arch/x86/include/asm/futex.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_X86_FUTEX_H
   3 #define _ASM_X86_FUTEX_H
   4
   5 #ifdef __KERNEL__
   6
   7 #include <linux/futex.h>
   8 #include <linux/uaccess.h>
   9
  10 #include <asm/asm.h>
  11 #include <asm/errno.h>
  12 #include <asm/processor.h>
  13 #include <asm/smap.h>
  14
  15 #define unsafe_atomic_op1(insn, oval, uaddr, oparg, label)      \
  16 do {                                                            \
  17         int oldval = 0, ret;                                    \
  18         asm volatile("1:\t" insn "\n"                           \
  19                      "2:\n"                                     \
  20                      _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAULT_REG, %1) \
  21                      : "=r" (oldval), "=r" (ret), "+m" (*uaddr) \
  22                      : "0" (oparg), "1" (0));   \
  23         if (ret)                                                \
  24                 goto label;                                     \
  25         *oval = oldval;                                         \
  26 } while(0)
  27
  28
  29 #define unsafe_atomic_op2(insn, oval, uaddr, oparg, label)      \
  30 do {                                                            \
  31         int oldval = 0, ret, tem;                               \
  32         asm volatile("1:\tmovl  %2, %0\n"                       \
  33                      "2:\tmovl\t%0, %3\n"                       \
  34                      "\t" insn "\n"                             \
  35                      "3:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"     \
  36                      "\tjnz\t2b\n"                              \
  37                      "4:\n"                                     \
  38                      _ASM_EXTABLE_TYPE_REG(1b, 4b, EX_TYPE_EFAULT_REG, %1) \
  39                      _ASM_EXTABLE_TYPE_REG(3b, 4b, EX_TYPE_EFAULT_REG, %1) \
  40                      : "=&a" (oldval), "=&r" (ret),             \
  41                        "+m" (*uaddr), "=&r" (tem)               \
  42                      : "r" (oparg), "1" (0));                   \
  43         if (ret)                                                \
  44                 goto label;                                     \
  45         *oval = oldval;                                         \
  46 } while(0)
  47
  48 static __always_inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
  49                 u32 __user *uaddr)
  50 {
  51         if (can_do_masked_user_access())
  52                 uaddr = masked_user_access_begin(uaddr);
  53         else if (!user_access_begin(uaddr, sizeof(u32)))
  54                 return -EFAULT;
  55
  56         switch (op) {
  57         case FUTEX_OP_SET:
  58                 unsafe_atomic_op1("xchgl %0, %2", oval, uaddr, oparg, Efault);
  59                 break;
  60         case FUTEX_OP_ADD:
  61                 unsafe_atomic_op1(LOCK_PREFIX "xaddl %0, %2", oval,
  62                                    uaddr, oparg, Efault);
  63                 break;
  64         case FUTEX_OP_OR:
  65                 unsafe_atomic_op2("orl %4, %3", oval, uaddr, oparg, Efault);
  66                 break;
  67         case FUTEX_OP_ANDN:
  68                 unsafe_atomic_op2("andl %4, %3", oval, uaddr, ~oparg, Efault);
  69                 break;
  70         case FUTEX_OP_XOR:
  71                 unsafe_atomic_op2("xorl %4, %3", oval, uaddr, oparg, Efault);
  72                 break;
  73         default:
  74                 user_access_end();
  75                 return -ENOSYS;
  76         }
  77         user_access_end();
  78         return 0;
  79 Efault:
  80         user_access_end();
  81         return -EFAULT;
  82 }
  83
  84 static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
  85                                                 u32 oldval, u32 newval)
  86 {
  87         int ret = 0;
  88
  89         if (can_do_masked_user_access())
  90                 uaddr = masked_user_access_begin(uaddr);
  91         else if (!user_access_begin(uaddr, sizeof(u32)))
  92                 return -EFAULT;
  93         asm volatile("\n"
  94                 "1:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"
  95                 "2:\n"
  96                 _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAULT_REG, %0) \
  97                 : "+r" (ret), "=a" (oldval), "+m" (*uaddr)
  98                 : "r" (newval), "1" (oldval)
  99                 : "memory"
 100         );
 101         user_access_end();
 102         *uval = oldval;
 103         return ret;
 104 }
 105
 106 #endif
 107 #endif /* _ASM_X86_FUTEX_H */