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.
70 impl Into<MemoryKind<MiriMemoryKind>> for MiriMemoryKind {
72 fn into(self) -> MemoryKind<MiriMemoryKind> {
73 MemoryKind::Machine(self)
77 impl MayLeak for MiriMemoryKind {
79 fn may_leak(self) -> bool {
80 use self::MiriMemoryKind::*;
82 Rust | C | WinHeap | Env => false,
83 Machine | Global | ExternGlobal => true,
88 impl fmt::Display for MiriMemoryKind {
89 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
90 use self::MiriMemoryKind::*;
92 Rust => write!(f, "Rust heap"),
93 C => write!(f, "C heap"),
94 WinHeap => write!(f, "Windows heap"),
95 Machine => write!(f, "machine-managed memory"),
96 Env => write!(f, "environment variable"),
97 Global => write!(f, "global"),
98 ExternGlobal => write!(f, "extern global"),
103 /// Extra per-allocation data
104 #[derive(Debug, Clone)]
105 pub struct AllocExtra {
106 /// Stacked Borrows state is only added if it is enabled.
107 pub stacked_borrows: Option<stacked_borrows::AllocExtra>,
110 /// Extra global memory data
111 #[derive(Clone, Debug)]
112 pub struct MemoryExtra {
113 pub stacked_borrows: Option<stacked_borrows::MemoryExtra>,
114 pub intptrcast: intptrcast::MemoryExtra,
116 /// Mapping extern static names to their canonical allocation.
117 extern_statics: FxHashMap<Symbol, AllocId>,
119 /// The random number generator used for resolving non-determinism.
120 /// Needs to be queried by ptr_to_int, hence needs interior mutability.
121 pub(crate) rng: RefCell<StdRng>,
123 /// An allocation ID to report when it is being allocated
124 /// (helps for debugging memory leaks and use after free bugs).
125 tracked_alloc_id: Option<AllocId>,
127 /// Controls whether alignment of memory accesses is being checked.
128 check_alignment: bool,
134 stacked_borrows: bool,
135 tracked_pointer_tag: Option<PtrId>,
136 tracked_call_id: Option<CallId>,
137 tracked_alloc_id: Option<AllocId>,
138 check_alignment: bool,
140 let stacked_borrows = if stacked_borrows {
141 Some(Rc::new(RefCell::new(stacked_borrows::GlobalState::new(tracked_pointer_tag, tracked_call_id))))
147 intptrcast: Default::default(),
148 extern_statics: FxHashMap::default(),
149 rng: RefCell::new(rng),
155 fn add_extern_static<'tcx, 'mir>(
156 this: &mut MiriEvalContext<'mir, 'tcx>,
160 let ptr = ptr.assert_ptr();
161 assert_eq!(ptr.offset, Size::ZERO);
165 .insert(Symbol::intern(name), ptr.alloc_id)
169 /// Sets up the "extern statics" for this machine.
170 pub fn init_extern_statics<'tcx, 'mir>(
171 this: &mut MiriEvalContext<'mir, 'tcx>,
172 ) -> InterpResult<'tcx> {
173 match this.tcx.sess.target.target.target_os.as_str() {
175 // "__cxa_thread_atexit_impl"
176 // This should be all-zero, pointer-sized.
177 let layout = this.machine.layouts.usize;
178 let place = this.allocate(layout, MiriMemoryKind::ExternGlobal.into());
179 this.write_scalar(Scalar::from_machine_usize(0, this), place.into())?;
180 Self::add_extern_static(this, "__cxa_thread_atexit_impl", place.ptr);
182 Self::add_extern_static(this, "environ", this.machine.env_vars.environ.unwrap().ptr);
186 // This is some obscure hack that is part of the Windows TLS story. It's a `u8`.
