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(); \ 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, %w7\n" \ 29 "3:\n" \ 30 " dmb ish\n" \ 31 " .pushsection .fixup,\"ax\"\n" \ 32 " .align 2\n" \ 33 "4: mov %w0, %w6\n" \ 34 " b 3b\n" \ 35 " .popsection\n" \ 36 _ASM_EXTABLE(1b, 4b) \ 37 _ASM_EXTABLE(2b, 4b) \ 38 : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp), \ 39 "+r" (loops) \ 40 : "r" (oparg), "Ir" (-EFAULT), "Ir" (-EAGAIN) \ 41 : "memory"); \ 42 uaccess_disable(); \ 43 } while (0) 44 45 static inline int 46 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr) 47 { 48 int oldval = 0, ret, tmp; 49 u32 __user *uaddr = __uaccess_mask_ptr(_uaddr); 50 51 pagefault_disable(); 52 53 switch (op) { 54 case FUTEX_OP_SET: 55 __futex_atomic_op("mov %w3, %w5", 56 ret, oldval, uaddr, tmp, oparg); 57 break; 58 case FUTEX_OP_ADD: 59 __futex_atomic_op("add %w3, %w1, %w5", 60 ret, oldval, uaddr, tmp, oparg); 61 break; 62 case FUTEX_OP_OR: 63 __futex_atomic_op("orr %w3, %w1, %w5", 64 ret, oldval, uaddr, tmp, oparg); 65 break; 66 case FUTEX_OP_ANDN: 67 __futex_atomic_op("and %w3, %w1, %w5", 68 ret, oldval, uaddr, tmp, ~oparg); 69 break; 70 case FUTEX_OP_XOR: 71 __futex_atomic_op("eor %w3, %w1, %w5", 72 ret, oldval, uaddr, tmp, oparg); 73 break; 74 default: 75 ret = -ENOSYS; 76 } 77 78 pagefault_enable(); 79 80 if (!ret) 81 *oval = oldval; 82 83 return ret; 84 } 85 86 static inline int 87 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr, 88 u32 oldval, u32 newval) 89 { 90 int ret = 0; 91 unsigned int loops = FUTEX_MAX_LOOPS; 92 u32 val, tmp; 93 u32 __user *uaddr; 94 95 if (!access_ok(_uaddr, sizeof(u32))) 96 return -EFAULT; 97 98 uaddr = __uaccess_mask_ptr(_uaddr); 99 uaccess_enable(); 100 asm volatile("// futex_atomic_cmpxchg_inatomic\n" 101 " prfm pstl1strm, %2\n" 102 "1: ldxr %w1, %2\n" 103 " sub %w3, %w1, %w5\n" 104 " cbnz %w3, 4f\n" 105 "2: stlxr %w3, %w6, %2\n" 106 " cbz %w3, 3f\n" 107 " sub %w4, %w4, %w3\n" 108 " cbnz %w4, 1b\n" 109 " mov %w0, %w8\n" 110 "3:\n" 111 " dmb ish\n" 112 "4:\n" 113 " .pushsection .fixup,\"ax\"\n" 114 "5: mov %w0, %w7\n" 115 " b 4b\n" 116 " .popsection\n" 117 _ASM_EXTABLE(1b, 5b) 118 _ASM_EXTABLE(2b, 5b) 119 : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp), "+r" (loops) 120 : "r" (oldval), "r" (newval), "Ir" (-EFAULT), "Ir" (-EAGAIN) 121 : "memory"); 122 uaccess_disable(); 123 124 if (!ret) 125 *uval = val; 126 127 return ret; 128 } 129 130 #endif /* __ASM_FUTEX_H */ 131