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::ty::{Instance, ParamEnv, TyCtxt};
19 use rustc_target::abi::{Align, HasDataLayout, Size, TargetDataLayout};
22 alloc_range, AllocId, AllocMap, AllocRange, Allocation, CheckInAllocMsg, GlobalAlloc,
23 InterpResult, Machine, MayLeak, Pointer, PointerArithmetic, Provenance, Scalar,
26 use crate::util::pretty;
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 (alloc_kind, mut alloc) = match self.alloc_map.remove(&alloc_id) {
295 Some(alloc) => alloc,
297 // Deallocating global memory -- always an error
298 return Err(match self.tcx.get_global_alloc(alloc_id) {
299 Some(GlobalAlloc::Function(..)) => {
300 err_ub_format!("deallocating {}, which is a function", alloc_id)
302 Some(GlobalAlloc::Static(..) | GlobalAlloc::Memory(..)) => {
303 err_ub_format!("deallocating {}, which is static memory", alloc_id)
305 None => err_ub!(PointerUseAfterFree(alloc_id)),
311 if alloc.mutability == Mutability::Not {
312 throw_ub_format!("deallocating immutable allocation {}", alloc_id);
314 if alloc_kind != kind {
316 "deallocating {}, which is {} memory, using {} deallocation operation",
322 if let Some((size, align)) = old_size_and_align {
323 if size != alloc.size() || align != alloc.align {
325 "incorrect layout on deallocation: {} has size {} and alignment {}, but gave size {} and alignment {}",
327 alloc.size().bytes(),
335 // Let the machine take some extra action
336 let size = alloc.size();
337 M::memory_deallocated(
341 alloc_range(Size::ZERO, size),
344 // Don't forget to remember size and align of this now-dead allocation
345 let old = self.dead_alloc_map.insert(alloc_id, (size, alloc.align));
347 bug!("Nothing can be deallocated twice");
353 /// Internal helper function to determine the allocation and offset of a pointer (if any).
357 ptr: Pointer<Option<M::PointerTag>>,
360 ) -> InterpResult<'tcx, Option<(AllocId, Size, Pointer<M::PointerTag>)>> {
361 let align = M::enforce_alignment(&self.extra).then_some(align);
362 self.check_and_deref_ptr(
366 CheckInAllocMsg::MemoryAccessTest,
367 |alloc_id, offset, ptr| {
369 self.get_size_and_align(alloc_id, AllocCheck::Dereferenceable)?;
370 Ok((size, align, (alloc_id, offset, ptr)))
375 /// Check if the given pointerpoints to live memory of given `size` and `align`
376 /// (ignoring `M::enforce_alignment`). The caller can control the error message for the
377 /// out-of-bounds case.
379 pub fn check_ptr_access_align(
381 ptr: Pointer<Option<M::PointerTag>>,
384 msg: CheckInAllocMsg,
385 ) -> InterpResult<'tcx> {
386 self.check_and_deref_ptr(ptr, size, Some(align), msg, |alloc_id, _, _| {
387 let check = match msg {
388 CheckInAllocMsg::DerefTest | CheckInAllocMsg::MemoryAccessTest => {
389 AllocCheck::Dereferenceable
391 CheckInAllocMsg::PointerArithmeticTest | CheckInAllocMsg::InboundsTest => {
395 let (size, align) = self.get_size_and_align(alloc_id, check)?;
396 Ok((size, align, ()))
401 /// Low-level helper function to check if a ptr is in-bounds and potentially return a reference
402 /// to the allocation it points to. Supports both shared and mutable references, as the actual
403 /// checking is offloaded to a helper closure. `align` defines whether and which alignment check
404 /// is done. Returns `None` for size 0, and otherwise `Some` of what `alloc_size` returned.
405 fn check_and_deref_ptr<T>(
407 ptr: Pointer<Option<M::PointerTag>>,
409 align: Option<Align>,
410 msg: CheckInAllocMsg,
411 alloc_size: impl FnOnce(
414 Pointer<M::PointerTag>,
415 ) -> InterpResult<'tcx, (Size, Align, T)>,
416 ) -> InterpResult<'tcx, Option<T>> {
417 fn check_offset_align(offset: u64, align: Align) -> InterpResult<'static> {
418 if offset % align.bytes() == 0 {
421 // The biggest power of two through which `offset` is divisible.
