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
  17 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)      \
  18         __asm__ __volatile__(                                   \
  19         "1:     ldrt    %1, [%2]\n"                             \
  20         "       " insn "\n"                                     \
  21         "2:     strt    %0, [%2]\n"                             \
  22         "       mov     %0, #0\n"                               \
  23         "3:\n"                                                  \
  24         "       .pushsection __ex_table,\"a\"\n"                \
  25         "       .align  3\n"                                    \
  26         "       .long   1b, 4f, 2b, 4f\n"                       \
  27         "       .popsection\n"                                  \
  28         "       .pushsection .fixup,\"ax\"\n"                   \
  29         "4:     mov     %0, %4\n"                               \
  30         "       b       3b\n"                                   \
  31         "       .popsection"                                    \
  32         : "=&r" (ret), "=&r" (oldval)                           \
  33         : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT)              \
  34         : "cc", "memory")
  35
  36 static inline int
  37 futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
  38 {
  39         int op = (encoded_op >> 28) & 7;
  40         int cmp = (encoded_op >> 24) & 15;
  41         int oparg = (encoded_op << 8) >> 20;
  42         int cmparg = (encoded_op << 20) >> 20;
  43         int oldval = 0, ret;
  44
  45         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  46                 oparg = 1 << oparg;
  47
  48         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
  49                 return -EFAULT;
  50
  51         pagefault_disable();    /* implies preempt_disable() */
  52
  53         switch (op) {
  54         case FUTEX_OP_SET:
  55                 __futex_atomic_op("mov  %0, %3", ret, oldval, uaddr, oparg);
  56                 break;
  57         case FUTEX_OP_ADD:
  58                 __futex_atomic_op("add  %0, %1, %3", ret, oldval, uaddr, oparg);
  59                 break;
  60         case FUTEX_OP_OR:
  61                 __futex_atomic_op("orr  %0, %1, %3", ret, oldval, uaddr, oparg);
  62                 break;
  63         case FUTEX_OP_ANDN:
  64                 __futex_atomic_op("and  %0, %1, %3", ret, oldval, uaddr, ~oparg);
  65                 break;
  66         case FUTEX_OP_XOR:
  67                 __futex_atomic_op("eor  %0, %1, %3", ret, oldval, uaddr, oparg);
  68                 break;
  69         default:
  70                 ret = -ENOSYS;
  71         }
  72
  73         pagefault_enable();     /* subsumes preempt_enable() */
  74
  75         if (!ret) {
  76                 switch (cmp) {
  77                 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
  78                 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
  79                 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
  80                 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
  81                 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
  82                 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
  83                 default: ret = -ENOSYS;
  84                 }
  85         }
  86         return ret;
  87 }
  88
  89 static inline int
  90 futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
  91 {
  92         int val;
  93
  94         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
  95                 return -EFAULT;
  96
  97         pagefault_disable();    /* implies preempt_disable() */
  98
  99         __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
 100         "1:     ldrt    %0, [%3]\n"
 101         "       teq     %0, %1\n"
 102         "       it      eq      @ explicit IT needed for the 2b label\n"
 103         "2:     streqt  %2, [%3]\n"
 104         "3:\n"
 105         "       .pushsection __ex_table,\"a\"\n"
 106         "       .align  3\n"
 107         "       .long   1b, 4f, 2b, 4f\n"
 108         "       .popsection\n"
 109         "       .pushsection .fixup,\"ax\"\n"
 110         "4:     mov     %0, %4\n"
 111         "       b       3b\n"
 112         "       .popsection"
 113         : "=&r" (val)
 114         : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
 115         : "cc", "memory");
 116
 117         pagefault_enable();     /* subsumes preempt_enable() */
 118
 119         return val;
 120 }
 121
 122 #endif /* !SMP */
 123
 124 #endif /* __KERNEL__ */
 125 #endif /* _ASM_ARM_FUTEX_H */