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 */ 108