1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Copyright (C) 2018 ARM Limited
5 #ifndef __ASM_VDSO_GETTIMEOFDAY_H
6 #define __ASM_VDSO_GETTIMEOFDAY_H
10 #include <asm/unistd.h>
11 #include <uapi/linux/time.h>
13 #include <asm/vdso/clocksource.h>
14 #include <asm/vdso/compat_barrier.h>
16 #define __VDSO_USE_SYSCALL ULLONG_MAX
18 #define VDSO_HAS_CLOCK_GETRES 1
20 #define VDSO_HAS_32BIT_FALLBACK 1
22 static __always_inline
23 int gettimeofday_fallback(struct __kernel_old_timeval *_tv,
26 register struct timezone *tz asm("r1") = _tz;
27 register struct __kernel_old_timeval *tv asm("r0") = _tv;
28 register long ret asm ("r0");
29 register long nr asm("r7") = __NR_compat_gettimeofday;
34 : "r" (tv), "r" (tz), "r" (nr)
40 static __always_inline
41 long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
43 register struct __kernel_timespec *ts asm("r1") = _ts;
44 register clockid_t clkid asm("r0") = _clkid;
45 register long ret asm ("r0");
46 register long nr asm("r7") = __NR_compat_clock_gettime64;
51 : "r" (clkid), "r" (ts), "r" (nr)
57 static __always_inline
58 long clock_gettime32_fallback(clockid_t _clkid, struct old_timespec32 *_ts)
60 register struct old_timespec32 *ts asm("r1") = _ts;
61 register clockid_t clkid asm("r0") = _clkid;
62 register long ret asm ("r0");
63 register long nr asm("r7") = __NR_compat_clock_gettime;
68 : "r" (clkid), "r" (ts), "r" (nr)
74 static __always_inline
75 int clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
77 register struct __kernel_timespec *ts asm("r1") = _ts;
78 register clockid_t clkid asm("r0") = _clkid;
79 register long ret asm ("r0");
80 register long nr asm("r7") = __NR_compat_clock_getres_time64;
82 /* The checks below are required for ABI consistency with arm */
83 if ((_clkid >= MAX_CLOCKS) && (_ts == NULL))
89 : "r" (clkid), "r" (ts), "r" (nr)
95 static __always_inline
96 int clock_getres32_fallback(clockid_t _clkid, struct old_timespec32 *_ts)
98 register struct old_timespec32 *ts asm("r1") = _ts;
99 register clockid_t clkid asm("r0") = _clkid;
100 register long ret asm ("r0");
101 register long nr asm("r7") = __NR_compat_clock_getres;
103 /* The checks below are required for ABI consistency with arm */
104 if ((_clkid >= MAX_CLOCKS) && (_ts == NULL))
110 : "r" (clkid), "r" (ts), "r" (nr)
116 static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
121 * clock_mode == ARCHTIMER implies that vDSO are enabled otherwise
122 * fallback on syscall.
124 if (clock_mode != VDSO_CLOCKMODE_ARCHTIMER)
125 return __VDSO_USE_SYSCALL;
128 * This isb() is required to prevent that the counter value
132 asm volatile("mrrc p15, 1, %Q0, %R0, c14" : "=r" (res));
134 * This isb() is required to prevent that the seq lock is
142 static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
144 const struct vdso_data *ret;
147 * This simply puts &_vdso_data into ret. The reason why we don't use
148 * `ret = _vdso_data` is that the compiler tends to optimise this in a
149 * very suboptimal way: instead of keeping &_vdso_data in a register,
150 * it goes through a relocation almost every time _vdso_data must be
151 * accessed (even in subfunctions). This is both time and space
152 * consuming: each relocation uses a word in the code section, and it
153 * has to be loaded at runtime.
155 * This trick hides the assignment from the compiler. Since it cannot
156 * track where the pointer comes from, it will only use one relocation
157 * where __arch_get_vdso_data() is called, and then keep the result in
160 asm volatile("mov %0, %1" : "=r"(ret) : "r"(_vdso_data));
165 #endif /* !__ASSEMBLY__ */
167 #endif /* __ASM_VDSO_GETTIMEOFDAY_H */