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;
11 use rand::rngs::StdRng;
13 use rustc_data_structures::fx::FxHashMap;
14 use rustc_middle::mir;
15 use rustc_middle::ty::{
17 layout::{LayoutOf, Size},
21 use rustc_span::symbol::{sym, Symbol};
25 // Some global facts about the emulated machine.
26 pub const PAGE_SIZE: u64 = 4 * 1024; // FIXME: adjust to target architecture
27 pub const STACK_ADDR: u64 = 32 * PAGE_SIZE; // not really about the "stack", but where we start assigning integer addresses to allocations
28 pub const STACK_SIZE: u64 = 16 * PAGE_SIZE; // whatever
29 pub const NUM_CPUS: u64 = 1;
31 /// Extra data stored with each stack frame
33 pub struct FrameData<'tcx> {
34 /// Extra data for Stacked Borrows.
35 pub call_id: stacked_borrows::CallId,
37 /// If this is Some(), then this is a special "catch unwind" frame (the frame of `try_fn`
38 /// called by `try`). When this frame is popped during unwinding a panic,
39 /// we stop unwinding, use the `CatchUnwindData` to handle catching.
40 pub catch_unwind: Option<CatchUnwindData<'tcx>>,
43 /// Extra memory kinds
44 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
45 pub enum MiriMemoryKind {
46 /// `__rust_alloc` memory.
50 /// Windows `HeapAlloc` memory.
52 /// Memory for args, errno, extern statics and other parts of the machine-managed environment.
53 /// This memory may leak.
55 /// Memory for env vars. Separate from `Machine` because we clean it up and leak-check it.
57 /// Globals copied from `tcx`.
58 /// This memory may leak.
62 impl Into<MemoryKind<MiriMemoryKind>> for MiriMemoryKind {
64 fn into(self) -> MemoryKind<MiriMemoryKind> {
65 MemoryKind::Machine(self)
69 /// Extra per-allocation data
70 #[derive(Debug, Clone)]
71 pub struct AllocExtra {
72 /// Stacked Borrows state is only added if it is enabled.
73 pub stacked_borrows: Option<stacked_borrows::AllocExtra>,
76 /// Extra global memory data
77 #[derive(Clone, Debug)]
78 pub struct MemoryExtra {
79 pub stacked_borrows: Option<stacked_borrows::MemoryExtra>,
80 pub intptrcast: intptrcast::MemoryExtra,
82 /// Mapping extern static names to their canonical allocation.
83 extern_statics: FxHashMap<Symbol, AllocId>,
85 /// The random number generator used for resolving non-determinism.
86 /// Needs to be queried by ptr_to_int, hence needs interior mutability.
87 pub(crate) rng: RefCell<StdRng>,
89 /// An allocation ID to report when it is being allocated
90 /// (helps for debugging memory leaks).
91 tracked_alloc_id: Option<AllocId>,
95 pub fn new(rng: StdRng, stacked_borrows: bool, tracked_pointer_tag: Option<PtrId>, tracked_alloc_id: Option<AllocId>) -> Self {
96 let stacked_borrows = if stacked_borrows {
97 Some(Rc::new(RefCell::new(stacked_borrows::GlobalState::new(tracked_pointer_tag))))
103 intptrcast: Default::default(),
104 extern_statics: FxHashMap::default(),
105 rng: RefCell::new(rng),
110 fn add_extern_static<'tcx, 'mir>(
111 this: &mut MiriEvalContext<'mir, 'tcx>,
115 let ptr = ptr.assert_ptr();
116 assert_eq!(ptr.offset, Size::ZERO);
120 .insert(Symbol::intern(name), ptr.alloc_id)
124 /// Sets up the "extern statics" for this machine.
125 pub fn init_extern_statics<'tcx, 'mir>(
126 this: &mut MiriEvalContext<'mir, 'tcx>,
127 ) -> InterpResult<'tcx> {
128 match this.tcx.sess.target.target.target_os.as_str() {
130 // "__cxa_thread_atexit_impl"
131 // This should be all-zero, pointer-sized.
