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;
14 use rustc_data_structures::fx::FxHashMap;
15 use rustc_middle::{mir, ty};
16 use rustc_target::abi::{LayoutOf, Size};
18 use rustc_span::symbol::{sym, Symbol};
22 // Some global facts about the emulated machine.
23 pub const PAGE_SIZE: u64 = 4 * 1024; // FIXME: adjust to target architecture
24 pub const STACK_ADDR: u64 = 32 * PAGE_SIZE; // not really about the "stack", but where we start assigning integer addresses to allocations
25 pub const STACK_SIZE: u64 = 16 * PAGE_SIZE; // whatever
26 pub const NUM_CPUS: u64 = 1;
28 /// Extra data stored with each stack frame
30 pub struct FrameData<'tcx> {
31 /// Extra data for Stacked Borrows.
32 pub call_id: stacked_borrows::CallId,
34 /// If this is Some(), then this is a special "catch unwind" frame (the frame of `try_fn`
35 /// called by `try`). When this frame is popped during unwinding a panic,
36 /// we stop unwinding, use the `CatchUnwindData` to handle catching.
37 pub catch_unwind: Option<CatchUnwindData<'tcx>>,
40 /// Extra memory kinds
41 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
42 pub enum MiriMemoryKind {
43 /// `__rust_alloc` memory.
47 /// Windows `HeapAlloc` memory.
49 /// Memory for args, errno, extern statics and other parts of the machine-managed environment.
50 /// This memory may leak.
52 /// Memory for env vars. Separate from `Machine` because we clean it up and leak-check it.
54 /// Globals copied from `tcx`.
55 /// This memory may leak.
59 impl Into<MemoryKind<MiriMemoryKind>> for MiriMemoryKind {
61 fn into(self) -> MemoryKind<MiriMemoryKind> {
62 MemoryKind::Machine(self)
66 impl MayLeak for MiriMemoryKind {
68 fn may_leak(self) -> bool {
69 use self::MiriMemoryKind::*;
71 Rust | C | WinHeap | Env => false,
72 Machine | Global => true,
77 impl fmt::Display for MiriMemoryKind {
78 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
79 use self::MiriMemoryKind::*;
81 Rust => write!(f, "Rust heap"),
82 C => write!(f, "C heap"),
83 WinHeap => write!(f, "Windows heap"),
84 Machine => write!(f, "machine-managed memory"),
85 Env => write!(f, "environment variable"),
86 Global => write!(f, "global"),
91 /// Extra per-allocation data
92 #[derive(Debug, Clone)]
93 pub struct AllocExtra {
94 /// Stacked Borrows state is only added if it is enabled.
95 pub stacked_borrows: Option<stacked_borrows::AllocExtra>,
98 /// Extra global memory data
99 #[derive(Clone, Debug)]
100 pub struct MemoryExtra {
101 pub stacked_borrows: Option<stacked_borrows::MemoryExtra>,
102 pub intptrcast: intptrcast::MemoryExtra,
104 /// Mapping extern static names to their canonical allocation.
105 extern_statics: FxHashMap<Symbol, AllocId>,
107 /// The random number generator used for resolving non-determinism.
108 /// Needs to be queried by ptr_to_int, hence needs interior mutability.
109 pub(crate) rng: RefCell<StdRng>,
111 /// An allocation ID to report when it is being allocated
112 /// (helps for debugging memory leaks).
113 tracked_alloc_id: Option<AllocId>,
117 pub fn new(rng: StdRng, stacked_borrows: bool, tracked_pointer_tag: Option<PtrId>, tracked_alloc_id: Option<AllocId>) -> Self {
118 let stacked_borrows = if stacked_borrows {
119 Some(Rc::new(RefCell::new(stacked_borrows::GlobalState::new(tracked_pointer_tag))))
125 intptrcast: Default::default(),
126 extern_statics: FxHashMap::default(),
127 rng: RefCell::new(rng),
132 fn add_extern_static<'tcx, 'mir>(
133 this: &mut MiriEvalContext<'mir, 'tcx>,
137 let ptr = ptr.assert_ptr();
138 assert_eq!(ptr.offset, Size::ZERO);
142 .insert(Symbol::intern(name), ptr.alloc_id)
146 /// Sets up the "extern statics" for this machine.
