use std::cell::RefCell;
use std::collections::hash_map::Entry;
use std::convert::TryFrom;
+use std::rc::Rc;
use std::num::TryFromIntError;
use std::time::{Duration, Instant, SystemTime};
use rustc_data_structures::fx::FxHashMap;
use rustc_hir::def_id::DefId;
use rustc_index::vec::{Idx, IndexVec};
-use rustc_middle::{
- middle::codegen_fn_attrs::CodegenFnAttrFlags,
- mir,
- ty::{self, Instance},
-};
use crate::sync::SynchronizationState;
use crate::*;
/// responsibility of the synchronization primitives to track threads that
/// are blocked by them.
BlockedOnSync,
- /// The thread has terminated its execution (we do not delete terminated
- /// threads).
+ /// The thread has terminated its execution. We do not delete terminated
+ /// threads (FIXME: why?).
Terminated,
}
/// A thread.
pub struct Thread<'mir, 'tcx> {
state: ThreadState,
+
/// Name of the thread.
thread_name: Option<Vec<u8>>,
+
/// The virtual call stack.
stack: Vec<Frame<'mir, 'tcx, Tag, FrameData<'tcx>>>,
+
/// The join status.
join_status: ThreadJoinStatus,
+
+ /// The temporary used for storing the argument of
+ /// the call to `miri_start_panic` (the panic payload) when unwinding.
+ /// This is pointer-sized, and matches the `Payload` type in `src/libpanic_unwind/miri.rs`.
+ pub(crate) panic_payload: Option<Scalar<Tag>>,
+
+ /// Last OS error location in memory. It is a 32-bit integer.
+ pub(crate) last_error: Option<MPlaceTy<'tcx, Tag>>,
}
impl<'mir, 'tcx> Thread<'mir, 'tcx> {
thread_name: None,
stack: Vec::new(),
join_status: ThreadJoinStatus::Joinable,
+ panic_payload: None,
+ last_error: None,
}
}
}
+/// A specific moment in time.
#[derive(Debug)]
pub enum Time {
Monotonic(Instant),
fn set_thread_local_alloc_id(&self, def_id: DefId, new_alloc_id: AllocId) {
self.thread_local_alloc_ids
.borrow_mut()
- .insert((def_id, self.active_thread), new_alloc_id)
- .unwrap_none();
+ .try_insert((def_id, self.active_thread), new_alloc_id)
+ .unwrap();
}
/// Borrow the stack of the active thread.
}
/// Mark that the active thread tries to join the thread with `joined_thread_id`.
- fn join_thread(&mut self, joined_thread_id: ThreadId) -> InterpResult<'tcx> {
+ fn join_thread(&mut self, joined_thread_id: ThreadId, data_race: &Option<Rc<data_race::GlobalState>>) -> InterpResult<'tcx> {
if self.threads[joined_thread_id].join_status != ThreadJoinStatus::Joinable {
throw_ub_format!("trying to join a detached or already joined thread");
}
self.active_thread,
joined_thread_id
);
+ } else {
+ // The thread has already terminated - mark join happens-before
+ if let Some(data_race) = data_race {
+ data_race.thread_joined(self.active_thread, joined_thread_id);
+ }
}
Ok(())
}
/// Change the active thread to some enabled thread.
fn yield_active_thread(&mut self) {
+ // We do not yield immediately, as swapping out the current stack while executing a MIR statement
+ // could lead to all sorts of confusion.
+ // We should only switch stacks between steps.
self.yield_active_thread = true;
}
/// Register the given `callback` to be called once the `call_time` passes.
+ ///
+ /// The callback will be called with `thread` being the active thread, and
+ /// the callback may not change the active thread.
fn register_timeout_callback(
&mut self,
thread: ThreadId,
callback: TimeoutCallback<'mir, 'tcx>,
) {
self.timeout_callbacks
- .insert(thread, TimeoutCallbackInfo { call_time, callback })
- .unwrap_none();
+ .try_insert(thread, TimeoutCallbackInfo { call_time, callback })
+ .unwrap();
}
/// Unregister the callback for the `thread`.
