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//! The RTOS kernel #[cfg(feature = "priority_boost")] use core::sync::atomic::{AtomicBool, Ordering}; use core::{fmt, marker::PhantomData, mem::forget, num::NonZeroUsize, ops::Range}; use crate::{ time::{Duration, Time}, utils::{binary_heap::VecLike, BinUInteger, Init}, }; #[macro_use] pub mod cfg; mod error; mod event_group; mod hunk; mod interrupt; mod mutex; mod semaphore; mod startup; mod state; mod task; mod timeout; mod timer; mod utils; mod wait; pub use self::{ error::*, event_group::*, hunk::*, interrupt::*, mutex::*, semaphore::*, startup::*, task::*, timeout::*, timer::*, wait::*, }; /// Numeric value used to identify various kinds of kernel objects. pub type Id = NonZeroUsize; /// Provides access to the global API functions exposed by the kernel. /// /// This trait is automatically implemented on "system" types that have /// sufficient trait `impl`s to instantiate the kernel. #[doc(include = "./common.md")] pub trait Kernel: Port + KernelCfg2 + Sized + 'static { type DebugPrinter: fmt::Debug + Send + Sync; /// Get an object that implements [`Debug`](fmt::Debug) for dumping the /// current kernel state. /// /// Note that printing this object might consume a large amount of stack /// space. fn debug() -> Self::DebugPrinter; /// Activate [CPU Lock]. /// /// Returns [`BadContext`] if CPU Lock is already active. /// /// [CPU Lock]: crate#system-states /// [`BadContext`]: CpuLockError::BadContext fn acquire_cpu_lock() -> Result<(), CpuLockError>; /// Deactivate [CPU Lock]. /// /// Returns [`BadContext`] if CPU Lock is already inactive. /// /// [CPU Lock]: crate#system-states /// [`BadContext`]: CpuLockError::BadContext /// /// # Safety /// /// CPU Lock is useful for creating a critical section. By making this /// method `unsafe`, safe code is prevented from interfering with a critical /// section. /// /// Deactivating CPU Lock in a boot context is disallowed. unsafe fn release_cpu_lock() -> Result<(), CpuLockError>; /// Return a flag indicating whether CPU Lock is currently active. fn has_cpu_lock() -> bool; /// Activate [Priority Boost]. /// /// Returns [`BadContext`] if Priority Boost is already active, the /// calling context is not a task context, or CPU Lock is active. /// /// [Priority Boost]: crate#system-states /// [`BadContext`]: CpuLockError::BadContext #[cfg(feature = "priority_boost")] #[doc(cfg(feature = "priority_boost"))] fn boost_priority() -> Result<(), BoostPriorityError>; /// Deactivate [Priority Boost]. /// /// Returns [`BadContext`] if Priority Boost is already inactive, the /// calling context is not a task context, or CPU Lock is active. /// /// [Priority Boost]: crate#system-states /// [`BadContext`]: CpuLockError::BadContext /// /// # Safety /// /// Priority Boost is useful for creating a critical section. By making this /// method `unsafe`, safe code is prevented from interfering with a critical /// section. unsafe fn unboost_priority() -> Result<(), BoostPriorityError>; /// Return a flag indicating whether [Priority Boost] is currently active. /// /// [Priority Boost]: crate#system-states fn is_priority_boost_active() -> bool; /// Get the current [system time]. /// /// [system time]: crate#kernel-timing /// /// This method will return [`TimeError::BadContext`] when called in a /// non-task context. /// /// <div class="admonition-follows"></div> /// /// > **Rationale:** This restriction originates from μITRON4.0. It's /// > actually unnecessary in the current implementation, but allows /// > headroom for potential changes in the implementation. #[cfg(feature = "system_time")] #[doc(cfg(feature = "system_time"))] fn time() -> Result<Time, TimeError>; /// Set the current [system time]. /// /// This method *does not change* the relative arrival times of outstanding /// timed events nor the relative time of the frontier (a concept used in /// the definition of [`adjust_time`]). /// /// [system time]: crate#kernel-timing /// [`adjust_time`]: Self::adjust_time /// /// This method will return [`TimeError::BadContext`] when called in a /// non-task context. /// /// <div