187 let layout = this.machine.layouts.u8;
188 let place = this.allocate(layout, MiriMemoryKind::ExternGlobal.into());
189 this.write_scalar(Scalar::from_u8(0), place.into())?;
190 Self::add_extern_static(this, "_tls_used", place.ptr);
192 _ => {} // No "extern statics" supported on this target
198 /// Precomputed layouts of primitive types
199 pub struct PrimitiveLayouts<'tcx> {
200 pub unit: TyAndLayout<'tcx>,
201 pub i8: TyAndLayout<'tcx>,
202 pub i32: TyAndLayout<'tcx>,
203 pub isize: TyAndLayout<'tcx>,
204 pub u8: TyAndLayout<'tcx>,
205 pub u32: TyAndLayout<'tcx>,
206 pub usize: TyAndLayout<'tcx>,
209 impl<'mir, 'tcx: 'mir> PrimitiveLayouts<'tcx> {
210 fn new(layout_cx: LayoutCx<'tcx, TyCtxt<'tcx>>) -> Result<Self, LayoutError<'tcx>> {
212 unit: layout_cx.layout_of(layout_cx.tcx.mk_unit())?,
213 i8: layout_cx.layout_of(layout_cx.tcx.types.i8)?,
214 i32: layout_cx.layout_of(layout_cx.tcx.types.i32)?,
215 isize: layout_cx.layout_of(layout_cx.tcx.types.isize)?,
216 u8: layout_cx.layout_of(layout_cx.tcx.types.u8)?,
217 u32: layout_cx.layout_of(layout_cx.tcx.types.u32)?,
218 usize: layout_cx.layout_of(layout_cx.tcx.types.usize)?,
223 /// The machine itself.
224 pub struct Evaluator<'mir, 'tcx> {
225 /// Environment variables set by `setenv`.
226 /// Miri does not expose env vars from the host to the emulated program.
227 pub(crate) env_vars: EnvVars<'tcx>,
229 /// Program arguments (`Option` because we can only initialize them after creating the ecx).
230 /// These are *pointers* to argc/argv because macOS.
231 /// We also need the full command line as one string because of Windows.
232 pub(crate) argc: Option<Scalar<Tag>>,
233 pub(crate) argv: Option<Scalar<Tag>>,
234 pub(crate) cmd_line: Option<Scalar<Tag>>,
236 /// Last OS error location in memory. It is a 32-bit integer.
237 pub(crate) last_error: Option<MPlaceTy<'tcx, Tag>>,
240 pub(crate) tls: TlsData<'tcx>,
242 /// If enabled, the `env_vars` field is populated with the host env vars during initialization
243 /// and random number generation is delegated to the host.
244 pub(crate) communicate: bool,
246 /// Whether to enforce the validity invariant.
247 pub(crate) validate: bool,
249 pub(crate) file_handler: shims::posix::FileHandler<'tcx>,
250 pub(crate) dir_handler: shims::posix::DirHandler,
252 /// The temporary used for storing the argument of
253 /// the call to `miri_start_panic` (the panic payload) when unwinding.
254 /// This is pointer-sized, and matches the `Payload` type in `src/libpanic_unwind/miri.rs`.
255 pub(crate) panic_payload: Option<Scalar<Tag>>,
257 /// The "time anchor" for this machine's monotone clock (for `Instant` simulation).
258 pub(crate) time_anchor: Instant,
260 /// The set of threads.
261 pub(crate) threads: ThreadManager<'mir, 'tcx>,
263 /// Precomputed `TyLayout`s for primitive data types that are commonly used inside Miri.
264 pub(crate) layouts: PrimitiveLayouts<'tcx>,
266 /// Allocations that are considered roots of static memory (that may leak).
267 pub(crate) static_roots: Vec<AllocId>,
270 impl<'mir, 'tcx> Evaluator<'mir, 'tcx> {
274 layout_cx: LayoutCx<'tcx, TyCtxt<'tcx>>,
276 let layouts = PrimitiveLayouts::new(layout_cx)
277 .expect("Couldn't get layouts of primitive types");
279 // `env_vars` could be initialized properly here if `Memory` were available before
280 // calling this method.
