| //! Implementation of a data-race detector using Lamport Timestamps / Vector-clocks |
| //! based on the Dynamic Race Detection for C++: |
| //! https://www.doc.ic.ac.uk/~afd/homepages/papers/pdfs/2017/POPL.pdf |
| //! which does not report false-positives when fences are used, and gives better |
| //! accuracy in presence of read-modify-write operations. |
| //! |
| //! The implementation contains modifications to correctly model the changes to the memory model in C++20 |
| //! regarding the weakening of release sequences: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0982r1.html. |
| //! Relaxed stores now unconditionally block all currently active release sequences and so per-thread tracking of release |
| //! sequences is not needed. |
| //! |
| //! This does not explore weak memory orders and so can still miss data-races |
| //! but should not report false-positives |
| //! |
| //! Data-race definition from(https://en.cppreference.com/w/cpp/language/memory_model#Threads_and_data_races): |
| //! a data race occurs between two memory accesses if they are on different threads, at least one operation |
| //! is non-atomic, at least one operation is a write and neither access happens-before the other. Read the link |
| //! for full definition. |
| //! |
| //! This re-uses vector indexes for threads that are known to be unable to report data-races, this is valid |
| //! because it only re-uses vector indexes once all currently-active (not-terminated) threads have an internal |
| //! vector clock that happens-after the join operation of the candidate thread. Threads that have not been joined |
| //! on are not considered. Since the thread's vector clock will only increase and a data-race implies that |
| //! there is some index x where clock[x] > thread_clock, when this is true clock[candidate-idx] > thread_clock |
| //! can never hold and hence a data-race can never be reported in that vector index again. |
| //! This means that the thread-index can be safely re-used, starting on the next timestamp for the newly created |
| //! thread. |
| //! |
| //! The sequentially consistent ordering corresponds to the ordering that the threads |
| //! are currently scheduled, this means that the data-race detector has no additional |
| //! logic for sequentially consistent accesses at the moment since they are indistinguishable |
| //! from acquire/release operations. If weak memory orderings are explored then this |
| //! may need to change or be updated accordingly. |
| //! |
| //! Per the C++ spec for the memory model a sequentially consistent operation: |
| //! "A load operation with this memory order performs an acquire operation, |
| //! a store performs a release operation, and read-modify-write performs |
| //! both an acquire operation and a release operation, plus a single total |
| //! order exists in which all threads observe all modifications in the same |
| //! order (see Sequentially-consistent ordering below) " |
| //! So in the absence of weak memory effects a seq-cst load & a seq-cst store is identical |
| //! to a acquire load and a release store given the global sequentially consistent order |
| //! of the schedule. |
| //! |
| //! The timestamps used in the data-race detector assign each sequence of non-atomic operations |
| //! followed by a single atomic or concurrent operation a single timestamp. |
| //! Write, Read, Write, ThreadJoin will be represented by a single timestamp value on a thread. |
| //! This is because extra increment operations between the operations in the sequence are not |
| //! required for accurate reporting of data-race values. |
| //! |
| //! As per the paper a threads timestamp is only incremented after a release operation is performed |
| //! so some atomic operations that only perform acquires do not increment the timestamp. Due to shared |
| //! code some atomic operations may increment the timestamp when not necessary but this has no effect |
| //! on the data-race detection code. |
| //! |
| //! FIXME: |
| //! currently we have our own local copy of the currently active thread index and names, this is due |
| //! in part to the inability to access the current location of threads.active_thread inside the AllocExtra |
| //! read, write and deallocate functions and should be cleaned up in the future. |
| |
| use std::{ |
| cell::{Cell, Ref, RefCell, RefMut}, |
| fmt::Debug, |
| mem, |
| rc::Rc, |
| }; |
| |
| use rustc_data_structures::fx::{FxHashMap, FxHashSet}; |
| use rustc_index::vec::{Idx, IndexVec}; |
| use rustc_middle::{mir, ty::layout::TyAndLayout}; |
| use rustc_target::abi::Size; |
| |
| use crate::{ |
| ImmTy, Immediate, InterpResult, MPlaceTy, MemPlaceMeta, MiriEvalContext, MiriEvalContextExt, |
| OpTy, Pointer, RangeMap, ScalarMaybeUninit, Tag, ThreadId, VClock, VTimestamp, |
| VectorIdx, |
| }; |
| |
| pub type AllocExtra = VClockAlloc; |
| pub type MemoryExtra = Rc<GlobalState>; |
| |
| /// Valid atomic read-write operations, alias of atomic::Ordering (not non-exhaustive). |
| #[derive(Copy, Clone, PartialEq, Eq, Debug)] |
| pub enum AtomicRwOp { |
| Relaxed, |
| Acquire, |
| Release, |
| AcqRel, |
| SeqCst, |
| } |
| |
| /// Valid atomic read operations, subset of atomic::Ordering. |
| #[derive(Copy, Clone, PartialEq, Eq, Debug)] |
| pub enum AtomicReadOp { |
| Relaxed, |
| Acquire, |
| SeqCst, |
| } |
| |
| /// Valid atomic write operations, subset of atomic::Ordering. |
| #[derive(Copy, Clone, PartialEq, Eq, Debug)] |
| pub enum AtomicWriteOp { |
| Relaxed, |
| Release, |
| SeqCst, |
| } |
| |
| /// Valid atomic fence operations, subset of atomic::Ordering. |
| #[derive(Copy, Clone, PartialEq, Eq, Debug)] |
| pub enum AtomicFenceOp { |
| Acquire, |
| Release, |
| AcqRel, |
| SeqCst, |
| } |
| |
| /// The current set of vector clocks describing the state |
| /// of a thread, contains the happens-before clock and |
| /// additional metadata to model atomic fence operations. |
| #[derive(Clone, Default, Debug)] |
| struct ThreadClockSet { |
| /// The increasing clock representing timestamps |
| /// that happen-before this thread. |
| clock: VClock, |
| |
| /// The set of timestamps that will happen-before this |
| /// thread once it performs an acquire fence. |
| fence_acquire: VClock, |
| |
| /// The last timestamp of happens-before relations that |
| /// have been released by this thread by a fence. |
| fence_release: VClock, |
