508 lines
22 KiB
Rust
508 lines
22 KiB
Rust
use std::cell::RefCell;
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use std::fmt;
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use std::num::NonZeroU64;
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use log::trace;
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use rustc_middle::ty;
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use rustc_span::{source_map::DUMMY_SP, Span, SpanData, Symbol};
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use rustc_target::abi::{Align, Size};
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use crate::stacked_borrows::{diagnostics::TagHistory, AccessKind};
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use crate::*;
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/// Details of premature program termination.
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pub enum TerminationInfo {
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Exit(i64),
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Abort(String),
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UnsupportedInIsolation(String),
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StackedBorrowsUb {
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msg: String,
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help: Option<String>,
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history: Option<TagHistory>,
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},
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Int2PtrWithStrictProvenance,
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Deadlock,
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MultipleSymbolDefinitions {
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link_name: Symbol,
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first: SpanData,
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first_crate: Symbol,
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second: SpanData,
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second_crate: Symbol,
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},
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SymbolShimClashing {
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link_name: Symbol,
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span: SpanData,
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},
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}
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impl fmt::Display for TerminationInfo {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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use TerminationInfo::*;
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match self {
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Exit(code) => write!(f, "the evaluated program completed with exit code {code}"),
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Abort(msg) => write!(f, "{msg}"),
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UnsupportedInIsolation(msg) => write!(f, "{msg}"),
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Int2PtrWithStrictProvenance =>
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write!(
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f,
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"integer-to-pointer casts and `ptr::from_exposed_addr` are not supported with `-Zmiri-strict-provenance`"
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),
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StackedBorrowsUb { msg, .. } => write!(f, "{msg}"),
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Deadlock => write!(f, "the evaluated program deadlocked"),
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MultipleSymbolDefinitions { link_name, .. } =>
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write!(f, "multiple definitions of symbol `{link_name}`"),
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SymbolShimClashing { link_name, .. } =>
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write!(f, "found `{link_name}` symbol definition that clashes with a built-in shim",),
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}
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}
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}
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impl MachineStopType for TerminationInfo {}
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/// Miri specific diagnostics
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pub enum NonHaltingDiagnostic {
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CreatedPointerTag(NonZeroU64, Option<(AllocId, AllocRange)>),
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/// This `Item` was popped from the borrow stack, either due to an access with the given tag or
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/// a deallocation when the second argument is `None`.
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PoppedPointerTag(Item, Option<(SbTagExtra, AccessKind)>),
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CreatedCallId(CallId),
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CreatedAlloc(AllocId, Size, Align, MemoryKind<MiriMemoryKind>),
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FreedAlloc(AllocId),
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RejectedIsolatedOp(String),
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ProgressReport,
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Int2Ptr {
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details: bool,
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},
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}
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/// Level of Miri specific diagnostics
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enum DiagLevel {
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Error,
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Warning,
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Note,
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}
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/// Attempts to prune a stacktrace to omit the Rust runtime, and returns a bool indicating if any
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/// frames were pruned. If the stacktrace does not have any local frames, we conclude that it must
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/// be pointing to a problem in the Rust runtime itself, and do not prune it at all.
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fn prune_stacktrace<'mir, 'tcx>(
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ecx: &InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
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mut stacktrace: Vec<FrameInfo<'tcx>>,
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) -> (Vec<FrameInfo<'tcx>>, bool) {
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match ecx.machine.backtrace_style {
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BacktraceStyle::Off => {
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// Remove all frames marked with `caller_location` -- that attribute indicates we
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// usually want to point at the caller, not them.
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stacktrace.retain(|frame| !frame.instance.def.requires_caller_location(*ecx.tcx));
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// Retain one frame so that we can print a span for the error itself
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stacktrace.truncate(1);
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(stacktrace, false)
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}
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BacktraceStyle::Short => {
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let original_len = stacktrace.len();
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// Only prune frames if there is at least one local frame. This check ensures that if
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// we get a backtrace that never makes it to the user code because it has detected a
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// bug in the Rust runtime, we don't prune away every frame.
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let has_local_frame = stacktrace.iter().any(|frame| ecx.machine.is_local(frame));
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if has_local_frame {
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// Remove all frames marked with `caller_location` -- that attribute indicates we
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// usually want to point at the caller, not them.
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stacktrace.retain(|frame| !frame.instance.def.requires_caller_location(*ecx.tcx));
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// This is part of the logic that `std` uses to select the relevant part of a
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// backtrace. But here, we only look for __rust_begin_short_backtrace, not
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// __rust_end_short_backtrace because the end symbol comes from a call to the default
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// panic handler.
