diff options
Diffstat (limited to 'kernel/futex_compat.c')
| -rw-r--r-- | kernel/futex_compat.c | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/kernel/futex_compat.c b/kernel/futex_compat.c new file mode 100644 index 0000000..04ac3a9 --- /dev/null +++ b/kernel/futex_compat.c @@ -0,0 +1,195 @@ +/* + * 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 <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, 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, next_pi, pip; + 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; + + if (!futex_cmpxchg_enabled) + return -ENOSYS; + + if (!pid) + head = current->compat_robust_list; + else { + struct task_struct *p; + + ret = -ESRCH; + read_lock(&tasklist_lock); + p = find_task_by_vpid(pid); + if (!p) + goto err_unlock; + ret = -EPERM; + if ((current->euid != p->euid) && (current->euid != p->uid) && + !capable(CAP_SYS_PTRACE)) + goto err_unlock; + head = p->compat_robust_list; + read_unlock(&tasklist_lock); + } + + if (put_user(sizeof(*head), len_ptr)) + return -EFAULT; + return put_user(ptr_to_compat(head), head_ptr); + +err_unlock: + read_unlock(&tasklist_lock); + + 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)) { + 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) + val2 = (int) (unsigned long) utime; + + return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); +} |
