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authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
commit5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch)
treecc5c2d0a898769fd59549594fedb3ee6f84e59a0 /kernel/sched/clock.c
downloadlinux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz
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Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
Pull networking updates from Jakub Kicinski: "Core: - Add dedicated kmem_cache for typical/small skb->head, avoid having to access struct page at kfree time, and improve memory use. - Introduce sysctl to set default RPS configuration for new netdevs. - Define Netlink protocol specification format which can be used to describe messages used by each family and auto-generate parsers. Add tools for generating kernel data structures and uAPI headers. - Expose all net/core sysctls inside netns. - Remove 4s sleep in netpoll if carrier is instantly detected on boot. - Add configurable limit of MDB entries per port, and port-vlan. - Continue populating drop reasons throughout the stack. - Retire a handful of legacy Qdiscs and classifiers. Protocols: - Support IPv4 big TCP (TSO frames larger than 64kB). - Add IP_LOCAL_PORT_RANGE socket option, to control local port range on socket by socket basis. - Track and report in procfs number of MPTCP sockets used. - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path manager. - IPv6: don't check net.ipv6.route.max_size and rely on garbage collection to free memory (similarly to IPv4). - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986). - ICMP: add per-rate limit counters. - Add support for user scanning requests in ieee802154. - Remove static WEP support. - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate reporting. - WiFi 7 EHT channel puncturing support (client & AP). BPF: - Add a rbtree data structure following the "next-gen data structure" precedent set by recently added linked list, that is, by using kfunc + kptr instead of adding a new BPF map type. - Expose XDP hints via kfuncs with initial support for RX hash and timestamp metadata. - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to better support decap on GRE tunnel devices not operating in collect metadata. - Improve x86 JIT's codegen for PROBE_MEM runtime error checks. - Remove the need for trace_printk_lock for bpf_trace_printk and bpf_trace_vprintk helpers. - Extend libbpf's bpf_tracing.h support for tracing arguments of kprobes/uprobes and syscall as a special case. - Significantly reduce the search time for module symbols by livepatch and BPF. - Enable cpumasks to be used as kptrs, which is useful for tracing programs tracking which tasks end up running on which CPUs in different time intervals. - Add support for BPF trampoline on s390x and riscv64. - Add capability to export the XDP features supported by the NIC. - Add __bpf_kfunc tag for marking kernel functions as kfuncs. - Add cgroup.memory=nobpf kernel parameter option to disable BPF memory accounting for container environments. Netfilter: - Remove the CLUSTERIP target. It has been marked as obsolete for years, and we still have WARN splats wrt races of the out-of-band /proc interface installed by this target. - Add 'destroy' commands to nf_tables. They are identical to the existing 'delete' commands, but do not return an error if the referenced object (set, chain, rule...) did not exist. Driver API: - Improve cpumask_local_spread() locality to help NICs set the right IRQ affinity on AMD platforms. - Separate C22 and C45 MDIO bus transactions more clearly. - Introduce new DCB table to control DSCP rewrite on egress. - Support configuration of Physical Layer Collision Avoidance (PLCA) Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of shared medium Ethernet. - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing preemption of low priority frames by high priority frames. - Add support for controlling MACSec offload using netlink SET. - Rework devlink instance refcounts to allow registration and de-registration under the instance lock. Split the code into multiple files, drop some of the unnecessarily granular locks and factor out common parts of netlink operation handling. - Add TX frame aggregation parameters (for USB drivers). - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning messages with notifications for debug. - Allow offloading of UDP NEW connections via act_ct. - Add support for per action HW stats in TC. - Support hardware miss to TC action (continue processing in SW from a specific point in the action chain). - Warn if old Wireless Extension user space interface is used with modern cfg80211/mac80211 drivers. Do not support Wireless Extensions for Wi-Fi 7 devices at all. Everyone should switch to using nl80211 interface instead. - Improve the CAN bit timing configuration. Use extack to return