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Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1#ifndef _ASM_ARM_FUTEX_H
2#define _ASM_ARM_FUTEX_H
3
4#ifdef __KERNEL__
5
6#include <linux/futex.h>
7#include <linux/uaccess.h>
8#include <asm/errno.h>
9
10#define __futex_atomic_ex_table(err_reg) \
11 "3:\n" \
12 " .pushsection __ex_table,\"a\"\n" \
13 " .align 3\n" \
14 " .long 1b, 4f, 2b, 4f\n" \
15 " .popsection\n" \
16 " .pushsection .text.fixup,\"ax\"\n" \
17 " .align 2\n" \
18 "4: mov %0, " err_reg "\n" \
19 " b 3b\n" \
20 " .popsection"
21
22#ifdef CONFIG_SMP
23
24#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
25 smp_mb(); \
26 prefetchw(uaddr); \
27 __asm__ __volatile__( \
28 "1: ldrex %1, [%3]\n" \
29 " " insn "\n" \
30 "2: strex %2, %0, [%3]\n" \
31 " teq %2, #0\n" \
32 " bne 1b\n" \
33 " mov %0, #0\n" \
34 __futex_atomic_ex_table("%5") \
35 : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \
36 : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
37 : "cc", "memory")
38
39static inline int
40futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
41 u32 oldval, u32 newval)
42{
43 int ret;
44 u32 val;
45
46 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
47 return -EFAULT;
48
49 smp_mb();
50 /* Prefetching cannot fault */
51 prefetchw(uaddr);
52 __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
53 "1: ldrex %1, [%4]\n"
54 " teq %1, %2\n"
55 " ite eq @ explicit IT needed for the 2b label\n"
56 "2: strexeq %0, %3, [%4]\n"
57 " movne %0, #0\n"
58 " teq %0, #0\n"
59 " bne 1b\n"
60 __futex_atomic_ex_table("%5")
61 : "=&r" (ret), "=&r" (val)
62 : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
63 : "cc", "memory");
64 smp_mb();
65
66 *uval = val;
67 return ret;
68}
69
70#else /* !SMP, we can work around lack of atomic ops by disabling preemption */
71
72#include <linux/preempt.h>
73#include <asm/domain.h>
74
75#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
76 __asm__ __volatile__( \
77 "1: " TUSER(ldr) " %1, [%3]\n" \
78 " " insn "\n" \
79 "2: " TUSER(str) " %0, [%3]\n" \
80 " mov %0, #0\n" \
81 __futex_atomic_ex_table("%5") \
82 : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \
83 : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
84 : "cc", "memory")
85
86static inline int
87futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
88 u32 oldval, u32 newval)
89{
90 int ret = 0;
91 u32 val;
92
93 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
94 return -EFAULT;
95
96 preempt_disable();
97 __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
98 "1: " TUSER(ldr) " %1, [%4]\n"
99 " teq %1, %2\n"
100 " it eq @ explicit IT needed for the 2b label\n"
101 "2: " TUSER(streq) " %3, [%4]\n"
102 __futex_atomic_ex_table("%5")
103 : "+r" (ret), "=&r" (val)
104 : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
105 : "cc", "memory");
106
107 *uval = val;
108 preempt_enable();
109
110 return ret;
111}
112
113#endif /* !SMP */
114
115static inline int
116futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
117{
118 int op = (encoded_op >> 28) & 7;
119 int cmp = (encoded_op >> 24) & 15;
120 int oparg = (encoded_op << 8) >> 20;
121 int cmparg = (encoded_op << 20) >> 20;
122 int oldval = 0, ret, tmp;
123
124 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
125 oparg = 1 << oparg;
126
127 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
128 return -EFAULT;
129
130#ifndef CONFIG_SMP
131 preempt_disable();
132#endif
133 pagefault_disable();
134
135 switch (op) {
136 case FUTEX_OP_SET:
137 __futex_atomic_op("mov %0, %4", ret, oldval, tmp, uaddr, oparg);
138 break;
139 case FUTEX_OP_ADD:
140 __futex_atomic_op("add %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
141 break;
142 case FUTEX_OP_OR:
143 __futex_atomic_op("orr %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
144 break;
145 case FUTEX_OP_ANDN:
146 __futex_atomic_op("and %0, %1, %4", ret, oldval, tmp, uaddr, ~oparg);
147 break;
148 case FUTEX_OP_XOR:
149 __futex_atomic_op("eor %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
150 break;
151 default:
152 ret = -ENOSYS;
153 }
154
155 pagefault_enable();
156#ifndef CONFIG_SMP
157 preempt_enable();
158#endif
159
160 if (!ret) {
161 switch (cmp) {
162 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
163 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
164 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
165 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
166 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
167 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
168 default: ret = -ENOSYS;
169 }
170 }
171 return ret;
172}
173
174#endif /* __KERNEL__ */
175#endif /* _ASM_ARM_FUTEX_H */