futex_compat.c

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    1 /*
    2  * linux/kernel/futex_compat.c
    3  *
    4  * Futex compatibililty routines.
    5  *
    6  * Copyright 2006, Red Hat, Inc., Ingo Molnar
    7  */
    8 
    9 #include <linux/linkage.h>
   10 #include <linux/compat.h>
   11 #include <linux/nsproxy.h>
   12 #include <linux/futex.h>
   13 #include <linux/ptrace.h>
   14 
   15 #include <asm/uaccess.h>
   16 
   17 
   18 /*
   19  * Fetch a robust-list pointer. Bit 0 signals PI futexes:
   20  */
   21 static inline int
   22 fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **entry,
   23                    compat_uptr_t __user *head, unsigned int *pi)
   24 {
   25         if (get_user(*uentry, head))
   26                 return -EFAULT;
   27 
   28         *entry = compat_ptr((*uentry) & ~1);
   29         *pi = (unsigned int)(*uentry) & 1;
   30 
   31         return 0;
   32 }
   33 
   34 static void __user *futex_uaddr(struct robust_list __user *entry,
   35                                 compat_long_t futex_offset)
   36 {
   37         compat_uptr_t base = ptr_to_compat(entry);
   38         void __user *uaddr = compat_ptr(base + futex_offset);
   39 
   40         return uaddr;
   41 }
   42 
   43 /*
   44  * Walk curr->robust_list (very carefully, it's a userspace list!)
   45  * and mark any locks found there dead, and notify any waiters.
   46  *
   47  * We silently return on any sign of list-walking problem.
   48  */
   49 void compat_exit_robust_list(struct task_struct *curr)
   50 {
   51         struct compat_robust_list_head __user *head = curr->compat_robust_list;
   52         struct robust_list __user *entry, *next_entry, *pending;
   53         unsigned int limit = ROBUST_LIST_LIMIT, pi, pip;
   54         unsigned int uninitialized_var(next_pi);
   55         compat_uptr_t uentry, next_uentry, upending;
   56         compat_long_t futex_offset;
   57         int rc;
   58 
   59         if (!futex_cmpxchg_enabled)
   60                 return;
   61 
   62         /*
   63          * Fetch the list head (which was registered earlier, via
   64          * sys_set_robust_list()):
   65          */
   66         if (fetch_robust_entry(&uentry, &entry, &head->list.next, &pi))
   67                 return;
   68         /*
   69          * Fetch the relative futex offset:
   70          */
   71         if (get_user(futex_offset, &head->futex_offset))
   72                 return;
   73         /*
   74          * Fetch any possibly pending lock-add first, and handle it
   75          * if it exists:
   76          */
   77         if (fetch_robust_entry(&upending, &pending,
   78                                &head->list_op_pending, &pip))
   79                 return;
   80 
   81         next_entry = NULL;      /* avoid warning with gcc */
   82         while (entry != (struct robust_list __user *) &head->list) {
   83                 /*
   84                  * Fetch the next entry in the list before calling
   85                  * handle_futex_death:
   86                  */
   87                 rc = fetch_robust_entry(&next_uentry, &next_entry,
   88                         (compat_uptr_t __user *)&entry->next, &next_pi);
   89                 /*
   90                  * A pending lock might already be on the list, so
   91                  * dont process it twice:
   92                  */
   93                 if (entry != pending) {
   94                         void __user *uaddr = futex_uaddr(entry, futex_offset);
   95 
   96                         if (handle_futex_death(uaddr, curr, pi))
   97                                 return;
   98                 }
   99                 if (rc)
  100                         return;
  101                 uentry = next_uentry;
  102                 entry = next_entry;
  103                 pi = next_pi;
  104                 /*
  105                  * Avoid excessively long or circular lists:
  106                  */
  107                 if (!--limit)
  108                         break;
  109 
  110                 cond_resched();
  111         }
  112         if (pending) {
  113                 void __user *uaddr = futex_uaddr(pending, futex_offset);
  114 
  115                 handle_futex_death(uaddr, curr, pip);
  116         }
  117 }
  118 
  119 asmlinkage long
  120 compat_sys_set_robust_list(struct compat_robust_list_head __user *head,
  121                            compat_size_t len)
  122 {
  123         if (!futex_cmpxchg_enabled)
  124                 return -ENOSYS;
  125 
  126         if (unlikely(len != sizeof(*head)))
  127                 return -EINVAL;
  128 
  129         current->compat_robust_list = head;
  130 
  131         return 0;
  132 }
  133 
  134 asmlinkage long
  135 compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr,
  136                            compat_size_t __user *len_ptr)
  137 {
  138         struct compat_robust_list_head __user *head;
  139         unsigned long ret;
  140         struct task_struct *p;
  141 
  142         if (!futex_cmpxchg_enabled)
  143                 return -ENOSYS;
  144 
  145         WARN_ONCE(1, "deprecated: get_robust_list will be deleted in 2013.\n");
  146 
  147         rcu_read_lock();
  148 
  149         ret = -ESRCH;
  150         if (!pid)
  151                 p = current;
  152         else {
  153                 p = find_task_by_vpid(pid);
  154                 if (!p)
  155                         goto err_unlock;
  156         }
  157 
  158         ret = -EPERM;
  159         if (!ptrace_may_access(p, PTRACE_MODE_READ))
  160                 goto err_unlock;
  161 
  162         head = p->compat_robust_list;
  163         rcu_read_unlock();
  164 
  165         if (put_user(sizeof(*head), len_ptr))
  166                 return -EFAULT;
  167         return put_user(ptr_to_compat(head), head_ptr);
  168 
  169 err_unlock:
  170         rcu_read_unlock();
  171 
  172         return ret;
  173 }
  174 
  175 asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, u32 val,
  176                 struct compat_timespec __user *utime, u32 __user *uaddr2,
  177                 u32 val3)
  178 {
  179         struct timespec ts;
  180         ktime_t t, *tp = NULL;
  181         int val2 = 0;
  182         int cmd = op & FUTEX_CMD_MASK;
  183 
  184         if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI ||
  185                       cmd == FUTEX_WAIT_BITSET ||
  186                       cmd == FUTEX_WAIT_REQUEUE_PI)) {
  187                 if (get_compat_timespec(&ts, utime))
  188                         return -EFAULT;
  189                 if (!timespec_valid(&ts))
  190                         return -EINVAL;
  191 
  192                 t = timespec_to_ktime(ts);
  193                 if (cmd == FUTEX_WAIT)
  194                         t = ktime_add_safe(ktime_get(), t);
  195                 tp = &t;
  196         }
  197         if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||
  198             cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP)
  199                 val2 = (int) (unsigned long) utime;
  200 
  201         return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
  202 }

Cache object: 725275871d7d17c2c98d47c7e18bb073

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FreeBSD/Linux Kernel Cross Reference sys/kernel/futex_compat.c

FreeBSD/Linux Kernel Cross Reference
sys/kernel/futex_compat.c