281 env_vars: EnvVars::default(),
286 tls: TlsData::default(),
289 file_handler: Default::default(),
290 dir_handler: Default::default(),
292 time_anchor: Instant::now(),
294 threads: ThreadManager::default(),
295 static_roots: Vec::new(),
300 /// A rustc InterpCx for Miri.
301 pub type MiriEvalContext<'mir, 'tcx> = InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>;
303 /// A little trait that's useful to be inherited by extension traits.
304 pub trait MiriEvalContextExt<'mir, 'tcx> {
305 fn eval_context_ref<'a>(&'a self) -> &'a MiriEvalContext<'mir, 'tcx>;
306 fn eval_context_mut<'a>(&'a mut self) -> &'a mut MiriEvalContext<'mir, 'tcx>;
308 impl<'mir, 'tcx> MiriEvalContextExt<'mir, 'tcx> for MiriEvalContext<'mir, 'tcx> {
310 fn eval_context_ref(&self) -> &MiriEvalContext<'mir, 'tcx> {
314 fn eval_context_mut(&mut self) -> &mut MiriEvalContext<'mir, 'tcx> {
319 /// Machine hook implementations.
320 impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'mir, 'tcx> {
321 type MemoryKind = MiriMemoryKind;
323 type FrameExtra = FrameData<'tcx>;
324 type MemoryExtra = MemoryExtra;
325 type AllocExtra = AllocExtra;
326 type PointerTag = Tag;
327 type ExtraFnVal = Dlsym;
330 MonoHashMap<AllocId, (MemoryKind<MiriMemoryKind>, Allocation<Tag, Self::AllocExtra>)>;
332 const GLOBAL_KIND: Option<MiriMemoryKind> = Some(MiriMemoryKind::Global);
335 fn enforce_alignment(memory_extra: &MemoryExtra) -> bool {
336 memory_extra.check_alignment
340 fn enforce_validity(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool {
345 fn find_mir_or_eval_fn(
346 ecx: &mut InterpCx<'mir, 'tcx, Self>,
347 instance: ty::Instance<'tcx>,
348 args: &[OpTy<'tcx, Tag>],
349 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
350 unwind: Option<mir::BasicBlock>,
351 ) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
352 ecx.find_mir_or_eval_fn(instance, args, ret, unwind)
357 ecx: &mut InterpCx<'mir, 'tcx, Self>,
359 args: &[OpTy<'tcx, Tag>],
360 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
361 _unwind: Option<mir::BasicBlock>,
362 ) -> InterpResult<'tcx> {
363 ecx.call_dlsym(fn_val, args, ret)
368 ecx: &mut rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
369 instance: ty::Instance<'tcx>,
370 args: &[OpTy<'tcx, Tag>],
371 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
372 unwind: Option<mir::BasicBlock>,
373 ) -> InterpResult<'tcx> {
374 ecx.call_intrinsic(instance, args, ret, unwind)
379 ecx: &mut InterpCx<'mir, 'tcx, Self>,
380 msg: &mir::AssertMessage<'tcx>,
381 unwind: Option<mir::BasicBlock>,
382 ) -> InterpResult<'tcx> {
383 ecx.assert_panic(msg, unwind)
387 fn abort(_ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx, !> {
388 throw_machine_stop!(TerminationInfo::Abort(None))
393 ecx: &rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
395 left: ImmTy<'tcx, Tag>,
396 right: ImmTy<'tcx, Tag>,
397 ) -> InterpResult<'tcx, (Scalar<Tag>, bool, ty::Ty<'tcx>)> {
398 ecx.binary_ptr_op(bin_op, left, right)
402 ecx: &mut InterpCx<'mir, 'tcx, Self>,
403 dest: PlaceTy<'tcx, Tag>,
404 ) -> InterpResult<'tcx> {
405 trace!("box_alloc for {:?}", dest.layout.ty);
406 let layout = ecx.layout_of(dest.layout.ty.builtin_deref(false).unwrap().ty)?;
407 // First argument: `size`.