| } |
| |
| impl ThreadClockSet { |
| /// Apply the effects of a release fence to this |
| /// set of thread vector clocks. |
| #[inline] |
| fn apply_release_fence(&mut self) { |
| self.fence_release.clone_from(&self.clock); |
| } |
| |
| /// Apply the effects of a acquire fence to this |
| /// set of thread vector clocks. |
| #[inline] |
| fn apply_acquire_fence(&mut self) { |
| self.clock.join(&self.fence_acquire); |
| } |
| |
| /// Increment the happens-before clock at a |
| /// known index. |
| #[inline] |
| fn increment_clock(&mut self, index: VectorIdx) { |
| self.clock.increment_index(index); |
| } |
| |
| /// Join the happens-before clock with that of |
| /// another thread, used to model thread join |
| /// operations. |
| fn join_with(&mut self, other: &ThreadClockSet) { |
| self.clock.join(&other.clock); |
| } |
| } |
| |
| /// Error returned by finding a data race |
| /// should be elaborated upon. |
| #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)] |
| pub struct DataRace; |
| |
| /// Externally stored memory cell clocks |
| /// explicitly to reduce memory usage for the |
| /// common case where no atomic operations |
| /// exists on the memory cell. |
| #[derive(Clone, PartialEq, Eq, Default, Debug)] |
| struct AtomicMemoryCellClocks { |
| /// The clock-vector of the timestamp of the last atomic |
| /// read operation performed by each thread. |
| /// This detects potential data-races between atomic read |
| /// and non-atomic write operations. |
| read_vector: VClock, |
| |
| /// The clock-vector of the timestamp of the last atomic |
| /// write operation performed by each thread. |
| /// This detects potential data-races between atomic write |
| /// and non-atomic read or write operations. |
| write_vector: VClock, |
| |
| /// Synchronization vector for acquire-release semantics |
| /// contains the vector of timestamps that will |
| /// happen-before a thread if an acquire-load is |
| /// performed on the data. |
| sync_vector: VClock, |
| } |
| |
| /// Memory Cell vector clock metadata |
| /// for data-race detection. |
| #[derive(Clone, PartialEq, Eq, Debug)] |
| struct MemoryCellClocks { |
| /// The vector-clock timestamp of the last write |
| /// corresponding to the writing threads timestamp. |
| write: VTimestamp, |
| |
| /// The identifier of the vector index, corresponding to a thread |
| /// that performed the last write operation. |
| write_index: VectorIdx, |
| |
| /// The vector-clock of the timestamp of the last read operation |
| /// performed by a thread since the last write operation occurred. |
| /// It is reset to zero on each write operation. |
| read: VClock, |
| |
| /// Atomic acquire & release sequence tracking clocks. |
| /// For non-atomic memory in the common case this |
| /// value is set to None. |
| atomic_ops: Option<Box<AtomicMemoryCellClocks>>, |
| } |
| |
| /// Create a default memory cell clocks instance |
| /// for uninitialized memory. |
| impl Default for MemoryCellClocks { |
| fn default() -> Self { |
| MemoryCellClocks { |
| read: VClock::default(), |
| write: 0, |
| write_index: VectorIdx::MAX_INDEX, |
| atomic_ops: None, |
| } |
| } |
| } |
| |
| impl MemoryCellClocks { |
| |
| /// Load the internal atomic memory cells if they exist. |
| #[inline] |
| fn atomic(&self) -> Option<&AtomicMemoryCellClocks> { |
| match &self.atomic_ops { |
| Some(op) => Some(&*op), |
| None => None, |
| } |
| } |
| |
| /// Load or create the internal atomic memory metadata |
| /// if it does not exist. |
| #[inline] |
| fn atomic_mut(&mut self) -> &mut AtomicMemoryCellClocks { |
| self.atomic_ops.get_or_insert_with(Default::default) |
| } |
| |
| /// Update memory cell data-race tracking for atomic |
| /// load acquire semantics, is a no-op if this memory was |
| /// not used previously as atomic memory. |
| fn load_acquire( |
| &mut self, |
| clocks: &mut ThreadClockSet, |
| index: VectorIdx, |
| ) -> Result<(), DataRace> { |
| self.atomic_read_detect(clocks, index)?; |
| if let Some(atomic) = self.atomic() { |
| clocks.clock.join(&atomic.sync_vector); |
| } |
| Ok(()) |
| } |
| |
| /// Update memory cell data-race tracking for atomic |
| /// load relaxed semantics, is a no-op if this memory was |
| /// not used previously as atomic memory. |
| fn load_relaxed( |
| &mut self, |
| clocks: &mut ThreadClockSet, |
| index: VectorIdx, |
| ) -> Result<(), DataRace> { |
| self.atomic_read_detect(clocks, index)?; |
| if let Some(atomic) = self.atomic() { |
| clocks.fence_acquire.join(&atomic.sync_vector); |
| } |
| Ok(()) |
| } |
| |
| /// Update the memory cell data-race tracking for atomic |
| /// store release semantics. |
| fn store_release(&mut self, clocks: &ThreadClockSet, index: VectorIdx) -> Result<(), DataRace> { |
| self.atomic_write_detect(clocks, index)?; |
| let atomic = self.atomic_mut(); |
| atomic.sync_vector.clone_from(&clocks.clock); |
| Ok(()) |
| } |
| |
| /// Update the memory cell data-race tracking for atomic |
| /// store relaxed semantics. |
| fn store_relaxed(&mut self, clocks: &ThreadClockSet, index: VectorIdx) -> Result<(), DataRace> { |
| self.atomic_write_detect(clocks, index)?; |
| |
| // The handling of release sequences was changed in C++20 and so |
| // the code here is different to the paper since now all relaxed |
| // stores block release sequences. The exception for same-thread |
| // relaxed stores has been removed. |
| let atomic = self.atomic_mut(); |
| atomic.sync_vector.clone_from(&clocks.fence_release); |
| Ok(()) |
| } |
| |
| /// Update the memory cell data-race tracking for atomic |
| /// store release semantics for RMW operations. |
| fn rmw_release(&mut self, clocks: &ThreadClockSet, index: VectorIdx) -> Result<(), DataRace> { |
| self.atomic_write_detect(clocks, index)?; |
| let atomic = self.atomic_mut(); |
| atomic.sync_vector.join(&clocks.clock); |
| Ok(()) |
| } |
| |
| /// Update the memory cell data-race tracking for atomic |
| /// store relaxed semantics for RMW operations. |
| fn rmw_relaxed(&mut self, clocks: &ThreadClockSet, index: VectorIdx) -> Result<(), DataRace> { |
| self.atomic_write_detect(clocks, index)?; |
| let atomic = self.atomic_mut(); |
| atomic.sync_vector.join(&clocks.fence_release); |
| Ok(()) |
| } |
| |
| /// Detect data-races with an atomic read, caused by a non-atomic write that does |
| /// not happen-before the atomic-read. |
| fn atomic_read_detect( |