422 let offset_pow2 = 1 << offset.trailing_zeros();
423 throw_ub!(AlignmentCheckFailed {
424 has: Align::from_bytes(offset_pow2).unwrap(),
430 // Extract from the pointer an `Option<AllocId>` and an offset, which is relative to the
431 // allocation or (if that is `None`) an absolute address.
432 let ptr_or_addr = if size.bytes() == 0 {
433 // Let's see what we can do, but don't throw errors if there's nothing there.
434 self.ptr_try_get_alloc(ptr)
436 // A "real" access, we insist on getting an `AllocId`.
437 Ok(self.ptr_get_alloc(ptr)?)
439 Ok(match ptr_or_addr {
441 // No memory is actually being accessed.
442 debug_assert!(size.bytes() == 0);
445 throw_ub!(DanglingIntPointer(0, msg))
448 if let Some(align) = align {
449 check_offset_align(addr, align)?;
453 Ok((alloc_id, offset, ptr)) => {
454 let (allocation_size, alloc_align, ret_val) = alloc_size(alloc_id, offset, ptr)?;
455 // Test bounds. This also ensures non-null.
456 // It is sufficient to check this for the end pointer. Also check for overflow!
457 if offset.checked_add(size, &self.tcx).map_or(true, |end| end > allocation_size) {
458 throw_ub!(PointerOutOfBounds { alloc_id, offset, size, allocation_size, msg })
460 // Test align. Check this last; if both bounds and alignment are violated
461 // we want the error to be about the bounds.
462 if let Some(align) = align {
463 if M::force_int_for_alignment_check(&self.extra) {
464 let addr = Scalar::from_pointer(ptr, &self.tcx)
465 .to_machine_usize(&self.tcx)
466 .expect("ptr-to-int cast for align check should never fail");
467 check_offset_align(addr, align)?;
469 // Check allocation alignment and offset alignment.
470 if alloc_align.bytes() < align.bytes() {
471 throw_ub!(AlignmentCheckFailed { has: alloc_align, required: align });
473 check_offset_align(offset.bytes(), align)?;
477 // We can still be zero-sized in this branch, in which case we have to
479 if size.bytes() == 0 { None } else { Some(ret_val) }
484 /// Test if the pointer might be null.
485 pub fn ptr_may_be_null(&self, ptr: Pointer<Option<M::PointerTag>>) -> bool {
486 match self.ptr_try_get_alloc(ptr) {
487 Ok((alloc_id, offset, _)) => {
488 let (size, _align) = self
489 .get_size_and_align(alloc_id, AllocCheck::MaybeDead)
490 .expect("alloc info with MaybeDead cannot fail");
491 // If the pointer is out-of-bounds, it may be null.
492 // Note that one-past-the-end (offset == size) is still inbounds, and never null.
495 Err(offset) => offset == 0,
500 /// Allocation accessors
501 impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
502 /// Helper function to obtain a global (tcx) allocation.
503 /// This attempts to return a reference to an existing allocation if
504 /// one can be found in `tcx`. That, however, is only possible if `tcx` and
505 /// this machine use the same pointer tag, so it is indirected through
506 /// `M::tag_allocation`.
511 ) -> InterpResult<'tcx, Cow<'tcx, Allocation<M::PointerTag, M::AllocExtra>>> {
512 let (alloc, def_id) = match self.tcx.get_global_alloc(id) {
513 Some(GlobalAlloc::Memory(mem)) => {
514 // Memory of a constant or promoted or anonymous memory referenced by a static.