class="admonition-follows"></div> /// /// > **Rationale:** This restriction originates from μITRON4.0. It's /// > actually unnecessary in the current implementation, but allows /// > headroom for potential changes in the implementation. fn set_time(time: Time) -> Result<(), TimeError>; #[cfg_attr(doc, svgbobdoc::transform)] /// Move the current [system time] forward or backward by the specified /// amount. /// /// This method *changes* the relative arrival times of outstanding /// timed events. /// /// The kernel uses a limited number of bits to represent the arrival times /// of outstanding timed events. This means that there's some upper bound /// on how far the system time can be moved away without breaking internal /// invariants. This method ensures this bound is not violated by the /// methods described below. This method will return `BadObjectState` if /// this check fails. /// /// **Moving Forward (`delta > 0`):** If there are no outstanding time /// events, adjustment in this direction is unbounded. Otherwise, let /// `t` be the relative arrival time (in relation to the current time) of /// the earliest outstanding time event. /// If `t - delta < -`[`TIME_USER_HEADROOM`] (i.e., if the adjustment would /// make the event overdue by more than `TIME_USER_HEADROOM`), the check /// will fail. /// /// The events made overdue by the call will be processed when the port /// timer driver announces a new tick. It's unspecified whether this happens /// before or after the call returns. /// /// **Moving Backward (`delta < 0`):** First, we introduce the concept of /// **a frontier**. The frontier represents the point of time at which the /// system time advanced the most. Usually, the frontier is identical to /// the current system time because the system time keeps moving forward /// (a). However, adjusting the system time to past makes them temporarily /// separate from each other (b). In this case, the frontier stays in place /// until the system time eventually catches up with the frontier and they /// start moving together again (c). /// /// <center> /// ```svgbob /// system time /// ----*------------------------ /// ^ frontier /// /// (b) /// /// --------*-------------------- /// system time ^ /// ----------*------------ ------------*---------------- /// ^ frontier ^ /// -----------------*----------- /// (a) ^ /// ----------------------*------ /// ^ /// (c) /// ``` /// </center> /// /// Let `frontier` be the current relative time of the frontier (in relation /// to the current time). If `frontier - delta > `[`TIME_USER_HEADROOM`] /// (i.e., if the adjustment would move the frontier too far away), the /// check will fail. /// /// [system time]: crate#kernel-timing /// /// <div class="admonition-follows"></div> /// /// > **Observation:** Even under ideal circumstances, all timed events are /// > bound to be overdue by a very small extent because of various factors /// > such as an intrinsic interrupt latency, insufficient timer resolution, /// > and uses of CPU Lock. This means the minimum value of `t` in the above /// > explanation is not `0` but a somewhat smaller value. The consequence /// > is that `delta` can never reliably be `>= TIME_USER_HEADROOM`. /// /// <div class="admonition-follows"></div> /// /// > **Relation to Other Specifications:** `adj_tim` from /// > [the TOPPERS 3rd generation kernels] /// /// [the TOPPERS 3rd generation kernels]: https://www.toppers.jp/index.html /// /// <div class="admonition-follows"></div> /// /// > **Rationale:** When moving the system time forward, capping by a /// > frontier instead of an actual latest arrival time has advantages over /// > other schemes that involve tracking the latest arrival time: /// > /// > - Linear-scanning all outstanding timed events to find the latest /// > arrival time would take a linear time. /// > /// > - Using a double-ended data structure for an event queue, such as a /// > balanced search tree and double heaps, would increase the runtime /// > cost of maintaining the structure. /// > /// > Also, the gap between the current time and the frontier is completely /// > in