diff options
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 1274 |
1 files changed, 1274 insertions, 0 deletions
diff --git a/kernel/fork.c b/kernel/fork.c new file mode 100644 index 00000000000..f42a17f8869 --- /dev/null +++ b/kernel/fork.c @@ -0,0 +1,1274 @@ +/* + * linux/kernel/fork.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +/* + * 'fork.c' contains the help-routines for the 'fork' system call + * (see also entry.S and others). + * Fork is rather simple, once you get the hang of it, but the memory + * management can be a bitch. See 'mm/memory.c': 'copy_page_range()' + */ + +#include <linux/config.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/unistd.h> +#include <linux/smp_lock.h> +#include <linux/module.h> +#include <linux/vmalloc.h> +#include <linux/completion.h> +#include <linux/namespace.h> +#include <linux/personality.h> +#include <linux/mempolicy.h> +#include <linux/sem.h> +#include <linux/file.h> +#include <linux/key.h> +#include <linux/binfmts.h> +#include <linux/mman.h> +#include <linux/fs.h> +#include <linux/cpu.h> +#include <linux/cpuset.h> +#include <linux/security.h> +#include <linux/swap.h> +#include <linux/syscalls.h> +#include <linux/jiffies.h> +#include <linux/futex.h> +#include <linux/ptrace.h> +#include <linux/mount.h> +#include <linux/audit.h> +#include <linux/profile.h> +#include <linux/rmap.h> +#include <linux/acct.h> + +#include <asm/pgtable.h> +#include <asm/pgalloc.h> +#include <asm/uaccess.h> +#include <asm/mmu_context.h> +#include <asm/cacheflush.h> +#include <asm/tlbflush.h> + +/* + * Protected counters by write_lock_irq(&tasklist_lock) + */ +unsigned long total_forks; /* Handle normal Linux uptimes. */ +int nr_threads; /* The idle threads do not count.. */ + +int max_threads; /* tunable limit on nr_threads */ + +DEFINE_PER_CPU(unsigned long, process_counts) = 0; + + __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ + +EXPORT_SYMBOL(tasklist_lock); + +int nr_processes(void) +{ + int cpu; + int total = 0; + + for_each_online_cpu(cpu) + total += per_cpu(process_counts, cpu); + + return total; +} + +#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR +# define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL) +# define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk)) +static kmem_cache_t *task_struct_cachep; +#endif + +/* SLAB cache for signal_struct structures (tsk->signal) */ +kmem_cache_t *signal_cachep; + +/* SLAB cache for sighand_struct structures (tsk->sighand) */ +kmem_cache_t *sighand_cachep; + +/* SLAB cache for files_struct structures (tsk->files) */ +kmem_cache_t *files_cachep; + +/* SLAB cache for fs_struct structures (tsk->fs) */ +kmem_cache_t *fs_cachep; + +/* SLAB cache for vm_area_struct structures */ +kmem_cache_t *vm_area_cachep; + +/* SLAB cache for mm_struct structures (tsk->mm) */ +static kmem_cache_t *mm_cachep; + +void free_task(struct task_struct *tsk) +{ + free_thread_info(tsk->thread_info); + free_task_struct(tsk); +} +EXPORT_SYMBOL(free_task); + +void __put_task_struct(struct task_struct *tsk) +{ + WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE))); + WARN_ON(atomic_read(&tsk->usage)); + WARN_ON(tsk == current); + + if (unlikely(tsk->audit_context)) + audit_free(tsk); + security_task_free(tsk); + free_uid(tsk->user); + put_group_info(tsk->group_info); + + if (!profile_handoff_task(tsk)) + free_task(tsk); +} + +void __init fork_init(unsigned long mempages) +{ +#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR +#ifndef ARCH_MIN_TASKALIGN +#define ARCH_MIN_TASKALIGN L1_CACHE_BYTES +#endif + /* create a slab on which task_structs can be allocated */ + task_struct_cachep = + kmem_cache_create("task_struct", sizeof(struct task_struct), + ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL); +#endif + + /* + * The default maximum number of threads is set to a safe + * value: the thread structures can take up at most half + * of memory. + */ + max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); + + /* + * we need to allow at least 20 threads to boot a system + */ + if(max_threads < 20) + max_threads = 