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 .text.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 ({                                                              \
  26         unsigned int __ua_flags;                                \
  27         smp_mb();                                               \
  28         prefetchw(uaddr);                                       \
  29         __ua_flags = uaccess_save_and_enable();                 \
  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         uaccess_restore(__ua_flags);                            \
  42 })
  43
  44 static inline int
  45 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
  46                               u32 oldval, u32 newval)
  47 {
  48         unsigned int __ua_flags;
  49         int ret;
  50         u32 val;
  51
  52         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
  53                 return -EFAULT;
  54
  55         smp_mb();
  56         /* Prefetching cannot fault */
  57         prefetchw(uaddr);
  58         __ua_flags = uaccess_save_and_enable();
  59         __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
  60         "1:     ldrex   %1, [%4]\n"
  61         "       teq     %1, %2\n"
  62         "       ite     eq      @ explicit IT needed for the 2b label\n"
  63         "2:     strexeq %0, %3, [%4]\n"
  64         "       movne   %0, #0\n"
  65         "       teq     %0, #0\n"
  66         "       bne     1b\n"
  67         __futex_atomic_ex_table("%5")
  68         : "=&r" (ret), "=&r" (val)
  69         : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
  70         : "cc", "memory");
  71         uaccess_restore(__ua_flags);
  72         smp_mb();
  73
  74         *uval = val;
  75         return ret;
  76 }
  77
  78 #else /* !SMP, we can work around lack of atomic ops by disabling preemption */
  79
  80 #include <linux/preempt.h>
  81 #include <asm/domain.h>
  82
  83 #define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
  84 ({                                                              \
  85         unsigned int __ua_flags = uaccess_save_and_enable();    \
  86         __asm__ __volatile__(                                   \
  87         "1:     " TUSER(ldr) "  %1, [%3]\n"                     \
  88         "       " insn "\n"                                     \
  89         "2:     " TUSER(str) "  %0, [%3]\n"                     \
  90         "       mov     %0, #0\n"                               \
  91         __futex_atomic_ex_table("%5")                           \
  92         : "=&r" (ret), "=&r" (oldval), "=&r" (tmp)              \
  93         : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT)              \
  94         : "cc", "memory");                                      \
  95         uaccess_restore(__ua_flags);                            \
  96 })
  97
  98 static inline int
  99 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 100                               u32 oldval, u32 newval)
 101 {
 102         unsigned int __ua_flags;
 103         int ret = 0;
 104         u32 val;
 105
 106         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
 107                 return -EFAULT;
 108
 109         preempt_disable();
 110         __ua_flags = uaccess_save_and_enable();
 111         __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
 112         "1:     " TUSER(ldr) "  %1, [%4]\n"
 113         "       teq     %1, %2\n"
 114         "       it      eq      @ explicit IT needed for the 2b label\n"
 115         "2:     " TUSER(streq) "        %3, [%4]\n"
 116         __futex_atomic_ex_table("%5")
 117         : "+r" (ret), "=&r" (val)
 118         : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
 119         : "cc", "memory");
 120         uaccess_restore(__ua_flags);
 121
 122         *uval = val;
 123         preempt_enable();
 124
 125         return ret;
 126 }
 127
 128 #endif /* !SMP */
 129
 130 static inline int
 131 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 132 {
 133         int oldval = 0, ret, tmp;
 134
 135 #ifndef CONFIG_SMP
 136         preempt_disable();
 137 #endif
 138         pagefault_disable();
 139
 140         switch (op) {
 141         case FUTEX_OP_SET:
 142                 __futex_atomic_op("mov  %0, %4", ret, oldval, tmp, uaddr, oparg);
 143                 break;
 144         case FUTEX_OP_ADD:
 145                 __futex_atomic_op("add  %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
 146                 break;
 147         case FUTEX_OP_OR:
 148                 __futex_atomic_op("orr  %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
 149                 break;
 150         case FUTEX_OP_ANDN:
 151                 __futex_atomic_op("and  %0, %1, %4", ret, oldval, tmp, uaddr, ~oparg);
 152                 break;
 153         case FUTEX_OP_XOR:
 154                 __futex_atomic_op("eor  %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
 155                 break;
 156         default:
 157                 ret = -ENOSYS;
 158         }
 159
 160         pagefault_enable();
 161 #ifndef CONFIG_SMP
 162         preempt_enable();
 163 #endif
 164
 165         if (!ret)
 166                 *oval = oldval;
 167
 168         return ret;
 169 }
 170
 171 #endif /* __KERNEL__ */
 172 #endif /* _ASM_ARM_FUTEX_H */