1 /*-
2 * Copyright (c) 2004 Tim J. Robbins
3 * Copyright (c) 2002 Doug Rabson
4 * Copyright (c) 2000 Marcel Moolenaar
5 * Copyright (c) 1994-1995 Søren Schmidt
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer
13 * in this position and unchanged.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. The name of the author may not be used to endorse or promote products
18 * derived from this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
23 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 *
31 * $FreeBSD$
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36
37 #include <sys/capsicum.h>
38 #include <sys/file.h>
39 #include <sys/imgact.h>
40 #include <sys/ktr.h>
41 #include <sys/lock.h>
42 #include <sys/mman.h>
43 #include <sys/proc.h>
44 #include <sys/resourcevar.h>
45 #include <sys/rwlock.h>
46 #include <sys/syscallsubr.h>
47 #include <sys/sysent.h>
48 #include <sys/sysproto.h>
49
50 #include <vm/pmap.h>
51 #include <vm/vm_extern.h>
52 #include <vm/vm_map.h>
53 #include <vm/vm_object.h>
54
55 #include <compat/linux/linux_emul.h>
56 #include <compat/linux/linux_mmap.h>
57 #include <compat/linux/linux_persona.h>
58 #include <compat/linux/linux_util.h>
59
60
61 #define STACK_SIZE (2 * 1024 * 1024)
62 #define GUARD_SIZE (4 * PAGE_SIZE)
63
64 #if defined(__amd64__)
65 static void linux_fixup_prot(struct thread *td, int *prot);
66 #endif
67
68 static int
69 linux_mmap_check_fp(struct file *fp, int flags, int prot, int maxprot)
70 {
71
72 /* Linux mmap() just fails for O_WRONLY files */
73 if ((fp->f_flag & FREAD) == 0)
74 return (EACCES);
75
76 return (0);
77 }
78
79 int
80 linux_mmap_common(struct thread *td, uintptr_t addr, size_t len, int prot,
81 int flags, int fd, off_t pos)
82 {
83 struct proc *p = td->td_proc;
84 struct vmspace *vms = td->td_proc->p_vmspace;
85 int bsd_flags, error;
86 struct file *fp;
87
88 LINUX_CTR6(mmap2, "0x%lx, %ld, %ld, 0x%08lx, %ld, 0x%lx",
89 addr, len, prot, flags, fd, pos);
90
91 error = 0;
92 bsd_flags = 0;
93 fp = NULL;
94
95 /*
96 * Linux mmap(2):
97 * You must specify exactly one of MAP_SHARED and MAP_PRIVATE
98 */
99 if (!((flags & LINUX_MAP_SHARED) ^ (flags & LINUX_MAP_PRIVATE)))
100 return (EINVAL);
101
102 if (flags & LINUX_MAP_SHARED)
103 bsd_flags |= MAP_SHARED;
104 if (flags & LINUX_MAP_PRIVATE)
105 bsd_flags |= MAP_PRIVATE;
106 if (flags & LINUX_MAP_FIXED)
107 bsd_flags |= MAP_FIXED;
108 if (flags & LINUX_MAP_ANON) {
109 /* Enforce pos to be on page boundary, then ignore. */
110 if ((pos & PAGE_MASK) != 0)
111 return (EINVAL);
112 pos = 0;
113 bsd_flags |= MAP_ANON;
114 } else
115 bsd_flags |= MAP_NOSYNC;
116 if (flags & LINUX_MAP_GROWSDOWN)
117 bsd_flags |= MAP_STACK;
118
119 #if defined(__amd64__)
120 /*
121 * According to the Linux mmap(2) man page, "MAP_32BIT flag
122 * is ignored when MAP_FIXED is set."
123 */
124 if ((flags & LINUX_MAP_32BIT) && (flags & LINUX_MAP_FIXED) == 0)
125 bsd_flags |= MAP_32BIT;
126
127 /*
128 * PROT_READ, PROT_WRITE, or PROT_EXEC implies PROT_READ and PROT_EXEC
129 * on Linux/i386 if the binary requires executable stack.
