1 //! Global machine state as well as implementation of the interpreter engine
5 use std::cell::RefCell;
6 use std::num::NonZeroU64;
8 use std::time::Instant;
12 use rand::rngs::StdRng;
15 use rustc_data_structures::fx::FxHashMap;
20 layout::{LayoutCx, LayoutError, TyAndLayout},
24 use rustc_span::symbol::{sym, Symbol};
25 use rustc_span::def_id::DefId;
26 use rustc_target::abi::{LayoutOf, Size};
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, extern statics 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.
67 impl Into<MemoryKind<MiriMemoryKind>> for MiriMemoryKind {
69 fn into(self) -> MemoryKind<MiriMemoryKind> {
70 MemoryKind::Machine(self)
74 impl MayLeak for MiriMemoryKind {
76 fn may_leak(self) -> bool {
77 use self::MiriMemoryKind::*;
79 Rust | C | WinHeap | Env => false,
80 Machine | Global => true,
85 impl fmt::Display for MiriMemoryKind {
86 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
87 use self::MiriMemoryKind::*;
89 Rust => write!(f, "Rust heap"),
90 C => write!(f, "C heap"),
91 WinHeap => write!(f, "Windows heap"),
92 Machine => write!(f, "machine-managed memory"),
93 Env => write!(f, "environment variable"),
94 Global => write!(f, "global"),
99 /// Extra per-allocation data
100 #[derive(Debug, Clone)]
101 pub struct AllocExtra {
102 /// Stacked Borrows state is only added if it is enabled.
103 pub stacked_borrows: Option<stacked_borrows::AllocExtra>,
106 /// Extra global memory data
107 #[derive(Clone, Debug)]
108 pub struct MemoryExtra {
109 pub stacked_borrows: Option<stacked_borrows::MemoryExtra>,
110 pub intptrcast: intptrcast::MemoryExtra,
112 /// Mapping extern static names to their canonical allocation.
113 extern_statics: FxHashMap<Symbol, AllocId>,
115 /// The random number generator used for resolving non-determinism.
116 /// Needs to be queried by ptr_to_int, hence needs interior mutability.
117 pub(crate) rng: RefCell<StdRng>,
119 /// An allocation ID to report when it is being allocated
120 /// (helps for debugging memory leaks and use after free bugs).
121 tracked_alloc_id: Option<AllocId>,
123 /// Controls whether alignment of memory accesses is being checked.
124 check_alignment: bool,
130 stacked_borrows: bool,
131 tracked_pointer_tag: Option<PtrId>,
132 tracked_call_id: Option<CallId>,
133 tracked_alloc_id: Option<AllocId>,
134 check_alignment: bool,
136 let stacked_borrows = if stacked_borrows {
137 Some(Rc::new(RefCell::new(stacked_borrows::GlobalState::new(tracked_pointer_tag, tracked_call_id))))
143 intptrcast: Default::default(),
144 extern_statics: FxHashMap::default(),
145 rng: RefCell::new(rng),
151 fn add_extern_static<'tcx, 'mir>(
152 this: &mut MiriEvalContext<'mir, 'tcx>,
156 let ptr = ptr.assert_ptr();
157 assert_eq!(ptr.offset, Size::ZERO);
161 .insert(Symbol::intern(name), ptr.alloc_id)
165 /// Sets up the "extern statics" for this machine.
166 pub fn init_extern_statics<'tcx, 'mir>(
167 this: &mut MiriEvalContext<'mir, 'tcx>,
168 ) -> InterpResult<'tcx> {
169 match this.tcx.sess.target.target.target_os.as_str() {
171 // "__cxa_thread_atexit_impl"
172 // This should be all-zero, pointer-sized.
173 let layout = this.machine.layouts.usize;
174 let place = this.allocate(layout, MiriMemoryKind::Machine.into());
175 this.write_scalar(Scalar::from_machine_usize(0, this), place.into())?;
176 Self::add_extern_static(this, "__cxa_thread_atexit_impl", place.ptr);
178 Self::add_extern_static(this, "environ", this.machine.env_vars.environ.unwrap().ptr);
182 // This is some obscure hack that is part of the Windows TLS story. It's a `u8`.
