Merge remote-tracking branch 'remotes/philmd/tags/mips-20210413' into staging
[qemu.git] / bsd-user / mmap.c
1 /*
2 * mmap support for qemu
3 *
4 * Copyright (c) 2003 - 2008 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, see <http://www.gnu.org/licenses/>.
18 */
19 #include "qemu/osdep.h"
20
21 #include "qemu.h"
22 #include "qemu-common.h"
23 #include "bsd-mman.h"
24 #include "exec/exec-all.h"
25
26 //#define DEBUG_MMAP
27
28 static pthread_mutex_t mmap_mutex = PTHREAD_MUTEX_INITIALIZER;
29 static __thread int mmap_lock_count;
30
31 void mmap_lock(void)
32 {
33 if (mmap_lock_count++ == 0) {
34 pthread_mutex_lock(&mmap_mutex);
35 }
36 }
37
38 void mmap_unlock(void)
39 {
40 if (--mmap_lock_count == 0) {
41 pthread_mutex_unlock(&mmap_mutex);
42 }
43 }
44
45 bool have_mmap_lock(void)
46 {
47 return mmap_lock_count > 0 ? true : false;
48 }
49
50 /* Grab lock to make sure things are in a consistent state after fork(). */
51 void mmap_fork_start(void)
52 {
53 if (mmap_lock_count)
54 abort();
55 pthread_mutex_lock(&mmap_mutex);
56 }
57
58 void mmap_fork_end(int child)
59 {
60 if (child)
61 pthread_mutex_init(&mmap_mutex, NULL);
62 else
63 pthread_mutex_unlock(&mmap_mutex);
64 }
65
66 /* NOTE: all the constants are the HOST ones, but addresses are target. */
67 int target_mprotect(abi_ulong start, abi_ulong len, int prot)
68 {
69 abi_ulong end, host_start, host_end, addr;
70 int prot1, ret;
71
72 #ifdef DEBUG_MMAP
73 printf("mprotect: start=0x" TARGET_FMT_lx
74 " len=0x" TARGET_FMT_lx " prot=%c%c%c\n", start, len,
75 prot & PROT_READ ? 'r' : '-',
76 prot & PROT_WRITE ? 'w' : '-',
77 prot & PROT_EXEC ? 'x' : '-');
78 #endif
79
80 if ((start & ~TARGET_PAGE_MASK) != 0)
81 return -EINVAL;
82 len = TARGET_PAGE_ALIGN(len);
83 end = start + len;
84 if (end < start)
85 return -EINVAL;
86 prot &= PROT_READ | PROT_WRITE | PROT_EXEC;
87 if (len == 0)
88 return 0;
89
90 mmap_lock();
91 host_start = start & qemu_host_page_mask;
92 host_end = HOST_PAGE_ALIGN(end);
93 if (start > host_start) {
94 /* handle host page containing start */
95 prot1 = prot;
96 for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) {
97 prot1 |= page_get_flags(addr);
98 }
99 if (host_end == host_start + qemu_host_page_size) {
100 for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
101 prot1 |= page_get_flags(addr);
102 }
103 end = host_end;
104 }
105 ret = mprotect(g2h_untagged(host_start),
106 qemu_host_page_size, prot1 & PAGE_BITS);
107 if (ret != 0)
108 goto error;
109 host_start += qemu_host_page_size;
110 }
111 if (end < host_end) {
112 prot1 = prot;
113 for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) {
114 prot1 |= page_get_flags(addr);
115 }
116 ret = mprotect(g2h_untagged(host_end - qemu_host_page_size),
117 qemu_host_page_size, prot1 & PAGE_BITS);
