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, 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>,
114 /// Extra global memory data
115 #[derive(Clone, Debug)]
116 pub struct MemoryExtra {
117 pub stacked_borrows: Option<stacked_borrows::MemoryExtra>,
118 pub intptrcast: intptrcast::MemoryExtra,
120 /// Mapping extern static names to their canonical allocation.
121 extern_statics: FxHashMap<Symbol, AllocId>,
123 /// The random number generator used for resolving non-determinism.
124 /// Needs to be queried by ptr_to_int, hence needs interior mutability.
125 pub(crate) rng: RefCell<StdRng>,
127 /// An allocation ID to report when it is being allocated
128 /// (helps for debugging memory leaks and use after free bugs).
129 tracked_alloc_id: Option<AllocId>,
131 /// Controls whether alignment of memory accesses is being checked.
132 check_alignment: bool,
138 stacked_borrows: bool,
139 tracked_pointer_tag: Option<PtrId>,
140 tracked_call_id: Option<CallId>,
141 tracked_alloc_id: Option<AllocId>,
142 check_alignment: bool,
144 let stacked_borrows = if stacked_borrows {
145 Some(Rc::new(RefCell::new(stacked_borrows::GlobalState::new(tracked_pointer_tag, tracked_call_id))))
151 intptrcast: Default::default(),
152 extern_statics: FxHashMap::default(),
153 rng: RefCell::new(rng),
159 fn add_extern_static<'tcx, 'mir>(
160 this: &mut MiriEvalContext<'mir, 'tcx>,
164 let ptr = ptr.assert_ptr();
165 assert_eq!(ptr.offset, Size::ZERO);
169 .insert(Symbol::intern(name), ptr.alloc_id)
173 /// Sets up the "extern statics" for this machine.
174 pub fn init_extern_statics<'tcx, 'mir>(
175 this: &mut MiriEvalContext<'mir, 'tcx>,
176 ) -> InterpResult<'tcx> {
177 match this.tcx.sess.target.target.target_os.as_str() {
179 // "__cxa_thread_atexit_impl"
180 // This should be all-zero, pointer-sized.
181 let layout = this.machine.layouts.usize;
182 let place = this.allocate(layout, MiriMemoryKind::ExternStatic.into());
183 this.write_scalar(Scalar::from_machine_usize(0, this), place.into())?;
184 Self::add_extern_static(this, "__cxa_thread_atexit_impl", place.ptr);
186 Self::add_extern_static(this, "environ", this.machine.env_vars.environ.unwrap().ptr);
190 // This is some obscure hack that is part of the Windows TLS story. It's a `u8`.
191 let layout = this.machine.layouts.u8;
192 let place = this.allocate(layout, MiriMemoryKind::ExternStatic.into());
193 this.write_scalar(Scalar::from_u8(0), place.into())?;
194 Self::add_extern_static(this, "_tls_used", place.ptr);
196 _ => {} // No "extern statics" supported on this target
202 /// Precomputed layouts of primitive types
203 pub struct PrimitiveLayouts<'tcx> {
204 pub unit: TyAndLayout<'tcx>,
205 pub i8: TyAndLayout<'tcx>,
206 pub i32: TyAndLayout<'tcx>,
207 pub isize: TyAndLayout<'tcx>,
208 pub u8: TyAndLayout<'tcx>,
209 pub u32: TyAndLayout<'tcx>,
210 pub usize: TyAndLayout<'tcx>,
213 impl<'mir, 'tcx: 'mir> PrimitiveLayouts<'tcx> {
214 fn new(layout_cx: LayoutCx<'tcx, TyCtxt<'tcx>>) -> Result<Self, LayoutError<'tcx>> {
216 unit: layout_cx.layout_of(layout_cx.tcx.mk_unit())?,
217 i8: layout_cx.layout_of(layout_cx.tcx.types.i8)?,
218 i32: layout_cx.layout_of(layout_cx.tcx.types.i32)?,
219 isize: layout_cx.layout_of(layout_cx.tcx.types.isize)?,
220 u8: layout_cx.layout_of(layout_cx.tcx.types.u8)?,
221 u32: layout_cx.layout_of(layout_cx.tcx.types.u32)?,
222 usize: layout_cx.layout_of(layout_cx.tcx.types.usize)?,
227 /// The machine itself.
228 pub struct Evaluator<'mir, 'tcx> {
229 /// Environment variables set by `setenv`.