control of the code that calls `adjust_time`, making the behavior /// > more predictable. fn adjust_time(delta: Duration) -> Result<(), AdjustTimeError>; // TODO: get time resolution? /// Terminate the current task, putting it into the Dormant state. /// /// The kernel (to be precise, the port) makes an implicit call to this /// function when a task entry point function returns. /// /// # Safety /// /// On a successful call, this function destroys the current task's stack /// without running any destructors on stack-allocated objects and renders /// all references pointing to such objects invalid. The caller is /// responsible for taking this possibility into account and ensuring this /// doesn't lead to an undefined behavior. /// unsafe fn exit_task() -> Result<!, ExitTaskError>; /// Put the current task into the Waiting state until the task's token is /// made available by [`Task::unpark`]. The token is initially absent when /// the task is activated. /// /// The token will be consumed when this method returns successfully. /// /// This system service may block. Therefore, calling this method is not /// allowed in [a non-waitable context] and will return `Err(BadContext)`. /// /// [a non-waitable context]: crate#contexts fn park() -> Result<(), ParkError>; /// [`park`](Self::park) with timeout. /// /// This system service may block. Therefore, calling this method is not /// allowed in [a non-waitable context] and will return `Err(BadContext)`. /// /// [a non-waitable context]: crate#contexts fn park_timeout(timeout: Duration) -> Result<(), ParkTimeoutError>; /// Block the current task for the specified duration. fn sleep(duration: Duration) -> Result<(), SleepError>; } impl<T: Port + KernelCfg2 + 'static> Kernel for T { #[inline] fn acquire_cpu_lock() -> Result<(), CpuLockError> { // Safety: `try_enter_cpu_lock` is only meant to be called by // the kernel if unsafe { Self::try_enter_cpu_lock() } { Ok(()) } else { Err(CpuLockError::BadContext) } } #[inline] unsafe fn release_cpu_lock() -> Result<(), CpuLockError> { if !Self::is_cpu_lock_active() { Err(CpuLockError::BadContext) } else { // Safety: CPU Lock active unsafe { Self::leave_cpu_lock() }; Ok(()) } } #[inline] fn has_cpu_lock() -> bool { Self::is_cpu_lock_active() } #[cfg_attr(not(feature = "inline_syscall"), inline(never))] #[cfg(feature = "priority_boost")] fn boost_priority() -> Result<(), BoostPriorityError> { state::boost_priority::<Self>() } #[cfg_attr(not(feature = "inline_syscall"), inline(never))] unsafe fn unboost_priority() -> Result<(), BoostPriorityError> { state::unboost_priority::<Self>() } #[inline] #[cfg(feature = "priority_boost")] fn is_priority_boost_active() -> bool { Self::state().priority_boost.load(Ordering::Relaxed) } #[inline] #[cfg(not(feature = "priority_boost"))] fn is_priority_boost_active() -> bool { false } #[cfg_attr(not(feature = "inline_syscall"), inline(never))] #[cfg(feature = "system_time")] fn time() -> Result<Time, TimeError> { timeout::system_time::<Self>() } #[cfg_attr(not(feature = "inline_syscall"), inline(never))] fn set_time(time: Time) -> Result<(), TimeError> { timeout::set_system_time::<Self>(time) } #[cfg_attr(not(feature = "inline_syscall"), inline(never))] fn adjust_time(delta: Duration) -> Result<(), AdjustTimeError> { timeout::adjust_system_and_event_time::<Self>(delta) } #[cfg_attr(not(feature = "inline_syscall"), inline(never))] unsafe fn exit_task() -> Result<!, ExitTaskError> { // Safety: Just forwarding the function call unsafe { exit_current_task::<Self>() } } #[cfg_attr(not(feature = "inline_syscall"), inline(never))] fn park() -> Result<(), ParkError> { task::park_current_task::<Self>() } #[cfg_attr(not(feature = "inline_syscall"), inline(never))] fn park_timeout(timeout: Duration) -> Result<(), ParkTimeoutError> { task::park_current_task_timeout::<Self>(timeout) } #[cfg_attr(not(feature = "inline_syscall"), inline(never))] fn sleep(timeout: Duration) -> Result<(), SleepError> { task::put_current_task_on_sleep_timeout::<Self>(timeout) } type DebugPrinter = KernelDebugPrinter<Self>; /// Get an object that implements [`Debug`](fmt::Debug) for dumping the /// current kernel state. /// /// Note that printing this object might consume a large amount of stack /// space. #[inline] fn debug() -> Self::DebugPrinter { KernelDebugPrinter(PhantomData) } } /// The object returned by [`Kernel::debug`]. Implements [`fmt::Debug`]. /// /// **This type is exempt from the API stability guarantee.