| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
| 2 | #ifndef _ASM_GENERIC_FUTEX_H |
| 3 | #define _ASM_GENERIC_FUTEX_H |
| 4 | |
| 5 | #include <linux/futex.h> |
| 6 | #include <linux/uaccess.h> |
| 7 | #include <asm/errno.h> |
| 8 | |
| 9 | #ifndef CONFIG_SMP |
| 10 | /* |
| 11 | * The following implementation only for uniprocessor machines. |
| 12 | * It relies on preempt_disable() ensuring mutual exclusion. |
| 13 | * |
| 14 | */ |
| 15 | |
| 16 | /** |
| 17 | * arch_futex_atomic_op_inuser() - Atomic arithmetic operation with constant |
| 18 | * argument and comparison of the previous |
| 19 | * futex value with another constant. |
| 20 | * |
| 21 | * @encoded_op: encoded operation to execute |
| 22 | * @uaddr: pointer to user space address |
| 23 | * |
| 24 | * Return: |
| 25 | * 0 - On success |
| David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame^] | 26 | * -EFAULT - User access resulted in a page fault |
| 27 | * -EAGAIN - Atomic operation was unable to complete due to contention |
| 28 | * -ENOSYS - Operation not supported |
| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 29 | */ |
| 30 | static inline int |
| 31 | arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr) |
| 32 | { |
| 33 | int oldval, ret; |
| 34 | u32 tmp; |
| 35 | |
| 36 | preempt_disable(); |
| 37 | pagefault_disable(); |
| 38 | |
| 39 | ret = -EFAULT; |
| 40 | if (unlikely(get_user(oldval, uaddr) != 0)) |
| 41 | goto out_pagefault_enable; |
| 42 | |
| 43 | ret = 0; |
| 44 | tmp = oldval; |
| 45 | |
| 46 | switch (op) { |
| 47 | case FUTEX_OP_SET: |
| 48 | tmp = oparg; |
| 49 | break; |
| 50 | case FUTEX_OP_ADD: |
| 51 | tmp += oparg; |
| 52 | break; |
| 53 | case FUTEX_OP_OR: |
| 54 | tmp |= oparg; |
| 55 | break; |
| 56 | case FUTEX_OP_ANDN: |
| 57 | tmp &= ~oparg; |
| 58 | break; |
| 59 | case FUTEX_OP_XOR: |
| 60 | tmp ^= oparg; |
| 61 | break; |
| 62 | default: |
| 63 | ret = -ENOSYS; |
| 64 | } |
| 65 | |
| 66 | if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0)) |
| 67 | ret = -EFAULT; |
| 68 | |
| 69 | out_pagefault_enable: |
| 70 | pagefault_enable(); |
| 71 | preempt_enable(); |
| 72 | |
| 73 | if (ret == 0) |
| 74 | *oval = oldval; |
| 75 | |
| 76 | return ret; |
| 77 | } |
| 78 | |
| 79 | /** |
| 80 | * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the |
| 81 | * uaddr with newval if the current value is |
| 82 | * oldval. |
| 83 | * @uval: pointer to store content of @uaddr |
| 84 | * @uaddr: pointer to user space address |
| 85 | * @oldval: old value |
| 86 | * @newval: new value to store to @uaddr |
| 87 | * |
| 88 | * Return: |
| 89 | * 0 - On success |
| David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame^] | 90 | * -EFAULT - User access resulted in a page fault |
| 91 | * -EAGAIN - Atomic operation was unable to complete due to contention |
| 92 | * -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG) |
| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 93 | */ |
| 94 | static inline int |
| 95 | futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, |
| 96 | u32 oldval, u32 newval) |
| 97 | { |
| 98 | u32 val; |
| 99 | |
| 100 | preempt_disable(); |
| 101 | if (unlikely(get_user(val, uaddr) != 0)) { |
| 102 | preempt_enable(); |
| 103 | return -EFAULT; |
| 104 | } |
| 105 | |
| 106 | if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) { |
| 107 | preempt_enable(); |
| 108 | return -EFAULT; |
| 109 | } |
| 110 | |
| 111 | *uval = val; |
| 112 | preempt_enable(); |
| 113 | |
| 114 | return 0; |
| 115 | } |
| 116 | |
| 117 | #else |
| 118 | static inline int |
| 119 | arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr) |
| 120 | { |
| David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame^] | 121 | return -ENOSYS; |
| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 122 | } |
| 123 | |
| 124 | static inline int |
| 125 | futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, |
| 126 | u32 oldval, u32 newval) |
| 127 | { |
| 128 | return -ENOSYS; |
| 129 | } |
| 130 | |
| 131 | #endif /* CONFIG_SMP */ |
| 132 | #endif |