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;
10 use rand::rngs::StdRng;
12 use rustc_data_structures::fx::FxHashMap;
16 layout::{LayoutOf, Size},
20 use rustc_span::{source_map::Span, symbol::{sym, Symbol}};
24 // Some global facts about the emulated machine.
25 pub const PAGE_SIZE: u64 = 4 * 1024; // FIXME: adjust to target architecture
26 pub const STACK_ADDR: u64 = 32 * PAGE_SIZE; // not really about the "stack", but where we start assigning integer addresses to allocations
27 pub const STACK_SIZE: u64 = 16 * PAGE_SIZE; // whatever
28 pub const NUM_CPUS: u64 = 1;
30 /// Extra data stored with each stack frame
32 pub struct FrameData<'tcx> {
33 /// Extra data for Stacked Borrows.
34 pub call_id: stacked_borrows::CallId,
36 /// If this is Some(), then this is a special "catch unwind" frame (the frame of `try_fn`
37 /// called by `try`). When this frame is popped during unwinding a panic,
38 /// we stop unwinding, use the `CatchUnwindData` to handle catching.
39 pub catch_unwind: Option<CatchUnwindData<'tcx>>,
42 /// Extra memory kinds
43 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
44 pub enum MiriMemoryKind {
45 /// `__rust_alloc` memory.
49 /// Windows `HeapAlloc` memory.
51 /// Memory for args, errno, extern statics and other parts of the machine-managed environment.
52 /// This memory may leak.
54 /// Memory for env vars. Separate from `Machine` because we clean it up and leak-check it.
56 /// Globals copied from `tcx`.
57 /// This memory may leak.
61 impl Into<MemoryKind<MiriMemoryKind>> for MiriMemoryKind {
63 fn into(self) -> MemoryKind<MiriMemoryKind> {
64 MemoryKind::Machine(self)
68 /// Extra per-allocation data
69 #[derive(Debug, Clone)]
70 pub struct AllocExtra {
71 /// Stacked Borrows state is only added if it is enabled.
72 pub stacked_borrows: Option<stacked_borrows::AllocExtra>,
75 /// Extra global memory data
76 #[derive(Clone, Debug)]
77 pub struct MemoryExtra {
78 pub stacked_borrows: Option<stacked_borrows::MemoryExtra>,
79 pub intptrcast: intptrcast::MemoryExtra,
81 /// Mapping extern static names to their canonical allocation.
82 extern_statics: FxHashMap<Symbol, AllocId>,
84 /// The random number generator used for resolving non-determinism.
85 /// Needs to be queried by ptr_to_int, hence needs interior mutability.
86 pub(crate) rng: RefCell<StdRng>,
88 /// An allocation ID to report when it is being allocated
89 /// (helps for debugging memory leaks).
90 tracked_alloc_id: Option<AllocId>,
94 pub fn new(rng: StdRng, stacked_borrows: bool, tracked_pointer_tag: Option<PtrId>, tracked_alloc_id: Option<AllocId>) -> Self {
95 let stacked_borrows = if stacked_borrows {
96 Some(Rc::new(RefCell::new(stacked_borrows::GlobalState::new(tracked_pointer_tag))))
102 intptrcast: Default::default(),
103 extern_statics: FxHashMap::default(),
104 rng: RefCell::new(rng),
109 fn add_extern_static<'tcx, 'mir>(
110 this: &mut MiriEvalContext<'mir, 'tcx>,
114 let ptr = ptr.assert_ptr();
115 assert_eq!(ptr.offset, Size::ZERO);
119 .insert(Symbol::intern(name), ptr.alloc_id)
123 /// Sets up the "extern statics" for this machine.
124 pub fn init_extern_statics<'tcx, 'mir>(
125 this: &mut MiriEvalContext<'mir, 'tcx>,
126 ) -> InterpResult<'tcx> {
127 match this.tcx.sess.target.target.target_os.as_str() {
129 // "__cxa_thread_atexit_impl"
130 // This should be all-zero, pointer-sized.
