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 * For UP, it's relies on the fact that pagefault_disable() also disables 12 * preemption to ensure mutual exclusion. 13 * 14 */ 15 16 /** 17 * futex_atomic_op_inuser() - Atomic arithmetic operation with constant 18 * argument and comparison of the previous 19 * futex value with another constant. 20 * 21 * @encoded_op: encoded operation to execute 22 * @uaddr: pointer to user space address 23 * 24 * Return: 25 * 0 - On success 26 * <0 - On error 27 */ 28 static inline int 29 futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr) 30 { 31 int op = (encoded_op >> 28) & 7; 32 int cmp = (encoded_op >> 24) & 15; 33 int oparg = (encoded_op << 8) >> 20; 34 int cmparg = (encoded_op << 20) >> 20; 35 int oldval, ret; 36 u32 tmp; 37 38 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) 39 oparg = 1 << oparg; 40 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 76 if (ret == 0) { 77 switch (cmp) { 78 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break; 79 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break; 80 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break; 81 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break; 82 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break; 83 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break; 84 default: ret = -ENOSYS; 85 } 86 } 87 return ret; 88 } 89 90 /** 91 * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the 92 * uaddr with newval if the current value is 93 * oldval. 94 * @uval: pointer to store content of @uaddr 95 * @uaddr: pointer to user space address 96 * @oldval: old value 97 * @newval: new value to store to @uaddr 98 * 99 * Return: 100 * 0 - On success 101 * <0 - On error 102 */ 103 static inline int 104 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, 105 u32 oldval, u32 newval) 106 { 107 u32 val; 108 109 if (unlikely(get_user(val, uaddr) != 0)) 110 return -EFAULT; 111 112 if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) 113 return -EFAULT; 114 115 *uval = val; 116 117 return 0; 118 } 119 120 #else 121 static inline int 122 futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr) 123 { 124 int op = (encoded_op >> 28) & 7; 125 int cmp = (encoded_op >> 24) & 15; 126 int oparg = (encoded_op << 8) >> 20; 127 int cmparg = (encoded_op << 20) >> 20; 128 int oldval = 0, ret; 129 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) 130 oparg = 1 << oparg; 131 132 if (! access_ok (VERIFY_WRITE, uaddr, sizeof(u32))) 133 return -EFAULT; 134 135 pagefault_disable(); 136 137 switch (op) { 138 case FUTEX_OP_SET: 139 case FUTEX_OP_ADD: 140 case FUTEX_OP_OR: 141 case FUTEX_OP_ANDN: 142 case FUTEX_OP_XOR: 143 default: 144 ret = -ENOSYS; 145 } 146 147 pagefault_enable(); 148 149 if (!ret) { 150 switch (cmp) { 151 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break; 152 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break; 153 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break; 154 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break; 155 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break; 156 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break; 157 default: ret = -ENOSYS; 158 } 159 } 160 return ret; 161 } 162 163 static inline int 164 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, 165 u32 oldval, u32 newval) 166 { 167 return -ENOSYS; 168 } 169 170 #endif /* CONFIG_SMP */ 171 #endif 172