** pub struct KernelDebugPrinter<T>(PhantomData<T>); impl<T: Kernel> fmt::Debug for KernelDebugPrinter<T> { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { struct PoolPrinter<'a, T>(&'a [T]); impl<T: fmt::Debug> fmt::Debug for PoolPrinter<'_, T> { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { // dictionary-style printing with key = object ID, value = object f.debug_map().entries(self.0.iter().enumerate()).finish() } } f.debug_struct("Kernel") .field("state", T::state()) .field("task_cb_pool", &PoolPrinter(T::task_cb_pool())) .field( "event_group_cb_pool", &PoolPrinter(T::event_group_cb_pool()), ) .field("mutex_cb_pool", &PoolPrinter(T::mutex_cb_pool())) .field("semaphore_cb_pool", &PoolPrinter(T::semaphore_cb_pool())) .field("timer_cb_pool", &PoolPrinter(T::timer_cb_pool())) .finish() } } /// Associates "system" types with kernel-private data. Use [`build!`] to /// implement. /// /// Customizable things needed by both of `Port` and `KernelCfg2` should live /// here because `Port` cannot refer to an associated item defined by /// `KernelCfg2`. /// /// # Safety /// /// This is only intended to be implemented by `build!`. pub unsafe trait KernelCfg1: Sized + Send + Sync + 'static { /// The number of task priority levels. const NUM_TASK_PRIORITY_LEVELS: usize; /// Unsigned integer type capable of representing the range /// `0..NUM_TASK_PRIORITY_LEVELS`. type TaskPriority: BinUInteger; /// Task ready queue type. #[doc(hidden)] type TaskReadyQueue: readyqueue::Queue<Self>; // FIXME: This is a work-around for trait methods being uncallable in `const fn` // <https://github.com/rust-lang/rfcs/pull/2632> // <https://github.com/rust-lang/const-eval/pull/8> /// All possible values of `TaskPriority`. /// /// `TASK_PRIORITY_LEVELS[i]` is equivalent to /// `TaskPriority::try_from(i).unwrap()` except that the latter doesn't work /// in `const fn`. const TASK_PRIORITY_LEVELS: &'static [Self::TaskPriority]; } /// Implemented by a port. This trait contains items related to low-level /// operations for controlling CPU states and context switching. /// /// # Safety /// /// Implementing a port is inherently unsafe because it's responsible for /// initializing the execution environment and providing a dispatcher /// implementation. /// /// These methods are only meant to be called by the kernel. #[doc(include = "./common.md")] #[allow(clippy::missing_safety_doc)] pub unsafe trait PortThreading: KernelCfg1 { type PortTaskState: Send + Sync + Init + fmt::Debug + 'static; /// The initial value of [`TaskCb::port_task_state`] for all tasks. #[allow(clippy::declare_interior_mutable_const)] // it's intentional const PORT_TASK_STATE_INIT: Self::PortTaskState; /// The default stack size for tasks. const STACK_DEFAULT_SIZE: usize = 1024; /// The alignment requirement for task stack regions. /// /// Both ends of stack regions are aligned by `STACK_ALIGN`. It's /// automatically enforced by the kernel configurator for automatically /// allocated stack regions (this applies to tasks created without /// [`stack_hunk`]). The kernel configurator does not check the alignemnt /// for manually-allocated stack regions. /// /// [`stack_hunk`]: crate::kernel::cfg::CfgTaskBuilder::stack_hunk /// [`StackHunk`]: crate::kernel::StackHunk const STACK_ALIGN: usize = core::mem::size_of::<usize>(); /// Transfer the control to the dispatcher, discarding the current /// (startup) context. [`State::running_task`] is `None` at this point. /// The dispatcher should call [`PortToKernel::choose_running_task`] to find /// the next task to run and transfer the control to that task. /// /// Precondition: CPU Lock active, a boot context unsafe fn dispatch_first_task() -> !; /// Yield the processor. /// /// In a task context, this method immediately