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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ASM_ARM_FUTEX_H
3#define _ASM_ARM_FUTEX_H
4
5#ifdef __KERNEL__
6
7#include <linux/futex.h>
8#include <linux/uaccess.h>
9#include <asm/errno.h>
10
11#define __futex_atomic_ex_table(err_reg) \
12 "3:\n" \
13 " .pushsection __ex_table,\"a\"\n" \
14 " .align 3\n" \
15 " .long 1b, 4f, 2b, 4f\n" \
16 " .popsection\n" \
17 " .pushsection .text.fixup,\"ax\"\n" \
18 " .align 2\n" \
19 "4: mov %0, " err_reg "\n" \
20 " b 3b\n" \
21 " .popsection"
22
23#ifdef CONFIG_SMP
24
25#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
26({ \
27 unsigned int __ua_flags; \
28 smp_mb(); \
29 prefetchw(uaddr); \
30 __ua_flags = uaccess_save_and_enable(); \
31 __asm__ __volatile__( \
32 "1: ldrex %1, [%3]\n" \
33 " " insn "\n" \
34 "2: strex %2, %0, [%3]\n" \
35 " teq %2, #0\n" \
36 " bne 1b\n" \
37 " mov %0, #0\n" \
38 __futex_atomic_ex_table("%5") \
39 : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \
40 : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
41 : "cc", "memory"); \
42 uaccess_restore(__ua_flags); \
43})
44
45static inline int
46futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
47 u32 oldval, u32 newval)
48{
49 unsigned int __ua_flags;
50 int ret;
51 u32 val;
52
53 if (!access_ok(uaddr, sizeof(u32)))
54 return -EFAULT;
55
56 smp_mb();
57 /* Prefetching cannot fault */
58 prefetchw(uaddr);
59 __ua_flags = uaccess_save_and_enable();
60 __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
61 "1: ldrex %1, [%4]\n"
62 " teq %1, %2\n"
63 " ite eq @ explicit IT needed for the 2b label\n"
64 "2: strexeq %0, %3, [%4]\n"
65 " movne %0, #0\n"
66 " teq %0, #0\n"
67 " bne 1b\n"
68 __futex_atomic_ex_table("%5")
69 : "=&r" (ret), "=&r" (val)
70 : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
71 : "cc", "memory");
72 uaccess_restore(__ua_flags);
73 smp_mb();
74
75 *uval = val;
76 return ret;
77}
78
79#else /* !SMP, we can work around lack of atomic ops by disabling preemption */
80
81#include <linux/preempt.h>
82#include <asm/domain.h>
83
84#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
85({ \
86 unsigned int __ua_flags = uaccess_save_and_enable(); \
87 __asm__ __volatile__( \
88 "1: " TUSER(ldr) " %1, [%3]\n" \
89 " " insn "\n" \
90 "2: " TUSER(str) " %0, [%3]\n" \
91 " mov %0, #0\n" \
92 __futex_atomic_ex_table("%5") \
93 : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \
94 : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
95 : "cc", "memory"); \
96 uaccess_restore(__ua_flags); \
97})
98
99static inline int
100futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
101 u32 oldval, u32 newval)
102{
103 unsigned int __ua_flags;
104 int ret = 0;
105 u32 val;
106
107 if (!access_ok(uaddr, sizeof(u32)))
108 return -EFAULT;
109
110 preempt_disable();
111 __ua_flags = uaccess_save_and_enable();
112 __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
113 " .syntax unified\n"
114 "1: " TUSER(ldr) " %1, [%4]\n"
115 " teq %1, %2\n"
116 " it eq @ explicit IT needed for the 2b label\n"
117 "2: " TUSERCOND(str, eq) " %3, [%4]\n"
118 __futex_atomic_ex_table("%5")
119 : "+r" (ret), "=&r" (val)
120 : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
121 : "cc", "memory");
122 uaccess_restore(__ua_flags);
123
124 *uval = val;
125 preempt_enable();
126
127 return ret;
128}
129
130#endif /* !SMP */
131
132static inline int
133arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
134{
135 int oldval = 0, ret, tmp;
136
137 if (!access_ok(uaddr, sizeof(u32)))
138 return -EFAULT;
139
140#ifndef CONFIG_SMP
141 preempt_disable();
142#endif
143
144 switch (op) {
145 case FUTEX_OP_SET:
146 __futex_atomic_op("mov %0, %4", ret, oldval, tmp, uaddr, oparg);
147 break;
148 case FUTEX_OP_ADD:
149 __futex_atomic_op("add %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
150 break;
151 case FUTEX_OP_OR:
152 __futex_atomic_op("orr %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
153 break;
154 case FUTEX_OP_ANDN:
155 __futex_atomic_op("and %0, %1, %4", ret, oldval, tmp, uaddr, ~oparg);
156 break;
157 case FUTEX_OP_XOR:
158 __futex_atomic_op("eor %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
159 break;
160 default:
161 ret = -ENOSYS;
162 }
163
164#ifndef CONFIG_SMP
165 preempt_enable();
166#endif
167
168 /*
169 * Store unconditionally. If ret != 0 the extra store is the least
170 * of the worries but GCC cannot figure out that __futex_atomic_op()
171 * is either setting ret to -EFAULT or storing the old value in
172 * oldval which results in a uninitialized warning at the call site.
