1 use std::cell::RefCell;
3 use std::num::NonZeroU64;
8 use rustc_span::{source_map::DUMMY_SP, Span, SpanData, Symbol};
10 use crate::helpers::HexRange;
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, .. } =>
58 "found `{}` symbol definition that clashes with a built-in shim",
65 impl MachineStopType for TerminationInfo {}
67 /// Miri specific diagnostics
68 pub enum NonHaltingDiagnostic {
69 CreatedPointerTag(NonZeroU64),
70 /// This `Item` was popped from the borrow stack, either due to an access with the given tag or
71 /// a deallocation when the second argument is `None`.
72 PoppedPointerTag(Item, Option<(SbTagExtra, AccessKind)>),
73 CreatedCallId(CallId),
74 CreatedAlloc(AllocId),
76 RejectedIsolatedOp(String),
83 /// Level of Miri specific diagnostics
90 /// Attempts to prune a stacktrace to omit the Rust runtime, and returns a bool indicating if any
91 /// frames were pruned. If the stacktrace does not have any local frames, we conclude that it must
92 /// be pointing to a problem in the Rust runtime itself, and do not prune it at all.
93 fn prune_stacktrace<'mir, 'tcx>(
94 ecx: &InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
95 mut stacktrace: Vec<FrameInfo<'tcx>>,
96 ) -> (Vec<FrameInfo<'tcx>>, bool) {
97 match ecx.machine.backtrace_style {
98 BacktraceStyle::Off => {
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 // This is part of the logic that `std` uses to select the relevant part of a
111 // backtrace. But here, we only look for __rust_begin_short_backtrace, not
112 // __rust_end_short_backtrace because the end symbol comes from a call to the default
114 stacktrace = stacktrace
116 .take_while(|frame| {
117 let def_id = frame.instance.def_id();
118 let path = ecx.tcx.tcx.def_path_str(def_id);
119 !path.contains("__rust_begin_short_backtrace")
121 .collect::<Vec<_>>();
123 // After we prune frames from the bottom, there are a few left that are part of the
124 // Rust runtime. So we remove frames until we get to a local symbol, which should be
126 // This len check ensures that we don't somehow remove every frame, as doing so breaks
127 // the primary error message.
128 while stacktrace.len() > 1
129 && stacktrace.last().map_or(false, |frame| !ecx.machine.is_local(frame))
134 let was_pruned = stacktrace.len() != original_len;
135 (stacktrace, was_pruned)
137 BacktraceStyle::Full => (stacktrace, false),
141 /// Emit a custom diagnostic without going through the miri-engine machinery
142 pub fn report_error<'tcx, 'mir>(
143 ecx: &InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
144 e: InterpErrorInfo<'tcx>,
148 let mut msg = vec![];
150 let (title, helps) = match &e.kind() {
151 MachineStop(info) => {
152 let info = info.downcast_ref::<TerminationInfo>().expect("invalid MachineStop payload");
153 use TerminationInfo::*;
154 let title = match info {
155 Exit(code) => return Some(*code),
156 Abort(_) => Some("abnormal termination"),
157 UnsupportedInIsolation(_) | Int2PtrWithStrictProvenance =>
158 Some("unsupported operation"),
159 StackedBorrowsUb { .. } => Some("Undefined Behavior"),
160 Deadlock => Some("deadlock"),
161 MultipleSymbolDefinitions { .. } | SymbolShimClashing { .. } => None,
164 let helps = match info {
165 UnsupportedInIsolation(_) =>
167 (None, format!("pass the flag `-Zmiri-disable-isolation` to disable isolation;")),
168 (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")),
170 StackedBorrowsUb { help, history, .. } => {
171 let url = "https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md";
172 msg.extend(help.clone());
173 let mut helps = vec![
174 (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")),
175 (None, format!("see {url} for further information")),
178 Some(TagHistory::Tagged {tag, created: (created_range, created_span), invalidated, protected }) => {
179 let msg = format!("{:?} was created by a retag at offsets {}", tag, HexRange(*created_range));
180 helps.push((Some(*created_span), msg));
181 if let Some((invalidated_range, invalidated_span)) = invalidated {
182 let msg = format!("{:?} was later invalidated at offsets {}", tag, HexRange(*invalidated_range));
183 helps.push((Some(*invalidated_span), msg));
185 if let Some((protecting_tag, protecting_tag_span, protection_span)) = protected {
186 helps.push((Some(*protecting_tag_span), format!("{:?} was protected due to {:?} which was created here", tag, protecting_tag)));
187 helps.push((Some(*protection_span), format!("this protector is live for this call")));
194 MultipleSymbolDefinitions { first, first_crate, second, second_crate, .. } =>
196 (Some(*first), format!("it's first defined here, in crate `{}`", first_crate)),