517 Some(GlobalAlloc::Function(..)) => throw_ub!(DerefFunctionPointer(id)),
518 None => throw_ub!(PointerUseAfterFree(id)),
519 Some(GlobalAlloc::Static(def_id)) => {
520 assert!(self.tcx.is_static(def_id));
521 assert!(!self.tcx.is_thread_local_static(def_id));
522 // Notice that every static has two `AllocId` that will resolve to the same
523 // thing here: one maps to `GlobalAlloc::Static`, this is the "lazy" ID,
524 // and the other one is maps to `GlobalAlloc::Memory`, this is returned by
525 // `eval_static_initializer` and it is the "resolved" ID.
526 // The resolved ID is never used by the interpreted program, it is hidden.
527 // This is relied upon for soundness of const-patterns; a pointer to the resolved
528 // ID would "sidestep" the checks that make sure consts do not point to statics!
529 // The `GlobalAlloc::Memory` branch here is still reachable though; when a static
530 // contains a reference to memory that was created during its evaluation (i.e., not
531 // to another static), those inner references only exist in "resolved" form.
532 if self.tcx.is_foreign_item(def_id) {
533 throw_unsup!(ReadExternStatic(def_id));
536 (self.tcx.eval_static_initializer(def_id)?, Some(def_id))
539 M::before_access_global(&self.extra, id, alloc, def_id, is_write)?;
540 let alloc = Cow::Borrowed(alloc);
541 // We got tcx memory. Let the machine initialize its "extra" stuff.
542 let alloc = M::init_allocation_extra(
544 id, // always use the ID we got as input, not the "hidden" one.
546 M::GLOBAL_KIND.map(MemoryKind::Machine),
551 /// Gives raw access to the `Allocation`, without bounds or alignment checks.
552 /// The caller is responsible for calling the access hooks!
556 ) -> InterpResult<'tcx, &Allocation<M::PointerTag, M::AllocExtra>> {
557 // The error type of the inner closure here is somewhat funny. We have two
558 // ways of "erroring": An actual error, or because we got a reference from
559 // `get_global_alloc` that we can actually use directly without inserting anything anywhere.
560 // So the error type is `InterpResult<'tcx, &Allocation<M::PointerTag>>`.
561 let a = self.alloc_map.get_or(id, || {
562 let alloc = self.get_global_alloc(id, /*is_write*/ false).map_err(Err)?;
564 Cow::Borrowed(alloc) => {
565 // We got a ref, cheaply return that as an "error" so that the
566 // map does not get mutated.
569 Cow::Owned(alloc) => {
570 // Need to put it into the map and return a ref to that
571 let kind = M::GLOBAL_KIND.expect(
572 "I got a global allocation that I have to copy but the machine does \
573 not expect that to happen",
575 Ok((MemoryKind::Machine(kind), alloc))
579 // Now unpack that funny error type
586 /// "Safe" (bounds and align-checked) allocation access.
589 ptr: Pointer<Option<M::PointerTag>>,
592 ) -> InterpResult<'tcx, Option<AllocRef<'a, 'tcx, M::PointerTag, M::AllocExtra>>> {
593 let align = M::enforce_alignment(&self.extra).then_some(align);
594 let ptr_and_alloc = self.check_and_deref_ptr(
598 CheckInAllocMsg::MemoryAccessTest,
599 |alloc_id, offset, ptr| {
600 let alloc = self.get_raw(alloc_id)?;
601 Ok((alloc.size(), alloc.align, (alloc_id, offset, ptr, alloc)))
604 if let Some((alloc_id, offset, ptr, alloc)) = ptr_and_alloc {
605 let range = alloc_range(offset, size);
606 M::memory_read(&self.extra, &alloc.extra, ptr.provenance, range)?;
607 Ok(Some(AllocRef { alloc, range, tcx: self.tcx, alloc_id }))
609 // Even in this branch we have to be sure that we actually access the allocation, in
610 // order to ensure that `static FOO: Type = FOO;` causes a cycle error instead of
611 // magically pulling *any* ZST value from the ether. However, the `get_raw` above is
612 // always called when `ptr` has an `AllocId`.
617 /// Return the `extra` field of the given allocation.
618 pub fn get_alloc_extra<'a>(&'a self, id: AllocId) -> InterpResult<'tcx, &'a M::AllocExtra> {
619 Ok(&self.get_raw(id)?.extra)
622 /// Gives raw mutable access to the `Allocation`, without bounds or alignment checks.
