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 __futex_atomic_op1(insn, ret, oldval, uaddr, oparg)     \
  16         asm volatile("\t" ASM_STAC "\n"                         \
  17                      "1:\t" insn "\n"                           \
  18                      "2:\t" ASM_CLAC "\n"                       \
  19                      "\t.section .fixup,\"ax\"\n"               \
  20                      "3:\tmov\t%3, %1\n"                        \
  21                      "\tjmp\t2b\n"                              \
  22                      "\t.previous\n"                            \
  23                      _ASM_EXTABLE(1b, 3b)                       \
  24                      : "=r" (oldval), "=r" (ret), "+m" (*uaddr) \
  25                      : "i" (-EFAULT), "0" (oparg), "1" (0))
  26
  27 #define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg)     \
  28         asm volatile("\t" ASM_STAC "\n"                         \
  29                      "1:\tmovl  %2, %0\n"                       \
  30                      "\tmovl\t%0, %3\n"                         \
  31                      "\t" insn "\n"                             \
  32                      "2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"     \
  33                      "\tjnz\t1b\n"                              \
  34                      "3:\t" ASM_CLAC "\n"                       \
  35                      "\t.section .fixup,\"ax\"\n"               \
  36                      "4:\tmov\t%5, %1\n"                        \
  37                      "\tjmp\t3b\n"                              \
  38                      "\t.previous\n"                            \
  39                      _ASM_EXTABLE(1b, 4b)                       \
  40                      _ASM_EXTABLE(2b, 4b)                       \
  41                      : "=&a" (oldval), "=&r" (ret),             \
  42                        "+m" (*uaddr), "=&r" (tem)               \
  43                      : "r" (oparg), "i" (-EFAULT), "1" (0))
  44
  45 static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
  46                 u32 __user *uaddr)
  47 {
  48         int oldval = 0, ret, tem;
  49
  50         pagefault_disable();
  51
  52         switch (op) {
  53         case FUTEX_OP_SET:
  54                 __futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
  55                 break;
  56         case FUTEX_OP_ADD:
  57                 __futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,
  58                                    uaddr, oparg);
  59                 break;
  60         case FUTEX_OP_OR:
  61                 __futex_atomic_op2("orl %4, %3", ret, oldval, uaddr, oparg);
  62                 break;
  63         case FUTEX_OP_ANDN:
  64                 __futex_atomic_op2("andl %4, %3", ret, oldval, uaddr, ~oparg);
  65                 break;
  66         case FUTEX_OP_XOR:
  67                 __futex_atomic_op2("xorl %4, %3", ret, oldval, uaddr, oparg);
  68                 break;
  69         default:
  70                 ret = -ENOSYS;
  71         }
  72
  73         pagefault_enable();
  74
  75         if (!ret)
  76                 *oval = oldval;
  77
  78         return ret;
  79 }
  80
  81 static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
  82                                                 u32 oldval, u32 newval)
  83 {
  84         return user_atomic_cmpxchg_inatomic(uval, uaddr, oldval, newval);
  85 }
  86
  87 #endif
  88 #endif /* _ASM_X86_FUTEX_H */