arch/arm/include/asm/futex.h

   1 #ifndef _ASM_ARM_FUTEX_H
   2 #define _ASM_ARM_FUTEX_H
   3
   4 #ifdef __KERNEL__
   5
   6 #ifdef CONFIG_SMP
   7
   8 #include <asm-generic/futex.h>
   9
  10 #else /* !SMP, we can work around lack of atomic ops by disabling preemption */
  11
  12 #include <linux/futex.h>
  13 #include <linux/preempt.h>
  14 #include <linux/uaccess.h>
  15 #include <asm/errno.h>
  16 #include <asm/domain.h>
  17
  18 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)      \
  19         __asm__ __volatile__(                                   \
  20         "1:     " T(ldr) "      %1, [%2]\n"                     \
  21         "       " insn "\n"                                     \
  22         "2:     " T(str) "      %0, [%2]\n"                     \
  23         "       mov     %0, #0\n"                               \
  24         "3:\n"                                                  \
  25         "       .pushsection __ex_table,\"a\"\n"                \
  26         "       .align  3\n"                                    \
  27         "       .long   1b, 4f, 2b, 4f\n"                       \
  28         "       .popsection\n"                                  \
  29         "       .pushsection .fixup,\"ax\"\n"                   \
  30         "4:     mov     %0, %4\n"                               \
  31         "       b       3b\n"                                   \
  32         "       .popsection"                                    \
  33         : "=&r" (ret), "=&r" (oldval)                           \
  34         : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT)              \
  35         : "cc", "memory")
  36
  37 static inline int
  38 futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
  39 {
  40         int op = (encoded_op >> 28) & 7;
  41         int cmp = (encoded_op >> 24) & 15;
  42         int oparg = (encoded_op << 8) >> 20;
  43         int cmparg = (encoded_op << 20) >> 20;
  44         int oldval = 0, ret;
  45
  46         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  47                 oparg = 1 << oparg;
  48
  49         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
  50                 return -EFAULT;
  51
  52         pagefault_disable();    /* implies preempt_disable() */
  53
  54         switch (op) {
  55         case FUTEX_OP_SET:
  56                 __futex_atomic_op("mov  %0, %3", ret, oldval, uaddr, oparg);
  57                 break;
  58         case FUTEX_OP_ADD:
  59                 __futex_atomic_op("add  %0, %1, %3", ret, oldval, uaddr, oparg);
  60                 break;
  61         case FUTEX_OP_OR:
  62                 __futex_atomic_op("orr  %0, %1, %3", ret, oldval, uaddr, oparg);
  63                 break;
  64         case FUTEX_OP_ANDN:
  65                 __futex_atomic_op("and  %0, %1, %3", ret, oldval, uaddr, ~oparg);
  66                 break;
  67         case FUTEX_OP_XOR:
  68                 __futex_atomic_op("eor  %0, %1, %3", ret, oldval, uaddr, oparg);
  69                 break;
  70         default:
  71                 ret = -ENOSYS;
  72         }
  73
  74         pagefault_enable();     /* subsumes preempt_enable() */
  75
  76         if (!ret) {
  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 static inline int
  91 futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
  92 {
  93         int val;
  94
  95         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
  96                 return -EFAULT;
  97
  98         pagefault_disable();    /* implies preempt_disable() */
  99
 100         __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
 101         "1:     " T(ldr) "      %0, [%3]\n"
 102         "       teq     %0, %1\n"
 103         "       it      eq      @ explicit IT needed for the 2b label\n"
 104         "2:     " T(streq) "    %2, [%3]\n"
 105         "3:\n"
 106         "       .pushsection __ex_table,\"a\"\n"
 107         "       .align  3\n"
 108         "       .long   1b, 4f, 2b, 4f\n"
 109         "       .popsection\n"
 110         "       .pushsection .fixup,\"ax\"\n"
 111         "4:     mov     %0, %4\n"
 112         "       b       3b\n"
 113         "       .popsection"
 114         : "=&r" (val)
 115         : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
 116         : "cc", "memory");
 117
 118         pagefault_enable();     /* subsumes preempt_enable() */
 119
 120         return val;
 121 }
 122
 123 #endif /* !SMP */
 124
 125 #endif /* __KERNEL__ */
 126 #endif /* _ASM_ARM_FUTEX_H */