131 let layout = this.layout_of(this.tcx.types.usize)?;
132 let place = this.allocate(layout, MiriMemoryKind::Machine.into());
133 this.write_scalar(Scalar::from_machine_usize(0, &*this.tcx), place.into())?;
134 Self::add_extern_static(this, "__cxa_thread_atexit_impl", place.ptr);
136 Self::add_extern_static(this, "environ", this.machine.env_vars.environ.unwrap().ptr);
140 // This is some obscure hack that is part of the Windows TLS story. It's a `u8`.
141 let layout = this.layout_of(this.tcx.types.u8)?;
142 let place = this.allocate(layout, MiriMemoryKind::Machine.into());
143 this.write_scalar(Scalar::from_u8(0), place.into())?;
144 Self::add_extern_static(this, "_tls_used", place.ptr);
146 _ => {} // No "extern statics" supported on this target
152 /// The machine itself.
153 pub struct Evaluator<'tcx> {
154 /// Environment variables set by `setenv`.
155 /// Miri does not expose env vars from the host to the emulated program.
156 pub(crate) env_vars: EnvVars<'tcx>,
158 /// Program arguments (`Option` because we can only initialize them after creating the ecx).
159 /// These are *pointers* to argc/argv because macOS.
160 /// We also need the full command line as one string because of Windows.
161 pub(crate) argc: Option<Scalar<Tag>>,
162 pub(crate) argv: Option<Scalar<Tag>>,
163 pub(crate) cmd_line: Option<Scalar<Tag>>,
165 /// Last OS error location in memory. It is a 32-bit integer.
166 pub(crate) last_error: Option<MPlaceTy<'tcx, Tag>>,
169 pub(crate) tls: TlsData<'tcx>,
171 /// If enabled, the `env_vars` field is populated with the host env vars during initialization
172 /// and random number generation is delegated to the host.
173 pub(crate) communicate: bool,
175 /// Whether to enforce the validity invariant.
176 pub(crate) validate: bool,
178 pub(crate) file_handler: FileHandler,
179 pub(crate) dir_handler: DirHandler,
181 /// The temporary used for storing the argument of
182 /// the call to `miri_start_panic` (the panic payload) when unwinding.
183 /// This is pointer-sized, and matches the `Payload` type in `src/libpanic_unwind/miri.rs`.
184 pub(crate) panic_payload: Option<Scalar<Tag>>,
186 /// The "time anchor" for this machine's monotone clock (for `Instant` simulation).
187 pub(crate) time_anchor: Instant,
190 impl<'tcx> Evaluator<'tcx> {
191 pub(crate) fn new(communicate: bool, validate: bool) -> Self {
193 // `env_vars` could be initialized properly here if `Memory` were available before
194 // calling this method.
195 env_vars: EnvVars::default(),
200 tls: TlsData::default(),
203 file_handler: Default::default(),
204 dir_handler: Default::default(),
206 time_anchor: Instant::now(),
211 /// A rustc InterpCx for Miri.
212 pub type MiriEvalContext<'mir, 'tcx> = InterpCx<'mir, 'tcx, Evaluator<'tcx>>;
214 /// A little trait that's useful to be inherited by extension traits.
215 pub trait MiriEvalContextExt<'mir, 'tcx> {
216 fn eval_context_ref<'a>(&'a self) -> &'a MiriEvalContext<'mir, 'tcx>;
217 fn eval_context_mut<'a>(&'a mut self) -> &'a mut MiriEvalContext<'mir, 'tcx>;
219 impl<'mir, 'tcx> MiriEvalContextExt<'mir, 'tcx> for MiriEvalContext<'mir, 'tcx> {
221 fn eval_context_ref(&self) -> &MiriEvalContext<'mir, 'tcx> {
225 fn eval_context_mut(&mut self) -> &mut MiriEvalContext<'mir, 'tcx> {
230 /// Machine hook implementations.