132 let layout = this.layout_of(this.tcx.types.usize)?;
133 let place = this.allocate(layout, MiriMemoryKind::Machine.into());
134 this.write_scalar(Scalar::from_machine_usize(0, this), place.into())?;
135 Self::add_extern_static(this, "__cxa_thread_atexit_impl", place.ptr);
137 Self::add_extern_static(this, "environ", this.machine.env_vars.environ.unwrap().ptr);
141 // This is some obscure hack that is part of the Windows TLS story. It's a `u8`.
142 let layout = this.layout_of(this.tcx.types.u8)?;
143 let place = this.allocate(layout, MiriMemoryKind::Machine.into());
144 this.write_scalar(Scalar::from_u8(0), place.into())?;
145 Self::add_extern_static(this, "_tls_used", place.ptr);
147 _ => {} // No "extern statics" supported on this target
153 /// The machine itself.
154 pub struct Evaluator<'tcx> {
155 /// Environment variables set by `setenv`.
156 /// Miri does not expose env vars from the host to the emulated program.
157 pub(crate) env_vars: EnvVars<'tcx>,
159 /// Program arguments (`Option` because we can only initialize them after creating the ecx).
160 /// These are *pointers* to argc/argv because macOS.
161 /// We also need the full command line as one string because of Windows.
162 pub(crate) argc: Option<Scalar<Tag>>,
163 pub(crate) argv: Option<Scalar<Tag>>,
164 pub(crate) cmd_line: Option<Scalar<Tag>>,
166 /// Last OS error location in memory. It is a 32-bit integer.
167 pub(crate) last_error: Option<MPlaceTy<'tcx, Tag>>,
170 pub(crate) tls: TlsData<'tcx>,
172 /// If enabled, the `env_vars` field is populated with the host env vars during initialization
173 /// and random number generation is delegated to the host.
174 pub(crate) communicate: bool,
176 /// Whether to enforce the validity invariant.
177 pub(crate) validate: bool,
179 pub(crate) file_handler: FileHandler,
180 pub(crate) dir_handler: DirHandler,
182 /// The temporary used for storing the argument of
183 /// the call to `miri_start_panic` (the panic payload) when unwinding.
184 /// This is pointer-sized, and matches the `Payload` type in `src/libpanic_unwind/miri.rs`.
185 pub(crate) panic_payload: Option<Scalar<Tag>>,
187 /// The "time anchor" for this machine's monotone clock (for `Instant` simulation).
188 pub(crate) time_anchor: Instant,
191 impl<'tcx> Evaluator<'tcx> {
192 pub(crate) fn new(communicate: bool, validate: bool) -> Self {
194 // `env_vars` could be initialized properly here if `Memory` were available before
195 // calling this method.
196 env_vars: EnvVars::default(),
201 tls: TlsData::default(),
204 file_handler: Default::default(),
205 dir_handler: Default::default(),
207 time_anchor: Instant::now(),
212 /// A rustc InterpCx for Miri.
213 pub type MiriEvalContext<'mir, 'tcx> = InterpCx<'mir, 'tcx, Evaluator<'tcx>>;
215 /// A little trait that's useful to be inherited by extension traits.
216 pub trait MiriEvalContextExt<'mir, 'tcx> {
217 fn eval_context_ref<'a>(&'a self) -> &'a MiriEvalContext<'mir, 'tcx>;
218 fn eval_context_mut<'a>(&'a mut self) -> &'a mut MiriEvalContext<'mir, 'tcx>;
220 impl<'mir, 'tcx> MiriEvalContextExt<'mir, 'tcx> for MiriEvalContext<'mir, 'tcx> {
222 fn eval_context_ref(&self) -> &MiriEvalContext<'mir, 'tcx> {
226 fn eval_context_mut(&mut self) -> &mut MiriEvalContext<'mir, 'tcx> {
231 /// Machine hook implementations.
