include/asm-x86/futex.h

   1 #ifndef _ASM_X86_FUTEX_H
   2 #define _ASM_X86_FUTEX_H
   3
   4 #ifdef __KERNEL__
   5
   6 #include <linux/futex.h>
   7
   8 #include <asm/asm.h>
   9 #include <asm/errno.h>
  10 #include <asm/processor.h>
  11 #include <asm/system.h>
  12 #include <asm/uaccess.h>
  13
  14 #define __futex_atomic_op1(insn, ret, oldval, uaddr, oparg)     \
  15   __asm__ __volatile(                                           \
  16 "1:     " insn "\n"                                             \
  17 "2:     .section .fixup,\"ax\"\n                                \
  18 3:      mov     %3, %1\n                                        \
  19         jmp     2b\n                                            \
  20         .previous\n"                                            \
  21         _ASM_EXTABLE(1b,3b)                                     \
  22         : "=r" (oldval), "=r" (ret), "+m" (*uaddr)              \
  23         : "i" (-EFAULT), "0" (oparg), "1" (0))
  24
  25 #define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg)     \
  26   __asm__ __volatile(                                           \
  27 "1:     movl    %2, %0\n                                        \
  28         movl    %0, %3\n"                                       \
  29         insn "\n"                                               \
  30 "2:     lock; cmpxchgl %3, %2\n                                 \
  31         jnz     1b\n                                            \
  32 3:      .section .fixup,\"ax\"\n                                \
  33 4:      mov     %5, %1\n                                        \
  34         jmp     3b\n                                            \
  35         .previous\n"                                            \
  36         _ASM_EXTABLE(1b,4b)                                     \
  37         _ASM_EXTABLE(2b,4b)                                     \
  38         : "=&a" (oldval), "=&r" (ret), "+m" (*uaddr),           \
  39           "=&r" (tem)                                           \
  40         : "r" (oparg), "i" (-EFAULT), "1" (0))
  41
  42 static inline int
  43 futex_atomic_op_inuser(int encoded_op, int __user *uaddr)
  44 {
  45         int op = (encoded_op >> 28) & 7;
  46         int cmp = (encoded_op >> 24) & 15;
  47         int oparg = (encoded_op << 8) >> 20;
  48         int cmparg = (encoded_op << 20) >> 20;
  49         int oldval = 0, ret, tem;
  50
  51         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  52                 oparg = 1 << oparg;
  53
  54         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
  55                 return -EFAULT;
  56
  57 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_BSWAP)
  58         /* Real i386 machines can only support FUTEX_OP_SET */
  59         if (op != FUTEX_OP_SET && boot_cpu_data.x86 == 3)
  60                 return -ENOSYS;
  61 #endif
  62
  63         pagefault_disable();
  64
  65         switch (op) {
  66         case FUTEX_OP_SET:
  67                 __futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
  68                 break;
  69         case FUTEX_OP_ADD:
  70                 __futex_atomic_op1("lock; xaddl %0, %2", ret, oldval,
  71                                    uaddr, oparg);
  72                 break;
  73         case FUTEX_OP_OR:
  74                 __futex_atomic_op2("orl %4, %3", ret, oldval, uaddr, oparg);
  75                 break;
  76         case FUTEX_OP_ANDN:
  77                 __futex_atomic_op2("andl %4, %3", ret, oldval, uaddr, ~oparg);
  78                 break;
  79         case FUTEX_OP_XOR:
  80                 __futex_atomic_op2("xorl %4, %3", ret, oldval, uaddr, oparg);
  81                 break;
  82         default:
  83                 ret = -ENOSYS;
  84         }
  85
  86         pagefault_enable();
  87
  88         if (!ret) {
  89                 switch (cmp) {
  90                 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
  91                 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
  92                 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
  93                 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
  94                 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
  95                 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
  96                 default: ret = -ENOSYS;
  97                 }
  98         }
  99         return ret;
 100 }
 101
 102 static inline int
 103 futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
 104 {
 105
 106 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_BSWAP)
 107         /* Real i386 machines have no cmpxchg instruction */
 108         if (boot_cpu_data.x86 == 3)
 109                 return -ENOSYS;
 110 #endif
 111
 112         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
 113                 return -EFAULT;
 114
 115         __asm__ __volatile__(
 116                 "1:     lock; cmpxchgl %3, %1                   \n"
 117                 "2:     .section .fixup, \"ax\"                 \n"
 118                 "3:     mov     %2, %0                          \n"
 119                 "       jmp     2b                              \n"
 120                 "       .previous                               \n"
 121                 _ASM_EXTABLE(1b,3b)
 122                 : "=a" (oldval), "+m" (*uaddr)
 123                 : "i" (-EFAULT), "r" (newval), "0" (oldval)
 124                 : "memory"
 125         );
 126
 127         return oldval;
 128 }
 129
 130 #endif
 131 #endif