130 * We do this only for IA32 emulation as on native i386 this is does not
131 * make sense without PAE.
132 *
133 * XXX. Linux checks that the file system is not mounted with noexec.
134 */
135 linux_fixup_prot(td, &prot);
136 #endif
137
138 /* Linux does not check file descriptor when MAP_ANONYMOUS is set. */
139 fd = (bsd_flags & MAP_ANON) ? -1 : fd;
140 if (flags & LINUX_MAP_GROWSDOWN) {
141 /*
142 * The Linux MAP_GROWSDOWN option does not limit auto
143 * growth of the region. Linux mmap with this option
144 * takes as addr the initial BOS, and as len, the initial
145 * region size. It can then grow down from addr without
146 * limit. However, Linux threads has an implicit internal
147 * limit to stack size of STACK_SIZE. Its just not
148 * enforced explicitly in Linux. But, here we impose
149 * a limit of (STACK_SIZE - GUARD_SIZE) on the stack
150 * region, since we can do this with our mmap.
151 *
152 * Our mmap with MAP_STACK takes addr as the maximum
153 * downsize limit on BOS, and as len the max size of
154 * the region. It then maps the top SGROWSIZ bytes,
155 * and auto grows the region down, up to the limit
156 * in addr.
157 *
158 * If we don't use the MAP_STACK option, the effect
159 * of this code is to allocate a stack region of a
160 * fixed size of (STACK_SIZE - GUARD_SIZE).
161 */
162
163 if ((caddr_t)addr + len > vms->vm_maxsaddr) {
164 /*
165 * Some Linux apps will attempt to mmap
166 * thread stacks near the top of their
167 * address space. If their TOS is greater
168 * than vm_maxsaddr, vm_map_growstack()
169 * will confuse the thread stack with the
170 * process stack and deliver a SEGV if they
171 * attempt to grow the thread stack past their
172 * current stacksize rlimit. To avoid this,
173 * adjust vm_maxsaddr upwards to reflect
174 * the current stacksize rlimit rather
175 * than the maximum possible stacksize.
176 * It would be better to adjust the
177 * mmap'ed region, but some apps do not check
178 * mmap's return value.
179 */
180 PROC_LOCK(p);
181 vms->vm_maxsaddr = (char *)p->p_sysent->sv_usrstack -
182 lim_cur_proc(p, RLIMIT_STACK);
183 PROC_UNLOCK(p);
184 }
185
186 /*
187 * This gives us our maximum stack size and a new BOS.
188 * If we're using VM_STACK, then mmap will just map
189 * the top SGROWSIZ bytes, and let the stack grow down
190 * to the limit at BOS. If we're not using VM_STACK
191 * we map the full stack, since we don't have a way
192 * to autogrow it.
193 */
194 if (len <= STACK_SIZE - GUARD_SIZE) {
195 addr = addr - (STACK_SIZE - GUARD_SIZE - len);
196 len = STACK_SIZE - GUARD_SIZE;
197 }
198 }
199
200 /*
201 * FreeBSD is free to ignore the address hint if MAP_FIXED wasn't
202 * passed. However, some Linux applications, like the ART runtime,
203 * depend on the hint. If the MAP_FIXED wasn't passed, but the
204 * address is not zero, try with MAP_FIXED and MAP_EXCL first,
205 * and fall back to the normal behaviour if that fails.
