1 /* 2 * Copyright (C) 2012 ARM Ltd. 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 11 * GNU General Public License for more details. 12 * 13 * You should have received a copy of the GNU General Public License 14 * along with this program. If not, see <http://www.gnu.org/licenses/>. 15 */ 16 #ifndef __ASM_FUTEX_H 17 #define __ASM_FUTEX_H 18 19 #ifdef __KERNEL__ 20 21 #include <linux/futex.h> 22 #include <linux/uaccess.h> 23 24 #include <asm/errno.h> 25 26 #define FUTEX_MAX_LOOPS 128 /* What's the largest number you can think of? */ 27 28 #define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg) \ 29 do { \ 30 unsigned int loops = FUTEX_MAX_LOOPS; \ 31 \ 32 uaccess_enable(); \ 33 asm volatile( \ 34 " prfm pstl1strm, %2\n" \ 35 "1: ldxr %w1, %2\n" \ 36 insn "\n" \ 37 "2: stlxr %w0, %w3, %2\n" \ 38 " cbz %w0, 3f\n" \ 39 " sub %w4, %w4, %w0\n" \ 40 " cbnz %w4, 1b\n" \ 41 " mov %w0, %w7\n" \ 42 "3:\n" \ 43 " dmb ish\n" \ 44 " .pushsection .fixup,\"ax\"\n" \ 45 " .align 2\n" \ 46 "4: mov %w0, %w6\n" \ 47 " b 3b\n" \ 48 " .popsection\n" \ 49 _ASM_EXTABLE(1b, 4b) \ 50 _ASM_EXTABLE(2b, 4b) \ 51 : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp), \ 52 "+r" (loops) \ 53 : "r" (oparg), "Ir" (-EFAULT), "Ir" (-EAGAIN) \ 54 : "memory"); \ 55 uaccess_disable(); \ 56 } while (0) 57 58 static inline int 59 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr) 60 { 61 int oldval = 0, ret, tmp; 62 u32 __user *uaddr = __uaccess_mask_ptr(_uaddr); 63 64 pagefault_disable(); 65 66 switch (op) { 67 case FUTEX_OP_SET: 68 __futex_atomic_op("mov %w3, %w5", 69 ret, oldval, uaddr, tmp, oparg); 70 break; 71 case FUTEX_OP_ADD: 72 __futex_atomic_op("add %w3, %w1, %w5", 73 ret, oldval, uaddr, tmp, oparg); 74 break; 75 case FUTEX_OP_OR: 76 __futex_atomic_op("orr %w3, %w1, %w5", 77 ret, oldval, uaddr, tmp, oparg); 78 break; 79 case FUTEX_OP_ANDN: 80 __futex_atomic_op("and %w3, %w1, %w5", 81 ret, oldval, uaddr, tmp, ~oparg); 82 break; 83 case FUTEX_OP_XOR: 84 __futex_atomic_op("eor %w3, %w1, %w5", 85 ret, oldval, uaddr, tmp, oparg); 86 break; 87 default: 88 ret = -ENOSYS; 89 } 90 91 pagefault_enable(); 92 93 if (!ret) 94 *oval = oldval; 95 96 return ret; 97 } 98 99 static inline int 100 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr, 101 u32 oldval, u32 newval) 102 { 103 int ret = 0; 104 unsigned int loops = FUTEX_MAX_LOOPS; 105 u32 val, tmp; 106 u32 __user *uaddr; 107 108 if (!access_ok(_uaddr, sizeof(u32))) 109 return -EFAULT; 110 111 uaddr = __uaccess_mask_ptr(_uaddr); 112 uaccess_enable(); 113 asm volatile("// futex_atomic_cmpxchg_inatomic\n" 114 " prfm pstl1strm, %2\n" 115 "1: ldxr %w1, %2\n" 116 " sub %w3, %w1, %w5\n" 117 " cbnz %w3, 4f\n" 118 "2: stlxr %w3, %w6, %2\n" 119 " cbz %w3, 3f\n" 120 " sub %w4, %w4, %w3\n" 121 " cbnz %w4, 1b\n" 122 " mov %w0, %w8\n" 123 "3:\n" 124 " dmb ish\n" 125 "4:\n" 126 " .pushsection .fixup,\"ax\"\n" 127 "5: mov %w0, %w7\n" 128 " b 4b\n" 129 " .popsection\n" 130 _ASM_EXTABLE(1b, 5b) 131 _ASM_EXTABLE(2b, 5b) 132 : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp), "+r" (loops) 133 : "r" (oldval), "r" (newval), "Ir" (-EFAULT), "Ir" (-EAGAIN) 134 : "memory"); 135 uaccess_disable(); 136 137 if (!ret) 138 *uval = val; 139 140 return ret; 141 } 142 143 #endif /* __KERNEL__ */ 144 #endif /* __ASM_FUTEX_H */ 145