| //! The memory subsystem. |
| //! |
| //! Generally, we use `Pointer` to denote memory addresses. However, some operations |
| //! have a "size"-like parameter, and they take `Scalar` for the address because |
| //! if the size is 0, then the pointer can also be a (properly aligned, non-null) |
| //! integer. It is crucial that these operations call `check_align` *before* |
| //! short-circuiting the empty case! |
| |
| use std::assert_matches::assert_matches; |
| use std::borrow::Cow; |
| use std::cell::Cell; |
| use std::collections::VecDeque; |
| use std::{fmt, ptr}; |
| |
| use rustc_ast::Mutability; |
| use rustc_data_structures::fx::{FxHashSet, FxIndexMap}; |
| use rustc_hir::def::DefKind; |
| use rustc_middle::bug; |
| use rustc_middle::mir::display_allocation; |
| use rustc_middle::ty::{self, Instance, ParamEnv, Ty, TyCtxt}; |
| use rustc_target::abi::{Align, HasDataLayout, Size}; |
| use tracing::{debug, instrument, trace}; |
| |
| use super::{ |
| alloc_range, err_ub, err_ub_custom, throw_ub, throw_ub_custom, throw_unsup, throw_unsup_format, |
| AllocBytes, AllocId, AllocMap, AllocRange, Allocation, CheckAlignMsg, CheckInAllocMsg, |
| CtfeProvenance, GlobalAlloc, InterpCx, InterpResult, Machine, MayLeak, Misalignment, Pointer, |
| PointerArithmetic, Provenance, Scalar, |
| }; |
| use crate::fluent_generated as fluent; |
| |
| #[derive(Debug, PartialEq, Copy, Clone)] |
| pub enum MemoryKind<T> { |
| /// Stack memory. Error if deallocated except during a stack pop. |
| Stack, |
| /// Memory allocated by `caller_location` intrinsic. Error if ever deallocated. |
| CallerLocation, |
| /// Additional memory kinds a machine wishes to distinguish from the builtin ones. |
| Machine(T), |
| } |
| |
| impl<T: MayLeak> MayLeak for MemoryKind<T> { |
| #[inline] |
| fn may_leak(self) -> bool { |
| match self { |
| MemoryKind::Stack => false, |
| MemoryKind::CallerLocation => true, |
| MemoryKind::Machine(k) => k.may_leak(), |
| } |
| } |
| } |
| |
| impl<T: fmt::Display> fmt::Display for MemoryKind<T> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| match self { |
| MemoryKind::Stack => write!(f, "stack variable"), |
| MemoryKind::CallerLocation => write!(f, "caller location"), |
| MemoryKind::Machine(m) => write!(f, "{m}"), |
| } |
| } |
| } |
| |
| /// The return value of `get_alloc_info` indicates the "kind" of the allocation. |
| #[derive(Copy, Clone, PartialEq, Debug)] |
| pub enum AllocKind { |
| /// A regular live data allocation. |
| LiveData, |
| /// A function allocation (that fn ptrs point to). |
| Function, |
| /// A (symbolic) vtable allocation. |
| VTable, |
| /// A dead allocation. |
| Dead, |
| } |
| |
| /// The value of a function pointer. |
| #[derive(Debug, Copy, Clone)] |
| pub enum FnVal<'tcx, Other> { |
| Instance(Instance<'tcx>), |
| Other(Other), |
| } |
| |
| impl<'tcx, Other> FnVal<'tcx, Other> { |
| pub fn as_instance(self) -> InterpResult<'tcx, Instance<'tcx>> { |
| match self { |
| FnVal::Instance(instance) => Ok(instance), |
| FnVal::Other(_) => { |
| throw_unsup_format!("'foreign' function pointers are not supported in this context") |
| } |
| } |
| } |
| } |
| |
| // `Memory` has to depend on the `Machine` because some of its operations |
| // (e.g., `get`) call a `Machine` hook. |
| pub struct Memory<'tcx, M: Machine<'tcx>> { |
| /// Allocations local to this instance of the interpreter. The kind |
| /// helps ensure that the same mechanism is used for allocation and |
| /// deallocation. When an allocation is not found here, it is a |
| /// global and looked up in the `tcx` for read access. Some machines may |
| /// have to mutate this map even on a read-only access to a global (because |
| /// they do pointer provenance tracking and the allocations in `tcx` have |
| /// the wrong type), so we let the machine override this type. |
| /// Either way, if the machine allows writing to a global, doing so will |
| /// create a copy of the global allocation here. |
| // FIXME: this should not be public, but interning currently needs access to it |
| pub(super) alloc_map: M::MemoryMap, |
| |
| /// Map for "extra" function pointers. |
| extra_fn_ptr_map: FxIndexMap<AllocId, M::ExtraFnVal>, |
| |
| /// To be able to compare pointers with null, and to check alignment for accesses |
| /// to ZSTs (where pointers may dangle), we keep track of the size even for allocations |
| /// that do not exist any more. |
| // FIXME: this should not be public, but interning currently needs access to it |
| pub(super) dead_alloc_map: FxIndexMap<AllocId, (Size, Align)>, |
| |
| /// This stores whether we are currently doing reads purely for the purpose of validation. |
| /// Those reads do not trigger the machine's hooks for memory reads. |
| /// Needless to say, this must only be set with great care! |
| validation_in_progress: Cell<bool>, |
| } |
| |
| /// A reference to some allocation that was already bounds-checked for the given region |
| /// and had the on-access machine hooks run. |
| #[derive(Copy, Clone)] |
| pub struct AllocRef<'a, 'tcx, Prov: Provenance, Extra, Bytes: AllocBytes = Box<[u8]>> { |
| alloc: &'a Allocation<Prov, Extra, Bytes>, |
| range: AllocRange, |
| tcx: TyCtxt<'tcx>, |
| alloc_id: AllocId, |
| } |
| /// A reference to some allocation that was already bounds-checked for the given region |
| /// and had the on-access machine hooks run. |
| pub struct AllocRefMut<'a, 'tcx, Prov: Provenance, Extra, Bytes: AllocBytes = Box<[u8]>> { |
| alloc: &'a mut Allocation<Prov, Extra, Bytes>, |
| range: AllocRange, |
| tcx: TyCtxt<'tcx>, |
| alloc_id: AllocId, |
| } |
| |
| impl<'tcx, M: Machine<'tcx>> Memory<'tcx, M> { |
| pub fn new() -> Self { |
| Memory { |
| alloc_map: M::MemoryMap::default(), |
| extra_fn_ptr_map: FxIndexMap::default(), |
| dead_alloc_map: FxIndexMap::default(), |
| validation_in_progress: Cell::new(false), |
| } |
| } |
| |
| /// This is used by [priroda](https://github.com/oli-obk/priroda) |
| pub fn alloc_map(&self) -> &M::MemoryMap { |
| &self.alloc_map |
| } |
| } |
| |
| impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { |
| /// Call this to turn untagged "global" pointers (obtained via `tcx`) into |
| /// the machine pointer to the allocation. Must never be used |
| /// for any other pointers, nor for TLS statics. |
| /// |
| /// Using the resulting pointer represents a *direct* access to that memory |
| /// (e.g. by directly using a `static`), |
| /// as opposed to access through a pointer that was created by the program. |
| /// |
| /// This function can fail only if `ptr` points to an `extern static`. |
| #[inline] |
| pub fn global_root_pointer( |
| &self, |
| ptr: Pointer<CtfeProvenance>, |
| ) -> InterpResult<'tcx, Pointer<M::Provenance>> { |
| let alloc_id = ptr.provenance.alloc_id(); |
| // We need to handle `extern static`. |
| match self.tcx.try_get_global_alloc(alloc_id) { |
| Some(GlobalAlloc::Static(def_id)) if self.tcx.is_thread_local_static(def_id) => { |
