[PATCH 2/2] rust: cpumask: Add getters for globally defined cpumasks

Mitchell Levy
2025-11-05T23:16:28Z

Add getters for the global cpumasks documented in
`include/linux/cpumask.h`, specifically:
- cpu_possible_mask
- cpu_online_mask
- cpu_enabled_mask
- cpu_present_mask
- cpu_active_mask

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Suggested-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Mitchell Levy <levymitchell0@gmail.com>
---
rust/kernel/cpumask.rs | 46 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)

diff --git a/rust/kernel/cpumask.rs b/rust/kernel/cpumask.rs
index b7401848f59e..a6a130092fcb 100644
--- a/rust/kernel/cpumask.rs
+++ b/rust/kernel/cpumask.rs
@@ -77,6 +77,52 @@ pub unsafe fn as_ref<'a>(ptr: *const bindings::cpumask) -> &'a Self {
unsafe { &*ptr.cast() }
}

+ /// Get a CPU mask representing possible CPUs; has bit `cpu` set iff cpu is populatable
+ #[inline]
+ pub fn possible_cpus() -> &'static Self {
+ // SAFETY: `__cpu_possible_mask` is a valid global provided by the kernel that lives
+ // forever.
+ unsafe { Cpumask::as_ref(&raw const bindings::__cpu_possible_mask) }
+ }
+
+ /// Get a CPU mask representing online CPUs; has bit `cpu` set iff cpu available to the
+ /// scheduler
+ #[inline]
+ pub fn online_cpus() -> &'static Self {
+ // SAFETY: `__cpu_online_mask` is a valid global provided by the kernel that lives forever.
+ // Since we wrap the returned pointer in an `Opaque`, it's ok that `__cpu_online_mask`
+ // may change its value.
+ unsafe { Cpumask::as_ref(&raw const bindings::__cpu_online_mask) }
+ }
+
+ /// Get a CPU mask representing enabled CPUs; has bit `cpu` set iff cpu can be brought online
+ #[inline]
+ pub fn enabled_cpus() -> &'static Self {
+ // SAFETY: `__cpu_enabled_mask` is a valid global provided by the kernel that lives forever.
+ // Since we wrap the returned pointer in an `Opaque`, it's ok that `__cpu_enabled_mask`
+ // may change its value.
+ unsafe { Cpumask::as_ref(&raw const bindings::__cpu_enabled_mask) }
+ }
+
+ /// Get a CPU mask representing present CPUs; has bit `cpu` set iff cpu is populated
+ #[inline]
+ pub fn present_cpus() -> &'static Self {
+ // SAFETY: `__cpu_present_mask` is a valid global provided by the kernel that lives
+ // forever. Since we wrap the returned pointer in an `Opaque`, it's ok that
+ // `__cpu_present_mask` may change its value.
+ unsafe { Cpumask::as_ref(&raw const bindings::__cpu_present_mask) }
+ }
+
+ /// Get a CPU mask representing active CPUs; has bit `cpu` set iff cpu is available to
+ /// migration.
+ #[inline]
+ pub fn active_cpus() -> &'static Self {
+ // SAFETY: `__cpu_active_mask` is a valid global provided by the kernel that lives forever.
+ // Since we wrap the returned pointer in an `Opaque`, it's ok that `__cpu_active_mask`
+ // may change its value.
+ unsafe { Cpumask::as_ref(&raw const bindings::__cpu_active_mask) }
+ }
+
/// Obtain the raw `struct cpumask` pointer.
pub fn as_raw(&self) -> *mut bindings::cpumask {
let this: *const Self = self;

--
2.34.1