147 pub fn init_extern_statics<'tcx, 'mir>(
148 this: &mut MiriEvalContext<'mir, 'tcx>,
149 ) -> InterpResult<'tcx> {
150 match this.tcx.sess.target.target.target_os.as_str() {
152 // "__cxa_thread_atexit_impl"
153 // This should be all-zero, pointer-sized.
154 let layout = this.layout_of(this.tcx.types.usize)?;
155 let place = this.allocate(layout, MiriMemoryKind::Machine.into());
156 this.write_scalar(Scalar::from_machine_usize(0, this), place.into())?;
157 Self::add_extern_static(this, "__cxa_thread_atexit_impl", place.ptr);
159 Self::add_extern_static(this, "environ", this.machine.env_vars.environ.unwrap().ptr);
163 // This is some obscure hack that is part of the Windows TLS story. It's a `u8`.
164 let layout = this.layout_of(this.tcx.types.u8)?;
165 let place = this.allocate(layout, MiriMemoryKind::Machine.into());
166 this.write_scalar(Scalar::from_u8(0), place.into())?;
167 Self::add_extern_static(this, "_tls_used", place.ptr);
169 _ => {} // No "extern statics" supported on this target
175 /// The machine itself.
176 pub struct Evaluator<'tcx> {
177 /// Environment variables set by `setenv`.
178 /// Miri does not expose env vars from the host to the emulated program.
179 pub(crate) env_vars: EnvVars<'tcx>,
181 /// Program arguments (`Option` because we can only initialize them after creating the ecx).
182 /// These are *pointers* to argc/argv because macOS.
183 /// We also need the full command line as one string because of Windows.
184 pub(crate) argc: Option<Scalar<Tag>>,
185 pub(crate) argv: Option<Scalar<Tag>>,
186 pub(crate) cmd_line: Option<Scalar<Tag>>,
188 /// Last OS error location in memory. It is a 32-bit integer.
189 pub(crate) last_error: Option<MPlaceTy<'tcx, Tag>>,
192 pub(crate) tls: TlsData<'tcx>,
194 /// If enabled, the `env_vars` field is populated with the host env vars during initialization
195 /// and random number generation is delegated to the host.
196 pub(crate) communicate: bool,
198 /// Whether to enforce the validity invariant.
199 pub(crate) validate: bool,
201 pub(crate) file_handler: FileHandler,
202 pub(crate) dir_handler: DirHandler,
204 /// The temporary used for storing the argument of
205 /// the call to `miri_start_panic` (the panic payload) when unwinding.
206 /// This is pointer-sized, and matches the `Payload` type in `src/libpanic_unwind/miri.rs`.
207 pub(crate) panic_payload: Option<Scalar<Tag>>,
209 /// The "time anchor" for this machine's monotone clock (for `Instant` simulation).
210 pub(crate) time_anchor: Instant,
213 impl<'tcx> Evaluator<'tcx> {
214 pub(crate) fn new(communicate: bool, validate: bool) -> Self {
216 // `env_vars` could be initialized properly here if `Memory` were available before
217 // calling this method.
218 env_vars: EnvVars::default(),
223 tls: TlsData::default(),
226 file_handler: Default::default(),
227 dir_handler: Default::default(),
229 time_anchor: Instant::now(),
234 /// A rustc InterpCx for Miri.
235 pub type MiriEvalContext<'mir, 'tcx> = InterpCx<'mir, 'tcx, Evaluator<'tcx>>;
237 /// A little trait that's useful to be inherited by extension traits.
238 pub trait MiriEvalContextExt<'mir, 'tcx> {
239 fn eval_context_ref<'a>(&'a self) -> &'a MiriEvalContext<'mir, 'tcx>;
240 fn eval_context_mut<'a>(&'a mut self) -> &'a mut MiriEvalContext<'mir, 'tcx>;
242 impl<'mir, 'tcx> MiriEvalContextExt<'mir, 'tcx> for MiriEvalContext<'mir, 'tcx> {
244 fn eval_context_ref(&self) -> &MiriEvalContext<'mir, 'tcx> {
248 fn eval_context_mut(&mut self) -> &mut MiriEvalContext<'mir, 'tcx> {
253 /// Machine hook implementations.