231 impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'tcx> {
232 type MemoryKind = MiriMemoryKind;
234 type FrameExtra = FrameData<'tcx>;
235 type MemoryExtra = MemoryExtra;
236 type AllocExtra = AllocExtra;
237 type PointerTag = Tag;
238 type ExtraFnVal = Dlsym;
241 MonoHashMap<AllocId, (MemoryKind<MiriMemoryKind>, Allocation<Tag, Self::AllocExtra>)>;
243 const GLOBAL_KIND: Option<MiriMemoryKind> = Some(MiriMemoryKind::Global);
245 const CHECK_ALIGN: bool = true;
248 fn enforce_validity(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool {
253 fn find_mir_or_eval_fn(
254 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>,
279 instance: ty::Instance<'tcx>,
280 args: &[OpTy<'tcx, Tag>],
281 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
282 unwind: Option<mir::BasicBlock>,
283 ) -> InterpResult<'tcx> {
284 ecx.call_intrinsic(span, instance, args, ret, unwind)
289 ecx: &mut InterpCx<'mir, 'tcx, Self>,
290 msg: &mir::AssertMessage<'tcx>,
291 unwind: Option<mir::BasicBlock>,
292 ) -> InterpResult<'tcx> {
293 ecx.assert_panic(msg, unwind)
297 fn abort(_ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx, !> {
298 throw_machine_stop!(TerminationInfo::Abort(None))
303 ecx: &rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
305 left: ImmTy<'tcx, Tag>,
306 right: ImmTy<'tcx, Tag>,
307 ) -> InterpResult<'tcx, (Scalar<Tag>, bool, Ty<'tcx>)> {
308 ecx.binary_ptr_op(bin_op, left, right)
312 ecx: &mut InterpCx<'mir, 'tcx, Self>,
313 dest: PlaceTy<'tcx, Tag>,
314 ) -> InterpResult<'tcx> {
315 trace!("box_alloc for {:?}", dest.layout.ty);
316 let layout = ecx.layout_of(dest.layout.ty.builtin_deref(false).unwrap().ty)?;
317 // First argument: `size`.
318 // (`0` is allowed here -- this is expected to be handled by the lang item).
319 let size = Scalar::from_machine_usize(layout.size.bytes(), ecx);
321 // Second argument: `align`.
322 let align = Scalar::from_machine_usize(layout.align.abi.bytes(), ecx);
324 // Call the `exchange_malloc` lang item.
325 let malloc = ecx.tcx.lang_items().exchange_malloc_fn().unwrap();
326 let malloc = ty::Instance::mono(ecx.tcx.tcx, malloc);
329 &[size.into(), align.into()],
331 // Don't do anything when we are done. The `statement()` function will increment
332 // the old stack frame's stmt counter to the next statement, which means that when
333 // `exchange_malloc` returns, we go on evaluating exactly where we want to be.
334 StackPopCleanup::None { cleanup: true },
339 fn canonical_alloc_id(mem: &Memory<'mir, 'tcx, Self>, id: AllocId) -> AllocId {
341 // Figure out if this is an extern static, and if yes, which one.
342 let def_id = match tcx.alloc_map.lock().get(id) {
343 Some(GlobalAlloc::Static(def_id)) if tcx.is_foreign_item(def_id) => def_id,
345 // No need to canonicalize anything.
349 let attrs = tcx.get_attrs(def_id);
350 let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
352 None => tcx.item_name(def_id),
354 // Check if we know this one.
355 if let Some(canonical_id) = mem.extra.extern_statics.get(&link_name) {
356 trace!("canonical_alloc_id: {:?} ({}) -> {:?}", id, link_name, canonical_id);
359 // Return original id; `Memory::get_static_alloc` will throw an error.
