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clocksource: Add common vdso clock mode storage 

All architectures which use the generic VDSO code have their own storage
for the VDSO clock mode. That's pointless and just requires duplicate code.

Provide generic storage for it. The new Kconfig symbol is intermediate and
will be removed once all architectures are converted over.

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/20200207124403.028046322@linutronix.de
This commit is contained in:
Thomas Gleixner 2020-02-07 13:38:55 +01:00
parent eec399dd86
commit 5d51bee725
5 changed files with 42 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
include/linux/clocksource.h
View File

@ -23,10 +23,19 @@
struct clocksource;
struct module;
#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
#if defined(CONFIG_ARCH_CLOCKSOURCE_DATA) || \
defined(CONFIG_GENERIC_VDSO_CLOCK_MODE)
#include <asm/clocksource.h>
#endif
enum vdso_clock_mode {
VDSO_CLOCKMODE_NONE,
#ifdef CONFIG_GENERIC_VDSO_CLOCK_MODE
VDSO_ARCH_CLOCKMODES,
#endif
VDSO_CLOCKMODE_MAX,
};
/**
* struct clocksource - hardware abstraction for a free running counter
* Provides mostly state-free accessors to the underlying hardware.
@ -97,6 +106,7 @@ struct clocksource {
const char *name;
struct list_head list;
int rating;
enum vdso_clock_mode vdso_clock_mode;
unsigned long flags;
int (*enable)(struct clocksource *cs);

9
kernel/time/clocksource.c
View File

@ -928,6 +928,15 @@ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)
clocksource_arch_init(cs);
#ifdef CONFIG_GENERIC_VDSO_CLOCK_MODE
if (cs->vdso_clock_mode < 0 ||
cs->vdso_clock_mode >= VDSO_CLOCKMODE_MAX) {
pr_warn("clocksource %s registered with invalid VDSO mode %d. Disabling VDSO support.\n",
cs->name, cs->vdso_clock_mode);
cs->vdso_clock_mode = VDSO_CLOCKMODE_NONE;
}
#endif
/* Initialize mult/shift and max_idle_ns */
__clocksource_update_freq_scale(cs, scale, freq);

10
kernel/time/vsyscall.c
View File

@ -71,13 +71,19 @@ void update_vsyscall(struct timekeeper *tk)
{
struct vdso_data *vdata = __arch_get_k_vdso_data();
struct vdso_timestamp *vdso_ts;
s32 clock_mode;
u64 nsec;
/* copy vsyscall data */
vdso_write_begin(vdata);
vdata[CS_HRES_COARSE].clock_mode = __arch_get_clock_mode(tk);
vdata[CS_RAW].clock_mode = __arch_get_clock_mode(tk);
#ifdef CONFIG_GENERIC_VDSO_CLOCK_MODE
clock_mode = tk->tkr_mono.clock->vdso_clock_mode;
#else
clock_mode = __arch_get_clock_mode(tk);
#endif
vdata[CS_HRES_COARSE].clock_mode = clock_mode;
vdata[CS_RAW].clock_mode = clock_mode;
/* CLOCK_REALTIME also required for time() */
vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME];

3
lib/vdso/Kconfig
View File

@ -30,4 +30,7 @@ config GENERIC_VDSO_TIME_NS
Selected by architectures which support time namespaces in the
VDSO
config GENERIC_VDSO_CLOCK_MODE
bool
endif

13
lib/vdso/gettimeofday.c
View File

@ -7,6 +7,7 @@
#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/hrtimer_defs.h>
#include <linux/clocksource.h>
#include <vdso/datapage.h>
#include <vdso/helpers.h>
@ -64,10 +65,14 @@ static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
do {
seq = vdso_read_begin(vd);
if (IS_ENABLED(CONFIG_GENERIC_VDSO_CLOCK_MODE) &&
vd->clock_mode == VDSO_CLOCKMODE_NONE)
return -1;
cycles = __arch_get_hw_counter(vd->clock_mode);
ns = vdso_ts->nsec;
last = vd->cycle_last;
if (unlikely((s64)cycles < 0))
if (!IS_ENABLED(CONFIG_GENERIC_VDSO_CLOCK_MODE) &&
unlikely((s64)cycles < 0))
return -1;
ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
@ -132,10 +137,14 @@ static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
}
smp_rmb();
if (IS_ENABLED(CONFIG_GENERIC_VDSO_CLOCK_MODE) &&
vd->clock_mode == VDSO_CLOCKMODE_NONE)
return -1;
cycles = __arch_get_hw_counter(vd->clock_mode);
ns = vdso_ts->nsec;
last = vd->cycle_last;
if (unlikely((s64)cycles < 0))
if (!IS_ENABLED(CONFIG_GENERIC_VDSO_CLOCK_MODE) &&
unlikely((s64)cycles < 0))
return -1;
ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);