197 (Some(*second), format!("then it's defined here again, in crate `{}`", second_crate)),
199 SymbolShimClashing { link_name, span } =>
200 vec![(Some(*span), format!("the `{}` symbol is defined here", link_name))],
201 Int2PtrWithStrictProvenance =>
202 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"))],
209 let title = match e.kind() {
211 "unsupported operation",
212 UndefinedBehavior(_) =>
213 "Undefined Behavior",
214 ResourceExhaustion(_) =>
215 "resource exhaustion",
217 InvalidProgramInfo::AlreadyReported(_) |
218 InvalidProgramInfo::Layout(..) |
219 InvalidProgramInfo::ReferencedConstant
221 "post-monomorphization error",
223 bug!("This error should be impossible in Miri: {:?}", kind),
226 let helps = match e.kind() {
228 UnsupportedOpInfo::ThreadLocalStatic(_) |
229 UnsupportedOpInfo::ReadExternStatic(_)
231 panic!("Error should never be raised by Miri: {:?}", e.kind()),
233 UnsupportedOpInfo::Unsupported(_) |
234 UnsupportedOpInfo::PartialPointerOverwrite(_) |
235 UnsupportedOpInfo::ReadPointerAsBytes
237 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"))],
238 UndefinedBehavior(UndefinedBehaviorInfo::AlignmentCheckFailed { .. })
239 if ecx.machine.check_alignment == AlignmentCheck::Symbolic
242 (None, format!("this usually indicates that your program performed an invalid operation and caused Undefined Behavior")),
243 (None, format!("but due to `-Zmiri-symbolic-alignment-check`, alignment errors can also be false positives")),
245 UndefinedBehavior(_) =>
247 (None, format!("this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior")),
248 (None, format!("see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information")),
250 InvalidProgram(_) | ResourceExhaustion(_) | MachineStop(_) =>
257 let stacktrace = ecx.generate_stacktrace();
258 let (stacktrace, was_pruned) = prune_stacktrace(ecx, stacktrace);
260 msg.insert(0, e.to_string());
264 &if let Some(title) = title { format!("{}: {}", title, msg[0]) } else { msg[0].clone() },
270 // Include a note like `std` does when we omit frames from a backtrace
272 ecx.tcx.sess.diagnostic().note_without_error(
273 "some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace",
277 // Debug-dump all locals.
278 for (i, frame) in ecx.active_thread_stack().iter().enumerate() {
279 trace!("-------------------");
280 trace!("Frame {}", i);
281 trace!(" return: {:?}", *frame.return_place);
282 for (i, local) in frame.locals.iter().enumerate() {
283 trace!(" local {}: {:?}", i, local.value);
287 // Extra output to help debug specific issues.
289 UndefinedBehavior(UndefinedBehaviorInfo::InvalidUninitBytes(Some((alloc_id, access)))) => {
291 "Uninitialized read occurred at offsets 0x{:x}..0x{:x} into this allocation:",
292 access.uninit_offset.bytes(),
293 access.uninit_offset.bytes() + access.uninit_size.bytes(),
295 eprintln!("{:?}", ecx.dump_alloc(*alloc_id));
303 /// Report an error or note (depending on the `error` argument) with the given stacktrace.
304 /// Also emits a full stacktrace of the interpreter stack.
305 /// We want to present a multi-line span message for some errors. Diagnostics do not support this
306 /// directly, so we pass the lines as a `Vec<String>` and display each line after the first with an
307 /// additional `span_label` or `note` call.
308 fn report_msg<'mir, 'tcx>(
309 ecx: &InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
310 diag_level: DiagLevel,
312 span_msg: Vec<String>,
313 mut helps: Vec<(Option<SpanData>, String)>,
314 stacktrace: &[FrameInfo<'tcx>],
316 let span = stacktrace.first().map_or(DUMMY_SP, |fi| fi.span);
317 let sess = ecx.tcx.sess;
318 let mut err = match diag_level {
319 DiagLevel::Error => sess.struct_span_err(span, title).forget_guarantee(),
320 DiagLevel::Warning => sess.struct_span_warn(span, title),
321 DiagLevel::Note => sess.diagnostic().span_note_diag(span, title),
324 // Show main message.
325 if span != DUMMY_SP {
326 for line in span_msg {
327 err.span_label(span, line);
330 // Make sure we show the message even when it is a dummy span.
331 for line in span_msg {
334 err.note("(no span available)");
337 // Show help messages.
338 if !helps.is_empty() {
339 // Add visual separator before backtrace.
340 helps.last_mut().unwrap().1.push('\n');
341 for (span_data, help) in helps {
342 if let Some(span_data) = span_data {
343 err.span_help(span_data.span(), &help);
350 for (idx, frame_info) in stacktrace.iter().enumerate() {
351 let is_local = ecx.machine.is_local(frame_info);
352 // No span for non-local frames and the first frame (which is the error site).
