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Auto merge of #104054 - RalfJung:byte-provenance, r=oli-obk
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interpret: support for per-byte provenance

Also factors the provenance map into its own module.

The third commit does the same for the init mask. I can move it in a separate PR if you prefer.

Fixes rust-lang/miri#2181

r? `@oli-obk`
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bors committed Nov 15, 2022
2 parents 6d651a2 + 68af46c commit a00f8ba
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Showing 30 changed files with 1,253 additions and 959 deletions.
4 changes: 2 additions & 2 deletions compiler/rustc_codegen_cranelift/src/constant.rs
Original file line number Diff line number Diff line change
Expand Up @@ -398,7 +398,7 @@ fn define_all_allocs(tcx: TyCtxt<'_>, module: &mut dyn Module, cx: &mut Constant
let bytes = alloc.inspect_with_uninit_and_ptr_outside_interpreter(0..alloc.len()).to_vec();
data_ctx.define(bytes.into_boxed_slice());

for &(offset, alloc_id) in alloc.provenance().iter() {
for &(offset, alloc_id) in alloc.provenance().ptrs().iter() {
let addend = {
let endianness = tcx.data_layout.endian;
let offset = offset.bytes() as usize;
Expand Down Expand Up @@ -431,7 +431,7 @@ fn define_all_allocs(tcx: TyCtxt<'_>, module: &mut dyn Module, cx: &mut Constant
{
tcx.sess.fatal(&format!(
"Allocation {:?} contains reference to TLS value {:?}",
alloc, def_id
alloc_id, def_id
));
}

Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_codegen_gcc/src/consts.rs
Original file line number Diff line number Diff line change
Expand Up @@ -297,12 +297,12 @@ impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {

pub fn const_alloc_to_gcc<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, alloc: ConstAllocation<'tcx>) -> RValue<'gcc> {
let alloc = alloc.inner();
let mut llvals = Vec::with_capacity(alloc.provenance().len() + 1);
let mut llvals = Vec::with_capacity(alloc.provenance().ptrs().len() + 1);
let dl = cx.data_layout();
let pointer_size = dl.pointer_size.bytes() as usize;

let mut next_offset = 0;
for &(offset, alloc_id) in alloc.provenance().iter() {
for &(offset, alloc_id) in alloc.provenance().ptrs().iter() {
let offset = offset.bytes();
assert_eq!(offset as usize as u64, offset);
let offset = offset as usize;
Expand Down
12 changes: 5 additions & 7 deletions compiler/rustc_codegen_llvm/src/consts.rs
Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ use std::ops::Range;

pub fn const_alloc_to_llvm<'ll>(cx: &CodegenCx<'ll, '_>, alloc: ConstAllocation<'_>) -> &'ll Value {
let alloc = alloc.inner();
let mut llvals = Vec::with_capacity(alloc.provenance().len() + 1);
let mut llvals = Vec::with_capacity(alloc.provenance().ptrs().len() + 1);
let dl = cx.data_layout();
let pointer_size = dl.pointer_size.bytes() as usize;

Expand All @@ -40,9 +40,7 @@ pub fn const_alloc_to_llvm<'ll>(cx: &CodegenCx<'ll, '_>, alloc: ConstAllocation<
alloc: &'a Allocation,
range: Range<usize>,
) {
let chunks = alloc
.init_mask()
.range_as_init_chunks(Size::from_bytes(range.start), Size::from_bytes(range.end));
let chunks = alloc.init_mask().range_as_init_chunks(range.clone().into());

let chunk_to_llval = move |chunk| match chunk {
InitChunk::Init(range) => {
Expand Down Expand Up @@ -80,7 +78,7 @@ pub fn const_alloc_to_llvm<'ll>(cx: &CodegenCx<'ll, '_>, alloc: ConstAllocation<
}

let mut next_offset = 0;
for &(offset, alloc_id) in alloc.provenance().iter() {
for &(offset, alloc_id) in alloc.provenance().ptrs().iter() {
let offset = offset.bytes();
assert_eq!(offset as usize as u64, offset);
let offset = offset as usize;
Expand Down Expand Up @@ -489,7 +487,7 @@ impl<'ll> StaticMethods for CodegenCx<'ll, '_> {
// happens to be zero. Instead, we should only check the value of defined bytes
// and set all undefined bytes to zero if this allocation is headed for the
// BSS.
let all_bytes_are_zero = alloc.provenance().is_empty()
let all_bytes_are_zero = alloc.provenance().ptrs().is_empty()
&& alloc
.inspect_with_uninit_and_ptr_outside_interpreter(0..alloc.len())
.iter()
Expand All @@ -513,7 +511,7 @@ impl<'ll> StaticMethods for CodegenCx<'ll, '_> {
section.as_str().as_ptr().cast(),
section.as_str().len() as c_uint,
);
assert!(alloc.provenance().is_empty());
assert!(alloc.provenance().ptrs().is_empty());

