1 //! The memory subsystem.
3 //! Generally, we use `Pointer` to denote memory addresses. However, some operations
4 //! have a "size"-like parameter, and they take `Scalar` for the address because
5 //! if the size is 0, then the pointer can also be a (properly aligned, non-null)
6 //! integer. It is crucial that these operations call `check_align` *before*
7 //! short-circuiting the empty case!
9 use std::assert_matches::assert_matches;
11 use std::collections::VecDeque;
12 use std::convert::TryFrom;
16 use rustc_ast::Mutability;
17 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
18 use rustc_middle::mir::display_allocation;
19 use rustc_middle::ty::{Instance, ParamEnv, TyCtxt};
20 use rustc_target::abi::{Align, HasDataLayout, Size, TargetDataLayout};
23 alloc_range, AllocId, AllocMap, AllocRange, Allocation, CheckInAllocMsg, GlobalAlloc,
24 InterpResult, Machine, MayLeak, Pointer, PointerArithmetic, Provenance, Scalar,
28 #[derive(Debug, PartialEq, Copy, Clone)]
29 pub enum MemoryKind<T> {
30 /// Stack memory. Error if deallocated except during a stack pop.
32 /// Memory allocated by `caller_location` intrinsic. Error if ever deallocated.
34 /// Additional memory kinds a machine wishes to distinguish from the builtin ones.
38 impl<T: MayLeak> MayLeak for MemoryKind<T> {
40 fn may_leak(self) -> bool {
42 MemoryKind::Stack => false,
43 MemoryKind::CallerLocation => true,
44 MemoryKind::Machine(k) => k.may_leak(),
49 impl<T: fmt::Display> fmt::Display for MemoryKind<T> {
50 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
52 MemoryKind::Stack => write!(f, "stack variable"),
53 MemoryKind::CallerLocation => write!(f, "caller location"),
54 MemoryKind::Machine(m) => write!(f, "{}", m),
59 /// Used by `get_size_and_align` to indicate whether the allocation needs to be live.
60 #[derive(Debug, Copy, Clone)]
62 /// Allocation must be live and not a function pointer.
64 /// Allocations needs to be live, but may be a function pointer.
66 /// Allocation may be dead.
70 /// The value of a function pointer.
71 #[derive(Debug, Copy, Clone)]
72 pub enum FnVal<'tcx, Other> {
73 Instance(Instance<'tcx>),
77 impl<'tcx, Other> FnVal<'tcx, Other> {
78 pub fn as_instance(self) -> InterpResult<'tcx, Instance<'tcx>> {
80 FnVal::Instance(instance) => Ok(instance),
82 throw_unsup_format!("'foreign' function pointers are not supported in this context")
88 // `Memory` has to depend on the `Machine` because some of its operations
89 // (e.g., `get`) call a `Machine` hook.
90 pub struct Memory<'mir, 'tcx, M: Machine<'mir, 'tcx>> {
91 /// Allocations local to this instance of the miri engine. The kind
92 /// helps ensure that the same mechanism is used for allocation and
93 /// deallocation. When an allocation is not found here, it is a
94 /// global and looked up in the `tcx` for read access. Some machines may
95 /// have to mutate this map even on a read-only access to a global (because
96 /// they do pointer provenance tracking and the allocations in `tcx` have
97 /// the wrong type), so we let the machine override this type.
98 /// Either way, if the machine allows writing to a global, doing so will
99 /// create a copy of the global allocation here.
100 // FIXME: this should not be public, but interning currently needs access to it
101 pub(super) alloc_map: M::MemoryMap,
103 /// Map for "extra" function pointers.
104 extra_fn_ptr_map: FxHashMap<AllocId, M::ExtraFnVal>,
106 /// To be able to compare pointers with null, and to check alignment for accesses
107 /// to ZSTs (where pointers may dangle), we keep track of the size even for allocations
108 /// that do not exist any more.
109 // FIXME: this should not be public, but interning currently needs access to it
110 pub(super) dead_alloc_map: FxHashMap<AllocId, (Size, Align)>,
112 /// Extra data added by the machine.
113 pub extra: M::MemoryExtra,
115 /// Lets us implement `HasDataLayout`, which is awfully convenient.
116 pub tcx: TyCtxt<'tcx>,
119 impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> HasDataLayout for Memory<'mir, 'tcx, M> {
121 fn data_layout(&self) -> &TargetDataLayout {
122 &self.tcx.data_layout
126 /// A reference to some allocation that was already bounds-checked for the given region
127 /// and had the on-access machine hooks run.
128 #[derive(Copy, Clone)]
129 pub struct AllocRef<'a, 'tcx, Tag, Extra> {
130 alloc: &'a Allocation<Tag, Extra>,
135 /// A reference to some allocation that was already bounds-checked for the given region
136 /// and had the on-access machine hooks run.
137 pub struct AllocRefMut<'a, 'tcx, Tag, Extra> {
138 alloc: &'a mut Allocation<Tag, Extra>,
144 impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
145 pub fn new(tcx: TyCtxt<'tcx>, extra: M::MemoryExtra) -> Self {
147 alloc_map: M::MemoryMap::default(),
148 extra_fn_ptr_map: FxHashMap::default(),
149 dead_alloc_map: FxHashMap::default(),
155 /// Call this to turn untagged "global" pointers (obtained via `tcx`) into
156 /// the machine pointer to the allocation. Must never be used
157 /// for any other pointers, nor for TLS statics.