232 impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'tcx> {
233 type MemoryKind = MiriMemoryKind;
235 type FrameExtra = FrameData<'tcx>;
236 type MemoryExtra = MemoryExtra;
237 type AllocExtra = AllocExtra;
238 type PointerTag = Tag;
239 type ExtraFnVal = Dlsym;
242 MonoHashMap<AllocId, (MemoryKind<MiriMemoryKind>, Allocation<Tag, Self::AllocExtra>)>;
244 const GLOBAL_KIND: Option<MiriMemoryKind> = Some(MiriMemoryKind::Global);
246 const CHECK_ALIGN: bool = true;
249 fn enforce_validity(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool {
254 fn find_mir_or_eval_fn(
255 ecx: &mut InterpCx<'mir, 'tcx, Self>,
256 instance: ty::Instance<'tcx>,
257 args: &[OpTy<'tcx, Tag>],
258 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
259 unwind: Option<mir::BasicBlock>,
260 ) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
261 ecx.find_mir_or_eval_fn(instance, args, ret, unwind)
266 ecx: &mut InterpCx<'mir, 'tcx, Self>,
268 args: &[OpTy<'tcx, Tag>],
269 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
270 _unwind: Option<mir::BasicBlock>,
271 ) -> InterpResult<'tcx> {
272 ecx.call_dlsym(fn_val, args, ret)
277 ecx: &mut rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
278 instance: ty::Instance<'tcx>,
279 args: &[OpTy<'tcx, Tag>],
280 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
281 unwind: Option<mir::BasicBlock>,
282 ) -> InterpResult<'tcx> {
283 ecx.call_intrinsic(instance, args, ret, unwind)
288 ecx: &mut InterpCx<'mir, 'tcx, Self>,
289 msg: &mir::AssertMessage<'tcx>,
290 unwind: Option<mir::BasicBlock>,
291 ) -> InterpResult<'tcx> {
292 ecx.assert_panic(msg, unwind)
296 fn abort(_ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx, !> {
297 throw_machine_stop!(TerminationInfo::Abort(None))
302 ecx: &rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
304 left: ImmTy<'tcx, Tag>,
305 right: ImmTy<'tcx, Tag>,
306 ) -> InterpResult<'tcx, (Scalar<Tag>, bool, Ty<'tcx>)> {
307 ecx.binary_ptr_op(bin_op, left, right)
311 ecx: &mut InterpCx<'mir, 'tcx, Self>,
312 dest: PlaceTy<'tcx, Tag>,
313 ) -> InterpResult<'tcx> {
314 trace!("box_alloc for {:?}", dest.layout.ty);
315 let layout = ecx.layout_of(dest.layout.ty.builtin_deref(false).unwrap().ty)?;
316 // First argument: `size`.
317 // (`0` is allowed here -- this is expected to be handled by the lang item).
318 let size = Scalar::from_machine_usize(layout.size.bytes(), ecx);
320 // Second argument: `align`.
321 let align = Scalar::from_machine_usize(layout.align.abi.bytes(), ecx);
323 // Call the `exchange_malloc` lang item.
324 let malloc = ecx.tcx.lang_items().exchange_malloc_fn().unwrap();
325 let malloc = ty::Instance::mono(ecx.tcx.tcx, malloc);
328 &[size.into(), align.into()],
330 // Don't do anything when we are done. The `statement()` function will increment
331 // the old stack frame's stmt counter to the next statement, which means that when
332 // `exchange_malloc` returns, we go on evaluating exactly where we want to be.
333 StackPopCleanup::None { cleanup: true },
338 fn canonical_alloc_id(mem: &Memory<'mir, 'tcx, Self>, id: AllocId) -> AllocId {
340 // Figure out if this is an extern static, and if yes, which one.
341 let def_id = match tcx.alloc_map.lock().get(id) {
342 Some(GlobalAlloc::Static(def_id)) if tcx.is_foreign_item(def_id) => def_id,
344 // No need to canonicalize anything.
348 let attrs = tcx.get_attrs(def_id);
349 let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
351 None => tcx.item_name(def_id),
353 // Check if we know this one.
354 if let Some(canonical_id) = mem.extra.extern_statics.get(&link_name) {
355 trace!("canonical_alloc_id: {:?} ({}) -> {:?}", id, link_name, canonical_id);
358 // Return original id; `Memory::get_static_alloc` will throw an error.