| &mut self, |
| clocks: &ThreadClockSet, |
| index: VectorIdx, |
| ) -> Result<(), DataRace> { |
| log::trace!("Atomic read with vectors: {:#?} :: {:#?}", self, clocks); |
| if self.write <= clocks.clock[self.write_index] { |
| let atomic = self.atomic_mut(); |
| atomic.read_vector.set_at_index(&clocks.clock, index); |
| Ok(()) |
| } else { |
| Err(DataRace) |
| } |
| } |
| |
| /// Detect data-races with an atomic write, either with a non-atomic read or with |
| /// a non-atomic write. |
| fn atomic_write_detect( |
| &mut self, |
| clocks: &ThreadClockSet, |
| index: VectorIdx, |
| ) -> Result<(), DataRace> { |
| log::trace!("Atomic write with vectors: {:#?} :: {:#?}", self, clocks); |
| if self.write <= clocks.clock[self.write_index] && self.read <= clocks.clock { |
| let atomic = self.atomic_mut(); |
| atomic.write_vector.set_at_index(&clocks.clock, index); |
| Ok(()) |
| } else { |
| Err(DataRace) |
| } |
| } |
| |
| /// Detect races for non-atomic read operations at the current memory cell |
| /// returns true if a data-race is detected. |
| fn read_race_detect( |
| &mut self, |
| clocks: &ThreadClockSet, |
| index: VectorIdx, |
| ) -> Result<(), DataRace> { |
| log::trace!("Unsynchronized read with vectors: {:#?} :: {:#?}", self, clocks); |
| if self.write <= clocks.clock[self.write_index] { |
| let race_free = if let Some(atomic) = self.atomic() { |
| atomic.write_vector <= clocks.clock |
| } else { |
| true |
| }; |
| if race_free { |
| self.read.set_at_index(&clocks.clock, index); |
| Ok(()) |
| } else { |
| Err(DataRace) |
| } |
| } else { |
| Err(DataRace) |
| } |
| } |
| |
| /// Detect races for non-atomic write operations at the current memory cell |
| /// returns true if a data-race is detected. |
| fn write_race_detect( |
| &mut self, |
| clocks: &ThreadClockSet, |
| index: VectorIdx, |
| ) -> Result<(), DataRace> { |
| log::trace!("Unsynchronized write with vectors: {:#?} :: {:#?}", self, clocks); |
| if self.write <= clocks.clock[self.write_index] && self.read <= clocks.clock { |
| let race_free = if let Some(atomic) = self.atomic() { |
| atomic.write_vector <= clocks.clock && atomic.read_vector <= clocks.clock |
| } else { |
| true |
| }; |
| if race_free { |
| self.write = clocks.clock[index]; |
| self.write_index = index; |
| self.read.set_zero_vector(); |
| Ok(()) |
| } else { |
| Err(DataRace) |
| } |
| } else { |
| Err(DataRace) |
| } |
| } |
| } |
| |
| /// Evaluation context extensions. |
| impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for MiriEvalContext<'mir, 'tcx> {} |
| pub trait EvalContextExt<'mir, 'tcx: 'mir>: MiriEvalContextExt<'mir, 'tcx> { |
| /// Atomic variant of read_scalar_at_offset. |
| fn read_scalar_at_offset_atomic( |
| &self, |
| op: OpTy<'tcx, Tag>, |
| offset: u64, |
| layout: TyAndLayout<'tcx>, |
| atomic: AtomicReadOp, |
| ) -> InterpResult<'tcx, ScalarMaybeUninit<Tag>> { |
| let this = self.eval_context_ref(); |
| let op_place = this.deref_operand(op)?; |
| let offset = Size::from_bytes(offset); |
| |
| // Ensure that the following read at an offset is within bounds. |
| assert!(op_place.layout.size >= offset + layout.size); |
| let value_place = op_place.offset(offset, MemPlaceMeta::None, layout, this)?; |
| this.read_scalar_atomic(value_place, atomic) |
| } |
| |
| /// Atomic variant of write_scalar_at_offset. |
| fn write_scalar_at_offset_atomic( |
| &mut self, |
| op: OpTy<'tcx, Tag>, |
| offset: u64, |
| value: impl Into<ScalarMaybeUninit<Tag>>, |
| layout: TyAndLayout<'tcx>, |
| atomic: AtomicWriteOp, |
| ) -> InterpResult<'tcx> { |
| let this = self.eval_context_mut(); |
| let op_place = this.deref_operand(op)?; |
| let offset = Size::from_bytes(offset); |
| |
| // Ensure that the following read at an offset is within bounds. |
| assert!(op_place.layout.size >= offset + layout.size); |
| let value_place = op_place.offset(offset, MemPlaceMeta::None, layout, this)?; |
| this.write_scalar_atomic(value.into(), value_place, atomic) |
| } |
| |
| /// Perform an atomic read operation at the memory location. |
| fn read_scalar_atomic( |
| &self, |
| place: MPlaceTy<'tcx, Tag>, |
| atomic: AtomicReadOp, |
| ) -> InterpResult<'tcx, ScalarMaybeUninit<Tag>> { |
| let this = self.eval_context_ref(); |
| let scalar = this.allow_data_races_ref(move |this| this.read_scalar(place.into()))?; |
| self.validate_atomic_load(place, atomic)?; |
| Ok(scalar) |
| } |
| |
| /// Perform an atomic write operation at the memory location. |
| fn write_scalar_atomic( |
| &mut self, |
| val: ScalarMaybeUninit<Tag>, |
| dest: MPlaceTy<'tcx, Tag>, |
| atomic: AtomicWriteOp, |
| ) -> InterpResult<'tcx> { |
| let this = self.eval_context_mut(); |
| this.allow_data_races_mut(move |this| this.write_scalar(val, dest.into()))?; |
| self.validate_atomic_store(dest, atomic) |
| } |
| |
| /// Perform a atomic operation on a memory location. |
| fn atomic_op_immediate( |
| &mut self, |
| place: MPlaceTy<'tcx, Tag>, |
| rhs: ImmTy<'tcx, Tag>, |
| op: mir::BinOp, |
| neg: bool, |
| atomic: AtomicRwOp, |
| ) -> InterpResult<'tcx, ImmTy<'tcx, Tag>> { |
| let this = self.eval_context_mut(); |
| |
| let old = this.allow_data_races_mut(|this| this.read_immediate(place.into()))?; |
| |
| // Atomics wrap around on overflow. |
| let val = this.binary_op(op, old, rhs)?; |
| let val = if neg { this.unary_op(mir::UnOp::Not, val)? } else { val }; |
| this.allow_data_races_mut(|this| this.write_immediate(*val, place.into()))?; |
| |
| this.validate_atomic_rmw(place, atomic)?; |
| Ok(old) |
| } |
| |
| /// Perform an atomic exchange with a memory place and a new |
| /// scalar value, the old value is returned. |
| fn atomic_exchange_scalar( |
| &mut self, |
| place: MPlaceTy<'tcx, Tag>, |
| new: ScalarMaybeUninit<Tag>, |
| atomic: AtomicRwOp, |
| ) -> InterpResult<'tcx, ScalarMaybeUninit<Tag>> { |
| let this = self.eval_context_mut(); |
| |
| let old = this.allow_data_races_mut(|this| this.read_scalar(place.into()))?; |
| this.allow_data_races_mut(|this| this.write_scalar(new, place.into()))?; |
| this.validate_atomic_rmw(place, atomic)?; |
| Ok(old) |
| } |
| |
| /// Perform an atomic compare and exchange at a given memory location. |
| /// On success an atomic RMW operation is performed and on failure |
| /// only an atomic read occurs. |
| fn atomic_compare_exchange_scalar( |
| &mut self, |
| place: MPlaceTy<'tcx, Tag>, |
| expect_old: ImmTy<'tcx, Tag>, |
| new: ScalarMaybeUninit<Tag>, |