| // Thread-local statics do not have a constant address. They *must* be accessed via |
| // `ThreadLocalRef`; we can never have a pointer to them as a regular constant value. |
| bug!("global memory cannot point to thread-local static") |
| } |
| Some(GlobalAlloc::Static(def_id)) if self.tcx.is_foreign_item(def_id) => { |
| return M::extern_static_pointer(self, def_id); |
| } |
| None => { |
| assert!( |
| self.memory.extra_fn_ptr_map.contains_key(&alloc_id), |
| "{alloc_id:?} is neither global nor a function pointer" |
| ); |
| } |
| _ => {} |
| } |
| // And we need to get the provenance. |
| M::adjust_alloc_root_pointer(self, ptr, M::GLOBAL_KIND.map(MemoryKind::Machine)) |
| } |
| |
| pub fn fn_ptr(&mut self, fn_val: FnVal<'tcx, M::ExtraFnVal>) -> Pointer<M::Provenance> { |
| let id = match fn_val { |
| FnVal::Instance(instance) => self.tcx.reserve_and_set_fn_alloc(instance), |
| FnVal::Other(extra) => { |
| // FIXME(RalfJung): Should we have a cache here? |
| let id = self.tcx.reserve_alloc_id(); |
| let old = self.memory.extra_fn_ptr_map.insert(id, extra); |
| assert!(old.is_none()); |
| id |
| } |
| }; |
| // Functions are global allocations, so make sure we get the right root pointer. |
| // We know this is not an `extern static` so this cannot fail. |
| self.global_root_pointer(Pointer::from(id)).unwrap() |
| } |
| |
| pub fn allocate_ptr( |
| &mut self, |
| size: Size, |
| align: Align, |
| kind: MemoryKind<M::MemoryKind>, |
| ) -> InterpResult<'tcx, Pointer<M::Provenance>> { |
| let alloc = if M::PANIC_ON_ALLOC_FAIL { |
| Allocation::uninit(size, align) |
| } else { |
| Allocation::try_uninit(size, align)? |
| }; |
| self.allocate_raw_ptr(alloc, kind) |
| } |
| |
| pub fn allocate_bytes_ptr( |
| &mut self, |
| bytes: &[u8], |
| align: Align, |
| kind: MemoryKind<M::MemoryKind>, |
| mutability: Mutability, |
| ) -> InterpResult<'tcx, Pointer<M::Provenance>> { |
| let alloc = Allocation::from_bytes(bytes, align, mutability); |
| self.allocate_raw_ptr(alloc, kind) |
| } |
| |
| pub fn allocate_raw_ptr( |
| &mut self, |
| alloc: Allocation<M::Provenance, (), M::Bytes>, |
| kind: MemoryKind<M::MemoryKind>, |
| ) -> InterpResult<'tcx, Pointer<M::Provenance>> { |
| let id = self.tcx.reserve_alloc_id(); |
| debug_assert_ne!( |
| Some(kind), |
| M::GLOBAL_KIND.map(MemoryKind::Machine), |
| "dynamically allocating global memory" |
| ); |
| // We have set things up so we don't need to call `adjust_from_tcx` here, |
| // so we avoid copying the entire allocation contents. |
| let extra = M::init_alloc_extra(self, id, kind, alloc.size(), alloc.align)?; |
| let alloc = alloc.with_extra(extra); |
| self.memory.alloc_map.insert(id, (kind, alloc)); |
| M::adjust_alloc_root_pointer(self, Pointer::from(id), Some(kind)) |
| } |
| |
| pub fn reallocate_ptr( |
| &mut self, |
| ptr: Pointer<Option<M::Provenance>>, |
| old_size_and_align: Option<(Size, Align)>, |
| new_size: Size, |
| new_align: Align, |
| kind: MemoryKind<M::MemoryKind>, |
| ) -> InterpResult<'tcx, Pointer<M::Provenance>> { |
| let (alloc_id, offset, _prov) = self.ptr_get_alloc_id(ptr, 0)?; |
| if offset.bytes() != 0 { |
| throw_ub_custom!( |
| fluent::const_eval_realloc_or_alloc_with_offset, |
| ptr = format!("{ptr:?}"), |
| kind = "realloc" |
| ); |
| } |
| |
| // For simplicities' sake, we implement reallocate as "alloc, copy, dealloc". |
| // This happens so rarely, the perf advantage is outweighed by the maintenance cost. |
| let new_ptr = self.allocate_ptr(new_size, new_align, kind)?; |
| let old_size = match old_size_and_align { |
| Some((size, _align)) => size, |
| None => self.get_alloc_raw(alloc_id)?.size(), |
| }; |
| // This will also call the access hooks. |
| self.mem_copy(ptr, new_ptr.into(), old_size.min(new_size), /*nonoverlapping*/ true)?; |
| self.deallocate_ptr(ptr, old_size_and_align, kind)?; |
| |
| Ok(new_ptr) |
| } |
| |
| #[instrument(skip(self), level = "debug")] |
| pub fn deallocate_ptr( |
| &mut self, |
| ptr: Pointer<Option<M::Provenance>>, |
| old_size_and_align: Option<(Size, Align)>, |
| kind: MemoryKind<M::MemoryKind>, |
| ) -> InterpResult<'tcx> { |
| let (alloc_id, offset, prov) = self.ptr_get_alloc_id(ptr, 0)?; |
| trace!("deallocating: {alloc_id:?}"); |
| |
| if offset.bytes() != 0 { |
| throw_ub_custom!( |
| fluent::const_eval_realloc_or_alloc_with_offset, |
| ptr = format!("{ptr:?}"), |
| kind = "dealloc", |
| ); |
| } |
| |
| let Some((alloc_kind, mut alloc)) = self.memory.alloc_map.remove(&alloc_id) else { |
| // Deallocating global memory -- always an error |
| return Err(match self.tcx.try_get_global_alloc(alloc_id) { |
| Some(GlobalAlloc::Function { .. }) => { |
| err_ub_custom!( |
| fluent::const_eval_invalid_dealloc, |
| alloc_id = alloc_id, |
| kind = "fn", |
| ) |
| } |
| Some(GlobalAlloc::VTable(..)) => { |
| err_ub_custom!( |
| fluent::const_eval_invalid_dealloc, |
| alloc_id = alloc_id, |
| kind = "vtable", |
| ) |
| } |
| Some(GlobalAlloc::Static(..) | GlobalAlloc::Memory(..)) => { |
| err_ub_custom!( |
| fluent::const_eval_invalid_dealloc, |
| alloc_id = alloc_id, |
| kind = "static_mem" |
| ) |
| } |
| None => err_ub!(PointerUseAfterFree(alloc_id, CheckInAllocMsg::MemoryAccessTest)), |
| } |
| .into()); |
| }; |
| |
| if alloc.mutability.is_not() { |
| throw_ub_custom!(fluent::const_eval_dealloc_immutable, alloc = alloc_id,); |
| } |
| if alloc_kind != kind { |
| throw_ub_custom!( |
| fluent::const_eval_dealloc_kind_mismatch, |
| alloc = alloc_id, |
| alloc_kind = format!("{alloc_kind}"), |
| kind = format!("{kind}"), |
| ); |
| } |
| if let Some((size, align)) = old_size_and_align { |
| if size != alloc.size() || align != alloc.align { |
| throw_ub_custom!( |
| fluent::const_eval_dealloc_incorrect_layout, |
| alloc = alloc_id, |
| size = alloc.size().bytes(), |
| align = alloc.align.bytes(), |
| size_found = size.bytes(), |
| align_found = align.bytes(), |
| ) |
| } |
| } |
| |
| // Let the machine take some extra action |
| let size = alloc.size(); |
| M::before_memory_deallocation( |
| self.tcx, |
| &mut self.machine, |
| &mut alloc.extra, |
| (alloc_id, prov), |
| size, |
| alloc.align, |
| kind, |
| )?; |
| |
| // Don't forget to remember size and align of this now-dead allocation |
| let old = self.memory.dead_alloc_map.insert(alloc_id, (size, alloc.align)); |
| if old.is_some() { |
| bug!("Nothing can be deallocated twice"); |
| } |
| |
| Ok(()) |
| } |
| |
| /// Internal helper function to determine the allocation and offset of a pointer (if any). |
| #[inline(always)] |
| fn get_ptr_access( |
| &self, |
| ptr: Pointer<Option<M::Provenance>>, |
| size: Size, |
| ) -> InterpResult<'tcx, Option<(AllocId, Size, M::ProvenanceExtra)>> { |
| let size = i64::try_from(size.bytes()).unwrap(); // it would be an error to even ask for more than isize::MAX bytes |
| self.check_and_deref_ptr( |
| ptr, |
| size, |
| CheckInAllocMsg::MemoryAccessTest, |
| |alloc_id, offset, prov| { |
| let (size, align) = self |