623 /// The caller is responsible for calling the access hooks!
625 /// Also returns a ptr to `self.extra` so that the caller can use it in parallel with the
630 ) -> InterpResult<'tcx, (&mut Allocation<M::PointerTag, M::AllocExtra>, &mut M::MemoryExtra)>
632 // We have "NLL problem case #3" here, which cannot be worked around without loss of
633 // efficiency even for the common case where the key is in the map.
634 // <https://rust-lang.github.io/rfcs/2094-nll.html#problem-case-3-conditional-control-flow-across-functions>
635 // (Cannot use `get_mut_or` since `get_global_alloc` needs `&self`.)
636 if self.alloc_map.get_mut(id).is_none() {
638 // Allocation not found locally, go look global.
639 let alloc = self.get_global_alloc(id, /*is_write*/ true)?;
640 let kind = M::GLOBAL_KIND.expect(
641 "I got a global allocation that I have to copy but the machine does \
642 not expect that to happen",
644 self.alloc_map.insert(id, (MemoryKind::Machine(kind), alloc.into_owned()));
647 let (_kind, alloc) = self.alloc_map.get_mut(id).unwrap();
648 if alloc.mutability == Mutability::Not {
649 throw_ub!(WriteToReadOnly(id))
651 Ok((alloc, &mut self.extra))
654 /// "Safe" (bounds and align-checked) allocation access.
657 ptr: Pointer<Option<M::PointerTag>>,
660 ) -> InterpResult<'tcx, Option<AllocRefMut<'a, 'tcx, M::PointerTag, M::AllocExtra>>> {
661 let parts = self.get_ptr_access(ptr, size, align)?;
662 if let Some((alloc_id, offset, ptr)) = parts {
664 // FIXME: can we somehow avoid looking up the allocation twice here?
665 // We cannot call `get_raw_mut` inside `check_and_deref_ptr` as that would duplicate `&mut self`.
666 let (alloc, extra) = self.get_raw_mut(alloc_id)?;
667 let range = alloc_range(offset, size);
668 M::memory_written(extra, &mut alloc.extra, ptr.provenance, range)?;
669 Ok(Some(AllocRefMut { alloc, range, tcx, alloc_id }))
675 /// Return the `extra` field of the given allocation.
676 pub fn get_alloc_extra_mut<'a>(
679 ) -> InterpResult<'tcx, (&'a mut M::AllocExtra, &'a mut M::MemoryExtra)> {
680 let (alloc, memory_extra) = self.get_raw_mut(id)?;
681 Ok((&mut alloc.extra, memory_extra))
684 /// Obtain the size and alignment of an allocation, even if that allocation has
685 /// been deallocated.
687 /// If `liveness` is `AllocCheck::MaybeDead`, this function always returns `Ok`.
688 pub fn get_size_and_align(
691 liveness: AllocCheck,
692 ) -> InterpResult<'static, (Size, Align)> {
693 // # Regular allocations
694 // Don't use `self.get_raw` here as that will
695 // a) cause cycles in case `id` refers to a static
696 // b) duplicate a global's allocation in miri
697 if let Some((_, alloc)) = self.alloc_map.get(id) {
698 return Ok((alloc.size(), alloc.align));
701 // # Function pointers
702 // (both global from `alloc_map` and local from `extra_fn_ptr_map`)
703 if self.get_fn_alloc(id).is_some() {
704 return if let AllocCheck::Dereferenceable = liveness {
705 // The caller requested no function pointers.
706 throw_ub!(DerefFunctionPointer(id))
708 Ok((Size::ZERO, Align::ONE))
713 // Can't do this in the match argument, we may get cycle errors since the lock would
714 // be held throughout the match.
715 match self.tcx.get_global_alloc(id) {
716 Some(GlobalAlloc::Static(did)) => {
717 assert!(!self.tcx.is_thread_local_static(did));
718 // Use size and align of the type.