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stacktrace = stacktrace
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.into_iter()
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.take_while(|frame| {
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let def_id = frame.instance.def_id();
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let path = ecx.tcx.tcx.def_path_str(def_id);
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!path.contains("__rust_begin_short_backtrace")
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})
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.collect::<Vec<_>>();
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// After we prune frames from the bottom, there are a few left that are part of the
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// Rust runtime. So we remove frames until we get to a local symbol, which should be
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// main or a test.
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// This len check ensures that we don't somehow remove every frame, as doing so breaks
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// the primary error message.
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while stacktrace.len() > 1
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&& stacktrace.last().map_or(false, |frame| !ecx.machine.is_local(frame))
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{
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stacktrace.pop();
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}
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}
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let was_pruned = stacktrace.len() != original_len;
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(stacktrace, was_pruned)
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}
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BacktraceStyle::Full => (stacktrace, false),
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}
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}
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/// Emit a custom diagnostic without going through the miri-engine machinery
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pub fn report_error<'tcx, 'mir>(
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ecx: &InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
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e: InterpErrorInfo<'tcx>,
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) -> Option<i64> {
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use InterpError::*;
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let mut msg = vec![];
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let (title, helps) = match &e.kind() {
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MachineStop(info) => {
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let info = info.downcast_ref::<TerminationInfo>().expect("invalid MachineStop payload");
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use TerminationInfo::*;
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let title = match info {
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Exit(code) => return Some(*code),
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Abort(_) => Some("abnormal termination"),
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UnsupportedInIsolation(_) | Int2PtrWithStrictProvenance =>
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Some("unsupported operation"),
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StackedBorrowsUb { .. } => Some("Undefined Behavior"),
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Deadlock => Some("deadlock"),
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MultipleSymbolDefinitions { .. } | SymbolShimClashing { .. } => None,
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};
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#[rustfmt::skip]
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let helps = match info {
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UnsupportedInIsolation(_) =>
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vec![
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(None, format!("pass the flag `-Zmiri-disable-isolation` to disable isolation;")),
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(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")),
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],
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StackedBorrowsUb { help, history, .. } => {
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let url = "https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md";
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msg.extend(help.clone());
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let mut helps = vec![
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(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")),
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(None, format!("see {url} for further information")),
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];
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match history {
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Some(TagHistory::Tagged {tag, created: (created_range, created_span), invalidated, protected }) => {
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let msg = format!("{tag:?} was created by a retag at offsets {created_range:?}");
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helps.push((Some(*created_span), msg));
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if let Some((invalidated_range, invalidated_span)) = invalidated {
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let msg = format!("{tag:?} was later invalidated at offsets {invalidated_range:?}");
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helps.push((Some(*invalidated_span), msg));
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}
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if let Some((protecting_tag, protecting_tag_span, protection_span)) = protected {
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helps.push((Some(*protecting_tag_span), format!("{tag:?} was protected due to {protecting_tag:?} which was created here")));
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helps.push((Some(*protection_span), format!("this protector is live for this call")));
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}
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}
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None => {}
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}
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helps
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}
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MultipleSymbolDefinitions { first, first_crate, second, second_crate, .. } =>
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vec![
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(Some(*first), format!("it's first defined here, in crate `{first_crate}`")),
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(Some(*second), format!("then it's defined here again, in crate `{second_crate}`")),
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],
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SymbolShimClashing { link_name, span } =>
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vec![(Some(*span), format!("the `{link_name}` symbol is defined here"))],
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Int2PtrWithStrictProvenance =>
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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"))],
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_ => vec![],
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};
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(title, helps)
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}
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_ => {
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#[rustfmt::skip]
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let title = match e.kind() {
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Unsupported(_) =>
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"unsupported operation",
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UndefinedBehavior(_) =>
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"Undefined Behavior",
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ResourceExhaustion(_) =>
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"resource exhaustion",
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InvalidProgram(
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InvalidProgramInfo::AlreadyReported(_) |
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InvalidProgramInfo::Layout(..) |
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InvalidProgramInfo::ReferencedConstant
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) =>
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"post-monomorphization error",
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kind =>
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bug!("This error should be impossible in Miri: {kind:?}"),
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};
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#[rustfmt::skip]
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let helps = match e.kind() {
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Unsupported(
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UnsupportedOpInfo::ThreadLocalStatic(_) |
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UnsupportedOpInfo::ReadExternStatic(_)
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) =>
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panic!("Error should never be raised by Miri: {kind:?}", kind = e.kind()),
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Unsupported(
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UnsupportedOpInfo::Unsupported(_) |
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UnsupportedOpInfo::PartialPointerOverwrite(_) |
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UnsupportedOpInfo::ReadPointerAsBytes
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) =>
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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"))],
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UndefinedBehavior(UndefinedBehaviorInfo::AlignmentCheckFailed { .. })
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if ecx.machine.check_alignment == AlignmentCheck::Symbolic
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=>
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vec![
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(None, format!("this usually indicates that your program performed an invalid operation and caused Undefined Behavior")),
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(None, format!("but due to `-Zmiri-symbolic-alignment-check`, alignment errors can also be false positives")),
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],
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UndefinedBehavior(_) =>
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vec![
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(None, format!("this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior")),
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(None, format!("see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information")),
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],
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InvalidProgram(_) | ResourceExhaustion(_) | MachineStop(_) =>
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vec![],
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};
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(Some(title), helps)
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}
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};
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let stacktrace = ecx.generate_stacktrace();
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let (stacktrace, was_pruned) = prune_stacktrace(ecx, stacktrace);
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e.print_backtrace();
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msg.insert(0, e.to_string());
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report_msg(
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ecx,
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DiagLevel::Error,
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&if let Some(title) = title { format!("{}: {}", title, msg[0]) } else { msg[0].clone() },
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msg,
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helps,
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&stacktrace,
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);
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// Include a note like `std` does when we omit frames from a backtrace
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if was_pruned {
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ecx.tcx.sess.diagnostic().note_without_error(
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"some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace",
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);
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}
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// Debug-dump all locals.
