LXR linux/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
  43static inline int
  44futex_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
  88static inline int
  89futex_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
 114static inline int
 115futex_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 */
 170