719 let ty = self.tcx.type_of(did);
720 let layout = self.tcx.layout_of(ParamEnv::empty().and(ty)).unwrap();
721 Ok((layout.size, layout.align.abi))
723 Some(GlobalAlloc::Memory(alloc)) => {
724 // Need to duplicate the logic here, because the global allocations have
725 // different associated types than the interpreter-local ones.
726 Ok((alloc.size(), alloc.align))
728 Some(GlobalAlloc::Function(_)) => bug!("We already checked function pointers above"),
729 // The rest must be dead.
731 if let AllocCheck::MaybeDead = liveness {
732 // Deallocated pointers are allowed, we should be able to find
737 .expect("deallocated pointers should all be recorded in `dead_alloc_map`"))
739 throw_ub!(PointerUseAfterFree(id))
745 fn get_fn_alloc(&self, id: AllocId) -> Option<FnVal<'tcx, M::ExtraFnVal>> {
746 if let Some(extra) = self.extra_fn_ptr_map.get(&id) {
747 Some(FnVal::Other(*extra))
749 match self.tcx.get_global_alloc(id) {
750 Some(GlobalAlloc::Function(instance)) => Some(FnVal::Instance(instance)),
758 ptr: Pointer<Option<M::PointerTag>>,
759 ) -> InterpResult<'tcx, FnVal<'tcx, M::ExtraFnVal>> {
760 trace!("get_fn({:?})", ptr);
761 let (alloc_id, offset, _ptr) = self.ptr_get_alloc(ptr)?;
762 if offset.bytes() != 0 {
763 throw_ub!(InvalidFunctionPointer(Pointer::new(alloc_id, offset)))
765 self.get_fn_alloc(alloc_id)
766 .ok_or_else(|| err_ub!(InvalidFunctionPointer(Pointer::new(alloc_id, offset))).into())
769 pub fn mark_immutable(&mut self, id: AllocId) -> InterpResult<'tcx> {
770 self.get_raw_mut(id)?.0.mutability = Mutability::Not;
774 /// Create a lazy debug printer that prints the given allocation and all allocations it points
777 pub fn dump_alloc<'a>(&'a self, id: AllocId) -> DumpAllocs<'a, 'mir, 'tcx, M> {
778 self.dump_allocs(vec![id])
781 /// Create a lazy debug printer for a list of allocations and all allocations they point to,
784 pub fn dump_allocs<'a>(&'a self, mut allocs: Vec<AllocId>) -> DumpAllocs<'a, 'mir, 'tcx, M> {
787 DumpAllocs { mem: self, allocs }
790 /// Print leaked memory. Allocations reachable from `static_roots` or a `Global` allocation
791 /// are not considered leaked. Leaks whose kind `may_leak()` returns true are not reported.
792 pub fn leak_report(&self, static_roots: &[AllocId]) -> usize {
793 // Collect the set of allocations that are *reachable* from `Global` allocations.
795 let mut reachable = FxHashSet::default();
796 let global_kind = M::GLOBAL_KIND.map(MemoryKind::Machine);
797 let mut todo: Vec<_> = self.alloc_map.filter_map_collect(move |&id, &(kind, _)| {
798 if Some(kind) == global_kind { Some(id) } else { None }
800 todo.extend(static_roots);
801 while let Some(id) = todo.pop() {
802 if reachable.insert(id) {
803 // This is a new allocation, add its relocations to `todo`.
804 if let Some((_, alloc)) = self.alloc_map.get(id) {
805 todo.extend(alloc.relocations().values().map(|tag| tag.get_alloc_id()));
812 // All allocations that are *not* `reachable` and *not* `may_leak` are considered leaking.
813 let leaks: Vec<_> = self.alloc_map.filter_map_collect(|&id, &(kind, _)| {
814 if kind.may_leak() || reachable.contains(&id) { None } else { Some(id) }
818 eprintln!("The following memory was leaked: {:?}", self.dump_allocs(leaks));
823 /// This is used by [priroda](https://github.com/oli-obk/priroda)
824 pub fn alloc_map(&self) -> &M::MemoryMap {
830 /// There's no way to use this directly, it's just a helper struct for the `dump_alloc(s)` methods.
