1 use std::cell::RefCell;
3 use std::num::NonZeroU64;
8 use rustc_span::{source_map::DUMMY_SP, Span, SpanData, Symbol};
9 use rustc_target::abi::{Align, Size};
11 use crate::stacked_borrows::{diagnostics::TagHistory, AccessKind};
14 /// Details of premature program termination.
15 pub enum TerminationInfo {
18 UnsupportedInIsolation(String),
22 history: Option<TagHistory>,
24 Int2PtrWithStrictProvenance,
26 MultipleSymbolDefinitions {
39 impl fmt::Display for TerminationInfo {
40 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
41 use TerminationInfo::*;
43 Exit(code) => write!(f, "the evaluated program completed with exit code {code}"),
44 Abort(msg) => write!(f, "{msg}"),
45 UnsupportedInIsolation(msg) => write!(f, "{msg}"),
46 Int2PtrWithStrictProvenance =>
49 "integer-to-pointer casts and `ptr::from_exposed_addr` are not supported with `-Zmiri-strict-provenance`"
51 StackedBorrowsUb { msg, .. } => write!(f, "{msg}"),
52 Deadlock => write!(f, "the evaluated program deadlocked"),
53 MultipleSymbolDefinitions { link_name, .. } =>
54 write!(f, "multiple definitions of symbol `{link_name}`"),
55 SymbolShimClashing { link_name, .. } =>
56 write!(f, "found `{link_name}` symbol definition that clashes with a built-in shim",),
61 impl MachineStopType for TerminationInfo {}
63 /// Miri specific diagnostics
64 pub enum NonHaltingDiagnostic {
65 CreatedPointerTag(NonZeroU64, Option<(AllocId, AllocRange)>),
66 /// This `Item` was popped from the borrow stack, either due to an access with the given tag or
67 /// a deallocation when the second argument is `None`.
68 PoppedPointerTag(Item, Option<(ProvenanceExtra, AccessKind)>),
69 CreatedCallId(CallId),
70 CreatedAlloc(AllocId, Size, Align, MemoryKind<MiriMemoryKind>),
72 RejectedIsolatedOp(String),
77 WeakMemoryOutdatedLoad,
80 /// Level of Miri specific diagnostics
87 /// Attempts to prune a stacktrace to omit the Rust runtime, and returns a bool indicating if any
88 /// frames were pruned. If the stacktrace does not have any local frames, we conclude that it must
89 /// be pointing to a problem in the Rust runtime itself, and do not prune it at all.
90 fn prune_stacktrace<'mir, 'tcx>(
91 ecx: &InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
92 mut stacktrace: Vec<FrameInfo<'tcx>>,
93 ) -> (Vec<FrameInfo<'tcx>>, bool) {
94 match ecx.machine.backtrace_style {
95 BacktraceStyle::Off => {
96 // Remove all frames marked with `caller_location` -- that attribute indicates we
97 // usually want to point at the caller, not them.
98 stacktrace.retain(|frame| !frame.instance.def.requires_caller_location(*ecx.tcx));
99 // Retain one frame so that we can print a span for the error itself
100 stacktrace.truncate(1);
103 BacktraceStyle::Short => {
104 let original_len = stacktrace.len();
105 // Only prune frames if there is at least one local frame. This check ensures that if
106 // we get a backtrace that never makes it to the user code because it has detected a
107 // bug in the Rust runtime, we don't prune away every frame.
108 let has_local_frame = stacktrace.iter().any(|frame| ecx.machine.is_local(frame));
110 // Remove all frames marked with `caller_location` -- that attribute indicates we
111 // usually want to point at the caller, not them.
112 stacktrace.retain(|frame| !frame.instance.def.requires_caller_location(*ecx.tcx));
114 // This is part of the logic that `std` uses to select the relevant part of a
115 // backtrace. But here, we only look for __rust_begin_short_backtrace, not
116 // __rust_end_short_backtrace because the end symbol comes from a call to the default
118 stacktrace = stacktrace
120 .take_while(|frame| {
121 let def_id = frame.instance.def_id();
122 let path = ecx.tcx.tcx.def_path_str(def_id);
123 !path.contains("__rust_begin_short_backtrace")
125 .collect::<Vec<_>>();
127 // After we prune frames from the bottom, there are a few left that are part of the
128 // Rust runtime. So we remove frames until we get to a local symbol, which should be
130 // This len check ensures that we don't somehow remove every frame, as doing so breaks
131 // the primary error message.
