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::helpers::HexRange;
12 use crate::stacked_borrows::{diagnostics::TagHistory, AccessKind};
15 /// Details of premature program termination.
16 pub enum TerminationInfo {
19 UnsupportedInIsolation(String),
23 history: Option<TagHistory>,
25 Int2PtrWithStrictProvenance,
27 MultipleSymbolDefinitions {
40 impl fmt::Display for TerminationInfo {
41 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
42 use TerminationInfo::*;
44 Exit(code) => write!(f, "the evaluated program completed with exit code {}", code),
45 Abort(msg) => write!(f, "{}", msg),
46 UnsupportedInIsolation(msg) => write!(f, "{}", msg),
47 Int2PtrWithStrictProvenance =>
50 "integer-to-pointer casts and `ptr::from_exposed_addr` are not supported with `-Zmiri-strict-provenance`"
52 StackedBorrowsUb { msg, .. } => write!(f, "{}", msg),
53 Deadlock => write!(f, "the evaluated program deadlocked"),
54 MultipleSymbolDefinitions { link_name, .. } =>
55 write!(f, "multiple definitions of symbol `{}`", link_name),
56 SymbolShimClashing { link_name, .. } =>
59 "found `{}` symbol definition that clashes with a built-in shim",
66 impl MachineStopType for TerminationInfo {}
68 /// Miri specific diagnostics
69 pub enum NonHaltingDiagnostic {
70 CreatedPointerTag(NonZeroU64),
71 /// This `Item` was popped from the borrow stack, either due to an access with the given tag or
72 /// a deallocation when the second argument is `None`.
73 PoppedPointerTag(Item, Option<(SbTagExtra, AccessKind)>),
74 CreatedCallId(CallId),
75 CreatedAlloc(AllocId, Size, Align, MemoryKind<MiriMemoryKind>),
77 RejectedIsolatedOp(String),
84 /// Level of Miri specific diagnostics
91 /// Attempts to prune a stacktrace to omit the Rust runtime, and returns a bool indicating if any
92 /// frames were pruned. If the stacktrace does not have any local frames, we conclude that it must
93 /// be pointing to a problem in the Rust runtime itself, and do not prune it at all.
94 fn prune_stacktrace<'mir, 'tcx>(
95 ecx: &InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
96 mut stacktrace: Vec<FrameInfo<'tcx>>,
97 ) -> (Vec<FrameInfo<'tcx>>, bool) {
98 match ecx.machine.backtrace_style {
99 BacktraceStyle::Off => {
100 // Remove all frames marked with `caller_location` -- that attribute indicates we
101 // usually want to point at the caller, not them.
102 stacktrace.retain(|frame| !frame.instance.def.requires_caller_location(*ecx.tcx));
103 // Retain one frame so that we can print a span for the error itself
104 stacktrace.truncate(1);
107 BacktraceStyle::Short => {
108 let original_len = stacktrace.len();
109 // Only prune frames if there is at least one local frame. This check ensures that if
110 // we get a backtrace that never makes it to the user code because it has detected a
111 // bug in the Rust runtime, we don't prune away every frame.
112 let has_local_frame = stacktrace.iter().any(|frame| ecx.machine.is_local(frame));
114 // Remove all frames marked with `caller_location` -- that attribute indicates we
115 // usually want to point at the caller, not them.
116 stacktrace.retain(|frame| !frame.instance.def.requires_caller_location(*ecx.tcx));
118 // This is part of the logic that `std` uses to select the relevant part of a
119 // backtrace. But here, we only look for __rust_begin_short_backtrace, not
120 // __rust_end_short_backtrace because the end symbol comes from a call to the default
122 stacktrace = stacktrace
124 .take_while(|frame| {
125 let def_id = frame.instance.def_id();
126 let path = ecx.tcx.tcx.def_path_str(def_id);
127 !path.contains("__rust_begin_short_backtrace")
129 .collect::<Vec<_>>();
131 // After we prune frames from the bottom, there are a few left that are part of the
132 // Rust runtime. So we remove frames until we get to a local symbol, which should be
134 // This len check ensures that we don't somehow remove every frame, as doing so breaks
135 // the primary error message.
