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         .section __ex_table,\"a\"\n                             \
  22         .align  8\n"                                            \
  23         _ASM_PTR "1b,3b\n                                       \
  24         .previous"                                              \
  25         : "=r" (oldval), "=r" (ret), "+m" (*uaddr)              \
  26         : "i" (-EFAULT), "0" (oparg), "1" (0))
  27
  28 #define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg)     \
  29   __asm__ __volatile(                                           \
  30 "1:     movl    %2, %0\n                                        \
  31         movl    %0, %3\n"                                       \
  32         insn "\n"                                               \
  33 "2:     " LOCK_PREFIX "cmpxchgl %3, %2\n                        \
  34         jnz     1b\n                                            \
  35 3:      .section .fixup,\"ax\"\n                                \
  36 4:      mov     %5, %1\n                                        \
  37         jmp     3b\n                                            \
  38         .previous\n                                             \
  39         .section __ex_table,\"a\"\n                             \
  40         .align  8\n"                                            \
  41         _ASM_PTR "1b,4b,2b,4b\n                                 \
  42         .previous"                                              \
  43         : "=&a" (oldval), "=&r" (ret), "+m" (*uaddr),           \
  44           "=&r" (tem)                                           \
  45         : "r" (oparg), "i" (-EFAULT), "1" (0))
  46
  47 static inline int
  48 futex_atomic_op_inuser(int encoded_op, int __user *uaddr)
  49 {
  50         int op = (encoded_op >> 28) & 7;
  51         int cmp = (encoded_op >> 24) & 15;
  52         int oparg = (encoded_op << 8) >> 20;
  53         int cmparg = (encoded_op << 20) >> 20;
  54         int oldval = 0, ret, tem;
  55
  56         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  57                 oparg = 1 << oparg;
  58
  59         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
  60                 return -EFAULT;
  61
  62 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_BSWAP)
  63         /* Real i386 machines can only support FUTEX_OP_SET */
  64         if (op != FUTEX_OP_SET && boot_cpu_data.x86 == 3)
  65                 return -ENOSYS;
  66 #endif
  67
  68         pagefault_disable();
  69
  70         switch (op) {
  71         case FUTEX_OP_SET:
  72                 __futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
  73                 break;
  74         case FUTEX_OP_ADD:
  75                 __futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,
  76                                    uaddr, oparg);
  77                 break;
  78         case FUTEX_OP_OR:
  79                 __futex_atomic_op2("orl %4, %3", ret, oldval, uaddr, oparg);
  80                 break;
  81         case FUTEX_OP_ANDN:
  82                 __futex_atomic_op2("andl %4, %3", ret, oldval, uaddr, ~oparg);
  83                 break;
  84         case FUTEX_OP_XOR:
  85                 __futex_atomic_op2("xorl %4, %3", ret, oldval, uaddr, oparg);
  86                 break;
  87         default:
  88                 ret = -ENOSYS;
  89         }
  90
  91         pagefault_enable();
  92
  93         if (!ret) {
  94                 switch (cmp) {
  95                 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
  96                 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
  97                 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
  98                 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
  99                 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
 100                 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
 101                 default: ret = -ENOSYS;
 102                 }
 103         }
 104         return ret;
 105 }
 106
 107 static inline int
 108 futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
 109 {
 110         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
 111                 return -EFAULT;
 112
 113         __asm__ __volatile__(
 114                 "1:     " LOCK_PREFIX "cmpxchgl %3, %1          \n"
 115
 116                 "2:     .section .fixup, \"ax\"                 \n"
 117                 "3:     mov     %2, %0                          \n"
 118                 "       jmp     2b                              \n"
 119                 "       .previous                               \n"
 120
 121                 "       .section __ex_table, \"a\"              \n"
 122                 "       .align  8                               \n"
 123                         _ASM_PTR " 1b,3b                        \n"
 124                 "       .previous                               \n"
 125
 126                 : "=a" (oldval), "+m" (*uaddr)
 127                 : "i" (-EFAULT), "r" (newval), "0" (oldval)
 128                 : "memory"
 129         );
 130
 131         return oldval;
 132 }
 133
 134 #endif
 135 #endif