254 impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'tcx> {
255 type MemoryKind = MiriMemoryKind;
257 type FrameExtra = FrameData<'tcx>;
258 type MemoryExtra = MemoryExtra;
259 type AllocExtra = AllocExtra;
260 type PointerTag = Tag;
261 type ExtraFnVal = Dlsym;
264 MonoHashMap<AllocId, (MemoryKind<MiriMemoryKind>, Allocation<Tag, Self::AllocExtra>)>;
266 const GLOBAL_KIND: Option<MiriMemoryKind> = Some(MiriMemoryKind::Global);
268 const CHECK_ALIGN: bool = true;
271 fn enforce_validity(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool {
276 fn find_mir_or_eval_fn(
277 ecx: &mut 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, Option<&'mir mir::Body<'tcx>>> {
283 ecx.find_mir_or_eval_fn(instance, args, ret, unwind)
288 ecx: &mut InterpCx<'mir, 'tcx, Self>,
290 args: &[OpTy<'tcx, Tag>],
291 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
292 _unwind: Option<mir::BasicBlock>,
293 ) -> InterpResult<'tcx> {
294 ecx.call_dlsym(fn_val, args, ret)
299 ecx: &mut rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
300 instance: ty::Instance<'tcx>,
301 args: &[OpTy<'tcx, Tag>],
302 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
303 unwind: Option<mir::BasicBlock>,
304 ) -> InterpResult<'tcx> {
305 ecx.call_intrinsic(instance, args, ret, unwind)
310 ecx: &mut InterpCx<'mir, 'tcx, Self>,
311 msg: &mir::AssertMessage<'tcx>,
312 unwind: Option<mir::BasicBlock>,
313 ) -> InterpResult<'tcx> {
314 ecx.assert_panic(msg, unwind)
318 fn abort(_ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx, !> {
319 throw_machine_stop!(TerminationInfo::Abort(None))
324 ecx: &rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
326 left: ImmTy<'tcx, Tag>,
327 right: ImmTy<'tcx, Tag>,
328 ) -> InterpResult<'tcx, (Scalar<Tag>, bool, ty::Ty<'tcx>)> {
329 ecx.binary_ptr_op(bin_op, left, right)
333 ecx: &mut InterpCx<'mir, 'tcx, Self>,
334 dest: PlaceTy<'tcx, Tag>,
335 ) -> InterpResult<'tcx> {
336 trace!("box_alloc for {:?}", dest.layout.ty);
337 let layout = ecx.layout_of(dest.layout.ty.builtin_deref(false).unwrap().ty)?;
338 // First argument: `size`.
339 // (`0` is allowed here -- this is expected to be handled by the lang item).
340 let size = Scalar::from_machine_usize(layout.size.bytes(), ecx);
342 // Second argument: `align`.
343 let align = Scalar::from_machine_usize(layout.align.abi.bytes(), ecx);
345 // Call the `exchange_malloc` lang item.
346 let malloc = ecx.tcx.lang_items().exchange_malloc_fn().unwrap();
347 let malloc = ty::Instance::mono(ecx.tcx.tcx, malloc);
350 &[size.into(), align.into()],
352 // Don't do anything when we are done. The `statement()` function will increment
353 // the old stack frame's stmt counter to the next statement, which means that when
354 // `exchange_malloc` returns, we go on evaluating exactly where we want to be.
355 StackPopCleanup::None { cleanup: true },
360 fn canonical_alloc_id(mem: &Memory<'mir, 'tcx, Self>, id: AllocId) -> AllocId {
362 // Figure out if this is an extern static, and if yes, which one.
363 let def_id = match tcx.alloc_map.lock().get(id) {
364 Some(GlobalAlloc::Static(def_id)) if tcx.is_foreign_item(def_id) => def_id,
366 // No need to canonicalize anything.
370 let attrs = tcx.get_attrs(def_id);
371 let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
373 None => tcx.item_name(def_id),
375 // Check if we know this one.
376 if let Some(canonical_id) = mem.extra.extern_statics.get(&link_name) {
377 trace!("canonical_alloc_id: {:?} ({}) -> {:?}", id, link_name, canonical_id);
380 // Return original id; `Memory::get_static_alloc` will throw an error.
