//! Implement thread-local storage.
+use std::collections::btree_map::Entry as BTreeEntry;
+use std::collections::hash_map::Entry as HashMapEntry;
use std::collections::BTreeMap;
-use std::collections::btree_map::Entry;
-use std::collections::HashSet;
use log::trace;
+use rustc_data_structures::fx::FxHashMap;
use rustc_middle::ty;
-use rustc_target::abi::{Size, HasDataLayout};
+use rustc_target::abi::{HasDataLayout, Size};
+use rustc_target::spec::abi::Abi;
-use crate::{
- HelpersEvalContextExt, InterpResult, MPlaceTy, Scalar, StackPopCleanup, Tag, ThreadId,
- ThreadsEvalContextExt,
-};
+use crate::*;
pub type TlsKey = u128;
dtor: Option<ty::Instance<'tcx>>,
}
+#[derive(Clone, Debug)]
+struct RunningDtorsState {
+ /// The last TlsKey used to retrieve a TLS destructor. `None` means that we
+ /// have not tried to retrieve a TLS destructor yet or that we already tried
+ /// all keys.
+ last_dtor_key: Option<TlsKey>,
+}
+
#[derive(Debug)]
pub struct TlsData<'tcx> {
/// The Key to use for the next thread-local allocation.
/// A single per thread destructor of the thread local storage (that's how
/// things work on macOS) with a data argument.
- thread_dtors: BTreeMap<ThreadId, (ty::Instance<'tcx>, Scalar<Tag>)>,
-
- /// Whether we are in the "destruct" phase, during which some operations are UB.
- dtors_running: HashSet<ThreadId>,
+ macos_thread_dtors: BTreeMap<ThreadId, (ty::Instance<'tcx>, Scalar<Tag>)>,
- /// The last TlsKey used to retrieve a TLS destructor.
- last_dtor_key: BTreeMap<ThreadId, TlsKey>,
+ /// State for currently running TLS dtors. If this map contains a key for a
+ /// specific thread, it means that we are in the "destruct" phase, during
+ /// which some operations are UB.
+ dtors_running: FxHashMap<ThreadId, RunningDtorsState>,
}
impl<'tcx> Default for TlsData<'tcx> {
TlsData {
next_key: 1, // start with 1 as we must not use 0 on Windows
keys: Default::default(),
- thread_dtors: Default::default(),
+ macos_thread_dtors: Default::default(),
dtors_running: Default::default(),
- last_dtor_key: Default::default(),
}
}
}
impl<'tcx> TlsData<'tcx> {
/// Generate a new TLS key with the given destructor.
/// `max_size` determines the integer size the key has to fit in.
- pub fn create_tls_key(&mut self, dtor: Option<ty::Instance<'tcx>>, max_size: Size) -> InterpResult<'tcx, TlsKey> {
+ pub fn create_tls_key(
+ &mut self,
+ dtor: Option<ty::Instance<'tcx>>,
+ max_size: Size,
+ ) -> InterpResult<'tcx, TlsKey> {
let new_key = self.next_key;
self.next_key += 1;
- self.keys.insert(new_key, TlsEntry { data: Default::default(), dtor }).unwrap_none();
+ self.keys.try_insert(new_key, TlsEntry { data: Default::default(), dtor }).unwrap();
trace!("New TLS key allocated: {} with dtor {:?}", new_key, dtor);
if max_size.bits() < 128 && new_key >= (1u128 << max_size.bits() as u128) {
Some(TlsEntry { data, .. }) => {
let value = data.get(&thread_id).copied();
trace!("TLS key {} for thread {:?} loaded: {:?}", key, thread_id, value);
- Ok(value.unwrap_or_else(|| Scalar::null_ptr(cx).into()))
+ Ok(value.unwrap_or_else(|| Scalar::null_ptr(cx)))
}
None => throw_ub_format!("loading from a non-existing TLS key: {}", key),
}
&mut self,
key: TlsKey,
thread_id: ThreadId,
- new_data: Option<Scalar<Tag>>
+ new_data: Scalar<Tag>,
+ cx: &impl HasDataLayout,
) -> InterpResult<'tcx> {
match self.keys.get_mut(&key) {
Some(TlsEntry { data, .. }) => {
- match new_data {
- Some(scalar) => {
- trace!("TLS key {} for thread {:?} stored: {:?}", key, thread_id, scalar);
- data.insert(thread_id, scalar);
- }
- None => {
- trace!("TLS key {} for thread {:?} removed", key, thread_id);
- data.remove(&thread_id);
- }
+ if new_data.to_machine_usize(cx)? != 0 {
+ trace!("TLS key {} for thread {:?} stored: {:?}", key, thread_id, new_data);
+ data.insert(thread_id, new_data);
+ } else {
+ trace!("TLS key {} for thread {:?} removed", key, thread_id);
+ data.remove(&thread_id);
}
Ok(())
}
/// [`_tlv_atexit`
/// implementation](https://github.com/opensource-apple/dyld/blob/195030646877261f0c8c7ad8b001f52d6a26f514/src/threadLocalVariables.c#L389):
///
- /// // NOTE: this does not need locks because it only operates on current thread data
- pub fn set_thread_dtor(
+ /// NOTE: this does not need locks because it only operates on current thread data
+ pub fn set_macos_thread_dtor(
&mut self,
thread: ThreadId,
dtor: ty::Instance<'tcx>,
- data: Scalar<Tag>
+ data: Scalar<Tag>,
) -> InterpResult<'tcx> {
- if self.dtors_running.contains(&thread) {
+ if self.dtors_running.contains_key(&thread) {
// UB, according to libstd docs.