183 let layout = this.machine.layouts.u8;
184 let place = this.allocate(layout, MiriMemoryKind::Machine.into());
185 this.write_scalar(Scalar::from_u8(0), place.into())?;
186 Self::add_extern_static(this, "_tls_used", place.ptr);
188 _ => {} // No "extern statics" supported on this target
194 /// Precomputed layouts of primitive types
195 pub struct PrimitiveLayouts<'tcx> {
196 pub unit: TyAndLayout<'tcx>,
197 pub i8: TyAndLayout<'tcx>,
198 pub i32: TyAndLayout<'tcx>,
199 pub isize: TyAndLayout<'tcx>,
200 pub u8: TyAndLayout<'tcx>,
201 pub u32: TyAndLayout<'tcx>,
202 pub usize: TyAndLayout<'tcx>,
205 impl<'mir, 'tcx: 'mir> PrimitiveLayouts<'tcx> {
206 fn new(layout_cx: LayoutCx<'tcx, TyCtxt<'tcx>>) -> Result<Self, LayoutError<'tcx>> {
208 unit: layout_cx.layout_of(layout_cx.tcx.mk_unit())?,
209 i8: layout_cx.layout_of(layout_cx.tcx.types.i8)?,
210 i32: layout_cx.layout_of(layout_cx.tcx.types.i32)?,
211 isize: layout_cx.layout_of(layout_cx.tcx.types.isize)?,
212 u8: layout_cx.layout_of(layout_cx.tcx.types.u8)?,
213 u32: layout_cx.layout_of(layout_cx.tcx.types.u32)?,
214 usize: layout_cx.layout_of(layout_cx.tcx.types.usize)?,
219 /// The machine itself.
220 pub struct Evaluator<'mir, 'tcx> {
221 /// Environment variables set by `setenv`.
222 /// Miri does not expose env vars from the host to the emulated program.
223 pub(crate) env_vars: EnvVars<'tcx>,
225 /// Program arguments (`Option` because we can only initialize them after creating the ecx).
226 /// These are *pointers* to argc/argv because macOS.
227 /// We also need the full command line as one string because of Windows.
228 pub(crate) argc: Option<Scalar<Tag>>,
229 pub(crate) argv: Option<Scalar<Tag>>,
230 pub(crate) cmd_line: Option<Scalar<Tag>>,
232 /// Last OS error location in memory. It is a 32-bit integer.
233 pub(crate) last_error: Option<MPlaceTy<'tcx, Tag>>,
236 pub(crate) tls: TlsData<'tcx>,
238 /// If enabled, the `env_vars` field is populated with the host env vars during initialization
239 /// and random number generation is delegated to the host.
240 pub(crate) communicate: bool,
242 /// Whether to enforce the validity invariant.
243 pub(crate) validate: bool,
245 pub(crate) file_handler: shims::posix::FileHandler,
246 pub(crate) dir_handler: shims::posix::DirHandler,
248 /// The temporary used for storing the argument of
249 /// the call to `miri_start_panic` (the panic payload) when unwinding.
250 /// This is pointer-sized, and matches the `Payload` type in `src/libpanic_unwind/miri.rs`.
251 pub(crate) panic_payload: Option<Scalar<Tag>>,
253 /// The "time anchor" for this machine's monotone clock (for `Instant` simulation).
254 pub(crate) time_anchor: Instant,
256 /// The set of threads.
257 pub(crate) threads: ThreadManager<'mir, 'tcx>,
259 /// Precomputed `TyLayout`s for primitive data types that are commonly used inside Miri.