363 fn init_allocation_extra<'b>(
364 memory_extra: &MemoryExtra,
366 alloc: Cow<'b, Allocation>,
367 kind: Option<MemoryKind<Self::MemoryKind>>,
368 ) -> (Cow<'b, Allocation<Self::PointerTag, Self::AllocExtra>>, Self::PointerTag) {
369 if Some(id) == memory_extra.tracked_alloc_id {
370 register_diagnostic(NonHaltingDiagnostic::CreatedAlloc(id));
373 let kind = kind.expect("we set our STATIC_KIND so this cannot be None");
374 let alloc = alloc.into_owned();
375 let (stacks, base_tag) =
376 if let Some(stacked_borrows) = memory_extra.stacked_borrows.as_ref() {
377 let (stacks, base_tag) =
378 Stacks::new_allocation(id, alloc.size, Rc::clone(stacked_borrows), kind);
379 (Some(stacks), base_tag)
381 // No stacks, no tag.
382 (None, Tag::Untagged)
384 let mut stacked_borrows = memory_extra.stacked_borrows.as_ref().map(|sb| sb.borrow_mut());
385 let alloc: Allocation<Tag, Self::AllocExtra> = alloc.with_tags_and_extra(
387 if let Some(stacked_borrows) = stacked_borrows.as_mut() {
388 // Only globals may already contain pointers at this point
389 assert_eq!(kind, MiriMemoryKind::Global.into());
390 stacked_borrows.global_base_ptr(alloc)
395 AllocExtra { stacked_borrows: stacks },
397 (Cow::Owned(alloc), base_tag)
401 fn tag_global_base_pointer(memory_extra: &MemoryExtra, id: AllocId) -> Self::PointerTag {
402 if let Some(stacked_borrows) = memory_extra.stacked_borrows.as_ref() {
403 stacked_borrows.borrow_mut().global_base_ptr(id)
411 ecx: &mut InterpCx<'mir, 'tcx, Self>,
412 kind: mir::RetagKind,
413 place: PlaceTy<'tcx, Tag>,
414 ) -> InterpResult<'tcx> {
415 if ecx.memory.extra.stacked_borrows.is_none() {
419 ecx.retag(kind, place)
424 fn stack_push(ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx, FrameData<'tcx>> {
425 let stacked_borrows = ecx.memory.extra.stacked_borrows.as_ref();
426 let call_id = stacked_borrows.map_or(NonZeroU64::new(1).unwrap(), |stacked_borrows| {
427 stacked_borrows.borrow_mut().new_call()
429 Ok(FrameData { call_id, catch_unwind: None })
434 ecx: &mut InterpCx<'mir, 'tcx, Self>,
435 extra: FrameData<'tcx>,
437 ) -> InterpResult<'tcx, StackPopJump> {
438 ecx.handle_stack_pop(extra, unwinding)
443 memory: &Memory<'mir, 'tcx, Self>,
445 ) -> InterpResult<'tcx, Pointer<Self::PointerTag>> {
446 intptrcast::GlobalState::int_to_ptr(int, memory)
451 memory: &Memory<'mir, 'tcx, Self>,
452 ptr: Pointer<Self::PointerTag>,
453 ) -> InterpResult<'tcx, u64> {
454 intptrcast::GlobalState::ptr_to_int(ptr, memory)
458 impl AllocationExtra<Tag> for AllocExtra {
460 fn memory_read<'tcx>(
461 alloc: &Allocation<Tag, AllocExtra>,
464 ) -> InterpResult<'tcx> {
465 if let Some(ref stacked_borrows) = alloc.extra.stacked_borrows {
466 stacked_borrows.memory_read(ptr, size)
473 fn memory_written<'tcx>(
474 alloc: &mut Allocation<Tag, AllocExtra>,
477 ) -> InterpResult<'tcx> {
478 if let Some(ref mut stacked_borrows) = alloc.extra.stacked_borrows {
479 stacked_borrows.memory_written(ptr, size)
486 fn memory_deallocated<'tcx>(
487 alloc: &mut Allocation<Tag, AllocExtra>,
490 ) -> InterpResult<'tcx> {
491 if let Some(ref mut stacked_borrows) = alloc.extra.stacked_borrows {
492 stacked_borrows.memory_deallocated(ptr, size)
499 impl MayLeak for MiriMemoryKind {
501 fn may_leak(self) -> bool {
502 use self::MiriMemoryKind::*;
504 Rust | C | WinHeap | Env => false,
505 Machine | Global => true,