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
  13 #define __futex_atomic_op1(insn, ret, oldval, uaddr, oparg)     \
  14         asm volatile("1:\t" insn "\n"                           \
  15                      "2:\t.section .fixup,\"ax\"\n"             \
  16                      "3:\tmov\t%3, %1\n"                        \
  17                      "\tjmp\t2b\n"                              \
  18                      "\t.previous\n"                            \
  19                      _ASM_EXTABLE(1b, 3b)                       \
  20                      : "=r" (oldval), "=r" (ret), "+m" (*uaddr) \
  21                      : "i" (-EFAULT), "0" (oparg), "1" (0))
  22
  23 #define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg)     \
  24         asm volatile("1:\tmovl  %2, %0\n"                       \
  25                      "\tmovl\t%0, %3\n"                         \
  26                      "\t" insn "\n"                             \
  27                      "2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"     \
  28                      "\tjnz\t1b\n"                              \
  29                      "3:\t.section .fixup,\"ax\"\n"             \
  30                      "4:\tmov\t%5, %1\n"                        \
  31                      "\tjmp\t3b\n"                              \
  32                      "\t.previous\n"                            \
  33                      _ASM_EXTABLE(1b, 4b)                       \
  34                      _ASM_EXTABLE(2b, 4b)                       \
  35                      : "=&a" (oldval), "=&r" (ret),             \
  36                        "+m" (*uaddr), "=&r" (tem)               \
  37                      : "r" (oparg), "i" (-EFAULT), "1" (0))
  38
  39 static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
  40 {
  41         int op = (encoded_op >> 28) & 7;
  42         int cmp = (encoded_op >> 24) & 15;
  43         int oparg = (encoded_op << 8) >> 20;
  44         int cmparg = (encoded_op << 20) >> 20;
  45         int oldval = 0, ret, tem;
  46
  47         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  48                 oparg = 1 << oparg;
  49
  50         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
  51                 return -EFAULT;
  52
  53 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_BSWAP)
  54         /* Real i386 machines can only support FUTEX_OP_SET */
  55         if (op != FUTEX_OP_SET && boot_cpu_data.x86 == 3)
  56                 return -ENOSYS;
  57 #endif
  58
  59         pagefault_disable();
  60
  61         switch (op) {
  62         case FUTEX_OP_SET:
  63                 __futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
  64                 break;
  65         case FUTEX_OP_ADD:
  66                 __futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,
  67                                    uaddr, oparg);
  68                 break;
  69         case FUTEX_OP_OR:
  70                 __futex_atomic_op2("orl %4, %3", ret, oldval, uaddr, oparg);
  71                 break;
  72         case FUTEX_OP_ANDN:
  73                 __futex_atomic_op2("andl %4, %3", ret, oldval, uaddr, ~oparg);
  74                 break;
  75         case FUTEX_OP_XOR:
  76                 __futex_atomic_op2("xorl %4, %3", ret, oldval, uaddr, oparg);
  77                 break;
  78         default:
  79                 ret = -ENOSYS;
  80         }
  81
  82         pagefault_enable();
  83
  84         if (!ret) {
  85                 switch (cmp) {
  86                 case FUTEX_OP_CMP_EQ:
  87                         ret = (oldval == cmparg);
  88                         break;
  89                 case FUTEX_OP_CMP_NE:
  90                         ret = (oldval != cmparg);
  91                         break;
  92                 case FUTEX_OP_CMP_LT:
  93                         ret = (oldval < cmparg);
  94                         break;
  95                 case FUTEX_OP_CMP_GE:
  96                         ret = (oldval >= cmparg);
  97                         break;
  98                 case FUTEX_OP_CMP_LE:
  99                         ret = (oldval <= cmparg);
 100                         break;
 101                 case FUTEX_OP_CMP_GT:
 102                         ret = (oldval > cmparg);
 103                         break;
 104                 default:
 105                         ret = -ENOSYS;
 106                 }
 107         }
 108         return ret;
 109 }
 110
 111 static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 112                                                 u32 oldval, u32 newval)
 113 {
 114         int ret = 0;
 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(u32)))
 123                 return -EFAULT;
 124
 125         asm volatile("1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"
 126                      "2:\t.section .fixup, \"ax\"\n"
 127                      "3:\tmov     %3, %0\n"
 128                      "\tjmp     2b\n"
 129                      "\t.previous\n"
 130                      _ASM_EXTABLE(1b, 3b)
 131                      : "+r" (ret), "=a" (oldval), "+m" (*uaddr)
 132                      : "i" (-EFAULT), "r" (newval), "1" (oldval)
 133                      : "memory"
 134         );
 135
 136         *uval = oldval;
 137         return ret;
 138 }
 139
 140 #endif
 141 #endif /* _ASM_X86_FUTEX_H */