132 while stacktrace.len() > 1
133 && stacktrace.last().map_or(false, |frame| !ecx.machine.is_local(frame))
138 let was_pruned = stacktrace.len() != original_len;
139 (stacktrace, was_pruned)
141 BacktraceStyle::Full => (stacktrace, false),
145 /// Emit a custom diagnostic without going through the miri-engine machinery
146 pub fn report_error<'tcx, 'mir>(
147 ecx: &InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
148 e: InterpErrorInfo<'tcx>,
152 let mut msg = vec![];
154 let (title, helps) = match &e.kind() {
155 MachineStop(info) => {
156 let info = info.downcast_ref::<TerminationInfo>().expect("invalid MachineStop payload");
157 use TerminationInfo::*;
158 let title = match info {
159 Exit(code) => return Some(*code),
160 Abort(_) => Some("abnormal termination"),
161 UnsupportedInIsolation(_) | Int2PtrWithStrictProvenance =>
162 Some("unsupported operation"),
163 StackedBorrowsUb { .. } => Some("Undefined Behavior"),
164 Deadlock => Some("deadlock"),
165 MultipleSymbolDefinitions { .. } | SymbolShimClashing { .. } => None,
168 let helps = match info {
169 UnsupportedInIsolation(_) =>
171 (None, format!("pass the flag `-Zmiri-disable-isolation` to disable isolation;")),
172 (None, format!("or pass `-Zmiri-isolation-error=warn` to configure Miri to return an error code from isolated operations (if supported for that operation) and continue with a warning")),
174 StackedBorrowsUb { help, history, .. } => {
175 let url = "https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md";
176 msg.extend(help.clone());
177 let mut helps = vec![
178 (None, format!("this indicates a potential bug in the program: it performed an invalid operation, but the Stacked Borrows rules it violated are still experimental")),
179 (None, format!("see {url} for further information")),
182 Some(TagHistory::Tagged {tag, created: (created_range, created_span), invalidated, protected }) => {
183 let msg = format!("{tag:?} was created by a retag at offsets {created_range:?}");
184 helps.push((Some(*created_span), msg));
185 if let Some((invalidated_range, invalidated_span)) = invalidated {
186 let msg = format!("{tag:?} was later invalidated at offsets {invalidated_range:?}");
187 helps.push((Some(*invalidated_span), msg));
189 if let Some((protecting_tag, protecting_tag_span, protection_span)) = protected {
190 helps.push((Some(*protecting_tag_span), format!("{tag:?} was protected due to {protecting_tag:?} which was created here")));
191 helps.push((Some(*protection_span), format!("this protector is live for this call")));
198 MultipleSymbolDefinitions { first, first_crate, second, second_crate, .. } =>
200 (Some(*first), format!("it's first defined here, in crate `{first_crate}`")),
201 (Some(*second), format!("then it's defined here again, in crate `{second_crate}`")),
203 SymbolShimClashing { link_name, span } =>
204 vec![(Some(*span), format!("the `{link_name}` symbol is defined here"))],
205 Int2PtrWithStrictProvenance =>
206 vec![(None, format!("use Strict Provenance APIs (https://doc.rust-lang.org/nightly/std/ptr/index.html#strict-provenance, https://crates.io/crates/sptr) instead"))],
213 let title = match e.kind() {
215 "unsupported operation",
216 UndefinedBehavior(_) =>
217 "Undefined Behavior",
218 ResourceExhaustion(_) =>
219 "resource exhaustion",
221 InvalidProgramInfo::AlreadyReported(_) |
222 InvalidProgramInfo::Layout(..) |
223 InvalidProgramInfo::ReferencedConstant
225 "post-monomorphization error",
227 bug!("This error should be impossible in Miri: {kind:?}"),
230 let helps = match e.kind() {
232 UnsupportedOpInfo::ThreadLocalStatic(_) |
233 UnsupportedOpInfo::ReadExternStatic(_)
235 panic!("Error should never be raised by Miri: {kind:?}", kind = e.kind()),
237 UnsupportedOpInfo::Unsupported(_) |
238 UnsupportedOpInfo::PartialPointerOverwrite(_) |
239 UnsupportedOpInfo::ReadPointerAsBytes
241 vec![(None, format!("this is likely not a bug in the program; it indicates that the program performed an operation that the interpreter does not support"))],
242 UndefinedBehavior(UndefinedBehaviorInfo::AlignmentCheckFailed { .. })
243 if ecx.machine.check_alignment == AlignmentCheck::Symbolic
246 (None, format!("this usually indicates that your program performed an invalid operation and caused Undefined Behavior")),
247 (None, format!("but due to `-Zmiri-symbolic-alignment-check`, alignment errors can also be false positives")),
249 UndefinedBehavior(_) =>
251 (None, format!("this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior")),
252 (None, format!("see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information")),
254 InvalidProgram(_) | ResourceExhaustion(_) | MachineStop(_) =>
261 let stacktrace = ecx.generate_stacktrace();
262 let (stacktrace, was_pruned) = prune_stacktrace(ecx, stacktrace);
264 msg.insert(0, e.to_string());
268 &if let Some(title) = title { format!("{}: {}", title, msg[0]) } else { msg[0].clone() },
274 // Include a note like `std` does when we omit frames from a backtrace
276 ecx.tcx.sess.diagnostic().note_without_error(
277 "some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace",
281 // Debug-dump all locals.