364 fn init_allocation_extra<'b>(
365 memory_extra: &MemoryExtra,
367 alloc: Cow<'b, Allocation>,
368 kind: Option<MemoryKind<Self::MemoryKind>>,
369 ) -> (Cow<'b, Allocation<Self::PointerTag, Self::AllocExtra>>, Self::PointerTag) {
370 if Some(id) == memory_extra.tracked_alloc_id {
371 register_diagnostic(NonHaltingDiagnostic::CreatedAlloc(id));
374 let kind = kind.expect("we set our STATIC_KIND so this cannot be None");
375 let alloc = alloc.into_owned();
376 let (stacks, base_tag) =
377 if let Some(stacked_borrows) = memory_extra.stacked_borrows.as_ref() {
378 let (stacks, base_tag) =
379 Stacks::new_allocation(id, alloc.size, Rc::clone(stacked_borrows), kind);
380 (Some(stacks), base_tag)
382 // No stacks, no tag.
383 (None, Tag::Untagged)
385 let mut stacked_borrows = memory_extra.stacked_borrows.as_ref().map(|sb| sb.borrow_mut());
386 let alloc: Allocation<Tag, Self::AllocExtra> = alloc.with_tags_and_extra(
388 if let Some(stacked_borrows) = stacked_borrows.as_mut() {
389 // Only globals may already contain pointers at this point
390 assert_eq!(kind, MiriMemoryKind::Global.into());
391 stacked_borrows.global_base_ptr(alloc)
396 AllocExtra { stacked_borrows: stacks },
398 (Cow::Owned(alloc), base_tag)
402 fn tag_global_base_pointer(memory_extra: &MemoryExtra, id: AllocId) -> Self::PointerTag {
403 if let Some(stacked_borrows) = memory_extra.stacked_borrows.as_ref() {
404 stacked_borrows.borrow_mut().global_base_ptr(id)
412 ecx: &mut InterpCx<'mir, 'tcx, Self>,
413 kind: mir::RetagKind,
414 place: PlaceTy<'tcx, Tag>,
415 ) -> InterpResult<'tcx> {
416 if ecx.memory.extra.stacked_borrows.is_none() {
420 ecx.retag(kind, place)
425 fn stack_push(ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx, FrameData<'tcx>> {
426 let stacked_borrows = ecx.memory.extra.stacked_borrows.as_ref();
427 let call_id = stacked_borrows.map_or(NonZeroU64::new(1).unwrap(), |stacked_borrows| {
428 stacked_borrows.borrow_mut().new_call()
430 Ok(FrameData { call_id, catch_unwind: None })
435 ecx: &mut InterpCx<'mir, 'tcx, Self>,
436 extra: FrameData<'tcx>,
438 ) -> InterpResult<'tcx, StackPopJump> {
439 ecx.handle_stack_pop(extra, unwinding)
444 memory: &Memory<'mir, 'tcx, Self>,
446 ) -> InterpResult<'tcx, Pointer<Self::PointerTag>> {
447 intptrcast::GlobalState::int_to_ptr(int, memory)
452 memory: &Memory<'mir, 'tcx, Self>,
453 ptr: Pointer<Self::PointerTag>,
454 ) -> InterpResult<'tcx, u64> {
455 intptrcast::GlobalState::ptr_to_int(ptr, memory)
459 impl AllocationExtra<Tag> for AllocExtra {
461 fn memory_read<'tcx>(
462 alloc: &Allocation<Tag, AllocExtra>,
465 ) -> InterpResult<'tcx> {
466 if let Some(ref stacked_borrows) = alloc.extra.stacked_borrows {
467 stacked_borrows.memory_read(ptr, size)
474 fn memory_written<'tcx>(
475 alloc: &mut Allocation<Tag, AllocExtra>,
478 ) -> InterpResult<'tcx> {
479 if let Some(ref mut stacked_borrows) = alloc.extra.stacked_borrows {
480 stacked_borrows.memory_written(ptr, size)
487 fn memory_deallocated<'tcx>(
488 alloc: &mut Allocation<Tag, AllocExtra>,
491 ) -> InterpResult<'tcx> {
492 if let Some(ref mut stacked_borrows) = alloc.extra.stacked_borrows {
493 stacked_borrows.memory_deallocated(ptr, size)
500 impl MayLeak for MiriMemoryKind {
502 fn may_leak(self) -> bool {
503 use self::MiriMemoryKind::*;
505 Rust | C | WinHeap | Env => false,
506 Machine | Global => true,