173 */
174 *oval = oldval;
175
176 return ret;
177}
178
179#endif /* __KERNEL__ */
180#endif /* _ASM_ARM_FUTEX_H */
1#ifndef _ASM_ARM_FUTEX_H
2#define _ASM_ARM_FUTEX_H
3
4#ifdef __KERNEL__
5
6#if defined(CONFIG_CPU_USE_DOMAINS) && defined(CONFIG_SMP)
7/* ARM doesn't provide unprivileged exclusive memory accessors */
8#include <asm-generic/futex.h>
9#else
10
11#include <linux/futex.h>
12#include <linux/uaccess.h>
13#include <asm/errno.h>
14
15#define __futex_atomic_ex_table(err_reg) \
16 "3:\n" \
17 " .pushsection __ex_table,\"a\"\n" \
18 " .align 3\n" \
19 " .long 1b, 4f, 2b, 4f\n" \
20 " .popsection\n" \
21 " .pushsection .fixup,\"ax\"\n" \
22 " .align 2\n" \
23 "4: mov %0, " err_reg "\n" \
24 " b 3b\n" \
25 " .popsection"
26
27#ifdef CONFIG_SMP
28
29#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
30 smp_mb(); \
31 __asm__ __volatile__( \
32 "1: ldrex %1, [%3]\n" \
33 " " insn "\n" \
34 "2: strex %2, %0, [%3]\n" \
35 " teq %2, #0\n" \
36 " bne 1b\n" \
37 " mov %0, #0\n" \
38 __futex_atomic_ex_table("%5") \
39 : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \
40 : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
41 : "cc", "memory")
42
43static inline int
44futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
45 u32 oldval, u32 newval)
46{
47 int ret;
48 u32 val;
49
50 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
51 return -EFAULT;
52
53 smp_mb();
54 __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
55 "1: ldrex %1, [%4]\n"
56 " teq %1, %2\n"
57 " ite eq @ explicit IT needed for the 2b label\n"
58 "2: strexeq %0, %3, [%4]\n"
59 " movne %0, #0\n"
60 " teq %0, #0\n"
61 " bne 1b\n"
62 __futex_atomic_ex_table("%5")
63 : "=&r" (ret), "=&r" (val)
64 : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
65 : "cc", "memory");
66 smp_mb();
67
68 *uval = val;
69 return ret;
70}
71
72#else /* !SMP, we can work around lack of atomic ops by disabling preemption */
73
74#include <linux/preempt.h>
75#include <asm/domain.h>
76
77#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
78 __asm__ __volatile__( \
79 "1: " TUSER(ldr) " %1, [%3]\n" \
80 " " insn "\n" \
81 "2: " TUSER(str) " %0, [%3]\n" \
82 " mov %0, #0\n" \
83 __futex_atomic_ex_table("%5") \
84 : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \
85 : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
86 : "cc", "memory")
87
88static inline int
89futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
90 u32 oldval, u32 newval)
91{
92 int ret = 0;
93 u32 val;
94
95 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
96 return -EFAULT;
97
98 __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
99 "1: " TUSER(ldr) " %1, [%4]\n"
100 " teq %1, %2\n"
101 " it eq @ explicit IT needed for the 2b label\n"
102 "2: " TUSER(streq) " %3, [%4]\n"
103 __futex_atomic_ex_table("%5")
104 : "+r" (ret), "=&r" (val)
105 : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
106 : "cc", "memory");
107
108 *uval = val;
109 return ret;
110}
111
112#endif /* !SMP */
113
114static inline int
115futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
116{
117 int op = (encoded_op >> 28) & 7;
118 int cmp = (encoded_op >> 24) & 15;
119 int oparg = (encoded_op << 8) >> 20;
120 int cmparg = (encoded_op << 20) >> 20;
121 int oldval = 0, ret, tmp;
122
123 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
124 oparg = 1 << oparg;
125
126 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
127 return -EFAULT;
128
129 pagefault_disable(); /* implies preempt_disable() */
130
131 switch (op) {
132 case FUTEX_OP_SET:
133 __futex_atomic_op("mov %0, %4", ret, oldval, tmp, uaddr, oparg);
134 break;
135 case FUTEX_OP_ADD:
136 __futex_atomic_op("add %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
137 break;
138 case FUTEX_OP_OR:
139 __futex_atomic_op("orr %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
140 break;
141 case FUTEX_OP_ANDN:
142 __futex_atomic_op("and %0, %1, %4", ret, oldval, tmp, uaddr, ~oparg);
143 break;
144 case FUTEX_OP_XOR:
145 __futex_atomic_op("eor %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
146 break;
147 default:
148 ret = -ENOSYS;
149 }
150
151 pagefault_enable(); /* subsumes preempt_enable() */
152
153 if (!ret) {
154 switch (cmp) {
155 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
156 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
157 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
158 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
159 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
160 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
161 default: ret = -ENOSYS;
162 }
163 }
164 return ret;
165}
166
167#endif /* !(CPU_USE_DOMAINS && SMP) */
168#endif /* __KERNEL__ */
169#endif /* _ASM_ARM_FUTEX_H */