- throw_ub_format!("setting thread's local storage destructor while destructors are already running");
+ throw_ub_format!(
+ "setting thread's local storage destructor while destructors are already running"
+ );
}
- if self.thread_dtors.insert(thread, (dtor, data)).is_some() {
- throw_unsup_format!("setting more than one thread local storage destructor for the same thread is not supported");
+ if self.macos_thread_dtors.insert(thread, (dtor, data)).is_some() {
+ throw_unsup_format!(
+ "setting more than one thread local storage destructor for the same thread is not supported"
+ );
}
Ok(())
}
key: Option<TlsKey>,
thread_id: ThreadId,
) -> Option<(ty::Instance<'tcx>, Scalar<Tag>, TlsKey)> {
- use std::collections::Bound::*;
+ use std::ops::Bound::*;
let thread_local = &mut self.keys;
let start = match key {
Some(key) => Excluded(key),
None => Unbounded,
};
- for (&key, TlsEntry { data, dtor }) in
- thread_local.range_mut((start, Unbounded))
- {
+ for (&key, TlsEntry { data, dtor }) in thread_local.range_mut((start, Unbounded)) {
match data.entry(thread_id) {
- Entry::Occupied(entry) => {
+ BTreeEntry::Occupied(entry) => {
if let Some(dtor) = dtor {
+ // Set TLS data to NULL, and call dtor with old value.
let data_scalar = entry.remove();
let ret = Some((*dtor, data_scalar, key));
return ret;
}
}
- Entry::Vacant(_) => {}
+ BTreeEntry::Vacant(_) => {}
}
}
None
}
+
+ /// Set that dtors are running for `thread`. It is guaranteed not to change
+ /// the existing values stored in `dtors_running` for this thread. Returns
+ /// `true` if dtors for `thread` are already running.
+ fn set_dtors_running_for_thread(&mut self, thread: ThreadId) -> bool {
+ match self.dtors_running.entry(thread) {
+ HashMapEntry::Occupied(_) => true,
+ HashMapEntry::Vacant(entry) => {
+ // We cannot just do `self.dtors_running.insert` because that
+ // would overwrite `last_dtor_key` with `None`.
+ entry.insert(RunningDtorsState { last_dtor_key: None });
+ false
+ }
+ }
+ }
+
+ /// Delete all TLS entries for the given thread. This function should be
+ /// called after all TLS destructors have already finished.
+ fn delete_all_thread_tls(&mut self, thread_id: ThreadId) {
+ for TlsEntry { data, .. } in self.keys.values_mut() {
+ data.remove(&thread_id);
+ }
+ }
}
impl<'mir, 'tcx: 'mir> EvalContextPrivExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
/// yet.
fn schedule_windows_tls_dtors(&mut self) -> InterpResult<'tcx> {
let this = self.eval_context_mut();
- let active_thread = this.get_active_thread()?;
- assert_eq!(this.get_total_thread_count()?, 1, "concurrency on Windows not supported");
- this.machine.tls.dtors_running.insert(active_thread);
+ let active_thread = this.get_active_thread();
+ assert_eq!(this.get_total_thread_count(), 1, "concurrency on Windows is not supported");
// Windows has a special magic linker section that is run on certain events.