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for (i, frame) in ecx.active_thread_stack().iter().enumerate() {
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trace!("-------------------");
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trace!("Frame {}", i);
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trace!(" return: {:?}", *frame.return_place);
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for (i, local) in frame.locals.iter().enumerate() {
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trace!(" local {}: {:?}", i, local.value);
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}
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}
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// Extra output to help debug specific issues.
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match e.kind() {
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UndefinedBehavior(UndefinedBehaviorInfo::InvalidUninitBytes(Some((alloc_id, access)))) => {
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eprintln!(
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"Uninitialized memory occurred at {alloc_id:?}{range:?}, in this allocation:",
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range = access.uninit,
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);
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eprintln!("{:?}", ecx.dump_alloc(*alloc_id));
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}
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_ => {}
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}
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None
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}
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/// Report an error or note (depending on the `error` argument) with the given stacktrace.
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/// Also emits a full stacktrace of the interpreter stack.
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/// We want to present a multi-line span message for some errors. Diagnostics do not support this
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/// directly, so we pass the lines as a `Vec<String>` and display each line after the first with an
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/// additional `span_label` or `note` call.
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fn report_msg<'mir, 'tcx>(
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ecx: &InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
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diag_level: DiagLevel,
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title: &str,
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span_msg: Vec<String>,
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helps: Vec<(Option<SpanData>, String)>,
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stacktrace: &[FrameInfo<'tcx>],
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) {
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let span = stacktrace.first().map_or(DUMMY_SP, |fi| fi.span);
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let sess = ecx.tcx.sess;
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let mut err = match diag_level {
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DiagLevel::Error => sess.struct_span_err(span, title).forget_guarantee(),
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DiagLevel::Warning => sess.struct_span_warn(span, title),
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DiagLevel::Note => sess.diagnostic().span_note_diag(span, title),
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};
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// Show main message.
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if span != DUMMY_SP {
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for line in span_msg {
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err.span_label(span, line);
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}
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} else {
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// Make sure we show the message even when it is a dummy span.
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for line in span_msg {
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err.note(&line);
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}
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err.note("(no span available)");
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}
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// Show help messages.
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if !helps.is_empty() {
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for (span_data, help) in helps {
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if let Some(span_data) = span_data {
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err.span_help(span_data.span(), &help);
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} else {
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err.help(&help);
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}
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}
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// Add visual separator before backtrace.
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err.note("backtrace:");
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}
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// Add backtrace
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for (idx, frame_info) in stacktrace.iter().enumerate() {
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let is_local = ecx.machine.is_local(frame_info);
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// No span for non-local frames and the first frame (which is the error site).
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if is_local && idx > 0 {
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err.span_note(frame_info.span, &frame_info.to_string());
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} else {
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err.note(&frame_info.to_string());
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}
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}
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err.emit();
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}
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thread_local! {
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static DIAGNOSTICS: RefCell<Vec<NonHaltingDiagnostic>> = RefCell::new(Vec::new());
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}
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/// Schedule a diagnostic for emitting. This function works even if you have no `InterpCx` available.
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/// The diagnostic will be emitted after the current interpreter step is finished.
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pub fn register_diagnostic(e: NonHaltingDiagnostic) {
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DIAGNOSTICS.with(|diagnostics| diagnostics.borrow_mut().push(e));
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}
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/// Remember enough about the topmost frame so that we can restore the stack
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/// after a step was taken.
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pub struct TopFrameInfo<'tcx> {
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stack_size: usize,
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instance: Option<ty::Instance<'tcx>>,
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span: Span,
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}
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impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
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pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
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fn preprocess_diagnostics(&self) -> TopFrameInfo<'tcx> {
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// Ensure we have no lingering diagnostics.