transfers the control to /// a dispatcher. The dispatcher should call /// [`PortToKernel::choose_running_task`] to find the next task to run and /// transfer the control to that task. /// /// In an interrupt context, the effect of this method will be deferred /// until the processor completes the execution of all active interrupt /// handler threads. /// /// Precondition: CPU Lock inactive /// /// <div class="admonition-follows"></div> /// /// > **Port Implementation Note:** One way to handle the interrupt context /// > case is to set a flag variable and check it in the epilogue of a /// > first-level interrupt handler. Another way is to raise a low-priority /// > interrupt (such as PendSV in Arm-M) and implement dispatching in the /// > handler. unsafe fn yield_cpu(); /// Destroy the state of the previously running task (`task`, which has /// already been removed from [`State::running_task`]) and proceed to /// the dispatcher. /// /// Precondition: CPU Lock active unsafe fn exit_and_dispatch(task: &'static task::TaskCb<Self>) -> !; /// Disable all kernel-managed interrupts (this state is called *CPU Lock*). /// /// Precondition: CPU Lock inactive unsafe fn enter_cpu_lock(); /// Re-enable kernel-managed interrupts previously disabled by /// `enter_cpu_lock`, thus deactivating the CPU Lock state. /// /// Precondition: CPU Lock active unsafe fn leave_cpu_lock(); /// Activate CPU Lock. Return `true` iff CPU Lock was inactive before the /// call. unsafe fn try_enter_cpu_lock() -> bool { if Self::is_cpu_lock_active() { false } else { // Safety: CPU Lock inactive unsafe { Self::enter_cpu_lock() }; true } } /// Prepare the task for activation. More specifically, set the current /// program counter to [`TaskAttr::entry_point`] and the current stack /// pointer to either end of [`TaskAttr::stack`], ensuring the task will /// start execution from `entry_point` next time the task receives the /// control. /// /// Do not call this for a running task. Calling this for a dormant task is /// always safe. For tasks in other states, whether this method is safe is /// dependent on how the programming language the task code is written in /// is implemented. In particular, this is unsafe for Rust task code because /// it might violate the requirement of [`Pin`] if there's a `Pin` pointing /// to something on the task's stack. /// /// [`Pin`]: core::pin::Pin /// /// Precondition: CPU Lock active unsafe fn initialize_task_state(task: &'static task::TaskCb<Self>); /// Return a flag indicating whether a CPU Lock state is active. fn is_cpu_lock_active() -> bool; /// Return a flag indicating whether the current context is /// [an task context]. /// /// [an task context]: crate#contexts fn is_task_context() -> bool; } /// Implemented by a port. This trait contains items related to controlling /// interrupt lines. /// /// # Safety /// /// Implementing a port is inherently unsafe because it's responsible for /// initializing the execution environment and providing a dispatcher /// implementation. /// /// These methods are only meant to be called by the kernel. #[doc(include = "./common.md")] #[allow(clippy::missing_safety_doc)] pub unsafe trait PortInterrupts: KernelCfg1 { /// The range of interrupt priority values considered [managed]. /// /// Defaults to `0..0` (empty) when unspecified. /// /// [managed]: crate#interrupt-handling-framework #[allow(clippy::reversed_empty_ranges)] // on purpose const MANAGED_INTERRUPT_PRIORITY_RANGE: Range<InterruptPriority> = 0..0; /// The list of interrupt lines which are considered [managed]. /// /// Defaults to `&[]` (empty) when unspecified. /// /// This is useful when the driver employs a fixed priority scheme and /// doesn't support changing interrupt line priorities. /// /// [managed]: crate#interrupt-handling-framework const MANAGED_INTERRUPT_LINES: &'static [InterruptNum] = &[]; /// Set the priority of the specified interrupt line. /// /// Precondition: CPU Lock active. Task context or boot phase. unsafe fn set_interrupt_line_priority( _line: InterruptNum, _priority: InterruptPriority, ) -> Result<(), SetInterruptLinePriorityError> { Err(SetInterruptLinePriorityError::NotSupported) } /// Enable the specified interrupt line. unsafe fn enable_interrupt_line(_line: InterruptNum) -> Result<(), EnableInterruptLineError> { Err(EnableInterruptLineError::NotSupported) } /// Disable the specified interrupt line. unsafe fn disable_interrupt_line(_line: InterruptNum) -> Result<(), EnableInterruptLineError> { Err(EnableInterruptLineError::NotSupported) } /// Set the pending flag of the specified interrupt line. unsafe fn pend_interrupt_line(_line: InterruptNum) -> Result<(), PendInterruptLineError> { Err(PendInterruptLineError::NotSupported) } /// Clear the pending flag of the specified interrupt line. unsafe fn clear_interrupt_line(_line: InterruptNum) -> Result<(), ClearInterruptLineError> { Err(ClearInterruptLineError::NotSupported) } /// Read the pending flag of the specified interrupt line. unsafe fn is_interrupt_line_pending( _line: InterruptNum, ) -> Result<bool, QueryInterruptLineError> { Err(QueryInterruptLineError::NotSupported) } } /// Implemented by a port. This trait contains items related to controlling /// a system timer. /// /// # Safety /// /// These methods are only meant to be called by the kernel. #[doc(include = "./common.md")] #[allow(clippy::missing_safety_doc)] pub trait PortTimer { /// The maximum value that [`tick_count`] can return. Must be greater /// than zero. /// /// [`tick_count`]: Self::tick_count const MAX_TICK_COUNT: UTicks; /// The maximum value that can be passed to [`pend_tick_after`]. Must be /// greater than zero. /// /// This value should be somewhat smaller than `MAX_TICK_COUNT`. The /// difference determines the kernel's resilience against overdue /// timer interrupts. /// /// This is ignored and can take any value if `pend_tick_after` is /// implemented as no-op. /// /// [`pend_tick_after`]: Self::pend_tick_after const MAX_TIMEOUT: UTicks; /// Read the current tick count (timer value). /// /// This value steadily increases over time. When it goes past /// `MAX_TICK_COUNT`, it “wraps around” to `0`. /// /// The returned value must be in range `0..=`[`MAX_TICK_COUNT`]. /// /// Precondition: CPU Lock active /// /// [`MAX_TICK_COUNT`]: Self::MAX_TICK_COUNT unsafe fn tick_count() -> UTicks; /// Indicate that `tick_count_delta` ticks may elapse before the kernel /// should receive a call to [`PortToKernel::timer_tick`]. /// /// “`tick_count_delta` ticks” include the current (ongoing) tick. For /// example, `tick_count_delta == 1` means `timer_tick` should be /// preferably called right after the next tick boundary. /// /// The driver might track time in a coarser granularity than microseconds. /// In this case, the driver should wait until the earliest moment when /// `tick_count() >= current_tick_count + tick_count_delta` (where /// `current_tick_count` is the current value of `tick_count()`; not taking /// the wrap-around behavior into account) is fulfilled and call /// `timer_tick`. /// /// It's legal to ignore the calls to this method entirely and call /// `timer_tick` at a steady rate, resulting in something similar to a /// “tickful” kernel. The default implementation does nothing assuming that /// the port driver is implemented in this way. /// /// `tick_count_delta` must be in range `1..=`[`MAX_TIMEOUT`]. /// /// Precondition: CPU Lock active /// /// [`MAX_TIMEOUT`]: Self::MAX_TIMEOUT unsafe fn pend_tick_after(tick_count_delta: UTicks) { let _ = tick_count_delta; } /// Pend a call to [`PortToKernel::timer_tick`] as soon as possible. /// /// The default implementation calls `pend_tick_after(1)`. /// /// Precondition: CPU Lock active unsafe fn pend_tick() { unsafe { Self::pend_tick_after(1) }; } } /// Unsigned integer type representing a tick count used by /// [a port timer driver]. The period of each tick is fixed at one microsecond. /// /// [a port timer driver]: PortTimer pub type UTicks = u32; /// Represents a particular group of traits that a port should implement. pub trait Port: PortThreading + PortInterrupts + PortTimer {} impl<T: PortThreading + PortInterrupts + PortTimer> Port for T {} /// Methods intended to be called by a