1 #ifndef _ASM_ARM_FUTEX_H 2 #define _ASM_ARM_FUTEX_H 3 4 #ifdef __KERNEL__ 5 6 #include <linux/futex.h> 7 #include <linux/uaccess.h> 8 #include <asm/errno.h> 9 10 #define __futex_atomic_ex_table(err_reg) \ 11 "3:\n" \ 12 " .pushsection __ex_table,\"a\"\n" \ 13 " .align 3\n" \ 14 " .long 1b, 4f, 2b, 4f\n" \ 15 " .popsection\n" \ 16 " .pushsection .fixup,\"ax\"\n" \ 17 " .align 2\n" \ 18 "4: mov %0, " err_reg "\n" \ 19 " b 3b\n" \ 20 " .popsection" 21 22 #ifdef CONFIG_SMP 23 24 #define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \ 25 smp_mb(); \ 26 prefetchw(uaddr); \ 27 __asm__ __volatile__( \ 28 "1: ldrex %1, [%3]\n" \ 29 " " insn "\n" \ 30 "2: strex %2, %0, [%3]\n" \ 31 " teq %2, #0\n" \ 32 " bne 1b\n" \ 33 " mov %0, #0\n" \ 34 __futex_atomic_ex_table("%5") \ 35 : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \ 36 : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \ 37 : "cc", "memory") 38 39 static inline int 40 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, 41 u32 oldval, u32 newval) 42 { 43 int ret; 44 u32 val; 45 46 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))) 47 return -EFAULT; 48 49 smp_mb(); 50 /* Prefetching cannot fault */ 51 prefetchw(uaddr); 52 __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n" 53 "1: ldrex %1, [%4]\n" 54 " teq %1, %2\n" 55 " ite eq @ explicit IT needed for the 2b label\n" 56 "2: strexeq %0, %3, [%4]\n" 57 " movne %0, #0\n" 58 " teq %0, #0\n" 59 " bne 1b\n" 60 __futex_atomic_ex_table("%5") 61 : "=&r" (ret), "=&r" (val) 62 : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT) 63 : "cc", "memory"); 64 smp_mb(); 65 66 *uval = val; 67 return ret; 68 } 69 70 #else /* !SMP, we can work around lack of atomic ops by disabling preemption */ 71 72 #include <linux/preempt.h> 73 #include <asm/domain.h> 74 75 #define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \ 76 __asm__ __volatile__( \ 77 "1: " TUSER(ldr) " %1, [%3]\n" \ 78 " " insn "\n" \ 79 "2: " TUSER(str) " %0, [%3]\n" \ 80 " mov %0, #0\n" \ 81 __futex_atomic_ex_table("%5") \ 82 : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \ 83 : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \ 84 : "cc", "memory") 85 86 static inline int 87 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, 88 u32 oldval, u32 newval) 89 { 90 int ret = 0; 91 u32 val; 92 93 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))) 94 return -EFAULT; 95 96 __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n" 97 "1: " TUSER(ldr) " %1, [%4]\n" 98 " teq %1, %2\n" 99 " it eq @ explicit IT needed for the 2b label\n" 100 "2: " TUSER(streq) " %3, [%4]\n" 101 __futex_atomic_ex_table("%5") 102 : "+r" (ret), "=&r" (val) 103 : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT) 104 : "cc", "memory"); 105 106 *uval = val; 107 return ret; 108 } 109 110 #endif /* !SMP */ 111 112 static inline int 113 futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr) 114 { 115 int op = (encoded_op >> 28) & 7; 116 int cmp = (encoded_op >> 24) & 15; 117 int oparg = (encoded_op << 8) >> 20; 118 int cmparg = (encoded_op << 20) >> 20; 119 int oldval = 0, ret, tmp; 120 121 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) 122 oparg = 1 << oparg; 123 124 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))) 125 return -EFAULT; 126 127 pagefault_disable(); /* implies preempt_disable() */ 128 129 switch (op) { 130 case FUTEX_OP_SET: 131 __futex_atomic_op("mov %0, %4", ret, oldval, tmp, uaddr, oparg); 132 break; 133 case FUTEX_OP_ADD: 134 __futex_atomic_op("add %0, %1, %4", ret, oldval, tmp, uaddr, oparg); 135 break; 136 case FUTEX_OP_OR: 137 __futex_atomic_op("orr %0, %1, %4", ret, oldval, tmp, uaddr, oparg); 138 break; 139 case FUTEX_OP_ANDN: 140 __futex_atomic_op("and %0, %1, %4", ret, oldval, tmp, uaddr, ~oparg); 141 break; 142 case FUTEX_OP_XOR: 143 __futex_atomic_op("eor %0, %1, %4", ret, oldval, tmp, uaddr, oparg); 144 break; 145 default: 146 ret = -ENOSYS; 147 } 148 149 pagefault_enable(); /* subsumes preempt_enable() */ 150 151 if (!ret) { 152 switch (cmp) { 153 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break; 154 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break; 155 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break; 156 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break; 157 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break; 158 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break; 159 default: ret = -ENOSYS; 160 } 161 } 162 return ret; 163 } 164 165 #endif /* __KERNEL__ */ 166 #endif /* _ASM_ARM_FUTEX_H */ 167