| .get_live_alloc_size_and_align(alloc_id, CheckInAllocMsg::MemoryAccessTest)?; |
| Ok((size, align, (alloc_id, offset, prov))) |
| }, |
| ) |
| } |
| |
| /// Check if the given pointer points to live memory of the given `size`. |
| /// The caller can control the error message for the out-of-bounds case. |
| #[inline(always)] |
| pub fn check_ptr_access( |
| &self, |
| ptr: Pointer<Option<M::Provenance>>, |
| size: Size, |
| msg: CheckInAllocMsg, |
| ) -> InterpResult<'tcx> { |
| let size = i64::try_from(size.bytes()).unwrap(); // it would be an error to even ask for more than isize::MAX bytes |
| self.check_and_deref_ptr(ptr, size, msg, |alloc_id, _, _| { |
| let (size, align) = self.get_live_alloc_size_and_align(alloc_id, msg)?; |
| Ok((size, align, ())) |
| })?; |
| Ok(()) |
| } |
| |
| /// Check whether the given pointer points to live memory for a signed amount of bytes. |
| /// A negative amounts means that the given range of memory to the left of the pointer |
| /// needs to be dereferenceable. |
| pub fn check_ptr_access_signed( |
| &self, |
| ptr: Pointer<Option<M::Provenance>>, |
| size: i64, |
| msg: CheckInAllocMsg, |
| ) -> InterpResult<'tcx> { |
| self.check_and_deref_ptr(ptr, size, msg, |alloc_id, _, _| { |
| let (size, align) = self.get_live_alloc_size_and_align(alloc_id, msg)?; |
| Ok((size, align, ())) |
| })?; |
| Ok(()) |
| } |
| |
| /// Low-level helper function to check if a ptr is in-bounds and potentially return a reference |
| /// to the allocation it points to. Supports both shared and mutable references, as the actual |
| /// checking is offloaded to a helper closure. Supports signed sizes for checks "to the left" of |
| /// a pointer. |
| /// |
| /// `alloc_size` will only get called for non-zero-sized accesses. |
| /// |
| /// Returns `None` if and only if the size is 0. |
| fn check_and_deref_ptr<T>( |
| &self, |
| ptr: Pointer<Option<M::Provenance>>, |
| size: i64, |
| msg: CheckInAllocMsg, |
| alloc_size: impl FnOnce( |
| AllocId, |
| Size, |
| M::ProvenanceExtra, |
| ) -> InterpResult<'tcx, (Size, Align, T)>, |
| ) -> InterpResult<'tcx, Option<T>> { |
| // Everything is okay with size 0. |
| if size == 0 { |
| return Ok(None); |
| } |
| |
| Ok(match self.ptr_try_get_alloc_id(ptr, size) { |
| Err(addr) => { |
| // We couldn't get a proper allocation. |
| throw_ub!(DanglingIntPointer { addr, inbounds_size: size, msg }); |
| } |
| Ok((alloc_id, offset, prov)) => { |
| let (alloc_size, _alloc_align, ret_val) = alloc_size(alloc_id, offset, prov)?; |
| let offset = offset.bytes(); |
| // Compute absolute begin and end of the range. |
| let (begin, end) = if size >= 0 { |
| (Some(offset), offset.checked_add(size as u64)) |
| } else { |
| (offset.checked_sub(size.unsigned_abs()), Some(offset)) |
| }; |
| // Ensure both are within bounds. |
| let in_bounds = begin.is_some() && end.is_some_and(|e| e <= alloc_size.bytes()); |
| if !in_bounds { |
| throw_ub!(PointerOutOfBounds { |
| alloc_id, |
| alloc_size, |
| ptr_offset: self.target_usize_to_isize(offset), |
| inbounds_size: size, |
| msg, |
| }) |
| } |
| |
| Some(ret_val) |
| } |
| }) |
| } |
| |
| pub(super) fn check_misalign( |
| &self, |
| misaligned: Option<Misalignment>, |
| msg: CheckAlignMsg, |
| ) -> InterpResult<'tcx> { |
| if let Some(misaligned) = misaligned { |
| throw_ub!(AlignmentCheckFailed(misaligned, msg)) |
| } |
| Ok(()) |
| } |
| |
| pub(super) fn is_ptr_misaligned( |
| &self, |
| ptr: Pointer<Option<M::Provenance>>, |
| align: Align, |
| ) -> Option<Misalignment> { |
| if !M::enforce_alignment(self) || align.bytes() == 1 { |
| return None; |
| } |
| |
| #[inline] |
| fn is_offset_misaligned(offset: u64, align: Align) -> Option<Misalignment> { |
| if offset % align.bytes() == 0 { |
| None |
| } else { |
| // The biggest power of two through which `offset` is divisible. |
| let offset_pow2 = 1 << offset.trailing_zeros(); |
| Some(Misalignment { has: Align::from_bytes(offset_pow2).unwrap(), required: align }) |
| } |
| } |
| |
| match self.ptr_try_get_alloc_id(ptr, 0) { |
| Err(addr) => is_offset_misaligned(addr, align), |
| Ok((alloc_id, offset, _prov)) => { |
| let (_size, alloc_align, kind) = self.get_alloc_info(alloc_id); |
| if let Some(misalign) = |
| M::alignment_check(self, alloc_id, alloc_align, kind, offset, align) |
| { |
| Some(misalign) |
| } else if M::Provenance::OFFSET_IS_ADDR { |
| is_offset_misaligned(ptr.addr().bytes(), align) |
| } else { |
| // Check allocation alignment and offset alignment. |
| if alloc_align.bytes() < align.bytes() { |
| Some(Misalignment { has: alloc_align, required: align }) |
| } else { |
| is_offset_misaligned(offset.bytes(), align) |
| } |
| } |
| } |
| } |
| } |
| |
| /// Checks a pointer for misalignment. |
| /// |
| /// The error assumes this is checking the pointer used directly for an access. |
| pub fn check_ptr_align( |
| &self, |
| ptr: Pointer<Option<M::Provenance>>, |
| align: Align, |
| ) -> InterpResult<'tcx> { |
| self.check_misalign(self.is_ptr_misaligned(ptr, align), CheckAlignMsg::AccessedPtr) |
| } |
| } |
| |
| impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { |
| /// This function is used by Miri's provenance GC to remove unreachable entries from the dead_alloc_map. |
| pub fn remove_unreachable_allocs(&mut self, reachable_allocs: &FxHashSet<AllocId>) { |
| // Unlike all the other GC helpers where we check if an `AllocId` is found in the interpreter or |
| // is live, here all the IDs in the map are for dead allocations so we don't |
| // need to check for liveness. |
| #[allow(rustc::potential_query_instability)] // Only used from Miri, not queries. |
| self.memory.dead_alloc_map.retain(|id, _| reachable_allocs.contains(id)); |
| } |
| } |
| |
| /// Allocation accessors |
| impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { |
| /// Helper function to obtain a global (tcx) allocation. |
| /// This attempts to return a reference to an existing allocation if |
| /// one can be found in `tcx`. That, however, is only possible if `tcx` and |
| /// this machine use the same pointer provenance, so it is indirected through |
| /// `M::adjust_allocation`. |
| fn get_global_alloc( |
| &self, |
| id: AllocId, |
| is_write: bool, |
| ) -> InterpResult<'tcx, Cow<'tcx, Allocation<M::Provenance, M::AllocExtra, M::Bytes>>> { |
| let (alloc, def_id) = match self.tcx.try_get_global_alloc(id) { |
| Some(GlobalAlloc::Memory(mem)) => { |
| // Memory of a constant or promoted or anonymous memory referenced by a static. |
| (mem, None) |
| } |
| Some(GlobalAlloc::Function { .. }) => throw_ub!(DerefFunctionPointer(id)), |
| Some(GlobalAlloc::VTable(..)) => throw_ub!(DerefVTablePointer(id)), |
| None => throw_ub!(PointerUseAfterFree(id, CheckInAllocMsg::MemoryAccessTest)), |
| Some(GlobalAlloc::Static(def_id)) => { |
| assert!(self.tcx.is_static(def_id)); |
| // Thread-local statics do not have a constant address. They *must* be accessed via |
