1 //! Global machine state as well as implementation of the interpreter engine
5 use std::cell::RefCell;
7 use std::num::NonZeroU64;
8 use std::time::Instant;
11 use rand::rngs::StdRng;
12 use rand::SeedableRng;
14 use rustc_data_structures::fx::FxHashMap;
19 layout::{LayoutCx, LayoutError, TyAndLayout},
23 use rustc_span::def_id::DefId;
24 use rustc_span::symbol::{sym, Symbol};
25 use rustc_target::abi::{LayoutOf, Size};
26 use rustc_target::spec::abi::Abi;
30 // Some global facts about the emulated machine.
31 pub const PAGE_SIZE: u64 = 4 * 1024; // FIXME: adjust to target architecture
32 pub const STACK_ADDR: u64 = 32 * PAGE_SIZE; // not really about the "stack", but where we start assigning integer addresses to allocations
33 pub const STACK_SIZE: u64 = 16 * PAGE_SIZE; // whatever
34 pub const NUM_CPUS: u64 = 1;
36 /// Extra data stored with each stack frame
38 pub struct FrameData<'tcx> {
39 /// Extra data for Stacked Borrows.
40 pub call_id: stacked_borrows::CallId,
42 /// If this is Some(), then this is a special "catch unwind" frame (the frame of `try_fn`
43 /// called by `try`). When this frame is popped during unwinding a panic,
44 /// we stop unwinding, use the `CatchUnwindData` to handle catching.
45 pub catch_unwind: Option<CatchUnwindData<'tcx>>,
48 /// Extra memory kinds
49 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
50 pub enum MiriMemoryKind {
51 /// `__rust_alloc` memory.
55 /// Windows `HeapAlloc` memory.
57 /// Memory for args, errno, and other parts of the machine-managed environment.
58 /// This memory may leak.
60 /// Memory for env vars. Separate from `Machine` because we clean it up and leak-check it.
62 /// Globals copied from `tcx`.
63 /// This memory may leak.
65 /// Memory for extern statics.
66 /// This memory may leak.
68 /// Memory for thread-local statics.
69 /// This memory may leak.
73 impl Into<MemoryKind<MiriMemoryKind>> for MiriMemoryKind {
75 fn into(self) -> MemoryKind<MiriMemoryKind> {
76 MemoryKind::Machine(self)
80 impl MayLeak for MiriMemoryKind {
82 fn may_leak(self) -> bool {
83 use self::MiriMemoryKind::*;
85 Rust | C | WinHeap | Env => false,
86 Machine | Global | ExternStatic | Tls => true,
91 impl fmt::Display for MiriMemoryKind {
92 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
93 use self::MiriMemoryKind::*;
95 Rust => write!(f, "Rust heap"),
96 C => write!(f, "C heap"),
97 WinHeap => write!(f, "Windows heap"),
98 Machine => write!(f, "machine-managed memory"),
99 Env => write!(f, "environment variable"),
100 Global => write!(f, "global (static or const)"),
101 ExternStatic => write!(f, "extern static"),
102 Tls => write!(f, "thread-local static"),
107 /// Extra per-allocation data
108 #[derive(Debug, Clone)]
109 pub struct AllocExtra {
110 /// Stacked Borrows state is only added if it is enabled.
111 pub stacked_borrows: Option<stacked_borrows::AllocExtra>,
112 /// Data race detection via the use of a vector-clock,
113 /// this is only added if it is enabled.
114 pub data_race: Option<data_race::AllocExtra>,
117 /// Extra global memory data
119 pub struct MemoryExtra {
120 pub stacked_borrows: Option<stacked_borrows::MemoryExtra>,
121 pub data_race: Option<data_race::MemoryExtra>,
122 pub intptrcast: intptrcast::MemoryExtra,
124 /// Mapping extern static names to their canonical allocation.
125 extern_statics: FxHashMap<Symbol, AllocId>,
127 /// The random number generator used for resolving non-determinism.
128 /// Needs to be queried by ptr_to_int, hence needs interior mutability.
129 pub(crate) rng: RefCell<StdRng>,
131 /// An allocation ID to report when it is being allocated
132 /// (helps for debugging memory leaks and use after free bugs).
133 tracked_alloc_id: Option<AllocId>,
135 /// Controls whether alignment of memory accesses is being checked.