282 for (i, frame) in ecx.active_thread_stack().iter().enumerate() {
283 trace!("-------------------");
284 trace!("Frame {}", i);
285 trace!(" return: {:?}", *frame.return_place);
286 for (i, local) in frame.locals.iter().enumerate() {
287 trace!(" local {}: {:?}", i, local.value);
291 // Extra output to help debug specific issues.
293 UndefinedBehavior(UndefinedBehaviorInfo::InvalidUninitBytes(Some((alloc_id, access)))) => {
295 "Uninitialized memory occurred at {alloc_id:?}{range:?}, in this allocation:",
296 range = access.uninit,
298 eprintln!("{:?}", ecx.dump_alloc(*alloc_id));
306 /// Report an error or note (depending on the `error` argument) with the given stacktrace.
307 /// Also emits a full stacktrace of the interpreter stack.
308 /// We want to present a multi-line span message for some errors. Diagnostics do not support this
309 /// directly, so we pass the lines as a `Vec<String>` and display each line after the first with an
310 /// additional `span_label` or `note` call.
311 fn report_msg<'mir, 'tcx>(
312 ecx: &InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
313 diag_level: DiagLevel,
315 span_msg: Vec<String>,
316 helps: Vec<(Option<SpanData>, String)>,
317 stacktrace: &[FrameInfo<'tcx>],
319 let span = stacktrace.first().map_or(DUMMY_SP, |fi| fi.span);
320 let sess = ecx.tcx.sess;
321 let mut err = match diag_level {
322 DiagLevel::Error => sess.struct_span_err(span, title).forget_guarantee(),
323 DiagLevel::Warning => sess.struct_span_warn(span, title),
324 DiagLevel::Note => sess.diagnostic().span_note_diag(span, title),
327 // Show main message.
328 if span != DUMMY_SP {
329 for line in span_msg {
330 err.span_label(span, line);
333 // Make sure we show the message even when it is a dummy span.
334 for line in span_msg {
337 err.note("(no span available)");
340 // Show help messages.
341 if !helps.is_empty() {
342 for (span_data, help) in helps {
343 if let Some(span_data) = span_data {
344 err.span_help(span_data.span(), &help);
349 // Add visual separator before backtrace.
350 err.note("backtrace:");
353 for (idx, frame_info) in stacktrace.iter().enumerate() {
354 let is_local = ecx.machine.is_local(frame_info);
355 // No span for non-local frames and the first frame (which is the error site).
356 if is_local && idx > 0 {
357 err.span_note(frame_info.span, &frame_info.to_string());
359 err.note(&frame_info.to_string());
367 static DIAGNOSTICS: RefCell<Vec<NonHaltingDiagnostic>> = RefCell::new(Vec::new());
370 /// Schedule a diagnostic for emitting. This function works even if you have no `InterpCx` available.
371 /// The diagnostic will be emitted after the current interpreter step is finished.
372 pub fn register_diagnostic(e: NonHaltingDiagnostic) {
373 DIAGNOSTICS.with(|diagnostics| diagnostics.borrow_mut().push(e));
376 /// Remember enough about the topmost frame so that we can restore the stack
377 /// after a step was taken.
378 pub struct TopFrameInfo<'tcx> {
380 instance: Option<ty::Instance<'tcx>>,
384 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
385 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
386 fn preprocess_diagnostics(&self) -> TopFrameInfo<'tcx> {
387 // Ensure we have no lingering diagnostics.
388 DIAGNOSTICS.with(|diagnostics| assert!(diagnostics.borrow().is_empty()));
390 let this = self.eval_context_ref();
391 if this.active_thread_stack().is_empty() {
392 // Diagnostics can happen even with the empty stack (e.g. deallocation of thread-local statics).
