linux/Documentation
Linus Torvalds 2d9db778dd Timers and timekeeping updates:
- Core code:
 
    - Make timekeeping and VDSO time readouts resilent against math overflow:
 
      In guest context the kernel is prone to math overflow when the host
      defers the timer interrupt due to overload, malfunction or malice.
 
      This can be mitigated by checking the clocksource delta for the
      maximum deferrement which is readily available. If that value is
      exceeded then the code uses a slowpath function which can handle the
      multiplication overflow.
 
      This functionality is enabled unconditionally in the kernel, but made
      conditional in the VDSO code. The latter is conditional because it
      allows architectures to optimize the check so it is not causing
      performance regressions.
 
      On X86 this is achieved by reworking the existing check for negative
      TSC deltas as a negative delta obviously exceeds the maximum
      deferrement when it is evaluated as an unsigned value. That avoids two
      conditionals in the hotpath and allows to hide both the negative delta
      and the large delta handling in the same slow path.
 
    - Add an initial minimal ktime_t abstraction for Rust
 
    - The usual boring cleanups and enhancements
 
  - Drivers:
 
    - Boring updates to device trees and trivial enhancements in various
      drivers.
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Merge tag 'timers-core-2024-05-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timers and timekeeping updates from Thomas Gleixner:
 "Core code:

   - Make timekeeping and VDSO time readouts resilent against math
     overflow:

     In guest context the kernel is prone to math overflow when the host
     defers the timer interrupt due to overload, malfunction or malice.

     This can be mitigated by checking the clocksource delta for the
     maximum deferrement which is readily available. If that value is
     exceeded then the code uses a slowpath function which can handle
     the multiplication overflow.

     This functionality is enabled unconditionally in the kernel, but
     made conditional in the VDSO code. The latter is conditional
     because it allows architectures to optimize the check so it is not
     causing performance regressions.

     On X86 this is achieved by reworking the existing check for
     negative TSC deltas as a negative delta obviously exceeds the
     maximum deferrement when it is evaluated as an unsigned value. That
     avoids two conditionals in the hotpath and allows to hide both the
     negative delta and the large delta handling in the same slow path.

   - Add an initial minimal ktime_t abstraction for Rust

   - The usual boring cleanups and enhancements

  Drivers:

   - Boring updates to device trees and trivial enhancements in various
     drivers"