| success: AtomicRwOp, |
| fail: AtomicReadOp, |
| ) -> InterpResult<'tcx, Immediate<Tag>> { |
| let this = self.eval_context_mut(); |
| |
| // Failure ordering cannot be stronger than success ordering, therefore first attempt |
| // to read with the failure ordering and if successful then try again with the success |
| // read ordering and write in the success case. |
| // Read as immediate for the sake of `binary_op()` |
| let old = this.allow_data_races_mut(|this| this.read_immediate(place.into()))?; |
| |
| // `binary_op` will bail if either of them is not a scalar. |
| let eq = this.overflowing_binary_op(mir::BinOp::Eq, old, expect_old)?.0; |
| let res = Immediate::ScalarPair(old.to_scalar_or_uninit(), eq.into()); |
| |
| // Update ptr depending on comparison. |
| // if successful, perform a full rw-atomic validation |
| // otherwise treat this as an atomic load with the fail ordering. |
| if eq.to_bool()? { |
| this.allow_data_races_mut(|this| this.write_scalar(new, place.into()))?; |
| this.validate_atomic_rmw(place, success)?; |
| } else { |
| this.validate_atomic_load(place, fail)?; |
| } |
| |
| // Return the old value. |
| Ok(res) |
| } |
| |
| /// Update the data-race detector for an atomic read occurring at the |
| /// associated memory-place and on the current thread. |
| fn validate_atomic_load( |
| &self, |
| place: MPlaceTy<'tcx, Tag>, |
| atomic: AtomicReadOp, |
| ) -> InterpResult<'tcx> { |
| let this = self.eval_context_ref(); |
| this.validate_atomic_op( |
| place, |
| atomic, |
| "Atomic Load", |
| move |memory, clocks, index, atomic| { |
| if atomic == AtomicReadOp::Relaxed { |
| memory.load_relaxed(&mut *clocks, index) |
| } else { |
| memory.load_acquire(&mut *clocks, index) |
| } |
| }, |
| ) |
| } |
| |
| /// Update the data-race detector for an atomic write occurring at the |
| /// associated memory-place and on the current thread. |
| fn validate_atomic_store( |
| &mut self, |
| place: MPlaceTy<'tcx, Tag>, |
| atomic: AtomicWriteOp, |
| ) -> InterpResult<'tcx> { |
| let this = self.eval_context_ref(); |
| this.validate_atomic_op( |
| place, |
| atomic, |
| "Atomic Store", |
| move |memory, clocks, index, atomic| { |
| if atomic == AtomicWriteOp::Relaxed { |
| memory.store_relaxed(clocks, index) |
| } else { |
| memory.store_release(clocks, index) |
| } |
| }, |
| ) |
| } |
| |
| /// Update the data-race detector for an atomic read-modify-write occurring |
| /// at the associated memory place and on the current thread. |
| fn validate_atomic_rmw( |
| &mut self, |
| place: MPlaceTy<'tcx, Tag>, |
| atomic: AtomicRwOp, |
| ) -> InterpResult<'tcx> { |
| use AtomicRwOp::*; |
| let acquire = matches!(atomic, Acquire | AcqRel | SeqCst); |
| let release = matches!(atomic, Release | AcqRel | SeqCst); |
| let this = self.eval_context_ref(); |
| this.validate_atomic_op(place, atomic, "Atomic RMW", move |memory, clocks, index, _| { |
| if acquire { |
| memory.load_acquire(clocks, index)?; |
| } else { |
| memory.load_relaxed(clocks, index)?; |
| } |
| if release { |
| memory.rmw_release(clocks, index) |
| } else { |
| memory.rmw_relaxed(clocks, index) |
| } |
| }) |
| } |
| |
| /// Update the data-race detector for an atomic fence on the current thread. |
| fn validate_atomic_fence(&mut self, atomic: AtomicFenceOp) -> InterpResult<'tcx> { |
| let this = self.eval_context_mut(); |
| if let Some(data_race) = &this.memory.extra.data_race { |
| data_race.maybe_perform_sync_operation(move |index, mut clocks| { |
| log::trace!("Atomic fence on {:?} with ordering {:?}", index, atomic); |
| |
| // Apply data-race detection for the current fences |
| // this treats AcqRel and SeqCst as the same as a acquire |
| // and release fence applied in the same timestamp. |
| if atomic != AtomicFenceOp::Release { |
| // Either Acquire | AcqRel | SeqCst |
| clocks.apply_acquire_fence(); |
| } |
| if atomic != AtomicFenceOp::Acquire { |
| // Either Release | AcqRel | SeqCst |
| clocks.apply_release_fence(); |
| } |
| |
| // Increment timestamp in case of release semantics. |
| Ok(atomic != AtomicFenceOp::Acquire) |
| }) |
| } else { |
| Ok(()) |
| } |
| } |
| } |
| |
| /// Vector clock metadata for a logical memory allocation. |
| #[derive(Debug, Clone)] |
| pub struct VClockAlloc { |
| /// Assigning each byte a MemoryCellClocks. |
| alloc_ranges: RefCell<RangeMap<MemoryCellClocks>>, |
| |
| // Pointer to global state. |
| global: MemoryExtra, |
| } |
| |
| impl VClockAlloc { |
| /// Create a new data-race allocation detector. |
| pub fn new_allocation(global: &MemoryExtra, len: Size) -> VClockAlloc { |
| VClockAlloc { |
| global: Rc::clone(global), |
| alloc_ranges: RefCell::new(RangeMap::new(len, MemoryCellClocks::default())), |
| } |
| } |
| |
| // Find an index, if one exists where the value |
| // in `l` is greater than the value in `r`. |
| fn find_gt_index(l: &VClock, r: &VClock) -> Option<VectorIdx> { |
| let l_slice = l.as_slice(); |
| let r_slice = r.as_slice(); |
| l_slice |
| .iter() |
| .zip(r_slice.iter()) |
| .enumerate() |
| .find_map(|(idx, (&l, &r))| if l > r { Some(idx) } else { None }) |
| .or_else(|| { |
| if l_slice.len() > r_slice.len() { |
| // By invariant, if l_slice is longer |
| // then one element must be larger. |
| // This just validates that this is true |
| // and reports earlier elements first. |
| let l_remainder_slice = &l_slice[r_slice.len()..]; |
| let idx = l_remainder_slice |
| .iter() |
| .enumerate() |
| .find_map(|(idx, &r)| if r == 0 { None } else { Some(idx) }) |
| .expect("Invalid VClock Invariant"); |
| Some(idx) |
| } else { |
| None |
| } |
| }) |
| .map(|idx| VectorIdx::new(idx)) |
| } |
| |
| /// Report a data-race found in the program. |
| /// This finds the two racing threads and the type |
| /// of data-race that occurred. This will also |
| /// return info about the memory location the data-race |
| /// occurred in. |
| #[cold] |
| #[inline(never)] |
| fn report_data_race<'tcx>( |
| global: &MemoryExtra, |
| range: &MemoryCellClocks, |
| action: &str, |
| is_atomic: bool, |
| pointer: Pointer<Tag>, |
| len: Size, |
| ) -> InterpResult<'tcx> { |
| let (current_index, current_clocks) = global.current_thread_state(); |
| let write_clock; |
| let (other_action, other_thread, other_clock) = if range.write |
| > current_clocks.clock[range.write_index] |
| { |
| // Convert the write action into the vector clock it |
