| /* |
| * linux/kernel/futex_compat.c |
| * |
| * Futex compatibililty routines. |
| * |
| * Copyright 2006, Red Hat, Inc., Ingo Molnar |
| */ |
| |
| #include <linux/linkage.h> |
| #include <linux/compat.h> |
| #include <linux/nsproxy.h> |
| #include <linux/futex.h> |
| #include <linux/ptrace.h> |
| |
| #include <asm/uaccess.h> |
| |
| |
| /* |
| * Fetch a robust-list pointer. Bit 0 signals PI futexes: |
| */ |
| static inline int |
| fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **entry, |
| compat_uptr_t __user *head, unsigned int *pi) |
| { |
| if (get_user(*uentry, head)) |
| return -EFAULT; |
| |
| *entry = compat_ptr((*uentry) & ~1); |
| *pi = (unsigned int)(*uentry) & 1; |
| |
| return 0; |
| } |
| |
| static void __user *futex_uaddr(struct robust_list __user *entry, |
| compat_long_t futex_offset) |
| { |
| compat_uptr_t base = ptr_to_compat(entry); |
| void __user *uaddr = compat_ptr(base + futex_offset); |
| |
| return uaddr; |
| } |
| |
| /* |
| * Walk curr->robust_list (very carefully, it's a userspace list!) |
| * and mark any locks found there dead, and notify any waiters. |
| * |
| * We silently return on any sign of list-walking problem. |
| */ |
| void compat_exit_robust_list(struct task_struct *curr) |
| { |
| struct compat_robust_list_head __user *head = curr->compat_robust_list; |
| struct robust_list __user *entry, *next_entry, *pending; |
| unsigned int limit = ROBUST_LIST_LIMIT, pi, pip; |
| unsigned int uninitialized_var(next_pi); |
| compat_uptr_t uentry, next_uentry, upending; |
| compat_long_t futex_offset; |
| int rc; |
| |
| if (!futex_cmpxchg_enabled) |
| return; |
| |
| /* |
| * Fetch the list head (which was registered earlier, via |
| * sys_set_robust_list()): |
| */ |
| if (fetch_robust_entry(&uentry, &entry, &head->list.next, &pi)) |
| return; |
| /* |
| * Fetch the relative futex offset: |
| */ |
| if (get_user(futex_offset, &head->futex_offset)) |
| return; |
| /* |
| * Fetch any possibly pending lock-add first, and handle it |
| * if it exists: |
| */ |
| if (fetch_robust_entry(&upending, &pending, |
| &head->list_op_pending, &pip)) |
| return; |
| |
| next_entry = NULL; /* avoid warning with gcc */ |
| while (entry != (struct robust_list __user *) &head->list) { |
| /* |
| * Fetch the next entry in the list before calling |
| * handle_futex_death: |
| */ |
| rc = fetch_robust_entry(&next_uentry, &next_entry, |
| (compat_uptr_t __user *)&entry->next, &next_pi); |
| /* |
| * A pending lock might already be on the list, so |
| * dont process it twice: |
| */ |
| if (entry != pending) { |
| void __user *uaddr = futex_uaddr(entry, futex_offset); |
| |
| if (handle_futex_death(uaddr, curr, pi)) |
| return; |
| } |
| if (rc) |
| return; |
| uentry = next_uentry; |
| entry = next_entry; |
| pi = next_pi; |
| /* |
| * Avoid excessively long or circular lists: |
| */ |
| if (!--limit) |
| break; |
| |
| cond_resched(); |
| } |
| if (pending) { |
| void __user *uaddr = futex_uaddr(pending, futex_offset); |
| |
| handle_futex_death(uaddr, curr, pip); |
| } |
| } |
| |
| asmlinkage long |
| compat_sys_set_robust_list(struct compat_robust_list_head __user *head, |
| compat_size_t len) |
| { |
| if (!futex_cmpxchg_enabled) |
| return -ENOSYS; |
| |
| if (unlikely(len != sizeof(*head))) |
| return -EINVAL; |
| |
| current->compat_robust_list = head; |
| |
| return 0; |
| } |
| |
| asmlinkage long |
| compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr, |
| compat_size_t __user *len_ptr) |
| { |
| struct compat_robust_list_head __user *head; |
| unsigned long ret; |
| struct task_struct *p; |
| |
| if (!futex_cmpxchg_enabled) |
| return -ENOSYS; |
| |
| rcu_read_lock(); |
| |
| ret = -ESRCH; |
| if (!pid) |
| p = current; |
| else { |
| p = find_task_by_vpid(pid); |
| if (!p) |
| goto err_unlock; |
| } |
| |
| ret = -EPERM; |
| if (!ptrace_may_access(p, PTRACE_MODE_READ)) |
| goto err_unlock; |
| |
| head = p->compat_robust_list; |
| rcu_read_unlock(); |
| |
| if (put_user(sizeof(*head), len_ptr)) |
| return -EFAULT; |
| return put_user(ptr_to_compat(head), head_ptr); |
| |
| err_unlock: |
| rcu_read_unlock(); |
| |
| return ret; |
| } |
| |
| asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, u32 val, |
| struct compat_timespec __user *utime, u32 __user *uaddr2, |
| u32 val3) |
| { |
| struct timespec ts; |
| ktime_t t, *tp = NULL; |
| int val2 = 0; |
| int cmd = op & FUTEX_CMD_MASK; |
| |
| if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || |
| cmd == FUTEX_WAIT_BITSET || |
| cmd == FUTEX_WAIT_REQUEUE_PI)) { |
| if (get_compat_timespec(&ts, utime)) |
| return -EFAULT; |
| if (!timespec_valid(&ts)) |
| return -EINVAL; |
| |
| t = timespec_to_ktime(ts); |
| if (cmd == FUTEX_WAIT) |
| t = ktime_add_safe(ktime_get(), t); |
| tp = &t; |
| } |
| if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || |
| cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP) |
| val2 = (int) (unsigned long) utime; |
| |
| return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); |
| } |