260 pub(crate) layouts: PrimitiveLayouts<'tcx>,
263 impl<'mir, 'tcx> Evaluator<'mir, 'tcx> {
267 layout_cx: LayoutCx<'tcx, TyCtxt<'tcx>>,
269 let layouts = PrimitiveLayouts::new(layout_cx)
270 .expect("Couldn't get layouts of primitive types");
272 // `env_vars` could be initialized properly here if `Memory` were available before
273 // calling this method.
274 env_vars: EnvVars::default(),
279 tls: TlsData::default(),
282 file_handler: Default::default(),
283 dir_handler: Default::default(),
285 time_anchor: Instant::now(),
287 threads: ThreadManager::default(),
292 /// A rustc InterpCx for Miri.
293 pub type MiriEvalContext<'mir, 'tcx> = InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>;
295 /// A little trait that's useful to be inherited by extension traits.
296 pub trait MiriEvalContextExt<'mir, 'tcx> {
297 fn eval_context_ref<'a>(&'a self) -> &'a MiriEvalContext<'mir, 'tcx>;
298 fn eval_context_mut<'a>(&'a mut self) -> &'a mut MiriEvalContext<'mir, 'tcx>;
300 impl<'mir, 'tcx> MiriEvalContextExt<'mir, 'tcx> for MiriEvalContext<'mir, 'tcx> {
302 fn eval_context_ref(&self) -> &MiriEvalContext<'mir, 'tcx> {
306 fn eval_context_mut(&mut self) -> &mut MiriEvalContext<'mir, 'tcx> {
311 /// Machine hook implementations.
312 impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'mir, 'tcx> {
313 type MemoryKind = MiriMemoryKind;
315 type FrameExtra = FrameData<'tcx>;
316 type MemoryExtra = MemoryExtra;
317 type AllocExtra = AllocExtra;
318 type PointerTag = Tag;
319 type ExtraFnVal = Dlsym;
322 MonoHashMap<AllocId, (MemoryKind<MiriMemoryKind>, Allocation<Tag, Self::AllocExtra>)>;
324 const GLOBAL_KIND: Option<MiriMemoryKind> = Some(MiriMemoryKind::Global);
327 fn enforce_alignment(memory_extra: &MemoryExtra) -> bool {
328 memory_extra.check_alignment
332 fn enforce_validity(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool {
337 fn find_mir_or_eval_fn(
338 ecx: &mut InterpCx<'mir, 'tcx, Self>,
339 instance: ty::Instance<'tcx>,
340 args: &[OpTy<'tcx, Tag>],
341 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
342 unwind: Option<mir::BasicBlock>,
343 ) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
344 ecx.find_mir_or_eval_fn(instance, args, ret, unwind)
349 ecx: &mut InterpCx<'mir, 'tcx, Self>,
351 args: &[OpTy<'tcx, Tag>],
352 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
353 _unwind: Option<mir::BasicBlock>,
354 ) -> InterpResult<'tcx> {
355 ecx.call_dlsym(fn_val, args, ret)
360 ecx: &mut rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
361 instance: ty::Instance<'tcx>,
362 args: &[OpTy<'tcx, Tag>],
363 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
364 unwind: Option<mir::BasicBlock>,
365 ) -> InterpResult<'tcx> {
366 ecx.call_intrinsic(instance, args, ret, unwind)
371 ecx: &mut InterpCx<'mir, 'tcx, Self>,
372 msg: &mir::AssertMessage<'tcx>,
373 unwind: Option<mir::BasicBlock>,
374 ) -> InterpResult<'tcx> {
375 ecx.assert_panic(msg, unwind)
379 fn abort(_ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx, !> {
380 throw_machine_stop!(TerminationInfo::Abort(None))
385 ecx: &rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
387 left: ImmTy<'tcx, Tag>,
388 right: ImmTy<'tcx, Tag>,
389 ) -> InterpResult<'tcx, (Scalar<Tag>, bool, ty::Ty<'tcx>)> {
390 ecx.binary_ptr_op(bin_op, left, right)
394 ecx: &mut InterpCx<'mir, 'tcx, Self>,
395 dest: PlaceTy<'tcx, Tag>,
396 ) -> InterpResult<'tcx> {
397 trace!("box_alloc for {:?}", dest.layout.ty);
398 let layout = ecx.layout_of(dest.layout.ty.builtin_deref(false).unwrap().ty)?;
399 // First argument: `size`.
