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authorLinus Torvalds <torvalds@linux-foundation.org>2024-05-14 09:27:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2024-05-14 09:27:40 -0700
commit2d9db778ddca079228ef10e60bceea06b34b0eaa (patch)
tree141de3fcc8b32a0d495b36f461b5875681f5011e /rust
parent61deafa9ecf3f6d00c570774b0b38f439be543ac (diff)
parenta3825a7691585485e960cec04ce6667d176b7c67 (diff)
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 ...
Diffstat (limited to 'rust')
-rw-r--r--rust/kernel/time.rs63
1 files changed, 63 insertions, 0 deletions
diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs
index 25a896eed468..e3bb5e89f88d 100644
--- a/rust/kernel/time.rs
+++ b/rust/kernel/time.rs
@@ -4,6 +4,12 @@
//!
//! This module contains the kernel APIs related to time and timers that
//! have been ported or wrapped for usage by Rust code in the kernel.
+//!
+//! C header: [`include/linux/jiffies.h`](srctree/include/linux/jiffies.h).
+//! C header: [`include/linux/ktime.h`](srctree/include/linux/ktime.h).
+
+/// The number of nanoseconds per millisecond.
+pub const NSEC_PER_MSEC: i64 = bindings::NSEC_PER_MSEC as i64;
/// The time unit of Linux kernel. One jiffy equals (1/HZ) second.
pub type Jiffies = core::ffi::c_ulong;
@@ -18,3 +24,60 @@ pub fn msecs_to_jiffies(msecs: Msecs) -> Jiffies {
// matter what the argument is.
unsafe { bindings::__msecs_to_jiffies(msecs) }
}
+
+/// A Rust wrapper around a `ktime_t`.
+#[repr(transparent)]
+#[derive(Copy, Clone)]
+pub struct Ktime {
+ inner: bindings::ktime_t,
+}
+
+impl Ktime {
+ /// Create a `Ktime` from a raw `ktime_t`.
+ #[inline]
+ pub fn from_raw(inner: bindings::ktime_t) -> Self {
+ Self { inner }
+ }
+
+ /// Get the current time using `CLOCK_MONOTONIC`.
+ #[inline]
+ pub fn ktime_get() -> Self {
+ // SAFETY: It is always safe to call `ktime_get` outside of NMI context.
+ Self::from_raw(unsafe { bindings::ktime_get() })
+ }
+
+ /// Divide the number of nanoseconds by a compile-time constant.
+ #[inline]
+ fn divns_constant<const DIV: i64>(self) -> i64 {
+ self.to_ns() / DIV
+ }
+
+ /// Returns the number of nanoseconds.
+ #[inline]
+ pub fn to_ns(self) -> i64 {
+ self.inner
+ }
+
+ /// Returns the number of milliseconds.
+ #[inline]
+ pub fn to_ms(self) -> i64 {
+ self.divns_constant::<NSEC_PER_MSEC>()
+ }
+}
+
+/// Returns the number of milliseconds between two ktimes.
+#[inline]
+pub fn ktime_ms_delta(later: Ktime, earlier: Ktime) -> i64 {
+ (later - earlier).to_ms()
+}
+
+impl core::ops::Sub for Ktime {
+ type Output = Ktime;
+
+ #[inline]
+ fn sub(self, other: Ktime) -> Ktime {
+ Self {
+ inner: self.inner - other.inner,
+ }
+ }
+}