136 pub(crate) check_alignment: AlignmentCheck,
138 /// Failure rate of compare_exchange_weak, between 0.0 and 1.0
139 pub(crate) cmpxchg_weak_failure_rate: f64,
143 pub fn new(config: &MiriConfig) -> Self {
144 let rng = StdRng::seed_from_u64(config.seed.unwrap_or(0));
145 let stacked_borrows = if config.stacked_borrows {
146 Some(RefCell::new(stacked_borrows::GlobalState::new(
147 config.tracked_pointer_tag,
148 config.tracked_call_id,
155 if config.data_race_detector { Some(data_race::GlobalState::new()) } else { None };
159 intptrcast: Default::default(),
160 extern_statics: FxHashMap::default(),
161 rng: RefCell::new(rng),
162 tracked_alloc_id: config.tracked_alloc_id,
163 check_alignment: config.check_alignment,
164 cmpxchg_weak_failure_rate: config.cmpxchg_weak_failure_rate,
168 fn add_extern_static<'tcx, 'mir>(
169 this: &mut MiriEvalContext<'mir, 'tcx>,
173 let ptr = ptr.assert_ptr();
174 assert_eq!(ptr.offset, Size::ZERO);
175 this.memory.extra.extern_statics.try_insert(Symbol::intern(name), ptr.alloc_id).unwrap();
178 /// Sets up the "extern statics" for this machine.
179 pub fn init_extern_statics<'tcx, 'mir>(
180 this: &mut MiriEvalContext<'mir, 'tcx>,
181 ) -> InterpResult<'tcx> {
182 match this.tcx.sess.target.os.as_str() {
184 // "__cxa_thread_atexit_impl"
185 // This should be all-zero, pointer-sized.
186 let layout = this.machine.layouts.usize;
187 let place = this.allocate(layout, MiriMemoryKind::ExternStatic.into());
188 this.write_scalar(Scalar::from_machine_usize(0, this), &place.into())?;
189 Self::add_extern_static(this, "__cxa_thread_atexit_impl", place.ptr);
191 Self::add_extern_static(
194 this.machine.env_vars.environ.unwrap().ptr,
199 // This is some obscure hack that is part of the Windows TLS story. It's a `u8`.
200 let layout = this.machine.layouts.u8;
201 let place = this.allocate(layout, MiriMemoryKind::ExternStatic.into());
202 this.write_scalar(Scalar::from_u8(0), &place.into())?;
203 Self::add_extern_static(this, "_tls_used", place.ptr);
205 _ => {} // No "extern statics" supported on this target
211 /// Precomputed layouts of primitive types
212 pub struct PrimitiveLayouts<'tcx> {
213 pub unit: TyAndLayout<'tcx>,
214 pub i8: TyAndLayout<'tcx>,
215 pub i32: TyAndLayout<'tcx>,
216 pub isize: TyAndLayout<'tcx>,
217 pub u8: TyAndLayout<'tcx>,
218 pub u32: TyAndLayout<'tcx>,
219 pub usize: TyAndLayout<'tcx>,
222 impl<'mir, 'tcx: 'mir> PrimitiveLayouts<'tcx> {
223 fn new(layout_cx: LayoutCx<'tcx, TyCtxt<'tcx>>) -> Result<Self, LayoutError<'tcx>> {
225 unit: layout_cx.layout_of(layout_cx.tcx.mk_unit())?,
226 i8: layout_cx.layout_of(layout_cx.tcx.types.i8)?,
227 i32: layout_cx.layout_of(layout_cx.tcx.types.i32)?,
228 isize: layout_cx.layout_of(layout_cx.tcx.types.isize)?,
229 u8: layout_cx.layout_of(layout_cx.tcx.types.u8)?,
230 u32: layout_cx.layout_of(layout_cx.tcx.types.u32)?,
231 usize: layout_cx.layout_of(layout_cx.tcx.types.usize)?,
236 /// The machine itself.
237 pub struct Evaluator<'mir, 'tcx> {
238 /// Environment variables set by `setenv`.
239 /// Miri does not expose env vars from the host to the emulated program.
240 pub(crate) env_vars: EnvVars<'tcx>,
242 /// Program arguments (`Option` because we can only initialize them after creating the ecx).
243 /// These are *pointers* to argc/argv because macOS.
244 /// We also need the full command line as one string because of Windows.
245 pub(crate) argc: Option<Scalar<Tag>>,
246 pub(crate) argv: Option<Scalar<Tag>>,
247 pub(crate) cmd_line: Option<Scalar<Tag>>,
250 pub(crate) tls: TlsData<'tcx>,
252 /// If enabled, the `env_vars` field is populated with the host env vars during initialization
253 /// and random number generation is delegated to the host.
