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/alternative.h> 25 #include <asm/cpufeature.h> 26 #include <asm/errno.h> 27 #include <asm/sysreg.h> 28 29 #define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg) \ 30 asm volatile( \ 31 ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \ 32 CONFIG_ARM64_PAN) \ 33 " prfm pstl1strm, %2\n" \ 34 "1: ldxr %w1, %2\n" \ 35 insn "\n" \ 36 "2: stlxr %w3, %w0, %2\n" \ 37 " cbnz %w3, 1b\n" \ 38 " dmb ish\n" \ 39 "3:\n" \ 40 " .pushsection .fixup,\"ax\"\n" \ 41 " .align 2\n" \ 42 "4: mov %w0, %w5\n" \ 43 " b 3b\n" \ 44 " .popsection\n" \ 45 _ASM_EXTABLE(1b, 4b) \ 46 _ASM_EXTABLE(2b, 4b) \ 47 ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, \ 48 CONFIG_ARM64_PAN) \ 49 : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp) \ 50 : "r" (oparg), "Ir" (-EFAULT) \ 51 : "memory") 52 53 static inline int 54 futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr) 55 { 56 int op = (encoded_op >> 28) & 7; 57 int cmp = (encoded_op >> 24) & 15; 58 int oparg = (encoded_op << 8) >> 20; 59 int cmparg = (encoded_op << 20) >> 20; 60 int oldval = 0, ret, tmp; 61 62 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) 63 oparg = 1 << oparg; 64 65 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))) 66 return -EFAULT; 67 68 pagefault_disable(); 69 70 switch (op) { 71 case FUTEX_OP_SET: 72 __futex_atomic_op("mov %w0, %w4", 73 ret, oldval, uaddr, tmp, oparg); 74 break; 75 case FUTEX_OP_ADD: 76 __futex_atomic_op("add %w0, %w1, %w4", 77 ret, oldval, uaddr, tmp, oparg); 78 break; 79 case FUTEX_OP_OR: 80 __futex_atomic_op("orr %w0, %w1, %w4", 81 ret, oldval, uaddr, tmp, oparg); 82 break; 83 case FUTEX_OP_ANDN: 84 __futex_atomic_op("and %w0, %w1, %w4", 85 ret, oldval, uaddr, tmp, ~oparg); 86 break; 87 case FUTEX_OP_XOR: 88 __futex_atomic_op("eor %w0, %w1, %w4", 89 ret, oldval, uaddr, tmp, oparg); 90 break; 91 default: 92 ret = -ENOSYS; 93 } 94 95 pagefault_enable(); 96 97 if (!ret) { 98 switch (cmp) { 99 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break; 100 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break; 101 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break; 102 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break; 103 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break; 104 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break; 105 default: ret = -ENOSYS; 106 } 107 } 108 return ret; 109 } 110 111 static inline int 112 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, 113 u32 oldval, u32 newval) 114 { 115 int ret = 0; 116 u32 val, tmp; 117 118 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))) 119 return -EFAULT; 120 121 asm volatile("// futex_atomic_cmpxchg_inatomic\n" 122 ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, CONFIG_ARM64_PAN) 123 " prfm pstl1strm, %2\n" 124 "1: ldxr %w1, %2\n" 125 " sub %w3, %w1, %w4\n" 126 " cbnz %w3, 3f\n" 127 "2: stlxr %w3, %w5, %2\n" 128 " cbnz %w3, 1b\n" 129 " dmb ish\n" 130 "3:\n" 131 " .pushsection .fixup,\"ax\"\n" 132 "4: mov %w0, %w6\n" 133 " b 3b\n" 134 " .popsection\n" 135 _ASM_EXTABLE(1b, 4b) 136 _ASM_EXTABLE(2b, 4b) 137 ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN) 138 : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp) 139 : "r" (oldval), "r" (newval), "Ir" (-EFAULT) 140 : "memory"); 141 142 *uval = val; 143 return ret; 144 } 145 146 #endif /* __KERNEL__ */ 147 #endif /* __ASM_FUTEX_H */ 148