393 return TopFrameInfo { stack_size: 0, instance: None, span: DUMMY_SP };
395 let frame = this.frame();
398 stack_size: this.active_thread_stack().len(),
399 instance: Some(frame.instance),
400 span: frame.current_span(),
404 /// Emit all diagnostics that were registed with `register_diagnostics`
405 fn process_diagnostics(&self, info: TopFrameInfo<'tcx>) {
406 let this = self.eval_context_ref();
407 DIAGNOSTICS.with(|diagnostics| {
408 let mut diagnostics = diagnostics.borrow_mut();
409 if diagnostics.is_empty() {
412 // We need to fix up the stack trace, because the machine has already
413 // stepped to the next statement.
414 let mut stacktrace = this.generate_stacktrace();
415 // Remove newly pushed frames.
416 while stacktrace.len() > info.stack_size {
417 stacktrace.remove(0);
419 // Add popped frame back.
420 if stacktrace.len() < info.stack_size {
422 stacktrace.len() == info.stack_size - 1,
423 "we should never pop more than one frame at once"
425 let frame_info = FrameInfo {
426 instance: info.instance.unwrap(),
430 stacktrace.insert(0, frame_info);
431 } else if let Some(instance) = info.instance {
432 // Adjust topmost frame.
433 stacktrace[0].span = info.span;
435 stacktrace[0].instance, instance,
436 "we should not pop and push a frame in one step"
440 let (stacktrace, _was_pruned) = prune_stacktrace(this, stacktrace);
443 for e in diagnostics.drain(..) {
444 use NonHaltingDiagnostic::*;
446 CreatedPointerTag(tag, None) =>
447 format!("created tag {tag:?}"),
448 CreatedPointerTag(tag, Some((alloc_id, range))) =>
449 format!("created tag {tag:?} at {alloc_id:?}{range:?}"),
450 PoppedPointerTag(item, tag) =>
454 "popped tracked tag for item {item:?} due to deallocation",
456 Some((tag, access)) => {
458 "popped tracked tag for item {item:?} due to {access:?} access for {tag:?}",
463 format!("function call with id {id}"),
464 CreatedAlloc(AllocId(id), size, align, kind) =>
466 "created {kind} allocation of {size} bytes (alignment {align} bytes) with id {id}",
468 align = align.bytes(),
470 FreedAlloc(AllocId(id)) =>
471 format!("freed allocation with id {id}"),
472 RejectedIsolatedOp(ref op) =>
473 format!("{op} was made to return an error due to isolation"),
475 format!("progress report: current operation being executed is here"),
477 format!("integer-to-pointer cast"),
478 WeakMemoryOutdatedLoad =>
479 format!("weak memory emulation: outdated value returned from load"),
482 let (title, diag_level) = match e {
483 RejectedIsolatedOp(_) =>
484 ("operation rejected by isolation", DiagLevel::Warning),
485 Int2Ptr { .. } => ("integer-to-pointer cast", DiagLevel::Warning),
486 CreatedPointerTag(..)
487 | PoppedPointerTag(..)
492 | WeakMemoryOutdatedLoad =>
493 ("tracking was triggered", DiagLevel::Note),
496 let helps = match e {
497 Int2Ptr { details: true } =>
499 (None, format!("This program is using integer-to-pointer casts or (equivalently) `ptr::from_exposed_addr`,")),
500 (None, format!("which means that Miri might miss pointer bugs in this program.")),
501 (None, format!("See https://doc.rust-lang.org/nightly/std/ptr/fn.from_exposed_addr.html for more details on that operation.")),
502 (None, format!("To ensure that Miri does not miss bugs in your program, use Strict Provenance APIs (https://doc.rust-lang.org/nightly/std/ptr/index.html#strict-provenance, https://crates.io/crates/sptr) instead.")),
503 (None, format!("You can then pass the `-Zmiri-strict-provenance` flag to Miri, to ensure you are not relying on `from_exposed_addr` semantics.")),
504 (None, format!("Alternatively, the `-Zmiri-permissive-provenance` flag disables this warning.")),
509 report_msg(this, diag_level, title, vec![msg], helps, &stacktrace);
514 /// We had a panic in Miri itself, try to print something useful.
515 fn handle_ice(&self) {
518 "Miri caused an ICE during evaluation. Here's the interpreter backtrace at the time of the panic:"
520 let this = self.eval_context_ref();
521 let stacktrace = this.generate_stacktrace();
525 "the place in the program where the ICE was triggered",