400 // (`0` is allowed here -- this is expected to be handled by the lang item).
401 let size = Scalar::from_machine_usize(layout.size.bytes(), ecx);
403 // Second argument: `align`.
404 let align = Scalar::from_machine_usize(layout.align.abi.bytes(), ecx);
406 // Call the `exchange_malloc` lang item.
407 let malloc = ecx.tcx.lang_items().exchange_malloc_fn().unwrap();
408 let malloc = ty::Instance::mono(ecx.tcx.tcx, malloc);
411 &[size.into(), align.into()],
413 // Don't do anything when we are done. The `statement()` function will increment
414 // the old stack frame's stmt counter to the next statement, which means that when
415 // `exchange_malloc` returns, we go on evaluating exactly where we want to be.
416 StackPopCleanup::None { cleanup: true },
421 fn thread_local_alloc_id(
422 ecx: &mut InterpCx<'mir, 'tcx, Self>,
424 ) -> InterpResult<'tcx, AllocId> {
425 ecx.get_or_create_thread_local_alloc_id(def_id)
428 fn adjust_global_const(
429 ecx: &InterpCx<'mir, 'tcx, Self>,
430 mut val: mir::interpret::ConstValue<'tcx>,
431 ) -> InterpResult<'tcx, mir::interpret::ConstValue<'tcx>> {
432 // FIXME: Remove this, do The Right Thing in `thread_local_alloc_id` instead.
433 ecx.remap_thread_local_alloc_ids(&mut val)?;
437 fn canonical_alloc_id(mem: &Memory<'mir, 'tcx, Self>, id: AllocId) -> AllocId {
439 // Figure out if this is an extern static, and if yes, which one.
440 let def_id = match tcx.get_global_alloc(id) {
441 Some(GlobalAlloc::Static(def_id)) if tcx.is_foreign_item(def_id) => def_id,
443 // No need to canonicalize anything.
447 let attrs = tcx.get_attrs(def_id);
448 let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
450 None => tcx.item_name(def_id),
452 // Check if we know this one.
453 if let Some(canonical_id) = mem.extra.extern_statics.get(&link_name) {
454 trace!("canonical_alloc_id: {:?} ({}) -> {:?}", id, link_name, canonical_id);
457 // Return original id; `Memory::get_static_alloc` will throw an error.
462 fn init_allocation_extra<'b>(
463 memory_extra: &MemoryExtra,
465 alloc: Cow<'b, Allocation>,
466 kind: Option<MemoryKind<Self::MemoryKind>>,
467 ) -> (Cow<'b, Allocation<Self::PointerTag, Self::AllocExtra>>, Self::PointerTag) {
468 if Some(id) == memory_extra.tracked_alloc_id {
469 register_diagnostic(NonHaltingDiagnostic::CreatedAlloc(id));
472 let kind = kind.expect("we set our STATIC_KIND so this cannot be None");
473 let alloc = alloc.into_owned();
474 let (stacks, base_tag) =
475 if let Some(stacked_borrows) = &memory_extra.stacked_borrows {
476 let (stacks, base_tag) =
477 Stacks::new_allocation(id, alloc.size, Rc::clone(stacked_borrows), kind);
478 (Some(stacks), base_tag)
480 // No stacks, no tag.
