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1da177e4 LT |
1 | /* |
2 | * linux/kernel/fork.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * 'fork.c' contains the help-routines for the 'fork' system call | |
9 | * (see also entry.S and others). | |
10 | * Fork is rather simple, once you get the hang of it, but the memory | |
11 | * management can be a bitch. See 'mm/memory.c': 'copy_page_range()' | |
12 | */ | |
13 | ||
14 | #include <linux/config.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/init.h> | |
17 | #include <linux/unistd.h> | |
18 | #include <linux/smp_lock.h> | |
19 | #include <linux/module.h> | |
20 | #include <linux/vmalloc.h> | |
21 | #include <linux/completion.h> | |
22 | #include <linux/namespace.h> | |
23 | #include <linux/personality.h> | |
24 | #include <linux/mempolicy.h> | |
25 | #include <linux/sem.h> | |
26 | #include <linux/file.h> | |
27 | #include <linux/key.h> | |
28 | #include <linux/binfmts.h> | |
29 | #include <linux/mman.h> | |
30 | #include <linux/fs.h> | |
31 | #include <linux/cpu.h> | |
32 | #include <linux/cpuset.h> | |
33 | #include <linux/security.h> | |
34 | #include <linux/swap.h> | |
35 | #include <linux/syscalls.h> | |
36 | #include <linux/jiffies.h> | |
37 | #include <linux/futex.h> | |
38 | #include <linux/ptrace.h> | |
39 | #include <linux/mount.h> | |
40 | #include <linux/audit.h> | |
41 | #include <linux/profile.h> | |
42 | #include <linux/rmap.h> | |
43 | #include <linux/acct.h> | |
44 | ||
45 | #include <asm/pgtable.h> | |
46 | #include <asm/pgalloc.h> | |
47 | #include <asm/uaccess.h> | |
48 | #include <asm/mmu_context.h> | |
49 | #include <asm/cacheflush.h> | |
50 | #include <asm/tlbflush.h> | |
51 | ||
52 | /* | |
53 | * Protected counters by write_lock_irq(&tasklist_lock) | |
54 | */ | |
55 | unsigned long total_forks; /* Handle normal Linux uptimes. */ | |
56 | int nr_threads; /* The idle threads do not count.. */ | |
57 | ||
58 | int max_threads; /* tunable limit on nr_threads */ | |
59 | ||
60 | DEFINE_PER_CPU(unsigned long, process_counts) = 0; | |
61 | ||
62 | __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ | |
63 | ||
64 | EXPORT_SYMBOL(tasklist_lock); | |
65 | ||
66 | int nr_processes(void) | |
67 | { | |
68 | int cpu; | |
69 | int total = 0; | |
70 | ||
71 | for_each_online_cpu(cpu) | |
72 | total += per_cpu(process_counts, cpu); | |
73 | ||
74 | return total; | |
75 | } | |
76 | ||
77 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR | |
78 | # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL) | |
79 | # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk)) | |
80 | static kmem_cache_t *task_struct_cachep; | |
81 | #endif | |
82 | ||
83 | /* SLAB cache for signal_struct structures (tsk->signal) */ | |
84 | kmem_cache_t *signal_cachep; | |
85 | ||
86 | /* SLAB cache for sighand_struct structures (tsk->sighand) */ | |
87 | kmem_cache_t *sighand_cachep; | |
88 | ||
89 | /* SLAB cache for files_struct structures (tsk->files) */ | |
90 | kmem_cache_t *files_cachep; | |
91 | ||
92 | /* SLAB cache for fs_struct structures (tsk->fs) */ | |
93 | kmem_cache_t *fs_cachep; | |
94 | ||
95 | /* SLAB cache for vm_area_struct structures */ | |
96 | kmem_cache_t *vm_area_cachep; | |
97 | ||
98 | /* SLAB cache for mm_struct structures (tsk->mm) */ | |
99 | static kmem_cache_t *mm_cachep; | |
100 | ||
101 | void free_task(struct task_struct *tsk) | |
102 | { | |
103 | free_thread_info(tsk->thread_info); | |
104 | free_task_struct(tsk); | |
105 | } | |
106 | EXPORT_SYMBOL(free_task); | |
107 | ||
108 | void __put_task_struct(struct task_struct *tsk) | |
109 | { | |
110 | WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE))); | |
111 | WARN_ON(atomic_read(&tsk->usage)); | |
112 | WARN_ON(tsk == current); | |
113 | ||
114 | if (unlikely(tsk->audit_context)) | |
115 | audit_free(tsk); | |
116 | security_task_free(tsk); | |
117 | free_uid(tsk->user); | |
118 | put_group_info(tsk->group_info); | |
119 | ||
120 | if (!profile_handoff_task(tsk)) | |
121 | free_task(tsk); | |
122 | } | |
123 | ||
124 | void __init fork_init(unsigned long mempages) | |
125 | { | |
126 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR | |
127 | #ifndef ARCH_MIN_TASKALIGN | |
128 | #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES | |
129 | #endif | |
130 | /* create a slab on which task_structs can be allocated */ | |
131 | task_struct_cachep = | |
132 | kmem_cache_create("task_struct", sizeof(struct task_struct), | |
133 | ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL); | |
134 | #endif | |
135 | ||
136 | /* | |
137 | * The default maximum number of threads is set to a safe | |
138 | * value: the thread structures can take up at most half | |
139 | * of memory. | |
140 | */ | |
141 | max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); | |
142 | ||
143 | /* | |
144 | * we need to allow at least 20 threads to boot a system | |
145 | */ | |
146 | if(max_threads < 20) | |
147 | max_threads = 20; | |
148 | ||
149 | init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; | |
150 | init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; | |
151 | init_task.signal->rlim[RLIMIT_SIGPENDING] = | |
152 | init_task.signal->rlim[RLIMIT_NPROC]; | |
153 | } | |
154 | ||
155 | static struct task_struct *dup_task_struct(struct task_struct *orig) | |
156 | { | |
157 | struct task_struct *tsk; | |