118 if (ret != 0)
119 goto error;
120 host_end -= qemu_host_page_size;
121 }
122
123 /* handle the pages in the middle */
124 if (host_start < host_end) {
125 ret = mprotect(g2h_untagged(host_start), host_end - host_start, prot);
126 if (ret != 0)
127 goto error;
128 }
129 page_set_flags(start, start + len, prot | PAGE_VALID);
130 mmap_unlock();
131 return 0;
132 error:
133 mmap_unlock();
134 return ret;
135 }
136
137 /* map an incomplete host page */
138 static int mmap_frag(abi_ulong real_start,
139 abi_ulong start, abi_ulong end,
140 int prot, int flags, int fd, abi_ulong offset)
141 {
142 abi_ulong real_end, addr;
143 void *host_start;
144 int prot1, prot_new;
145
146 real_end = real_start + qemu_host_page_size;
147 host_start = g2h_untagged(real_start);
148
149 /* get the protection of the target pages outside the mapping */
150 prot1 = 0;
151 for(addr = real_start; addr < real_end; addr++) {
152 if (addr < start || addr >= end)
153 prot1 |= page_get_flags(addr);
154 }
155
156 if (prot1 == 0) {
157 /* no page was there, so we allocate one */
158 void *p = mmap(host_start, qemu_host_page_size, prot,
159 flags | MAP_ANON, -1, 0);
160 if (p == MAP_FAILED)
161 return -1;
162 prot1 = prot;
163 }
164 prot1 &= PAGE_BITS;
165
166 prot_new = prot | prot1;
167 if (!(flags & MAP_ANON)) {
168 /* msync() won't work here, so we return an error if write is
169 possible while it is a shared mapping */
170 if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED &&
171 (prot & PROT_WRITE))
172 return -1;
173
174 /* adjust protection to be able to read */
175 if (!(prot1 & PROT_WRITE))
176 mprotect(host_start, qemu_host_page_size, prot1 | PROT_WRITE);
177
178 /* read the corresponding file data */
179 pread(fd, g2h_untagged(start), end - start, offset);
180
181 /* put final protection */
182 if (prot_new != (prot1 | PROT_WRITE))
183 mprotect(host_start, qemu_host_page_size, prot_new);
184 } else {
185 /* just update the protection */
186 if (prot_new != prot1) {
187 mprotect(host_start, qemu_host_page_size, prot_new);
188 }
189 }
190 return 0;
191 }
192
193 static abi_ulong mmap_next_start = 0x40000000;
194
195 unsigned long last_brk;
196
197 /* find a free memory area of size 'size'. The search starts at
198 'start'. If 'start' == 0, then a default start address is used.
199 Return -1 if error.
200 */
201 /* page_init() marks pages used by the host as reserved to be sure not
202 to use them. */
203 static abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size)
204 {
205 abi_ulong addr, addr1, addr_start;
206 int prot;
207 unsigned long new_brk;
208
209 new_brk = (unsigned long)sbrk(0);
210 if (last_brk && last_brk < new_brk && last_brk == (target_ulong)last_brk) {
211 /* This is a hack to catch the host allocating memory with brk().