| // represents for diagnostic purposes. |
| write_clock = VClock::new_with_index(range.write_index, range.write); |
| ("WRITE", range.write_index, &write_clock) |
| } else if let Some(idx) = Self::find_gt_index(&range.read, ¤t_clocks.clock) { |
| ("READ", idx, &range.read) |
| } else if !is_atomic { |
| if let Some(atomic) = range.atomic() { |
| if let Some(idx) = Self::find_gt_index(&atomic.write_vector, ¤t_clocks.clock) |
| { |
| ("ATOMIC_STORE", idx, &atomic.write_vector) |
| } else if let Some(idx) = |
| Self::find_gt_index(&atomic.read_vector, ¤t_clocks.clock) |
| { |
| ("ATOMIC_LOAD", idx, &atomic.read_vector) |
| } else { |
| unreachable!( |
| "Failed to report data-race for non-atomic operation: no race found" |
| ) |
| } |
| } else { |
| unreachable!( |
| "Failed to report data-race for non-atomic operation: no atomic component" |
| ) |
| } |
| } else { |
| unreachable!("Failed to report data-race for atomic operation") |
| }; |
| |
| // Load elaborated thread information about the racing thread actions. |
| let current_thread_info = global.print_thread_metadata(current_index); |
| let other_thread_info = global.print_thread_metadata(other_thread); |
| |
| // Throw the data-race detection. |
| throw_ub_format!( |
| "Data race detected between {} on {} and {} on {}, memory({:?},offset={},size={})\ |
| \n\t\t -current vector clock = {:?}\ |
| \n\t\t -conflicting timestamp = {:?}", |
| action, |
| current_thread_info, |
| other_action, |
| other_thread_info, |
| pointer.alloc_id, |
| pointer.offset.bytes(), |
| len.bytes(), |
| current_clocks.clock, |
| other_clock |
| ) |
| } |
| |
| /// Detect data-races for an unsynchronized read operation, will not perform |
| /// data-race detection if `multi-threaded` is false, either due to no threads |
| /// being created or if it is temporarily disabled during a racy read or write |
| /// operation for which data-race detection is handled separately, for example |
| /// atomic read operations. |
| pub fn read<'tcx>(&self, pointer: Pointer<Tag>, len: Size) -> InterpResult<'tcx> { |
| if self.global.multi_threaded.get() { |
| let (index, clocks) = self.global.current_thread_state(); |
| let mut alloc_ranges = self.alloc_ranges.borrow_mut(); |
| for (_, range) in alloc_ranges.iter_mut(pointer.offset, len) { |
| if let Err(DataRace) = range.read_race_detect(&*clocks, index) { |
| // Report data-race. |
| return Self::report_data_race( |
| &self.global, |
| range, |
| "READ", |
| false, |
| pointer, |
| len, |
| ); |
| } |
| } |
| Ok(()) |
| } else { |
| Ok(()) |
| } |
| } |
| |
| // Shared code for detecting data-races on unique access to a section of memory |
| fn unique_access<'tcx>( |
| &mut self, |
| pointer: Pointer<Tag>, |
| len: Size, |
| action: &str, |
| ) -> InterpResult<'tcx> { |
| if self.global.multi_threaded.get() { |
| let (index, clocks) = self.global.current_thread_state(); |
| for (_, range) in self.alloc_ranges.get_mut().iter_mut(pointer.offset, len) { |
| if let Err(DataRace) = range.write_race_detect(&*clocks, index) { |
| // Report data-race |
| return Self::report_data_race( |
| &self.global, |
| range, |
| action, |
| false, |
| pointer, |
| len, |
| ); |
| } |
| } |
| Ok(()) |
| } else { |
| Ok(()) |
| } |
| } |
| |
| /// Detect data-races for an unsynchronized write operation, will not perform |
| /// data-race threads if `multi-threaded` is false, either due to no threads |
| /// being created or if it is temporarily disabled during a racy read or write |
| /// operation |
| pub fn write<'tcx>(&mut self, pointer: Pointer<Tag>, len: Size) -> InterpResult<'tcx> { |
| self.unique_access(pointer, len, "Write") |
| } |
| |
| /// Detect data-races for an unsynchronized deallocate operation, will not perform |
| /// data-race threads if `multi-threaded` is false, either due to no threads |
| /// being created or if it is temporarily disabled during a racy read or write |
| /// operation |
| pub fn deallocate<'tcx>(&mut self, pointer: Pointer<Tag>, len: Size) -> InterpResult<'tcx> { |
| self.unique_access(pointer, len, "Deallocate") |
| } |
| } |
| |
| impl<'mir, 'tcx: 'mir> EvalContextPrivExt<'mir, 'tcx> for MiriEvalContext<'mir, 'tcx> {} |
| trait EvalContextPrivExt<'mir, 'tcx: 'mir>: MiriEvalContextExt<'mir, 'tcx> { |
| // Temporarily allow data-races to occur, this should only be |
| // used if either one of the appropriate `validate_atomic` functions |
| // will be called to treat a memory access as atomic or if the memory |
| // being accessed should be treated as internal state, that cannot be |
| // accessed by the interpreted program. |
| #[inline] |
| fn allow_data_races_ref<R>(&self, op: impl FnOnce(&MiriEvalContext<'mir, 'tcx>) -> R) -> R { |
| let this = self.eval_context_ref(); |
| let old = if let Some(data_race) = &this.memory.extra.data_race { |
| data_race.multi_threaded.replace(false) |
| } else { |
| false |
| }; |
| let result = op(this); |
| if let Some(data_race) = &this.memory.extra.data_race { |
| data_race.multi_threaded.set(old); |
| } |
| result |
| } |
| |
| /// Same as `allow_data_races_ref`, this temporarily disables any data-race detection and |
| /// so should only be used for atomic operations or internal state that the program cannot |
| /// access. |
| #[inline] |
| fn allow_data_races_mut<R>( |
| &mut self, |
| op: impl FnOnce(&mut MiriEvalContext<'mir, 'tcx>) -> R, |
| ) -> R { |
| let this = self.eval_context_mut(); |
| let old = if let Some(data_race) = &this.memory.extra.data_race { |
| data_race.multi_threaded.replace(false) |
| } else { |
| false |
| }; |
| let result = op(this); |
| if let Some(data_race) = &this.memory.extra.data_race { |
| data_race.multi_threaded.set(old); |
| } |
| result |
| } |
| |
| /// Generic atomic operation implementation, |
| /// this accesses memory via get_raw instead of |
| /// get_raw_mut, due to issues calling get_raw_mut |
| /// for atomic loads from read-only memory. |
| /// FIXME: is this valid, or should get_raw_mut be used for |
| /// atomic-stores/atomic-rmw? |
| fn validate_atomic_op<A: Debug + Copy>( |
| &self, |
| place: MPlaceTy<'tcx, Tag>, |
| atomic: A, |
| description: &str, |
| mut op: impl FnMut( |
| &mut MemoryCellClocks, |
| &mut ThreadClockSet, |
| VectorIdx, |
| A, |
| ) -> Result<(), DataRace>, |
| ) -> InterpResult<'tcx> { |
| let this = self.eval_context_ref(); |
| if let Some(data_race) = &this.memory.extra.data_race { |