20; + + init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; + init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; + init_task.signal->rlim[RLIMIT_SIGPENDING] = + init_task.signal->rlim[RLIMIT_NPROC]; +} + +static struct task_struct *dup_task_struct(struct task_struct *orig) +{ + struct task_struct *tsk; + struct thread_info *ti; + + prepare_to_copy(orig); + + tsk = alloc_task_struct(); + if (!tsk) + return NULL; + + ti = alloc_thread_info(tsk); + if (!ti) { + free_task_struct(tsk); + return NULL; + } + + *ti = *orig->thread_info; + *tsk = *orig; + tsk->thread_info = ti; + ti->task = tsk; + + /* One for us, one for whoever does the "release_task()" (usually parent) */ + atomic_set(&tsk->usage,2); + return tsk; +} + +#ifdef CONFIG_MMU +static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm) +{ + struct vm_area_struct * mpnt, *tmp, **pprev; + struct rb_node **rb_link, *rb_parent; + int retval; + unsigned long charge; + struct mempolicy *pol; + + down_write(&oldmm->mmap_sem); + flush_cache_mm(current->mm); + mm->locked_vm = 0; + mm->mmap = NULL; + mm->mmap_cache = NULL; + mm->free_area_cache = oldmm->mmap_base; + mm->map_count = 0; + set_mm_counter(mm, rss, 0); + set_mm_counter(mm, anon_rss, 0); + cpus_clear(mm->cpu_vm_mask); + mm->mm_rb = RB_ROOT; + rb_link = &mm->mm_rb.rb_node; + rb_parent = NULL; + pprev = &mm->mmap; + + for (mpnt = current->mm->mmap ; mpnt ; mpnt = mpnt->vm_next) { + struct file *file; + + if (mpnt->vm_flags & VM_DONTCOPY) { + __vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, + -vma_pages(mpnt)); + continue; + } + charge = 0; + if (mpnt->vm_flags & VM_ACCOUNT) { + unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; + if (security_vm_enough_memory(len)) + goto fail_nomem; + charge = len; + } + tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); + if (!tmp) + goto fail_nomem; + *tmp = *mpnt; + pol = mpol_copy(vma_policy(mpnt)); + retval = PTR_ERR(pol); + if (IS_ERR(pol)) + goto fail_nomem_policy; + vma_set_policy(tmp, pol); + tmp->vm_flags &= ~VM_LOCKED; + tmp->vm_mm = mm; + tmp->vm_next = NULL; + anon_vma_link(tmp); + file = tmp->vm_file; + if (file) { + struct inode *inode = file->f_dentry->d_inode; + get_file(file); + if (tmp->vm_flags & VM_DENYWRITE) + atomic_dec(&inode->i_writecount); + + /* insert tmp into the share list, just after mpnt */ + spin_lock(&file->f_mapping->i_mmap_lock); + tmp->vm_truncate_count = mpnt->vm_truncate_count; + flush_dcache_mmap_lock(file->f_mapping); + vma_prio_tree_add(tmp, mpnt); + flush_dcache_mmap_unlock(file->f_mapping); + spin_unlock(&file->f_mapping->i_mmap_lock); + } + + /* + * Link in the new vma and copy the page table entries: + * link in first so that swapoff can see swap entries, + * and try_to_unmap_one's find_vma find the new vma. + */ + spin_lock(&mm->page_table_lock); + *pprev = tmp; + pprev = &tmp->vm_next; + + __vma_link_rb(mm, tmp, rb_link, rb_parent); + rb_link = &tmp->vm_rb.rb_right; + rb_parent = &tmp->vm_rb; + + mm->map_count++; + retval = copy_page_range(mm, current->mm, tmp); + spin_unlock(&mm->page_table_lock); + + if (tmp->vm_ops && tmp->vm_ops->open) + tmp->vm_ops->open(tmp); + + if (retval) + goto out; + } + retval = 0; + +out: + flush_tlb_mm(current->mm); + up_write(&oldmm->mmap_sem); + return retval; +fail_nomem_policy: + kmem_cache_free(vm_area_cachep, tmp); +fail_nomem: + retval = -ENOMEM; + vm_unacct_memory(charge); + goto out; +} + +static inline int mm_alloc_pgd(struct mm_struct * mm) +{ + mm->pgd = pgd_alloc(mm); + if (unlikely(!mm->pgd)) + return -ENOMEM; + return 0; +} + +static inline void mm_free_pgd(struct mm_struct * mm) +{ + pgd_free(mm->pgd); +} +#else +#define dup_mmap(mm, oldmm) (0) +#define mm_alloc_pgd(mm) (0) +#define mm_free_pgd(mm) +#endif /* CONFIG_MMU */ + + __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); + +#define allocate_mm() (kmem_cache_alloc(mm_cachep, SLAB_KERNEL)) +#define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) + +#include <linux/init_task.h> + +static struct mm_struct * mm_init(struct mm_struct * mm) +{ + atomic_set(&mm->mm_users, 1); + atomic_set(&mm->mm_count, 