353 if is_local && idx > 0 {
354 err.span_note(frame_info.span, &frame_info.to_string());
356 err.note(&frame_info.to_string());
364 static DIAGNOSTICS: RefCell<Vec<NonHaltingDiagnostic>> = RefCell::new(Vec::new());
367 /// Schedule a diagnostic for emitting. This function works even if you have no `InterpCx` available.
368 /// The diagnostic will be emitted after the current interpreter step is finished.
369 pub fn register_diagnostic(e: NonHaltingDiagnostic) {
370 DIAGNOSTICS.with(|diagnostics| diagnostics.borrow_mut().push(e));
373 /// Remember enough about the topmost frame so that we can restore the stack
374 /// after a step was taken.
375 pub struct TopFrameInfo<'tcx> {
377 instance: Option<ty::Instance<'tcx>>,
381 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
382 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
383 fn preprocess_diagnostics(&self) -> TopFrameInfo<'tcx> {
384 // Ensure we have no lingering diagnostics.
385 DIAGNOSTICS.with(|diagnostics| assert!(diagnostics.borrow().is_empty()));
387 let this = self.eval_context_ref();
388 if this.active_thread_stack().is_empty() {
389 // Diagnostics can happen even with the empty stack (e.g. deallocation of thread-local statics).
390 return TopFrameInfo { stack_size: 0, instance: None, span: DUMMY_SP };
392 let frame = this.frame();
395 stack_size: this.active_thread_stack().len(),
396 instance: Some(frame.instance),
397 span: frame.current_span(),
401 /// Emit all diagnostics that were registed with `register_diagnostics`
402 fn process_diagnostics(&self, info: TopFrameInfo<'tcx>) {
403 let this = self.eval_context_ref();
404 DIAGNOSTICS.with(|diagnostics| {
405 let mut diagnostics = diagnostics.borrow_mut();
406 if diagnostics.is_empty() {
409 // We need to fix up the stack trace, because the machine has already
410 // stepped to the next statement.
411 let mut stacktrace = this.generate_stacktrace();
412 // Remove newly pushed frames.
413 while stacktrace.len() > info.stack_size {
414 stacktrace.remove(0);
416 // Add popped frame back.
417 if stacktrace.len() < info.stack_size {
419 stacktrace.len() == info.stack_size - 1,
420 "we should never pop more than one frame at once"
422 let frame_info = FrameInfo {
423 instance: info.instance.unwrap(),
427 stacktrace.insert(0, frame_info);
428 } else if let Some(instance) = info.instance {
429 // Adjust topmost frame.
430 stacktrace[0].span = info.span;
432 stacktrace[0].instance, instance,
433 "we should not pop and push a frame in one step"
437 let (stacktrace, _was_pruned) = prune_stacktrace(this, stacktrace);
440 for e in diagnostics.drain(..) {
441 use NonHaltingDiagnostic::*;
443 CreatedPointerTag(tag) => format!("created tag {:?}", tag),
444 PoppedPointerTag(item, tag) =>
448 "popped tracked tag for item {:?} due to deallocation",
451 Some((tag, access)) => {
453 "popped tracked tag for item {:?} due to {:?} access for {:?}",
458 CreatedCallId(id) => format!("function call with id {id}"),
459 CreatedAlloc(AllocId(id)) => format!("created allocation with id {id}"),
460 FreedAlloc(AllocId(id)) => format!("freed allocation with id {id}"),
461 RejectedIsolatedOp(ref op) =>
462 format!("{op} was made to return an error due to isolation"),
464 format!("progress report: current operation being executed is here"),
465 Int2Ptr { .. } => format!("integer-to-pointer cast"),
468 let (title, diag_level) = match e {
469 RejectedIsolatedOp(_) =>
470 ("operation rejected by isolation", DiagLevel::Warning),
471 Int2Ptr { .. } => ("integer-to-pointer cast", DiagLevel::Warning),
472 CreatedPointerTag(..)
473 | PoppedPointerTag(..)
477 | ProgressReport => ("tracking was triggered", DiagLevel::Note),
480 let helps = match e {
481 Int2Ptr { details: true } =>
483 (None, format!("This program is using integer-to-pointer casts or (equivalently) `ptr::from_exposed_addr`,")),
484 (None, format!("which means that Miri might miss pointer bugs in this program.")),
485 (None, format!("See https://doc.rust-lang.org/nightly/std/ptr/fn.from_exposed_addr.html for more details on that operation.")),
486 (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.")),
487 (None, format!("You can then pass the `-Zmiri-strict-provenance` flag to Miri, to ensure you are not relying on `from_exposed_addr` semantics.")),
488 (None, format!("Alternatively, the `-Zmiri-permissive-provenance` flag disables this warning.")),
493 report_msg(this, diag_level, title, vec![msg], helps, &stacktrace);