None
}
+ /// Wakes up threads joining on the active one and deallocates thread-local statics.
+ /// The `AllocId` that can now be freed is returned.
+ fn thread_terminated(&mut self, data_race: &Option<Rc<data_race::GlobalState>>) -> Vec<AllocId> {
+ let mut free_tls_statics = Vec::new();
+ {
+ let mut thread_local_statics = self.thread_local_alloc_ids.borrow_mut();
+ thread_local_statics.retain(|&(_def_id, thread), &mut alloc_id| {
+ if thread != self.active_thread {
+ // Keep this static around.
+ return true;
+ }
+ // Delete this static from the map and from memory.
+ // We cannot free directly here as we cannot use `?` in this context.
+ free_tls_statics.push(alloc_id);
+ return false;
+ });
+ }
+ // Set the thread into a terminated state in the data-race detector
+ if let Some(data_race) = data_race {
+ data_race.thread_terminated();
+ }
+ // Check if we need to unblock any threads.
+ for (i, thread) in self.threads.iter_enumerated_mut() {
+ if thread.state == ThreadState::BlockedOnJoin(self.active_thread) {
+ // The thread has terminated, mark happens-before edge to joining thread
+ if let Some(data_race) = data_race {
+ data_race.thread_joined(i, self.active_thread);
+ }
+ trace!("unblocking {:?} because {:?} terminated", i, self.active_thread);
+ thread.state = ThreadState::Enabled;
+ }
+ }
+ return free_tls_statics;
+ }
+
/// Decide which action to take next and on which thread.
///
/// The currently implemented scheduling policy is the one that is commonly
/// used in stateless model checkers such as Loom: run the active thread as
/// long as we can and switch only when we have to (the active thread was
/// blocked, terminated, or has explicitly asked to be preempted).
- fn schedule(&mut self) -> InterpResult<'tcx, SchedulingAction> {
+ fn schedule(&mut self, data_race: &Option<Rc<data_race::GlobalState>>) -> InterpResult<'tcx, SchedulingAction> {
// Check whether the thread has **just** terminated (`check_terminated`
// checks whether the thread has popped all its stack and if yes, sets
// the thread state to terminated).
if self.threads[self.active_thread].check_terminated() {
- // Check if we need to unblock any threads.
- for (i, thread) in self.threads.iter_enumerated_mut() {
- if thread.state == ThreadState::BlockedOnJoin(self.active_thread) {
- trace!("unblocking {:?} because {:?} terminated", i, self.active_thread);
- thread.state = ThreadState::Enabled;
- }
- }
return Ok(SchedulingAction::ExecuteDtors);
}
+ // If we get here again and the thread is *still* terminated, there are no more dtors to run.
if self.threads[MAIN_THREAD].state == ThreadState::Terminated {
// The main thread terminated; stop the program.
if self.threads.iter().any(|thread| thread.state != ThreadState::Terminated) {
}
return Ok(SchedulingAction::Stop);
}
+ // This thread and the program can keep going.
if self.threads[self.active_thread].state == ThreadState::Enabled
&& !self.yield_active_thread
{
// The currently active thread is still enabled, just continue with it.
return Ok(SchedulingAction::ExecuteStep);
}
+ // The active thread yielded. Let's see if there are any timeouts to take care of. We do
+ // this *before* running any other thread, to ensure that timeouts "in the past" fire before
+ // any other thread can take an action. This ensures that for `pthread_cond_timedwait`, "an
+ // error is returned if [...] the absolute time specified by abstime has already been passed
+ // at the time of the call".
+ // <https://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_timedwait.html>
+ let potential_sleep_time =
+ self.timeout_callbacks.values().map(|info| info.call_time.get_wait_time()).min();
+ if potential_sleep_time == Some(Duration::new(0, 0)) {
+ return Ok(SchedulingAction::ExecuteTimeoutCallback);
+ }
+ // No callbacks scheduled, pick a regular thread to execute.