831 pub struct DumpAllocs<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> {
832 mem: &'a Memory<'mir, 'tcx, M>,
833 allocs: Vec<AllocId>,
836 impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> std::fmt::Debug for DumpAllocs<'a, 'mir, 'tcx, M> {
837 fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
838 // Cannot be a closure because it is generic in `Tag`, `Extra`.
839 fn write_allocation_track_relocs<'tcx, Tag: Provenance, Extra>(
840 fmt: &mut std::fmt::Formatter<'_>,
842 allocs_to_print: &mut VecDeque<AllocId>,
843 alloc: &Allocation<Tag, Extra>,
844 ) -> std::fmt::Result {
845 for alloc_id in alloc.relocations().values().map(|tag| tag.get_alloc_id()) {
846 allocs_to_print.push_back(alloc_id);
848 write!(fmt, "{}", pretty::display_allocation(tcx, alloc))
851 let mut allocs_to_print: VecDeque<_> = self.allocs.iter().copied().collect();
852 // `allocs_printed` contains all allocations that we have already printed.
853 let mut allocs_printed = FxHashSet::default();
855 while let Some(id) = allocs_to_print.pop_front() {
856 if !allocs_printed.insert(id) {
857 // Already printed, so skip this.
861 write!(fmt, "{}", id)?;
862 match self.mem.alloc_map.get(id) {
863 Some(&(kind, ref alloc)) => {
865 write!(fmt, " ({}, ", kind)?;
866 write_allocation_track_relocs(
869 &mut allocs_to_print,
875 match self.mem.tcx.get_global_alloc(id) {
876 Some(GlobalAlloc::Memory(alloc)) => {
877 write!(fmt, " (unchanged global, ")?;
878 write_allocation_track_relocs(
881 &mut allocs_to_print,
885 Some(GlobalAlloc::Function(func)) => {
886 write!(fmt, " (fn: {})", func)?;
888 Some(GlobalAlloc::Static(did)) => {
889 write!(fmt, " (static: {})", self.mem.tcx.def_path_str(did))?;
892 write!(fmt, " (deallocated)")?;
903 /// Reading and writing.
904 impl<'tcx, 'a, Tag: Copy, Extra> AllocRefMut<'a, 'tcx, Tag, Extra> {
908 val: ScalarMaybeUninit<Tag>,
909 ) -> InterpResult<'tcx> {
912 .write_scalar(&self.tcx, self.range.subrange(range), val)
913 .map_err(|e| e.to_interp_error(self.alloc_id))?)
916 pub fn write_ptr_sized(
919 val: ScalarMaybeUninit<Tag>,
920 ) -> InterpResult<'tcx> {
921 self.write_scalar(alloc_range(offset, self.tcx.data_layout().pointer_size), val)
925 impl<'tcx, 'a, Tag: Copy, Extra> AllocRef<'a, 'tcx, Tag, Extra> {
926 pub fn read_scalar(&self, range: AllocRange) -> InterpResult<'tcx, ScalarMaybeUninit<Tag>> {
929 .read_scalar(&self.tcx, self.range.subrange(range))
930 .map_err(|e| e.to_interp_error(self.alloc_id))?)
933 pub fn read_ptr_sized(&self, offset: Size) -> InterpResult<'tcx, ScalarMaybeUninit<Tag>> {
934 self.read_scalar(alloc_range(offset, self.tcx.data_layout().pointer_size))
937 pub fn check_bytes(&self, range: AllocRange, allow_uninit_and_ptr: bool) -> InterpResult<'tcx> {
940 .check_bytes(&self.tcx, self.range.subrange(range), allow_uninit_and_ptr)
941 .map_err(|e| e.to_interp_error(self.alloc_id))?)
945 impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
946 /// Reads the given number of bytes from memory. Returns them as a slice.
948 /// Performs appropriate bounds checks.
951 ptr: Pointer<Option<M::PointerTag>>,
953 ) -> InterpResult<'tcx, &[u8]> {
954 let alloc_ref = match self.get(ptr, size, Align::ONE)? {
956 None => return Ok(&[]), // zero-sized access
958 // Side-step AllocRef and directly access the underlying bytes more efficiently.