158 | struct thread_info *ti; | |
159 | ||
160 | prepare_to_copy(orig); | |
161 | ||
162 | tsk = alloc_task_struct(); | |
163 | if (!tsk) | |
164 | return NULL; | |
165 | ||
166 | ti = alloc_thread_info(tsk); | |
167 | if (!ti) { | |
168 | free_task_struct(tsk); | |
169 | return NULL; | |
170 | } | |
171 | ||
172 | *ti = *orig->thread_info; | |
173 | *tsk = *orig; | |
174 | tsk->thread_info = ti; | |
175 | ti->task = tsk; | |
176 | ||
177 | /* One for us, one for whoever does the "release_task()" (usually parent) */ | |
178 | atomic_set(&tsk->usage,2); | |
179 | return tsk; | |
180 | } | |
181 | ||
182 | #ifdef CONFIG_MMU | |
183 | static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm) | |
184 | { | |
185 | struct vm_area_struct * mpnt, *tmp, **pprev; | |
186 | struct rb_node **rb_link, *rb_parent; | |
187 | int retval; | |
188 | unsigned long charge; | |
189 | struct mempolicy *pol; | |
190 | ||
191 | down_write(&oldmm->mmap_sem); | |
192 | flush_cache_mm(current->mm); | |
193 | mm->locked_vm = 0; | |
194 | mm->mmap = NULL; | |
195 | mm->mmap_cache = NULL; | |
196 | mm->free_area_cache = oldmm->mmap_base; | |
1363c3cd | 197 | mm->cached_hole_size = ~0UL; |
1da177e4 LT |
198 | mm->map_count = 0; |
199 | set_mm_counter(mm, rss, 0); | |
200 | set_mm_counter(mm, anon_rss, 0); | |
201 | cpus_clear(mm->cpu_vm_mask); | |
202 | mm->mm_rb = RB_ROOT; | |
203 | rb_link = &mm->mm_rb.rb_node; | |
204 | rb_parent = NULL; | |
205 | pprev = &mm->mmap; | |
206 | ||
207 | for (mpnt = current->mm->mmap ; mpnt ; mpnt = mpnt->vm_next) { | |
208 | struct file *file; | |
209 | ||
210 | if (mpnt->vm_flags & VM_DONTCOPY) { | |
211 | __vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, | |
212 | -vma_pages(mpnt)); | |
213 | continue; | |
214 | } | |
215 | charge = 0; | |
216 | if (mpnt->vm_flags & VM_ACCOUNT) { | |
217 | unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; | |
218 | if (security_vm_enough_memory(len)) | |
219 | goto fail_nomem; | |
220 | charge = len; | |
221 | } | |
222 | tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); | |
223 | if (!tmp) | |
224 | goto fail_nomem; | |
225 | *tmp = *mpnt; | |
226 | pol = mpol_copy(vma_policy(mpnt)); | |
227 | retval = PTR_ERR(pol); | |
228 | if (IS_ERR(pol)) | |
229 | goto fail_nomem_policy; | |
230 | vma_set_policy(tmp, pol); | |
231 | tmp->vm_flags &= ~VM_LOCKED; | |
232 | tmp->vm_mm = mm; | |
233 | tmp->vm_next = NULL; | |
234 | anon_vma_link(tmp); | |
235 | file = tmp->vm_file; | |
236 | if (file) { | |
237 | struct inode *inode = file->f_dentry->d_inode; | |
238 | get_file(file); | |
239 | if (tmp->vm_flags & VM_DENYWRITE) | |
240 | atomic_dec(&inode->i_writecount); | |
241 | ||
242 | /* insert tmp into the share list, just after mpnt */ | |
243 | spin_lock(&file->f_mapping->i_mmap_lock); | |
244 | tmp->vm_truncate_count = mpnt->vm_truncate_count; | |
245 | flush_dcache_mmap_lock(file->f_mapping); | |
246 | vma_prio_tree_add(tmp, mpnt); | |
247 | flush_dcache_mmap_unlock(file->f_mapping); | |
248 | spin_unlock(&file->f_mapping->i_mmap_lock); | |
249 | } | |
250 | ||
251 | /* | |
252 | * Link in the new vma and copy the page table entries: | |
253 | * link in first so that swapoff can see swap entries, | |
254 | * and try_to_unmap_one's find_vma find the new vma. | |
255 | */ | |
256 | spin_lock(&mm->page_table_lock); | |
257 | *pprev = tmp; | |
258 | pprev = &tmp->vm_next; | |
259 | ||
260 | __vma_link_rb(mm, tmp, rb_link, rb_parent); | |
261 | rb_link = &tmp->vm_rb.rb_right; | |
262 | rb_parent = &tmp->vm_rb; | |
263 | ||
264 | mm->map_count++; | |
265 | retval = copy_page_range(mm, current->mm, tmp); | |
266 | spin_unlock(&mm->page_table_lock); | |
267 | ||
268 | if (tmp->vm_ops && tmp->vm_ops->open) | |
269 | tmp->vm_ops->open(tmp); | |
270 | ||
271 | if (retval) | |
272 | goto out; | |
273 | } | |
274 | retval = 0; | |
275 | ||
276 | out: | |
277 | flush_tlb_mm(current->mm); | |
278 | up_write(&oldmm->mmap_sem); | |
279 | return retval; | |
280 | fail_nomem_policy: | |
281 | kmem_cache_free(vm_area_cachep, tmp); | |
282 | fail_nomem: | |
283 | retval = -ENOMEM; | |
284 | vm_unacct_memory(charge); | |
285 | goto out; | |
286 | } | |
287 | ||
288 | static inline int mm_alloc_pgd(struct mm_struct * mm) | |
289 | { | |
290 | mm->pgd = pgd_alloc(mm); | |
291 | if (unlikely(!mm->pgd)) | |
292 | return -ENOMEM; | |
293 | return 0; | |
294 | } | |
295 | ||
296 | static inline void mm_free_pgd(struct mm_struct * mm) | |
297 | { | |
298 | pgd_free(mm->pgd); | |
299 | } | |
300 | #else | |
301 | #define dup_mmap(mm, oldmm) (0) | |
302 | #define mm_alloc_pgd(mm) (0) | |
303 | #define mm_free_pgd(mm) | |
304 | #endif /* CONFIG_MMU */ | |
305 | ||
306 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); | |
307 | ||
308 | #define allocate_mm() (kmem_cache_alloc(mm_cachep, SLAB_KERNEL)) | |
309 | #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) | |
310 | ||
311 | #include <linux/init_task.h> | |
312 | ||
313 | static struct mm_struct * mm_init(struct mm_struct * mm) | |
314 | { | |
315 | atomic_set(&mm->mm_users, 1); | |
316 | atomic_set(&mm->mm_count, 1); | |
317 | init_rwsem(&mm->mmap_sem); | |
318 | INIT_LIST_HEAD(&mm->mmlist); | |
319 | mm->core_waiters = 0; | |
320 | mm->nr_ptes = 0; | |
321 | spin_lock_init(&mm->page_table_lock); | |
322 | rwlock_init(&mm->ioctx_list_lock); | |
323 | mm->ioctx_list = NULL; | |