| // `ThreadLocalRef`; we can never have a pointer to them as a regular constant value. |
| assert!(!self.tcx.is_thread_local_static(def_id)); |
| // Notice that every static has two `AllocId` that will resolve to the same |
| // thing here: one maps to `GlobalAlloc::Static`, this is the "lazy" ID, |
| // and the other one is maps to `GlobalAlloc::Memory`, this is returned by |
| // `eval_static_initializer` and it is the "resolved" ID. |
| // The resolved ID is never used by the interpreted program, it is hidden. |
| // This is relied upon for soundness of const-patterns; a pointer to the resolved |
| // ID would "sidestep" the checks that make sure consts do not point to statics! |
| // The `GlobalAlloc::Memory` branch here is still reachable though; when a static |
| // contains a reference to memory that was created during its evaluation (i.e., not |
| // to another static), those inner references only exist in "resolved" form. |
| if self.tcx.is_foreign_item(def_id) { |
| // This is unreachable in Miri, but can happen in CTFE where we actually *do* support |
| // referencing arbitrary (declared) extern statics. |
| throw_unsup!(ExternStatic(def_id)); |
| } |
| |
| // We don't give a span -- statics don't need that, they cannot be generic or associated. |
| let val = self.ctfe_query(|tcx| tcx.eval_static_initializer(def_id))?; |
| (val, Some(def_id)) |
| } |
| }; |
| M::before_access_global(self.tcx, &self.machine, id, alloc, def_id, is_write)?; |
| // We got tcx memory. Let the machine initialize its "extra" stuff. |
| M::adjust_global_allocation( |
| self, |
| id, // always use the ID we got as input, not the "hidden" one. |
| alloc.inner(), |
| ) |
| } |
| |
| /// Gives raw access to the `Allocation`, without bounds or alignment checks. |
| /// The caller is responsible for calling the access hooks! |
| /// |
| /// You almost certainly want to use `get_ptr_alloc`/`get_ptr_alloc_mut` instead. |
| fn get_alloc_raw( |
| &self, |
| id: AllocId, |
| ) -> InterpResult<'tcx, &Allocation<M::Provenance, M::AllocExtra, M::Bytes>> { |
| // The error type of the inner closure here is somewhat funny. We have two |
| // ways of "erroring": An actual error, or because we got a reference from |
| // `get_global_alloc` that we can actually use directly without inserting anything anywhere. |
| // So the error type is `InterpResult<'tcx, &Allocation<M::Provenance>>`. |
| let a = self.memory.alloc_map.get_or(id, || { |
| let alloc = self.get_global_alloc(id, /*is_write*/ false).map_err(Err)?; |
| match alloc { |
| Cow::Borrowed(alloc) => { |
| // We got a ref, cheaply return that as an "error" so that the |
| // map does not get mutated. |
| Err(Ok(alloc)) |
| } |
| Cow::Owned(alloc) => { |
| // Need to put it into the map and return a ref to that |
| let kind = M::GLOBAL_KIND.expect( |
| "I got a global allocation that I have to copy but the machine does \ |
| not expect that to happen", |
| ); |
| Ok((MemoryKind::Machine(kind), alloc)) |
| } |
| } |
| }); |
| // Now unpack that funny error type |
| match a { |
| Ok(a) => Ok(&a.1), |
| Err(a) => a, |
| } |
| } |
| |
| /// Gives raw, immutable access to the `Allocation` address, without bounds or alignment checks. |
| /// The caller is responsible for calling the access hooks! |
| pub fn get_alloc_bytes_unchecked_raw(&self, id: AllocId) -> InterpResult<'tcx, *const u8> { |
| let alloc = self.get_alloc_raw(id)?; |
| Ok(alloc.get_bytes_unchecked_raw()) |
| } |
| |
| /// Bounds-checked *but not align-checked* allocation access. |
| pub fn get_ptr_alloc<'a>( |
| &'a self, |
| ptr: Pointer<Option<M::Provenance>>, |
| size: Size, |
| ) -> InterpResult<'tcx, Option<AllocRef<'a, 'tcx, M::Provenance, M::AllocExtra, M::Bytes>>> |
| { |
| let size_i64 = i64::try_from(size.bytes()).unwrap(); // it would be an error to even ask for more than isize::MAX bytes |
| let ptr_and_alloc = self.check_and_deref_ptr( |
| ptr, |
| size_i64, |
| CheckInAllocMsg::MemoryAccessTest, |
| |alloc_id, offset, prov| { |
| let alloc = self.get_alloc_raw(alloc_id)?; |
| Ok((alloc.size(), alloc.align, (alloc_id, offset, prov, alloc))) |
| }, |
| )?; |
| // We want to call the hook on *all* accesses that involve an AllocId, including zero-sized |
| // accesses. That means we cannot rely on the closure above or the `Some` branch below. We |
| // do this after `check_and_deref_ptr` to ensure some basic sanity has already been checked. |
| if !self.memory.validation_in_progress.get() { |
| if let Ok((alloc_id, ..)) = self.ptr_try_get_alloc_id(ptr, size_i64) { |
| M::before_alloc_read(self, alloc_id)?; |
| } |
| } |
| |
| if let Some((alloc_id, offset, prov, alloc)) = ptr_and_alloc { |
| let range = alloc_range(offset, size); |
| if !self.memory.validation_in_progress.get() { |
| M::before_memory_read( |
| self.tcx, |
| &self.machine, |
| &alloc.extra, |
| (alloc_id, prov), |
| range, |
| )?; |
| } |
| Ok(Some(AllocRef { alloc, range, tcx: *self.tcx, alloc_id })) |
| } else { |
| Ok(None) |
| } |
| } |
| |
| /// Return the `extra` field of the given allocation. |
| pub fn get_alloc_extra<'a>(&'a self, id: AllocId) -> InterpResult<'tcx, &'a M::AllocExtra> { |
| Ok(&self.get_alloc_raw(id)?.extra) |
| } |
| |
| /// Return the `mutability` field of the given allocation. |
| pub fn get_alloc_mutability<'a>(&'a self, id: AllocId) -> InterpResult<'tcx, Mutability> { |
| Ok(self.get_alloc_raw(id)?.mutability) |
| } |
| |
| /// Gives raw mutable access to the `Allocation`, without bounds or alignment checks. |
| /// The caller is responsible for calling the access hooks! |
| /// |
| /// Also returns a ptr to `self.extra` so that the caller can use it in parallel with the |
| /// allocation. |
| fn get_alloc_raw_mut( |
| &mut self, |
| id: AllocId, |
| ) -> InterpResult<'tcx, (&mut Allocation<M::Provenance, M::AllocExtra, M::Bytes>, &mut M)> { |
| // We have "NLL problem case #3" here, which cannot be worked around without loss of |
| // efficiency even for the common case where the key is in the map. |
| // <https://rust-lang.github.io/rfcs/2094-nll.html#problem-case-3-conditional-control-flow-across-functions> |
| // (Cannot use `get_mut_or` since `get_global_alloc` needs `&self`.) |
| if self.memory.alloc_map.get_mut(id).is_none() { |
| // Slow path. |
| // Allocation not found locally, go look global. |
| let alloc = self.get_global_alloc(id, /*is_write*/ true)?; |
| let kind = M::GLOBAL_KIND.expect( |
| "I got a global allocation that I have to copy but the machine does \ |
| not expect that to happen", |
| ); |
| self.memory.alloc_map.insert(id, (MemoryKind::Machine(kind), alloc.into_owned())); |
| } |
| |
| let (_kind, alloc) = self.memory.alloc_map.get_mut(id).unwrap(); |
| if alloc.mutability.is_not() { |
| throw_ub!(WriteToReadOnly(id)) |
| } |
| Ok((alloc, &mut self.machine)) |
| } |
| |
| /// Gives raw, mutable access to the `Allocation` address, without bounds or alignment checks. |
| /// The caller is responsible for calling the access hooks! |
