diff options
Diffstat (limited to 'rust/kernel')
| -rw-r--r-- | rust/kernel/cpu.rs | 125 | ||||
| -rw-r--r-- | rust/kernel/cpufreq.rs | 173 | ||||
| -rw-r--r-- | rust/kernel/cpumask.rs | 51 |
3 files changed, 287 insertions, 62 deletions
diff --git a/rust/kernel/cpu.rs b/rust/kernel/cpu.rs index 10c5c3b25873..b75403b0eb56 100644 --- a/rust/kernel/cpu.rs +++ b/rust/kernel/cpu.rs @@ -6,6 +6,127 @@ use crate::{bindings, device::Device, error::Result, prelude::ENODEV}; +/// Returns the maximum number of possible CPUs in the current system configuration. +#[inline] +pub fn nr_cpu_ids() -> u32 { + #[cfg(any(NR_CPUS_1, CONFIG_FORCE_NR_CPUS))] + { + bindings::NR_CPUS + } + + #[cfg(not(any(NR_CPUS_1, CONFIG_FORCE_NR_CPUS)))] + // SAFETY: `nr_cpu_ids` is a valid global provided by the kernel. + unsafe { + bindings::nr_cpu_ids + } +} + +/// The CPU ID. +/// +/// Represents a CPU identifier as a wrapper around an [`u32`]. +/// +/// # Invariants +/// +/// The CPU ID lies within the range `[0, nr_cpu_ids())`. +/// +/// # Examples +/// +/// ``` +/// use kernel::cpu::CpuId; +/// +/// let cpu = 0; +/// +/// // SAFETY: 0 is always a valid CPU number. +/// let id = unsafe { CpuId::from_u32_unchecked(cpu) }; +/// +/// assert_eq!(id.as_u32(), cpu); +/// assert!(CpuId::from_i32(0).is_some()); +/// assert!(CpuId::from_i32(-1).is_none()); +/// ``` +#[derive(Copy, Clone, PartialEq, Eq, Debug)] +pub struct CpuId(u32); + +impl CpuId { + /// Creates a new [`CpuId`] from the given `id` without checking bounds. + /// + /// # Safety + /// + /// The caller must ensure that `id` is a valid CPU ID (i.e., `0 <= id < nr_cpu_ids()`). + #[inline] + pub unsafe fn from_i32_unchecked(id: i32) -> Self { + debug_assert!(id >= 0); + debug_assert!((id as u32) < nr_cpu_ids()); + + // INVARIANT: The function safety guarantees `id` is a valid CPU id. + Self(id as u32) + } + + /// Creates a new [`CpuId`] from the given `id`, checking that it is valid. + pub fn from_i32(id: i32) -> Option<Self> { + if id < 0 || id as u32 >= nr_cpu_ids() { + None + } else { + // INVARIANT: `id` has just been checked as a valid CPU ID. + Some(Self(id as u32)) + } + } + + /// Creates a new [`CpuId`] from the given `id` without checking bounds. + /// + /// # Safety + /// + /// The caller must ensure that `id` is a valid CPU ID (i.e., `0 <= id < nr_cpu_ids()`). + #[inline] + pub unsafe fn from_u32_unchecked(id: u32) -> Self { + debug_assert!(id < nr_cpu_ids()); + + // Ensure the `id` fits in an [`i32`] as it's also representable that way. + debug_assert!(id <= i32::MAX as u32); + + // INVARIANT: The function safety guarantees `id` is a valid CPU id. + Self(id) + } + + /// Creates a new [`CpuId`] from the given `id`, checking that it is valid. + pub fn from_u32(id: u32) -> Option<Self> { + if id >= nr_cpu_ids() { + None + } else { + // INVARIANT: `id` has just been checked as a valid CPU ID. + Some(Self(id)) + } + } + + /// Returns CPU number. + #[inline] + pub fn as_u32(&self) -> u32 { + self.0 + } + + /// Returns the ID of the CPU the code is currently running on. + /// + /// The returned value is considered unstable because it may change + /// unexpectedly due to preemption or CPU migration. It should only be + /// used when the context ensures that the task remains on the same CPU + /// or the users could use a stale (yet valid) CPU ID. + pub fn current() -> Self { + // SAFETY: raw_smp_processor_id() always returns a valid CPU ID. + unsafe { Self::from_u32_unchecked(bindings::raw_smp_processor_id()) } + } +} + +impl From<CpuId> for u32 { + fn from(id: CpuId) -> Self { + id.as_u32() + } +} + +impl From<CpuId> for i32 { + fn from(id: CpuId) -> Self { + id.as_u32() as i32 + } +} + /// Creates a new instance of CPU's device. /// /// # Safety @@ -17,9 +138,9 @@ use crate::{bindings, device::Device, error::Result, prelude::ENODEV}; /// Callers must ensure that the CPU device is not used after it has been unregistered. /// This can be achieved, for example, by registering a CPU hotplug notifier and removing /// any references to the CPU device within the notifier's callback. -pub unsafe fn from_cpu(cpu: u32) -> Result<&'static Device> { +pub unsafe fn from_cpu(cpu: CpuId) -> Result<&'static Device> { // SAFETY: It is safe to call `get_cpu_device()` for any CPU. - let ptr = unsafe { bindings::get_cpu_device(cpu) }; + let ptr = unsafe { bindings::get_cpu_device(u32::from(cpu)) }; if ptr.is_null() { return Err(ENODEV); } diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs