !           393:     if (end == start)
        !           394:         return 0;
        !           395:     
        !           396:     start &= qemu_host_page_mask;
        !           397:     return msync((void *)start, end - start, flags);
        !           398: }
        !           399: 

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