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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2018 ARM Limited
*/
#ifndef __ASM_VDSO_GETTIMEOFDAY_H
#define __ASM_VDSO_GETTIMEOFDAY_H
#ifndef __ASSEMBLY__
#include <asm/unistd.h>
#include <uapi/linux/time.h>
#include <asm/vdso/compat_barrier.h>
#define __VDSO_USE_SYSCALL ULLONG_MAX
#define VDSO_HAS_CLOCK_GETRES 1
static __always_inline
int gettimeofday_fallback(struct __kernel_old_timeval *_tv,
struct timezone *_tz)
{
register struct timezone *tz asm("r1") = _tz;
register struct __kernel_old_timeval *tv asm("r0") = _tv;
register long ret asm ("r0");
register long nr asm("r7") = __NR_compat_gettimeofday;
asm volatile(
" swi #0\n"
: "=r" (ret)
: "r" (tv), "r" (tz), "r" (nr)
: "memory");
return ret;
}
static __always_inline
long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
{
register struct __kernel_timespec *ts asm("r1") = _ts;
register clockid_t clkid asm("r0") = _clkid;
register long ret asm ("r0");
register long nr asm("r7") = __NR_compat_clock_gettime64;
asm volatile(
" swi #0\n"
: "=r" (ret)
: "r" (clkid), "r" (ts), "r" (nr)
: "memory");
return ret;
}
static __always_inline
int clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
{
register struct __kernel_timespec *ts asm("r1") = _ts;
register clockid_t clkid asm("r0") = _clkid;
register long ret asm ("r0");
register long nr asm("r7") = __NR_compat_clock_getres_time64;
/* The checks below are required for ABI consistency with arm */
if ((_clkid >= MAX_CLOCKS) && (_ts == NULL))
return -EINVAL;
asm volatile(
" swi #0\n"
: "=r" (ret)
: "r" (clkid), "r" (ts), "r" (nr)
: "memory");
return ret;
}
static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
{
u64 res;
/*
* clock_mode == 0 implies that vDSO are enabled otherwise
* fallback on syscall.
*/
if (clock_mode)
return __VDSO_USE_SYSCALL;
/*
* This isb() is required to prevent that the counter value
* is speculated.
*/
isb();
asm volatile("mrrc p15, 1, %Q0, %R0, c14" : "=r" (res));
/*
* This isb() is required to prevent that the seq lock is
* speculated.
*/
isb();
return res;
}
static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
{
const struct vdso_data *ret;
/*
* This simply puts &_vdso_data into ret. The reason why we don't use
* `ret = _vdso_data` is that the compiler tends to optimise this in a
* very suboptimal way: instead of keeping &_vdso_data in a register,
* it goes through a relocation almost every time _vdso_data must be
* accessed (even in subfunctions). This is both time and space
* consuming: each relocation uses a word in the code section, and it
* has to be loaded at runtime.
*
* This trick hides the assignment from the compiler. Since it cannot
* track where the pointer comes from, it will only use one relocation
* where __arch_get_vdso_data() is called, and then keep the result in
* a register.
*/
asm volatile("mov %0, %1" : "=r"(ret) : "r"(_vdso_data));
return ret;
}
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_VDSO_GETTIMEOFDAY_H */
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