159 /// Using the resulting pointer represents a *direct* access to that memory
160 /// (e.g. by directly using a `static`),
161 /// as opposed to access through a pointer that was created by the program.
163 /// This function can fail only if `ptr` points to an `extern static`.
165 pub fn global_base_pointer(
167 ptr: Pointer<AllocId>,
168 ) -> InterpResult<'tcx, Pointer<M::PointerTag>> {
169 // We know `offset` is relative to the allocation, so we can use `into_parts`.
170 let (alloc_id, offset) = ptr.into_parts();
171 // We need to handle `extern static`.
172 match self.tcx.get_global_alloc(alloc_id) {
173 Some(GlobalAlloc::Static(def_id)) if self.tcx.is_thread_local_static(def_id) => {
174 bug!("global memory cannot point to thread-local static")
176 Some(GlobalAlloc::Static(def_id)) if self.tcx.is_foreign_item(def_id) => {
177 return M::extern_static_base_pointer(self, def_id);
181 // And we need to get the tag.
182 Ok(M::tag_alloc_base_pointer(self, Pointer::new(alloc_id, offset)))
185 pub fn create_fn_alloc(
187 fn_val: FnVal<'tcx, M::ExtraFnVal>,
188 ) -> Pointer<M::PointerTag> {
189 let id = match fn_val {
190 FnVal::Instance(instance) => self.tcx.create_fn_alloc(instance),
191 FnVal::Other(extra) => {
192 // FIXME(RalfJung): Should we have a cache here?
193 let id = self.tcx.reserve_alloc_id();
194 let old = self.extra_fn_ptr_map.insert(id, extra);
195 assert!(old.is_none());
199 // Functions are global allocations, so make sure we get the right base pointer.
200 // We know this is not an `extern static` so this cannot fail.
201 self.global_base_pointer(Pointer::from(id)).unwrap()
208 kind: MemoryKind<M::MemoryKind>,
209 ) -> InterpResult<'static, Pointer<M::PointerTag>> {
210 let alloc = Allocation::uninit(size, align, M::PANIC_ON_ALLOC_FAIL)?;
211 Ok(self.allocate_with(alloc, kind))
214 pub fn allocate_bytes(
218 kind: MemoryKind<M::MemoryKind>,
219 mutability: Mutability,
220 ) -> Pointer<M::PointerTag> {
221 let alloc = Allocation::from_bytes(bytes, align, mutability);
222 self.allocate_with(alloc, kind)
225 pub fn allocate_with(
228 kind: MemoryKind<M::MemoryKind>,
229 ) -> Pointer<M::PointerTag> {
230 let id = self.tcx.reserve_alloc_id();
233 M::GLOBAL_KIND.map(MemoryKind::Machine),
234 "dynamically allocating global memory"
236 let alloc = M::init_allocation_extra(self, id, Cow::Owned(alloc), Some(kind));
237 self.alloc_map.insert(id, (kind, alloc.into_owned()));
238 M::tag_alloc_base_pointer(self, Pointer::from(id))
243 ptr: Pointer<Option<M::PointerTag>>,
244 old_size_and_align: Option<(Size, Align)>,
247 kind: MemoryKind<M::MemoryKind>,
248 ) -> InterpResult<'tcx, Pointer<M::PointerTag>> {
249 let (alloc_id, offset, ptr) = self.ptr_get_alloc(ptr)?;
250 if offset.bytes() != 0 {
252 "reallocating {:?} which does not point to the beginning of an object",
257 // For simplicities' sake, we implement reallocate as "alloc, copy, dealloc".
258 // This happens so rarely, the perf advantage is outweighed by the maintenance cost.
259 let new_ptr = self.allocate(new_size, new_align, kind)?;
260 let old_size = match old_size_and_align {
261 Some((size, _align)) => size,
262 None => self.get_raw(alloc_id)?.size(),
264 // This will also call the access hooks.