* tag 'timers-core-2024-05-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits)
  clocksource/drivers/arm_arch_timer: Mark hisi_161010101_oem_info const
  clocksource/drivers/timer-ti-dm: Remove an unused field in struct dmtimer
  clocksource/drivers/renesas-ostm: Avoid reprobe after successful early probe
  clocksource/drivers/renesas-ostm: Allow OSTM driver to reprobe for RZ/V2H(P) SoC
  dt-bindings: timer: renesas: ostm: Document Renesas RZ/V2H(P) SoC
  rust: time: doc: Add missing C header links
  clocksource: Make the int help prompt unit readable in ncurses
  hrtimer: Rename __hrtimer_hres_active() to hrtimer_hres_active()
  timerqueue: Remove never used function timerqueue_node_expires()
  rust: time: Add Ktime
  vdso: Fix powerpc build U64_MAX undeclared error
  clockevents: Convert s[n]printf() to sysfs_emit()
  clocksource: Convert s[n]printf() to sysfs_emit()
  clocksource: Make watchdog and suspend-timing multiplication overflow safe
  timekeeping: Let timekeeping_cycles_to_ns() handle both under and overflow
  timekeeping: Make delta calculation overflow safe
  timekeeping: Prepare timekeeping_cycles_to_ns() for overflow safety
  timekeeping: Fold in timekeeping_delta_to_ns()
  timekeeping: Consolidate timekeeping helpers
  timekeeping: Refactor timekeeping helpers
  ...
2024-05-14 09:27:40 -07:00
..
ABI blk-throttle: remove CONFIG_BLK_DEV_THROTTLING_LOW 2024-05-09 09:44:55 -06:00
accel
accounting
admin-guide Scheduler changes for v6.10: 2024-05-13 17:18:51 -07:00
arch - Add a tracepoint to read out LLC occupancy of resource monitor IDs with the 2024-05-14 09:04:37 -07:00
block
bpf bpf, docs: Rename legacy conformance group to packet 2024-03-04 14:31:06 +01:00
cdrom
core-api Another not-too-busy cycle for documentation, including: 2024-05-13 10:51:53 -07:00
cpu-freq
crypto
dev-tools kcsan: Introduce __data_racy type qualifier 2024-05-13 10:13:39 -07:00
devicetree Timers and timekeeping updates: 2024-05-14 09:27:40 -07:00
doc-guide doc: fix spelling about ReStructured Text 2024-04-02 10:07:51 -06:00
driver-api This update includes the following changes: 2024-05-13 14:53:05 -07:00
fault-injection
fb
features
filesystems Another not-too-busy cycle for documentation, including: 2024-05-13 10:51:53 -07:00
firmware-guide More ACPI updates for 6.9-rc1 2024-03-19 11:15:14 -07:00
firmware_class
fpga
gpu
hid
hwmon hwmon: (aspeed-g6-pwm-tacho): Support for ASPEED g6 PWM/Fan tach 2024-03-07 10:50:16 -08:00
i2c Documentation: i2c: Document that client auto-detection is a legacy mechanism 2024-03-07 09:42:09 +01:00
iio docs: iio: add documentation for adis16475 driver 2024-02-28 19:26:36 +00:00
images
infiniband
input
isdn
kbuild Documentation/llvm: Note s390 LLVM=1 support with LLVM 18.1.0 and newer 2024-03-31 21:09:50 +09:00
kernel-hacking
leds
litmus-tests Documentation/litmus-tests: Make cmpxchg() tests safe for klitmus 2024-05-06 14:29:21 -07:00
livepatch
locking
maintainer
mhi
misc-devices
mm Another not-too-busy cycle for documentation, including: 2024-05-13 10:51:53 -07:00
netlabel
netlink netlink: specs: Add missing bridge linkinfo attrs 2024-05-06 19:06:07 -07:00
networking Documentation: Add documentation for eswitch attribute 2024-03-28 18:20:08 -07:00
nvdimm
nvme
PCI
pcmcia
peci
power Documentation: power: Fix typo in suspend and interrupts doc 2024-03-13 20:51:11 +01:00
process Update the -tip maintainers merge policy document wrt. merge window timing. 2024-05-13 17:33:48 -07:00
RCU doc: Remove references to arrayRCU.rst 2024-04-09 15:13:05 +02:00
rust Rust changes for v6.10 2024-05-13 15:13:54 -07:00
scheduler Linux 6.9-rc1 2024-03-25 11:32:29 +01:00
scsi
security Another not-too-busy cycle for documentation, including: 2024-05-13 10:51:53 -07:00
sound
sphinx docs: kernel_include.py: Cope with docutils 0.21 2024-05-02 09:50:59 -06:00
sphinx-static
spi spi: docs: spidev: fix echo command format 2024-03-19 18:37:55 +00:00
staging
target
tee Documentation: tee: Add TS-TEE driver 2024-04-03 14:03:09 +02:00
timers sched/isolation: Prevent boot crash when the boot CPU is nohz_full 2024-04-28 10:07:12 +02:00
tools tools/rtla: Add -U/--user-load option to timerlat 2024-03-20 05:39:06 +01:00
trace Documentation: tracing: Fix spelling mistakes 2024-05-07 08:00:25 -06:00
translations Scheduler changes for v6.10: 2024-05-13 17:18:51 -07:00
usb
userspace-api media updates for v6.9-rc1 2024-03-15 11:36:54 -07:00
virt Documentation: kvm/sev: clarify usage of KVM_MEMORY_ENCRYPT_OP 2024-03-18 19:03:53 -04:00
w1
watchdog
wmi platform/x86: wmi: Update documentation regarding _WED 2024-02-27 14:44:31 +02:00
.gitignore
atomic_bitops.txt
atomic_t.txt Documentation/atomic_t: Emphasize that failed atomic operations give no ordering 2024-05-06 14:29:04 -07:00
Changes
CodingStyle
conf.py docs: Restore "smart quotes" for quotes 2024-02-28 15:48:18 -07:00
docutils.conf
dontdiff
index.rst doc: fix spelling about ReStructured Text 2024-04-02 10:07:51 -06:00
Kconfig
Makefile docs: Detect variable fonts and suggest denylisting them 2024-04-10 14:10:13 -06:00
memory-barriers.txt
SubmittingPatches
subsystem-apis.rst