230 /// Miri does not expose env vars from the host to the emulated program.
231 pub(crate) env_vars: EnvVars<'tcx>,
233 /// Program arguments (`Option` because we can only initialize them after creating the ecx).
234 /// These are *pointers* to argc/argv because macOS.
235 /// We also need the full command line as one string because of Windows.
236 pub(crate) argc: Option<Scalar<Tag>>,
237 pub(crate) argv: Option<Scalar<Tag>>,
238 pub(crate) cmd_line: Option<Scalar<Tag>>,
240 /// Last OS error location in memory. It is a 32-bit integer.
241 pub(crate) last_error: Option<MPlaceTy<'tcx, Tag>>,
244 pub(crate) tls: TlsData<'tcx>,
246 /// If enabled, the `env_vars` field is populated with the host env vars during initialization
247 /// and random number generation is delegated to the host.
248 pub(crate) communicate: bool,
250 /// Whether to enforce the validity invariant.
251 pub(crate) validate: bool,
253 pub(crate) file_handler: shims::posix::FileHandler,
254 pub(crate) dir_handler: shims::posix::DirHandler,
256 /// The temporary used for storing the argument of
257 /// the call to `miri_start_panic` (the panic payload) when unwinding.
258 /// This is pointer-sized, and matches the `Payload` type in `src/libpanic_unwind/miri.rs`.
259 pub(crate) panic_payload: Option<Scalar<Tag>>,
261 /// The "time anchor" for this machine's monotone clock (for `Instant` simulation).
262 pub(crate) time_anchor: Instant,
264 /// The set of threads.
265 pub(crate) threads: ThreadManager<'mir, 'tcx>,
267 /// Precomputed `TyLayout`s for primitive data types that are commonly used inside Miri.
268 pub(crate) layouts: PrimitiveLayouts<'tcx>,
270 /// Allocations that are considered roots of static memory (that may leak).
271 pub(crate) static_roots: Vec<AllocId>,
274 impl<'mir, 'tcx> Evaluator<'mir, 'tcx> {
278 layout_cx: LayoutCx<'tcx, TyCtxt<'tcx>>,
280 let layouts = PrimitiveLayouts::new(layout_cx)
281 .expect("Couldn't get layouts of primitive types");
283 // `env_vars` could be initialized properly here if `Memory` were available before
284 // calling this method.
285 env_vars: EnvVars::default(),
290 tls: TlsData::default(),
293 file_handler: Default::default(),
294 dir_handler: Default::default(),
296 time_anchor: Instant::now(),
298 threads: ThreadManager::default(),
299 static_roots: Vec::new(),
304 /// A rustc InterpCx for Miri.
305 pub type MiriEvalContext<'mir, 'tcx> = InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>;
307 /// A little trait that's useful to be inherited by extension traits.
308 pub trait MiriEvalContextExt<'mir, 'tcx> {
309 fn eval_context_ref<'a>(&'a self) -> &'a MiriEvalContext<'mir, 'tcx>;
310 fn eval_context_mut<'a>(&'a mut self) -> &'a mut MiriEvalContext<'mir, 'tcx>;
312 impl<'mir, 'tcx> MiriEvalContextExt<'mir, 'tcx> for MiriEvalContext<'mir, 'tcx> {
314 fn eval_context_ref(&self) -> &MiriEvalContext<'mir, 'tcx> {
318 fn eval_context_mut(&mut self) -> &mut MiriEvalContext<'mir, 'tcx> {
323 /// Machine hook implementations.
