1 /* 2 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 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 * Vineetg: August 2010: From Android kernel work 9 */ 10 11 #ifndef _ASM_FUTEX_H 12 #define _ASM_FUTEX_H 13 14 #include <linux/futex.h> 15 #include <linux/preempt.h> 16 #include <linux/uaccess.h> 17 #include <asm/errno.h> 18 19 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\ 20 \ 21 __asm__ __volatile__( \ 22 "1: ld %1, [%2] \n" \ 23 insn "\n" \ 24 "2: st %0, [%2] \n" \ 25 " mov %0, 0 \n" \ 26 "3: \n" \ 27 " .section .fixup,\"ax\" \n" \ 28 " .align 4 \n" \ 29 "4: mov %0, %4 \n" \ 30 " b 3b \n" \ 31 " .previous \n" \ 32 " .section __ex_table,\"a\" \n" \ 33 " .align 4 \n" \ 34 " .word 1b, 4b \n" \ 35 " .word 2b, 4b \n" \ 36 " .previous \n" \ 37 \ 38 : "=&r" (ret), "=&r" (oldval) \ 39 : "r" (uaddr), "r" (oparg), "ir" (-EFAULT) \ 40 : "cc", "memory") 41 42 static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr) 43 { 44 int op = (encoded_op >> 28) & 7; 45 int cmp = (encoded_op >> 24) & 15; 46 int oparg = (encoded_op << 8) >> 20; 47 int cmparg = (encoded_op << 20) >> 20; 48 int oldval = 0, ret; 49 50 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) 51 oparg = 1 << oparg; 52 53 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) 54 return -EFAULT; 55 56 pagefault_disable(); /* implies preempt_disable() */ 57 58 switch (op) { 59 case FUTEX_OP_SET: 60 __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg); 61 break; 62 case FUTEX_OP_ADD: 63 __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg); 64 break; 65 case FUTEX_OP_OR: 66 __futex_atomic_op("or %0, %1, %3", ret, oldval, uaddr, oparg); 67 break; 68 case FUTEX_OP_ANDN: 69 __futex_atomic_op("bic %0, %1, %3", ret, oldval, uaddr, oparg); 70 break; 71 case FUTEX_OP_XOR: 72 __futex_atomic_op("xor %0, %1, %3", ret, oldval, uaddr, oparg); 73 break; 74 default: 75 ret = -ENOSYS; 76 } 77 78 pagefault_enable(); /* subsumes preempt_enable() */ 79 80 if (!ret) { 81 switch (cmp) { 82 case FUTEX_OP_CMP_EQ: 83 ret = (oldval == cmparg); 84 break; 85 case FUTEX_OP_CMP_NE: 86 ret = (oldval != cmparg); 87 break; 88 case FUTEX_OP_CMP_LT: 89 ret = (oldval < cmparg); 90 break; 91 case FUTEX_OP_CMP_GE: 92 ret = (oldval >= cmparg); 93 break; 94 case FUTEX_OP_CMP_LE: 95 ret = (oldval <= cmparg); 96 break; 97 case FUTEX_OP_CMP_GT: 98 ret = (oldval > cmparg); 99 break; 100 default: 101 ret = -ENOSYS; 102 } 103 } 104 return ret; 105 } 106 107 /* Compare-xchg with preemption disabled. 108 * Notes: 109 * -Best-Effort: Exchg happens only if compare succeeds. 110 * If compare fails, returns; leaving retry/looping to upper layers 111 * -successful cmp-xchg: return orig value in @addr (same as cmp val) 112 * -Compare fails: return orig value in @addr 113 * -user access r/w fails: return -EFAULT 114 */ 115 static inline int 116 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval, 117 u32 newval) 118 { 119 u32 val; 120 121 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) 122 return -EFAULT; 123 124 pagefault_disable(); /* implies preempt_disable() */ 125 126 /* TBD : can use llock/scond */ 127 __asm__ __volatile__( 128 "1: ld %0, [%3] \n" 129 " brne %0, %1, 3f \n" 130 "2: st %2, [%3] \n" 131 "3: \n" 132 " .section .fixup,\"ax\" \n" 133 "4: mov %0, %4 \n" 134 " b 3b \n" 135 " .previous \n" 136 " .section __ex_table,\"a\" \n" 137 " .align 4 \n" 138 " .word 1b, 4b \n" 139 " .word 2b, 4b \n" 140 " .previous\n" 141 : "=&r"(val) 142 : "r"(oldval), "r"(newval), "r"(uaddr), "ir"(-EFAULT) 143 : "cc", "memory"); 144 145 pagefault_enable(); /* subsumes preempt_enable() */ 146 147 *uval = val; 148 return val; 149 } 150 151 #endif 152