270 old_size.min(new_size),
271 /*nonoverlapping*/ true,
273 self.deallocate(ptr.into(), old_size_and_align, kind)?;
280 ptr: Pointer<Option<M::PointerTag>>,
281 old_size_and_align: Option<(Size, Align)>,
282 kind: MemoryKind<M::MemoryKind>,
283 ) -> InterpResult<'tcx> {
284 let (alloc_id, offset, ptr) = self.ptr_get_alloc(ptr)?;
285 trace!("deallocating: {}", alloc_id);
287 if offset.bytes() != 0 {
289 "deallocating {:?} which does not point to the beginning of an object",
294 let Some((alloc_kind, mut alloc)) = self.alloc_map.remove(&alloc_id) else {
295 // Deallocating global memory -- always an error
296 return Err(match self.tcx.get_global_alloc(alloc_id) {
297 Some(GlobalAlloc::Function(..)) => {
298 err_ub_format!("deallocating {}, which is a function", alloc_id)
300 Some(GlobalAlloc::Static(..) | GlobalAlloc::Memory(..)) => {
301 err_ub_format!("deallocating {}, which is static memory", alloc_id)
303 None => err_ub!(PointerUseAfterFree(alloc_id)),
308 if alloc.mutability == Mutability::Not {
309 throw_ub_format!("deallocating immutable allocation {}", alloc_id);
311 if alloc_kind != kind {
313 "deallocating {}, which is {} memory, using {} deallocation operation",
319 if let Some((size, align)) = old_size_and_align {
320 if size != alloc.size() || align != alloc.align {
322 "incorrect layout on deallocation: {} has size {} and alignment {}, but gave size {} and alignment {}",
324 alloc.size().bytes(),
332 // Let the machine take some extra action
333 let size = alloc.size();
334 M::memory_deallocated(
338 alloc_range(Size::ZERO, size),
341 // Don't forget to remember size and align of this now-dead allocation
342 let old = self.dead_alloc_map.insert(alloc_id, (size, alloc.align));
344 bug!("Nothing can be deallocated twice");
350 /// Internal helper function to determine the allocation and offset of a pointer (if any).
354 ptr: Pointer<Option<M::PointerTag>>,
357 ) -> InterpResult<'tcx, Option<(AllocId, Size, Pointer<M::PointerTag>)>> {
358 let align = M::enforce_alignment(&self.extra).then_some(align);
359 self.check_and_deref_ptr(
363 CheckInAllocMsg::MemoryAccessTest,
364 |alloc_id, offset, ptr| {
366 self.get_size_and_align(alloc_id, AllocCheck::Dereferenceable)?;
367 Ok((size, align, (alloc_id, offset, ptr)))
372 /// Check if the given pointer points to live memory of given `size` and `align`
373 /// (ignoring `M::enforce_alignment`). The caller can control the error message for the
374 /// out-of-bounds case.
376 pub fn check_ptr_access_align(
378 ptr: Pointer<Option<M::PointerTag>>,
381 msg: CheckInAllocMsg,
382 ) -> InterpResult<'tcx> {
383 self.check_and_deref_ptr(ptr, size, Some(align), msg, |alloc_id, _, _| {
384 let check = match msg {
385 CheckInAllocMsg::DerefTest | CheckInAllocMsg::MemoryAccessTest => {
386 AllocCheck::Dereferenceable
388 CheckInAllocMsg::PointerArithmeticTest | CheckInAllocMsg::InboundsTest => {
392 let (size, align) = self.get_size_and_align(alloc_id, check)?;
393 Ok((size, align, ()))
398 /// Low-level helper function to check if a ptr is in-bounds and potentially return a reference
399 /// to the allocation it points to. Supports both shared and mutable references, as the actual
400 /// checking is offloaded to a helper closure. `align` defines whether and which alignment check
401 /// is done. Returns `None` for size 0, and otherwise `Some` of what `alloc_size` returned.
402 fn check_and_deref_ptr<T>(
404 ptr: Pointer<Option<M::PointerTag>>,
406 align: Option<Align>,
407 msg: CheckInAllocMsg,
408 alloc_size: impl FnOnce(
411 Pointer<M::PointerTag>,
412 ) -> InterpResult<'tcx, (Size, Align, T)>,
413 ) -> InterpResult<'tcx, Option<T>> {
414 fn check_offset_align(offset: u64, align: Align) -> InterpResult<'static> {
415 if offset % align.bytes() == 0 {
418 // The biggest power of two through which `offset` is divisible.
419 let offset_pow2 = 1 << offset.trailing_zeros();
420 throw_ub!(AlignmentCheckFailed {
421 has: Align::from_bytes(offset_pow2).unwrap(),
427 // Extract from the pointer an `Option<AllocId>` and an offset, which is relative to the
428 // allocation or (if that is `None`) an absolute address.
429 let ptr_or_addr = if size.bytes() == 0 {
430 // Let's see what we can do, but don't throw errors if there's nothing there.
431 self.ptr_try_get_alloc(ptr)
433 // A "real" access, we insist on getting an `AllocId`.
434 Ok(self.ptr_get_alloc(ptr)?)
436 Ok(match ptr_or_addr {
438 // No memory is actually being accessed.
439 debug_assert!(size.bytes() == 0);
442 throw_ub!(DanglingIntPointer(0, msg))
445 if let Some(align) = align {
446 check_offset_align(addr, align)?;
450 Ok((alloc_id, offset, ptr)) => {
451 let (alloc_size, alloc_align, ret_val) = alloc_size(alloc_id, offset, ptr)?;
452 // Test bounds. This also ensures non-null.
453 // It is sufficient to check this for the end pointer. Also check for overflow!
454 if offset.checked_add(size, &self.tcx).map_or(true, |end| end > alloc_size) {
455 throw_ub!(PointerOutOfBounds {
458 ptr_offset: self.machine_usize_to_isize(offset.bytes()),
463 // Test align. Check this last; if both bounds and alignment are violated
464 // we want the error to be about the bounds.
