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/futex.h> 12 13#include <asm/uaccess.h> 14 15 16/* 17 * Fetch a robust-list pointer. Bit 0 signals PI futexes: 18 */ 19static inline int 20fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **entry, 21 compat_uptr_t __user *head, int *pi) 22{ 23 if (get_user(*uentry, head)) 24 return -EFAULT; 25 26 *entry = compat_ptr((*uentry) & ~1); 27 *pi = (unsigned int)(*uentry) & 1; 28 29 return 0; 30} 31 32/* 33 * Walk curr->robust_list (very carefully, it's a userspace list!) 34 * and mark any locks found there dead, and notify any waiters. 35 * 36 * We silently return on any sign of list-walking problem. 37 */ 38void compat_exit_robust_list(struct task_struct *curr) 39{ 40 struct compat_robust_list_head __user *head = curr->compat_robust_list; 41 struct robust_list __user *entry, *pending; 42 unsigned int limit = ROBUST_LIST_LIMIT, pi, pip; 43 compat_uptr_t uentry, upending; 44 compat_long_t futex_offset; 45 46 /* 47 * Fetch the list head (which was registered earlier, via 48 * sys_set_robust_list()): 49 */ 50 if (fetch_robust_entry(&uentry, &entry, &head->list.next, &pi)) 51 return; 52 /* 53 * Fetch the relative futex offset: 54 */ 55 if (get_user(futex_offset, &head->futex_offset)) 56 return; 57 /* 58 * Fetch any possibly pending lock-add first, and handle it 59 * if it exists: 60 */ 61 if (fetch_robust_entry(&upending, &pending, 62 &head->list_op_pending, &pip)) 63 return; 64 if (upending) 65 handle_futex_death((void __user *)pending + futex_offset, curr, pip); 66 67 while (compat_ptr(uentry) != &head->list) { 68 /* 69 * A pending lock might already be on the list, so 70 * dont process it twice: 71 */ 72 if (entry != pending) 73 if (handle_futex_death((void __user *)entry + futex_offset, 74 curr, pi)) 75 return; 76 77 /* 78 * Fetch the next entry in the list: 79 */ 80 if (fetch_robust_entry(&uentry, &entry, 81 (compat_uptr_t __user *)&entry->next, &pi)) 82 return; 83 /* 84 * Avoid excessively long or circular lists: 85 */ 86 if (!--limit) 87 break; 88 89 cond_resched(); 90 } 91} 92 93asmlinkage long 94compat_sys_set_robust_list(struct compat_robust_list_head __user *head, 95 compat_size_t len) 96{ 97 if (unlikely(len != sizeof(*head))) 98 return -EINVAL; 99 100 current->compat_robust_list = head; 101 102 return 0; 103} 104 105asmlinkage long 106compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr, 107 compat_size_t __user *len_ptr) 108{ 109 struct compat_robust_list_head __user *head; 110 unsigned long ret; 111 112 if (!pid) 113 head = current->compat_robust_list; 114 else { 115 struct task_struct *p; 116 117 ret = -ESRCH; 118 read_lock(&tasklist_lock); 119 p = find_task_by_pid(pid); 120 if (!p) 121 goto err_unlock; 122 ret = -EPERM; 123 if ((current->euid != p->euid) && (current->euid != p->uid) && 124 !capable(CAP_SYS_PTRACE)) 125 goto err_unlock; 126 head = p->compat_robust_list; 127 read_unlock(&tasklist_lock); 128 } 129 130 if (put_user(sizeof(*head), len_ptr)) 131 return -EFAULT; 132 return put_user(ptr_to_compat(head), head_ptr); 133 134err_unlock: 135 read_unlock(&tasklist_lock); 136 137 return ret; 138} 139 140asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, u32 val, 141 struct compat_timespec __user *utime, u32 __user *uaddr2, 142 u32 val3) 143{ 144 struct timespec ts; 145 ktime_t t, *tp = NULL; 146 int val2 = 0; 147 int cmd = op & FUTEX_CMD_MASK; 148 149 if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI)) { 150 if (get_compat_timespec(&ts, utime)) 151 return -EFAULT; 152 if (!timespec_valid(&ts)) 153 return -EINVAL; 154 155 t = timespec_to_ktime(ts); 156 if (cmd == FUTEX_WAIT) 157 t = ktime_add(ktime_get(), t); 158 tp = &t; 159 } 160 if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE) 161 val2 = (int) (unsigned long) utime; 162 163 return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); 164} 165