1); + init_rwsem(&mm->mmap_sem); + INIT_LIST_HEAD(&mm->mmlist); + mm->core_waiters = 0; + mm->nr_ptes = 0; + spin_lock_init(&mm->page_table_lock); + rwlock_init(&mm->ioctx_list_lock); + mm->ioctx_list = NULL; + mm->default_kioctx = (struct kioctx)INIT_KIOCTX(mm->default_kioctx, *mm); + mm->free_area_cache = TASK_UNMAPPED_BASE; + + if (likely(!mm_alloc_pgd(mm))) { + mm->def_flags = 0; + return mm; + } + free_mm(mm); + return NULL; +} + +/* + * Allocate and initialize an mm_struct. + */ +struct mm_struct * mm_alloc(void) +{ + struct mm_struct * mm; + + mm = allocate_mm(); + if (mm) { + memset(mm, 0, sizeof(*mm)); + mm = mm_init(mm); + } + return mm; +} + +/* + * Called when the last reference to the mm + * is dropped: either by a lazy thread or by + * mmput. Free the page directory and the mm. + */ +void fastcall __mmdrop(struct mm_struct *mm) +{ + BUG_ON(mm == &init_mm); + mm_free_pgd(mm); + destroy_context(mm); + free_mm(mm); +} + +/* + * Decrement the use count and release all resources for an mm. + */ +void mmput(struct mm_struct *mm) +{ + if (atomic_dec_and_test(&mm->mm_users)) { + exit_aio(mm); + exit_mmap(mm); + if (!list_empty(&mm->mmlist)) { + spin_lock(&mmlist_lock); + list_del(&mm->mmlist); + spin_unlock(&mmlist_lock); + } + put_swap_token(mm); + mmdrop(mm); + } +} +EXPORT_SYMBOL_GPL(mmput); + +/** + * get_task_mm - acquire a reference to the task's mm + * + * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning + * this kernel workthread has transiently adopted a user mm with use_mm, + * to do its AIO) is not set and if so returns a reference to it, after + * bumping up the use count. User must release the mm via mmput() + * after use. Typically used by /proc and ptrace. + */ +struct mm_struct *get_task_mm(struct task_struct *task) +{ + struct mm_struct *mm; + + task_lock(task); + mm = task->mm; + if (mm) { + if (task->flags & PF_BORROWED_MM) + mm = NULL; + else + atomic_inc(&mm->mm_users); + } + task_unlock(task); + return mm; +} +EXPORT_SYMBOL_GPL(get_task_mm); + +/* Please note the differences between mmput and mm_release. + * mmput is called whenever we stop holding onto a mm_struct, + * error success whatever. + * + * mm_release is called after a mm_struct has been removed + * from the current process. + * + * This difference is important for error handling, when we + * only half set up a mm_struct for a new process and need to restore + * the old one. Because we mmput the new mm_struct before + * restoring the old one. . . + * Eric Biederman 10 January 1998 + */ +void mm_release(struct task_struct *tsk, struct mm_struct *mm) +{ + struct completion *vfork_done = tsk->vfork_done; + + /* Get rid of any cached register state */ + deactivate_mm(tsk, mm); + + /* notify parent sleeping on vfork() */ + if (vfork_done) { + tsk->vfork_done = NULL; + complete(vfork_done); + } + if (tsk->clear_child_tid && atomic_read(&mm->mm_users) > 1) { + u32 __user * tidptr = tsk->clear_child_tid; + tsk->clear_child_tid = NULL; + + /* + * We don't check the error code - if userspace has + * not set up a proper pointer then tough luck. + */ + put_user(0, tidptr); + sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0); + } +} + +static int copy_mm(unsigned long clone_flags, struct task_struct * tsk) +{ + struct mm_struct * mm, *oldmm; + int retval; + + tsk->min_flt = tsk->maj_flt = 0; + tsk->nvcsw = tsk->nivcsw = 0; + + tsk->mm = NULL; + tsk->active_mm = NULL; + + /* + * Are we cloning a kernel thread? + * + * We need to steal a active VM for that.. + */ + oldmm = current->mm; + if (!oldmm) + return 0; + + if (clone_flags & CLONE_VM) { + atomic_inc(&oldmm->mm_users); + mm = oldmm; + /* + * There are cases where the PTL is held to ensure no + * new threads start up in user mode using an mm, which + * allows optimizing out ipis; the tlb_gather_mmu code + * is an example. + */ + spin_unlock_wait(&oldmm->page_table_lock); + goto good_mm; + } + + retval = -ENOMEM; + mm = allocate_mm(); + if (!mm) + goto fail_nomem; + + /* Copy the current MM stuff.. */ + memcpy(mm, oldmm, sizeof(*mm)); + if (!mm_init(mm)) + goto