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DIAGNOSTICS.with(|diagnostics| assert!(diagnostics.borrow().is_empty()));
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let this = self.eval_context_ref();
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if this.active_thread_stack().is_empty() {
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// Diagnostics can happen even with the empty stack (e.g. deallocation of thread-local statics).
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return TopFrameInfo { stack_size: 0, instance: None, span: DUMMY_SP };
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}
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let frame = this.frame();
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TopFrameInfo {
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stack_size: this.active_thread_stack().len(),
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instance: Some(frame.instance),
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span: frame.current_span(),
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}
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}
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/// Emit all diagnostics that were registed with `register_diagnostics`
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fn process_diagnostics(&self, info: TopFrameInfo<'tcx>) {
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let this = self.eval_context_ref();
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DIAGNOSTICS.with(|diagnostics| {
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let mut diagnostics = diagnostics.borrow_mut();
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if diagnostics.is_empty() {
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return;
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}
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// We need to fix up the stack trace, because the machine has already
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// stepped to the next statement.
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let mut stacktrace = this.generate_stacktrace();
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// Remove newly pushed frames.
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while stacktrace.len() > info.stack_size {
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stacktrace.remove(0);
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}
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// Add popped frame back.
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if stacktrace.len() < info.stack_size {
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assert!(
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stacktrace.len() == info.stack_size - 1,
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"we should never pop more than one frame at once"
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);
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let frame_info = FrameInfo {
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instance: info.instance.unwrap(),
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span: info.span,
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lint_root: None,
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};
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stacktrace.insert(0, frame_info);
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} else if let Some(instance) = info.instance {
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// Adjust topmost frame.
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stacktrace[0].span = info.span;
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assert_eq!(
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stacktrace[0].instance, instance,
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"we should not pop and push a frame in one step"
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);
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}
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let (stacktrace, _was_pruned) = prune_stacktrace(this, stacktrace);
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// Show diagnostics.
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for e in diagnostics.drain(..) {
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use NonHaltingDiagnostic::*;
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let msg = match e {
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CreatedPointerTag(tag, None) =>
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format!("created tag {tag:?}"),
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CreatedPointerTag(tag, Some((alloc_id, range))) =>
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format!("created tag {tag:?} at {alloc_id:?}{range:?}"),
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PoppedPointerTag(item, tag) =>
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match tag {
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None =>
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format!(
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"popped tracked tag for item {item:?} due to deallocation",
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),
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Some((tag, access)) => {
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format!(
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"popped tracked tag for item {item:?} due to {access:?} access for {tag:?}",
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)
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}
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},
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CreatedCallId(id) =>
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format!("function call with id {id}"),
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CreatedAlloc(AllocId(id), size, align, kind) =>
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format!(
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"created {kind} allocation of {size} bytes (alignment {align} bytes) with id {id}",
|
|
size = size.bytes(),
|
|
align = align.bytes(),
|
|
),
|
|
FreedAlloc(AllocId(id)) =>
|
|
format!("freed allocation with id {id}"),
|
|
RejectedIsolatedOp(ref op) =>
|
|
format!("{op} was made to return an error due to isolation"),
|
|
ProgressReport =>
|
|
format!("progress report: current operation being executed is here"),
|
|
Int2Ptr { .. } =>
|
|
format!("integer-to-pointer cast"),
|
|
};
|
|
|
|
let (title, diag_level) = match e {
|
|
RejectedIsolatedOp(_) =>
|
|
("operation rejected by isolation", DiagLevel::Warning),
|
|
Int2Ptr { .. } => ("integer-to-pointer cast", DiagLevel::Warning),
|
|
CreatedPointerTag(..)
|
|
| PoppedPointerTag(..)
|
|
| CreatedCallId(..)
|
|
| CreatedAlloc(..)
|
|
| FreedAlloc(..)
|
|
| ProgressReport => ("tracking was triggered", DiagLevel::Note),
|
|
};
|
|
|
|
let helps = match e {
|
|
Int2Ptr { details: true } =>
|
|
vec![
|
|
(None, format!("This program is using integer-to-pointer casts or (equivalently) `ptr::from_exposed_addr`,")),
|
|
(None, format!("which means that Miri might miss pointer bugs in this program.")),
|
|
(None, format!("See https://doc.rust-lang.org/nightly/std/ptr/fn.from_exposed_addr.html for more details on that operation.")),
|
|
(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.")),
|
|
(None, format!("You can then pass the `-Zmiri-strict-provenance` flag to Miri, to ensure you are not relying on `from_exposed_addr` semantics.")),
|
|
(None, format!("Alternatively, the `-Zmiri-permissive-provenance` flag disables this warning.")),
|
|
],
|
|
_ => vec![],
|
|
};
|
|
|
|
report_msg(this, diag_level, title, vec![msg], helps, &stacktrace);
|
|
}
|
|
});
|
|
}
|
|
}
|