// We need to pick a new thread for execution.
for (id, thread) in self.threads.iter_enumerated() {
if thread.state == ThreadState::Enabled {
if !self.yield_active_thread || id != self.active_thread {
self.active_thread = id;
+ if let Some(data_race) = data_race {
+ data_race.thread_set_active(self.active_thread);
+ }
break;
}
}
// We have not found a thread to execute.
if self.threads.iter().all(|thread| thread.state == ThreadState::Terminated) {
unreachable!("all threads terminated without the main thread terminating?!");
- } else if let Some(sleep_time) =
- self.timeout_callbacks.values().map(|info| info.call_time.get_wait_time()).min()
- {
+ } else if let Some(sleep_time) = potential_sleep_time {
// All threads are currently blocked, but we have unexecuted
// timeout_callbacks, which may unblock some of the threads. Hence,
// sleep until the first callback.
// Public interface to thread management.
impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
- /// A workaround for thread-local statics until
- /// https://github.com/rust-lang/rust/issues/70685 is fixed: change the
- /// thread-local allocation id with a freshly generated allocation id for
- /// the currently active thread.
- fn remap_thread_local_alloc_ids(
- &self,
- val: &mut mir::interpret::ConstValue<'tcx>,
- ) -> InterpResult<'tcx> {
- let this = self.eval_context_ref();
- match *val {
- mir::interpret::ConstValue::Scalar(Scalar::Ptr(ref mut ptr)) => {
- let alloc_id = ptr.alloc_id;
- let alloc = this.tcx.get_global_alloc(alloc_id);
- let tcx = this.tcx;
- let is_thread_local = |def_id| {
- tcx.codegen_fn_attrs(def_id).flags.contains(CodegenFnAttrFlags::THREAD_LOCAL)
- };
- match alloc {
- Some(GlobalAlloc::Static(def_id)) if is_thread_local(def_id) => {
- ptr.alloc_id = this.get_or_create_thread_local_alloc_id(def_id)?;
- }
- _ => {}
- }
- }
- _ => {
- // FIXME: Handling only `Scalar` seems to work for now, but at
- // least in principle thread-locals could be in any constant, so
- // we should also consider other cases. However, once
- // https://github.com/rust-lang/rust/issues/70685 gets fixed,
- // this code will have to be rewritten anyway.
- }
- }
- Ok(())
- }
-
/// Get a thread-specific allocation id for the given thread-local static.
/// If needed, allocate a new one.
- ///
- /// FIXME: This method should be replaced as soon as
- /// https://github.com/rust-lang/rust/issues/70685 gets fixed.
- fn get_or_create_thread_local_alloc_id(&self, def_id: DefId) -> InterpResult<'tcx, AllocId> {
- let this = self.eval_context_ref();
+ fn get_or_create_thread_local_alloc_id(&mut self, def_id: DefId) -> InterpResult<'tcx, AllocId> {
+ let this = self.eval_context_mut();
let tcx = this.tcx;
if let Some(new_alloc_id) = this.machine.threads.get_thread_local_alloc_id(def_id) {
// We already have a thread-specific allocation id for this
} else {
// We need to allocate a thread-specific allocation id for this
// thread-local static.
- //
- // At first, we invoke the `const_eval_raw` query and extract the
- // allocation from it. Unfortunately, we have to duplicate the code
- // from `Memory::get_global_alloc` that does this.
- //
- // Then we store the retrieved allocation back into the `alloc_map`
- // to get a fresh allocation id, which we can use as a
- // thread-specific allocation id for the thread-local static.
+ // First, we compute the initial value for this static.
if tcx.is_foreign_item(def_id) {
throw_unsup_format!("foreign thread-local statics are not supported");
}
- // Invoke the `const_eval_raw` query.
- let instance = Instance::mono(tcx.tcx, def_id);
- let gid = GlobalId { instance, promoted: None };
- let raw_const =
- tcx.const_eval_raw(ty::ParamEnv::reveal_all().and(gid)).map_err(|err| {
- // no need to report anything, the const_eval call takes care of that
- // for statics
- assert!(tcx.is_static(def_id));
- err
- })?;
- let id = raw_const.alloc_id;
- // Extract the allocation from the query result.