// Instead of searching for that section and supporting arbitrary hooks in there
// (that would be basically https://github.com/rust-lang/miri/issues/450),
// we specifically look up the static in libstd that we know is placed
// in that section.
- let thread_callback = this.eval_path_scalar(&["std", "sys", "windows", "thread_local", "p_thread_callback"])?;
- let thread_callback = this.memory.get_fn(thread_callback.not_undef()?)?.as_instance()?;
+ let thread_callback = this.eval_path_scalar(&[
+ "std",
+ "sys",
+ "windows",
+ "thread_local_key",
+ "p_thread_callback",
+ ])?;
+ let thread_callback =
+ this.get_ptr_fn(this.scalar_to_ptr(thread_callback)?)?.as_instance()?;
// The signature of this function is `unsafe extern "system" fn(h: c::LPVOID, dwReason: c::DWORD, pv: c::LPVOID)`.
- let reason = this.eval_path_scalar(&["std", "sys", "windows", "c", "DLL_PROCESS_DETACH"])?;
- let ret_place = MPlaceTy::dangling(this.machine.layouts.unit, this).into();
+ let reason = this.eval_path_scalar(&["std", "sys", "windows", "c", "DLL_THREAD_DETACH"])?;
+ let ret_place = MPlaceTy::dangling(this.machine.layouts.unit).into();
this.call_function(
thread_callback,
+ Abi::System { unwind: false },
&[Scalar::null_ptr(this).into(), reason.into(), Scalar::null_ptr(this).into()],
- Some(ret_place),
- StackPopCleanup::None { cleanup: true },
+ &ret_place,
+ StackPopCleanup::Root { cleanup: true },
)?;
- this.enable_thread(active_thread)?;
+ this.enable_thread(active_thread);
Ok(())
}
/// Schedule the MacOS thread destructor of the thread local storage to be
- /// executed.
+ /// executed. Returns `true` if scheduled.
///
/// Note: It is safe to call this function also on other Unixes.
- fn schedule_macos_tls_dtor(&mut self) -> InterpResult<'tcx> {
+ fn schedule_macos_tls_dtor(&mut self) -> InterpResult<'tcx, bool> {
let this = self.eval_context_mut();
- let thread_id = this.get_active_thread()?;
- if let Some((instance, data)) = this.machine.tls.thread_dtors.remove(&thread_id) {
+ let thread_id = this.get_active_thread();
+ if let Some((instance, data)) = this.machine.tls.macos_thread_dtors.remove(&thread_id) {
trace!("Running macos dtor {:?} on {:?} at {:?}", instance, data, thread_id);
- let ret_place = MPlaceTy::dangling(this.machine.layouts.unit, this).into();
+ let ret_place = MPlaceTy::dangling(this.machine.layouts.unit).into();
this.call_function(
instance,
+ Abi::C { unwind: false },
&[data.into()],
- Some(ret_place),
- StackPopCleanup::None { cleanup: true },
+ &ret_place,
+ StackPopCleanup::Root { cleanup: true },
)?;
// Enable the thread so that it steps through the destructor which
// we just scheduled. Since we deleted the destructor, it is
// guaranteed that we will schedule it again. The `dtors_running`
// flag will prevent the code from adding the destructor again.
- this.enable_thread(thread_id)?;
+ this.enable_thread(thread_id);
+ Ok(true)
+ } else {
+ Ok(false)
}
- Ok(())
}
- /// Schedule a pthread TLS destructor.
- fn schedule_pthread_tls_dtors(&mut self) -> InterpResult<'tcx> {
+ /// Schedule a pthread TLS destructor. Returns `true` if found
+ /// a destructor to schedule, and `false` otherwise.
+ fn schedule_next_pthread_tls_dtor(&mut self) -> InterpResult<'tcx, bool> {
let this = self.eval_context_mut();
- let active_thread = this.get_active_thread()?;
+ let active_thread = this.get_active_thread();
- assert!(this.has_terminated(active_thread)?, "running TLS dtors for non-terminated thread");
+ assert!(this.has_terminated(active_thread), "running TLS dtors for non-terminated thread");
// Fetch next dtor after `key`.
- let last_key = this.machine.tls.last_dtor_key.get(&active_thread).cloned();
+ let last_key = this.machine.tls.dtors_running[&active_thread].last_dtor_key;
let dtor = match this.machine.tls.fetch_tls_dtor(last_key, active_thread) {
dtor @ Some(_) => dtor,
// We ran each dtor once, start over from the beginning.