206 */
207 if (addr != 0 && (bsd_flags & MAP_FIXED) == 0 &&
208 (bsd_flags & MAP_EXCL) == 0) {
209 error = kern_mmap_fpcheck(td, addr, len, prot,
210 bsd_flags | MAP_FIXED | MAP_EXCL, fd, pos,
211 linux_mmap_check_fp);
212 if (error == 0)
213 goto out;
214 }
215
216 error = kern_mmap_fpcheck(td, addr, len, prot, bsd_flags, fd, pos,
217 linux_mmap_check_fp);
218 out:
219 LINUX_CTR2(mmap2, "return: %d (%p)", error, td->td_retval[0]);
220
221 return (error);
222 }
223
224 int
225 linux_mprotect_common(struct thread *td, uintptr_t addr, size_t len, int prot)
226 {
227
228 /* XXX Ignore PROT_GROWSDOWN and PROT_GROWSUP for now. */
229 prot &= ~(LINUX_PROT_GROWSDOWN | LINUX_PROT_GROWSUP);
230 if ((prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC)) != 0)
231 return (EINVAL);
232
233 #if defined(__amd64__)
234 linux_fixup_prot(td, &prot);
235 #endif
236 return (kern_mprotect(td, addr, len, prot));
237 }
238
239 /*
240 * Implement Linux madvise(MADV_DONTNEED), which has unusual semantics: for
241 * anonymous memory, pages in the range are immediately discarded.
242 */
243 static int
244 linux_madvise_dontneed(struct thread *td, vm_offset_t start, vm_offset_t end)
245 {
246 vm_map_t map;
247 vm_map_entry_t entry;
248 vm_object_t backing_object, object;
249 vm_offset_t estart, eend;
250 vm_pindex_t pstart, pend;
251 int error;
252
253 map = &td->td_proc->p_vmspace->vm_map;
254
255 if (!vm_map_range_valid(map, start, end))
256 return (EINVAL);
257 start = trunc_page(start);
258 end = round_page(end);
259
260 error = 0;
261 vm_map_lock_read(map);
262 if (!vm_map_lookup_entry(map, start, &entry))
263 entry = entry->next;
264 for (; entry->start < end; entry = entry->next) {
265 if ((entry->eflags & MAP_ENTRY_IS_SUB_MAP) != 0)
266 continue;
267
268 if (entry->wired_count != 0) {
269 error = EINVAL;
270 break;
271 }
272
273 object = entry->object.vm_object;
274 if (object == NULL)
275 continue;
276 if ((object->flags & (OBJ_UNMANAGED | OBJ_FICTITIOUS)) != 0)
277 continue;
278
279 pstart = OFF_TO_IDX(entry->offset);
280 if (start > entry->start) {
281 pstart += atop(start - entry->start);
282 estart = start;
283 } else {
284 estart = entry->start;
285 }
286 pend = OFF_TO_IDX(entry->offset) +
287 atop(entry->end - entry->start);
288 if (entry->end > end) {
289 pend -= atop(entry->end - end);
290 eend = end;
291 } else {
292 eend = entry->end;
293 }
294
295 if ((object->type == OBJT_DEFAULT ||
296 object->type == OBJT_SWAP) && object->handle == NULL &&
297 (object->flags & (OBJ_ONEMAPPING | OBJ_NOSPLIT)) ==
298 OBJ_ONEMAPPING) {
299 /*
300 * Singly-mapped anonymous memory is discarded. This
301 * does not match Linux's semantics when the object
302 * belongs to a shadow chain of length > 1, since
303 * subsequent faults may retrieve pages from an
304 * intermediate anonymous object. However, handling
305 * this case correctly introduces a fair bit of
306 * complexity.
307 */
308 VM_OBJECT_WLOCK(object);
309 if ((object->flags & OBJ_ONEMAPPING) != 0) {
310 vm_object_collapse(object);
311 vm_object_page_remove(object, pstart, pend, 0);
312 backing_object = object->backing_object;
313 if (backing_object != NULL &&
314 (backing_object->type == OBJT_DEFAULT ||
315 backing_object->type == OBJT_SWAP) &&
316 backing_object->handle == NULL &&
317 (backing_object->flags & OBJ_NOSPLIT) == 0)
318 linux_msg(td,
319 "possibly incorrect MADV_DONTNEED");
320 VM_OBJECT_WUNLOCK(object);
321 continue;
322 }
323 VM_OBJECT_WUNLOCK(object);
324 }
325
326 /*
327 * Handle shared mappings. Remove them outright instead of
328 * calling pmap_advise(), for consistency with Linux.
