127 lines
3 KiB
C
127 lines
3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2018 ARM Limited
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*/
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#ifndef __ASM_VDSO_GETTIMEOFDAY_H
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#define __ASM_VDSO_GETTIMEOFDAY_H
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#ifndef __ASSEMBLY__
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#include <asm/unistd.h>
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#include <asm/errno.h>
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#include <asm/vdso/compat_barrier.h>
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#define __VDSO_USE_SYSCALL ULLONG_MAX
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#define VDSO_HAS_CLOCK_GETRES 1
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#define VDSO_HAS_TIME 1
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#define BUILD_VDSO32 1
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static __always_inline
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int gettimeofday_fallback(struct __kernel_old_timeval *_tv,
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struct timezone *_tz)
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{
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register struct timezone *tz asm("r1") = _tz;
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register struct __kernel_old_timeval *tv asm("r0") = _tv;
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register long ret asm ("r0");
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register long nr asm("r7") = __NR_compat_gettimeofday;
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asm volatile(
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" swi #0\n"
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: "=r" (ret)
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: "r" (tv), "r" (tz), "r" (nr)
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: "memory");
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return ret;
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}
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static __always_inline
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long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
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{
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register struct __kernel_timespec *ts asm("r1") = _ts;
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register clockid_t clkid asm("r0") = _clkid;
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register long ret asm ("r0");
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register long nr asm("r7") = __NR_compat_clock_gettime;
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asm volatile(
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" swi #0\n"
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: "=r" (ret)
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: "r" (clkid), "r" (ts), "r" (nr)
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: "memory");
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return ret;
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}
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static __always_inline
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int clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
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{
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register struct __kernel_timespec *ts asm("r1") = _ts;
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register clockid_t clkid asm("r0") = _clkid;
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register long ret asm ("r0");
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register long nr asm("r7") = __NR_compat_clock_getres;
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asm volatile(
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" swi #0\n"
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: "=r" (ret)
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: "r" (clkid), "r" (ts), "r" (nr)
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: "memory");
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return ret;
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}
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static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
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{
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u64 res;
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/*
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* clock_mode == 0 implies that vDSO are enabled otherwise
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* fallback on syscall.
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*/
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if (clock_mode)
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return __VDSO_USE_SYSCALL;
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/*
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* This isb() is required to prevent that the counter value
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* is speculated.
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*/
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isb();
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asm volatile("mrrc p15, 1, %Q0, %R0, c14" : "=r" (res));
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/*
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* This isb() is required to prevent that the seq lock is
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* speculated.
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*/
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isb();
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return res;
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}
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static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
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{
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const struct vdso_data *ret;
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/*
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* This simply puts &_vdso_data into ret. The reason why we don't use
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* `ret = _vdso_data` is that the compiler tends to optimise this in a
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* very suboptimal way: instead of keeping &_vdso_data in a register,
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* it goes through a relocation almost every time _vdso_data must be
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* accessed (even in subfunctions). This is both time and space
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* consuming: each relocation uses a word in the code section, and it
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* has to be loaded at runtime.
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*
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* This trick hides the assignment from the compiler. Since it cannot
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* track where the pointer comes from, it will only use one relocation
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* where __arch_get_vdso_data() is called, and then keep the result in
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* a register.
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*/
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asm volatile("mov %0, %1" : "=r"(ret) : "r"(_vdso_data));
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return ret;
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}
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#endif /* !__ASSEMBLY__ */
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#endif /* __ASM_VDSO_GETTIMEOFDAY_H */
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