tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Copyright (C) 2012 ARM Ltd.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program. If not, see <http://www.gnu.org/licenses/>.
15 */
16#ifndef __ASM_FUTEX_H
17#define __ASM_FUTEX_H
18
19#ifdef __KERNEL__
20
21#include <linux/futex.h>
22#include <linux/uaccess.h>
23
24#include <asm/alternative.h>
25#include <asm/cpufeature.h>
26#include <asm/errno.h>
27#include <asm/sysreg.h>
28
29#define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg) \
30 asm volatile( \
31 ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \
32 CONFIG_ARM64_PAN) \
33" prfm pstl1strm, %2\n" \
34"1: ldxr %w1, %2\n" \
35 insn "\n" \
36"2: stlxr %w3, %w0, %2\n" \
37" cbnz %w3, 1b\n" \
38" dmb ish\n" \
39"3:\n" \
40" .pushsection .fixup,\"ax\"\n" \
41" .align 2\n" \
42"4: mov %w0, %w5\n" \
43" b 3b\n" \
44" .popsection\n" \
45 _ASM_EXTABLE(1b, 4b) \
46 _ASM_EXTABLE(2b, 4b) \
47 ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, \
48 CONFIG_ARM64_PAN) \
49 : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp) \
50 : "r" (oparg), "Ir" (-EFAULT) \
51 : "memory")
52
53static inline int
54futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
55{
56 int op = (encoded_op >> 28) & 7;
57 int cmp = (encoded_op >> 24) & 15;
58 int oparg = (encoded_op << 8) >> 20;
59 int cmparg = (encoded_op << 20) >> 20;
60 int oldval = 0, ret, tmp;
61
62 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
63 oparg = 1 << oparg;
64
65 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
66 return -EFAULT;
67
68 pagefault_disable();
69
70 switch (op) {
71 case FUTEX_OP_SET:
72 __futex_atomic_op("mov %w0, %w4",
73 ret, oldval, uaddr, tmp, oparg);
74 break;
75 case FUTEX_OP_ADD:
76 __futex_atomic_op("add %w0, %w1, %w4",
77 ret, oldval, uaddr, tmp, oparg);
78 break;
79 case FUTEX_OP_OR:
80 __futex_atomic_op("orr %w0, %w1, %w4",
81 ret, oldval, uaddr, tmp, oparg);
82 break;
83 case FUTEX_OP_ANDN:
84 __futex_atomic_op("and %w0, %w1, %w4",
85 ret, oldval, uaddr, tmp, ~oparg);
86 break;
87 case FUTEX_OP_XOR:
88 __futex_atomic_op("eor %w0, %w1, %w4",
89 ret, oldval, uaddr, tmp, oparg);
90 break;
91 default:
92 ret = -ENOSYS;
93 }
94
95 pagefault_enable();
96
97 if (!ret) {
98 switch (cmp) {
99 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
100 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
101 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
102 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
103 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
104 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
105 default: ret = -ENOSYS;
106 }
107 }
108 return ret;
109}
110
111static inline int
112futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
113 u32 oldval, u32 newval)
114{
115 int ret = 0;
116 u32 val, tmp;
117
118 if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
119 return -EFAULT;
120
121 asm volatile("// futex_atomic_cmpxchg_inatomic\n"
122ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
123" prfm pstl1strm, %2\n"
124"1: ldxr %w1, %2\n"
125" sub %w3, %w1, %w4\n"
126" cbnz %w3, 3f\n"
127"2: stlxr %w3, %w5, %2\n"
128" cbnz %w3, 1b\n"
129" dmb ish\n"
130"3:\n"
131" .pushsection .fixup,\"ax\"\n"
132"4: mov %w0, %w6\n"
133" b 3b\n"
134" .popsection\n"
135 _ASM_EXTABLE(1b, 4b)
136 _ASM_EXTABLE(2b, 4b)
137ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
138 : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp)
139 : "r" (oldval), "r" (newval), "Ir" (-EFAULT)
140 : "memory");
141
142 *uval = val;
143 return ret;
144}
145
146#endif /* __KERNEL__ */
147#endif /* __ASM_FUTEX_H */