324 | mm->default_kioctx = (struct kioctx)INIT_KIOCTX(mm->default_kioctx, *mm); | |
325 | mm->free_area_cache = TASK_UNMAPPED_BASE; | |
1363c3cd | 326 | mm->cached_hole_size = ~0UL; |
1da177e4 LT |
327 | |
328 | if (likely(!mm_alloc_pgd(mm))) { | |
329 | mm->def_flags = 0; | |
330 | return mm; | |
331 | } | |
332 | free_mm(mm); | |
333 | return NULL; | |
334 | } | |
335 | ||
336 | /* | |
337 | * Allocate and initialize an mm_struct. | |
338 | */ | |
339 | struct mm_struct * mm_alloc(void) | |
340 | { | |
341 | struct mm_struct * mm; | |
342 | ||
343 | mm = allocate_mm(); | |
344 | if (mm) { | |
345 | memset(mm, 0, sizeof(*mm)); | |
346 | mm = mm_init(mm); | |
347 | } | |
348 | return mm; | |
349 | } | |
350 | ||
351 | /* | |
352 | * Called when the last reference to the mm | |
353 | * is dropped: either by a lazy thread or by | |
354 | * mmput. Free the page directory and the mm. | |
355 | */ | |
356 | void fastcall __mmdrop(struct mm_struct *mm) | |
357 | { | |
358 | BUG_ON(mm == &init_mm); | |
359 | mm_free_pgd(mm); | |
360 | destroy_context(mm); | |
361 | free_mm(mm); | |
362 | } | |
363 | ||
364 | /* | |
365 | * Decrement the use count and release all resources for an mm. | |
366 | */ | |
367 | void mmput(struct mm_struct *mm) | |
368 | { | |
369 | if (atomic_dec_and_test(&mm->mm_users)) { | |
370 | exit_aio(mm); | |
371 | exit_mmap(mm); | |
372 | if (!list_empty(&mm->mmlist)) { | |
373 | spin_lock(&mmlist_lock); | |
374 | list_del(&mm->mmlist); | |
375 | spin_unlock(&mmlist_lock); | |
376 | } | |
377 | put_swap_token(mm); | |
378 | mmdrop(mm); | |
379 | } | |
380 | } | |
381 | EXPORT_SYMBOL_GPL(mmput); | |
382 | ||
383 | /** | |
384 | * get_task_mm - acquire a reference to the task's mm | |
385 | * | |
386 | * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning | |
387 | * this kernel workthread has transiently adopted a user mm with use_mm, | |
388 | * to do its AIO) is not set and if so returns a reference to it, after | |
389 | * bumping up the use count. User must release the mm via mmput() | |
390 | * after use. Typically used by /proc and ptrace. | |
391 | */ | |
392 | struct mm_struct *get_task_mm(struct task_struct *task) | |
393 | { | |
394 | struct mm_struct *mm; | |
395 | ||
396 | task_lock(task); | |
397 | mm = task->mm; | |
398 | if (mm) { | |
399 | if (task->flags & PF_BORROWED_MM) | |
400 | mm = NULL; | |
401 | else | |
402 | atomic_inc(&mm->mm_users); | |
403 | } | |
404 | task_unlock(task); | |
405 | return mm; | |
406 | } | |
407 | EXPORT_SYMBOL_GPL(get_task_mm); | |
408 | ||
409 | /* Please note the differences between mmput and mm_release. | |
410 | * mmput is called whenever we stop holding onto a mm_struct, | |
411 | * error success whatever. | |
412 | * | |
413 | * mm_release is called after a mm_struct has been removed | |
414 | * from the current process. | |
415 | * | |
416 | * This difference is important for error handling, when we | |
417 | * only half set up a mm_struct for a new process and need to restore | |
418 | * the old one. Because we mmput the new mm_struct before | |
419 | * restoring the old one. . . | |
420 | * Eric Biederman 10 January 1998 | |
421 | */ | |
422 | void mm_release(struct task_struct *tsk, struct mm_struct *mm) | |
423 | { | |
424 | struct completion *vfork_done = tsk->vfork_done; | |
425 | ||
426 | /* Get rid of any cached register state */ | |
427 | deactivate_mm(tsk, mm); | |
428 | ||
429 | /* notify parent sleeping on vfork() */ | |
430 | if (vfork_done) { | |
431 | tsk->vfork_done = NULL; | |
432 | complete(vfork_done); | |
433 | } | |
434 | if (tsk->clear_child_tid && atomic_read(&mm->mm_users) > 1) { | |
435 | u32 __user * tidptr = tsk->clear_child_tid; | |
436 | tsk->clear_child_tid = NULL; | |
437 | ||
438 | /* | |
439 | * We don't check the error code - if userspace has | |
440 | * not set up a proper pointer then tough luck. | |
441 | */ | |
442 | put_user(0, tidptr); | |
443 | sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0); | |
444 | } | |
445 | } | |
446 | ||
447 | static int copy_mm(unsigned long clone_flags, struct task_struct * tsk) | |
448 | { | |
449 | struct mm_struct * mm, *oldmm; | |
450 | int retval; | |
451 | ||
452 | tsk->min_flt = tsk->maj_flt = 0; | |
453 | tsk->nvcsw = tsk->nivcsw = 0; | |
454 | ||
455 | tsk->mm = NULL; | |
456 | tsk->active_mm = NULL; | |
457 | ||
458 | /* | |
459 | * Are we cloning a kernel thread? | |
460 | * | |
461 | * We need to steal a active VM for that.. | |
462 | */ | |
463 | oldmm = current->mm; | |
464 | if (!oldmm) | |
465 | return 0; | |
466 | ||
467 | if (clone_flags & CLONE_VM) { | |
468 | atomic_inc(&oldmm->mm_users); | |
469 | mm = oldmm; | |
470 | /* | |
471 | * There are cases where the PTL is held to ensure no | |
472 | * new threads start up in user mode using an mm, which | |
473 | * allows optimizing out ipis; the tlb_gather_mmu code | |
474 | * is an example. | |
475 | */ | |
476 | spin_unlock_wait(&oldmm->page_table_lock); | |
477 | goto good_mm; | |
478 | } | |
479 | ||
480 | retval = -ENOMEM; | |
481 | mm = allocate_mm(); | |
482 | if (!mm) | |
483 | goto fail_nomem; | |
484 | ||
485 | /* Copy the current MM stuff.. */ | |
486 | memcpy(mm, oldmm, sizeof(*mm)); | |
487 | if (!mm_init(mm)) | |
488 | goto fail_nomem; | |
489 | ||
490 | if (init_new_context(tsk,mm)) | |
491 | goto fail_nocontext; | |
492 | ||
493 | retval = dup_mmap(mm, oldmm); | |