error messages directly to user space, update the SJW handling, including the definition of a new default value that will benefit CAN-FD controllers, by increasing their oscillator tolerance. New hardware / drivers: - Ethernet: - nVidia BlueField-3 support (control traffic driver) - Ethernet support for imx93 SoCs - Motorcomm yt8531 gigabit Ethernet PHY - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA) - Microchip LAN8841 PHY (incl. cable diagnostics and PTP) - Amlogic gxl MDIO mux - WiFi: - RealTek RTL8188EU (rtl8xxxu) - Qualcomm Wi-Fi 7 devices (ath12k) - CAN: - Renesas R-Car V4H Drivers: - Bluetooth: - Set Per Platform Antenna Gain (PPAG) for Intel controllers. - Ethernet NICs: - Intel (1G, igc): - support TSN / Qbv / packet scheduling features of i226 model - Intel (100G, ice): - use GNSS subsystem instead of TTY - multi-buffer XDP support - extend support for GPIO pins to E823 devices - nVidia/Mellanox: - update the shared buffer configuration on PFC commands - implement PTP adjphase function for HW offset control - TC support for Geneve and GRE with VF tunnel offload - more efficient crypto key management method - multi-port eswitch support - Netronome/Corigine: - add DCB IEEE support - support IPsec offloading for NFP3800 - Freescale/NXP (enetc): - support XDP_REDIRECT for XDP non-linear buffers - improve reconfig, avoid link flap and waiting for idle - support MAC Merge layer - Other NICs: - sfc/ef100: add basic devlink support for ef100 - ionic: rx_push mode operation (writing descriptors via MMIO) - bnxt: use the auxiliary bus abstraction for RDMA - r8169: disable ASPM and reset bus in case of tx timeout - cpsw: support QSGMII mode for J721e CPSW9G - cpts: support pulse-per-second output - ngbe: add an mdio bus driver - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing - r8152: handle devices with FW with NCM support - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation - virtio-net: support multi buffer XDP - virtio/vsock: replace virtio_vsock_pkt with sk_buff - tsnep: XDP support - Ethernet high-speed switches: - nVidia/Mellanox (mlxsw): - add support for latency TLV (in FW control messages) - Microchip (sparx5): - separate explicit and implicit traffic forwarding rules, make the implicit rules always active - add support for egress DSCP rewrite - IS0 VCAP support (Ingress Classification) - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS etc.) - ES2 VCAP support (Egress Access Control) - support for Per-Stream Filtering and Policing (802.1Q, 8.6.5.1) - Ethernet embedded switches: - Marvell (mv88e6xxx): - add MAB (port auth) offload support - enable PTP receive for mv88e6390 - NXP (ocelot): - support MAC Merge layer - support for the the vsc7512 internal copper phys - Microchip: - lan9303: convert to PHYLINK - lan966x: support TC flower filter statistics - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x - lan937x: support Credit Based Shaper configuration - ksz9477: support Energy Efficient Ethernet - other: - qca8k: convert to regmap read/write API, use bulk operations - rswitch: Improve TX timestamp accuracy - Intel WiFi (iwlwifi): - EHT (Wi-Fi 7) rate reporting - STEP equalizer support: transfer some STEP (connection to radio on platforms with integrated wifi) related parameters from the BIOS to the firmware. - Qualcomm 802.11ax WiFi (ath11k): - IPQ5018 support - Fine Timing Measurement (FTM) responder role support - channel 177 support - MediaTek WiFi (mt76): - per-PHY LED support - mt7996: EHT (Wi-Fi 7) support - Wireless Ethernet Dispatch (WED) reset support - switch to using page pool allocator - RealTek WiFi (rtw89): - support new version of Bluetooth co-existance - Mobile: - rmnet: support TX aggregation" * tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits) page_pool: add a comment explaining the fragment counter usage net: ethtool: fix __ethtool_dev_mm_supported() implementation ethtool: pse-pd: Fix double word in comments xsk: add linux/vmalloc.h to xsk.c sefltests: netdevsim: wait for devlink instance after netns removal selftest: fib_tests: Always cleanup before exit net/mlx5e: Align IPsec ASO result memory to be as required by hardware net/mlx5e: TC, Set CT miss to the specific ct action instance net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG net/mlx5: Refactor tc miss handling to a single function net/mlx5: Kconfig: Make tc offload depend on tc skb extension net/sched: flower: Support hardware miss to tc action net/sched: flower: Move filter handle initialization earlier net/sched: cls_api: Support hardware miss to tc action net/sched: Rename user cookie and act cookie sfc: fix builds without CONFIG_RTC_LIB sfc: clean up some inconsistent indentings net/mlx4_en: Introduce flexible array to silence overflow warning net: lan966x: Fix possible deadlock inside PTP net/ulp: Remove redundant ->clone() test in inet_clone_ulp(). ...