408 // (`0` is allowed here -- this is expected to be handled by the lang item).
409 let size = Scalar::from_machine_usize(layout.size.bytes(), ecx);
411 // Second argument: `align`.
412 let align = Scalar::from_machine_usize(layout.align.abi.bytes(), ecx);
414 // Call the `exchange_malloc` lang item.
415 let malloc = ecx.tcx.lang_items().exchange_malloc_fn().unwrap();
416 let malloc = ty::Instance::mono(ecx.tcx.tcx, malloc);
419 &[size.into(), align.into()],
421 // Don't do anything when we are done. The `statement()` function will increment
422 // the old stack frame's stmt counter to the next statement, which means that when
423 // `exchange_malloc` returns, we go on evaluating exactly where we want to be.
424 StackPopCleanup::None { cleanup: true },
429 fn thread_local_alloc_id(
430 ecx: &mut InterpCx<'mir, 'tcx, Self>,
432 ) -> InterpResult<'tcx, AllocId> {
433 ecx.get_or_create_thread_local_alloc_id(def_id)
436 fn adjust_global_const(
437 ecx: &InterpCx<'mir, 'tcx, Self>,
438 mut val: mir::interpret::ConstValue<'tcx>,
439 ) -> InterpResult<'tcx, mir::interpret::ConstValue<'tcx>> {
440 // FIXME: Remove this, do The Right Thing in `thread_local_alloc_id` instead.
441 ecx.remap_thread_local_alloc_ids(&mut val)?;
445 fn canonical_alloc_id(mem: &Memory<'mir, 'tcx, Self>, id: AllocId) -> AllocId {
447 // Figure out if this is an extern static, and if yes, which one.
448 let def_id = match tcx.get_global_alloc(id) {
449 Some(GlobalAlloc::Static(def_id)) if tcx.is_foreign_item(def_id) => def_id,
451 // No need to canonicalize anything.
455 let attrs = tcx.get_attrs(def_id);
456 let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
458 None => tcx.item_name(def_id),
460 // Check if we know this one.
461 if let Some(canonical_id) = mem.extra.extern_statics.get(&link_name) {
462 trace!("canonical_alloc_id: {:?} ({}) -> {:?}", id, link_name, canonical_id);
465 // Return original id; `Memory::get_static_alloc` will throw an error.
470 fn init_allocation_extra<'b>(
471 memory_extra: &MemoryExtra,
473 alloc: Cow<'b, Allocation>,
474 kind: Option<MemoryKind<Self::MemoryKind>>,
475 ) -> (Cow<'b, Allocation<Self::PointerTag, Self::AllocExtra>>, Self::PointerTag) {
476 if Some(id) == memory_extra.tracked_alloc_id {
477 register_diagnostic(NonHaltingDiagnostic::CreatedAlloc(id));
480 let kind = kind.expect("we set our STATIC_KIND so this cannot be None");
481 let alloc = alloc.into_owned();
482 let (stacks, base_tag) =
483 if let Some(stacked_borrows) = &memory_extra.stacked_borrows {
484 let (stacks, base_tag) =
485 Stacks::new_allocation(id, alloc.size, Rc::clone(stacked_borrows), kind);
486 (Some(stacks), base_tag)
488 // No stacks, no tag.