494 | if (retval) | |
495 | goto free_pt; | |
496 | ||
497 | mm->hiwater_rss = get_mm_counter(mm,rss); | |
498 | mm->hiwater_vm = mm->total_vm; | |
499 | ||
500 | good_mm: | |
501 | tsk->mm = mm; | |
502 | tsk->active_mm = mm; | |
503 | return 0; | |
504 | ||
505 | free_pt: | |
506 | mmput(mm); | |
507 | fail_nomem: | |
508 | return retval; | |
509 | ||
510 | fail_nocontext: | |
511 | /* | |
512 | * If init_new_context() failed, we cannot use mmput() to free the mm | |
513 | * because it calls destroy_context() | |
514 | */ | |
515 | mm_free_pgd(mm); | |
516 | free_mm(mm); | |
517 | return retval; | |
518 | } | |
519 | ||
520 | static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old) | |
521 | { | |
522 | struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL); | |
523 | /* We don't need to lock fs - think why ;-) */ | |
524 | if (fs) { | |
525 | atomic_set(&fs->count, 1); | |
526 | rwlock_init(&fs->lock); | |
527 | fs->umask = old->umask; | |
528 | read_lock(&old->lock); | |
529 | fs->rootmnt = mntget(old->rootmnt); | |
530 | fs->root = dget(old->root); | |
531 | fs->pwdmnt = mntget(old->pwdmnt); | |
532 | fs->pwd = dget(old->pwd); | |
533 | if (old->altroot) { | |
534 | fs->altrootmnt = mntget(old->altrootmnt); | |
535 | fs->altroot = dget(old->altroot); | |
536 | } else { | |
537 | fs->altrootmnt = NULL; | |
538 | fs->altroot = NULL; | |
539 | } | |
540 | read_unlock(&old->lock); | |
541 | } | |
542 | return fs; | |
543 | } | |
544 | ||
545 | struct fs_struct *copy_fs_struct(struct fs_struct *old) | |
546 | { | |
547 | return __copy_fs_struct(old); | |
548 | } | |
549 | ||
550 | EXPORT_SYMBOL_GPL(copy_fs_struct); | |
551 | ||
552 | static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk) | |
553 | { | |
554 | if (clone_flags & CLONE_FS) { | |
555 | atomic_inc(¤t->fs->count); | |
556 | return 0; | |
557 | } | |
558 | tsk->fs = __copy_fs_struct(current->fs); | |
559 | if (!tsk->fs) | |
560 | return -ENOMEM; | |
561 | return 0; | |
562 | } | |
563 | ||
564 | static int count_open_files(struct files_struct *files, int size) | |
565 | { | |
566 | int i; | |
567 | ||
568 | /* Find the last open fd */ | |
569 | for (i = size/(8*sizeof(long)); i > 0; ) { | |
570 | if (files->open_fds->fds_bits[--i]) | |
571 | break; | |
572 | } | |
573 | i = (i+1) * 8 * sizeof(long); | |
574 | return i; | |
575 | } | |
576 | ||
577 | static int copy_files(unsigned long clone_flags, struct task_struct * tsk) | |
578 | { | |
579 | struct files_struct *oldf, *newf; | |
580 | struct file **old_fds, **new_fds; | |
581 | int open_files, size, i, error = 0, expand; | |
582 | ||
583 | /* | |
584 | * A background process may not have any files ... | |
585 | */ | |
586 | oldf = current->files; | |
587 | if (!oldf) | |
588 | goto out; | |
589 | ||
590 | if (clone_flags & CLONE_FILES) { | |
591 | atomic_inc(&oldf->count); | |
592 | goto out; | |
593 | } | |
594 | ||
595 | /* | |
596 | * Note: we may be using current for both targets (See exec.c) | |
597 | * This works because we cache current->files (old) as oldf. Don't | |
598 | * break this. | |
599 | */ | |
600 | tsk->files = NULL; | |
601 | error = -ENOMEM; | |
602 | newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL); | |
603 | if (!newf) | |
604 | goto out; | |
605 | ||
606 | atomic_set(&newf->count, 1); | |
607 | ||
608 | spin_lock_init(&newf->file_lock); | |
609 | newf->next_fd = 0; | |
610 | newf->max_fds = NR_OPEN_DEFAULT; | |
611 | newf->max_fdset = __FD_SETSIZE; | |
612 | newf->close_on_exec = &newf->close_on_exec_init; | |
613 | newf->open_fds = &newf->open_fds_init; | |
614 | newf->fd = &newf->fd_array[0]; | |
615 | ||
616 | spin_lock(&oldf->file_lock); | |
617 | ||
618 | open_files = count_open_files(oldf, oldf->max_fdset); | |
619 | expand = 0; | |
620 | ||
621 | /* | |
622 | * Check whether we need to allocate a larger fd array or fd set. | |
623 | * Note: we're not a clone task, so the open count won't change. | |
624 | */ | |
625 | if (open_files > newf->max_fdset) { | |
626 | newf->max_fdset = 0; | |
627 | expand = 1; | |
628 | } | |
629 | if (open_files > newf->max_fds) { | |
630 | newf->max_fds = 0; | |
631 | expand = 1; | |
632 | } | |
633 | ||
634 | /* if the old fdset gets grown now, we'll only copy up to "size" fds */ | |
635 | if (expand) { | |
636 | spin_unlock(&oldf->file_lock); | |
637 | spin_lock(&newf->file_lock); | |
638 | error = expand_files(newf, open_files-1); | |
639 | spin_unlock(&newf->file_lock); | |
640 | if (error < 0) | |
641 | goto out_release; | |
642 | spin_lock(&oldf->file_lock); | |
643 | } | |
644 | ||
645 | old_fds = oldf->fd; | |
646 | new_fds = newf->fd; | |
647 | ||
648 | memcpy(newf->open_fds->fds_bits, oldf->open_fds->fds_bits, open_files/8); | |
649 | memcpy(newf->close_on_exec->fds_bits, oldf->close_on_exec->fds_bits, open_files/8); | |
650 | ||
651 | for (i = open_files; i != 0; i--) { | |
652 | struct file *f = *old_fds++; | |
653 | if (f) { | |
654 | get_file(f); | |
655 | } else { | |
656 | /* | |
657 | * The fd may be claimed in the fd bitmap but not yet | |
658 | * instantiated in the files array if a sibling thread | |
659 | * is partway through open(). So make sure that this | |
660 | * fd is available to the new process. | |
661 | */ | |
662 | FD_CLR(open_files - i, newf->open_fds); | |
663 | } | |
664 | *new_fds++ = f; | |
665 | } | |
666 | spin_unlock(&oldf->file_lock); | |