Diffstat (limited to 'kernel/sched/clock.c')
-rw-r--r--kernel/sched/clock.c495
1 files changed, 495 insertions, 0 deletions
diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c
new file mode 100644
index 000000000..5732fa75e
--- /dev/null
+++ b/kernel/sched/clock.c
@@ -0,0 +1,495 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * sched_clock() for unstable CPU clocks
+ *
+ * Copyright (C) 2008 Red Hat, Inc., Peter Zijlstra
+ *
+ * Updates and enhancements:
+ * Copyright (C) 2008 Red Hat, Inc. Steven Rostedt <srostedt@redhat.com>
+ *
+ * Based on code by:
+ * Ingo Molnar <mingo@redhat.com>
+ * Guillaume Chazarain <guichaz@gmail.com>
+ *
+ *
+ * What this file implements:
+ *
+ * cpu_clock(i) provides a fast (execution time) high resolution
+ * clock with bounded drift between CPUs. The value of cpu_clock(i)
+ * is monotonic for constant i. The timestamp returned is in nanoseconds.
+ *
+ * ######################### BIG FAT WARNING ##########################
+ * # when comparing cpu_clock(i) to cpu_clock(j) for i != j, time can #
+ * # go backwards !! #
+ * ####################################################################
+ *
+ * There is no strict promise about the base, although it tends to start
+ * at 0 on boot (but people really shouldn't rely on that).
+ *
+ * cpu_clock(i) -- can be used from any context, including NMI.
+ * local_clock() -- is cpu_clock() on the current CPU.
+ *
+ * sched_clock_cpu(i)
+ *
+ * How it is implemented:
+ *
+ * The implementation either uses sched_clock() when
+ * !CONFIG_HAVE_UNSTABLE_SCHED_CLOCK, which means in that case the
+ * sched_clock() is assumed to provide these properties (mostly it means
+ * the architecture provides a globally synchronized highres time source).
+ *
+ * Otherwise it tries to create a semi stable clock from a mixture of other
+ * clocks, including:
+ *
+ * - GTOD (clock monotonic)
+ * - sched_clock()
+ * - explicit idle events
+ *
+ * We use GTOD as base and use sched_clock() deltas to improve resolution. The
+ * deltas are filtered to provide monotonicity and keeping it within an
+ * expected window.
+ *
+ * Furthermore, explicit sleep and wakeup hooks allow us to account for time
+ * that is otherwise invisible (TSC gets stopped).
+ *
+ */
+
+/*
+ * Scheduler clock - returns current time in nanosec units.
+ * This is default implementation.
+ * Architectures and sub-architectures can override this.
+ */
+notrace unsigned long long __weak sched_clock(void)
+{
+ return (unsigned long long)(jiffies - INITIAL_JIFFIES)
+ * (NSEC_PER_SEC / HZ);
+}
+EXPORT_SYMBOL_GPL(sched_clock);
+
+static DEFINE_STATIC_KEY_FALSE(sched_clock_running);
+
+#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
+/*
+ * We must start with !__sched_clock_stable because the unstable -> stable
+ * transition is accurate, while the stable -> unstable transition is not.
+ *
+ * Similarly we start with __sched_clock_stable_early, thereby assuming we
+ * will become stable, such that there's only a single 1 -> 0 transition.
