arch/arm/include/asm/futex.h

   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         "4:     mov     %0, " err_reg "\n"                      \
  18         "       b       3b\n"                                   \
  19         "       .popsection"
  20
  21 #ifdef CONFIG_SMP
  22
  23 #define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
  24         smp_mb();                                               \
  25         __asm__ __volatile__(                                   \
  26         "1:     ldrex   %1, [%3]\n"                             \
  27         "       " insn "\n"                                     \
  28         "2:     strex   %2, %0, [%3]\n"                         \
  29         "       teq     %2, #0\n"                               \
  30         "       bne     1b\n"                                   \
  31         "       mov     %0, #0\n"                               \
  32         __futex_atomic_ex_table("%5")                           \
  33         : "=&r" (ret), "=&r" (oldval), "=&r" (tmp)              \
  34         : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT)              \
  35         : "cc", "memory")
  36
  37 static inline int
  38 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
  39                               u32 oldval, u32 newval)
  40 {
  41         int ret;
  42         u32 val;
  43
  44         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
  45                 return -EFAULT;
  46
  47         smp_mb();
  48         __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
  49         "1:     ldrex   %1, [%4]\n"
  50         "       teq     %1, %2\n"
  51         "       ite     eq      @ explicit IT needed for the 2b label\n"
  52         "2:     strexeq %0, %3, [%4]\n"
  53         "       movne   %0, #0\n"
  54         "       teq     %0, #0\n"
  55         "       bne     1b\n"
  56         __futex_atomic_ex_table("%5")
  57         : "=&r" (ret), "=&r" (val)
  58         : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
  59         : "cc", "memory");
  60         smp_mb();
  61
  62         *uval = val;
  63         return ret;
  64 }
  65
  66 #else /* !SMP, we can work around lack of atomic ops by disabling preemption */
  67
  68 #include <linux/preempt.h>
  69 #include <asm/domain.h>
  70
  71 #define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
  72         __asm__ __volatile__(                                   \
  73         "1:     " T(ldr) "      %1, [%3]\n"                     \
  74         "       " insn "\n"                                     \
  75         "2:     " T(str) "      %0, [%3]\n"                     \
  76         "       mov     %0, #0\n"                               \
  77         __futex_atomic_ex_table("%5")                           \
  78         : "=&r" (ret), "=&r" (oldval), "=&r" (tmp)              \
  79         : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT)              \
  80         : "cc", "memory")
  81
  82 static inline int
  83 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
  84                               u32 oldval, u32 newval)
  85 {
  86         int ret = 0;
  87         u32 val;
  88
  89         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
  90                 return -EFAULT;
  91
  92         __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
  93         "1:     " T(ldr) "      %1, [%4]\n"
  94         "       teq     %1, %2\n"
  95         "       it      eq      @ explicit IT needed for the 2b label\n"
  96         "2:     " T(streq) "    %3, [%4]\n"
  97         __futex_atomic_ex_table("%5")
  98         : "+r" (ret), "=&r" (val)
  99         : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
 100         : "cc", "memory");
 101
 102         *uval = val;
 103         return ret;
 104 }
 105
 106 #endif /* !SMP */
 107
 108 static inline int
 109 futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
 110 {
 111         int op = (encoded_op >> 28) & 7;
 112         int cmp = (encoded_op >> 24) & 15;
 113         int oparg = (encoded_op << 8) >> 20;
 114         int cmparg = (encoded_op << 20) >> 20;
 115         int oldval = 0, ret, tmp;
 116
 117         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
 118                 oparg = 1 << oparg;
 119
 120         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
 121                 return -EFAULT;
 122
 123         pagefault_disable();    /* implies preempt_disable() */
 124
 125         switch (op) {
 126         case FUTEX_OP_SET:
 127                 __futex_atomic_op("mov  %0, %4", ret, oldval, tmp, uaddr, oparg);
 128                 break;
 129         case FUTEX_OP_ADD:
 130                 __futex_atomic_op("add  %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
 131                 break;
 132         case FUTEX_OP_OR:
 133                 __futex_atomic_op("orr  %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
 134                 break;
 135         case FUTEX_OP_ANDN:
 136                 __futex_atomic_op("and  %0, %1, %4", ret, oldval, tmp, uaddr, ~oparg);
 137                 break;
 138         case FUTEX_OP_XOR:
 139                 __futex_atomic_op("eor  %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
 140                 break;
 141         default:
 142                 ret = -ENOSYS;
 143         }
 144
 145         pagefault_enable();     /* subsumes preempt_enable() */
 146
 147         if (!ret) {
 148                 switch (cmp) {
 149                 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
 150                 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
 151                 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
 152                 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
 153                 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
 154                 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
 155                 default: ret = -ENOSYS;
 156                 }
 157         }
 158         return ret;
 159 }
 160
 161 #endif /* __KERNEL__ */
 162 #endif /* _ASM_ARM_FUTEX_H */