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         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 */