1 #ifndef _ASM_GENERIC_FUTEX_H 2 #define _ASM_GENERIC_FUTEX_H 3 4 #include <linux/futex.h> 5 #include <linux/uaccess.h> 6 #include <asm/errno.h> 7 8 #ifndef CONFIG_SMP 9 /* 10 * The following implementation only for uniprocessor machines. 11 * It relies on preempt_disable() ensuring mutual exclusion. 12 * 13 */ 14 15 /** 16 * futex_atomic_op_inuser() - Atomic arithmetic operation with constant 17 * argument and comparison of the previous 18 * futex value with another constant. 19 * 20 * @encoded_op: encoded operation to execute 21 * @uaddr: pointer to user space address 22 * 23 * Return: 24 * 0 - On success 25 * <0 - On error 26 */ 27 static inline int 28 futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr) 29 { 30 int op = (encoded_op >> 28) & 7; 31 int cmp = (encoded_op >> 24) & 15; 32 int oparg = (encoded_op << 8) >> 20; 33 int cmparg = (encoded_op << 20) >> 20; 34 int oldval, ret; 35 u32 tmp; 36 37 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) 38 oparg = 1 << oparg; 39 40 preempt_disable(); 41 pagefault_disable(); 42 43 ret = -EFAULT; 44 if (unlikely(get_user(oldval, uaddr) != 0)) 45 goto out_pagefault_enable; 46 47 ret = 0; 48 tmp = oldval; 49 50 switch (op) { 51 case FUTEX_OP_SET: 52 tmp = oparg; 53 break; 54 case FUTEX_OP_ADD: 55 tmp += oparg; 56 break; 57 case FUTEX_OP_OR: 58 tmp |= oparg; 59 break; 60 case FUTEX_OP_ANDN: 61 tmp &= ~oparg; 62 break; 63 case FUTEX_OP_XOR: 64 tmp ^= oparg; 65 break; 66 default: 67 ret = -ENOSYS; 68 } 69 70 if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0)) 71 ret = -EFAULT; 72 73 out_pagefault_enable: 74 pagefault_enable(); 75 preempt_enable(); 76 77 if (ret == 0) { 78 switch (cmp) { 79 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break; 80 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break; 81 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break; 82 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break; 83 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break; 84 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break; 85 default: ret = -ENOSYS; 86 } 87 } 88 return ret; 89 } 90 91 /** 92 * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the 93 * uaddr with newval if the current value is 94 * oldval. 95 * @uval: pointer to store content of @uaddr 96 * @uaddr: pointer to user space address 97 * @oldval: old value 98 * @newval: new value to store to @uaddr 99 * 100 * Return: 101 * 0 - On success 102 * <0 - On error 103 */ 104 static inline int 105 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, 106 u32 oldval, u32 newval) 107 { 108 u32 val; 109 110 preempt_disable(); 111 if (unlikely(get_user(val, uaddr) != 0)) 112 return -EFAULT; 113 114 if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) 115 return -EFAULT; 116 117 *uval = val; 118 preempt_enable(); 119 120 return 0; 121 } 122 123 #else 124 static inline int 125 futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr) 126 { 127 int op = (encoded_op >> 28) & 7; 128 int cmp = (encoded_op >> 24) & 15; 129 int oparg = (encoded_op << 8) >> 20; 130 int cmparg = (encoded_op << 20) >> 20; 131 int oldval = 0, ret; 132 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) 133 oparg = 1 << oparg; 134 135 if (! access_ok (VERIFY_WRITE, uaddr, sizeof(u32))) 136 return -EFAULT; 137 138 pagefault_disable(); 139 140 switch (op) { 141 case FUTEX_OP_SET: 142 case FUTEX_OP_ADD: 143 case FUTEX_OP_OR: 144 case FUTEX_OP_ANDN: 145 case FUTEX_OP_XOR: 146 default: 147 ret = -ENOSYS; 148 } 149 150 pagefault_enable(); 151 152 if (!ret) { 153 switch (cmp) { 154 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break; 155 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break; 156 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break; 157 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break; 158 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break; 159 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break; 160 default: ret = -ENOSYS; 161 } 162 } 163 return ret; 164 } 165 166 static inline int 167 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, 168 u32 oldval, u32 newval) 169 { 170 return -ENOSYS; 171 } 172 173 #endif /* CONFIG_SMP */ 174 #endif 175