fail_nomem; + + if (init_new_context(tsk,mm)) + goto fail_nocontext; + + retval = dup_mmap(mm, oldmm); + if (retval) + goto free_pt; + + mm->hiwater_rss = get_mm_counter(mm,rss); + mm->hiwater_vm = mm->total_vm; + +good_mm: + tsk->mm = mm; + tsk->active_mm = mm; + return 0; + +free_pt: + mmput(mm); +fail_nomem: + return retval; + +fail_nocontext: + /* + * If init_new_context() failed, we cannot use mmput() to free the mm + * because it calls destroy_context() + */ + mm_free_pgd(mm); + free_mm(mm); + return retval; +} + +static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old) +{ + struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL); + /* We don't need to lock fs - think why ;-) */ + if (fs) { + atomic_set(&fs->count, 1); + rwlock_init(&fs->lock); + fs->umask = old->umask; + read_lock(&old->lock); + fs->rootmnt = mntget(old->rootmnt); + fs->root = dget(old->root); + fs->pwdmnt = mntget(old->pwdmnt); + fs->pwd = dget(old->pwd); + if (old->altroot) { + fs->altrootmnt = mntget(old->altrootmnt); + fs->altroot = dget(old->altroot); + } else { + fs->altrootmnt = NULL; + fs->altroot = NULL; + } + read_unlock(&old->lock); + } + return fs; +} + +struct fs_struct *copy_fs_struct(struct fs_struct *old) +{ + return __copy_fs_struct(old); +} + +EXPORT_SYMBOL_GPL(copy_fs_struct); + +static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk) +{ + if (clone_flags & CLONE_FS) { + atomic_inc(¤t->fs->count); + return 0; + } + tsk->fs = __copy_fs_struct(current->fs); + if (!tsk->fs) + return -ENOMEM; + return 0; +} + +static int count_open_files(struct files_struct *files, int size) +{ + int i; + + /* Find the last open fd */ + for (i = size/(8*sizeof(long)); i > 0; ) { + if (files->open_fds->fds_bits[--i]) + break; + } + i = (i+1) * 8 * sizeof(long); + return i; +} + +static int copy_files(unsigned long clone_flags, struct task_struct * tsk) +{ + struct files_struct *oldf, *newf; + struct file **old_fds, **new_fds; + int open_files, size, i, error = 0, expand; + + /* + * A background process may not have any files ... + */ + oldf = current->files; + if (!oldf) + goto out; + + if (clone_flags & CLONE_FILES) { + atomic_inc(&oldf->count); + goto out; + } + + /* + * Note: we may be using current for both targets (See exec.c) + * This works because we cache current->files (old) as oldf. Don't + * break this. + */ + tsk->files = NULL; + error = -ENOMEM; + newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL); + if (!newf) + goto out; + + atomic_set(&newf->count, 1); + + spin_lock_init(&newf->file_lock); + newf->next_fd = 0; + newf->max_fds = NR_OPEN_DEFAULT; + newf->max_fdset = __FD_SETSIZE; + newf->close_on_exec = &newf->close_on_exec_init; + newf->open_fds = &newf->open_fds_init; + newf->fd = &newf->fd_array[0]; + + spin_lock(&oldf->file_lock); + + open_files = count_open_files(oldf, oldf->max_fdset); + expand = 0; + + /* + * Check whether we need to allocate a larger fd array or fd set. + * Note: we're not a clone task, so the open count won't change. + */ + if (open_files > newf->max_fdset) { + newf->max_fdset = 0; + expand = 1; + } + if (open_files > newf->max_fds) { + newf->max_fds = 0; + expand = 1; + } + + /* if the old fdset gets grown now, we'll only copy up to "size" fds */ + if (expand) { + spin_unlock(&oldf->file_lock); + spin_lock(&newf->file_lock); + error = expand_files(newf, open_files-1); + spin_unlock(&newf->file_lock); + if (error < 0) + goto out_release; + spin_lock(&oldf->file_lock); + } + + old_fds = oldf->fd; + new_fds = newf->fd; + + memcpy(newf->open_fds->fds_bits, oldf->open_fds->fds_bits, open_files/8); + memcpy(newf->close_on_exec->fds_bits, oldf->close_on_exec->fds_bits, open_files/8); + + for (i = open_files; i != 0; i--) { + struct file *f = *old_fds++; + if (f) { + get_file(f); + } else { + /* + * The fd may be claimed in the fd bitmap but not yet + * instantiated in the files array if a sibling thread + * is partway through open(). So make sure that this + * fd is available to the new process. + */ + FD_CLR(open_files - i, newf->open_fds); + } + *new_fds++ = f; + } + spin_unlock(&oldf->file_lock); + + /* compute