arch/arm/include/asm/futex.h

   1 #ifndef _ASM_ARM_FUTEX_H
   2 #define _ASM_ARM_FUTEX_H
   3
   4 #ifdef __KERNEL__
   5
   6 #if defined(CONFIG_CPU_USE_DOMAINS) && defined(CONFIG_SMP)
   7 /* ARM doesn't provide unprivileged exclusive memory accessors */
   8 #include <asm-generic/futex.h>
   9 #else
  10
  11 #include <linux/futex.h>
  12 #include <linux/uaccess.h>
  13 #include <asm/errno.h>
  14
  15 #define __futex_atomic_ex_table(err_reg)                        \
  16         "3:\n"                                                  \
  17         "       .pushsection __ex_table,\"a\"\n"                \
  18         "       .align  3\n"                                    \
  19         "       .long   1b, 4f, 2b, 4f\n"                       \
  20         "       .popsection\n"                                  \
  21         "       .pushsection .fixup,\"ax\"\n"                   \
  22         "4:     mov     %0, " err_reg "\n"                      \
  23         "       b       3b\n"                                   \
  24         "       .popsection"
  25
  26 #ifdef CONFIG_SMP
  27
  28 #define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
  29         smp_mb();                                               \
  30         __asm__ __volatile__(                                   \
  31         "1:     ldrex   %1, [%3]\n"                             \
  32         "       " insn "\n"                                     \
  33         "2:     strex   %2, %0, [%3]\n"                         \
  34         "       teq     %2, #0\n"                               \
  35         "       bne     1b\n"                                   \
  36         "       mov     %0, #0\n"                               \
  37         __futex_atomic_ex_table("%5")                           \
  38         : "=&r" (ret), "=&r" (oldval), "=&r" (tmp)              \
  39         : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT)              \
  40         : "cc", "memory")
  41
  42 static inline int
  43 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
  44                               u32 oldval, u32 newval)
  45 {
  46         int ret;
  47         u32 val;
  48
  49         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
  50                 return -EFAULT;
  51
  52         smp_mb();
  53         __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
  54         "1:     ldrex   %1, [%4]\n"
  55         "       teq     %1, %2\n"
  56         "       ite     eq      @ explicit IT needed for the 2b label\n"
  57         "2:     strexeq %0, %3, [%4]\n"
  58         "       movne   %0, #0\n"
  59         "       teq     %0, #0\n"
  60         "       bne     1b\n"
  61         __futex_atomic_ex_table("%5")
  62         : "=&r" (ret), "=&r" (val)
  63         : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
  64         : "cc", "memory");
  65         smp_mb();
  66
  67         *uval = val;
  68         return ret;
  69 }
  70
  71 #else /* !SMP, we can work around lack of atomic ops by disabling preemption */
  72
  73 #include <linux/preempt.h>
  74 #include <asm/domain.h>
  75
  76 #define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
  77         __asm__ __volatile__(                                   \
  78         "1:     " TUSER(ldr) "  %1, [%3]\n"                     \
  79         "       " insn "\n"                                     \
  80         "2:     " TUSER(str) "  %0, [%3]\n"                     \
  81         "       mov     %0, #0\n"                               \
  82         __futex_atomic_ex_table("%5")                           \
  83         : "=&r" (ret), "=&r" (oldval), "=&r" (tmp)              \
  84         : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT)              \
  85         : "cc", "memory")
  86
  87 static inline int
  88 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
  89                               u32 oldval, u32 newval)
  90 {
  91         int ret = 0;
  92         u32 val;
  93
  94         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
  95                 return -EFAULT;
  96
  97         __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
  98         "1:     " TUSER(ldr) "  %1, [%4]\n"
  99         "       teq     %1, %2\n"
 100         "       it      eq      @ explicit IT needed for the 2b label\n"
 101         "2:     " TUSER(streq) "        %3, [%4]\n"
 102         __futex_atomic_ex_table("%5")
 103         : "+r" (ret), "=&r" (val)
 104         : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
 105         : "cc", "memory");
 106
 107         *uval = val;
 108         return ret;
 109 }
 110
 111 #endif /* !SMP */
 112
 113 static inline int
 114 futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
 115 {
 116         int op = (encoded_op >> 28) & 7;
 117         int cmp = (encoded_op >> 24) & 15;
 118         int oparg = (encoded_op << 8) >> 20;
 119         int cmparg = (encoded_op << 20) >> 20;
 120         int oldval = 0, ret, tmp;
 121
 122         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
 123                 oparg = 1 << oparg;
 124
 125         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
 126                 return -EFAULT;
 127
 128         pagefault_disable();    /* implies preempt_disable() */
 129
 130         switch (op) {
 131         case FUTEX_OP_SET:
 132                 __futex_atomic_op("mov  %0, %4", ret, oldval, tmp, uaddr, oparg);
 133                 break;
 134         case FUTEX_OP_ADD:
 135                 __futex_atomic_op("add  %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
 136                 break;
 137         case FUTEX_OP_OR:
 138                 __futex_atomic_op("orr  %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
 139                 break;
 140         case FUTEX_OP_ANDN:
 141                 __futex_atomic_op("and  %0, %1, %4", ret, oldval, tmp, uaddr, ~oparg);
 142                 break;
 143         case FUTEX_OP_XOR:
 144                 __futex_atomic_op("eor  %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
 145                 break;
 146         default:
 147                 ret = -ENOSYS;
 148         }
 149
 150         pagefault_enable();     /* subsumes preempt_enable() */
 151
 152         if (!ret) {
 153                 switch (cmp) {
 154                 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
 155                 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
 156                 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
 157                 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
 158                 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
 159                 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
 160                 default: ret = -ENOSYS;
 161                 }
 162         }
 163         return ret;
 164 }
 165
 166 #endif /* !(CPU_USE_DOMAINS && SMP) */
 167 #endif /* __KERNEL__ */
 168 #endif /* _ASM_ARM_FUTEX_H */