| pub fn get_alloc_bytes_unchecked_raw_mut( |
| &mut self, |
| id: AllocId, |
| ) -> InterpResult<'tcx, *mut u8> { |
| let alloc = self.get_alloc_raw_mut(id)?.0; |
| Ok(alloc.get_bytes_unchecked_raw_mut()) |
| } |
| |
| /// Bounds-checked *but not align-checked* allocation access. |
| pub fn get_ptr_alloc_mut<'a>( |
| &'a mut self, |
| ptr: Pointer<Option<M::Provenance>>, |
| size: Size, |
| ) -> InterpResult<'tcx, Option<AllocRefMut<'a, 'tcx, M::Provenance, M::AllocExtra, M::Bytes>>> |
| { |
| let parts = self.get_ptr_access(ptr, size)?; |
| if let Some((alloc_id, offset, prov)) = parts { |
| let tcx = self.tcx; |
| // FIXME: can we somehow avoid looking up the allocation twice here? |
| // We cannot call `get_raw_mut` inside `check_and_deref_ptr` as that would duplicate `&mut self`. |
| let (alloc, machine) = self.get_alloc_raw_mut(alloc_id)?; |
| let range = alloc_range(offset, size); |
| M::before_memory_write(tcx, machine, &mut alloc.extra, (alloc_id, prov), range)?; |
| Ok(Some(AllocRefMut { alloc, range, tcx: *tcx, alloc_id })) |
| } else { |
| Ok(None) |
| } |
| } |
| |
| /// Return the `extra` field of the given allocation. |
| pub fn get_alloc_extra_mut<'a>( |
| &'a mut self, |
| id: AllocId, |
| ) -> InterpResult<'tcx, (&'a mut M::AllocExtra, &'a mut M)> { |
| let (alloc, machine) = self.get_alloc_raw_mut(id)?; |
| Ok((&mut alloc.extra, machine)) |
| } |
| |
| /// Check whether an allocation is live. This is faster than calling |
| /// [`InterpCx::get_alloc_info`] if all you need to check is whether the kind is |
| /// [`AllocKind::Dead`] because it doesn't have to look up the type and layout of statics. |
| pub fn is_alloc_live(&self, id: AllocId) -> bool { |
| self.tcx.try_get_global_alloc(id).is_some() |
| || self.memory.alloc_map.contains_key_ref(&id) |
| || self.memory.extra_fn_ptr_map.contains_key(&id) |
| } |
| |
| /// Obtain the size and alignment of an allocation, even if that allocation has |
| /// been deallocated. |
| pub fn get_alloc_info(&self, id: AllocId) -> (Size, Align, AllocKind) { |
| // # Regular allocations |
| // Don't use `self.get_raw` here as that will |
| // a) cause cycles in case `id` refers to a static |
| // b) duplicate a global's allocation in miri |
| if let Some((_, alloc)) = self.memory.alloc_map.get(id) { |
| return (alloc.size(), alloc.align, AllocKind::LiveData); |
| } |
| |
| // # Function pointers |
| // (both global from `alloc_map` and local from `extra_fn_ptr_map`) |
| if self.get_fn_alloc(id).is_some() { |
| return (Size::ZERO, Align::ONE, AllocKind::Function); |
| } |
| |
| // # Statics |
| // Can't do this in the match argument, we may get cycle errors since the lock would |
| // be held throughout the match. |
| match self.tcx.try_get_global_alloc(id) { |
| Some(GlobalAlloc::Static(def_id)) => { |
| // Thread-local statics do not have a constant address. They *must* be accessed via |
| // `ThreadLocalRef`; we can never have a pointer to them as a regular constant value. |
| assert!(!self.tcx.is_thread_local_static(def_id)); |
| |
| let DefKind::Static { nested, .. } = self.tcx.def_kind(def_id) else { |
| bug!("GlobalAlloc::Static is not a static") |
| }; |
| |
| let (size, align) = if nested { |
| // Nested anonymous statics are untyped, so let's get their |
| // size and alignment from the allocaiton itself. This always |
| // succeeds, as the query is fed at DefId creation time, so no |
| // evaluation actually occurs. |
| let alloc = self.tcx.eval_static_initializer(def_id).unwrap(); |
| (alloc.0.size(), alloc.0.align) |
| } else { |
| // Use size and align of the type for everything else. We need |
| // to do that to |
| // * avoid cycle errors in case of self-referential statics, |
| // * be able to get information on extern statics. |
| let ty = self |
| .tcx |
| .type_of(def_id) |
| .no_bound_vars() |
| .expect("statics should not have generic parameters"); |
| let layout = self.tcx.layout_of(ParamEnv::empty().and(ty)).unwrap(); |
| assert!(layout.is_sized()); |
| (layout.size, layout.align.abi) |
| }; |
| (size, align, AllocKind::LiveData) |
| } |
| Some(GlobalAlloc::Memory(alloc)) => { |
| // Need to duplicate the logic here, because the global allocations have |
| // different associated types than the interpreter-local ones. |
| let alloc = alloc.inner(); |
| (alloc.size(), alloc.align, AllocKind::LiveData) |
| } |
| Some(GlobalAlloc::Function { .. }) => { |
| bug!("We already checked function pointers above") |
| } |
| Some(GlobalAlloc::VTable(..)) => { |
| // No data to be accessed here. But vtables are pointer-aligned. |
| return (Size::ZERO, self.tcx.data_layout.pointer_align.abi, AllocKind::VTable); |
| } |
| // The rest must be dead. |
| None => { |
| // Deallocated pointers are allowed, we should be able to find |
| // them in the map. |
| let (size, align) = *self |
| .memory |
| .dead_alloc_map |
| .get(&id) |
| .expect("deallocated pointers should all be recorded in `dead_alloc_map`"); |
| (size, align, AllocKind::Dead) |
| } |
| } |
| } |
| |
| /// Obtain the size and alignment of a *live* allocation. |
| fn get_live_alloc_size_and_align( |
| &self, |
| id: AllocId, |
| msg: CheckInAllocMsg, |
| ) -> InterpResult<'tcx, (Size, Align)> { |
| let (size, align, kind) = self.get_alloc_info(id); |
| if matches!(kind, AllocKind::Dead) { |
| throw_ub!(PointerUseAfterFree(id, msg)) |
| } |
| Ok((size, align)) |
| } |
| |
| fn get_fn_alloc(&self, id: AllocId) -> Option<FnVal<'tcx, M::ExtraFnVal>> { |
| if let Some(extra) = self.memory.extra_fn_ptr_map.get(&id) { |
| Some(FnVal::Other(*extra)) |
| } else { |
| match self.tcx.try_get_global_alloc(id) { |
| Some(GlobalAlloc::Function { instance, .. }) => Some(FnVal::Instance(instance)), |
| _ => None, |
| } |
| } |
| } |
| |
| pub fn get_ptr_fn( |
| &self, |
| ptr: Pointer<Option<M::Provenance>>, |
| ) -> InterpResult<'tcx, FnVal<'tcx, M::ExtraFnVal>> { |
| trace!("get_ptr_fn({:?})", ptr); |
| let (alloc_id, offset, _prov) = self.ptr_get_alloc_id(ptr, 0)?; |
| if offset.bytes() != 0 { |
| throw_ub!(InvalidFunctionPointer(Pointer::new(alloc_id, offset))) |
| } |
| self.get_fn_alloc(alloc_id) |
| .ok_or_else(|| err_ub!(InvalidFunctionPointer(Pointer::new(alloc_id, offset))).into()) |
| } |
| |
| /// Get the dynamic type of the given vtable pointer. |
| /// If `expected_trait` is `Some`, it must be a vtable for the given trait. |
| pub fn get_ptr_vtable_ty( |
| &self, |
| ptr: Pointer<Option<M::Provenance>>, |
| expected_trait: Option<&'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>>, |
| ) -> InterpResult<'tcx, Ty<'tcx>> { |
| trace!("get_ptr_vtable({:?})", ptr); |
| let (alloc_id, offset, _tag) = self.ptr_get_alloc_id(ptr, 0)?; |
| if offset.bytes() != 0 { |
| throw_ub!(InvalidVTablePointer(Pointer::new(alloc_id, offset))) |
| } |
| let Some(GlobalAlloc::VTable(ty, vtable_trait)) = self.tcx.try_get_global_alloc(alloc_id) |
| else { |
| throw_ub!(InvalidVTablePointer(Pointer::new(alloc_id, offset))) |
| }; |
