Thumb-2: Implementation of the unified start-up and exceptions code
[linux-2.6.git] / arch / arm / include / asm / futex.h
1 #ifndef _ASM_ARM_FUTEX_H
2 #define _ASM_ARM_FUTEX_H
3
4 #ifdef __KERNEL__
5
6 #ifdef CONFIG_SMP
7
8 #include <asm-generic/futex.h>
9
10 #else /* !SMP, we can work around lack of atomic ops by disabling preemption */
11
12 #include <linux/futex.h>
13 #include <linux/preempt.h>
14 #include <linux/uaccess.h>
15 #include <asm/errno.h>
16
17 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)      \
18         __asm__ __volatile__(                                   \
19         "1:     ldrt    %1, [%2]\n"                             \
20         "       " insn "\n"                                     \
21         "2:     strt    %0, [%2]\n"                             \
22         "       mov     %0, #0\n"                               \
23         "3:\n"                                                  \
24         "       .section __ex_table,\"a\"\n"                    \
25         "       .align  3\n"                                    \
26         "       .long   1b, 4f, 2b, 4f\n"                       \
27         "       .previous\n"                                    \
28         "       .section .fixup,\"ax\"\n"                       \
29         "4:     mov     %0, %4\n"                               \
30         "       b       3b\n"                                   \
31         "       .previous"                                      \
32         : "=&r" (ret), "=&r" (oldval)                           \
33         : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT)              \
34         : "cc", "memory")
35
36 static inline int
37 futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
38 {
39         int op = (encoded_op >> 28) & 7;
40         int cmp = (encoded_op >> 24) & 15;
41         int oparg = (encoded_op << 8) >> 20;
42         int cmparg = (encoded_op << 20) >> 20;
43         int oldval = 0, ret;
44
45         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
46                 oparg = 1 << oparg;
47
48         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
49                 return -EFAULT;
50
51         pagefault_disable();    /* implies preempt_disable() */
52
53         switch (op) {
54         case FUTEX_OP_SET:
55                 __futex_atomic_op("mov  %0, %3", ret, oldval, uaddr, oparg);
56                 break;
57         case FUTEX_OP_ADD:
58                 __futex_atomic_op("add  %0, %1, %3", ret, oldval, uaddr, oparg);
59                 break;
60         case FUTEX_OP_OR:
61                 __futex_atomic_op("orr  %0, %1, %3", ret, oldval, uaddr, oparg);
62                 break;
63         case FUTEX_OP_ANDN:
64                 __futex_atomic_op("and  %0, %1, %3", ret, oldval, uaddr, ~oparg);
65                 break;
66         case FUTEX_OP_XOR:
67                 __futex_atomic_op("eor  %0, %1, %3", ret, oldval, uaddr, oparg);
68                 break;
69         default:
70                 ret = -ENOSYS;
71         }
72
73         pagefault_enable();     /* subsumes preempt_enable() */
74
75         if (!ret) {
76                 switch (cmp) {
77                 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
78                 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
79                 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
80                 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
81                 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
82                 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
83                 default: ret = -ENOSYS;
84                 }
85         }
86         return ret;
87 }
88
89 static inline int
90 futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
91 {
92         int val;
93
94         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
95                 return -EFAULT;
96
97         pagefault_disable();    /* implies preempt_disable() */
98
99         __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
100         "1:     ldrt    %0, [%3]\n"
101         "       teq     %0, %1\n"
102         "       it      eq      @ explicit IT needed for the 2b label\n"
103         "2:     streqt  %2, [%3]\n"
104         "3:\n"
105         "       .section __ex_table,\"a\"\n"
106         "       .align  3\n"
107         "       .long   1b, 4f, 2b, 4f\n"
108         "       .previous\n"
109         "       .section .fixup,\"ax\"\n"
110         "4:     mov     %0, %4\n"
111         "       b       3b\n"
112         "       .previous"
113         : "=&r" (val)
114         : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
115         : "cc", "memory");
116
117         pagefault_enable();     /* subsumes preempt_enable() */
118
119         return val;
120 }
121
122 #endif /* !SMP */
123
124 #endif /* __KERNEL__ */
125 #endif /* _ASM_ARM_FUTEX_H */