254 pub(crate) communicate: bool,
256 /// Whether to enforce the validity invariant.
257 pub(crate) validate: bool,
259 pub(crate) file_handler: shims::posix::FileHandler,
260 pub(crate) dir_handler: shims::posix::DirHandler,
262 /// The "time anchor" for this machine's monotone clock (for `Instant` simulation).
263 pub(crate) time_anchor: Instant,
265 /// The set of threads.
266 pub(crate) threads: ThreadManager<'mir, 'tcx>,
268 /// Precomputed `TyLayout`s for primitive data types that are commonly used inside Miri.
269 pub(crate) layouts: PrimitiveLayouts<'tcx>,
271 /// Allocations that are considered roots of static memory (that may leak).
272 pub(crate) static_roots: Vec<AllocId>,
275 impl<'mir, 'tcx> Evaluator<'mir, 'tcx> {
279 layout_cx: LayoutCx<'tcx, TyCtxt<'tcx>>,
282 PrimitiveLayouts::new(layout_cx).expect("Couldn't get layouts of primitive types");
284 // `env_vars` could be initialized properly here if `Memory` were available before
285 // calling this method.
286 env_vars: EnvVars::default(),
290 tls: TlsData::default(),
293 file_handler: Default::default(),
294 dir_handler: Default::default(),
295 time_anchor: Instant::now(),
297 threads: ThreadManager::default(),
298 static_roots: Vec::new(),
303 /// A rustc InterpCx for Miri.
304 pub type MiriEvalContext<'mir, 'tcx> = InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>;
306 /// A little trait that's useful to be inherited by extension traits.
307 pub trait MiriEvalContextExt<'mir, 'tcx> {
308 fn eval_context_ref<'a>(&'a self) -> &'a MiriEvalContext<'mir, 'tcx>;
309 fn eval_context_mut<'a>(&'a mut self) -> &'a mut MiriEvalContext<'mir, 'tcx>;
311 impl<'mir, 'tcx> MiriEvalContextExt<'mir, 'tcx> for MiriEvalContext<'mir, 'tcx> {
313 fn eval_context_ref(&self) -> &MiriEvalContext<'mir, 'tcx> {
317 fn eval_context_mut(&mut self) -> &mut MiriEvalContext<'mir, 'tcx> {
322 /// Machine hook implementations.
323 impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'mir, 'tcx> {
324 type MemoryKind = MiriMemoryKind;
326 type FrameExtra = FrameData<'tcx>;
327 type MemoryExtra = MemoryExtra;
328 type AllocExtra = AllocExtra;
329 type PointerTag = Tag;
330 type ExtraFnVal = Dlsym;
333 MonoHashMap<AllocId, (MemoryKind<MiriMemoryKind>, Allocation<Tag, Self::AllocExtra>)>;
335 const GLOBAL_KIND: Option<MiriMemoryKind> = Some(MiriMemoryKind::Global);
338 fn enforce_alignment(memory_extra: &MemoryExtra) -> bool {
339 memory_extra.check_alignment != AlignmentCheck::None
343 fn force_int_for_alignment_check(memory_extra: &Self::MemoryExtra) -> bool {
344 memory_extra.check_alignment == AlignmentCheck::Int
348 fn enforce_validity(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool {
353 fn find_mir_or_eval_fn(
354 ecx: &mut InterpCx<'mir, 'tcx, Self>,
355 instance: ty::Instance<'tcx>,
357 args: &[OpTy<'tcx, Tag>],
358 ret: Option<(&PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
359 unwind: Option<mir::BasicBlock>,
360 ) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
361 ecx.find_mir_or_eval_fn(instance, abi, args, ret, unwind)
366 ecx: &mut InterpCx<'mir, 'tcx, Self>,
369 args: &[OpTy<'tcx, Tag>],
370 ret: Option<(&PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
371 _unwind: Option<mir::BasicBlock>,
372 ) -> InterpResult<'tcx> {
373 ecx.call_dlsym(fn_val, abi, args, ret)
378 ecx: &mut rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
379 instance: ty::Instance<'tcx>,
380 args: &[OpTy<'tcx, Tag>],
381 ret: Option<(&PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
382 unwind: Option<mir::BasicBlock>,
383 ) -> InterpResult<'tcx> {
384 ecx.call_intrinsic(instance, args, ret, unwind)
389 ecx: &mut InterpCx<'mir, 'tcx, Self>,
390 msg: &mir::AssertMessage<'tcx>,
391 unwind: Option<mir::BasicBlock>,
392 ) -> InterpResult<'tcx> {
393 ecx.assert_panic(msg, unwind)
397 fn abort(_ecx: &mut InterpCx<'mir, 'tcx, Self>, msg: String) -> InterpResult<'tcx, !> {
398 throw_machine_stop!(TerminationInfo::Abort(msg))
403 ecx: &rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
405 left: &ImmTy<'tcx, Tag>,
406 right: &ImmTy<'tcx, Tag>,
407 ) -> InterpResult<'tcx, (Scalar<Tag>, bool, ty::Ty<'tcx>)> {
408 ecx.binary_ptr_op(bin_op, left, right)
412 ecx: &mut InterpCx<'mir, 'tcx, Self>,
413 dest: &PlaceTy<'tcx, Tag>,
414 ) -> InterpResult<'tcx> {
415 trace!("box_alloc for {:?}", dest.layout.ty);
416 let layout = ecx.layout_of(dest.layout.ty.builtin_deref(false).unwrap().ty)?;
417 // First argument: `size`.
