1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Copyright (C) 2018 ARM Limited
4 */
5#ifndef __ASM_VDSO_GETTIMEOFDAY_H
6#define __ASM_VDSO_GETTIMEOFDAY_H
7
8#ifndef __ASSEMBLY__
9
10#include <asm/barrier.h>
11#include <asm/unistd.h>
12#include <asm/errno.h>
13
14#include <asm/vdso/compat_barrier.h>
15
16#define VDSO_HAS_CLOCK_GETRES		1
17
18#define BUILD_VDSO32			1
19
20static __always_inline
21int gettimeofday_fallback(struct __kernel_old_timeval *_tv,
22			  struct timezone *_tz)
23{
24	register struct timezone *tz asm("r1") = _tz;
25	register struct __kernel_old_timeval *tv asm("r0") = _tv;
26	register long ret asm ("r0");
27	register long nr asm("r7") = __NR_compat_gettimeofday;
28
29	asm volatile(
30	"	swi #0\n"
31	: "=r" (ret)
32	: "r" (tv), "r" (tz), "r" (nr)
33	: "memory");
34
35	return ret;
36}
37
38static __always_inline
39long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
40{
41	register struct __kernel_timespec *ts asm("r1") = _ts;
42	register clockid_t clkid asm("r0") = _clkid;
43	register long ret asm ("r0");
44	register long nr asm("r7") = __NR_compat_clock_gettime64;
45
46	asm volatile(
47	"	swi #0\n"
48	: "=r" (ret)
49	: "r" (clkid), "r" (ts), "r" (nr)
50	: "memory");
51
52	return ret;
53}
54
55static __always_inline
56long clock_gettime32_fallback(clockid_t _clkid, struct old_timespec32 *_ts)
57{
58	register struct old_timespec32 *ts asm("r1") = _ts;
59	register clockid_t clkid asm("r0") = _clkid;
60	register long ret asm ("r0");
61	register long nr asm("r7") = __NR_compat_clock_gettime;
62
63	asm volatile(
64	"	swi #0\n"
65	: "=r" (ret)
66	: "r" (clkid), "r" (ts), "r" (nr)
67	: "memory");
68
69	return ret;
70}
71
72static __always_inline
73int clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
74{
75	register struct __kernel_timespec *ts asm("r1") = _ts;
76	register clockid_t clkid asm("r0") = _clkid;
77	register long ret asm ("r0");
78	register long nr asm("r7") = __NR_compat_clock_getres_time64;
79
80	asm volatile(
81	"       swi #0\n"
82	: "=r" (ret)
83	: "r" (clkid), "r" (ts), "r" (nr)
84	: "memory");
85
86	return ret;
87}
88
89static __always_inline
90int clock_getres32_fallback(clockid_t _clkid, struct old_timespec32 *_ts)
91{
92	register struct old_timespec32 *ts asm("r1") = _ts;
93	register clockid_t clkid asm("r0") = _clkid;
94	register long ret asm ("r0");
95	register long nr asm("r7") = __NR_compat_clock_getres;
96
97	asm volatile(
98	"       swi #0\n"
99	: "=r" (ret)
100	: "r" (clkid), "r" (ts), "r" (nr)
101	: "memory");
102
103	return ret;
104}
105
106static __always_inline u64 __arch_get_hw_counter(s32 clock_mode,
107						 const struct vdso_data *vd)
108{
109	u64 res;
110
111	/*
112	 * Core checks for mode already, so this raced against a concurrent
113	 * update. Return something. Core will do another round and then
114	 * see the mode change and fallback to the syscall.
115	 */
116	if (clock_mode != VDSO_CLOCKMODE_ARCHTIMER)
117		return 0;
118
119	/*
120	 * This isb() is required to prevent that the counter value
121	 * is speculated.
122	 */
123	isb();
124	asm volatile("mrrc p15, 1, %Q0, %R0, c14" : "=r" (res));
125	/*
126	 * This isb() is required to prevent that the seq lock is
127	 * speculated.
128	 */
129	isb();
130
131	return res;
132}
133
134static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
135{
136	const struct vdso_data *ret;
137
138	/*
139	 * This simply puts &_vdso_data into ret. The reason why we don't use
140	 * `ret = _vdso_data` is that the compiler tends to optimise this in a
141	 * very suboptimal way: instead of keeping &_vdso_data in a register,
142	 * it goes through a relocation almost every time _vdso_data must be
143	 * accessed (even in subfunctions). This is both time and space
144	 * consuming: each relocation uses a word in the code section, and it
145	 * has to be loaded at runtime.
146	 *
147	 * This trick hides the assignment from the compiler. Since it cannot
148	 * track where the pointer comes from, it will only use one relocation
149	 * where __arch_get_vdso_data() is called, and then keep the result in
150	 * a register.
151	 */
152	asm volatile("mov %0, %1" : "=r"(ret) : "r"(_vdso_data));
153
154	return ret;
155}
156
157#ifdef CONFIG_TIME_NS
158static __always_inline
159const struct vdso_data *__arch_get_timens_vdso_data(const struct vdso_data *vd)
160{
161	const struct vdso_data *ret;
162
163	/* See __arch_get_vdso_data(). */
164	asm volatile("mov %0, %1" : "=r"(ret) : "r"(_timens_data));
165
166	return ret;
167}
168#endif
169
170static inline bool vdso_clocksource_ok(const struct vdso_data *vd)
171{
172	return vd->clock_mode == VDSO_CLOCKMODE_ARCHTIMER;
173}
174#define vdso_clocksource_ok	vdso_clocksource_ok
175
176#endif /* !__ASSEMBLY__ */
177
178#endif /* __ASM_VDSO_GETTIMEOFDAY_H */
179