| if data_race.multi_threaded.get() { |
| // Load and log the atomic operation. |
| let place_ptr = place.ptr.assert_ptr(); |
| let size = place.layout.size; |
| let alloc_meta = |
| &this.memory.get_raw(place_ptr.alloc_id)?.extra.data_race.as_ref().unwrap(); |
| log::trace!( |
| "Atomic op({}) with ordering {:?} on memory({:?}, offset={}, size={})", |
| description, |
| &atomic, |
| place_ptr.alloc_id, |
| place_ptr.offset.bytes(), |
| size.bytes() |
| ); |
| |
| // Perform the atomic operation. |
| let data_race = &alloc_meta.global; |
| data_race.maybe_perform_sync_operation(|index, mut clocks| { |
| for (_, range) in |
| alloc_meta.alloc_ranges.borrow_mut().iter_mut(place_ptr.offset, size) |
| { |
| if let Err(DataRace) = op(range, &mut *clocks, index, atomic) { |
| mem::drop(clocks); |
| return VClockAlloc::report_data_race( |
| &alloc_meta.global, |
| range, |
| description, |
| true, |
| place_ptr, |
| size, |
| ).map(|_| true); |
| } |
| } |
| |
| // This conservatively assumes all operations have release semantics |
| Ok(true) |
| })?; |
| |
| // Log changes to atomic memory. |
| if log::log_enabled!(log::Level::Trace) { |
| for (_, range) in alloc_meta.alloc_ranges.borrow().iter(place_ptr.offset, size) |
| { |
| log::trace!( |
| "Updated atomic memory({:?}, offset={}, size={}) to {:#?}", |
| place.ptr.assert_ptr().alloc_id, |
| place_ptr.offset.bytes(), |
| size.bytes(), |
| range.atomic_ops |
| ); |
| } |
| } |
| } |
| } |
| Ok(()) |
| } |
| } |
| |
| /// Extra metadata associated with a thread. |
| #[derive(Debug, Clone, Default)] |
| struct ThreadExtraState { |
| /// The current vector index in use by the |
| /// thread currently, this is set to None |
| /// after the vector index has been re-used |
| /// and hence the value will never need to be |
| /// read during data-race reporting. |
| vector_index: Option<VectorIdx>, |
| |
| /// The name of the thread, updated for better |
| /// diagnostics when reporting detected data |
| /// races. |
| thread_name: Option<Box<str>>, |
| |
| /// Thread termination vector clock, this |
| /// is set on thread termination and is used |
| /// for joining on threads since the vector_index |
| /// may be re-used when the join operation occurs. |
| termination_vector_clock: Option<VClock>, |
| } |
| |
| /// Global data-race detection state, contains the currently |
| /// executing thread as well as the vector-clocks associated |
| /// with each of the threads. |
| #[derive(Debug, Clone)] |
| pub struct GlobalState { |
| /// Set to true once the first additional |
| /// thread has launched, due to the dependency |
| /// between before and after a thread launch. |
| /// Any data-races must be recorded after this |
| /// so concurrent execution can ignore recording |
| /// any data-races. |
| multi_threaded: Cell<bool>, |
| |
| /// Mapping of a vector index to a known set of thread |
| /// clocks, this is not directly mapping from a thread id |
| /// since it may refer to multiple threads. |
| vector_clocks: RefCell<IndexVec<VectorIdx, ThreadClockSet>>, |
| |
| /// Mapping of a given vector index to the current thread |
| /// that the execution is representing, this may change |
| /// if a vector index is re-assigned to a new thread. |
| vector_info: RefCell<IndexVec<VectorIdx, ThreadId>>, |
| |
| /// The mapping of a given thread to associated thread metadata. |
| thread_info: RefCell<IndexVec<ThreadId, ThreadExtraState>>, |
| |
| /// The current vector index being executed. |
| current_index: Cell<VectorIdx>, |
| |
| /// Potential vector indices that could be re-used on thread creation |
| /// values are inserted here on after the thread has terminated and |
| /// been joined with, and hence may potentially become free |
| /// for use as the index for a new thread. |
| /// Elements in this set may still require the vector index to |
| /// report data-races, and can only be re-used after all |
| /// active vector-clocks catch up with the threads timestamp. |
| reuse_candidates: RefCell<FxHashSet<VectorIdx>>, |
| |
| /// Counts the number of threads that are currently active |
| /// if the number of active threads reduces to 1 and then |
| /// a join operation occurs with the remaining main thread |
| /// then multi-threaded execution may be disabled. |
| active_thread_count: Cell<usize>, |
| |
| /// This contains threads that have terminated, but not yet joined |
| /// and so cannot become re-use candidates until a join operation |
| /// occurs. |
| /// The associated vector index will be moved into re-use candidates |
| /// after the join operation occurs. |
| terminated_threads: RefCell<FxHashMap<ThreadId, VectorIdx>>, |
| } |
| |
| impl GlobalState { |
| /// Create a new global state, setup with just thread-id=0 |
| /// advanced to timestamp = 1. |
| pub fn new() -> Self { |
| let global_state = GlobalState { |
| multi_threaded: Cell::new(false), |
| vector_clocks: RefCell::new(IndexVec::new()), |
| vector_info: RefCell::new(IndexVec::new()), |
| thread_info: RefCell::new(IndexVec::new()), |
| current_index: Cell::new(VectorIdx::new(0)), |
| active_thread_count: Cell::new(1), |
| reuse_candidates: RefCell::new(FxHashSet::default()), |
| terminated_threads: RefCell::new(FxHashMap::default()), |
| }; |
| |
| // Setup the main-thread since it is not explicitly created: |
| // uses vector index and thread-id 0, also the rust runtime gives |
| // the main-thread a name of "main". |
| let index = global_state.vector_clocks.borrow_mut().push(ThreadClockSet::default()); |
| global_state.vector_info.borrow_mut().push(ThreadId::new(0)); |
| global_state.thread_info.borrow_mut().push(ThreadExtraState { |
| vector_index: Some(index), |
| thread_name: Some("main".to_string().into_boxed_str()), |
| termination_vector_clock: None, |
| }); |
| |
| global_state |
| } |
| |
| // Try to find vector index values that can potentially be re-used |
| // by a new thread instead of a new vector index being created. |
| fn find_vector_index_reuse_candidate(&self) -> Option<VectorIdx> { |
| let mut reuse = self.reuse_candidates.borrow_mut(); |
| let vector_clocks = self.vector_clocks.borrow(); |
| let vector_info = self.vector_info.borrow(); |
| let terminated_threads = self.terminated_threads.borrow(); |
| for &candidate in reuse.iter() { |
| let target_timestamp = vector_clocks[candidate].clock[candidate]; |
| if vector_clocks.iter_enumerated().all(|(clock_idx, clock)| { |