329 */
330 pmap_remove(map->pmap, estart, eend);
331 vm_object_madvise(object, pstart, pend, MADV_DONTNEED);
332 }
333 vm_map_unlock_read(map);
334
335 return (error);
336 }
337
338 int
339 linux_madvise_common(struct thread *td, uintptr_t addr, size_t len, int behav)
340 {
341
342 switch (behav) {
343 case LINUX_MADV_NORMAL:
344 return (kern_madvise(td, addr, len, MADV_NORMAL));
345 case LINUX_MADV_RANDOM:
346 return (kern_madvise(td, addr, len, MADV_RANDOM));
347 case LINUX_MADV_SEQUENTIAL:
348 return (kern_madvise(td, addr, len, MADV_SEQUENTIAL));
349 case LINUX_MADV_WILLNEED:
350 return (kern_madvise(td, addr, len, MADV_WILLNEED));
351 case LINUX_MADV_DONTNEED:
352 return (linux_madvise_dontneed(td, addr, addr + len));
353 case LINUX_MADV_FREE:
354 return (kern_madvise(td, addr, len, MADV_FREE));
355 case LINUX_MADV_REMOVE:
356 linux_msg(curthread, "unsupported madvise MADV_REMOVE");
357 return (EINVAL);
358 case LINUX_MADV_DONTFORK:
359 return (kern_minherit(td, addr, len, INHERIT_NONE));
360 case LINUX_MADV_DOFORK:
361 return (kern_minherit(td, addr, len, INHERIT_COPY));
362 case LINUX_MADV_MERGEABLE:
363 linux_msg(curthread, "unsupported madvise MADV_MERGEABLE");
364 return (EINVAL);
365 case LINUX_MADV_UNMERGEABLE:
366 /* We don't merge anyway. */
367 return (0);
368 case LINUX_MADV_HUGEPAGE:
369 /* Ignored; on FreeBSD huge pages are always on. */
370 return (0);
371 case LINUX_MADV_NOHUGEPAGE:
372 #if 0
373 /*
374 * Don't warn - Firefox uses it a lot, and in real Linux it's
375 * an optional feature.
376 */
377 linux_msg(curthread, "unsupported madvise MADV_NOHUGEPAGE");
378 #endif
379 return (EINVAL);
380 case LINUX_MADV_DONTDUMP:
381 return (kern_madvise(td, addr, len, MADV_NOCORE));
382 case LINUX_MADV_DODUMP:
383 return (kern_madvise(td, addr, len, MADV_CORE));
384 case LINUX_MADV_WIPEONFORK:
385 return (kern_minherit(td, addr, len, INHERIT_ZERO));
386 case LINUX_MADV_KEEPONFORK:
387 return (kern_minherit(td, addr, len, INHERIT_COPY));
388 case LINUX_MADV_HWPOISON:
389 linux_msg(curthread, "unsupported madvise MADV_HWPOISON");
390 return (EINVAL);
391 case LINUX_MADV_SOFT_OFFLINE:
392 linux_msg(curthread, "unsupported madvise MADV_SOFT_OFFLINE");
393 return (EINVAL);
394 default:
395 linux_msg(curthread, "unsupported madvise behav %d", behav);
396 return (EINVAL);
397 }
398 }
399
400 #if defined(__amd64__)
401 static void
402 linux_fixup_prot(struct thread *td, int *prot)
403 {
404 struct linux_pemuldata *pem;
405
406 if (SV_PROC_FLAG(td->td_proc, SV_ILP32) && *prot & PROT_READ) {
407 pem = pem_find(td->td_proc);
408 if (pem->persona & LINUX_READ_IMPLIES_EXEC)
409 *prot |= PROT_EXEC;
410 }
411
412 }
413 #endif
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