465 if let Some(align) = align {
466 if M::force_int_for_alignment_check(&self.extra) {
467 let addr = Scalar::from_pointer(ptr, &self.tcx)
468 .to_machine_usize(&self.tcx)
469 .expect("ptr-to-int cast for align check should never fail");
470 check_offset_align(addr, align)?;
472 // Check allocation alignment and offset alignment.
473 if alloc_align.bytes() < align.bytes() {
474 throw_ub!(AlignmentCheckFailed { has: alloc_align, required: align });
476 check_offset_align(offset.bytes(), align)?;
480 // We can still be zero-sized in this branch, in which case we have to
482 if size.bytes() == 0 { None } else { Some(ret_val) }
488 /// Allocation accessors
489 impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
490 /// Helper function to obtain a global (tcx) allocation.
491 /// This attempts to return a reference to an existing allocation if
492 /// one can be found in `tcx`. That, however, is only possible if `tcx` and
493 /// this machine use the same pointer tag, so it is indirected through
494 /// `M::tag_allocation`.
499 ) -> InterpResult<'tcx, Cow<'tcx, Allocation<M::PointerTag, M::AllocExtra>>> {
500 let (alloc, def_id) = match self.tcx.get_global_alloc(id) {
501 Some(GlobalAlloc::Memory(mem)) => {
502 // Memory of a constant or promoted or anonymous memory referenced by a static.
505 Some(GlobalAlloc::Function(..)) => throw_ub!(DerefFunctionPointer(id)),
506 None => throw_ub!(PointerUseAfterFree(id)),
507 Some(GlobalAlloc::Static(def_id)) => {
508 assert!(self.tcx.is_static(def_id));
509 assert!(!self.tcx.is_thread_local_static(def_id));
510 // Notice that every static has two `AllocId` that will resolve to the same
511 // thing here: one maps to `GlobalAlloc::Static`, this is the "lazy" ID,
512 // and the other one is maps to `GlobalAlloc::Memory`, this is returned by
513 // `eval_static_initializer` and it is the "resolved" ID.
514 // The resolved ID is never used by the interpreted program, it is hidden.
515 // This is relied upon for soundness of const-patterns; a pointer to the resolved
516 // ID would "sidestep" the checks that make sure consts do not point to statics!
517 // The `GlobalAlloc::Memory` branch here is still reachable though; when a static
518 // contains a reference to memory that was created during its evaluation (i.e., not
519 // to another static), those inner references only exist in "resolved" form.
520 if self.tcx.is_foreign_item(def_id) {
521 throw_unsup!(ReadExternStatic(def_id));
524 (self.tcx.eval_static_initializer(def_id)?, Some(def_id))
527 M::before_access_global(&self.extra, id, alloc, def_id, is_write)?;
528 let alloc = Cow::Borrowed(alloc);
529 // We got tcx memory. Let the machine initialize its "extra" stuff.
530 let alloc = M::init_allocation_extra(
532 id, // always use the ID we got as input, not the "hidden" one.
534 M::GLOBAL_KIND.map(MemoryKind::Machine),
539 /// Gives raw access to the `Allocation`, without bounds or alignment checks.
540 /// The caller is responsible for calling the access hooks!
544 ) -> InterpResult<'tcx, &Allocation<M::PointerTag, M::AllocExtra>> {
545 // The error type of the inner closure here is somewhat funny. We have two
546 // ways of "erroring": An actual error, or because we got a reference from
547 // `get_global_alloc` that we can actually use directly without inserting anything anywhere.
548 // So the error type is `InterpResult<'tcx, &Allocation<M::PointerTag>>`.
549 let a = self.alloc_map.get_or(id, || {
550 let alloc = self.get_global_alloc(id, /*is_write*/ false).map_err(Err)?;
552 Cow::Borrowed(alloc) => {
553 // We got a ref, cheaply return that as an "error" so that the
554 // map does not get mutated.
557 Cow::Owned(alloc) => {
558 // Need to put it into the map and return a ref to that
559 let kind = M::GLOBAL_KIND.expect(
560 "I got a global allocation that I have to copy but the machine does \
561 not expect that to happen",
563 Ok((MemoryKind::Machine(kind), alloc))
567 // Now unpack that funny error type
574 /// "Safe" (bounds and align-checked) allocation access.
577 ptr: Pointer<Option<M::PointerTag>>,
580 ) -> InterpResult<'tcx, Option<AllocRef<'a, 'tcx, M::PointerTag, M::AllocExtra>>> {
581 let align = M::enforce_alignment(&self.extra).then_some(align);
582 let ptr_and_alloc = self.check_and_deref_ptr(
586 CheckInAllocMsg::MemoryAccessTest,
587 |alloc_id, offset, ptr| {
588 let alloc = self.get_raw(alloc_id)?;
589 Ok((alloc.size(), alloc.align, (alloc_id, offset, ptr, alloc)))
592 if let Some((alloc_id, offset, ptr, alloc)) = ptr_and_alloc {
593 let range = alloc_range(offset, size);
594 M::memory_read(&self.extra, &alloc.extra, ptr.provenance, range)?;
595 Ok(Some(AllocRef { alloc, range, tcx: self.tcx, alloc_id }))
597 // Even in this branch we have to be sure that we actually access the allocation, in
598 // order to ensure that `static FOO: Type = FOO;` causes a cycle error instead of
599 // magically pulling *any* ZST value from the ether. However, the `get_raw` above is
600 // always called when `ptr` has an `AllocId`.
