1 | /* Copyright (C) 2008-2017 Free Software Foundation, Inc. |
2 | Contributed by Richard Henderson <rth@redhat.com>. |
3 | |
4 | This file is part of the GNU Transactional Memory Library (libitm). |
5 | |
6 | Libitm is free software; you can redistribute it and/or modify it |
7 | under the terms of the GNU General Public License as published by |
8 | the Free Software Foundation; either version 3 of the License, or |
9 | (at your option) any later version. |
10 | |
11 | Libitm is distributed in the hope that it will be useful, but WITHOUT ANY |
12 | WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS |
13 | FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
14 | more details. |
15 | |
16 | Under Section 7 of GPL version 3, you are granted additional |
17 | permissions described in the GCC Runtime Library Exception, version |
18 | 3.1, as published by the Free Software Foundation. |
19 | |
20 | You should have received a copy of the GNU General Public License and |
21 | a copy of the GCC Runtime Library Exception along with this program; |
22 | see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
23 | <http://www.gnu.org/licenses/>. */ |
24 | |
25 | /* Provide access to the futex system call. */ |
26 | |
27 | #include "libitm_i.h" |
28 | #include "futex.h" |
29 | #include <futex_bits.h> |
30 | #include <errno.h> |
31 | |
32 | namespace GTM HIDDEN { |
33 | |
34 | #define FUTEX_WAIT 0 |
35 | #define FUTEX_WAKE 1 |
36 | #define FUTEX_PRIVATE_FLAG 128 |
37 | |
38 | |
39 | static int gtm_futex_wait = FUTEX_WAIT | FUTEX_PRIVATE_FLAG; |
40 | static int gtm_futex_wake = FUTEX_WAKE | FUTEX_PRIVATE_FLAG; |
41 | |
42 | |
43 | void |
44 | futex_wait (std::atomic<int> *addr, int val) |
45 | { |
46 | long res; |
47 | |
48 | res = sys_futex0 (addr, gtm_futex_wait, val); |
49 | if (__builtin_expect (res == -ENOSYS, 0)) |
50 | { |
51 | gtm_futex_wait = FUTEX_WAIT; |
52 | gtm_futex_wake = FUTEX_WAKE; |
53 | res = sys_futex0 (addr, FUTEX_WAIT, val); |
54 | } |
55 | if (__builtin_expect (res < 0, 0)) |
56 | { |
57 | if (res == -EWOULDBLOCK || res == -ETIMEDOUT) |
58 | ; |
59 | else if (res == -EFAULT) |
60 | GTM_fatal ("futex failed (EFAULT %p)" , addr); |
61 | else |
62 | GTM_fatal ("futex failed (%s)" , strerror(-res)); |
63 | } |
64 | } |
65 | |
66 | |
67 | long |
68 | futex_wake (std::atomic<int> *addr, int count) |
69 | { |
70 | long res = sys_futex0 (addr, gtm_futex_wake, count); |
71 | if (__builtin_expect (res == -ENOSYS, 0)) |
72 | { |
73 | gtm_futex_wait = FUTEX_WAIT; |
74 | gtm_futex_wake = FUTEX_WAKE; |
75 | res = sys_futex0 (addr, FUTEX_WAKE, count); |
76 | } |
77 | if (__builtin_expect (res < 0, 0)) |
78 | GTM_fatal ("futex failed (%s)" , strerror(-res)); |
79 | else |
80 | return res; |
81 | } |
82 | |
83 | } // namespace GTM |
84 | |