+ */
+static DEFINE_STATIC_KEY_FALSE(__sched_clock_stable);
+static int __sched_clock_stable_early = 1;
+
+/*
+ * We want: ktime_get_ns() + __gtod_offset == sched_clock() + __sched_clock_offset
+ */
+__read_mostly u64 __sched_clock_offset;
+static __read_mostly u64 __gtod_offset;
+
+struct sched_clock_data {
+ u64 tick_raw;
+ u64 tick_gtod;
+ u64 clock;
+};
+
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct sched_clock_data, sched_clock_data);
+
+static __always_inline struct sched_clock_data *this_scd(void)
+{
+ return this_cpu_ptr(&sched_clock_data);
+}
+
+notrace static inline struct sched_clock_data *cpu_sdc(int cpu)
+{
+ return &per_cpu(sched_clock_data, cpu);
+}
+
+notrace int sched_clock_stable(void)
+{
+ return static_branch_likely(&__sched_clock_stable);
+}
+
+notrace static void __scd_stamp(struct sched_clock_data *scd)
+{
+ scd->tick_gtod = ktime_get_ns();
+ scd->tick_raw = sched_clock();
+}
+
+notrace static void __set_sched_clock_stable(void)
+{
+ struct sched_clock_data *scd;
+
+ /*
+ * Since we're still unstable and the tick is already running, we have
+ * to disable IRQs in order to get a consistent scd->tick* reading.
+ */
+ local_irq_disable();
+ scd = this_scd();
+ /*
+ * Attempt to make the (initial) unstable->stable transition continuous.
+ */
+ __sched_clock_offset = (scd->tick_gtod + __gtod_offset) - (scd->tick_raw);
+ local_irq_enable();
+
+ printk(KERN_INFO "sched_clock: Marking stable (%lld, %lld)->(%lld, %lld)\n",
+ scd->tick_gtod, __gtod_offset,
+ scd->tick_raw, __sched_clock_offset);
+
+ static_branch_enable(&__sched_clock_stable);
+ tick_dep_clear(TICK_DEP_BIT_CLOCK_UNSTABLE);
+}
+
+/*
+ * If we ever get here, we're screwed, because we found out -- typically after
+ * the fact -- that TSC wasn't good. This means all our clocksources (including
+ * ktime) could have reported wrong values.
+ *
+ * What we do here is an attempt to fix up and continue sort of where we left
+ * off in a coherent manner.
+ *
+ * The only way to fully avoid random clock jumps is to boot with:
+ * "tsc=unstable".
+ */
+notrace static void __sched_clock_work(struct work_struct *work)
+{
+ struct sched_clock_data *scd;
+ int cpu;
+
+ /* take a current timestamp and set 'now' */
+ preempt_disable();
+ scd = this_scd();
+ __scd_stamp(scd);
+ scd->clock = scd->tick_gtod + __gtod_offset;
+ preempt_enable();
+
+ /* clone to all CPUs */
+ for_each_possible_cpu(cpu)
+ per_cpu(sched_clock_data, cpu) = *scd;
+
+ printk(KERN_WARNING "TSC found unstable after boot, most likely due to broken BIOS. Use 'tsc=unstable'.\n");
+ printk(KERN_INFO "sched_clock: Marking unstable (%lld, %lld)<-(%lld, %lld)\n",
+ scd->tick_gtod, __gtod_offset,
+ scd->tick_raw, __sched_clock_offset);
+
+ static_branch_disable(&__sched_clock_stable);
+}
+
+static DECLARE_WORK(sched_clock_work, __sched_clock_work);
+
+notrace static void __clear_sched_clock_stable(void)
+{
+ if (!sched_clock_stable())
+ return;
+
+ tick_dep_set(TICK_DEP_BIT_CLOCK_UNSTABLE);
+ schedule_work(&sched_clock_work);
+}
+
+notrace void clear_sched_clock_stable(void)
+{
+ __sched_clock_stable_early = 0;
+
+ smp_mb(); /* matches sched_clock_init_late() */
+
+ if (static_key_count(&sched_clock_running.key) == 2)
+ __clear_sched_clock_stable();
+}
+
+notrace static void __sched_clock_gtod_offset(void)
+{
+ struct sched_clock_data *scd = this_scd();
+
+ __scd_stamp(scd);
+ __gtod_offset = (scd->tick_raw + __sched_clock_offset) - scd->tick_gtod;
+}
+
+void __init sched_clock_init(void)
+{
+ /*
+ * Set __gtod_offset such that once we mark sched_clock_running,
+ * sched_clock_tick() continues where sched_clock() left off.