605 /// Return the `extra` field of the given allocation.
606 pub fn get_alloc_extra<'a>(&'a self, id: AllocId) -> InterpResult<'tcx, &'a M::AllocExtra> {
607 Ok(&self.get_raw(id)?.extra)
610 /// Gives raw mutable access to the `Allocation`, without bounds or alignment checks.
611 /// The caller is responsible for calling the access hooks!
613 /// Also returns a ptr to `self.extra` so that the caller can use it in parallel with the
618 ) -> InterpResult<'tcx, (&mut Allocation<M::PointerTag, M::AllocExtra>, &mut M::MemoryExtra)>
620 // We have "NLL problem case #3" here, which cannot be worked around without loss of
621 // efficiency even for the common case where the key is in the map.
622 // <https://rust-lang.github.io/rfcs/2094-nll.html#problem-case-3-conditional-control-flow-across-functions>
623 // (Cannot use `get_mut_or` since `get_global_alloc` needs `&self`.)
624 if self.alloc_map.get_mut(id).is_none() {
626 // Allocation not found locally, go look global.
627 let alloc = self.get_global_alloc(id, /*is_write*/ true)?;
628 let kind = M::GLOBAL_KIND.expect(
629 "I got a global allocation that I have to copy but the machine does \
630 not expect that to happen",
632 self.alloc_map.insert(id, (MemoryKind::Machine(kind), alloc.into_owned()));
635 let (_kind, alloc) = self.alloc_map.get_mut(id).unwrap();
636 if alloc.mutability == Mutability::Not {
637 throw_ub!(WriteToReadOnly(id))
639 Ok((alloc, &mut self.extra))
642 /// "Safe" (bounds and align-checked) allocation access.
645 ptr: Pointer<Option<M::PointerTag>>,
648 ) -> InterpResult<'tcx, Option<AllocRefMut<'a, 'tcx, M::PointerTag, M::AllocExtra>>> {
649 let parts = self.get_ptr_access(ptr, size, align)?;
650 if let Some((alloc_id, offset, ptr)) = parts {
652 // FIXME: can we somehow avoid looking up the allocation twice here?
653 // We cannot call `get_raw_mut` inside `check_and_deref_ptr` as that would duplicate `&mut self`.
654 let (alloc, extra) = self.get_raw_mut(alloc_id)?;
655 let range = alloc_range(offset, size);
656 M::memory_written(extra, &mut alloc.extra, ptr.provenance, range)?;
657 Ok(Some(AllocRefMut { alloc, range, tcx, alloc_id }))
663 /// Return the `extra` field of the given allocation.
664 pub fn get_alloc_extra_mut<'a>(
667 ) -> InterpResult<'tcx, (&'a mut M::AllocExtra, &'a mut M::MemoryExtra)> {
668 let (alloc, memory_extra) = self.get_raw_mut(id)?;
669 Ok((&mut alloc.extra, memory_extra))
672 /// Obtain the size and alignment of an allocation, even if that allocation has
673 /// been deallocated.
675 /// If `liveness` is `AllocCheck::MaybeDead`, this function always returns `Ok`.
676 pub fn get_size_and_align(
679 liveness: AllocCheck,
680 ) -> InterpResult<'static, (Size, Align)> {
681 // # Regular allocations
682 // Don't use `self.get_raw` here as that will
683 // a) cause cycles in case `id` refers to a static
684 // b) duplicate a global's allocation in miri
685 if let Some((_, alloc)) = self.alloc_map.get(id) {
686 return Ok((alloc.size(), alloc.align));
689 // # Function pointers
690 // (both global from `alloc_map` and local from `extra_fn_ptr_map`)
691 if self.get_fn_alloc(id).is_some() {
692 return if let AllocCheck::Dereferenceable = liveness {
693 // The caller requested no function pointers.
694 throw_ub!(DerefFunctionPointer(id))
696 Ok((Size::ZERO, Align::ONE))
701 // Can't do this in the match argument, we may get cycle errors since the lock would
702 // be held throughout the match.
703 match self.tcx.get_global_alloc(id) {
704 Some(GlobalAlloc::Static(did)) => {
705 assert!(!self.tcx.is_thread_local_static(did));
706 // Use size and align of the type.
707 let ty = self.tcx.type_of(did);
708 let layout = self.tcx.layout_of(ParamEnv::empty().and(ty)).unwrap();
709 Ok((layout.size, layout.align.abi))
711 Some(GlobalAlloc::Memory(alloc)) => {
712 // Need to duplicate the logic here, because the global allocations have
713 // different associated types than the interpreter-local ones.
714 Ok((alloc.size(), alloc.align))
716 Some(GlobalAlloc::Function(_)) => bug!("We already checked function pointers above"),
717 // The rest must be dead.
