aboutsummaryrefslogtreecommitdiffstats
path: root/include/asm-x86/futex.h
blob: 9d919264923a0b12db0bd804abed465c5ce82c55 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
#ifndef _ASM_X86_FUTEX_H
#define _ASM_X86_FUTEX_H

#ifdef __KERNEL__

#include <linux/futex.h>

#include <asm/asm.h>
#include <asm/errno.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/uaccess.h>

#define __futex_atomic_op1(insn, ret, oldval, uaddr, oparg)	\
  __asm__ __volatile(						\
"1:	" insn "\n"						\
"2:	.section .fixup,\"ax\"\n				\
3:	mov	%3, %1\n					\
	jmp	2b\n						\
	.previous\n						\
	.section __ex_table,\"a\"\n				\
	.align	8\n"						\
	_ASM_PTR "1b,3b\n					\
	.previous"						\
	: "=r" (oldval), "=r" (ret), "+m" (*uaddr)		\
	: "i" (-EFAULT), "0" (oparg), "1" (0))

#define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg)	\
  __asm__ __volatile(						\
"1:	movl	%2, %0\n					\
	movl	%0, %3\n"					\
	insn "\n"						\
"2:	lock; cmpxchgl %3, %2\n					\
	jnz	1b\n						\
3:	.section .fixup,\"ax\"\n				\
4:	mov	%5, %1\n					\
	jmp	3b\n						\
	.previous\n						\
	.section __ex_table,\"a\"\n				\
	.align	8\n"						\
	_ASM_PTR "1b,4b,2b,4b\n					\
	.previous"						\
	: "=&a" (oldval), "=&r" (ret), "+m" (*uaddr),		\
	  "=&r" (tem)						\
	: "r" (oparg), "i" (-EFAULT), "1" (0))

static inline int
futex_atomic_op_inuser(int encoded_op, int __user *uaddr)
{
	int op = (encoded_op >> 28) & 7;
	int cmp = (encoded_op >> 24) & 15;
	int oparg = (encoded_op << 8) >> 20;
	int cmparg = (encoded_op << 20) >> 20;
	int oldval = 0, ret, tem;

	if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
		oparg = 1 << oparg;

	if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
		return -EFAULT;

#if defined(CONFIG_X86_32) && !defined(CONFIG_X86_BSWAP)
	/* Real i386 machines can only support FUTEX_OP_SET */
	if (op != FUTEX_OP_SET && boot_cpu_data.x86 == 3)
		return -ENOSYS;
#endif

	pagefault_disable();

	switch (op) {
	case FUTEX_OP_SET:
		__futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
		break;
	case FUTEX_OP_ADD:
		__futex_atomic_op1("lock; xaddl %0, %2", ret, oldval,
				   uaddr, oparg);
		break;
	case FUTEX_OP_OR:
		__futex_atomic_op2("orl %4, %3", ret, oldval, uaddr, oparg);
		break;
	case FUTEX_OP_ANDN:
		__futex_atomic_op2("andl %4, %3", ret, oldval, uaddr, ~oparg);
		break;
	case FUTEX_OP_XOR:
		__futex_atomic_op2("xorl %4, %3", ret, oldval, uaddr, oparg);
		break;
	default:
		ret = -ENOSYS;
	}

	pagefault_enable();

	if (!ret) {
		switch (cmp) {
		case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
		case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
		case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
		case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
		case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
		case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
		default: ret = -ENOSYS;
		}
	}
	return ret;
}

static inline int
futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
{
	if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
		return -EFAULT;

	__asm__ __volatile__(

		"1:	lock; cmpxchgl %3, %1			\n"
		"2:	.section .fixup, \"ax\"			\n"
		"3:	mov     %2, %0				\n"
		"	jmp     2b				\n"
		"	.previous				\n"

		"	.section __ex_table, \"a\"		\n"
		"	.align  8				\n"
			_ASM_PTR " 1b,3b			\n"
		"	.previous				\n"

		: "=a" (oldval), "+m" (*uaddr)
		: "i" (-EFAULT), "r" (newval), "0" (oldval)
		: "memory"
	);

	return oldval;
}

#endif
#endif