324 impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'mir, 'tcx> {
325 type MemoryKind = MiriMemoryKind;
327 type FrameExtra = FrameData<'tcx>;
328 type MemoryExtra = MemoryExtra;
329 type AllocExtra = AllocExtra;
330 type PointerTag = Tag;
331 type ExtraFnVal = Dlsym;
334 MonoHashMap<AllocId, (MemoryKind<MiriMemoryKind>, Allocation<Tag, Self::AllocExtra>)>;
336 const GLOBAL_KIND: Option<MiriMemoryKind> = Some(MiriMemoryKind::Global);
339 fn enforce_alignment(memory_extra: &MemoryExtra) -> bool {
340 memory_extra.check_alignment
344 fn enforce_validity(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool {
349 fn find_mir_or_eval_fn(
350 ecx: &mut InterpCx<'mir, 'tcx, Self>,
351 instance: ty::Instance<'tcx>,
352 args: &[OpTy<'tcx, Tag>],
353 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
354 unwind: Option<mir::BasicBlock>,
355 ) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
356 ecx.find_mir_or_eval_fn(instance, args, ret, unwind)
361 ecx: &mut InterpCx<'mir, 'tcx, Self>,
363 args: &[OpTy<'tcx, Tag>],
364 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
365 _unwind: Option<mir::BasicBlock>,
366 ) -> InterpResult<'tcx> {
367 ecx.call_dlsym(fn_val, args, ret)
372 ecx: &mut rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
373 instance: ty::Instance<'tcx>,
374 args: &[OpTy<'tcx, Tag>],
375 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
376 unwind: Option<mir::BasicBlock>,
377 ) -> InterpResult<'tcx> {
378 ecx.call_intrinsic(instance, args, ret, unwind)
383 ecx: &mut InterpCx<'mir, 'tcx, Self>,
384 msg: &mir::AssertMessage<'tcx>,
385 unwind: Option<mir::BasicBlock>,
386 ) -> InterpResult<'tcx> {
387 ecx.assert_panic(msg, unwind)
391 fn abort(_ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx, !> {
392 throw_machine_stop!(TerminationInfo::Abort(None))
397 ecx: &rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
399 left: ImmTy<'tcx, Tag>,
400 right: ImmTy<'tcx, Tag>,
401 ) -> InterpResult<'tcx, (Scalar<Tag>, bool, ty::Ty<'tcx>)> {
402 ecx.binary_ptr_op(bin_op, left, right)
406 ecx: &mut InterpCx<'mir, 'tcx, Self>,
407 dest: PlaceTy<'tcx, Tag>,
408 ) -> InterpResult<'tcx> {
409 trace!("box_alloc for {:?}", dest.layout.ty);
410 let layout = ecx.layout_of(dest.layout.ty.builtin_deref(false).unwrap().ty)?;
411 // First argument: `size`.
412 // (`0` is allowed here -- this is expected to be handled by the lang item).
413 let size = Scalar::from_machine_usize(layout.size.bytes(), ecx);
415 // Second argument: `align`.
416 let align = Scalar::from_machine_usize(layout.align.abi.bytes(), ecx);
418 // Call the `exchange_malloc` lang item.
419 let malloc = ecx.tcx.lang_items().exchange_malloc_fn().unwrap();
420 let malloc = ty::Instance::mono(ecx.tcx.tcx, malloc);
423 &[size.into(), align.into()],
425 // Don't do anything when we are done. The `statement()` function will increment
426 // the old stack frame's stmt counter to the next statement, which means that when
427 // `exchange_malloc` returns, we go on evaluating exactly where we want to be.
428 StackPopCleanup::None { cleanup: true },
433 fn thread_local_static_alloc_id(
434 ecx: &mut InterpCx<'mir, 'tcx, Self>,
436 ) -> InterpResult<'tcx, AllocId> {
437 ecx.get_or_create_thread_local_alloc_id(def_id)
440 fn extern_static_alloc_id(
441 memory: &Memory<'mir, 'tcx, Self>,
443 ) -> InterpResult<'tcx, AllocId> {
444 let attrs = memory.tcx.get_attrs(def_id);
445 let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
447 None => memory.tcx.item_name(def_id),
449 if let Some(&id) = memory.extra.extern_statics.get(&link_name) {
452 throw_unsup_format!("`extern` static {:?} is not supported by Miri", def_id)
456 fn init_allocation_extra<'b>(
457 memory_extra: &MemoryExtra,
459 alloc: Cow<'b, Allocation>,
460 kind: Option<MemoryKind<Self::MemoryKind>>,
461 ) -> (Cow<'b, Allocation<Self::PointerTag, Self::AllocExtra>>, Self::PointerTag) {
462 if Some(id) == memory_extra.tracked_alloc_id {
463 register_diagnostic(NonHaltingDiagnostic::CreatedAlloc(id));
466 let kind = kind.expect("we set our STATIC_KIND so this cannot be None");
467 let alloc = alloc.into_owned();
468 let (stacks, base_tag) =
469 if let Some(stacked_borrows) = &memory_extra.stacked_borrows {
470 let (stacks, base_tag) =
471 Stacks::new_allocation(id, alloc.size, Rc::clone(stacked_borrows), kind);
472 (Some(stacks), base_tag)
474 // No stacks, no tag.
