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         "       .align  2\n"                                    \
  23         "4:     mov     %0, " err_reg "\n"                      \
  24         "       b       3b\n"                                   \
  25         "       .popsection"
  26
  27 #ifdef CONFIG_SMP
  28
  29 #define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
  30         smp_mb();                                               \
  31         __asm__ __volatile__(                                   \
  32         "1:     ldrex   %1, [%3]\n"                             \
  33         "       " insn "\n"                                     \
  34         "2:     strex   %2, %0, [%3]\n"                         \
  35         "       teq     %2, #0\n"                               \
  36         "       bne     1b\n"                                   \
  37         "       mov     %0, #0\n"                               \
  38         __futex_atomic_ex_table("%5")                           \
  39         : "=&r" (ret), "=&r" (oldval), "=&r" (tmp)              \
  40         : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT)              \
  41         : "cc", "memory")
  42
  43 static inline int
  44 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
  45                               u32 oldval, u32 newval)
  46 {
  47         int ret;
  48         u32 val;
  49
  50         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
  51                 return -EFAULT;
  52
  53         smp_mb();
  54         __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
  55         "1:     ldrex   %1, [%4]\n"
  56         "       teq     %1, %2\n"
  57         "       ite     eq      @ explicit IT needed for the 2b label\n"
  58         "2:     strexeq %0, %3, [%4]\n"
  59         "       movne   %0, #0\n"
  60         "       teq     %0, #0\n"
  61         "       bne     1b\n"
  62         __futex_atomic_ex_table("%5")
  63         : "=&r" (ret), "=&r" (val)
  64         : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
  65         : "cc", "memory");
  66         smp_mb();
  67
  68         *uval = val;
  69         return ret;
  70 }
  71
  72 #else /* !SMP, we can work around lack of atomic ops by disabling preemption */
  73
  74 #include <linux/preempt.h>
  75 #include <asm/domain.h>
  76
  77 #define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
  78         __asm__ __volatile__(                                   \
  79         "1:     " TUSER(ldr) "  %1, [%3]\n"                     \
  80         "       " insn "\n"                                     \
  81         "2:     " TUSER(str) "  %0, [%3]\n"                     \
  82         "       mov     %0, #0\n"                               \
  83         __futex_atomic_ex_table("%5")                           \
  84         : "=&r" (ret), "=&r" (oldval), "=&r" (tmp)              \
  85         : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT)              \
  86         : "cc", "memory")
  87
  88 static inline int
  89 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
  90                               u32 oldval, u32 newval)
  91 {
  92         int ret = 0;
  93         u32 val;
  94
  95         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
  96                 return -EFAULT;
  97
  98         __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
  99         "1:     " TUSER(ldr) "  %1, [%4]\n"
 100         "       teq     %1, %2\n"
 101         "       it      eq      @ explicit IT needed for the 2b label\n"
 102         "2:     " TUSER(streq) "        %3, [%4]\n"
 103         __futex_atomic_ex_table("%5")
 104         : "+r" (ret), "=&r" (val)
 105         : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
 106         : "cc", "memory");
 107
 108         *uval = val;
 109         return ret;
 110 }
 111
 112 #endif /* !SMP */
 113
 114 static inline int
 115 futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
 116 {
 117         int op = (encoded_op >> 28) & 7;
 118         int cmp = (encoded_op >> 24) & 15;
 119         int oparg = (encoded_op << 8) >> 20;
 120         int cmparg = (encoded_op << 20) >> 20;
 121         int oldval = 0, ret, tmp;
 122
 123         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
 124                 oparg = 1 << oparg;
 125
 126         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
 127                 return -EFAULT;
 128
 129         pagefault_disable();    /* implies preempt_disable() */
 130
 131         switch (op) {
 132         case FUTEX_OP_SET:
 133                 __futex_atomic_op("mov  %0, %4", ret, oldval, tmp, uaddr, oparg);
 134                 break;
 135         case FUTEX_OP_ADD:
 136                 __futex_atomic_op("add  %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
 137                 break;
 138         case FUTEX_OP_OR:
 139                 __futex_atomic_op("orr  %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
 140                 break;
 141         case FUTEX_OP_ANDN:
 142                 __futex_atomic_op("and  %0, %1, %4", ret, oldval, tmp, uaddr, ~oparg);
 143                 break;
 144         case FUTEX_OP_XOR:
 145                 __futex_atomic_op("eor  %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
 146                 break;
 147         default:
 148                 ret = -ENOSYS;
 149         }
 150
 151         pagefault_enable();     /* subsumes preempt_enable() */
 152
 153         if (!ret) {
 154                 switch (cmp) {
 155                 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
 156                 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
 157                 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
 158                 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
 159                 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
 160                 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
 161                 default: ret = -ENOSYS;
 162                 }
 163         }
 164         return ret;
 165 }
 166
 167 #endif /* !(CPU_USE_DOMAINS && SMP) */
 168 #endif /* __KERNEL__ */
 169 #endif /* _ASM_ARM_FUTEX_H */