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 45 static inline int 46 futex_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 99 static inline int 100 futex_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 "1: " TUSER(ldr) " %1, [%4]\n" 114 " teq %1, %2\n" 115 " it eq @ explicit IT needed for the 2b label\n" 116 "2: " TUSER(streq) " %3, [%4]\n" 117 __futex_atomic_ex_table("%5") 118 : "+r" (ret), "=&r" (val) 119 : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT) 120 : "cc", "memory"); 121 uaccess_restore(__ua_flags); 122 123 *uval = val; 124 preempt_enable(); 125 126 return ret; 127 } 128 129 #endif /* !SMP */ 130 131 static inline int 132 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) 133 { 134 int oldval = 0, ret, tmp; 135 136 #ifndef CONFIG_SMP 137 preempt_disable(); 138 #endif 139 pagefault_disable(); 140 141 switch (op) { 142 case FUTEX_OP_SET: 143 __futex_atomic_op("mov %0, %4", ret, oldval, tmp, uaddr, oparg); 144 break; 145 case FUTEX_OP_ADD: 146 __futex_atomic_op("add %0, %1, %4", ret, oldval, tmp, uaddr, oparg); 147 break; 148 case FUTEX_OP_OR: 149 __futex_atomic_op("orr %0, %1, %4", ret, oldval, tmp, uaddr, oparg); 150 break; 151 case FUTEX_OP_ANDN: 152 __futex_atomic_op("and %0, %1, %4", ret, oldval, tmp, uaddr, ~oparg); 153 break; 154 case FUTEX_OP_XOR: 155 __futex_atomic_op("eor %0, %1, %4", ret, oldval, tmp, uaddr, oparg); 156 break; 157 default: 158 ret = -ENOSYS; 159 } 160 161 pagefault_enable(); 162 #ifndef CONFIG_SMP 163 preempt_enable(); 164 #endif 165 166 if (!ret) 167 *oval = oldval; 168 169 return ret; 170 } 171 172 #endif /* __KERNEL__ */ 173 #endif /* _ASM_ARM_FUTEX_H */ 174