| // The thread happens before the clock, and hence cannot report |
| // a data-race with this the candidate index. |
| let no_data_race = clock.clock[candidate] >= target_timestamp; |
| |
| // The vector represents a thread that has terminated and hence cannot |
| // report a data-race with the candidate index. |
| let thread_id = vector_info[clock_idx]; |
| let vector_terminated = |
| reuse.contains(&clock_idx) || terminated_threads.contains_key(&thread_id); |
| |
| // The vector index cannot report a race with the candidate index |
| // and hence allows the candidate index to be re-used. |
| no_data_race || vector_terminated |
| }) { |
| // All vector clocks for each vector index are equal to |
| // the target timestamp, and the thread is known to have |
| // terminated, therefore this vector clock index cannot |
| // report any more data-races. |
| assert!(reuse.remove(&candidate)); |
| return Some(candidate); |
| } |
| } |
| None |
| } |
| |
| // Hook for thread creation, enabled multi-threaded execution and marks |
| // the current thread timestamp as happening-before the current thread. |
| #[inline] |
| pub fn thread_created(&self, thread: ThreadId) { |
| let current_index = self.current_index(); |
| |
| // Increment the number of active threads. |
| let active_threads = self.active_thread_count.get(); |
| self.active_thread_count.set(active_threads + 1); |
| |
| // Enable multi-threaded execution, there are now two threads |
| // so data-races are now possible. |
| self.multi_threaded.set(true); |
| |
| // Load and setup the associated thread metadata |
| let mut thread_info = self.thread_info.borrow_mut(); |
| thread_info.ensure_contains_elem(thread, Default::default); |
| |
| // Assign a vector index for the thread, attempting to re-use an old |
| // vector index that can no longer report any data-races if possible. |
| let created_index = if let Some(reuse_index) = self.find_vector_index_reuse_candidate() { |
| // Now re-configure the re-use candidate, increment the clock |
| // for the new sync use of the vector. |
| let mut vector_clocks = self.vector_clocks.borrow_mut(); |
| vector_clocks[reuse_index].increment_clock(reuse_index); |
| |
| // Locate the old thread the vector was associated with and update |
| // it to represent the new thread instead. |
| let mut vector_info = self.vector_info.borrow_mut(); |
| let old_thread = vector_info[reuse_index]; |
| vector_info[reuse_index] = thread; |
| |
| // Mark the thread the vector index was associated with as no longer |
| // representing a thread index. |
| thread_info[old_thread].vector_index = None; |
| |
| reuse_index |
| } else { |
| // No vector re-use candidates available, instead create |
| // a new vector index. |
| let mut vector_info = self.vector_info.borrow_mut(); |
| vector_info.push(thread) |
| }; |
| |
| // Mark the chosen vector index as in use by the thread. |
| thread_info[thread].vector_index = Some(created_index); |
| |
| // Create a thread clock set if applicable. |
| let mut vector_clocks = self.vector_clocks.borrow_mut(); |
| if created_index == vector_clocks.next_index() { |
| vector_clocks.push(ThreadClockSet::default()); |
| } |
| |
| // Now load the two clocks and configure the initial state. |
| let (current, created) = vector_clocks.pick2_mut(current_index, created_index); |
| |
| // Join the created with current, since the current threads |
| // previous actions happen-before the created thread. |
| created.join_with(current); |
| |
| // Advance both threads after the synchronized operation. |
| // Both operations are considered to have release semantics. |
| current.increment_clock(current_index); |
| created.increment_clock(created_index); |
| } |
| |
| /// Hook on a thread join to update the implicit happens-before relation |
| /// between the joined thread and the current thread. |
| #[inline] |
| pub fn thread_joined(&self, current_thread: ThreadId, join_thread: ThreadId) { |
| let mut clocks_vec = self.vector_clocks.borrow_mut(); |
| let thread_info = self.thread_info.borrow(); |
| |
| // Load the vector clock of the current thread. |
| let current_index = thread_info[current_thread] |
| .vector_index |
| .expect("Performed thread join on thread with no assigned vector"); |
| let current = &mut clocks_vec[current_index]; |
| |
| // Load the associated vector clock for the terminated thread. |
| let join_clock = thread_info[join_thread] |
| .termination_vector_clock |
| .as_ref() |
| .expect("Joined with thread but thread has not terminated"); |
| |
| |
| // The join thread happens-before the current thread |
| // so update the current vector clock. |
| // Is not a release operation so the clock is not incremented. |
| current.clock.join(join_clock); |
| |
| // Check the number of active threads, if the value is 1 |
| // then test for potentially disabling multi-threaded execution. |
| let active_threads = self.active_thread_count.get(); |
| if active_threads == 1 { |
| // May potentially be able to disable multi-threaded execution. |
| let current_clock = &clocks_vec[current_index]; |
| if clocks_vec |
| .iter_enumerated() |
| .all(|(idx, clocks)| clocks.clock[idx] <= current_clock.clock[idx]) |
| { |
| // All thread terminations happen-before the current clock |
| // therefore no data-races can be reported until a new thread |
| // is created, so disable multi-threaded execution. |
| self.multi_threaded.set(false); |
| } |
| } |
| |
| // If the thread is marked as terminated but not joined |
| // then move the thread to the re-use set. |
| let mut termination = self.terminated_threads.borrow_mut(); |
| if let Some(index) = termination.remove(&join_thread) { |
| let mut reuse = self.reuse_candidates.borrow_mut(); |
| reuse.insert(index); |
| } |
| } |
| |
| /// On thread termination, the vector-clock may re-used |
| /// in the future once all remaining thread-clocks catch |
| /// up with the time index of the terminated thread. |
| /// This assigns thread termination with a unique index |
| /// which will be used to join the thread |
| /// This should be called strictly before any calls to |
| /// `thread_joined`. |
| #[inline] |
| pub fn thread_terminated(&self) { |
| let current_index = self.current_index(); |
| |
| // Increment the clock to a unique termination timestamp. |
| let mut vector_clocks = self.vector_clocks.borrow_mut(); |
| let current_clocks = &mut vector_clocks[current_index]; |