- let allocation = tcx.global_alloc(id).unwrap_memory();
- // Create a new allocation id for the same allocation in this hacky
- // way. Internally, `alloc_map` deduplicates allocations, but this
- // is fine because Miri will make a copy before a first mutable
- // access.
- let new_alloc_id = tcx.create_memory_alloc(allocation);
+ let allocation = tcx.eval_static_initializer(def_id)?;
+ // Create a fresh allocation with this content.
+ let new_alloc_id = this.memory.allocate_with(allocation.clone(), MiriMemoryKind::Tls.into()).alloc_id;
this.machine.threads.set_thread_local_alloc_id(def_id, new_alloc_id);
Ok(new_alloc_id)
}
}
#[inline]
- fn create_thread(&mut self) -> InterpResult<'tcx, ThreadId> {
+ fn create_thread(&mut self) -> ThreadId {
let this = self.eval_context_mut();
- Ok(this.machine.threads.create_thread())
+ let id = this.machine.threads.create_thread();
+ if let Some(data_race) = &this.memory.extra.data_race {
+ data_race.thread_created(id);
+ }
+ id
}
#[inline]
#[inline]
fn join_thread(&mut self, joined_thread_id: ThreadId) -> InterpResult<'tcx> {
let this = self.eval_context_mut();
- this.machine.threads.join_thread(joined_thread_id)
+ let data_race = &this.memory.extra.data_race;
+ this.machine.threads.join_thread(joined_thread_id, data_race)?;
+ Ok(())
+ }
+
+ #[inline]
+ fn set_active_thread(&mut self, thread_id: ThreadId) -> ThreadId {
+ let this = self.eval_context_mut();
+ if let Some(data_race) = &this.memory.extra.data_race {
+ data_race.thread_set_active(thread_id);
+ }
+ this.machine.threads.set_active_thread_id(thread_id)
+ }
+
+ #[inline]
+ fn get_active_thread(&self) -> ThreadId {
+ let this = self.eval_context_ref();
+ this.machine.threads.get_active_thread_id()
}
#[inline]
- fn set_active_thread(&mut self, thread_id: ThreadId) -> InterpResult<'tcx, ThreadId> {
+ fn active_thread_mut(&mut self) -> &mut Thread<'mir, 'tcx> {
let this = self.eval_context_mut();
- Ok(this.machine.threads.set_active_thread_id(thread_id))
+ this.machine.threads.active_thread_mut()
}
#[inline]
- fn get_active_thread(&self) -> InterpResult<'tcx, ThreadId> {
+ fn active_thread_ref(&self) -> &Thread<'mir, 'tcx> {
let this = self.eval_context_ref();
- Ok(this.machine.threads.get_active_thread_id())
+ this.machine.threads.active_thread_ref()
}
#[inline]
- fn get_total_thread_count(&self) -> InterpResult<'tcx, usize> {
+ fn get_total_thread_count(&self) -> usize {
let this = self.eval_context_ref();
- Ok(this.machine.threads.get_total_thread_count())
+ this.machine.threads.get_total_thread_count()
}
#[inline]
- fn has_terminated(&self, thread_id: ThreadId) -> InterpResult<'tcx, bool> {
+ fn has_terminated(&self, thread_id: ThreadId) -> bool {
let this = self.eval_context_ref();
- Ok(this.machine.threads.has_terminated(thread_id))
+ this.machine.threads.has_terminated(thread_id)
}
#[inline]
- fn enable_thread(&mut self, thread_id: ThreadId) -> InterpResult<'tcx> {
+ fn enable_thread(&mut self, thread_id: ThreadId) {
let this = self.eval_context_mut();
this.machine.threads.enable_thread(thread_id);
- Ok(())
}
#[inline]
}
#[inline]
- fn set_active_thread_name(&mut self, new_thread_name: Vec<u8>) -> InterpResult<'tcx, ()> {
+ fn set_active_thread_name(&mut self, new_thread_name: Vec<u8>) {
let this = self.eval_context_mut();
- Ok(this.machine.threads.set_thread_name(new_thread_name))