| if let Some(expected_trait) = expected_trait { |
| self.check_vtable_for_type(vtable_trait, expected_trait)?; |
| } |
| Ok(ty) |
| } |
| |
| pub fn alloc_mark_immutable(&mut self, id: AllocId) -> InterpResult<'tcx> { |
| self.get_alloc_raw_mut(id)?.0.mutability = Mutability::Not; |
| Ok(()) |
| } |
| |
| /// Create a lazy debug printer that prints the given allocation and all allocations it points |
| /// to, recursively. |
| #[must_use] |
| pub fn dump_alloc<'a>(&'a self, id: AllocId) -> DumpAllocs<'a, 'tcx, M> { |
| self.dump_allocs(vec![id]) |
| } |
| |
| /// Create a lazy debug printer for a list of allocations and all allocations they point to, |
| /// recursively. |
| #[must_use] |
| pub fn dump_allocs<'a>(&'a self, mut allocs: Vec<AllocId>) -> DumpAllocs<'a, 'tcx, M> { |
| allocs.sort(); |
| allocs.dedup(); |
| DumpAllocs { ecx: self, allocs } |
| } |
| |
| /// Print the allocation's bytes, without any nested allocations. |
| pub fn print_alloc_bytes_for_diagnostics(&self, id: AllocId) -> String { |
| // Using the "raw" access to avoid the `before_alloc_read` hook, we specifically |
| // want to be able to read all memory for diagnostics, even if that is cyclic. |
| let alloc = self.get_alloc_raw(id).unwrap(); |
| let mut bytes = String::new(); |
| if alloc.size() != Size::ZERO { |
| bytes = "\n".into(); |
| // FIXME(translation) there might be pieces that are translatable. |
| rustc_middle::mir::pretty::write_allocation_bytes(*self.tcx, alloc, &mut bytes, " ") |
| .unwrap(); |
| } |
| bytes |
| } |
| |
| /// Find leaked allocations. Allocations reachable from `static_roots` or a `Global` allocation |
| /// are not considered leaked, as well as leaks whose kind's `may_leak()` returns true. |
| pub fn find_leaked_allocations( |
| &self, |
| static_roots: &[AllocId], |
| ) -> Vec<(AllocId, MemoryKind<M::MemoryKind>, Allocation<M::Provenance, M::AllocExtra, M::Bytes>)> |
| { |
| // Collect the set of allocations that are *reachable* from `Global` allocations. |
| let reachable = { |
| let mut reachable = FxHashSet::default(); |
| let global_kind = M::GLOBAL_KIND.map(MemoryKind::Machine); |
| let mut todo: Vec<_> = |
| self.memory.alloc_map.filter_map_collect(move |&id, &(kind, _)| { |
| if Some(kind) == global_kind { Some(id) } else { None } |
| }); |
| todo.extend(static_roots); |
| while let Some(id) = todo.pop() { |
| if reachable.insert(id) { |
| // This is a new allocation, add the allocation it points to `todo`. |
| if let Some((_, alloc)) = self.memory.alloc_map.get(id) { |
| todo.extend( |
| alloc.provenance().provenances().filter_map(|prov| prov.get_alloc_id()), |
| ); |
| } |
| } |
| } |
| reachable |
| }; |
| |
| // All allocations that are *not* `reachable` and *not* `may_leak` are considered leaking. |
| self.memory.alloc_map.filter_map_collect(|id, (kind, alloc)| { |
| if kind.may_leak() || reachable.contains(id) { |
| None |
| } else { |
| Some((*id, *kind, alloc.clone())) |
| } |
| }) |
| } |
| |
| /// Runs the close in "validation" mode, which means the machine's memory read hooks will be |
| /// suppressed. Needless to say, this must only be set with great care! Cannot be nested. |
| pub(super) fn run_for_validation<R>(&self, f: impl FnOnce() -> R) -> R { |
| // This deliberately uses `==` on `bool` to follow the pattern |
| // `assert!(val.replace(new) == old)`. |
| assert!( |
| self.memory.validation_in_progress.replace(true) == false, |
| "`validation_in_progress` was already set" |
| ); |
| let res = f(); |
| assert!( |
| self.memory.validation_in_progress.replace(false) == true, |
| "`validation_in_progress` was unset by someone else" |
| ); |
| res |
| } |
| } |
| |
| #[doc(hidden)] |
| /// There's no way to use this directly, it's just a helper struct for the `dump_alloc(s)` methods. |
| pub struct DumpAllocs<'a, 'tcx, M: Machine<'tcx>> { |
| ecx: &'a InterpCx<'tcx, M>, |
| allocs: Vec<AllocId>, |
| } |
| |
| impl<'a, 'tcx, M: Machine<'tcx>> std::fmt::Debug for DumpAllocs<'a, 'tcx, M> { |
| fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { |
| // Cannot be a closure because it is generic in `Prov`, `Extra`. |
| fn write_allocation_track_relocs<'tcx, Prov: Provenance, Extra, Bytes: AllocBytes>( |
| fmt: &mut std::fmt::Formatter<'_>, |
| tcx: TyCtxt<'tcx>, |
| allocs_to_print: &mut VecDeque<AllocId>, |
| alloc: &Allocation<Prov, Extra, Bytes>, |
| ) -> std::fmt::Result { |
| for alloc_id in alloc.provenance().provenances().filter_map(|prov| prov.get_alloc_id()) |
| { |
| allocs_to_print.push_back(alloc_id); |
| } |
| write!(fmt, "{}", display_allocation(tcx, alloc)) |
| } |
| |
| let mut allocs_to_print: VecDeque<_> = self.allocs.iter().copied().collect(); |
| // `allocs_printed` contains all allocations that we have already printed. |
| let mut allocs_printed = FxHashSet::default(); |
| |
| while let Some(id) = allocs_to_print.pop_front() { |
| if !allocs_printed.insert(id) { |
| // Already printed, so skip this. |
| continue; |
| } |
| |
| write!(fmt, "{id:?}")?; |
| match self.ecx.memory.alloc_map.get(id) { |
| Some((kind, alloc)) => { |
| // normal alloc |
| write!(fmt, " ({kind}, ")?; |
| write_allocation_track_relocs( |
| &mut *fmt, |
| *self.ecx.tcx, |
| &mut allocs_to_print, |
| alloc, |
| )?; |
| } |
| None => { |
| // global alloc |
| match self.ecx.tcx.try_get_global_alloc(id) { |
| Some(GlobalAlloc::Memory(alloc)) => { |
| write!(fmt, " (unchanged global, ")?; |
| write_allocation_track_relocs( |
| &mut *fmt, |
| *self.ecx.tcx, |
| &mut allocs_to_print, |
| alloc.inner(), |
| )?; |
| } |
| Some(GlobalAlloc::Function { instance, .. }) => { |
| write!(fmt, " (fn: {instance})")?; |
| } |
| Some(GlobalAlloc::VTable(ty, Some(trait_ref))) => { |
| write!(fmt, " (vtable: impl {trait_ref} for {ty})")?; |
| } |
| Some(GlobalAlloc::VTable(ty, None)) => { |
| write!(fmt, " (vtable: impl <auto trait> for {ty})")?; |
| } |
| Some(GlobalAlloc::Static(did)) => { |
| write!(fmt, " (static: {})", self.ecx.tcx.def_path_str(did))?; |
| } |
| None => { |
| write!(fmt, " (deallocated)")?; |
| } |
| } |
| } |
| } |
| writeln!(fmt)?; |
| } |
| Ok(()) |
| } |
| } |
| |
| /// Reading and writing. |
| impl<'tcx, 'a, Prov: Provenance, Extra, Bytes: AllocBytes> |
| AllocRefMut<'a, 'tcx, Prov, Extra, Bytes> |
| { |
| /// `range` is relative to this allocation reference, not the base of the allocation. |
| pub fn write_scalar(&mut self, range: AllocRange, val: Scalar<Prov>) -> InterpResult<'tcx> { |
| let range = self.range.subrange(range); |
| debug!("write_scalar at {:?}{range:?}: {val:?}", self.alloc_id); |
| Ok(self |
| .alloc |
| .write_scalar(&self.tcx, range, val) |
| .map_err(|e| e.to_interp_error(self.alloc_id))?) |
| } |
| |
| /// `offset` is relative to this allocation reference, not the base of the allocation. |
| pub fn write_ptr_sized(&mut self, offset: Size, val: Scalar<Prov>) -> InterpResult<'tcx> { |
| self.write_scalar(alloc_range(offset, self.tcx.data_layout().pointer_size), val) |
| } |
| |