136 while stacktrace.len() > 1
137 && stacktrace.last().map_or(false, |frame| !ecx.machine.is_local(frame))
142 let was_pruned = stacktrace.len() != original_len;
143 (stacktrace, was_pruned)
145 BacktraceStyle::Full => (stacktrace, false),
149 /// Emit a custom diagnostic without going through the miri-engine machinery
150 pub fn report_error<'tcx, 'mir>(
151 ecx: &InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
152 e: InterpErrorInfo<'tcx>,
156 let mut msg = vec![];
158 let (title, helps) = match &e.kind() {
159 MachineStop(info) => {
160 let info = info.downcast_ref::<TerminationInfo>().expect("invalid MachineStop payload");
161 use TerminationInfo::*;
162 let title = match info {
163 Exit(code) => return Some(*code),
164 Abort(_) => Some("abnormal termination"),
165 UnsupportedInIsolation(_) | Int2PtrWithStrictProvenance =>
166 Some("unsupported operation"),
167 StackedBorrowsUb { .. } => Some("Undefined Behavior"),
168 Deadlock => Some("deadlock"),
169 MultipleSymbolDefinitions { .. } | SymbolShimClashing { .. } => None,
172 let helps = match info {
173 UnsupportedInIsolation(_) =>
175 (None, format!("pass the flag `-Zmiri-disable-isolation` to disable isolation;")),
176 (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")),
178 StackedBorrowsUb { help, history, .. } => {
179 let url = "https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md";
180 msg.extend(help.clone());
181 let mut helps = vec![
182 (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")),
183 (None, format!("see {url} for further information")),
186 Some(TagHistory::Tagged {tag, created: (created_range, created_span), invalidated, protected }) => {
187 let msg = format!("{:?} was created by a retag at offsets {}", tag, HexRange(*created_range));
188 helps.push((Some(*created_span), msg));
189 if let Some((invalidated_range, invalidated_span)) = invalidated {
190 let msg = format!("{:?} was later invalidated at offsets {}", tag, HexRange(*invalidated_range));
191 helps.push((Some(*invalidated_span), msg));
193 if let Some((protecting_tag, protecting_tag_span, protection_span)) = protected {
194 helps.push((Some(*protecting_tag_span), format!("{:?} was protected due to {:?} which was created here", tag, protecting_tag)));
195 helps.push((Some(*protection_span), format!("this protector is live for this call")));
202 MultipleSymbolDefinitions { first, first_crate, second, second_crate, .. } =>
204 (Some(*first), format!("it's first defined here, in crate `{}`", first_crate)),
205 (Some(*second), format!("then it's defined here again, in crate `{}`", second_crate)),
207 SymbolShimClashing { link_name, span } =>
208 vec![(Some(*span), format!("the `{}` symbol is defined here", link_name))],
209 Int2PtrWithStrictProvenance =>
210 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"))],
217 let title = match e.kind() {
219 "unsupported operation",
220 UndefinedBehavior(_) =>
221 "Undefined Behavior",
222 ResourceExhaustion(_) =>
223 "resource exhaustion",
225 InvalidProgramInfo::AlreadyReported(_) |
226 InvalidProgramInfo::Layout(..) |
227 InvalidProgramInfo::ReferencedConstant
229 "post-monomorphization error",
231 bug!("This error should be impossible in Miri: {:?}", kind),
234 let helps = match e.kind() {
236 UnsupportedOpInfo::ThreadLocalStatic(_) |
237 UnsupportedOpInfo::ReadExternStatic(_)
239 panic!("Error should never be raised by Miri: {:?}", e.kind()),
241 UnsupportedOpInfo::Unsupported(_) |
242 UnsupportedOpInfo::PartialPointerOverwrite(_) |
243 UnsupportedOpInfo::ReadPointerAsBytes
245 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"))],
246 UndefinedBehavior(UndefinedBehaviorInfo::AlignmentCheckFailed { .. })
247 if ecx.machine.check_alignment == AlignmentCheck::Symbolic
250 (None, format!("this usually indicates that your program performed an invalid operation and caused Undefined Behavior")),
251 (None, format!("but due to `-Zmiri-symbolic-alignment-check`, alignment errors can also be false positives")),
253 UndefinedBehavior(_) =>
255 (None, format!("this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior")),
256 (None, format!("see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information")),
258 InvalidProgram(_) | ResourceExhaustion(_) | MachineStop(_) =>
265 let stacktrace = ecx.generate_stacktrace();
266 let (stacktrace, was_pruned) = prune_stacktrace(ecx, stacktrace);
268 msg.insert(0, e.to_string());
272 &if let Some(title) = title { format!("{}: {}", title, msg[0]) } else { msg[0].clone() },
278 // Include a note like `std` does when we omit frames from a backtrace
280 ecx.tcx.sess.diagnostic().note_without_error(
281 "some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace",
285 // Debug-dump all locals.