port. /// /// # Safety /// /// These are only meant to be called by the port. #[allow(clippy::missing_safety_doc)] pub trait PortToKernel { /// Initialize runtime structures. /// /// Should be called for exactly once by the port before calling into any /// user (application) or kernel code. /// /// Precondition: CPU Lock active, Preboot phase // TODO: Explain phases unsafe fn boot() -> !; /// Determine the next task to run and store it in [`State::running_task_ptr`]. /// /// Precondition: CPU Lock active / Postcondition: CPU Lock active unsafe fn choose_running_task(); /// Called by [a port timer driver] to “announce” new ticks. /// /// This method can be called anytime, but the driver is expected to attempt /// to ensure the calls occur near tick boundaries. For an optimal /// operation, the driver should implement [`pend_tick_after`] and handle /// the calls made by the kernel to figure out the optimal moment to call /// `timer_tick`. /// /// This method will call `pend_tick` or `pend_tick_after`. /// /// [a port timer driver]: PortTimer /// [`pend_tick_after`]: PortTimer::pend_tick_after /// /// Precondition: CPU Lock inactive, an interrupt context unsafe fn timer_tick(); } impl<System: Kernel> PortToKernel for System { unsafe fn boot() -> ! { let mut lock = unsafe { utils::assume_cpu_lock::<Self>() }; // Initialize all tasks for cb in Self::task_cb_pool() { task::init_task(lock.borrow_mut(), cb); } // Initialize the timekeeping system System::state().timeout.init(lock.borrow_mut()); for cb in Self::timer_cb_pool() { timer::init_timer(lock.borrow_mut(), cb); } // Initialize all interrupt lines // Safety: The contents of `INTERRUPT_ATTR` has been generated and // verified by `panic_if_unmanaged_safety_is_violated` for *unsafe // safety*. Thus the use of unmanaged priority values has been already // authorized. unsafe { System::INTERRUPT_ATTR.init(lock.borrow_mut()); } // Call startup hooks for hook in Self::STARTUP_HOOKS { // Safety: This is the intended place to call startup hooks. unsafe { (hook.start)(hook.param) }; } forget(lock); // Safety: CPU Lock is active, Startup phase unsafe { Self::dispatch_first_task(); } } #[inline] unsafe fn choose_running_task() { // Safety: The precondition of this method includes CPU Lock being // active let mut lock = unsafe { utils::assume_cpu_lock::<Self>() }; task::choose_next_running_task(lock.borrow_mut()); // Post-condition: CPU Lock active forget(lock); } unsafe fn timer_tick() { timeout::handle_tick::<Self>(); } } /// Associates "system" types with kernel-private data. Use [`build!`] to /// implement. /// /// # Safety /// /// This is only intended to be implemented by `build!`. pub unsafe trait KernelCfg2: Port + Sized { // Most associated items are hidden because they have no use outside the // kernel. The rest is not hidden because it's meant to be accessed by port // code. #[doc(hiddden)] type TimeoutHeap: VecLike<Element = timeout::TimeoutRef<Self>> + Init + fmt::Debug + 'static; /// The table of combined second-level interrupt handlers. /// /// A port should generate first-level interrupt handlers that call them. const INTERRUPT_HANDLERS: &'static cfg::InterruptHandlerTable; #[doc(hidden)] const INTERRUPT_ATTR: InterruptAttr<Self>; #[doc(hidden)] const STARTUP_HOOKS: &'static [StartupHookAttr]; /// Access the kernel's global state. fn state() -> &'static State<Self>; #[doc(hidden)] fn hunk_pool_ptr() -> *mut u8; // FIXME: Waiting for <https://github.com/rust-lang/const-eval/issues/11> // to be resolved because `TaskCb` includes interior mutability // and can't be referred to by `const` #[doc(hidden)] fn task_cb_pool() -> &'static [TaskCb<Self>]; #[doc(hidden)] #[inline(always)] fn get_task_cb(i: usize) -> Option<&'static TaskCb<Self>> { Self::task_cb_pool().get(i) } // FIXME: Waiting for <https://github.com/rust-lang/const-eval/issues/11> // to be resolved because `EventGroupCb` includes interior mutability // and can't be referred to by `const` #[doc(hidden)] fn event_group_cb_pool() -> &'static [EventGroupCb<Self>]; #[doc(hidden)] #[inline(always)] fn get_event_group_cb(i: usize) -> Option<&'static