418 // (`0` is allowed here -- this is expected to be handled by the lang item).
419 let size = Scalar::from_machine_usize(layout.size.bytes(), ecx);
421 // Second argument: `align`.
422 let align = Scalar::from_machine_usize(layout.align.abi.bytes(), ecx);
424 // Call the `exchange_malloc` lang item.
425 let malloc = ecx.tcx.lang_items().exchange_malloc_fn().unwrap();
426 let malloc = ty::Instance::mono(ecx.tcx.tcx, malloc);
430 &[size.into(), align.into()],
432 // Don't do anything when we are done. The `statement()` function will increment
433 // the old stack frame's stmt counter to the next statement, which means that when
434 // `exchange_malloc` returns, we go on evaluating exactly where we want to be.
435 StackPopCleanup::None { cleanup: true },
440 fn thread_local_static_alloc_id(
441 ecx: &mut InterpCx<'mir, 'tcx, Self>,
443 ) -> InterpResult<'tcx, AllocId> {
444 ecx.get_or_create_thread_local_alloc_id(def_id)
447 fn extern_static_alloc_id(
448 memory: &Memory<'mir, 'tcx, Self>,
450 ) -> InterpResult<'tcx, AllocId> {
451 let attrs = memory.tcx.get_attrs(def_id);
452 let link_name = match memory.tcx.sess.first_attr_value_str_by_name(&attrs, sym::link_name) {
454 None => memory.tcx.item_name(def_id),
456 if let Some(&id) = memory.extra.extern_statics.get(&link_name) {
459 throw_unsup_format!("`extern` static {:?} is not supported by Miri", def_id)
463 fn init_allocation_extra<'b>(
464 memory_extra: &MemoryExtra,
466 alloc: Cow<'b, Allocation>,
467 kind: Option<MemoryKind<Self::MemoryKind>>,
468 ) -> (Cow<'b, Allocation<Self::PointerTag, Self::AllocExtra>>, Self::PointerTag) {
469 if Some(id) == memory_extra.tracked_alloc_id {
470 register_diagnostic(NonHaltingDiagnostic::CreatedAlloc(id));
473 let kind = kind.expect("we set our STATIC_KIND so this cannot be None");
474 let alloc = alloc.into_owned();
475 let (stacks, base_tag) = if let Some(stacked_borrows) = &memory_extra.stacked_borrows {
476 let (stacks, base_tag) =
477 Stacks::new_allocation(id, alloc.size(), stacked_borrows, kind);
478 (Some(stacks), base_tag)
480 // No stacks, no tag.