286 for (i, frame) in ecx.active_thread_stack().iter().enumerate() {
287 trace!("-------------------");
288 trace!("Frame {}", i);
289 trace!(" return: {:?}", *frame.return_place);
290 for (i, local) in frame.locals.iter().enumerate() {
291 trace!(" local {}: {:?}", i, local.value);
295 // Extra output to help debug specific issues.
297 UndefinedBehavior(UndefinedBehaviorInfo::InvalidUninitBytes(Some((alloc_id, access)))) => {
299 "Uninitialized read occurred at offsets 0x{:x}..0x{:x} into this allocation:",
300 access.uninit_offset.bytes(),
301 access.uninit_offset.bytes() + access.uninit_size.bytes(),
303 eprintln!("{:?}", ecx.dump_alloc(*alloc_id));
311 /// Report an error or note (depending on the `error` argument) with the given stacktrace.
312 /// Also emits a full stacktrace of the interpreter stack.
313 /// We want to present a multi-line span message for some errors. Diagnostics do not support this
314 /// directly, so we pass the lines as a `Vec<String>` and display each line after the first with an
315 /// additional `span_label` or `note` call.
316 fn report_msg<'mir, 'tcx>(
317 ecx: &InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
318 diag_level: DiagLevel,
320 span_msg: Vec<String>,
321 mut helps: Vec<(Option<SpanData>, String)>,
322 stacktrace: &[FrameInfo<'tcx>],
324 let span = stacktrace.first().map_or(DUMMY_SP, |fi| fi.span);
325 let sess = ecx.tcx.sess;
326 let mut err = match diag_level {
327 DiagLevel::Error => sess.struct_span_err(span, title).forget_guarantee(),
328 DiagLevel::Warning => sess.struct_span_warn(span, title),
329 DiagLevel::Note => sess.diagnostic().span_note_diag(span, title),
332 // Show main message.
333 if span != DUMMY_SP {
334 for line in span_msg {
335 err.span_label(span, line);
338 // Make sure we show the message even when it is a dummy span.
339 for line in span_msg {
342 err.note("(no span available)");
345 // Show help messages.
346 if !helps.is_empty() {
347 // Add visual separator before backtrace.
348 helps.last_mut().unwrap().1.push('\n');
349 for (span_data, help) in helps {
350 if let Some(span_data) = span_data {
351 err.span_help(span_data.span(), &help);
358 for (idx, frame_info) in stacktrace.iter().enumerate() {
359 let is_local = ecx.machine.is_local(frame_info);
360 // No span for non-local frames and the first frame (which is the error site).
361 if is_local && idx > 0 {
362 err.span_note(frame_info.span, &frame_info.to_string());
364 err.note(&frame_info.to_string());
372 static DIAGNOSTICS: RefCell<Vec<NonHaltingDiagnostic>> = RefCell::new(Vec::new());
375 /// Schedule a diagnostic for emitting. This function works even if you have no `InterpCx` available.
376 /// The diagnostic will be emitted after the current interpreter step is finished.
377 pub fn register_diagnostic(e: NonHaltingDiagnostic) {
378 DIAGNOSTICS.with(|diagnostics| diagnostics.borrow_mut().push(e));
381 /// Remember enough about the topmost frame so that we can restore the stack
382 /// after a step was taken.