| current_clocks.increment_clock(current_index); |
| |
| // Load the current thread id for the executing vector. |
| let vector_info = self.vector_info.borrow(); |
| let current_thread = vector_info[current_index]; |
| |
| // Load the current thread metadata, and move to a terminated |
| // vector state. Setting up the vector clock all join operations |
| // will use. |
| let mut thread_info = self.thread_info.borrow_mut(); |
| let current = &mut thread_info[current_thread]; |
| current.termination_vector_clock = Some(current_clocks.clock.clone()); |
| |
| // Add this thread as a candidate for re-use after a thread join |
| // occurs. |
| let mut termination = self.terminated_threads.borrow_mut(); |
| termination.insert(current_thread, current_index); |
| |
| // Reduce the number of active threads, now that a thread has |
| // terminated. |
| let mut active_threads = self.active_thread_count.get(); |
| active_threads -= 1; |
| self.active_thread_count.set(active_threads); |
| } |
| |
| /// Hook for updating the local tracker of the currently |
| /// enabled thread, should always be updated whenever |
| /// `active_thread` in thread.rs is updated. |
| #[inline] |
| pub fn thread_set_active(&self, thread: ThreadId) { |
| let thread_info = self.thread_info.borrow(); |
| let vector_idx = thread_info[thread] |
| .vector_index |
| .expect("Setting thread active with no assigned vector"); |
| self.current_index.set(vector_idx); |
| } |
| |
| /// Hook for updating the local tracker of the threads name |
| /// this should always mirror the local value in thread.rs |
| /// the thread name is used for improved diagnostics |
| /// during a data-race. |
| #[inline] |
| pub fn thread_set_name(&self, thread: ThreadId, name: String) { |
| let name = name.into_boxed_str(); |
| let mut thread_info = self.thread_info.borrow_mut(); |
| thread_info[thread].thread_name = Some(name); |
| } |
| |
| /// Attempt to perform a synchronized operation, this |
| /// will perform no operation if multi-threading is |
| /// not currently enabled. |
| /// Otherwise it will increment the clock for the current |
| /// vector before and after the operation for data-race |
| /// detection between any happens-before edges the |
| /// operation may create. |
| fn maybe_perform_sync_operation<'tcx>( |
| &self, |
| op: impl FnOnce(VectorIdx, RefMut<'_, ThreadClockSet>) -> InterpResult<'tcx, bool>, |
| ) -> InterpResult<'tcx> { |
| if self.multi_threaded.get() { |
| let (index, clocks) = self.current_thread_state_mut(); |
| if op(index, clocks)? { |
| let (_, mut clocks) = self.current_thread_state_mut(); |
| clocks.increment_clock(index); |
| } |
| } |
| Ok(()) |
| } |
| |
| /// Internal utility to identify a thread stored internally |
| /// returns the id and the name for better diagnostics. |
| fn print_thread_metadata(&self, vector: VectorIdx) -> String { |
| let thread = self.vector_info.borrow()[vector]; |
| let thread_name = &self.thread_info.borrow()[thread].thread_name; |
| if let Some(name) = thread_name { |
| let name: &str = name; |
| format!("Thread(id = {:?}, name = {:?})", thread.to_u32(), &*name) |
| } else { |
| format!("Thread(id = {:?})", thread.to_u32()) |
| } |
| } |
| |
| /// Acquire a lock, express that the previous call of |
| /// `validate_lock_release` must happen before this. |
| /// As this is an acquire operation, the thread timestamp is not |
| /// incremented. |
| pub fn validate_lock_acquire(&self, lock: &VClock, thread: ThreadId) { |
| let (_, mut clocks) = self.load_thread_state_mut(thread); |
| clocks.clock.join(&lock); |
| } |
| |
| /// Release a lock handle, express that this happens-before |
| /// any subsequent calls to `validate_lock_acquire`. |
| /// For normal locks this should be equivalent to `validate_lock_release_shared` |
| /// since an acquire operation should have occurred before, however |
| /// for futex & condvar operations this is not the case and this |
| /// operation must be used. |
| pub fn validate_lock_release(&self, lock: &mut VClock, thread: ThreadId) { |
| let (index, mut clocks) = self.load_thread_state_mut(thread); |
| lock.clone_from(&clocks.clock); |
| clocks.increment_clock(index); |
| } |
| |
| /// Release a lock handle, express that this happens-before |
| /// any subsequent calls to `validate_lock_acquire` as well |
| /// as any previous calls to this function after any |
| /// `validate_lock_release` calls. |
| /// For normal locks this should be equivalent to `validate_lock_release`. |
| /// This function only exists for joining over the set of concurrent readers |
| /// in a read-write lock and should not be used for anything else. |
| pub fn validate_lock_release_shared(&self, lock: &mut VClock, thread: ThreadId) { |
| let (index, mut clocks) = self.load_thread_state_mut(thread); |
| lock.join(&clocks.clock); |
| clocks.increment_clock(index); |
| } |
| |
| /// Load the vector index used by the given thread as well as the set of vector clocks |
| /// used by the thread. |
| #[inline] |
| fn load_thread_state_mut(&self, thread: ThreadId) -> (VectorIdx, RefMut<'_, ThreadClockSet>) { |
| let index = self.thread_info.borrow()[thread] |
| .vector_index |
| .expect("Loading thread state for thread with no assigned vector"); |
| let ref_vector = self.vector_clocks.borrow_mut(); |
| let clocks = RefMut::map(ref_vector, |vec| &mut vec[index]); |
| (index, clocks) |
| } |
| |
| /// Load the current vector clock in use and the current set of thread clocks |
| /// in use for the vector. |
| #[inline] |
| fn current_thread_state(&self) -> (VectorIdx, Ref<'_, ThreadClockSet>) { |
| let index = self.current_index(); |
| let ref_vector = self.vector_clocks.borrow(); |
| let clocks = Ref::map(ref_vector, |vec| &vec[index]); |
| (index, clocks) |
| } |
| |
| /// Load the current vector clock in use and the current set of thread clocks |
| /// in use for the vector mutably for modification. |
| #[inline] |
| fn current_thread_state_mut(&self) -> (VectorIdx, RefMut<'_, ThreadClockSet>) { |
| let index = self.current_index(); |
| let ref_vector = self.vector_clocks.borrow_mut(); |
| let clocks = RefMut::map(ref_vector, |vec| &mut vec[index]); |
| (index, clocks) |
| } |
| |
| /// Return the current thread, should be the same |
| /// as the data-race active thread. |
| #[inline] |
| fn current_index(&self) -> VectorIdx { |
| self.current_index.get() |
| } |
| } |