the remainder to be cleared */ + size = (newf->max_fds - open_files) * sizeof(struct file *); + + /* This is long word aligned thus could use a optimized version */ + memset(new_fds, 0, size); + + if (newf->max_fdset > open_files) { + int left = (newf->max_fdset-open_files)/8; + int start = open_files / (8 * sizeof(unsigned long)); + + memset(&newf->open_fds->fds_bits[start], 0, left); + memset(&newf->close_on_exec->fds_bits[start], 0, left); + } + + tsk->files = newf; + error = 0; +out: + return error; + +out_release: + free_fdset (newf->close_on_exec, newf->max_fdset); + free_fdset (newf->open_fds, newf->max_fdset); + free_fd_array(newf->fd, newf->max_fds); + kmem_cache_free(files_cachep, newf); + goto out; +} + +/* + * Helper to unshare the files of the current task. + * We don't want to expose copy_files internals to + * the exec layer of the kernel. + */ + +int unshare_files(void) +{ + struct files_struct *files = current->files; + int rc; + + if(!files) + BUG(); + + /* This can race but the race causes us to copy when we don't + need to and drop the copy */ + if(atomic_read(&files->count) == 1) + { + atomic_inc(&files->count); + return 0; + } + rc = copy_files(0, current); + if(rc) + current->files = files; + return rc; +} + +EXPORT_SYMBOL(unshare_files); + +static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk) +{ + struct sighand_struct *sig; + + if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) { + atomic_inc(¤t->sighand->count); + return 0; + } + sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); + tsk->sighand = sig; + if (!sig) + return -ENOMEM; + spin_lock_init(&sig->siglock); + atomic_set(&sig->count, 1); + memcpy(sig->action, current->sighand->action, sizeof(sig->action)); + return 0; +} + +static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk) +{ + struct signal_struct *sig; + int ret; + + if (clone_flags & CLONE_THREAD) { + atomic_inc(¤t->signal->count); + atomic_inc(¤t->signal->live); + return 0; + } + sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL); + tsk->signal = sig; + if (!sig) + return -ENOMEM; + + ret = copy_thread_group_keys(tsk); + if (ret < 0) { + kmem_cache_free(signal_cachep, sig); + return ret; + } + + atomic_set(&sig->count, 1); + atomic_set(&sig->live, 1); + init_waitqueue_head(&sig->wait_chldexit); + sig->flags = 0; + sig->group_exit_code = 0; + sig->group_exit_task = NULL; + sig->group_stop_count = 0; + sig->curr_target = NULL; + init_sigpending(&sig->shared_pending); + INIT_LIST_HEAD(&sig->posix_timers); + + sig->it_real_value = sig->it_real_incr = 0; + sig->real_timer.function = it_real_fn; + sig->real_timer.data = (unsigned long) tsk; + init_timer(&sig->real_timer); + + sig->it_virt_expires = cputime_zero; + sig->it_virt_incr = cputime_zero; + sig->it_prof_expires = cputime_zero; + sig->it_prof_incr = cputime_zero; + + sig->tty = current->signal->tty; + sig->pgrp = process_group(current); + sig->session = current->signal->session; + sig->leader = 0; /* session leadership doesn't inherit */ + sig->tty_old_pgrp = 0; + + sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero; + sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0; + sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0; + sig->sched_time = 0; + INIT_LIST_HEAD(&sig->cpu_timers[0]); + INIT_LIST_HEAD(&sig->cpu_timers[1]); + INIT_LIST_HEAD(&sig->cpu_timers[2]); + + task_lock(current->group_leader); + memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); + task_unlock(current->group_leader); + + if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) { + /* + * New sole thread in the process gets an expiry time + * of the whole CPU time limit. + */ + tsk->it_prof_expires = + secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur); + } + + return 0; +} + +static inline void copy_flags(unsigned long clone_flags, struct task_struct *p) +{ + unsigned long new_flags = p->flags; + + new_flags &= ~PF_SUPERPRIV; + new_flags |= PF_FORKNOEXEC; + if (!