+ *
+ * Even if TSC is buggered, we're still UP at this point so it
+ * can't really be out of sync.
+ */
+ local_irq_disable();
+ __sched_clock_gtod_offset();
+ local_irq_enable();
+
+ static_branch_inc(&sched_clock_running);
+}
+/*
+ * We run this as late_initcall() such that it runs after all built-in drivers,
+ * notably: acpi_processor and intel_idle, which can mark the TSC as unstable.
+ */
+static int __init sched_clock_init_late(void)
+{
+ static_branch_inc(&sched_clock_running);
+ /*
+ * Ensure that it is impossible to not do a static_key update.
+ *
+ * Either {set,clear}_sched_clock_stable() must see sched_clock_running
+ * and do the update, or we must see their __sched_clock_stable_early
+ * and do the update, or both.
+ */
+ smp_mb(); /* matches {set,clear}_sched_clock_stable() */
+
+ if (__sched_clock_stable_early)
+ __set_sched_clock_stable();
+
+ return 0;
+}
+late_initcall(sched_clock_init_late);
+
+/*
+ * min, max except they take wrapping into account
+ */
+
+static __always_inline u64 wrap_min(u64 x, u64 y)
+{
+ return (s64)(x - y) < 0 ? x : y;
+}
+
+static __always_inline u64 wrap_max(u64 x, u64 y)
+{
+ return (s64)(x - y) > 0 ? x : y;
+}
+
+/*
+ * update the percpu scd from the raw @now value
+ *
+ * - filter out backward motion
+ * - use the GTOD tick value to create a window to filter crazy TSC values
+ */
+static __always_inline u64 sched_clock_local(struct sched_clock_data *scd)
+{
+ u64 now, clock, old_clock, min_clock, max_clock, gtod;
+ s64 delta;
+
+again:
+ now = sched_clock();
+ delta = now - scd->tick_raw;
+ if (unlikely(delta < 0))
+ delta = 0;
+
+ old_clock = scd->clock;
+
+ /*
+ * scd->clock = clamp(scd->tick_gtod + delta,
+ * max(scd->tick_gtod, scd->clock),
+ * scd->tick_gtod + TICK_NSEC);
+ */
+
+ gtod = scd->tick_gtod + __gtod_offset;
+ clock = gtod + delta;
+ min_clock = wrap_max(gtod, old_clock);
+ max_clock = wrap_max(old_clock, gtod + TICK_NSEC);
+
+ clock = wrap_max(clock, min_clock);
+ clock = wrap_min(clock, max_clock);
+
+ if (!arch_try_cmpxchg64(&scd->clock, &old_clock, clock))
+ goto again;
+
+ return clock;
+}
+
+noinstr u64 local_clock(void)
+{
+ u64 clock;
+
+ if (static_branch_likely(&__sched_clock_stable))
+ return sched_clock() + __sched_clock_offset;
+
+ preempt_disable_notrace();
+ clock = sched_clock_local(this_scd());
+ preempt_enable_notrace();
+
+ return clock;
+}
+EXPORT_SYMBOL_GPL(local_clock);
+
+static notrace u64 sched_clock_remote(struct sched_clock_data *scd)
+{
+ struct sched_clock_data *my_scd = this_scd();
+ u64 this_clock, remote_clock;
+ u64 *ptr, old_val, val;
+
+#if BITS_PER_LONG != 64
+again:
+ /*
+ * Careful here: The local and the remote clock values need to
+ * be read out atomic as we need to compare the values and
+ * then update either the local or the remote side. So the
+ * cmpxchg64 below only protects one readout.
+ *
+ * We must reread via sched_clock_local() in the retry case on
+ * 32-bit kernels as an NMI could use sched_clock_local() via the
+ * tracer and hit between the readout of
+ * the low 32-bit and the high 32-bit portion.
+ */
+ this_clock = sched_clock_local(my_scd);
+ /*
+ * We must enforce atomic readout on 32-bit, otherwise the
+ * update on the remote CPU can hit inbetween the readout of
+ * the low 32-bit and the high 32-bit portion.