481 (None, Tag::Untagged)
483 let mut stacked_borrows = memory_extra.stacked_borrows.as_ref().map(|sb| sb.borrow_mut());
484 let alloc: Allocation<Tag, Self::AllocExtra> = alloc.with_tags_and_extra(
486 if let Some(stacked_borrows) = &mut stacked_borrows {
487 // Only globals may already contain pointers at this point
488 assert_eq!(kind, MiriMemoryKind::Global.into());
489 stacked_borrows.global_base_ptr(alloc)
494 AllocExtra { stacked_borrows: stacks },
496 (Cow::Owned(alloc), base_tag)
500 fn before_deallocation(
501 memory_extra: &mut Self::MemoryExtra,
503 ) -> InterpResult<'tcx> {
504 if Some(id) == memory_extra.tracked_alloc_id {
505 register_diagnostic(NonHaltingDiagnostic::FreedAlloc(id));
512 fn tag_global_base_pointer(memory_extra: &MemoryExtra, id: AllocId) -> Self::PointerTag {
513 if let Some(stacked_borrows) = &memory_extra.stacked_borrows {
514 stacked_borrows.borrow_mut().global_base_ptr(id)
522 ecx: &mut InterpCx<'mir, 'tcx, Self>,
523 kind: mir::RetagKind,
524 place: PlaceTy<'tcx, Tag>,
525 ) -> InterpResult<'tcx> {
526 if ecx.memory.extra.stacked_borrows.is_some() {
527 ecx.retag(kind, place)
535 ecx: &mut InterpCx<'mir, 'tcx, Self>,
536 frame: Frame<'mir, 'tcx, Tag>,
537 ) -> InterpResult<'tcx, Frame<'mir, 'tcx, Tag, FrameData<'tcx>>> {
538 let stacked_borrows = ecx.memory.extra.stacked_borrows.as_ref();
539 let call_id = stacked_borrows.map_or(NonZeroU64::new(1).unwrap(), |stacked_borrows| {
540 stacked_borrows.borrow_mut().new_call()
542 let extra = FrameData { call_id, catch_unwind: None };
543 Ok(frame.with_extra(extra))
547 ecx: &'a InterpCx<'mir, 'tcx, Self>
548 ) -> &'a [Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>] {
549 ecx.active_thread_stack()
553 ecx: &'a mut InterpCx<'mir, 'tcx, Self>
554 ) -> &'a mut Vec<Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>> {
555 ecx.active_thread_stack_mut()
559 fn after_stack_push(ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx> {
560 if ecx.memory.extra.stacked_borrows.is_some() {
561 ecx.retag_return_place()
569 ecx: &mut InterpCx<'mir, 'tcx, Self>,
570 frame: Frame<'mir, 'tcx, Tag, FrameData<'tcx>>,
572 ) -> InterpResult<'tcx, StackPopJump> {
573 ecx.handle_stack_pop(frame.extra, unwinding)
578 memory: &Memory<'mir, 'tcx, Self>,
580 ) -> InterpResult<'tcx, Pointer<Self::PointerTag>> {
581 intptrcast::GlobalState::int_to_ptr(int, memory)
586 memory: &Memory<'mir, 'tcx, Self>,
587 ptr: Pointer<Self::PointerTag>,
588 ) -> InterpResult<'tcx, u64> {
589 intptrcast::GlobalState::ptr_to_int(ptr, memory)
593 impl AllocationExtra<Tag> for AllocExtra {
595 fn memory_read<'tcx>(
596 alloc: &Allocation<Tag, AllocExtra>,
599 ) -> InterpResult<'tcx> {
600 if let Some(stacked_borrows) = &alloc.extra.stacked_borrows {
601 stacked_borrows.memory_read(ptr, size)
608 fn memory_written<'tcx>(
609 alloc: &mut Allocation<Tag, AllocExtra>,
612 ) -> InterpResult<'tcx> {
613 if let Some(stacked_borrows) = &mut alloc.extra.stacked_borrows {
614 stacked_borrows.memory_written(ptr, size)
621 fn memory_deallocated<'tcx>(
622 alloc: &mut Allocation<Tag, AllocExtra>,
625 ) -> InterpResult<'tcx> {
626 if let Some(stacked_borrows) = &mut alloc.extra.stacked_borrows {
627 stacked_borrows.memory_deallocated(ptr, size)