667 | ||
668 | /* compute the remainder to be cleared */ | |
669 | size = (newf->max_fds - open_files) * sizeof(struct file *); | |
670 | ||
671 | /* This is long word aligned thus could use a optimized version */ | |
672 | memset(new_fds, 0, size); | |
673 | ||
674 | if (newf->max_fdset > open_files) { | |
675 | int left = (newf->max_fdset-open_files)/8; | |
676 | int start = open_files / (8 * sizeof(unsigned long)); | |
677 | ||
678 | memset(&newf->open_fds->fds_bits[start], 0, left); | |
679 | memset(&newf->close_on_exec->fds_bits[start], 0, left); | |
680 | } | |
681 | ||
682 | tsk->files = newf; | |
683 | error = 0; | |
684 | out: | |
685 | return error; | |
686 | ||
687 | out_release: | |
688 | free_fdset (newf->close_on_exec, newf->max_fdset); | |
689 | free_fdset (newf->open_fds, newf->max_fdset); | |
690 | free_fd_array(newf->fd, newf->max_fds); | |
691 | kmem_cache_free(files_cachep, newf); | |
692 | goto out; | |
693 | } | |
694 | ||
695 | /* | |
696 | * Helper to unshare the files of the current task. | |
697 | * We don't want to expose copy_files internals to | |
698 | * the exec layer of the kernel. | |
699 | */ | |
700 | ||
701 | int unshare_files(void) | |
702 | { | |
703 | struct files_struct *files = current->files; | |
704 | int rc; | |
705 | ||
706 | if(!files) | |
707 | BUG(); | |
708 | ||
709 | /* This can race but the race causes us to copy when we don't | |
710 | need to and drop the copy */ | |
711 | if(atomic_read(&files->count) == 1) | |
712 | { | |
713 | atomic_inc(&files->count); | |
714 | return 0; | |
715 | } | |
716 | rc = copy_files(0, current); | |
717 | if(rc) | |
718 | current->files = files; | |
719 | return rc; | |
720 | } | |
721 | ||
722 | EXPORT_SYMBOL(unshare_files); | |
723 | ||
724 | static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk) | |
725 | { | |
726 | struct sighand_struct *sig; | |
727 | ||
728 | if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) { | |
729 | atomic_inc(¤t->sighand->count); | |
730 | return 0; | |
731 | } | |
732 | sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); | |
733 | tsk->sighand = sig; | |
734 | if (!sig) | |
735 | return -ENOMEM; | |
736 | spin_lock_init(&sig->siglock); | |
737 | atomic_set(&sig->count, 1); | |
738 | memcpy(sig->action, current->sighand->action, sizeof(sig->action)); | |
739 | return 0; | |
740 | } | |
741 | ||
742 | static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk) | |
743 | { | |
744 | struct signal_struct *sig; | |
745 | int ret; | |
746 | ||
747 | if (clone_flags & CLONE_THREAD) { | |
748 | atomic_inc(¤t->signal->count); | |
749 | atomic_inc(¤t->signal->live); | |
750 | return 0; | |
751 | } | |
752 | sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL); | |
753 | tsk->signal = sig; | |
754 | if (!sig) | |
755 | return -ENOMEM; | |
756 | ||
757 | ret = copy_thread_group_keys(tsk); | |
758 | if (ret < 0) { | |
759 | kmem_cache_free(signal_cachep, sig); | |
760 | return ret; | |
761 | } | |
762 | ||
763 | atomic_set(&sig->count, 1); | |
764 | atomic_set(&sig->live, 1); | |
765 | init_waitqueue_head(&sig->wait_chldexit); | |
766 | sig->flags = 0; | |
767 | sig->group_exit_code = 0; | |
768 | sig->group_exit_task = NULL; | |
769 | sig->group_stop_count = 0; | |
770 | sig->curr_target = NULL; | |
771 | init_sigpending(&sig->shared_pending); | |
772 | INIT_LIST_HEAD(&sig->posix_timers); | |
773 | ||
774 | sig->it_real_value = sig->it_real_incr = 0; | |
775 | sig->real_timer.function = it_real_fn; | |
776 | sig->real_timer.data = (unsigned long) tsk; | |
777 | init_timer(&sig->real_timer); | |
778 | ||
779 | sig->it_virt_expires = cputime_zero; | |
780 | sig->it_virt_incr = cputime_zero; | |
781 | sig->it_prof_expires = cputime_zero; | |
782 | sig->it_prof_incr = cputime_zero; | |
783 | ||
784 | sig->tty = current->signal->tty; | |
785 | sig->pgrp = process_group(current); | |
786 | sig->session = current->signal->session; | |
787 | sig->leader = 0; /* session leadership doesn't inherit */ | |
788 | sig->tty_old_pgrp = 0; | |
789 | ||
790 | sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero; | |
791 | sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0; | |
792 | sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0; | |
793 | sig->sched_time = 0; | |
794 | INIT_LIST_HEAD(&sig->cpu_timers[0]); | |
795 | INIT_LIST_HEAD(&sig->cpu_timers[1]); | |
796 | INIT_LIST_HEAD(&sig->cpu_timers[2]); | |
797 | ||
798 | task_lock(current->group_leader); | |
799 | memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); | |
800 | task_unlock(current->group_leader); | |
801 | ||
802 | if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) { | |
803 | /* | |
804 | * New sole thread in the process gets an expiry time | |
805 | * of the whole CPU time limit. | |
806 | */ | |
807 | tsk->it_prof_expires = | |
808 | secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur); | |
809 | } | |
810 | ||
811 | return 0; | |
812 | } | |
813 | ||
814 | static inline void copy_flags(unsigned long clone_flags, struct task_struct *p) | |
815 | { | |
816 | unsigned long new_flags = p->flags; | |
817 | ||
818 | new_flags &= ~PF_SUPERPRIV; | |
819 | new_flags |= PF_FORKNOEXEC; | |
820 | if (!(clone_flags & CLONE_PTRACE)) | |
821 | p->ptrace = 0; | |
822 | p->flags = new_flags; | |
823 | } | |
824 | ||
825 | asmlinkage long sys_set_tid_address(int __user *tidptr) | |
