1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_ARM_FUTEX_H
3 #define _ASM_ARM_FUTEX_H
7 #include <linux/futex.h>
8 #include <linux/uaccess.h>
11 #define __futex_atomic_ex_table(err_reg) \
13 " .pushsection __ex_table,\"a\"\n" \
15 " .long 1b, 4f, 2b, 4f\n" \
17 " .pushsection .text.fixup,\"ax\"\n" \
19 "4: mov %0, " err_reg "\n" \
25 #define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
27 unsigned int __ua_flags; \
30 __ua_flags = uaccess_save_and_enable(); \
31 __asm__ __volatile__( \
32 "1: ldrex %1, [%3]\n" \
34 "2: strex %2, %0, [%3]\n" \
38 __futex_atomic_ex_table("%5") \
39 : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \
40 : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
42 uaccess_restore(__ua_flags); \
46 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
47 u32 oldval, u32 newval)
49 unsigned int __ua_flags;
53 if (!access_ok(uaddr, sizeof(u32)))
57 /* Prefetching cannot fault */
59 __ua_flags = uaccess_save_and_enable();
60 __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
63 " ite eq @ explicit IT needed for the 2b label\n"
64 "2: strexeq %0, %3, [%4]\n"
68 __futex_atomic_ex_table("%5")
69 : "=&r" (ret), "=&r" (val)
70 : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
72 uaccess_restore(__ua_flags);
79 #else /* !SMP, we can work around lack of atomic ops by disabling preemption */
81 #include <linux/preempt.h>
82 #include <asm/domain.h>
84 #define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
86 unsigned int __ua_flags = uaccess_save_and_enable(); \
87 __asm__ __volatile__( \
88 "1: " TUSER(ldr) " %1, [%3]\n" \
90 "2: " TUSER(str) " %0, [%3]\n" \
92 __futex_atomic_ex_table("%5") \
93 : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \
94 : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
96 uaccess_restore(__ua_flags); \
100 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
101 u32 oldval, u32 newval)
103 unsigned int __ua_flags;
107 if (!access_ok(uaddr, sizeof(u32)))
111 __ua_flags = uaccess_save_and_enable();
112 __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
114 "1: " TUSER(ldr) " %1, [%4]\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)
122 uaccess_restore(__ua_flags);
133 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
135 int oldval = 0, ret, tmp;
144 __futex_atomic_op("mov %0, %4", ret, oldval, tmp, uaddr, oparg);
147 __futex_atomic_op("add %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
150 __futex_atomic_op("orr %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
153 __futex_atomic_op("and %0, %1, %4", ret, oldval, tmp, uaddr, ~oparg);
156 __futex_atomic_op("eor %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
168 * Store unconditionally. If ret != 0 the extra store is the least
169 * of the worries but GCC cannot figure out that __futex_atomic_op()
170 * is either setting ret to -EFAULT or storing the old value in
171 * oldval which results in a uninitialized warning at the call site.
178 #endif /* __KERNEL__ */
179 #endif /* _ASM_ARM_FUTEX_H */