- None => {
- this.machine.tls.fetch_tls_dtor(None, active_thread)
- }
+ None => this.machine.tls.fetch_tls_dtor(None, active_thread),
};
if let Some((instance, ptr, key)) = dtor {
- this.machine.tls.last_dtor_key.insert(active_thread, key);
+ this.machine.tls.dtors_running.get_mut(&active_thread).unwrap().last_dtor_key =
+ Some(key);
trace!("Running TLS dtor {:?} on {:?} at {:?}", instance, ptr, active_thread);
- assert!(!this.is_null(ptr).unwrap(), "data can't be NULL when dtor is called!");
+ assert!(
+ !ptr.to_machine_usize(this).unwrap() != 0,
+ "data can't be NULL when dtor is called!"
+ );
- let ret_place = MPlaceTy::dangling(this.machine.layouts.unit, this).into();
+ let ret_place = MPlaceTy::dangling(this.machine.layouts.unit).into();
this.call_function(
instance,
+ Abi::C { unwind: false },
&[ptr.into()],
- Some(ret_place),
- StackPopCleanup::None { cleanup: true },
+ &ret_place,
+ StackPopCleanup::Root { cleanup: true },
)?;
- this.enable_thread(active_thread)?;
- return Ok(());
+ this.enable_thread(active_thread);
+ return Ok(true);
}
- this.machine.tls.last_dtor_key.remove(&active_thread);
+ this.machine.tls.dtors_running.get_mut(&active_thread).unwrap().last_dtor_key = None;
- Ok(())
+ Ok(false)
}
}
impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
-
/// Schedule an active thread's TLS destructor to run on the active thread.
/// Note that this function does not run the destructors itself, it just
/// schedules them one by one each time it is called and reenables the
/// thread so that it can be executed normally by the main execution loop.
///
- /// FIXME: we do not support yet deallocation of thread local statics.
- /// Issue: https://github.com/rust-lang/miri/issues/1369
+ /// Note: we consistently run TLS destructors for all threads, including the
+ /// main thread. However, it is not clear that we should run the TLS
+ /// destructors for the main thread. See issue:
+ /// <https://github.com/rust-lang/rust/issues/28129>.
fn schedule_next_tls_dtor_for_active_thread(&mut self) -> InterpResult<'tcx> {
let this = self.eval_context_mut();
- let active_thread = this.get_active_thread()?;
-
- if this.tcx.sess.target.target.target_os == "windows" {
- if !this.machine.tls.dtors_running.contains(&active_thread) {
- this.machine.tls.dtors_running.insert(active_thread);
+ let active_thread = this.get_active_thread();
+ trace!("schedule_next_tls_dtor_for_active_thread on thread {:?}", active_thread);
+
+ if !this.machine.tls.set_dtors_running_for_thread(active_thread) {
+ // This is the first time we got asked to schedule a destructor. The
+ // Windows schedule destructor function must be called exactly once,
+ // this is why it is in this block.
+ if this.tcx.sess.target.os == "windows" {
+ // On Windows, we signal that the thread quit by starting the
+ // relevant function, reenabling the thread, and going back to
+ // the scheduler.
this.schedule_windows_tls_dtors()?;
+ return Ok(());
}
- } else {
- this.machine.tls.dtors_running.insert(active_thread);
- // The macOS thread wide destructor runs "before any TLS slots get
- // freed", so do that first.
- this.schedule_macos_tls_dtor()?;
- this.schedule_pthread_tls_dtors()?;
}
+ // The remaining dtors make some progress each time around the scheduler loop,
+ // until they return `false` to indicate that they are done.
+
+ // The macOS thread wide destructor runs "before any TLS slots get
+ // freed", so do that first.
+ if this.schedule_macos_tls_dtor()? {
+ // We have scheduled a MacOS dtor to run on the thread. Execute it
+ // to completion and come back here. Scheduling a destructor
+ // destroys it, so we will not enter this branch again.
+ return Ok(());
+ }
+ if this.schedule_next_pthread_tls_dtor()? {
+ // We have scheduled a pthread destructor and removed it from the
+ // destructors list. Run it to completion and come back here.
+ return Ok(());
+ }
+
+ // All dtors done!
+ this.machine.tls.delete_all_thread_tls(active_thread);
+ this.thread_terminated()?;
Ok(())
}