959 // (We are staying inside the bounds here so all is good.)
962 .get_bytes(&alloc_ref.tcx, alloc_ref.range)
963 .map_err(|e| e.to_interp_error(alloc_ref.alloc_id))?)
966 /// Writes the given stream of bytes into memory.
968 /// Performs appropriate bounds checks.
971 ptr: Pointer<Option<M::PointerTag>>,
972 src: impl IntoIterator<Item = u8>,
973 ) -> InterpResult<'tcx> {
974 let mut src = src.into_iter();
975 let (lower, upper) = src.size_hint();
976 let len = upper.expect("can only write bounded iterators");
977 assert_eq!(lower, len, "can only write iterators with a precise length");
979 let size = Size::from_bytes(len);
980 let alloc_ref = match self.get_mut(ptr, size, Align::ONE)? {
981 Some(alloc_ref) => alloc_ref,
987 "iterator said it was empty but returned an element"
993 // Side-step AllocRef and directly access the underlying bytes more efficiently.
994 // (We are staying inside the bounds here so all is good.)
995 let bytes = alloc_ref.alloc.get_bytes_mut(&alloc_ref.tcx, alloc_ref.range);
996 // `zip` would stop when the first iterator ends; we want to definitely
997 // cover all of `bytes`.
999 *dest = src.next().expect("iterator was shorter than it said it would be");
1001 assert_matches!(src.next(), None, "iterator was longer than it said it would be");
1007 src: Pointer<Option<M::PointerTag>>,
1009 dest: Pointer<Option<M::PointerTag>>,
1012 nonoverlapping: bool,
1013 ) -> InterpResult<'tcx> {
1014 self.copy_repeatedly(src, src_align, dest, dest_align, size, 1, nonoverlapping)
1017 pub fn copy_repeatedly(
1019 src: Pointer<Option<M::PointerTag>>,
1021 dest: Pointer<Option<M::PointerTag>>,
1025 nonoverlapping: bool,
1026 ) -> InterpResult<'tcx> {
1028 // We need to do our own bounds-checks.
1029 let src_parts = self.get_ptr_access(src, size, src_align)?;
1030 let dest_parts = self.get_ptr_access(dest, size * num_copies, dest_align)?; // `Size` multiplication
1032 // FIXME: we look up both allocations twice here, once ebfore for the `check_ptr_access`
1033 // and once below to get the underlying `&[mut] Allocation`.
1035 // Source alloc preparations and access hooks.
1036 let (src_alloc_id, src_offset, src) = match src_parts {
1037 None => return Ok(()), // Zero-sized *source*, that means dst is also zero-sized and we have nothing to do.
1038 Some(src_ptr) => src_ptr,
1040 let src_alloc = self.get_raw(src_alloc_id)?;
1041 let src_range = alloc_range(src_offset, size);
1042 M::memory_read(&self.extra, &src_alloc.extra, src.provenance, src_range)?;
1043 // We need the `dest` ptr for the next operation, so we get it now.
1044 // We already did the source checks and called the hooks so we are good to return early.
1045 let (dest_alloc_id, dest_offset, dest) = match dest_parts {
1046 None => return Ok(()), // Zero-sized *destiantion*.
1047 Some(dest_ptr) => dest_ptr,
1050 // first copy the relocations to a temporary buffer, because
1051 // `get_bytes_mut` will clear the relocations, which is correct,
1052 // since we don't want to keep any relocations at the target.
1053 // (`get_bytes_with_uninit_and_ptr` below checks that there are no
1054 // relocations overlapping the edges; those would not be handled correctly).
1056 src_alloc.prepare_relocation_copy(self, src_range, dest_offset, num_copies);
1057 // Prepare a copy of the initialization mask.
1058 let compressed = src_alloc.compress_uninit_range(src_range);
1059 // This checks relocation edges on the src.
1060 let src_bytes = src_alloc
1061 .get_bytes_with_uninit_and_ptr(&tcx, src_range)
1062 .map_err(|e| e.to_interp_error(src_alloc_id))?