826 | { | |
827 | current->clear_child_tid = tidptr; | |
828 | ||
829 | return current->pid; | |
830 | } | |
831 | ||
832 | /* | |
833 | * This creates a new process as a copy of the old one, | |
834 | * but does not actually start it yet. | |
835 | * | |
836 | * It copies the registers, and all the appropriate | |
837 | * parts of the process environment (as per the clone | |
838 | * flags). The actual kick-off is left to the caller. | |
839 | */ | |
840 | static task_t *copy_process(unsigned long clone_flags, | |
841 | unsigned long stack_start, | |
842 | struct pt_regs *regs, | |
843 | unsigned long stack_size, | |
844 | int __user *parent_tidptr, | |
845 | int __user *child_tidptr, | |
846 | int pid) | |
847 | { | |
848 | int retval; | |
849 | struct task_struct *p = NULL; | |
850 | ||
851 | if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) | |
852 | return ERR_PTR(-EINVAL); | |
853 | ||
854 | /* | |
855 | * Thread groups must share signals as well, and detached threads | |
856 | * can only be started up within the thread group. | |
857 | */ | |
858 | if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) | |
859 | return ERR_PTR(-EINVAL); | |
860 | ||
861 | /* | |
862 | * Shared signal handlers imply shared VM. By way of the above, | |
863 | * thread groups also imply shared VM. Blocking this case allows | |
864 | * for various simplifications in other code. | |
865 | */ | |
866 | if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) | |
867 | return ERR_PTR(-EINVAL); | |
868 | ||
869 | retval = security_task_create(clone_flags); | |
870 | if (retval) | |
871 | goto fork_out; | |
872 | ||
873 | retval = -ENOMEM; | |
874 | p = dup_task_struct(current); | |
875 | if (!p) | |
876 | goto fork_out; | |
877 | ||
878 | retval = -EAGAIN; | |
879 | if (atomic_read(&p->user->processes) >= | |
880 | p->signal->rlim[RLIMIT_NPROC].rlim_cur) { | |
881 | if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) && | |
882 | p->user != &root_user) | |
883 | goto bad_fork_free; | |
884 | } | |
885 | ||
886 | atomic_inc(&p->user->__count); | |
887 | atomic_inc(&p->user->processes); | |
888 | get_group_info(p->group_info); | |
889 | ||
890 | /* | |
891 | * If multiple threads are within copy_process(), then this check | |
892 | * triggers too late. This doesn't hurt, the check is only there | |
893 | * to stop root fork bombs. | |
894 | */ | |
895 | if (nr_threads >= max_threads) | |
896 | goto bad_fork_cleanup_count; | |
897 | ||
898 | if (!try_module_get(p->thread_info->exec_domain->module)) | |
899 | goto bad_fork_cleanup_count; | |
900 | ||
901 | if (p->binfmt && !try_module_get(p->binfmt->module)) | |
902 | goto bad_fork_cleanup_put_domain; | |
903 | ||
904 | p->did_exec = 0; | |
905 | copy_flags(clone_flags, p); | |
906 | p->pid = pid; | |
907 | retval = -EFAULT; | |
908 | if (clone_flags & CLONE_PARENT_SETTID) | |
909 | if (put_user(p->pid, parent_tidptr)) | |
910 | goto bad_fork_cleanup; | |
911 | ||
912 | p->proc_dentry = NULL; | |
913 | ||
914 | INIT_LIST_HEAD(&p->children); | |
915 | INIT_LIST_HEAD(&p->sibling); | |
916 | p->vfork_done = NULL; | |
917 | spin_lock_init(&p->alloc_lock); | |
918 | spin_lock_init(&p->proc_lock); | |
919 | ||
920 | clear_tsk_thread_flag(p, TIF_SIGPENDING); | |
921 | init_sigpending(&p->pending); | |
922 | ||
923 | p->utime = cputime_zero; | |
924 | p->stime = cputime_zero; | |
925 | p->sched_time = 0; | |
926 | p->rchar = 0; /* I/O counter: bytes read */ | |
927 | p->wchar = 0; /* I/O counter: bytes written */ | |
928 | p->syscr = 0; /* I/O counter: read syscalls */ | |
929 | p->syscw = 0; /* I/O counter: write syscalls */ | |
930 | acct_clear_integrals(p); | |
931 | ||
932 | p->it_virt_expires = cputime_zero; | |
933 | p->it_prof_expires = cputime_zero; | |
934 | p->it_sched_expires = 0; | |
935 | INIT_LIST_HEAD(&p->cpu_timers[0]); | |
936 | INIT_LIST_HEAD(&p->cpu_timers[1]); | |
937 | INIT_LIST_HEAD(&p->cpu_timers[2]); | |
938 | ||
939 | p->lock_depth = -1; /* -1 = no lock */ | |
940 | do_posix_clock_monotonic_gettime(&p->start_time); | |
941 | p->security = NULL; | |
942 | p->io_context = NULL; | |
943 | p->io_wait = NULL; | |
944 | p->audit_context = NULL; | |
945 | #ifdef CONFIG_NUMA | |
946 | p->mempolicy = mpol_copy(p->mempolicy); | |
947 | if (IS_ERR(p->mempolicy)) { | |
948 | retval = PTR_ERR(p->mempolicy); | |
949 | p->mempolicy = NULL; | |
950 | goto bad_fork_cleanup; | |
951 | } | |
952 | #endif | |
953 | ||
954 | p->tgid = p->pid; | |
955 | if (clone_flags & CLONE_THREAD) | |
956 | p->tgid = current->tgid; | |
957 | ||
958 | if ((retval = security_task_alloc(p))) | |
959 | goto bad_fork_cleanup_policy; | |
960 | if ((retval = audit_alloc(p))) | |
961 | goto bad_fork_cleanup_security; | |
962 | /* copy all the process information */ | |
963 | if ((retval = copy_semundo(clone_flags, p))) | |
964 | goto bad_fork_cleanup_audit; | |
965 | if ((retval = copy_files(clone_flags, p))) | |
966 | goto bad_fork_cleanup_semundo; | |
967 | if ((retval = copy_fs(clone_flags, p))) | |
968 | goto bad_fork_cleanup_files; | |
969 | if ((retval = copy_sighand(clone_flags, p))) | |
970 | goto bad_fork_cleanup_fs; | |
971 | if ((retval = copy_signal(clone_flags, p))) | |
972 | goto bad_fork_cleanup_sighand; | |
973 | if ((retval = copy_mm(clone_flags, p))) | |
974 | goto bad_fork_cleanup_signal; | |
975 | if ((retval = copy_keys(clone_flags, p))) | |