489 (None, Tag::Untagged)
491 let mut stacked_borrows = memory_extra.stacked_borrows.as_ref().map(|sb| sb.borrow_mut());
492 let alloc: Allocation<Tag, Self::AllocExtra> = alloc.with_tags_and_extra(
494 if let Some(stacked_borrows) = &mut stacked_borrows {
495 // Only globals may already contain pointers at this point
496 assert_eq!(kind, MiriMemoryKind::Global.into());
497 stacked_borrows.global_base_ptr(alloc)
502 AllocExtra { stacked_borrows: stacks },
504 (Cow::Owned(alloc), base_tag)
508 fn before_deallocation(
509 memory_extra: &mut Self::MemoryExtra,
511 ) -> InterpResult<'tcx> {
512 if Some(id) == memory_extra.tracked_alloc_id {
513 register_diagnostic(NonHaltingDiagnostic::FreedAlloc(id));
520 fn tag_global_base_pointer(memory_extra: &MemoryExtra, id: AllocId) -> Self::PointerTag {
521 if let Some(stacked_borrows) = &memory_extra.stacked_borrows {
522 stacked_borrows.borrow_mut().global_base_ptr(id)
530 ecx: &mut InterpCx<'mir, 'tcx, Self>,
531 kind: mir::RetagKind,
532 place: PlaceTy<'tcx, Tag>,
533 ) -> InterpResult<'tcx> {
534 if ecx.memory.extra.stacked_borrows.is_some() {
535 ecx.retag(kind, place)
543 ecx: &mut InterpCx<'mir, 'tcx, Self>,
544 frame: Frame<'mir, 'tcx, Tag>,
545 ) -> InterpResult<'tcx, Frame<'mir, 'tcx, Tag, FrameData<'tcx>>> {
546 let stacked_borrows = ecx.memory.extra.stacked_borrows.as_ref();
547 let call_id = stacked_borrows.map_or(NonZeroU64::new(1).unwrap(), |stacked_borrows| {
548 stacked_borrows.borrow_mut().new_call()
550 let extra = FrameData { call_id, catch_unwind: None };
551 Ok(frame.with_extra(extra))
555 ecx: &'a InterpCx<'mir, 'tcx, Self>
556 ) -> &'a [Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>] {
557 ecx.active_thread_stack()
561 ecx: &'a mut InterpCx<'mir, 'tcx, Self>
562 ) -> &'a mut Vec<Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>> {
563 ecx.active_thread_stack_mut()
567 fn after_stack_push(ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx> {
568 if ecx.memory.extra.stacked_borrows.is_some() {
569 ecx.retag_return_place()
577 ecx: &mut InterpCx<'mir, 'tcx, Self>,
578 frame: Frame<'mir, 'tcx, Tag, FrameData<'tcx>>,
580 ) -> InterpResult<'tcx, StackPopJump> {
581 ecx.handle_stack_pop(frame.extra, unwinding)
586 memory: &Memory<'mir, 'tcx, Self>,
588 ) -> InterpResult<'tcx, Pointer<Self::PointerTag>> {
589 intptrcast::GlobalState::int_to_ptr(int, memory)
594 memory: &Memory<'mir, 'tcx, Self>,
595 ptr: Pointer<Self::PointerTag>,
596 ) -> InterpResult<'tcx, u64> {
597 intptrcast::GlobalState::ptr_to_int(ptr, memory)
601 impl AllocationExtra<Tag> for AllocExtra {
603 fn memory_read<'tcx>(
604 alloc: &Allocation<Tag, AllocExtra>,
607 ) -> InterpResult<'tcx> {
608 if let Some(stacked_borrows) = &alloc.extra.stacked_borrows {
609 stacked_borrows.memory_read(ptr, size)
616 fn memory_written<'tcx>(
617 alloc: &mut Allocation<Tag, AllocExtra>,
620 ) -> InterpResult<'tcx> {
621 if let Some(stacked_borrows) = &mut alloc.extra.stacked_borrows {
622 stacked_borrows.memory_written(ptr, size)
629 fn memory_deallocated<'tcx>(
630 alloc: &mut Allocation<Tag, AllocExtra>,
633 ) -> InterpResult<'tcx> {
634 if let Some(stacked_borrows) = &mut alloc.extra.stacked_borrows {
635 stacked_borrows.memory_deallocated(ptr, size)