index b0a9c6182aec..11b03e9d7e89 100644 --- a/rust/kernel/cpufreq.rs +++ b/rust/kernel/cpufreq.rs @@ -10,6 +10,7 @@ use crate::{ clk::Hertz, + cpu::CpuId, cpumask, device::{Bound, Device}, devres::Devres, @@ -465,8 +466,9 @@ impl Policy { /// Returns the primary CPU for the [`Policy`]. #[inline] - pub fn cpu(&self) -> u32 { - self.as_ref().cpu + pub fn cpu(&self) -> CpuId { + // SAFETY: The C API guarantees that `cpu` refers to a valid CPU number. + unsafe { CpuId::from_u32_unchecked(self.as_ref().cpu) } } /// Returns the minimum frequency for the [`Policy`]. @@ -525,7 +527,7 @@ impl Policy { #[inline] pub fn generic_get(&self) -> Result<u32> { // SAFETY: By the type invariant, the pointer stored in `self` is valid. - Ok(unsafe { bindings::cpufreq_generic_get(self.cpu()) }) + Ok(unsafe { bindings::cpufreq_generic_get(u32::from(self.cpu())) }) } /// Provides a wrapper to the register with energy model using the OPP core. @@ -678,9 +680,9 @@ impl Policy { struct PolicyCpu<'a>(&'a mut Policy); impl<'a> PolicyCpu<'a> { - fn from_cpu(cpu: u32) -> Result<Self> { + fn from_cpu(cpu: CpuId) -> Result<Self> { // SAFETY: It is safe to call `cpufreq_cpu_get` for any valid CPU. - let ptr = from_err_ptr(unsafe { bindings::cpufreq_cpu_get(cpu) })?; + let ptr = from_err_ptr(unsafe { bindings::cpufreq_cpu_get(u32::from(cpu)) })?; Ok(Self( // SAFETY: The `ptr` is guaranteed to be valid and remains valid for the lifetime of @@ -1055,8 +1057,11 @@ impl<T: Driver> Registration<T> { impl<T: Driver> Registration<T> { /// Driver's `init` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn init_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int { + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn init_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int { from_result(|| { // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the // lifetime of `policy`. @@ -1070,8 +1075,11 @@ impl<T: Driver> Registration<T> { /// Driver's `exit` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn exit_callback(ptr: *mut bindings::cpufreq_policy) { + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn exit_callback(ptr: *mut bindings::cpufreq_policy) { // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the // lifetime of `policy`. let policy = unsafe { Policy::from_raw_mut(ptr) }; @@ -1082,8 +1090,11 @@ impl<T: Driver> Registration<T> { /// Driver's `online` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn online_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int { + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn online_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int { from_result(|| { // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the // lifetime of `policy`. @@ -1094,8 +1105,13 @@ impl<T: Driver> Registration<T> { /// Driver's `offline` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn offline_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int { + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn offline_callback( + ptr: *mut bindings::cpufreq_policy, + ) -> kernel::ffi::c_int { from_result(|| { // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the // lifetime of `policy`. @@ -1106,8 +1122,13 @@ impl<T: Driver> Registration<T> { /// Driver's `suspend` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn suspend_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int { + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn suspend_callback( + ptr: *mut bindings::cpufreq_policy, + ) -> kernel::ffi::c_int { from_result(|| { // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the // lifetime of `policy`. @@ -1118,8 +1139,11 @@ impl<T: Driver> Registration<T> { /// Driver's `resume` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn resume_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int { + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn resume_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int { from_result(|| { // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the // lifetime of `policy`. @@ -1130,8 +1154,11 @@ impl<T: Driver> Registration<T> { /// Driver's `ready` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn ready_callback(ptr: *mut bindings::cpufreq_policy) { + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn ready_callback(ptr: *mut bindings::cpufreq_policy) { // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the // lifetime of `policy`. let policy = unsafe { Policy::from_raw_mut(ptr) }; @@ -1140,8 +1167,13 @@ impl<T: Driver> Registration<T> { /// Driver's `verify` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn verify_callback(ptr: *mut bindings::cpufreq_policy_data) -> kernel::ffi::c_int { + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn verify_callback( + ptr: *mut bindings::cpufreq_policy_data, + ) -> kernel::ffi::c_int { from_result(|| { // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the // lifetime of `policy`. @@ -1152,8 +1184,13 @@ impl<T: Driver> Registration<T> { /// Driver's `setpolicy` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn setpolicy_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int { + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn setpolicy_callback( + ptr: *mut bindings::cpufreq_policy, + ) -> kernel::ffi::c_int { from_result(|| { // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the // lifetime of `policy`. @@ -1164,8 +1201,11 @@ impl<T: Driver> Registration<T> { /// Driver's `target` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn target_callback( + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn target_callback( ptr: *mut bindings::cpufreq_policy, target_freq: u32, relation: u32, @@ -1180,8 +1220,11 @@ impl<T: Driver> Registration<T> { /// Driver's `target_index` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn target_index_callback( + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn target_index_callback( ptr: *mut bindings::cpufreq_policy, index: u32, ) -> kernel::ffi::c_int { @@ -1200,8 +1243,11 @@ impl<T: Driver> Registration<T> { /// Driver's `fast_switch` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn fast_switch_callback( + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn fast_switch_callback( ptr: *mut bindings::cpufreq_policy, target_freq: u32, ) -> kernel::ffi::c_uint { @@ -1212,21 +1258,31 @@ impl<T: Driver> Registration<T> { } /// Driver's `adjust_perf` callback. - extern "C" fn adjust_perf_callback( + /// + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + unsafe extern "C" fn adjust_perf_callback( cpu: u32, min_perf: usize, target_perf: usize, capacity: usize, ) { - if let Ok(mut policy) = PolicyCpu::from_cpu(cpu) { + // SAFETY: The C API guarantees that `cpu` refers to a valid CPU number. + let cpu_id = unsafe { CpuId::from_u32_unchecked(cpu) }; + + if let Ok(mut policy) = PolicyCpu::from_cpu(cpu_id) { T::adjust_perf(&mut policy, min_perf, target_perf, capacity); } } /// Driver's `get_intermediate` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn get_intermediate_callback( + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn get_intermediate_callback( ptr: *mut bindings::cpufreq_policy, index: u32, ) -> kernel::ffi::c_uint { @@ -1243,8 +1299,11 @@ impl<T: Driver> Registration<T> { /// Driver's `target_intermediate` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn target_intermediate_callback( + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn target_intermediate_callback( ptr: *mut bindings::cpufreq_policy, index: u32, ) -> kernel::ffi::c_int { @@ -1262,12 +1321,24 @@ impl<T: Driver> Registration<T> { } /// Driver's `get` callback. - extern "C" fn get_callback(cpu: u32) -> kernel::ffi::c_uint { - PolicyCpu::from_cpu(cpu).map_or(0, |mut policy| T::get(&mut policy).map_or(0, |f| f)) + /// + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + unsafe extern "C" fn get_callback(cpu: u32) -> kernel::ffi::c_uint { + // SAFETY: The C API guarantees that `cpu` refers to a valid CPU number. + let cpu_id = unsafe { CpuId::from_u32_unchecked(cpu) }; + + PolicyCpu::from_cpu(cpu_id).map_or(0, |mut policy| T::get(&mut policy).map_or(0, |f| f)) } /// Driver's `update_limit` callback. - extern "C" fn update_limits_callback(ptr: *mut bindings::cpufreq_policy) { + /// + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn update_limits_callback(ptr: *mut bindings::cpufreq_policy) { // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the // lifetime of `policy`. let policy = unsafe { Policy::from_raw_mut(ptr) }; @@ -1276,10 +1347,16 @@ impl<T: Driver> Registration<T> { /// Driver's `bios_limit` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn bios_limit_callback(cpu: i32, limit: *mut u32) -> kernel::ffi::c_int { + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn bios_limit_callback(cpu: i32, limit: *mut u32) -> kernel::ffi::c_int { + // SAFETY: The C API guarantees that `cpu` refers to a valid CPU number. + let cpu_id = unsafe { CpuId::from_i32_unchecked(cpu) }; + from_result(|| { - let mut policy = PolicyCpu::from_cpu(cpu as u32)?; + let mut policy = PolicyCpu::from_cpu(cpu_id)?; // SAFETY: `limit` is guaranteed by the C code to be valid. T::bios_limit(&mut policy, &mut (unsafe { *limit })).map(|()| 0) @@ -1288,8 +1365,11 @@ impl<T: Driver> Registration<T> { /// Driver's `set_boost` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn set_boost_callback( + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn set_boost_callback( ptr: *mut bindings::cpufreq_policy, state: i32, ) -> kernel::ffi::c_int { @@ -1303,8 +1383,11 @@ impl<T: Driver> Registration<T> { /// Driver's `register_em` callback. /// - /// SAFETY: Called from C. Inputs must be valid pointers. - extern "C" fn register_em_callback(ptr: *mut bindings::cpufreq_policy) { + /// # Safety + /// + /// - This function may only be called from the cpufreq C infrastructure. + /// - The pointer arguments must be valid pointers. + unsafe extern "C" fn register_em_callback(ptr: *mut bindings::cpufreq_policy) { // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the // lifetime of `policy`. let policy = unsafe { Policy::from_raw_mut(ptr) }; diff --git a/rust/kernel/cpumask.rs b/rust/kernel/cpumask.rs index c90bfac9346a..19c607709b5f 100644 --- a/rust/kernel/cpumask.rs +++ b/rust/kernel/cpumask.rs @@ -6,6 +6,7 @@ use crate::{ alloc::{AllocError, Flags}, + cpu::CpuId, prelude::*, types::Opaque, }; @@ -35,9 +36,10 @@ use core::ops::{Deref, DerefMut}; /// /// ``` /// use kernel::bindings; +/// use kernel::cpu::CpuId; /// use kernel::cpumask::Cpumask; /// -/// fn set_clear_cpu(ptr: *mut bindings::cpumask, set_cpu: u32, clear_cpu: i32) { +/// fn set_clear_cpu(ptr: *mut bindings::cpumask, set_cpu: CpuId, clear_cpu: CpuId) { /// // SAFETY: The `ptr` is valid for writing and remains valid for the lifetime of the /// // returned reference. /// let mask = unsafe { Cpumask::as_mut_ref(ptr) }; @@ -90,9 +92,9 @@ impl Cpumask { /// This mismatches kernel naming convention and corresponds to the C /// function `__cpumask_set_cpu()`. #[inline] - pub fn set(&mut self, cpu: u32) { + pub fn set(&mut self, cpu: CpuId) { // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `__cpumask_set_cpu`. - unsafe { bindings::__cpumask_set_cpu(cpu, self.as_raw()) }; + unsafe { bindings::__cpumask_set_cpu(u32::from(cpu), self.as_raw()) }; } /// Clear `cpu` in the cpumask. @@ -101,19 +103,19 @@ impl Cpumask { /// This mismatches kernel naming convention and corresponds to the C /// function `__cpumask_clear_cpu()`. #[inline] - pub fn clear(&mut self, cpu: i32) { + pub fn clear(&mut self, cpu: CpuId) { // SAFETY: By the type invariant, `self.as_raw` is a valid argument to // `__cpumask_clear_cpu`. - unsafe { bindings::__cpumask_clear_cpu(cpu, self.as_raw()) }; + unsafe { bindings::__cpumask_clear_cpu(i32::from(cpu), self.as_raw()) }; } /// Test `cpu` in the cpumask. /// /// Equivalent to the kernel's `cpumask_test_cpu` API. #[inline] - pub fn test(&self, cpu: i32) -> bool { + pub fn test(&self, cpu: CpuId) -> bool { // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_test_cpu`. - unsafe { bindings::cpumask_test_cpu(cpu, self.as_raw()) } + unsafe { bindings::cpumask_test_cpu(i32::from(cpu), self.as_raw()) } } /// Set all CPUs in the cpumask. @@ -178,21 +180,40 @@ impl Cpumask { /// The following example demonstrates how to create and update a [`CpumaskVar`]. /// /// ``` +/// use kernel::cpu::CpuId; /// use kernel::cpumask::CpumaskVar; /// /// let mut mask = CpumaskVar::new_zero(GFP_KERNEL).unwrap(); /// /// assert!(mask.empty()); -/// mask.set(2); -/// assert!(mask.test(2)); -/// mask.set(3); -/// assert!(mask.test(3)); -/// assert_eq!(mask.weight(), 2); +/// let mut count = 0; +/// +/// let cpu2 = CpuId::from_u32(2); +/// if let Some(cpu) = cpu2 { +/// mask.set(cpu); +/// assert!(mask.test(cpu)); +/// count += 1; +/// } +/// +/// let cpu3 = CpuId::from_u32(3); +/// if let Some(cpu) = cpu3 { +/// mask.set(cpu); +/// assert!(mask.test(cpu)); +/// count += 1; +/// } +/// +/// assert_eq!(mask.weight(), count); /// /// let mask2 = CpumaskVar::try_clone(&mask).unwrap(); -/// assert!(mask2.test(2)); -/// assert!(mask2.test(3)); -/// assert_eq!(mask2.weight(), 2); +/// +/// if let Some(cpu) = cpu2 { +/// assert!(mask2.test(cpu)); +/// } +/// +/// if let Some(cpu) = cpu3 { +/// assert!(mask2.test(cpu)); +/// } +/// assert_eq!(mask2.weight(), count); /// ``` pub struct CpumaskVar { #[cfg(CONFIG_CPUMASK_OFFSTACK)] |