// The `inspect` method is okay here because we checked for provenance, and
// because we are doing this access to inspect the final interpreter state (not
Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_const_eval/src/interpret/intern.rs
Original file line number Diff line number Diff line change
Expand Up @@ -134,7 +134,7 @@ fn intern_shallow<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx, const_eval:
alloc.mutability = Mutability::Not;
};
// link the alloc id to the actual allocation
leftover_allocations.extend(alloc.provenance().iter().map(|&(_, alloc_id)| alloc_id));
leftover_allocations.extend(alloc.provenance().ptrs().iter().map(|&(_, alloc_id)| alloc_id));
let alloc = tcx.intern_const_alloc(alloc);
tcx.set_alloc_id_memory(alloc_id, alloc);
None
Expand Down Expand Up @@ -439,7 +439,7 @@ pub fn intern_const_alloc_recursive<
}
let alloc = tcx.intern_const_alloc(alloc);
tcx.set_alloc_id_memory(alloc_id, alloc);
for &(_, alloc_id) in alloc.inner().provenance().iter() {
for &(_, alloc_id) in alloc.inner().provenance().ptrs().iter() {
if leftover_allocations.insert(alloc_id) {
todo.push(alloc_id);
}
Expand Down
41 changes: 18 additions & 23 deletions compiler/rustc_const_eval/src/interpret/memory.rs
Original file line number Diff line number Diff line change
Expand Up @@ -112,15 +112,15 @@ pub struct Memory<'mir, 'tcx, M: Machine<'mir, 'tcx>> {
/// 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, Extra> {
pub struct AllocRef<'a, 'tcx, Prov: Provenance, Extra> {
alloc: &'a Allocation<Prov, Extra>,
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, Extra> {
pub struct AllocRefMut<'a, 'tcx, Prov: Provenance, Extra> {
alloc: &'a mut Allocation<Prov, Extra>,
range: AllocRange,
tcx: TyCtxt<'tcx>,
Expand Down Expand Up @@ -302,8 +302,6 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
.into());
};

debug!(?alloc);

if alloc.mutability == Mutability::Not {
throw_ub_format!("deallocating immutable allocation {alloc_id:?}");
}
Expand Down Expand Up @@ -797,7 +795,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// 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().values().filter_map(|prov| prov.get_alloc_id()),
alloc.provenance().provenances().filter_map(|prov| prov.get_alloc_id()),
);
}
}
Expand Down Expand Up @@ -833,7 +831,8 @@ impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> std::fmt::Debug for DumpAllocs<'a,
allocs_to_print: &mut VecDeque<AllocId>,
alloc: &Allocation<Prov, Extra>,
) -> std::fmt::Result {
for alloc_id in alloc.provenance().values().filter_map(|prov| prov.get_alloc_id()) {
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))
Expand Down Expand Up @@ -962,7 +961,7 @@ impl<'tcx, 'a, Prov: Provenance, Extra> AllocRef<'a, 'tcx, Prov, Extra> {

/// Returns whether the allocation has provenance anywhere in the range of the `AllocRef`.
pub(crate) fn has_provenance(&self) -> bool {
self.alloc.range_has_provenance(&self.tcx, self.range)
!self.alloc.provenance().range_empty(self.range, &self.tcx)
}
}

Expand Down Expand Up @@ -1060,7 +1059,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {

// Source alloc preparations and access hooks.
let Some((src_alloc_id, src_offset, src_prov)) = src_parts else {
// Zero-sized *source*, that means dst is also zero-sized and we have nothing to do.
// 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)?;
Expand All @@ -1079,22 +1078,18 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
return Ok(());
};

// Checks provenance edges on the src, which needs to happen before
// `prepare_provenance_copy`.
if src_alloc.range_has_provenance(&tcx, alloc_range(src_range.start, Size::ZERO)) {
throw_unsup!(PartialPointerCopy(Pointer::new(src_alloc_id, src_range.start)));
}
if src_alloc.range_has_provenance(&tcx, alloc_range(src_range.end(), Size::ZERO)) {
throw_unsup!(PartialPointerCopy(Pointer::new(src_alloc_id, src_range.end())));
}
// 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.
let provenance =
src_alloc.prepare_provenance_copy(self, src_range, dest_offset, num_copies);
// 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 compressed = src_alloc.compress_uninit_range(src_range);
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)?;
Expand All @@ -1111,7 +1106,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
.map_err(|e| e.to_interp_error(dest_alloc_id))?
.as_mut_ptr();

if compressed.no_bytes_init() {
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.
Expand Down Expand Up @@ -1160,13 +1155,13 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
}

// now fill in all the "init" data
dest_alloc.mark_compressed_init_range(
&compressed,
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.mark_provenance_range(provenance);
dest_alloc.provenance_apply_copy(provenance);

Ok(())
}
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_hir_analysis/src/check/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -159,7 +159,7 @@ fn maybe_check_static_with_link_section(tcx: TyCtxt<'_>, id: LocalDefId) {
// the consumer's responsibility to ensure all bytes that have been read
// have defined values.
if let Ok(alloc) = tcx.eval_static_initializer(id.to_def_id())
&& alloc.inner().provenance().len() != 0
&& alloc.inner().provenance().ptrs().len() != 0
{
let msg = "statics with a custom `#[link_section]` must be a \
simple list of bytes on the wasm target with no \
Expand Down
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