719 if let AllocCheck::MaybeDead = liveness {
720 // Deallocated pointers are allowed, we should be able to find
725 .expect("deallocated pointers should all be recorded in `dead_alloc_map`"))
727 throw_ub!(PointerUseAfterFree(id))
733 fn get_fn_alloc(&self, id: AllocId) -> Option<FnVal<'tcx, M::ExtraFnVal>> {
734 if let Some(extra) = self.extra_fn_ptr_map.get(&id) {
735 Some(FnVal::Other(*extra))
737 match self.tcx.get_global_alloc(id) {
738 Some(GlobalAlloc::Function(instance)) => Some(FnVal::Instance(instance)),
746 ptr: Pointer<Option<M::PointerTag>>,
747 ) -> InterpResult<'tcx, FnVal<'tcx, M::ExtraFnVal>> {
748 trace!("get_fn({:?})", ptr);
749 let (alloc_id, offset, _ptr) = self.ptr_get_alloc(ptr)?;
750 if offset.bytes() != 0 {
751 throw_ub!(InvalidFunctionPointer(Pointer::new(alloc_id, offset)))
753 self.get_fn_alloc(alloc_id)
754 .ok_or_else(|| err_ub!(InvalidFunctionPointer(Pointer::new(alloc_id, offset))).into())
757 pub fn mark_immutable(&mut self, id: AllocId) -> InterpResult<'tcx> {
758 self.get_raw_mut(id)?.0.mutability = Mutability::Not;
762 /// Create a lazy debug printer that prints the given allocation and all allocations it points
765 pub fn dump_alloc<'a>(&'a self, id: AllocId) -> DumpAllocs<'a, 'mir, 'tcx, M> {
766 self.dump_allocs(vec![id])
769 /// Create a lazy debug printer for a list of allocations and all allocations they point to,
772 pub fn dump_allocs<'a>(&'a self, mut allocs: Vec<AllocId>) -> DumpAllocs<'a, 'mir, 'tcx, M> {
775 DumpAllocs { mem: self, allocs }
778 /// Print leaked memory. Allocations reachable from `static_roots` or a `Global` allocation
779 /// are not considered leaked. Leaks whose kind `may_leak()` returns true are not reported.
780 pub fn leak_report(&self, static_roots: &[AllocId]) -> usize {
781 // Collect the set of allocations that are *reachable* from `Global` allocations.
783 let mut reachable = FxHashSet::default();
784 let global_kind = M::GLOBAL_KIND.map(MemoryKind::Machine);
785 let mut todo: Vec<_> = self.alloc_map.filter_map_collect(move |&id, &(kind, _)| {
786 if Some(kind) == global_kind { Some(id) } else { None }
788 todo.extend(static_roots);
789 while let Some(id) = todo.pop() {
790 if reachable.insert(id) {
791 // This is a new allocation, add its relocations to `todo`.
792 if let Some((_, alloc)) = self.alloc_map.get(id) {
793 todo.extend(alloc.relocations().values().map(|tag| tag.get_alloc_id()));
800 // All allocations that are *not* `reachable` and *not* `may_leak` are considered leaking.
801 let leaks: Vec<_> = self.alloc_map.filter_map_collect(|&id, &(kind, _)| {
802 if kind.may_leak() || reachable.contains(&id) { None } else { Some(id) }
806 eprintln!("The following memory was leaked: {:?}", self.dump_allocs(leaks));
811 /// This is used by [priroda](https://github.com/oli-obk/priroda)
812 pub fn alloc_map(&self) -> &M::MemoryMap {
818 /// There's no way to use this directly, it's just a helper struct for the `dump_alloc(s)` methods.
819 pub struct DumpAllocs<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> {
820 mem: &'a Memory<'mir, 'tcx, M>,
821 allocs: Vec<AllocId>,
824 impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> std::fmt::Debug for DumpAllocs<'a, 'mir, 'tcx, M> {
825 fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
826 // Cannot be a closure because it is generic in `Tag`, `Extra`.
827 fn write_allocation_track_relocs<'tcx, Tag: Provenance, Extra>(
828 fmt: &mut std::fmt::Formatter<'_>,
830 allocs_to_print: &mut VecDeque<AllocId>,
831 alloc: &Allocation<Tag, Extra>,
832 ) -> std::fmt::Result {
833 for alloc_id in alloc.relocations().values().map(|tag| tag.get_alloc_id()) {
834 allocs_to_print.push_back(alloc_id);
836 write!(fmt, "{}", display_allocation(tcx, alloc))
839 let mut allocs_to_print: VecDeque<_> = self.allocs.iter().copied().collect();
840 // `allocs_printed` contains all allocations that we have already printed.
841 let mut allocs_printed = FxHashSet::default();
843 while let Some(id) = allocs_to_print.pop_front() {
844 if !allocs_printed.insert(id) {
845 // Already printed, so skip this.
849 write!(fmt, "{}", id)?;
850 match self.mem.alloc_map.get(id) {
851 Some(&(kind, ref alloc)) => {
853 write!(fmt, " ({}, ", kind)?;
854 write_allocation_track_relocs(
857 &mut allocs_to_print,
863 match self.mem.tcx.get_global_alloc(id) {
864 Some(GlobalAlloc::Memory(alloc)) => {
865 write!(fmt, " (unchanged global, ")?;
866 write_allocation_track_relocs(
869 &mut allocs_to_print,
873 Some(GlobalAlloc::Function(func)) => {
874 write!(fmt, " (fn: {})", func)?;
876 Some(GlobalAlloc::Static(did)) => {
877 write!(fmt, " (static: {})", self.mem.tcx.def_path_str(did))?;
880 write!(fmt, " (deallocated)")?;
891 /// Reading and writing.
