arch/x86/include/asm/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 #include <linux/uaccess.h>
   8
   9 #include <asm/asm.h>
  10 #include <asm/errno.h>
  11 #include <asm/processor.h>
  12 #include <asm/system.h>
  13
  14 #define __futex_atomic_op1(insn, ret, oldval, uaddr, oparg)     \
  15         asm volatile("1:\t" insn "\n"                           \
  16                      "2:\t.section .fixup,\"ax\"\n"             \
  17                      "3:\tmov\t%3, %1\n"                        \
  18                      "\tjmp\t2b\n"                              \
  19                      "\t.previous\n"                            \
  20                      _ASM_EXTABLE(1b, 3b)                       \
  21                      : "=r" (oldval), "=r" (ret), "+m" (*uaddr) \
  22                      : "i" (-EFAULT), "0" (oparg), "1" (0))
  23
  24 #define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg)     \
  25         asm volatile("1:\tmovl  %2, %0\n"                       \
  26                      "\tmovl\t%0, %3\n"                         \
  27                      "\t" insn "\n"                             \
  28                      "2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"     \
  29                      "\tjnz\t1b\n"                              \
  30                      "3:\t.section .fixup,\"ax\"\n"             \
  31                      "4:\tmov\t%5, %1\n"                        \
  32                      "\tjmp\t3b\n"                              \
  33                      "\t.previous\n"                            \
  34                      _ASM_EXTABLE(1b, 4b)                       \
  35                      _ASM_EXTABLE(2b, 4b)                       \
  36                      : "=&a" (oldval), "=&r" (ret),             \
  37                        "+m" (*uaddr), "=&r" (tem)               \
  38                      : "r" (oparg), "i" (-EFAULT), "1" (0))
  39
  40 static inline int futex_atomic_op_inuser(int encoded_op, int __user *uaddr)
  41 {
  42         int op = (encoded_op >> 28) & 7;
  43         int cmp = (encoded_op >> 24) & 15;
  44         int oparg = (encoded_op << 8) >> 20;
  45         int cmparg = (encoded_op << 20) >> 20;
  46         int oldval = 0, ret, tem;
  47
  48         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  49                 oparg = 1 << oparg;
  50
  51         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
  52                 return -EFAULT;
  53
  54 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_BSWAP)
  55         /* Real i386 machines can only support FUTEX_OP_SET */
  56         if (op != FUTEX_OP_SET && boot_cpu_data.x86 == 3)
  57                 return -ENOSYS;
  58 #endif
  59
  60         pagefault_disable();
  61
  62         switch (op) {
  63         case FUTEX_OP_SET:
  64                 __futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
  65                 break;
  66         case FUTEX_OP_ADD:
  67                 __futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,
  68                                    uaddr, oparg);
  69                 break;
  70         case FUTEX_OP_OR:
  71                 __futex_atomic_op2("orl %4, %3", ret, oldval, uaddr, oparg);
  72                 break;
  73         case FUTEX_OP_ANDN:
  74                 __futex_atomic_op2("andl %4, %3", ret, oldval, uaddr, ~oparg);
  75                 break;
  76         case FUTEX_OP_XOR:
  77                 __futex_atomic_op2("xorl %4, %3", ret, oldval, uaddr, oparg);
  78                 break;
  79         default:
  80                 ret = -ENOSYS;
  81         }
  82
  83         pagefault_enable();
  84
  85         if (!ret) {
  86                 switch (cmp) {
  87                 case FUTEX_OP_CMP_EQ:
  88                         ret = (oldval == cmparg);
  89                         break;
  90                 case FUTEX_OP_CMP_NE:
  91                         ret = (oldval != cmparg);
  92                         break;
  93                 case FUTEX_OP_CMP_LT:
  94                         ret = (oldval < cmparg);
  95                         break;
  96                 case FUTEX_OP_CMP_GE:
  97                         ret = (oldval >= cmparg);
  98                         break;
  99                 case FUTEX_OP_CMP_LE:
 100                         ret = (oldval <= cmparg);
 101                         break;
 102                 case FUTEX_OP_CMP_GT:
 103                         ret = (oldval > cmparg);
 104                         break;
 105                 default:
 106                         ret = -ENOSYS;
 107                 }
 108         }
 109         return ret;
 110 }
 111
 112 static inline int futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval,
 113                                                 int newval)
 114 {
 115
 116 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_BSWAP)
 117         /* Real i386 machines have no cmpxchg instruction */
 118         if (boot_cpu_data.x86 == 3)
 119                 return -ENOSYS;
 120 #endif
 121
 122         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
 123                 return -EFAULT;
 124
 125         asm volatile("1:\t" LOCK_PREFIX "cmpxchgl %3, %1\n"
 126                      "2:\t.section .fixup, \"ax\"\n"
 127                      "3:\tmov     %2, %0\n"
 128                      "\tjmp     2b\n"
 129                      "\t.previous\n"
 130                      _ASM_EXTABLE(1b, 3b)
 131                      : "=a" (oldval), "+m" (*uaddr)
 132                      : "i" (-EFAULT), "r" (newval), "0" (oldval)
 133                      : "memory"
 134         );
 135
 136         return oldval;
 137 }
 138
 139 #endif
 140 #endif /* _ASM_X86_FUTEX_H */