383 pub struct TopFrameInfo<'tcx> {
385 instance: Option<ty::Instance<'tcx>>,
389 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
390 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
391 fn preprocess_diagnostics(&self) -> TopFrameInfo<'tcx> {
392 // Ensure we have no lingering diagnostics.
393 DIAGNOSTICS.with(|diagnostics| assert!(diagnostics.borrow().is_empty()));
395 let this = self.eval_context_ref();
396 if this.active_thread_stack().is_empty() {
397 // Diagnostics can happen even with the empty stack (e.g. deallocation of thread-local statics).
398 return TopFrameInfo { stack_size: 0, instance: None, span: DUMMY_SP };
400 let frame = this.frame();
403 stack_size: this.active_thread_stack().len(),
404 instance: Some(frame.instance),
405 span: frame.current_span(),
409 /// Emit all diagnostics that were registed with `register_diagnostics`
410 fn process_diagnostics(&self, info: TopFrameInfo<'tcx>) {
411 let this = self.eval_context_ref();
412 DIAGNOSTICS.with(|diagnostics| {
413 let mut diagnostics = diagnostics.borrow_mut();
414 if diagnostics.is_empty() {
417 // We need to fix up the stack trace, because the machine has already
418 // stepped to the next statement.
419 let mut stacktrace = this.generate_stacktrace();
420 // Remove newly pushed frames.
421 while stacktrace.len() > info.stack_size {
422 stacktrace.remove(0);
424 // Add popped frame back.
425 if stacktrace.len() < info.stack_size {
427 stacktrace.len() == info.stack_size - 1,
428 "we should never pop more than one frame at once"
430 let frame_info = FrameInfo {
431 instance: info.instance.unwrap(),
435 stacktrace.insert(0, frame_info);
436 } else if let Some(instance) = info.instance {
437 // Adjust topmost frame.
438 stacktrace[0].span = info.span;
440 stacktrace[0].instance, instance,
441 "we should not pop and push a frame in one step"
445 let (stacktrace, _was_pruned) = prune_stacktrace(this, stacktrace);
448 for e in diagnostics.drain(..) {
449 use NonHaltingDiagnostic::*;
451 CreatedPointerTag(tag) => format!("created tag {:?}", tag),
452 PoppedPointerTag(item, tag) =>
456 "popped tracked tag for item {:?} due to deallocation",
459 Some((tag, access)) => {
461 "popped tracked tag for item {:?} due to {:?} access for {:?}",
466 CreatedCallId(id) => format!("function call with id {id}"),
467 CreatedAlloc(AllocId(id), size, align, kind) =>
468 format!("created {kind} allocation of {} bytes (alignment {} bytes) with id {id}", size.bytes(), align.bytes()),
469 FreedAlloc(AllocId(id)) => format!("freed allocation with id {id}"),
470 RejectedIsolatedOp(ref op) =>
471 format!("{op} was made to return an error due to isolation"),
473 format!("progress report: current operation being executed is here"),
474 Int2Ptr { .. } => format!("integer-to-pointer cast"),
477 let (title, diag_level) = match e {
478 RejectedIsolatedOp(_) =>
479 ("operation rejected by isolation", DiagLevel::Warning),
480 Int2Ptr { .. } => ("integer-to-pointer cast", DiagLevel::Warning),
481 CreatedPointerTag(..)
482 | PoppedPointerTag(..)
486 | ProgressReport => ("tracking was triggered", DiagLevel::Note),
489 let helps = match e {
490 Int2Ptr { details: true } =>
492 (None, format!("This program is using integer-to-pointer casts or (equivalently) `ptr::from_exposed_addr`,")),
493 (None, format!("which means that Miri might miss pointer bugs in this program.")),
494 (None, format!("See https://doc.rust-lang.org/nightly/std/ptr/fn.from_exposed_addr.html for more details on that operation.")),
495 (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.")),
496 (None, format!("You can then pass the `-Zmiri-strict-provenance` flag to Miri, to ensure you are not relying on `from_exposed_addr` semantics.")),
497 (None, format!("Alternatively, the `-Zmiri-permissive-provenance` flag disables this warning.")),
502 report_msg(this, diag_level, title, vec![msg], helps, &stacktrace);