892 impl<'tcx, 'a, Tag: Provenance, Extra> AllocRefMut<'a, 'tcx, Tag, Extra> {
896 val: ScalarMaybeUninit<Tag>,
897 ) -> InterpResult<'tcx> {
900 .write_scalar(&self.tcx, self.range.subrange(range), val)
901 .map_err(|e| e.to_interp_error(self.alloc_id))?)
904 pub fn write_ptr_sized(
907 val: ScalarMaybeUninit<Tag>,
908 ) -> InterpResult<'tcx> {
909 self.write_scalar(alloc_range(offset, self.tcx.data_layout().pointer_size), val)
913 impl<'tcx, 'a, Tag: Provenance, Extra> AllocRef<'a, 'tcx, Tag, Extra> {
914 pub fn read_scalar(&self, range: AllocRange) -> InterpResult<'tcx, ScalarMaybeUninit<Tag>> {
917 .read_scalar(&self.tcx, self.range.subrange(range))
918 .map_err(|e| e.to_interp_error(self.alloc_id))?)
921 pub fn read_ptr_sized(&self, offset: Size) -> InterpResult<'tcx, ScalarMaybeUninit<Tag>> {
922 self.read_scalar(alloc_range(offset, self.tcx.data_layout().pointer_size))
925 pub fn check_bytes(&self, range: AllocRange, allow_uninit_and_ptr: bool) -> InterpResult<'tcx> {
928 .check_bytes(&self.tcx, self.range.subrange(range), allow_uninit_and_ptr)
929 .map_err(|e| e.to_interp_error(self.alloc_id))?)
933 impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
934 /// Reads the given number of bytes from memory. Returns them as a slice.
936 /// Performs appropriate bounds checks.
939 ptr: Pointer<Option<M::PointerTag>>,
941 ) -> InterpResult<'tcx, &[u8]> {
942 let Some(alloc_ref) = self.get(ptr, size, Align::ONE)? else {
946 // Side-step AllocRef and directly access the underlying bytes more efficiently.
947 // (We are staying inside the bounds here so all is good.)
950 .get_bytes(&alloc_ref.tcx, alloc_ref.range)
951 .map_err(|e| e.to_interp_error(alloc_ref.alloc_id))?)
954 /// Writes the given stream of bytes into memory.
956 /// Performs appropriate bounds checks.
959 ptr: Pointer<Option<M::PointerTag>>,
960 src: impl IntoIterator<Item = u8>,
961 ) -> InterpResult<'tcx> {
962 let mut src = src.into_iter();
963 let (lower, upper) = src.size_hint();
964 let len = upper.expect("can only write bounded iterators");
965 assert_eq!(lower, len, "can only write iterators with a precise length");
967 let size = Size::from_bytes(len);
968 let Some(alloc_ref) = self.get_mut(ptr, size, Align::ONE)? else {
973 "iterator said it was empty but returned an element"
978 // Side-step AllocRef and directly access the underlying bytes more efficiently.
979 // (We are staying inside the bounds here so all is good.)
980 let alloc_id = alloc_ref.alloc_id;
981 let bytes = alloc_ref
983 .get_bytes_mut(&alloc_ref.tcx, alloc_ref.range)
984 .map_err(move |e| e.to_interp_error(alloc_id))?;
985 // `zip` would stop when the first iterator ends; we want to definitely
986 // cover all of `bytes`.
988 *dest = src.next().expect("iterator was shorter than it said it would be");
990 assert_matches!(src.next(), None, "iterator was longer than it said it would be");
996 src: Pointer<Option<M::PointerTag>>,
998 dest: Pointer<Option<M::PointerTag>>,
1001 nonoverlapping: bool,
1002 ) -> InterpResult<'tcx> {
1003 self.copy_repeatedly(src, src_align, dest, dest_align, size, 1, nonoverlapping)
1006 pub fn copy_repeatedly(
1008 src: Pointer<Option<M::PointerTag>>,
1010 dest: Pointer<Option<M::PointerTag>>,
1014 nonoverlapping: bool,
1015 ) -> InterpResult<'tcx> {
1017 // We need to do our own bounds-checks.
1018 let src_parts = self.get_ptr_access(src, size, src_align)?;
1019 let dest_parts = self.get_ptr_access(dest, size * num_copies, dest_align)?; // `Size` multiplication
1021 // FIXME: we look up both allocations twice here, once ebfore for the `check_ptr_access`
1022 // and once below to get the underlying `&[mut] Allocation`.
1024 // Source alloc preparations and access hooks.
1025 let Some((src_alloc_id, src_offset, src)) = src_parts else {
1026 // Zero-sized *source*, that means dst is also zero-sized and we have nothing to do.
1029 let src_alloc = self.get_raw(src_alloc_id)?;
1030 let src_range = alloc_range(src_offset, size);
1031 M::memory_read(&self.extra, &src_alloc.extra, src.provenance, src_range)?;
1032 // We need the `dest` ptr for the next operation, so we get it now.