475 (None, Tag::Untagged)
477 let mut stacked_borrows = memory_extra.stacked_borrows.as_ref().map(|sb| sb.borrow_mut());
478 let alloc: Allocation<Tag, Self::AllocExtra> = alloc.with_tags_and_extra(
480 if let Some(stacked_borrows) = &mut stacked_borrows {
481 // Only globals may already contain pointers at this point
482 assert_eq!(kind, MiriMemoryKind::Global.into());
483 stacked_borrows.global_base_ptr(alloc)
488 AllocExtra { stacked_borrows: stacks },
490 (Cow::Owned(alloc), base_tag)
494 fn before_deallocation(
495 memory_extra: &mut Self::MemoryExtra,
497 ) -> InterpResult<'tcx> {
498 if Some(id) == memory_extra.tracked_alloc_id {
499 register_diagnostic(NonHaltingDiagnostic::FreedAlloc(id));
506 fn tag_global_base_pointer(memory_extra: &MemoryExtra, id: AllocId) -> Self::PointerTag {
507 if let Some(stacked_borrows) = &memory_extra.stacked_borrows {
508 stacked_borrows.borrow_mut().global_base_ptr(id)
516 ecx: &mut InterpCx<'mir, 'tcx, Self>,
517 kind: mir::RetagKind,
518 place: PlaceTy<'tcx, Tag>,
519 ) -> InterpResult<'tcx> {
520 if ecx.memory.extra.stacked_borrows.is_some() {
521 ecx.retag(kind, place)
529 ecx: &mut InterpCx<'mir, 'tcx, Self>,
530 frame: Frame<'mir, 'tcx, Tag>,
531 ) -> InterpResult<'tcx, Frame<'mir, 'tcx, Tag, FrameData<'tcx>>> {
532 let stacked_borrows = ecx.memory.extra.stacked_borrows.as_ref();
533 let call_id = stacked_borrows.map_or(NonZeroU64::new(1).unwrap(), |stacked_borrows| {
534 stacked_borrows.borrow_mut().new_call()
536 let extra = FrameData { call_id, catch_unwind: None };
537 Ok(frame.with_extra(extra))
541 ecx: &'a InterpCx<'mir, 'tcx, Self>
542 ) -> &'a [Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>] {
543 ecx.active_thread_stack()
547 ecx: &'a mut InterpCx<'mir, 'tcx, Self>
548 ) -> &'a mut Vec<Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>> {
549 ecx.active_thread_stack_mut()
553 fn after_stack_push(ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx> {
554 if ecx.memory.extra.stacked_borrows.is_some() {
555 ecx.retag_return_place()
563 ecx: &mut InterpCx<'mir, 'tcx, Self>,
564 frame: Frame<'mir, 'tcx, Tag, FrameData<'tcx>>,
566 ) -> InterpResult<'tcx, StackPopJump> {
567 ecx.handle_stack_pop(frame.extra, unwinding)
572 memory: &Memory<'mir, 'tcx, Self>,
574 ) -> InterpResult<'tcx, Pointer<Self::PointerTag>> {
575 intptrcast::GlobalState::int_to_ptr(int, memory)
580 memory: &Memory<'mir, 'tcx, Self>,
581 ptr: Pointer<Self::PointerTag>,
582 ) -> InterpResult<'tcx, u64> {
583 intptrcast::GlobalState::ptr_to_int(ptr, memory)
587 impl AllocationExtra<Tag> for AllocExtra {
589 fn memory_read<'tcx>(
590 alloc: &Allocation<Tag, AllocExtra>,
593 ) -> InterpResult<'tcx> {
594 if let Some(stacked_borrows) = &alloc.extra.stacked_borrows {
595 stacked_borrows.memory_read(ptr, size)
602 fn memory_written<'tcx>(
603 alloc: &mut Allocation<Tag, AllocExtra>,
606 ) -> InterpResult<'tcx> {
607 if let Some(stacked_borrows) = &mut alloc.extra.stacked_borrows {
608 stacked_borrows.memory_written(ptr, size)
615 fn memory_deallocated<'tcx>(
616 alloc: &mut Allocation<Tag, AllocExtra>,
619 ) -> InterpResult<'tcx> {
620 if let Some(stacked_borrows) = &mut alloc.extra.stacked_borrows {
621 stacked_borrows.memory_deallocated(ptr, size)