1063 .as_ptr(); // raw ptr, so we can also get a ptr to the destination allocation
1065 // Destination alloc preparations and access hooks.
1066 let (dest_alloc, extra) = self.get_raw_mut(dest_alloc_id)?;
1067 let dest_range = alloc_range(dest_offset, size * num_copies);
1068 M::memory_written(extra, &mut dest_alloc.extra, dest.provenance, dest_range)?;
1069 let dest_bytes = dest_alloc.get_bytes_mut_ptr(&tcx, dest_range).as_mut_ptr();
1071 if compressed.no_bytes_init() {
1072 // Fast path: If all bytes are `uninit` then there is nothing to copy. The target range
1073 // is marked as uninitialized but we otherwise omit changing the byte representation which may
1074 // be arbitrary for uninitialized bytes.
1075 // This also avoids writing to the target bytes so that the backing allocation is never
1076 // touched if the bytes stay uninitialized for the whole interpreter execution. On contemporary
1077 // operating system this can avoid physically allocating the page.
1078 dest_alloc.mark_init(dest_range, false); // `Size` multiplication
1079 dest_alloc.mark_relocation_range(relocations);
1083 // SAFE: The above indexing would have panicked if there weren't at least `size` bytes
1084 // behind `src` and `dest`. Also, we use the overlapping-safe `ptr::copy` if `src` and
1085 // `dest` could possibly overlap.
1086 // The pointers above remain valid even if the `HashMap` table is moved around because they
1087 // point into the `Vec` storing the bytes.
1089 if src_alloc_id == dest_alloc_id {
1092 if (src_offset <= dest_offset && src_offset + size > dest_offset)
1093 || (dest_offset <= src_offset && dest_offset + size > src_offset)
1095 throw_ub_format!("copy_nonoverlapping called on overlapping ranges")
1099 for i in 0..num_copies {
1102 dest_bytes.add((size * i).bytes_usize()), // `Size` multiplication
1107 for i in 0..num_copies {
1108 ptr::copy_nonoverlapping(
1110 dest_bytes.add((size * i).bytes_usize()), // `Size` multiplication
1117 // now fill in all the "init" data
1118 dest_alloc.mark_compressed_init_range(
1120 alloc_range(dest_offset, size), // just a single copy (i.e., not full `dest_range`)
1123 // copy the relocations to the destination
1124 dest_alloc.mark_relocation_range(relocations);
1130 /// Machine pointer introspection.
1131 impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
1132 pub fn scalar_to_ptr(&self, scalar: Scalar<M::PointerTag>) -> Pointer<Option<M::PointerTag>> {
1133 // We use `to_bits_or_ptr_internal` since we are just implementing the method people need to
1134 // call to force getting out a pointer.
1135 match scalar.to_bits_or_ptr_internal(self.pointer_size()) {
1136 Err(ptr) => ptr.into(),
1138 let addr = u64::try_from(bits).unwrap();
1139 M::ptr_from_addr(&self, addr)
1144 /// Turning a "maybe pointer" into a proper pointer (and some information
1145 /// about where it points), or an absolute address.
1146 pub fn ptr_try_get_alloc(
1148 ptr: Pointer<Option<M::PointerTag>>,
1149 ) -> Result<(AllocId, Size, Pointer<M::PointerTag>), u64> {
1150 match ptr.into_pointer_or_addr() {
1152 let (alloc_id, offset) = M::ptr_get_alloc(self, ptr);
1153 Ok((alloc_id, offset, ptr))
1155 Err(addr) => Err(addr.bytes()),
1159 /// Turning a "maybe pointer" into a proper pointer (and some information about where it points).
1161 pub fn ptr_get_alloc(
1163 ptr: Pointer<Option<M::PointerTag>>,
1164 ) -> InterpResult<'tcx, (AllocId, Size, Pointer<M::PointerTag>)> {
1165 self.ptr_try_get_alloc(ptr).map_err(|offset| {
1166 err_ub!(DanglingIntPointer(offset, CheckInAllocMsg::InboundsTest)).into()