(clone_flags & CLONE_PTRACE)) + p->ptrace = 0; + p->flags = new_flags; +} + +asmlinkage long sys_set_tid_address(int __user *tidptr) +{ + current->clear_child_tid = tidptr; + + return current->pid; +} + +/* + * This creates a new process as a copy of the old one, + * but does not actually start it yet. + * + * It copies the registers, and all the appropriate + * parts of the process environment (as per the clone + * flags). The actual kick-off is left to the caller. + */ +static task_t *copy_process(unsigned long clone_flags, + unsigned long stack_start, + struct pt_regs *regs, + unsigned long stack_size, + int __user *parent_tidptr, + int __user *child_tidptr, + int pid) +{ + int retval; + struct task_struct *p = NULL; + + if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) + return ERR_PTR(-EINVAL); + + /* + * Thread groups must share signals as well, and detached threads + * can only be started up within the thread group. + */ + if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) + return ERR_PTR(-EINVAL); + + /* + * Shared signal handlers imply shared VM. By way of the above, + * thread groups also imply shared VM. Blocking this case allows + * for various simplifications in other code. + */ + if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) + return ERR_PTR(-EINVAL); + + retval = security_task_create(clone_flags); + if (retval) + goto fork_out; + + retval = -ENOMEM; + p = dup_task_struct(current); + if (!p) + goto fork_out; + + retval = -EAGAIN; + if (atomic_read(&p->user->processes) >= + p->signal->rlim[RLIMIT_NPROC].rlim_cur) { + if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) && + p->user != &root_user) + goto bad_fork_free; + } + + atomic_inc(&p->user->__count); + atomic_inc(&p->user->processes); + get_group_info(p->group_info); + + /* + * If multiple threads are within copy_process(), then this check + * triggers too late. This doesn't hurt, the check is only there + * to stop root fork bombs. + */ + if (nr_threads >= max_threads) + goto bad_fork_cleanup_count; + + if (!try_module_get(p->thread_info->exec_domain->module)) + goto bad_fork_cleanup_count; + + if (p->binfmt && !try_module_get(p->binfmt->module)) + goto bad_fork_cleanup_put_domain; + + p->did_exec = 0; + copy_flags(clone_flags, p); + p->pid = pid; + retval = -EFAULT; + if (clone_flags & CLONE_PARENT_SETTID) + if (put_user(p->pid, parent_tidptr)) + goto bad_fork_cleanup; + + p->proc_dentry = NULL; + + INIT_LIST_HEAD(&p->children); + INIT_LIST_HEAD(&p->sibling); + p->vfork_done = NULL; + spin_lock_init(&p->alloc_lock); + spin_lock_init(&p->proc_lock); + + clear_tsk_thread_flag(p, TIF_SIGPENDING); + init_sigpending(&p->pending); + + p->utime = cputime_zero; + p->stime = cputime_zero; + p->sched_time = 0; + p->rchar = 0; /* I/O counter: bytes read */ + p->wchar = 0; /* I/O counter: bytes written */ + p->syscr = 0; /* I/O counter: read syscalls */ + p->syscw = 0; /* I/O counter: write syscalls */ + acct_clear_integrals(p); + + p->it_virt_expires = cputime_zero; + p->it_prof_expires = cputime_zero; + p->it_sched_expires = 0; + INIT_LIST_HEAD(&p->cpu_timers[0]); + INIT_LIST_HEAD(&p->cpu_timers[1]); + INIT_LIST_HEAD(&p->cpu_timers[2]); + + p->lock_depth = -1; /* -1 = no lock */ + do_posix_clock_monotonic_gettime(&p->start_time); + p->security = NULL; + p->io_context = NULL; + p->io_wait = NULL; + p->audit_context = NULL; +#ifdef CONFIG_NUMA + p->mempolicy = mpol_copy(p->mempolicy); + if (IS_ERR(p->mempolicy)) { + retval = PTR_ERR(p->mempolicy); + p->mempolicy = NULL; + goto bad_fork_cleanup; + } +#endif + + p->tgid = p->pid; + if (clone_flags & CLONE_THREAD) + p->tgid = current->tgid; + + if ((retval = security_task_alloc(p))) + goto bad_fork_cleanup_policy; + if ((retval = audit_alloc(p))) + goto bad_fork_cleanup_security; + /* copy all the process information */ + if ((retval = copy_semundo(clone_flags, p))) + goto bad_fork_cleanup_audit; + if ((retval = copy_files(clone_flags, p))) + goto bad_fork_cleanup_semundo; + if ((retval = copy_fs(clone_flags, p))) + goto bad_fork_cleanup_files; + if ((retval = copy_sighand(clone_flags, p))) + goto bad_fork_cleanup_fs; + if ((retval = copy_signal(clone_flags, p))) + goto bad_fork_cleanup_sighand; + if ((retval = copy_mm(clone_flags, p))) + goto bad_fork_cleanup_signal; + if ((retval = copy_keys(clone_flags, p))) + goto bad_fork_cleanup_mm; + if ((retval = copy_namespace(clone_flags, p))) + goto bad_fork_cleanup_keys; + retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs); + if (retval) + goto bad_fork_cleanup_namespace; + + p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; + /* + * Clear TID on mm_release()? + */ + p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL; + + /* + * Syscall tracing should be turned off in the child regardless + * of CLONE_PTRACE. + */ + clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); + + /* Our parent execution domain becomes current domain + These must match for thread signalling to apply */ + + p->parent_exec_id = p->self_exec_id; + + /* ok, now we should be set up.. */ + p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL); + p->pdeath_signal = 0; + p->exit_state = 0; + + /* Perform scheduler related setup */ + sched_fork(p); + + /* + * Ok, make it visible to the rest of the system. + * We dont wake it up yet. + */ + p->group_leader = p; + INIT_LIST_HEAD(&p->ptrace_children); + INIT_LIST_HEAD(&p->ptrace_list); + + /* Need tasklist lock for parent etc handling! */ + write_lock_irq(&tasklist_lock); + + /* + * The task hasn't been attached yet, so cpus_allowed mask cannot + * have changed. The cpus_allowed mask of the parent may have + * changed after it was copied first time, and it may then move to + * another CPU - so we re-copy it here and set the child's CPU to + * the parent's CPU. This avoids alot of nasty races. + */ + p->cpus_allowed = current->cpus_allowed; + set_task_cpu(p, smp_processor_id()); + + /* + * Check for pending SIGKILL! The new thread should not be allowed + * to slip out of an OOM kill. (or normal SIGKILL.) + */ + if (sigismember(¤t->pending.signal, SIGKILL)) { + write_unlock_irq(&tasklist_lock); + retval = -EINTR; + goto bad_fork_cleanup_namespace; + } + + /* CLONE_PARENT re-uses the old parent */ + if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) + p->real_parent = current->real_parent; + else + p->real_parent = current; + p->parent = p->real_parent; + + if (clone_flags & CLONE_THREAD) { + spin_lock(¤t->sighand->siglock); + /* + * Important: if an exit-all has been started then + * do not create this new thread - the whole thread + * group is supposed to exit anyway. + */ + if (current->signal->flags & SIGNAL_GROUP_EXIT) { + spin_unlock(¤t->sighand->siglock); + write_unlock_irq(&tasklist_lock); + retval = -EAGAIN; + goto bad_fork_cleanup_namespace; + } + p->group_leader = current->group_leader; + + if (current->signal->group_stop_count > 0) { + /* + * There is an all-stop in progress for the group. + * We ourselves will stop as soon as we check signals. + * Make the new thread part of that group stop too. + */ + current->signal->group_stop_count++; + set_tsk_thread_flag(p, TIF_SIGPENDING); + } + + if (!cputime_eq(current->signal->it_virt_expires, + cputime_zero) || + !cputime_eq(current->signal->it_prof_expires, + cputime_zero) || + current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY || + !list_empty(¤t->signal->cpu_timers[0]) || + !list_empty(¤t->signal->cpu_timers[1]) || + !list_empty(¤t->signal->cpu_timers[2])) { + /* + * Have child wake up on its first tick to check + * for process CPU timers. + */ + p->it_prof_expires = jiffies_to_cputime(1); + } + + spin_unlock(¤t->sighand->siglock); + } + + SET_LINKS(p); + if (unlikely(p->ptrace & PT_PTRACED)) + __ptrace_link(p, current->parent); + + cpuset_fork(p); + + attach_pid(p, PIDTYPE_PID, p->pid); + attach_pid(p, PIDTYPE_TGID, p->tgid); + if (thread_group_leader(p)) { + attach_pid(p, PIDTYPE_PGID, process_group(p)); + attach_pid(p, PIDTYPE_SID, p->signal->session); + if (p->pid) + __get_cpu_var(process_counts)++; + } + + nr_threads++; + total_forks++; + write_unlock_irq(&tasklist_lock); + retval = 0; + +fork_out: + if (retval) + return ERR_PTR(retval); + return p; + +bad_fork_cleanup_namespace: + exit_namespace(p); +bad_fork_cleanup_keys: + exit_keys(p); +bad_fork_cleanup_mm: + if (p->mm) + mmput(p->mm); +bad_fork_cleanup_signal: + exit_signal(p); +bad_fork_cleanup_sighand: + exit_sighand(p); +bad_fork_cleanup_fs: + exit_fs(p); /* blocking */ +bad_fork_cleanup_files: + exit_files(p); /* blocking */ +bad_fork_cleanup_semundo: + exit_sem(p); +bad_fork_cleanup_audit: + audit_free(p); +bad_fork_cleanup_security: + security_task_free(p); +bad_fork_cleanup_policy: +#ifdef CONFIG_NUMA + mpol_free(p->mempolicy); +#endif +bad_fork_cleanup: + if (p->binfmt) + module_put(p->binfmt->module); +bad_fork_cleanup_put_domain: + module_put(p->thread_info->exec_domain->module); +bad_fork_cleanup_count: + put_group_info(p->group_info); + atomic_dec(&p->user->processes); + free_uid(p->user); +bad_fork_free: + free_task(p); + goto fork_out; +} + +struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs) +{ + memset(regs, 0, sizeof(struct pt_regs)); + return regs; +} + +task_t * __devinit fork_idle(int cpu) +{ + task_t *task; + struct pt_regs regs; + + task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, NULL, 0); + if (!task) + return ERR_PTR(-ENOMEM); + init_idle(task, cpu); + unhash_process(task); + return task; +} + +static inline int fork_traceflag (unsigned clone_flags) +{ + if (clone_flags & CLONE_UNTRACED) + return 0; + else if (clone_flags & CLONE_VFORK) { + if (current->ptrace & PT_TRACE_VFORK) + return PTRACE_EVENT_VFORK; + } else if ((clone_flags & CSIGNAL) != SIGCHLD) { + if (current->ptrace & PT_TRACE_CLONE) + return PTRACE_EVENT_CLONE; + } else if (current->ptrace & PT_TRACE_FORK) + return PTRACE_EVENT_FORK; + + return 0; +} + +/* + * Ok, this is the main fork-routine. + * + * It copies the process, and if successful kick-starts + * it and waits for it to finish using the VM if required. + */ +long do_fork(unsigned long clone_flags, + unsigned long stack_start, + struct pt_regs *regs, + unsigned long stack_size, + int __user *parent_tidptr, + int __user *child_tidptr) +{ + struct task_struct *p; + int trace = 0; + long pid = alloc_pidmap(); + + if (pid < 0) + return -EAGAIN; + if (unlikely(current->ptrace)) { + trace = fork_traceflag (clone_flags); + if (trace) + clone_flags |= CLONE_PTRACE; + } + + p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, pid); + /* + * Do this prior waking up the new thread - the thread pointer + * might get invalid after that point, if the thread exits quickly. + */ + if (!IS_ERR(p)) { + struct completion vfork; + + if (clone_flags & CLONE_VFORK) { + p->vfork_done = &vfork; + init_completion(&vfork); + } + + if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) { + /* + * We'll start up with an immediate SIGSTOP. + */ + sigaddset(&p->pending.signal, SIGSTOP); + set_tsk_thread_flag(p, TIF_SIGPENDING); + } + + if (!(clone_flags & CLONE_STOPPED)) + wake_up_new_task(p, clone_flags); + else + p->state = TASK_STOPPED; + + if (unlikely (trace)) { + current->ptrace_message = pid; + ptrace_notify ((trace << 8) | SIGTRAP); + } + + if (clone_flags & CLONE_VFORK) { + wait_for_completion(&vfork); + if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE)) + ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP); + } + } else { + free_pidmap(pid); + pid = PTR_ERR(p); + } + return pid; +} + +void __init proc_caches_init(void) +{ + sighand_cachep = kmem_cache_create("sighand_cache", + sizeof(struct sighand_struct), 0, + SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); + signal_cachep = kmem_cache_create("signal_cache", + sizeof(struct signal_struct), 0, + SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); + files_cachep = kmem_cache_create("files_cache", + sizeof(struct files_struct), 0, + SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); + fs_cachep = kmem_cache_create("fs_cache", + sizeof(struct fs_struct), 0, + SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); + vm_area_cachep = kmem_cache_create("vm_area_struct", + sizeof(struct vm_area_struct), 0, + SLAB_PANIC, NULL, NULL); + mm_cachep = kmem_cache_create("mm_struct", + sizeof(struct mm_struct), 0, + SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); +} |