+ */
+ remote_clock = cmpxchg64(&scd->clock, 0, 0);
+#else
+ /*
+ * On 64-bit kernels the read of [my]scd->clock is atomic versus the
+ * update, so we can avoid the above 32-bit dance.
+ */
+ sched_clock_local(my_scd);
+again:
+ this_clock = my_scd->clock;
+ remote_clock = scd->clock;
+#endif
+
+ /*
+ * Use the opportunity that we have both locks
+ * taken to couple the two clocks: we take the
+ * larger time as the latest time for both
+ * runqueues. (this creates monotonic movement)
+ */
+ if (likely((s64)(remote_clock - this_clock) < 0)) {
+ ptr = &scd->clock;
+ old_val = remote_clock;
+ val = this_clock;
+ } else {
+ /*
+ * Should be rare, but possible:
+ */
+ ptr = &my_scd->clock;
+ old_val = this_clock;
+ val = remote_clock;
+ }
+
+ if (!try_cmpxchg64(ptr, &old_val, val))
+ goto again;
+
+ return val;
+}
+
+/*
+ * Similar to cpu_clock(), but requires local IRQs to be disabled.
+ *
+ * See cpu_clock().
+ */
+notrace u64 sched_clock_cpu(int cpu)
+{
+ struct sched_clock_data *scd;
+ u64 clock;
+
+ if (sched_clock_stable())
+ return sched_clock() + __sched_clock_offset;
+
+ if (!static_branch_likely(&sched_clock_running))
+ return sched_clock();
+
+ preempt_disable_notrace();
+ scd = cpu_sdc(cpu);
+
+ if (cpu != smp_processor_id())
+ clock = sched_clock_remote(scd);
+ else
+ clock = sched_clock_local(scd);
+ preempt_enable_notrace();
+
+ return clock;
+}
+EXPORT_SYMBOL_GPL(sched_clock_cpu);
+
+notrace void sched_clock_tick(void)
+{
+ struct sched_clock_data *scd;
+
+ if (sched_clock_stable())
+ return;
+
+ if (!static_branch_likely(&sched_clock_running))
+ return;
+
+ lockdep_assert_irqs_disabled();
+
+ scd = this_scd();
+ __scd_stamp(scd);
+ sched_clock_local(scd);
+}
+
+notrace void sched_clock_tick_stable(void)
+{
+ if (!sched_clock_stable())
+ return;
+
+ /*
+ * Called under watchdog_lock.
+ *
+ * The watchdog just found this TSC to (still) be stable, so now is a
+ * good moment to update our __gtod_offset. Because once we find the
+ * TSC to be unstable, any computation will be computing crap.
+ */
+ local_irq_disable();
+ __sched_clock_gtod_offset();
+ local_irq_enable();
+}
+
+/*
+ * We are going deep-idle (irqs are disabled):
+ */
+notrace void sched_clock_idle_sleep_event(void)
+{
+ sched_clock_cpu(smp_processor_id());
+}
+EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event);
+
+/*
+ * We just idled; resync with ktime.
+ */
+notrace void sched_clock_idle_wakeup_event(void)
+{
+ unsigned long flags;
+
+ if (sched_clock_stable())
+ return;
+
+ if (unlikely(timekeeping_suspended))
+ return;
+
+ local_irq_save(flags);
+ sched_clock_tick();
+ local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event);
+
+#else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */
+
+void __init sched_clock_init(void)
+{
+ static_branch_inc(&sched_clock_running);
+ local_irq_disable();
+ generic_sched_clock_init();
+ local_irq_enable();
+}
+
+notrace u64 sched_clock_cpu(int cpu)
+{
+ if (!static_branch_likely(&sched_clock_running))
+ return 0;
+
+ return sched_clock();
+}
+
+#endif /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */
+
+/*
+ * Running clock - returns the time that has elapsed while a guest has been
+ * running.
+ * On a guest this value should be local_clock minus the time the guest was
+ * suspended by the hypervisor (for any reason).
+ * On bare metal this function should return the same as local_clock.
+ * Architectures and sub-architectures can override this.
+ */
+notrace u64 __weak running_clock(void)
+{
+ return local_clock();
+}