EventGroupCb<Self>> { Self::event_group_cb_pool().get(i) } // FIXME: Waiting for <https://github.com/rust-lang/const-eval/issues/11> // to be resolved because `EventGroupCb` includes interior mutability // and can't be referred to by `const` #[doc(hidden)] fn mutex_cb_pool() -> &'static [MutexCb<Self>]; #[doc(hidden)] #[inline(always)] fn get_mutex_cb(i: usize) -> Option<&'static MutexCb<Self>> { Self::mutex_cb_pool().get(i) } // FIXME: Waiting for <https://github.com/rust-lang/const-eval/issues/11> // to be resolved because `EventGroupCb` includes interior mutability // and can't be referred to by `const` #[doc(hidden)] fn semaphore_cb_pool() -> &'static [SemaphoreCb<Self>]; #[doc(hidden)] #[inline(always)] fn get_semaphore_cb(i: usize) -> Option<&'static SemaphoreCb<Self>> { Self::semaphore_cb_pool().get(i) } // FIXME: Waiting for <https://github.com/rust-lang/const-eval/issues/11> // to be resolved because `TimerCb` includes interior mutability // and can't be referred to by `const` #[doc(hidden)] fn timer_cb_pool() -> &'static [TimerCb<Self>]; #[doc(hidden)] #[inline(always)] fn get_timer_cb(i: usize) -> Option<&'static TimerCb<Self>> { Self::timer_cb_pool().get(i) } } /// Global kernel state. pub struct State< System: KernelCfg2, PortTaskState: 'static = <System as PortThreading>::PortTaskState, TaskReadyQueue: 'static = <System as KernelCfg1>::TaskReadyQueue, TaskPriority: 'static = <System as KernelCfg1>::TaskPriority, TimeoutHeap: 'static = <System as KernelCfg2>::TimeoutHeap, > { /// The currently or recently running task. Can be in a Running, Waiting, or /// Ready state. The last two only can be observed momentarily around a /// call to `yield_cpu` or in an interrupt handler. running_task: utils::CpuLockCell<System, Option<&'static TaskCb<System, PortTaskState, TaskPriority>>>, /// The task ready queue. task_ready_queue: TaskReadyQueue, #[cfg(feature = "priority_boost")] /// `true` if Priority Boost is active. priority_boost: AtomicBool, /// The global state of the timekeeping system. timeout: timeout::TimeoutGlobals<System, TimeoutHeap>, } impl< System: KernelCfg2, PortTaskState: 'static, TaskReadyQueue: 'static + Init, TaskPriority: 'static, TimeoutHeap: 'static + Init, > Init for State<System, PortTaskState, TaskReadyQueue, TaskPriority, TimeoutHeap> { const INIT: Self = Self { running_task: utils::CpuLockCell::new(None), task_ready_queue: Init::INIT, #[cfg(feature = "priority_boost")] priority_boost: AtomicBool::new(false), timeout: Init::INIT, }; } impl< System: Kernel, PortTaskState: 'static + fmt::Debug, TaskReadyQueue: 'static + fmt::Debug, TaskPriority: 'static + fmt::Debug, TimeoutHeap: 'static + fmt::Debug, > fmt::Debug for State<System, PortTaskState, TaskReadyQueue, TaskPriority, TimeoutHeap> { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { f.debug_struct("State") .field("running_task", &self.running_task.get_and_debug_fmt()) .field("task_ready_queue", &self.task_ready_queue) .field( "priority_boost", match () { #[cfg(feature = "priority_boost")] () => &self.priority_boost, #[cfg(not(feature = "priority_boost"))] () => &(), }, ) .field("timeout", &self.timeout) .finish() } } impl<System: KernelCfg2> State<System> { /// Get the currently running task. #[inline] fn running_task( &self, lock: utils::CpuLockGuardBorrowMut<System>, ) -> Option<&'static TaskCb<System>> { *self.running_task.read(&*lock) } /// Get a pointer to the variable storing the currently running task. /// /// Reading the variable is safe as long as the read is free of data race. /// Note that only the dispatcher (that calls /// [`PortToKernel::choose_running_task`]) can modify the variable /// asynchonously. For example, it's safe to read it in a task context. It's /// also safe to read it in the dispatcher. On the other hand, reading it in /// a non-task context (except for the dispatcher, of course) may lead to /// an undefined behavior unless CPU Lock is activated while reading the /// variable. /// /// Writing the variable is not allowed. #[inline] pub fn running_task_ptr(&self) -> *mut Option<&'static TaskCb<System>> { self.running_task.as_ptr() } }