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lib/vdso: Allow fixed clock mode 

Some architectures have a fixed clocksource which is known at compile time
and cannot be replaced or disabled at runtime, e.g. timebase on
PowerPC. For such cases the clock mode check in the VDSO code is pointless.

Move the check for a VDSO capable clocksource into an inline function and
allow architectures to redefine it via a macro.

[ tglx: Removed the #ifdef mess ]

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lkml.kernel.org/r/20200207124403.748756829@linutronix.de
This commit is contained in:
Christophe Leroy 2020-02-07 13:39:02 +01:00 committed by Thomas Gleixner
parent 2d6b01bd88
commit ae12e08539
1 changed files with 9 additions and 2 deletions
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11
lib/vdso/gettimeofday.c
View File

@ -46,6 +46,13 @@ static inline bool __arch_vdso_hres_capable(void)
}
#endif
#ifndef vdso_clocksource_ok
static inline bool vdso_clocksource_ok(const struct vdso_data *vd)
{
return vd->clock_mode != VDSO_CLOCKMODE_NONE;
}
#endif
#ifdef CONFIG_TIME_NS
static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
struct __kernel_timespec *ts)
@ -66,7 +73,7 @@ static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
do {
seq = vdso_read_begin(vd);
if (unlikely(vd->clock_mode == VDSO_CLOCKMODE_NONE))
if (unlikely(!vdso_clocksource_ok(vd)))
return -1;
cycles = __arch_get_hw_counter(vd->clock_mode);
@ -134,7 +141,7 @@ static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
}
smp_rmb();
if (unlikely(vd->clock_mode == VDSO_CLOCKMODE_NONE))
if (unlikely(!vdso_clocksource_ok(vd)))
return -1;
cycles = __arch_get_hw_counter(vd->clock_mode);