976 | goto bad_fork_cleanup_mm; | |
977 | if ((retval = copy_namespace(clone_flags, p))) | |
978 | goto bad_fork_cleanup_keys; | |
979 | retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs); | |
980 | if (retval) | |
981 | goto bad_fork_cleanup_namespace; | |
982 | ||
983 | p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; | |
984 | /* | |
985 | * Clear TID on mm_release()? | |
986 | */ | |
987 | p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL; | |
988 | ||
989 | /* | |
990 | * Syscall tracing should be turned off in the child regardless | |
991 | * of CLONE_PTRACE. | |
992 | */ | |
993 | clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); | |
994 | ||
995 | /* Our parent execution domain becomes current domain | |
996 | These must match for thread signalling to apply */ | |
997 | ||
998 | p->parent_exec_id = p->self_exec_id; | |
999 | ||
1000 | /* ok, now we should be set up.. */ | |
1001 | p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL); | |
1002 | p->pdeath_signal = 0; | |
1003 | p->exit_state = 0; | |
1004 | ||
1005 | /* Perform scheduler related setup */ | |
1006 | sched_fork(p); | |
1007 | ||
1008 | /* | |
1009 | * Ok, make it visible to the rest of the system. | |
1010 | * We dont wake it up yet. | |
1011 | */ | |
1012 | p->group_leader = p; | |
1013 | INIT_LIST_HEAD(&p->ptrace_children); | |
1014 | INIT_LIST_HEAD(&p->ptrace_list); | |
1015 | ||
1016 | /* Need tasklist lock for parent etc handling! */ | |
1017 | write_lock_irq(&tasklist_lock); | |
1018 | ||
1019 | /* | |
1020 | * The task hasn't been attached yet, so cpus_allowed mask cannot | |
1021 | * have changed. The cpus_allowed mask of the parent may have | |
1022 | * changed after it was copied first time, and it may then move to | |
1023 | * another CPU - so we re-copy it here and set the child's CPU to | |
1024 | * the parent's CPU. This avoids alot of nasty races. | |
1025 | */ | |
1026 | p->cpus_allowed = current->cpus_allowed; | |
1027 | set_task_cpu(p, smp_processor_id()); | |
1028 | ||
1029 | /* | |
1030 | * Check for pending SIGKILL! The new thread should not be allowed | |
1031 | * to slip out of an OOM kill. (or normal SIGKILL.) | |
1032 | */ | |
1033 | if (sigismember(¤t->pending.signal, SIGKILL)) { | |
1034 | write_unlock_irq(&tasklist_lock); | |
1035 | retval = -EINTR; | |
1036 | goto bad_fork_cleanup_namespace; | |
1037 | } | |
1038 | ||
1039 | /* CLONE_PARENT re-uses the old parent */ | |
1040 | if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) | |
1041 | p->real_parent = current->real_parent; | |
1042 | else | |
1043 | p->real_parent = current; | |
1044 | p->parent = p->real_parent; | |
1045 | ||
1046 | if (clone_flags & CLONE_THREAD) { | |
1047 | spin_lock(¤t->sighand->siglock); | |
1048 | /* | |
1049 | * Important: if an exit-all has been started then | |
1050 | * do not create this new thread - the whole thread | |
1051 | * group is supposed to exit anyway. | |
1052 | */ | |
1053 | if (current->signal->flags & SIGNAL_GROUP_EXIT) { | |
1054 | spin_unlock(¤t->sighand->siglock); | |
1055 | write_unlock_irq(&tasklist_lock); | |
1056 | retval = -EAGAIN; | |
1057 | goto bad_fork_cleanup_namespace; | |
1058 | } | |
1059 | p->group_leader = current->group_leader; | |
1060 | ||
1061 | if (current->signal->group_stop_count > 0) { | |
1062 | /* | |
1063 | * There is an all-stop in progress for the group. | |
1064 | * We ourselves will stop as soon as we check signals. | |
1065 | * Make the new thread part of that group stop too. | |
1066 | */ | |
1067 | current->signal->group_stop_count++; | |
1068 | set_tsk_thread_flag(p, TIF_SIGPENDING); | |
1069 | } | |
1070 | ||
1071 | if (!cputime_eq(current->signal->it_virt_expires, | |
1072 | cputime_zero) || | |
1073 | !cputime_eq(current->signal->it_prof_expires, | |
1074 | cputime_zero) || | |
1075 | current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY || | |
1076 | !list_empty(¤t->signal->cpu_timers[0]) || | |
1077 | !list_empty(¤t->signal->cpu_timers[1]) || | |
1078 | !list_empty(¤t->signal->cpu_timers[2])) { | |
1079 | /* | |
1080 | * Have child wake up on its first tick to check | |
1081 | * for process CPU timers. | |
1082 | */ | |
1083 | p->it_prof_expires = jiffies_to_cputime(1); | |
1084 | } | |
1085 | ||
1086 | spin_unlock(¤t->sighand->siglock); | |
1087 | } | |
1088 | ||
1089 | SET_LINKS(p); | |
1090 | if (unlikely(p->ptrace & PT_PTRACED)) | |
1091 | __ptrace_link(p, current->parent); | |
1092 | ||
1093 | cpuset_fork(p); | |
1094 | ||
1095 | attach_pid(p, PIDTYPE_PID, p->pid); | |
1096 | attach_pid(p, PIDTYPE_TGID, p->tgid); | |
1097 | if (thread_group_leader(p)) { | |
1098 | attach_pid(p, PIDTYPE_PGID, process_group(p)); | |
1099 | attach_pid(p, PIDTYPE_SID, p->signal->session); | |
1100 | if (p->pid) | |
1101 | __get_cpu_var(process_counts)++; | |
1102 | } | |
1103 | ||
1104 | nr_threads++; | |
1105 | total_forks++; | |
1106 | write_unlock_irq(&tasklist_lock); | |
1107 | retval = 0; | |
1108 | ||
1109 | fork_out: | |
1110 | if (retval) | |
1111 | return ERR_PTR(retval); | |
1112 | return p; | |
1113 | ||
1114 | bad_fork_cleanup_namespace: | |
1115 | exit_namespace(p); | |
1116 | bad_fork_cleanup_keys: | |
1117 | exit_keys(p); | |
1118 | bad_fork_cleanup_mm: | |
1119 | if (p->mm) | |
1120 | mmput(p->mm); | |
1121 | bad_fork_cleanup_signal: | |
1122 | exit_signal(p); | |
