include/asm/futex.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 #ifndef _ASM_X86_FUTEX_H
0003 #define _ASM_X86_FUTEX_H
0004
0005 #ifdef __KERNEL__
0006
0007 #include <linux/futex.h>
0008 #include <linux/uaccess.h>
0009
0010 #include <asm/asm.h>
0011 #include <asm/errno.h>
0012 #include <asm/processor.h>
0013 #include <asm/smap.h>
0014
0015 #define unsafe_atomic_op1(insn, oval, uaddr, oparg, label)  \
0016 do {                                \
0017     int oldval = 0, ret;                    \
0018     asm volatile("1:\t" insn "\n"               \
0019              "2:\n"                 \
0020              _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAULT_REG, %1) \
0021              : "=r" (oldval), "=r" (ret), "+m" (*uaddr) \
0022              : "0" (oparg), "1" (0));   \
0023     if (ret)                        \
0024         goto label;                 \
0025     *oval = oldval;                     \
0026 } while(0)
0027
0028
0029 #define unsafe_atomic_op2(insn, oval, uaddr, oparg, label)  \
0030 do {                                \
0031     int oldval = 0, ret, tem;               \
0032     asm volatile("1:\tmovl  %2, %0\n"           \
0033              "2:\tmovl\t%0, %3\n"           \
0034              "\t" insn "\n"             \
0035              "3:\t" LOCK_PREFIX "cmpxchgl %3, %2\n" \
0036              "\tjnz\t2b\n"              \
0037              "4:\n"                 \
0038              _ASM_EXTABLE_TYPE_REG(1b, 4b, EX_TYPE_EFAULT_REG, %1) \
0039              _ASM_EXTABLE_TYPE_REG(3b, 4b, EX_TYPE_EFAULT_REG, %1) \
0040              : "=&a" (oldval), "=&r" (ret),     \
0041                "+m" (*uaddr), "=&r" (tem)       \
0042              : "r" (oparg), "1" (0));           \
0043     if (ret)                        \
0044         goto label;                 \
0045     *oval = oldval;                     \
0046 } while(0)
0047
0048 static __always_inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
0049         u32 __user *uaddr)
0050 {
0051     if (!user_access_begin(uaddr, sizeof(u32)))
0052         return -EFAULT;
0053
0054     switch (op) {
0055     case FUTEX_OP_SET:
0056         unsafe_atomic_op1("xchgl %0, %2", oval, uaddr, oparg, Efault);
0057         break;
0058     case FUTEX_OP_ADD:
0059         unsafe_atomic_op1(LOCK_PREFIX "xaddl %0, %2", oval,
0060                    uaddr, oparg, Efault);
0061         break;
0062     case FUTEX_OP_OR:
0063         unsafe_atomic_op2("orl %4, %3", oval, uaddr, oparg, Efault);
0064         break;
0065     case FUTEX_OP_ANDN:
0066         unsafe_atomic_op2("andl %4, %3", oval, uaddr, ~oparg, Efault);
0067         break;
0068     case FUTEX_OP_XOR:
0069         unsafe_atomic_op2("xorl %4, %3", oval, uaddr, oparg, Efault);
0070         break;
0071     default:
0072         user_access_end();
0073         return -ENOSYS;
0074     }
0075     user_access_end();
0076     return 0;
0077 Efault:
0078     user_access_end();
0079     return -EFAULT;
0080 }
0081
0082 static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
0083                         u32 oldval, u32 newval)
0084 {
0085     int ret = 0;
0086
0087     if (!user_access_begin(uaddr, sizeof(u32)))
0088         return -EFAULT;
0089     asm volatile("\n"
0090         "1:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"
0091         "2:\n"
0092         _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAULT_REG, %0) \
0093         : "+r" (ret), "=a" (oldval), "+m" (*uaddr)
0094         : "r" (newval), "1" (oldval)
0095         : "memory"
0096     );
0097     user_access_end();
0098     *uval = oldval;
0099     return ret;
0100 }
0101
0102 #endif
0103 #endif /* _ASM_X86_FUTEX_H */