| /// Mark the entire referenced range as uninitialized |
| pub fn write_uninit(&mut self) -> InterpResult<'tcx> { |
| Ok(self |
| .alloc |
| .write_uninit(&self.tcx, self.range) |
| .map_err(|e| e.to_interp_error(self.alloc_id))?) |
| } |
| } |
| |
| impl<'tcx, 'a, Prov: Provenance, Extra, Bytes: AllocBytes> AllocRef<'a, 'tcx, Prov, Extra, Bytes> { |
| /// `range` is relative to this allocation reference, not the base of the allocation. |
| pub fn read_scalar( |
| &self, |
| range: AllocRange, |
| read_provenance: bool, |
| ) -> InterpResult<'tcx, Scalar<Prov>> { |
| let range = self.range.subrange(range); |
| let res = self |
| .alloc |
| .read_scalar(&self.tcx, range, read_provenance) |
| .map_err(|e| e.to_interp_error(self.alloc_id))?; |
| debug!("read_scalar at {:?}{range:?}: {res:?}", self.alloc_id); |
| Ok(res) |
| } |
| |
| /// `range` is relative to this allocation reference, not the base of the allocation. |
| pub fn read_integer(&self, range: AllocRange) -> InterpResult<'tcx, Scalar<Prov>> { |
| self.read_scalar(range, /*read_provenance*/ false) |
| } |
| |
| /// `offset` is relative to this allocation reference, not the base of the allocation. |
| pub fn read_pointer(&self, offset: Size) -> InterpResult<'tcx, Scalar<Prov>> { |
| self.read_scalar( |
| alloc_range(offset, self.tcx.data_layout().pointer_size), |
| /*read_provenance*/ true, |
| ) |
| } |
| |
| /// `range` is relative to this allocation reference, not the base of the allocation. |
| pub fn get_bytes_strip_provenance<'b>(&'b self) -> InterpResult<'tcx, &'a [u8]> { |
| Ok(self |
| .alloc |
| .get_bytes_strip_provenance(&self.tcx, self.range) |
| .map_err(|e| e.to_interp_error(self.alloc_id))?) |
| } |
| |
| /// Returns whether the allocation has provenance anywhere in the range of the `AllocRef`. |
| pub fn has_provenance(&self) -> bool { |
| !self.alloc.provenance().range_empty(self.range, &self.tcx) |
| } |
| } |
| |
| impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { |
| /// Reads the given number of bytes from memory, and strips their provenance if possible. |
| /// Returns them as a slice. |
| /// |
| /// Performs appropriate bounds checks. |
| pub fn read_bytes_ptr_strip_provenance( |
| &self, |
| ptr: Pointer<Option<M::Provenance>>, |
| size: Size, |
| ) -> InterpResult<'tcx, &[u8]> { |
| let Some(alloc_ref) = self.get_ptr_alloc(ptr, size)? else { |
| // zero-sized access |
| return Ok(&[]); |
| }; |
| // Side-step AllocRef and directly access the underlying bytes more efficiently. |
| // (We are staying inside the bounds here so all is good.) |
| Ok(alloc_ref |
| .alloc |
| .get_bytes_strip_provenance(&alloc_ref.tcx, alloc_ref.range) |
| .map_err(|e| e.to_interp_error(alloc_ref.alloc_id))?) |
| } |
| |
| /// Writes the given stream of bytes into memory. |
| /// |
| /// Performs appropriate bounds checks. |
| pub fn write_bytes_ptr( |
| &mut self, |
| ptr: Pointer<Option<M::Provenance>>, |
| src: impl IntoIterator<Item = u8>, |
| ) -> InterpResult<'tcx> { |
| let mut src = src.into_iter(); |
| let (lower, upper) = src.size_hint(); |
| let len = upper.expect("can only write bounded iterators"); |
| assert_eq!(lower, len, "can only write iterators with a precise length"); |
| |
| let size = Size::from_bytes(len); |
| let Some(alloc_ref) = self.get_ptr_alloc_mut(ptr, size)? else { |
| // zero-sized access |
| assert_matches!(src.next(), None, "iterator said it was empty but returned an element"); |
| return Ok(()); |
| }; |
| |
| // Side-step AllocRef and directly access the underlying bytes more efficiently. |
| // (We are staying inside the bounds here and all bytes do get overwritten so all is good.) |
| let alloc_id = alloc_ref.alloc_id; |
| let bytes = alloc_ref |
| .alloc |
| .get_bytes_unchecked_for_overwrite(&alloc_ref.tcx, alloc_ref.range) |
| .map_err(move |e| e.to_interp_error(alloc_id))?; |
| // `zip` would stop when the first iterator ends; we want to definitely |
| // cover all of `bytes`. |
| for dest in bytes { |
| *dest = src.next().expect("iterator was shorter than it said it would be"); |
| } |
| assert_matches!(src.next(), None, "iterator was longer than it said it would be"); |
| Ok(()) |
| } |
| |
| pub fn mem_copy( |
| &mut self, |
| src: Pointer<Option<M::Provenance>>, |
| dest: Pointer<Option<M::Provenance>>, |
| size: Size, |
| nonoverlapping: bool, |
| ) -> InterpResult<'tcx> { |
| self.mem_copy_repeatedly(src, dest, size, 1, nonoverlapping) |
| } |
| |
| /// Performs `num_copies` many copies of `size` many bytes from `src` to `dest + i*size` (where |
| /// `i` is the index of the copy). |
| /// |
| /// Either `nonoverlapping` must be true or `num_copies` must be 1; doing repeated copies that |
| /// may overlap is not supported. |
| pub fn mem_copy_repeatedly( |
| &mut self, |
| src: Pointer<Option<M::Provenance>>, |
| dest: Pointer<Option<M::Provenance>>, |
| size: Size, |
| num_copies: u64, |
| nonoverlapping: bool, |
| ) -> InterpResult<'tcx> { |
| let tcx = self.tcx; |
| // We need to do our own bounds-checks. |
| let src_parts = self.get_ptr_access(src, size)?; |
| let dest_parts = self.get_ptr_access(dest, size * num_copies)?; // `Size` multiplication |
| |
| // FIXME: we look up both allocations twice here, once before for the `check_ptr_access` |
| // and once below to get the underlying `&[mut] Allocation`. |
| |
| // Source alloc preparations and access hooks. |
| let Some((src_alloc_id, src_offset, src_prov)) = src_parts else { |
| // Zero-sized *source*, that means dest is also zero-sized and we have nothing to do. |
| return Ok(()); |
| }; |
| let src_alloc = self.get_alloc_raw(src_alloc_id)?; |
| let src_range = alloc_range(src_offset, size); |
| assert!(!self.memory.validation_in_progress.get(), "we can't be copying during validation"); |
| M::before_memory_read( |
| tcx, |
| &self.machine, |
| &src_alloc.extra, |
| (src_alloc_id, src_prov), |
| src_range, |
| )?; |
| // We need the `dest` ptr for the next operation, so we get it now. |
| // We already did the source checks and called the hooks so we are good to return early. |
| let Some((dest_alloc_id, dest_offset, dest_prov)) = dest_parts else { |
| // Zero-sized *destination*. |
| return Ok(()); |
| }; |
| |
| // Prepare getting source provenance. |
| let src_bytes = src_alloc.get_bytes_unchecked(src_range).as_ptr(); // raw ptr, so we can also get a ptr to the destination allocation |
| // first copy the provenance to a temporary buffer, because |
| // `get_bytes_mut` will clear the provenance, which is correct, |
| // since we don't want to keep any provenance at the target. |
| // This will also error if copying partial provenance is not supported. |
| let provenance = src_alloc |
| .provenance() |
| .prepare_copy(src_range, dest_offset, num_copies, self) |
| .map_err(|e| e.to_interp_error(dest_alloc_id))?; |
| // Prepare a copy of the initialization mask. |
| let init = src_alloc.init_mask().prepare_copy(src_range); |
| |