212 If it uses mmap then we loose.
213 FIXME: We really want to avoid the host allocating memory in
214 the first place, and maybe leave some slack to avoid switching
215 to mmap. */
216 page_set_flags(last_brk & TARGET_PAGE_MASK,
217 TARGET_PAGE_ALIGN(new_brk),
218 PAGE_RESERVED);
219 }
220 last_brk = new_brk;
221
222 size = HOST_PAGE_ALIGN(size);
223 start = start & qemu_host_page_mask;
224 addr = start;
225 if (addr == 0)
226 addr = mmap_next_start;
227 addr_start = addr;
228 for(;;) {
229 prot = 0;
230 for(addr1 = addr; addr1 < (addr + size); addr1 += TARGET_PAGE_SIZE) {
231 prot |= page_get_flags(addr1);
232 }
233 if (prot == 0)
234 break;
235 addr += qemu_host_page_size;
236 /* we found nothing */
237 if (addr == addr_start)
238 return (abi_ulong)-1;
239 }
240 if (start == 0)
241 mmap_next_start = addr + size;
242 return addr;
243 }
244
245 /* NOTE: all the constants are the HOST ones */
246 abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
247 int flags, int fd, abi_ulong offset)
248 {
249 abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len;
250 unsigned long host_start;
251
252 mmap_lock();
253 #ifdef DEBUG_MMAP
254 {
255 printf("mmap: start=0x" TARGET_FMT_lx
256 " len=0x" TARGET_FMT_lx " prot=%c%c%c flags=",
257 start, len,
258 prot & PROT_READ ? 'r' : '-',
259 prot & PROT_WRITE ? 'w' : '-',
260 prot & PROT_EXEC ? 'x' : '-');
261 if (flags & MAP_FIXED)
262 printf("MAP_FIXED ");
263 if (flags & MAP_ANON)
264 printf("MAP_ANON ");
265 switch(flags & TARGET_BSD_MAP_FLAGMASK) {
266 case MAP_PRIVATE:
267 printf("MAP_PRIVATE ");
268 break;
269 case MAP_SHARED:
270 printf("MAP_SHARED ");
271 break;
272 default:
273 printf("[MAP_FLAGMASK=0x%x] ", flags & TARGET_BSD_MAP_FLAGMASK);
274 break;
275 }
276 printf("fd=%d offset=" TARGET_FMT_lx "\n", fd, offset);
277 }
278 #endif
279
280 if (offset & ~TARGET_PAGE_MASK) {
281 errno = EINVAL;
282 goto fail;
283 }
284
285 len = TARGET_PAGE_ALIGN(len);
286 if (len == 0)
287 goto the_end;
288 real_start = start & qemu_host_page_mask;
289
290 if (!(flags & MAP_FIXED)) {
291 abi_ulong mmap_start;
292 void *p;
293 host_offset = offset & qemu_host_page_mask;
294 host_len = len + offset - host_offset;
295 host_len = HOST_PAGE_ALIGN(host_len);
296 mmap_start = mmap_find_vma(real_start, host_len);
297 if (mmap_start == (abi_ulong)-1) {
298 errno = ENOMEM;
299 goto fail;
300 }
301 /* Note: we prefer to control the mapping address. It is
302 especially important if qemu_host_page_size >
303 qemu_real_host_page_size */
304 p = mmap(g2h_untagged(mmap_start),
305 host_len, prot, flags | MAP_FIXED, fd, host_offset);
306 if (p == MAP_FAILED)
307 goto fail;
308 /* update start so that it points to the file position at 'offset' */
309 host_start = (unsigned long)p;
310 if (!(flags & MAP_ANON))
311 host_start += offset - host_offset;
312 start = h2g(host_start);
313 } else {
314 int flg;
315 target_ulong addr;
316
317 if (start & ~TARGET_PAGE_MASK) {
318 errno = EINVAL;
319 goto fail;
320 }
321 end = start + len;
322 real_end = HOST_PAGE_ALIGN(end);
323
324 for(addr = real_start; addr < real_end; addr += TARGET_PAGE_SIZE) {
325 flg = page_get_flags(addr);
326 if (flg & PAGE_RESERVED) {
327 errno = ENXIO;
328 goto fail;
329 }
330 }
331
332 /* worst case: we cannot map the file because the offset is not
333 aligned, so we read it */
334 if (!(flags & MAP_ANON) &&
335 (offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask)) {
336 /* msync() won't work here, so we return an error if write is
337 possible while it is a shared mapping */
338 if ((flags & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED &&
339 (prot & PROT_WRITE)) {
