tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
xtensa: implement robust futex atomic uaccess ops
This enables the set_robust_list(2) system call.
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Chris Zankel <chris@zankel.net>
authored by
Baruch Siach
and committed by
Chris Zankel
220c0626
a6e16b9a
+147
-1
-1
arch/xtensa/include/asm/Kbuild
-1
arch/xtensa/include/asm/Kbuild
+147
arch/xtensa/include/asm/futex.h
+147
arch/xtensa/include/asm/futex.h
···
1
+
/*
2
+
* Atomic futex routines
3
+
*
4
+
* Based on the PowerPC implementataion
5
+
*
6
+
* This program is free software; you can redistribute it and/or modify
7
+
* it under the terms of the GNU General Public License version 2 as
8
+
* published by the Free Software Foundation.
9
+
*
10
+
* Copyright (C) 2013 TangoTec Ltd.
11
+
*
12
+
* Baruch Siach <baruch@tkos.co.il>
13
+
*/
14
+
15
+
#ifndef _ASM_XTENSA_FUTEX_H
16
+
#define _ASM_XTENSA_FUTEX_H
17
+
18
+
#ifdef __KERNEL__
19
+
20
+
#include <linux/futex.h>
21
+
#include <linux/uaccess.h>
22
+
#include <linux/errno.h>
23
+
24
+
#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
25
+
__asm__ __volatile( \
26
+
"1: l32i %0, %2, 0\n" \
27
+
insn "\n" \
28
+
" wsr %0, scompare1\n" \
29
+
"2: s32c1i %1, %2, 0\n" \
30
+
" bne %1, %0, 1b\n" \
31
+
" movi %1, 0\n" \
32
+
"3:\n" \
33
+
" .section .fixup,\"ax\"\n" \
34
+
" .align 4\n" \
35
+
"4: .long 3b\n" \
36
+
"5: l32r %0, 4b\n" \
37
+
" movi %1, %3\n" \
38
+
" jx %0\n" \
39
+
" .previous\n" \
40
+
" .section __ex_table,\"a\"\n" \
41
+
" .long 1b,5b,2b,5b\n" \
42
+
" .previous\n" \
43
+
: "=&r" (oldval), "=&r" (ret) \
44
+
: "r" (uaddr), "I" (-EFAULT), "r" (oparg) \
45
+
: "memory")
46
+
47
+
static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
48
+
{
49
+
int op = (encoded_op >> 28) & 7;
50
+
int cmp = (encoded_op >> 24) & 15;
51
+
int oparg = (encoded_op << 8) >> 20;
52
+
int cmparg = (encoded_op << 20) >> 20;
53
+
int oldval = 0, ret;
54
+
if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
55
+
oparg = 1 << oparg;
56
+
57
+
if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
58
+
return -EFAULT;
59
+
60
+
#if !XCHAL_HAVE_S32C1I
61
+
return -ENOSYS;
62
+
#endif
63
+
64
+
pagefault_disable();
65
+
66
+
switch (op) {
67
+
case FUTEX_OP_SET:
68
+
__futex_atomic_op("mov %1, %4", ret, oldval, uaddr, oparg);
69
+
break;
70
+
case FUTEX_OP_ADD:
71
+
__futex_atomic_op("add %1, %0, %4", ret, oldval, uaddr,
72
+
oparg);
73
+
break;
74
+
case FUTEX_OP_OR:
75
+
__futex_atomic_op("or %1, %0, %4", ret, oldval, uaddr,
76
+
oparg);
77
+
break;
78
+
case FUTEX_OP_ANDN:
79
+
__futex_atomic_op("and %1, %0, %4", ret, oldval, uaddr,
80
+
~oparg);
81
+
break;
82
+
case FUTEX_OP_XOR:
83
+
__futex_atomic_op("xor %1, %0, %4", ret, oldval, uaddr,
84
+
oparg);
85
+
break;
86
+
default:
87
+
ret = -ENOSYS;
88
+
}
89
+
90
+
pagefault_enable();
91
+
92
+
if (ret)
93
+
return ret;
94
+
95
+
switch (cmp) {
96
+
case FUTEX_OP_CMP_EQ: return (oldval == cmparg);
97
+
case FUTEX_OP_CMP_NE: return (oldval != cmparg);
98
+
case FUTEX_OP_CMP_LT: return (oldval < cmparg);
99
+
case FUTEX_OP_CMP_GE: return (oldval >= cmparg);
100
+
case FUTEX_OP_CMP_LE: return (oldval <= cmparg);
101
+
case FUTEX_OP_CMP_GT: return (oldval > cmparg);
102
+
}
103
+
104
+
return -ENOSYS;
105
+
}
106
+
107
+
static inline int
108
+
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
109
+
u32 oldval, u32 newval)
110
+
{
111
+
int ret = 0;
112
+
u32 prev;
113
+
114
+
if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
115
+
return -EFAULT;
116
+
117
+
#if !XCHAL_HAVE_S32C1I
118
+
return -ENOSYS;
119
+
#endif
120
+
121
+
__asm__ __volatile__ (
122
+
" # futex_atomic_cmpxchg_inatomic\n"
123
+
"1: l32i %1, %3, 0\n"
124
+
" mov %0, %5\n"
125
+
" wsr %1, scompare1\n"
126
+
"2: s32c1i %0, %3, 0\n"
127
+
"3:\n"
128
+
" .section .fixup,\"ax\"\n"
129
+
" .align 4\n"
130
+
"4: .long 3b\n"
131
+
"5: l32r %1, 4b\n"
132
+
" movi %0, %6\n"
133
+
" jx %1\n"
134
+
" .previous\n"
135
+
" .section __ex_table,\"a\"\n"
136
+
" .long 1b,5b,2b,5b\n"
137
+
" .previous\n"
138
+
: "+r" (ret), "=&r" (prev), "+m" (*uaddr)
139
+
: "r" (uaddr), "r" (oldval), "r" (newval), "I" (-EFAULT)
140
+
: "memory");
141
+
142
+
*uval = prev;
143
+
return ret;
144
+
}
145
+
146
+
#endif /* __KERNEL__ */
147
+
#endif /* _ASM_XTENSA_FUTEX_H */