From: Thomas Gleixner tglx@linutronix.de
mainline inclusion from mainline-v5.13-rc1 commit b2c67cbe9f447312f5cdd7c6641b463f2349aec0 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8DWT1 CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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System time snapshots are not conveying information about the current clocksource which was used, but callers like the PTP KVM guest implementation have the requirement to evaluate the clocksource type to select the appropriate mechanism.
Introduce a clocksource id field in struct clocksource which is by default set to CSID_GENERIC (0). Clocksource implementations can set that field to a value which allows to identify the clocksource.
Store the clocksource id of the current clocksource in the system_time_snapshot so callers can evaluate which clocksource was used to take the snapshot and act accordingly.
Signed-off-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Jianyong Wu jianyong.wu@arm.com Signed-off-by: Marc Zyngier maz@kernel.org Link: https://lore.kernel.org/r/20201209060932.212364-5-jianyong.wu@arm.com Signed-off-by: Kunkun Jiang jiangkunkun@huawei.com Signed-off-by: Dongxu Sun sundongxu3@huawei.com --- include/linux/clocksource.h | 6 ++++++ include/linux/clocksource_ids.h | 11 +++++++++++ include/linux/timekeeping.h | 12 +++++++----- kernel/time/clocksource.c | 2 ++ kernel/time/timekeeping.c | 1 + 5 files changed, 27 insertions(+), 5 deletions(-) create mode 100644 include/linux/clocksource_ids.h
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index 4c3ecccc44ed..c68c28de91e4 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -17,6 +17,7 @@ #include <linux/timer.h> #include <linux/init.h> #include <linux/of.h> +#include <linux/clocksource_ids.h> #include <asm/div64.h> #include <asm/io.h>
@@ -62,6 +63,10 @@ struct module; * 400-499: Perfect * The ideal clocksource. A must-use where * available. + * @id: Defaults to CSID_GENERIC. The id value is captured + * in certain snapshot functions to allow callers to + * validate the clocksource from which the snapshot was + * taken. * @flags: Flags describing special properties * @enable: Optional function to enable the clocksource * @disable: Optional function to disable the clocksource @@ -100,6 +105,7 @@ struct clocksource { const char *name; struct list_head list; int rating; + enum clocksource_ids id; enum vdso_clock_mode vdso_clock_mode; u16 vdso_fix; u16 vdso_shift; diff --git a/include/linux/clocksource_ids.h b/include/linux/clocksource_ids.h new file mode 100644 index 000000000000..4d8e19e05328 --- /dev/null +++ b/include/linux/clocksource_ids.h @@ -0,0 +1,11 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_CLOCKSOURCE_IDS_H +#define _LINUX_CLOCKSOURCE_IDS_H + +/* Enum to give clocksources a unique identifier */ +enum clocksource_ids { + CSID_GENERIC = 0, + CSID_MAX, +}; + +#endif diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h index 7f7e4a3f4394..2ee05355333f 100644 --- a/include/linux/timekeeping.h +++ b/include/linux/timekeeping.h @@ -3,6 +3,7 @@ #define _LINUX_TIMEKEEPING_H
#include <linux/errno.h> +#include <linux/clocksource_ids.h>
/* Included from linux/ktime.h */
@@ -244,11 +245,12 @@ struct ktime_timestamps { * @cs_was_changed_seq: The sequence number of clocksource change events */ struct system_time_snapshot { - u64 cycles; - ktime_t real; - ktime_t raw; - unsigned int clock_was_set_seq; - u8 cs_was_changed_seq; + u64 cycles; + ktime_t real; + ktime_t raw; + enum clocksource_ids cs_id; + unsigned int clock_was_set_seq; + u8 cs_was_changed_seq; };
/** diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 74492f08660c..1657b5e74c64 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -1029,6 +1029,8 @@ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)
clocksource_arch_init(cs);
+ if (WARN_ON_ONCE((unsigned int)cs->id >= CSID_MAX)) + cs->id = CSID_GENERIC; 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", diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index c8d9b89a7571..85fb84e545fa 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1065,6 +1065,7 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot) do { seq = read_seqcount_begin(&tk_core.seq); now = tk_clock_read(&tk->tkr_mono); + systime_snapshot->cs_id = tk->tkr_mono.clock->id; systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq; systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq; base_real = ktime_add(tk->tkr_mono.base,