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