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x86/vdso: Move VDSO clocksource state tracking to callback

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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.

X86 abuses the function which retrieves the architecture specific clock
mode storage to mark the clocksource as used in the VDSO. That's silly
because this is invoked on every tick when the VDSO data is updated.

Move this functionality to the clocksource::enable() callback so it gets
invoked once when the clocksource is installed. This allows to make the
clock mode storage generic.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>  (Hyper-V parts)
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> (VDSO parts)
Acked-by: Juergen Gross <jgross@suse.com> (Xen parts)
Link: https://lkml.kernel.org/r/20200207124402.934519777@linutronix.de
This commit is contained in:
Thomas Gleixner 2020-02-07 13:38:54 +01:00
parent 3bd142a46b
commit eec399dd86
9 changed files with 65 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/x86/entry/vdso/vma.c
View File

@ -38,6 +38,8 @@ struct vdso_data *arch_get_vdso_data(void *vvar_page)
}
#undef EMIT_VVAR
unsigned int vclocks_used __read_mostly;
#if defined(CONFIG_X86_64)
unsigned int __read_mostly vdso64_enabled = 1;
#endif
@ -445,6 +447,8 @@ __setup("vdso=", vdso_setup);
static int __init init_vdso(void)
{
BUILD_BUG_ON(VCLOCK_MAX >= 32);
init_vdso_image(&vdso_image_64);
#ifdef CONFIG_X86_X32_ABI

12
arch/x86/include/asm/clocksource.h
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@ -14,4 +14,16 @@ struct arch_clocksource_data {
int vclock_mode;
};
extern unsigned int vclocks_used;
static inline bool vclock_was_used(int vclock)
{
return READ_ONCE(vclocks_used) & (1U << vclock);
}
static inline void vclocks_set_used(unsigned int which)
{
WRITE_ONCE(vclocks_used, READ_ONCE(vclocks_used) | (1 << which));
}
#endif /* _ASM_X86_CLOCKSOURCE_H */

2
arch/x86/include/asm/mshyperv.h
View File

@ -47,6 +47,8 @@ typedef int (*hyperv_fill_flush_list_func)(
wrmsrl(HV_X64_MSR_REFERENCE_TSC, val)
#define hv_set_clocksource_vdso(val) \
((val).archdata.vclock_mode = VCLOCK_HVCLOCK)
#define hv_enable_vdso_clocksource() \
vclocks_set_used(VCLOCK_HVCLOCK);
#define hv_get_raw_timer() rdtsc_ordered()
void hyperv_callback_vector(void);

10
arch/x86/include/asm/vdso/vsyscall.h
View File

@ -10,8 +10,6 @@
#include <asm/vgtod.h>
#include <asm/vvar.h>
int vclocks_used __read_mostly;
DEFINE_VVAR(struct vdso_data, _vdso_data);
/*
* Update the vDSO data page to keep in sync with kernel timekeeping.
@ -26,13 +24,7 @@ struct vdso_data *__x86_get_k_vdso_data(void)
static __always_inline
int __x86_get_clock_mode(struct timekeeper *tk)
{
int vclock_mode = tk->tkr_mono.clock->archdata.vclock_mode;
/* Mark the new vclock used. */
BUILD_BUG_ON(VCLOCK_MAX >= 32);
WRITE_ONCE(vclocks_used, READ_ONCE(vclocks_used) | (1 << vclock_mode));
return vclock_mode;
return tk->tkr_mono.clock->archdata.vclock_mode;
}
#define __arch_get_clock_mode __x86_get_clock_mode

6
arch/x86/include/asm/vgtod.h
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@ -15,10 +15,4 @@ typedef u64 gtod_long_t;
typedef unsigned long gtod_long_t;
#endif
extern int vclocks_used;
static inline bool vclock_was_used(int vclock)
{
return READ_ONCE(vclocks_used) & (1 << vclock);
}
#endif /* _ASM_X86_VGTOD_H */

7
arch/x86/kernel/kvmclock.c
View File

@ -159,12 +159,19 @@ bool kvm_check_and_clear_guest_paused(void)
return ret;
}
static int kvm_cs_enable(struct clocksource *cs)
{
vclocks_set_used(VCLOCK_PVCLOCK);
return 0;
}
struct clocksource kvm_clock = {
.name = "kvm-clock",
.read = kvm_clock_get_cycles,
.rating = 400,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.enable = kvm_cs_enable,
};
EXPORT_SYMBOL_GPL(kvm_clock);

32
arch/x86/kernel/tsc.c
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@ -1108,17 +1108,24 @@ static void tsc_cs_tick_stable(struct clocksource *cs)
sched_clock_tick_stable();
}
static int tsc_cs_enable(struct clocksource *cs)
{
vclocks_set_used(VCLOCK_TSC);
return 0;
}
/*
* .mask MUST be CLOCKSOURCE_MASK(64). See comment above read_tsc()
*/
static struct clocksource clocksource_tsc_early = {
.name = "tsc-early",
.rating = 299,
.read = read_tsc,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS |
.name = "tsc-early",
.rating = 299,
.read = read_tsc,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS |
CLOCK_SOURCE_MUST_VERIFY,
.archdata = { .vclock_mode = VCLOCK_TSC },
.archdata = { .vclock_mode = VCLOCK_TSC },
.enable = tsc_cs_enable,
.resume = tsc_resume,
.mark_unstable = tsc_cs_mark_unstable,
.tick_stable = tsc_cs_tick_stable,
@ -1131,14 +1138,15 @@ static struct clocksource clocksource_tsc_early = {
* been found good.
*/
static struct clocksource clocksource_tsc = {
.name = "tsc",
.rating = 300,
.read = read_tsc,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS |
.name = "tsc",
.rating = 300,
.read = read_tsc,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS |
CLOCK_SOURCE_VALID_FOR_HRES |
CLOCK_SOURCE_MUST_VERIFY,
.archdata = { .vclock_mode = VCLOCK_TSC },
.archdata = { .vclock_mode = VCLOCK_TSC },
.enable = tsc_cs_enable,
.resume = tsc_resume,
.mark_unstable = tsc_cs_mark_unstable,
.tick_stable = tsc_cs_tick_stable,

17
arch/x86/xen/time.c
View File

@ -145,12 +145,19 @@ static struct notifier_block xen_pvclock_gtod_notifier = {
.notifier_call = xen_pvclock_gtod_notify,
};
static int xen_cs_enable(struct clocksource *cs)
{
vclocks_set_used(VCLOCK_PVCLOCK);
return 0;
}
static struct clocksource xen_clocksource __read_mostly = {
.name = "xen",
.rating = 400,
.read = xen_clocksource_get_cycles,
.mask = ~0,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.name = "xen",
.rating = 400,
.read = xen_clocksource_get_cycles,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.enable = xen_cs_enable,
};
/*

7
drivers/clocksource/hyperv_timer.c
View File

@ -369,6 +369,12 @@ static void resume_hv_clock_tsc(struct clocksource *arg)
hv_set_reference_tsc(tsc_msr);
}
static int hv_cs_enable(struct clocksource *cs)
{
hv_enable_vdso_clocksource();
return 0;
}
static struct clocksource hyperv_cs_tsc = {
.name = "hyperv_clocksource_tsc_page",
.rating = 250,
@ -377,6 +383,7 @@ static struct clocksource hyperv_cs_tsc = {
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.suspend= suspend_hv_clock_tsc,
.resume = resume_hv_clock_tsc,
.enable = hv_cs_enable,
};
static u64 notrace read_hv_clock_msr(void)