1123 | bad_fork_cleanup_sighand: | |
1124 | exit_sighand(p); | |
1125 | bad_fork_cleanup_fs: | |
1126 | exit_fs(p); /* blocking */ | |
1127 | bad_fork_cleanup_files: | |
1128 | exit_files(p); /* blocking */ | |
1129 | bad_fork_cleanup_semundo: | |
1130 | exit_sem(p); | |
1131 | bad_fork_cleanup_audit: | |
1132 | audit_free(p); | |
1133 | bad_fork_cleanup_security: | |
1134 | security_task_free(p); | |
1135 | bad_fork_cleanup_policy: | |
1136 | #ifdef CONFIG_NUMA | |
1137 | mpol_free(p->mempolicy); | |
1138 | #endif | |
1139 | bad_fork_cleanup: | |
1140 | if (p->binfmt) | |
1141 | module_put(p->binfmt->module); | |
1142 | bad_fork_cleanup_put_domain: | |
1143 | module_put(p->thread_info->exec_domain->module); | |
1144 | bad_fork_cleanup_count: | |
1145 | put_group_info(p->group_info); | |
1146 | atomic_dec(&p->user->processes); | |
1147 | free_uid(p->user); | |
1148 | bad_fork_free: | |
1149 | free_task(p); | |
1150 | goto fork_out; | |
1151 | } | |
1152 | ||
1153 | struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs) | |
1154 | { | |
1155 | memset(regs, 0, sizeof(struct pt_regs)); | |
1156 | return regs; | |
1157 | } | |
1158 | ||
1159 | task_t * __devinit fork_idle(int cpu) | |
1160 | { | |
1161 | task_t *task; | |
1162 | struct pt_regs regs; | |
1163 | ||
1164 | task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, NULL, 0); | |
1165 | if (!task) | |
1166 | return ERR_PTR(-ENOMEM); | |
1167 | init_idle(task, cpu); | |
1168 | unhash_process(task); | |
1169 | return task; | |
1170 | } | |
1171 | ||
1172 | static inline int fork_traceflag (unsigned clone_flags) | |
1173 | { | |
1174 | if (clone_flags & CLONE_UNTRACED) | |
1175 | return 0; | |
1176 | else if (clone_flags & CLONE_VFORK) { | |
1177 | if (current->ptrace & PT_TRACE_VFORK) | |
1178 | return PTRACE_EVENT_VFORK; | |
1179 | } else if ((clone_flags & CSIGNAL) != SIGCHLD) { | |
1180 | if (current->ptrace & PT_TRACE_CLONE) | |
1181 | return PTRACE_EVENT_CLONE; | |
1182 | } else if (current->ptrace & PT_TRACE_FORK) | |
1183 | return PTRACE_EVENT_FORK; | |
1184 | ||
1185 | return 0; | |
1186 | } | |
1187 | ||
1188 | /* | |
1189 | * Ok, this is the main fork-routine. | |
1190 | * | |
1191 | * It copies the process, and if successful kick-starts | |
1192 | * it and waits for it to finish using the VM if required. | |
1193 | */ | |
1194 | long do_fork(unsigned long clone_flags, | |
1195 | unsigned long stack_start, | |
1196 | struct pt_regs *regs, | |
1197 | unsigned long stack_size, | |
1198 | int __user *parent_tidptr, | |
1199 | int __user *child_tidptr) | |
1200 | { | |
1201 | struct task_struct *p; | |
1202 | int trace = 0; | |
1203 | long pid = alloc_pidmap(); | |
1204 | ||
1205 | if (pid < 0) | |
1206 | return -EAGAIN; | |
1207 | if (unlikely(current->ptrace)) { | |
1208 | trace = fork_traceflag (clone_flags); | |
1209 | if (trace) | |
1210 | clone_flags |= CLONE_PTRACE; | |
1211 | } | |
1212 | ||
1213 | p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, pid); | |
1214 | /* | |
1215 | * Do this prior waking up the new thread - the thread pointer | |
1216 | * might get invalid after that point, if the thread exits quickly. | |
1217 | */ | |
1218 | if (!IS_ERR(p)) { | |
1219 | struct completion vfork; | |
1220 | ||
1221 | if (clone_flags & CLONE_VFORK) { | |
1222 | p->vfork_done = &vfork; | |
1223 | init_completion(&vfork); | |
1224 | } | |
1225 | ||
1226 | if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) { | |
1227 | /* | |
1228 | * We'll start up with an immediate SIGSTOP. | |
1229 | */ | |
1230 | sigaddset(&p->pending.signal, SIGSTOP); | |
1231 | set_tsk_thread_flag(p, TIF_SIGPENDING); | |
1232 | } | |
1233 | ||
1234 | if (!(clone_flags & CLONE_STOPPED)) | |
1235 | wake_up_new_task(p, clone_flags); | |
1236 | else | |
1237 | p->state = TASK_STOPPED; | |
1238 | ||
1239 | if (unlikely (trace)) { | |
1240 | current->ptrace_message = pid; | |
1241 | ptrace_notify ((trace << 8) | SIGTRAP); | |
1242 | } | |
1243 | ||
1244 | if (clone_flags & CLONE_VFORK) { | |
1245 | wait_for_completion(&vfork); | |
1246 | if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE)) | |
1247 | ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP); | |
1248 | } | |
1249 | } else { | |
1250 | free_pidmap(pid); | |
1251 | pid = PTR_ERR(p); | |
1252 | } | |
1253 | return pid; | |
1254 | } | |
1255 | ||
1256 | void __init proc_caches_init(void) | |
1257 | { | |
1258 | sighand_cachep = kmem_cache_create("sighand_cache", | |
1259 | sizeof(struct sighand_struct), 0, | |
1260 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); | |
1261 | signal_cachep = kmem_cache_create("signal_cache", | |
1262 | sizeof(struct signal_struct), 0, | |
1263 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); | |
1264 | files_cachep = kmem_cache_create("files_cache", | |
1265 | sizeof(struct files_struct), 0, | |
1266 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); | |
1267 | fs_cachep = kmem_cache_create("fs_cache", | |
1268 | sizeof(struct fs_struct), 0, | |
1269 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); | |
1270 | vm_area_cachep = kmem_cache_create("vm_area_struct", | |
1271 | sizeof(struct vm_area_struct), 0, | |
1272 | SLAB_PANIC, NULL, NULL); | |
1273 | mm_cachep = kmem_cache_create("mm_struct", | |
1274 | sizeof(struct mm_struct), 0, | |
1275 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); | |
1276 | } |