481 (None, Tag::Untagged)
483 let race_alloc = if let Some(data_race) = &memory_extra.data_race {
484 Some(data_race::AllocExtra::new_allocation(&data_race, alloc.size(), kind))
488 let mut stacked_borrows = memory_extra.stacked_borrows.as_ref().map(|sb| sb.borrow_mut());
489 let alloc: Allocation<Tag, Self::AllocExtra> = alloc.with_tags_and_extra(
491 if let Some(stacked_borrows) = &mut stacked_borrows {
492 // Only globals may already contain pointers at this point
493 assert_eq!(kind, MiriMemoryKind::Global.into());
494 stacked_borrows.global_base_ptr(alloc)
499 AllocExtra { stacked_borrows: stacks, data_race: race_alloc },
501 (Cow::Owned(alloc), base_tag)
506 memory_extra: &Self::MemoryExtra,
507 alloc_extra: &AllocExtra,
510 ) -> InterpResult<'tcx> {
511 if let Some(data_race) = &alloc_extra.data_race {
512 data_race.read(ptr, size, memory_extra.data_race.as_ref().unwrap())?;
514 if let Some(stacked_borrows) = &alloc_extra.stacked_borrows {
515 stacked_borrows.memory_read(ptr, size, memory_extra.stacked_borrows.as_ref().unwrap())
523 memory_extra: &mut Self::MemoryExtra,
524 alloc_extra: &mut AllocExtra,
527 ) -> InterpResult<'tcx> {
528 if let Some(data_race) = &mut alloc_extra.data_race {
529 data_race.write(ptr, size, memory_extra.data_race.as_mut().unwrap())?;
531 if let Some(stacked_borrows) = &mut alloc_extra.stacked_borrows {
532 stacked_borrows.memory_written(
535 memory_extra.stacked_borrows.as_mut().unwrap(),
543 fn memory_deallocated(
544 memory_extra: &mut Self::MemoryExtra,
545 alloc_extra: &mut AllocExtra,
548 ) -> InterpResult<'tcx> {
549 if Some(ptr.alloc_id) == memory_extra.tracked_alloc_id {
550 register_diagnostic(NonHaltingDiagnostic::FreedAlloc(ptr.alloc_id));
552 if let Some(data_race) = &mut alloc_extra.data_race {
553 data_race.deallocate(ptr, size, memory_extra.data_race.as_mut().unwrap())?;
555 if let Some(stacked_borrows) = &mut alloc_extra.stacked_borrows {
556 stacked_borrows.memory_deallocated(
559 memory_extra.stacked_borrows.as_mut().unwrap(),
566 fn after_static_mem_initialized(
567 ecx: &mut InterpCx<'mir, 'tcx, Self>,
568 ptr: Pointer<Self::PointerTag>,
570 ) -> InterpResult<'tcx> {
571 if ecx.memory.extra.data_race.is_some() {
572 ecx.reset_vector_clocks(ptr, size)?;
578 fn tag_global_base_pointer(memory_extra: &MemoryExtra, id: AllocId) -> Self::PointerTag {
579 if let Some(stacked_borrows) = &memory_extra.stacked_borrows {
580 stacked_borrows.borrow_mut().global_base_ptr(id)
588 ecx: &mut InterpCx<'mir, 'tcx, Self>,
589 kind: mir::RetagKind,
590 place: &PlaceTy<'tcx, Tag>,
591 ) -> InterpResult<'tcx> {
592 if ecx.memory.extra.stacked_borrows.is_some() { ecx.retag(kind, place) } else { Ok(()) }
597 ecx: &mut InterpCx<'mir, 'tcx, Self>,
598 frame: Frame<'mir, 'tcx, Tag>,
599 ) -> InterpResult<'tcx, Frame<'mir, 'tcx, Tag, FrameData<'tcx>>> {
600 let stacked_borrows = ecx.memory.extra.stacked_borrows.as_ref();
601 let call_id = stacked_borrows.map_or(NonZeroU64::new(1).unwrap(), |stacked_borrows| {
602 stacked_borrows.borrow_mut().new_call()
604 let extra = FrameData { call_id, catch_unwind: None };
605 Ok(frame.with_extra(extra))
609 ecx: &'a InterpCx<'mir, 'tcx, Self>,
610 ) -> &'a [Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>] {
611 ecx.active_thread_stack()
615 ecx: &'a mut InterpCx<'mir, 'tcx, Self>,
616 ) -> &'a mut Vec<Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>> {
617 ecx.active_thread_stack_mut()
621 fn after_stack_push(ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx> {
622 if ecx.memory.extra.stacked_borrows.is_some() { ecx.retag_return_place() } else { Ok(()) }
627 ecx: &mut InterpCx<'mir, 'tcx, Self>,
628 frame: Frame<'mir, 'tcx, Tag, FrameData<'tcx>>,
630 ) -> InterpResult<'tcx, StackPopJump> {
631 ecx.handle_stack_pop(frame.extra, unwinding)
636 memory: &Memory<'mir, 'tcx, Self>,
638 ) -> InterpResult<'tcx, Pointer<Self::PointerTag>> {
639 intptrcast::GlobalState::int_to_ptr(int, memory)
644 memory: &Memory<'mir, 'tcx, Self>,
645 ptr: Pointer<Self::PointerTag>,
646 ) -> InterpResult<'tcx, u64> {
647 intptrcast::GlobalState::ptr_to_int(ptr, memory)