1033 // We already did the source checks and called the hooks so we are good to return early.
1034 let Some((dest_alloc_id, dest_offset, dest)) = dest_parts else {
1035 // Zero-sized *destination*.
1039 // This checks relocation edges on the src, which needs to happen before
1040 // `prepare_relocation_copy`.
1041 let src_bytes = src_alloc
1042 .get_bytes_with_uninit_and_ptr(&tcx, src_range)
1043 .map_err(|e| e.to_interp_error(src_alloc_id))?
1044 .as_ptr(); // raw ptr, so we can also get a ptr to the destination allocation
1045 // first copy the relocations to a temporary buffer, because
1046 // `get_bytes_mut` will clear the relocations, which is correct,
1047 // since we don't want to keep any relocations at the target.
1049 src_alloc.prepare_relocation_copy(self, src_range, dest_offset, num_copies);
1050 // Prepare a copy of the initialization mask.
1051 let compressed = src_alloc.compress_uninit_range(src_range);
1053 // Destination alloc preparations and access hooks.
1054 let (dest_alloc, extra) = self.get_raw_mut(dest_alloc_id)?;
1055 let dest_range = alloc_range(dest_offset, size * num_copies);
1056 M::memory_written(extra, &mut dest_alloc.extra, dest.provenance, dest_range)?;
1057 let dest_bytes = dest_alloc
1058 .get_bytes_mut_ptr(&tcx, dest_range)
1059 .map_err(|e| e.to_interp_error(dest_alloc_id))?
1062 if compressed.no_bytes_init() {
1063 // Fast path: If all bytes are `uninit` then there is nothing to copy. The target range
1064 // is marked as uninitialized but we otherwise omit changing the byte representation which may
1065 // be arbitrary for uninitialized bytes.
1066 // This also avoids writing to the target bytes so that the backing allocation is never
1067 // touched if the bytes stay uninitialized for the whole interpreter execution. On contemporary
1068 // operating system this can avoid physically allocating the page.
1069 dest_alloc.mark_init(dest_range, false); // `Size` multiplication
1070 dest_alloc.mark_relocation_range(relocations);
1074 // SAFE: The above indexing would have panicked if there weren't at least `size` bytes
1075 // behind `src` and `dest`. Also, we use the overlapping-safe `ptr::copy` if `src` and
1076 // `dest` could possibly overlap.
1077 // The pointers above remain valid even if the `HashMap` table is moved around because they
1078 // point into the `Vec` storing the bytes.
1080 if src_alloc_id == dest_alloc_id {
1083 if (src_offset <= dest_offset && src_offset + size > dest_offset)
1084 || (dest_offset <= src_offset && dest_offset + size > src_offset)
1086 throw_ub_format!("copy_nonoverlapping called on overlapping ranges")
1090 for i in 0..num_copies {
1093 dest_bytes.add((size * i).bytes_usize()), // `Size` multiplication
1098 for i in 0..num_copies {
1099 ptr::copy_nonoverlapping(
1101 dest_bytes.add((size * i).bytes_usize()), // `Size` multiplication
1108 // now fill in all the "init" data
1109 dest_alloc.mark_compressed_init_range(
1111 alloc_range(dest_offset, size), // just a single copy (i.e., not full `dest_range`)
1114 // copy the relocations to the destination
1115 dest_alloc.mark_relocation_range(relocations);
1121 /// Machine pointer introspection.
1122 impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
1123 pub fn scalar_to_ptr(&self, scalar: Scalar<M::PointerTag>) -> Pointer<Option<M::PointerTag>> {
1124 // We use `to_bits_or_ptr_internal` since we are just implementing the method people need to
1125 // call to force getting out a pointer.
1126 match scalar.to_bits_or_ptr_internal(self.pointer_size()) {
1127 Err(ptr) => ptr.into(),
1129 let addr = u64::try_from(bits).unwrap();
1130 let ptr = M::ptr_from_addr(&self, addr);
1132 assert!(ptr.provenance.is_none(), "null pointer can never have an AllocId");
1139 /// Turning a "maybe pointer" into a proper pointer (and some information
1140 /// about where it points), or an absolute address.
1141 pub fn ptr_try_get_alloc(
1143 ptr: Pointer<Option<M::PointerTag>>,
1144 ) -> Result<(AllocId, Size, Pointer<M::PointerTag>), u64> {
1145 match ptr.into_pointer_or_addr() {
1147 let (alloc_id, offset) = M::ptr_get_alloc(self, ptr);
1148 Ok((alloc_id, offset, ptr))
1150 Err(addr) => Err(addr.bytes()),
1154 /// Turning a "maybe pointer" into a proper pointer (and some information about where it points).
1156 pub fn ptr_get_alloc(
1158 ptr: Pointer<Option<M::PointerTag>>,
1159 ) -> InterpResult<'tcx, (AllocId, Size, Pointer<M::PointerTag>)> {
1160 self.ptr_try_get_alloc(ptr).map_err(|offset| {
1161 err_ub!(DanglingIntPointer(offset, CheckInAllocMsg::InboundsTest)).into()