+ if let Some(data_race) = &this.memory.extra.data_race {
+ if let Ok(string) = String::from_utf8(new_thread_name.clone()) {
+ data_race.thread_set_name(
+ this.machine.threads.active_thread, string
+ );
+ }
+ }
+ this.machine.threads.set_thread_name(new_thread_name);
}
#[inline]
- fn get_active_thread_name<'c>(&'c self) -> InterpResult<'tcx, &'c [u8]>
+ fn get_active_thread_name<'c>(&'c self) -> &'c [u8]
where
'mir: 'c,
{
let this = self.eval_context_ref();
- Ok(this.machine.threads.get_thread_name())
+ this.machine.threads.get_thread_name()
}
#[inline]
- fn block_thread(&mut self, thread: ThreadId) -> InterpResult<'tcx> {
+ fn block_thread(&mut self, thread: ThreadId) {
let this = self.eval_context_mut();
- Ok(this.machine.threads.block_thread(thread))
+ this.machine.threads.block_thread(thread);
}
#[inline]
- fn unblock_thread(&mut self, thread: ThreadId) -> InterpResult<'tcx> {
+ fn unblock_thread(&mut self, thread: ThreadId) {
let this = self.eval_context_mut();
- Ok(this.machine.threads.unblock_thread(thread))
+ this.machine.threads.unblock_thread(thread);
}
#[inline]
- fn yield_active_thread(&mut self) -> InterpResult<'tcx> {
+ fn yield_active_thread(&mut self) {
let this = self.eval_context_mut();
this.machine.threads.yield_active_thread();
- Ok(())
}
#[inline]
thread: ThreadId,
call_time: Time,
callback: TimeoutCallback<'mir, 'tcx>,
- ) -> InterpResult<'tcx> {
+ ) {
let this = self.eval_context_mut();
this.machine.threads.register_timeout_callback(thread, call_time, callback);
- Ok(())
}
#[inline]
- fn unregister_timeout_callback_if_exists(&mut self, thread: ThreadId) -> InterpResult<'tcx> {
+ fn unregister_timeout_callback_if_exists(&mut self, thread: ThreadId) {
let this = self.eval_context_mut();
this.machine.threads.unregister_timeout_callback_if_exists(thread);
- Ok(())
}
/// Execute a timeout callback on the callback's thread.
let this = self.eval_context_mut();
let (thread, callback) =
this.machine.threads.get_ready_callback().expect("no callback found");
- let old_thread = this.set_active_thread(thread)?;
+ // This back-and-forth with `set_active_thread` is here because of two
+ // design decisions:
+ // 1. Make the caller and not the callback responsible for changing
+ // thread.
+ // 2. Make the scheduler the only place that can change the active
+ // thread.
+ let old_thread = this.set_active_thread(thread);
callback(this)?;
- this.set_active_thread(old_thread)?;
+ this.set_active_thread(old_thread);
Ok(())
}
#[inline]
fn schedule(&mut self) -> InterpResult<'tcx, SchedulingAction> {
let this = self.eval_context_mut();
- this.machine.threads.schedule()
+ let data_race = &this.memory.extra.data_race;
+ this.machine.threads.schedule(data_race)
+ }
+
+ /// Handles thread termination of the active thread: wakes up threads joining on this one,
+ /// and deallocated thread-local statics.
+ ///
+ /// This is called from `tls.rs` after handling the TLS dtors.
+ #[inline]
+ fn thread_terminated(&mut self) -> InterpResult<'tcx> {
+ let this = self.eval_context_mut();
+ let data_race = &this.memory.extra.data_race;
+ for alloc_id in this.machine.threads.thread_terminated(data_race) {
+ let ptr = this.memory.global_base_pointer(alloc_id.into())?;
+ this.memory.deallocate(ptr, None, MiriMemoryKind::Tls.into())?;
+ }
+ Ok(())
}
}
projects / rust.git / blobdiff