| // Destination alloc preparations and access hooks. |
| let (dest_alloc, extra) = self.get_alloc_raw_mut(dest_alloc_id)?; |
| let dest_range = alloc_range(dest_offset, size * num_copies); |
| M::before_memory_write( |
| tcx, |
| extra, |
| &mut dest_alloc.extra, |
| (dest_alloc_id, dest_prov), |
| dest_range, |
| )?; |
| // Yes we do overwrite all bytes in `dest_bytes`. |
| let dest_bytes = dest_alloc |
| .get_bytes_unchecked_for_overwrite_ptr(&tcx, dest_range) |
| .map_err(|e| e.to_interp_error(dest_alloc_id))? |
| .as_mut_ptr(); |
| |
| if init.no_bytes_init() { |
| // Fast path: If all bytes are `uninit` then there is nothing to copy. The target range |
| // is marked as uninitialized but we otherwise omit changing the byte representation which may |
| // be arbitrary for uninitialized bytes. |
| // This also avoids writing to the target bytes so that the backing allocation is never |
| // touched if the bytes stay uninitialized for the whole interpreter execution. On contemporary |
| // operating system this can avoid physically allocating the page. |
| dest_alloc |
| .write_uninit(&tcx, dest_range) |
| .map_err(|e| e.to_interp_error(dest_alloc_id))?; |
| // We can forget about the provenance, this is all not initialized anyway. |
| return Ok(()); |
| } |
| |
| // SAFE: The above indexing would have panicked if there weren't at least `size` bytes |
| // behind `src` and `dest`. Also, we use the overlapping-safe `ptr::copy` if `src` and |
| // `dest` could possibly overlap. |
| // The pointers above remain valid even if the `HashMap` table is moved around because they |
| // point into the `Vec` storing the bytes. |
| unsafe { |
| if src_alloc_id == dest_alloc_id { |
| if nonoverlapping { |
| // `Size` additions |
| if (src_offset <= dest_offset && src_offset + size > dest_offset) |
| || (dest_offset <= src_offset && dest_offset + size > src_offset) |
| { |
| throw_ub_custom!(fluent::const_eval_copy_nonoverlapping_overlapping); |
| } |
| } |
| } |
| if num_copies > 1 { |
| assert!(nonoverlapping, "multi-copy only supported in non-overlapping mode"); |
| } |
| |
| let size_in_bytes = size.bytes_usize(); |
| // For particularly large arrays (where this is perf-sensitive) it's common that |
| // we're writing a single byte repeatedly. So, optimize that case to a memset. |
| if size_in_bytes == 1 { |
| debug_assert!(num_copies >= 1); // we already handled the zero-sized cases above. |
| // SAFETY: `src_bytes` would be read from anyway by `copy` below (num_copies >= 1). |
| let value = *src_bytes; |
| dest_bytes.write_bytes(value, (size * num_copies).bytes_usize()); |
| } else if src_alloc_id == dest_alloc_id { |
| let mut dest_ptr = dest_bytes; |
| for _ in 0..num_copies { |
| // Here we rely on `src` and `dest` being non-overlapping if there is more than |
| // one copy. |
| ptr::copy(src_bytes, dest_ptr, size_in_bytes); |
| dest_ptr = dest_ptr.add(size_in_bytes); |
| } |
| } else { |
| let mut dest_ptr = dest_bytes; |
| for _ in 0..num_copies { |
| ptr::copy_nonoverlapping(src_bytes, dest_ptr, size_in_bytes); |
| dest_ptr = dest_ptr.add(size_in_bytes); |
| } |
| } |
| } |
| |
| // now fill in all the "init" data |
| dest_alloc.init_mask_apply_copy( |
| init, |
| alloc_range(dest_offset, size), // just a single copy (i.e., not full `dest_range`) |
| num_copies, |
| ); |
| // copy the provenance to the destination |
| dest_alloc.provenance_apply_copy(provenance); |
| |
| Ok(()) |
| } |
| } |
| |
| /// Machine pointer introspection. |
| impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { |
| /// Test if this value might be null. |
| /// If the machine does not support ptr-to-int casts, this is conservative. |
| pub fn scalar_may_be_null(&self, scalar: Scalar<M::Provenance>) -> InterpResult<'tcx, bool> { |
| Ok(match scalar.try_to_scalar_int() { |
| Ok(int) => int.is_null(), |
| Err(_) => { |
| // Can only happen during CTFE. |
| let ptr = scalar.to_pointer(self)?; |
| match self.ptr_try_get_alloc_id(ptr, 0) { |
| Ok((alloc_id, offset, _)) => { |
| let (size, _align, _kind) = self.get_alloc_info(alloc_id); |
| // If the pointer is out-of-bounds, it may be null. |
| // Note that one-past-the-end (offset == size) is still inbounds, and never null. |
| offset > size |
| } |
| Err(_offset) => bug!("a non-int scalar is always a pointer"), |
| } |
| } |
| }) |
| } |
| |
| /// Turning a "maybe pointer" into a proper pointer (and some information |
| /// about where it points), or an absolute address. |
| /// |
| /// `size` says how many bytes of memory are expected at that pointer. This is largely only used |
| /// for error messages; however, the *sign* of `size` can be used to disambiguate situations |
| /// where a wildcard pointer sits right in between two allocations. |
| /// It is almost always okay to just set the size to 0; this will be treated like a positive size |
| /// for handling wildcard pointers. |
| /// |
| /// The result must be used immediately; it is not allowed to convert |
| /// the returned data back into a `Pointer` and store that in machine state. |
| /// (In fact that's not even possible since `M::ProvenanceExtra` is generic and |
| /// we don't have an operation to turn it back into `M::Provenance`.) |
| pub fn ptr_try_get_alloc_id( |
| &self, |
| ptr: Pointer<Option<M::Provenance>>, |
| size: i64, |
| ) -> Result<(AllocId, Size, M::ProvenanceExtra), u64> { |
| match ptr.into_pointer_or_addr() { |
| Ok(ptr) => match M::ptr_get_alloc(self, ptr, size) { |
| Some((alloc_id, offset, extra)) => Ok((alloc_id, offset, extra)), |
| None => { |
| assert!(M::Provenance::OFFSET_IS_ADDR); |
| let (_, addr) = ptr.into_parts(); |
| Err(addr.bytes()) |
| } |
| }, |
| Err(addr) => Err(addr.bytes()), |
| } |
| } |
| |
| /// Turning a "maybe pointer" into a proper pointer (and some information about where it points). |
| /// |
| /// `size` says how many bytes of memory are expected at that pointer. This is largely only used |
| /// for error messages; however, the *sign* of `size` can be used to disambiguate situations |
| /// where a wildcard pointer sits right in between two allocations. |
| /// It is almost always okay to just set the size to 0; this will be treated like a positive size |
| /// for handling wildcard pointers. |
| /// |
| /// The result must be used immediately; it is not allowed to convert |
| /// the returned data back into a `Pointer` and store that in machine state. |
| /// (In fact that's not even possible since `M::ProvenanceExtra` is generic and |
| /// we don't have an operation to turn it back into `M::Provenance`.) |
| #[inline(always)] |
| pub fn ptr_get_alloc_id( |
| &self, |
| ptr: Pointer<Option<M::Provenance>>, |
| size: i64, |
| ) -> InterpResult<'tcx, (AllocId, Size, M::ProvenanceExtra)> { |
| self.ptr_try_get_alloc_id(ptr, size).map_err(|offset| { |
| err_ub!(DanglingIntPointer { |
| addr: offset, |
| inbounds_size: size, |
| msg: CheckInAllocMsg::InboundsTest |
| }) |
| .into() |
| }) |
| } |
| } |