340 errno = EINVAL;
341 goto fail;
342 }
343 retaddr = target_mmap(start, len, prot | PROT_WRITE,
344 MAP_FIXED | MAP_PRIVATE | MAP_ANON,
345 -1, 0);
346 if (retaddr == -1)
347 goto fail;
348 pread(fd, g2h_untagged(start), len, offset);
349 if (!(prot & PROT_WRITE)) {
350 ret = target_mprotect(start, len, prot);
351 if (ret != 0) {
352 start = ret;
353 goto the_end;
354 }
355 }
356 goto the_end;
357 }
358
359 /* handle the start of the mapping */
360 if (start > real_start) {
361 if (real_end == real_start + qemu_host_page_size) {
362 /* one single host page */
363 ret = mmap_frag(real_start, start, end,
364 prot, flags, fd, offset);
365 if (ret == -1)
366 goto fail;
367 goto the_end1;
368 }
369 ret = mmap_frag(real_start, start, real_start + qemu_host_page_size,
370 prot, flags, fd, offset);
371 if (ret == -1)
372 goto fail;
373 real_start += qemu_host_page_size;
374 }
375 /* handle the end of the mapping */
376 if (end < real_end) {
377 ret = mmap_frag(real_end - qemu_host_page_size,
378 real_end - qemu_host_page_size, real_end,
379 prot, flags, fd,
380 offset + real_end - qemu_host_page_size - start);
381 if (ret == -1)
382 goto fail;
383 real_end -= qemu_host_page_size;
384 }
385
386 /* map the middle (easier) */
387 if (real_start < real_end) {
388 void *p;
389 unsigned long offset1;
390 if (flags & MAP_ANON)
391 offset1 = 0;
392 else
393 offset1 = offset + real_start - start;
394 p = mmap(g2h_untagged(real_start), real_end - real_start,
395 prot, flags, fd, offset1);
396 if (p == MAP_FAILED)
397 goto fail;
398 }
399 }
400 the_end1:
401 page_set_flags(start, start + len, prot | PAGE_VALID);
402 the_end:
403 #ifdef DEBUG_MMAP
404 printf("ret=0x" TARGET_FMT_lx "\n", start);
405 page_dump(stdout);
406 printf("\n");
407 #endif
408 mmap_unlock();
409 return start;
410 fail:
411 mmap_unlock();
412 return -1;
413 }
414
415 int target_munmap(abi_ulong start, abi_ulong len)
416 {
417 abi_ulong end, real_start, real_end, addr;
418 int prot, ret;
419
420 #ifdef DEBUG_MMAP
421 printf("munmap: start=0x%lx len=0x%lx\n", start, len);
422 #endif
423 if (start & ~TARGET_PAGE_MASK)
424 return -EINVAL;
425 len = TARGET_PAGE_ALIGN(len);
426 if (len == 0)
427 return -EINVAL;
428 mmap_lock();
429 end = start + len;
430 real_start = start & qemu_host_page_mask;
431 real_end = HOST_PAGE_ALIGN(end);
432
433 if (start > real_start) {
434 /* handle host page containing start */
435 prot = 0;
436 for(addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) {
437 prot |= page_get_flags(addr);
438 }
439 if (real_end == real_start + qemu_host_page_size) {
440 for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) {
441 prot |= page_get_flags(addr);
442 }
443 end = real_end;
444 }
445 if (prot != 0)
446 real_start += qemu_host_page_size;
447 }
448 if (end < real_end) {
449 prot = 0;
450 for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) {
451 prot |= page_get_flags(addr);
452 }
453 if (prot != 0)
454 real_end -= qemu_host_page_size;
455 }
456
457 ret = 0;
458 /* unmap what we can */
459 if (real_start < real_end) {
460 ret = munmap(g2h_untagged(real_start), real_end - real_start);
461 }
462
463 if (ret == 0)
464 page_set_flags(start, start + len, 0);
465 mmap_unlock();
466 return ret;
467 }
468
469 int target_msync(abi_ulong start, abi_ulong len, int flags)
470 {
471 abi_ulong end;
472
473 if (start & ~TARGET_PAGE_MASK)
474 return -EINVAL;
475 len = TARGET_PAGE_ALIGN(len);
476 end = start + len;
477 if (end < start)
478 return -EINVAL;
479 if (end == start)
480 return 0;
481
482 start &= qemu_host_page_mask;
483 return msync(g2h_untagged(start), end - start, flags);
484 }