1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * Copyright (C) 2012 ARM Ltd. 4 */ 5 #ifndef __ASM_FUTEX_H 6 #define __ASM_FUTEX_H 7 8 #include <linux/futex.h> 9 #include <linux/uaccess.h> 10 11 #include <asm/errno.h> 12 13 #define FUTEX_MAX_LOOPS 128 /* What's the largest number you can think of? */ 14 15 #define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg) \ 16 do { \ 17 unsigned int loops = FUTEX_MAX_LOOPS; \ 18 \ 19 uaccess_enable_privileged(); \ 20 asm volatile( \ 21 " prfm pstl1strm, %2\n" \ 22 "1: ldxr %w1, %2\n" \ 23 insn "\n" \ 24 "2: stlxr %w0, %w3, %2\n" \ 25 " cbz %w0, 3f\n" \ 26 " sub %w4, %w4, %w0\n" \ 27 " cbnz %w4, 1b\n" \ 28 " mov %w0, %w6\n" \ 29 "3:\n" \ 30 " dmb ish\n" \ 31 _ASM_EXTABLE_UACCESS_ERR(1b, 3b, %w0) \ 32 _ASM_EXTABLE_UACCESS_ERR(2b, 3b, %w0) \ 33 : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp), \ 34 "+r" (loops) \ 35 : "r" (oparg), "Ir" (-EAGAIN) \ 36 : "memory"); \ 37 uaccess_disable_privileged(); \ 38 } while (0) 39 40 static inline int 41 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr) 42 { 43 int oldval = 0, ret, tmp; 44 u32 __user *uaddr = __uaccess_mask_ptr(_uaddr); 45 46 if (!access_ok(_uaddr, sizeof(u32))) 47 return -EFAULT; 48 49 switch (op) { 50 case FUTEX_OP_SET: 51 __futex_atomic_op("mov %w3, %w5", 52 ret, oldval, uaddr, tmp, oparg); 53 break; 54 case FUTEX_OP_ADD: 55 __futex_atomic_op("add %w3, %w1, %w5", 56 ret, oldval, uaddr, tmp, oparg); 57 break; 58 case FUTEX_OP_OR: 59 __futex_atomic_op("orr %w3, %w1, %w5", 60 ret, oldval, uaddr, tmp, oparg); 61 break; 62 case FUTEX_OP_ANDN: 63 __futex_atomic_op("and %w3, %w1, %w5", 64 ret, oldval, uaddr, tmp, ~oparg); 65 break; 66 case FUTEX_OP_XOR: 67 __futex_atomic_op("eor %w3, %w1, %w5", 68 ret, oldval, uaddr, tmp, oparg); 69 break; 70 default: 71 ret = -ENOSYS; 72 } 73 74 if (!ret) 75 *oval = oldval; 76 77 return ret; 78 } 79 80 static inline int 81 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr, 82 u32 oldval, u32 newval) 83 { 84 int ret = 0; 85 unsigned int loops = FUTEX_MAX_LOOPS; 86 u32 val, tmp; 87 u32 __user *uaddr; 88 89 if (!access_ok(_uaddr, sizeof(u32))) 90 return -EFAULT; 91 92 uaddr = __uaccess_mask_ptr(_uaddr); 93 uaccess_enable_privileged(); 94 asm volatile("// futex_atomic_cmpxchg_inatomic\n" 95 " prfm pstl1strm, %2\n" 96 "1: ldxr %w1, %2\n" 97 " sub %w3, %w1, %w5\n" 98 " cbnz %w3, 4f\n" 99 "2: stlxr %w3, %w6, %2\n" 100 " cbz %w3, 3f\n" 101 " sub %w4, %w4, %w3\n" 102 " cbnz %w4, 1b\n" 103 " mov %w0, %w7\n" 104 "3:\n" 105 " dmb ish\n" 106 "4:\n" 107 _ASM_EXTABLE_UACCESS_ERR(1b, 4b, %w0) 108 _ASM_EXTABLE_UACCESS_ERR(2b, 4b, %w0) 109 : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp), "+r" (loops) 110 : "r" (oldval), "r" (newval), "Ir" (-EAGAIN) 111 : "memory"); 112 uaccess_disable_privileged(); 113 114 if (!ret) 115 *uval = val; 116 117 return ret; 118 } 119 120 #endif /* __ASM_FUTEX_H */ 121