385 fn init_allocation_extra<'b>(
386 memory_extra: &MemoryExtra,
388 alloc: Cow<'b, Allocation>,
389 kind: Option<MemoryKind<Self::MemoryKind>>,
390 ) -> (Cow<'b, Allocation<Self::PointerTag, Self::AllocExtra>>, Self::PointerTag) {
391 if Some(id) == memory_extra.tracked_alloc_id {
392 register_diagnostic(NonHaltingDiagnostic::CreatedAlloc(id));
395 let kind = kind.expect("we set our STATIC_KIND so this cannot be None");
396 let alloc = alloc.into_owned();
397 let (stacks, base_tag) =
398 if let Some(stacked_borrows) = memory_extra.stacked_borrows.as_ref() {
399 let (stacks, base_tag) =
400 Stacks::new_allocation(id, alloc.size, Rc::clone(stacked_borrows), kind);
401 (Some(stacks), base_tag)
403 // No stacks, no tag.
404 (None, Tag::Untagged)
406 let mut stacked_borrows = memory_extra.stacked_borrows.as_ref().map(|sb| sb.borrow_mut());
407 let alloc: Allocation<Tag, Self::AllocExtra> = alloc.with_tags_and_extra(
409 if let Some(stacked_borrows) = stacked_borrows.as_mut() {
410 // Only globals may already contain pointers at this point
411 assert_eq!(kind, MiriMemoryKind::Global.into());
412 stacked_borrows.global_base_ptr(alloc)
417 AllocExtra { stacked_borrows: stacks },
419 (Cow::Owned(alloc), base_tag)
423 fn tag_global_base_pointer(memory_extra: &MemoryExtra, id: AllocId) -> Self::PointerTag {
424 if let Some(stacked_borrows) = memory_extra.stacked_borrows.as_ref() {
425 stacked_borrows.borrow_mut().global_base_ptr(id)
433 ecx: &mut InterpCx<'mir, 'tcx, Self>,
434 kind: mir::RetagKind,
435 place: PlaceTy<'tcx, Tag>,
436 ) -> InterpResult<'tcx> {
437 if ecx.memory.extra.stacked_borrows.is_none() {
441 ecx.retag(kind, place)
446 fn stack_push(ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx, FrameData<'tcx>> {
447 let stacked_borrows = ecx.memory.extra.stacked_borrows.as_ref();
448 let call_id = stacked_borrows.map_or(NonZeroU64::new(1).unwrap(), |stacked_borrows| {
449 stacked_borrows.borrow_mut().new_call()
451 Ok(FrameData { call_id, catch_unwind: None })
456 ecx: &mut InterpCx<'mir, 'tcx, Self>,
457 extra: FrameData<'tcx>,
459 ) -> InterpResult<'tcx, StackPopJump> {
460 ecx.handle_stack_pop(extra, unwinding)
465 memory: &Memory<'mir, 'tcx, Self>,
467 ) -> InterpResult<'tcx, Pointer<Self::PointerTag>> {
468 intptrcast::GlobalState::int_to_ptr(int, memory)
473 memory: &Memory<'mir, 'tcx, Self>,
474 ptr: Pointer<Self::PointerTag>,
475 ) -> InterpResult<'tcx, u64> {
476 intptrcast::GlobalState::ptr_to_int(ptr, memory)
480 impl AllocationExtra<Tag> for AllocExtra {
482 fn memory_read<'tcx>(
483 alloc: &Allocation<Tag, AllocExtra>,
486 ) -> InterpResult<'tcx> {
487 if let Some(ref stacked_borrows) = alloc.extra.stacked_borrows {
488 stacked_borrows.memory_read(ptr, size)
495 fn memory_written<'tcx>(
496 alloc: &mut Allocation<Tag, AllocExtra>,
499 ) -> InterpResult<'tcx> {
500 if let Some(ref mut stacked_borrows) = alloc.extra.stacked_borrows {
501 stacked_borrows.memory_written(ptr, size)
508 fn memory_deallocated<'tcx>(
509 alloc: &mut Allocation<Tag, AllocExtra>,
512 ) -> InterpResult<'tcx> {
513 if let Some(ref mut stacked_borrows) = alloc.extra.stacked_borrows {
514 stacked_borrows.memory_deallocated(ptr, size)