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switch intptrcast to helper trait pattern like everything else

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This commit is contained in:
Ralf Jung 2023-10-14 12:01:47 +02:00
parent f3863294a8
commit 55ce55d965
3 changed files with 94 additions and 95 deletions
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178
src/tools/miri/src/intptrcast.rs
View File

@ -62,10 +62,21 @@ impl GlobalStateInner {
}
}
impl<'mir, 'tcx> GlobalStateInner {
/// Shifts `addr` to make it aligned with `align` by rounding `addr` to the smallest multiple
/// of `align` that is larger or equal to `addr`
fn align_addr(addr: u64, align: u64) -> u64 {
match addr % align {
0 => addr,
rem => addr.checked_add(align).unwrap() - rem,
}
}
impl<'mir, 'tcx: 'mir> EvalContextExtPriv<'mir, 'tcx> for crate::MiriInterpCx<'mir, 'tcx> {}
trait EvalContextExtPriv<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
// Returns the exposed `AllocId` that corresponds to the specified addr,
// or `None` if the addr is out of bounds
fn alloc_id_from_addr(ecx: &MiriInterpCx<'mir, 'tcx>, addr: u64) -> Option<AllocId> {
fn alloc_id_from_addr(&self, addr: u64) -> Option<AllocId> {
let ecx = self.eval_context_ref();
let global_state = ecx.machine.intptrcast.borrow();
assert!(global_state.provenance_mode != ProvenanceMode::Strict);
@ -105,11 +116,66 @@ impl<'mir, 'tcx> GlobalStateInner {
None
}
pub fn expose_ptr(
ecx: &mut MiriInterpCx<'mir, 'tcx>,
alloc_id: AllocId,
tag: BorTag,
) -> InterpResult<'tcx> {
fn addr_from_alloc_id(&self, alloc_id: AllocId) -> InterpResult<'tcx, u64> {
let ecx = self.eval_context_ref();
let mut global_state = ecx.machine.intptrcast.borrow_mut();
let global_state = &mut *global_state;
Ok(match global_state.base_addr.entry(alloc_id) {
Entry::Occupied(entry) => *entry.get(),
Entry::Vacant(entry) => {
// There is nothing wrong with a raw pointer being cast to an integer only after
// it became dangling. Hence we allow dead allocations.
let (size, align, _kind) = ecx.get_alloc_info(alloc_id);
// This allocation does not have a base address yet, pick one.
// Leave some space to the previous allocation, to give it some chance to be less aligned.
let slack = {
let mut rng = ecx.machine.rng.borrow_mut();
// This means that `(global_state.next_base_addr + slack) % 16` is uniformly distributed.
rng.gen_range(0..16)
};
// From next_base_addr + slack, round up to adjust for alignment.
let base_addr = global_state
.next_base_addr
.checked_add(slack)
.ok_or_else(|| err_exhaust!(AddressSpaceFull))?;
let base_addr = align_addr(base_addr, align.bytes());
entry.insert(base_addr);
trace!(
"Assigning base address {:#x} to allocation {:?} (size: {}, align: {}, slack: {})",
base_addr,
alloc_id,
size.bytes(),
align.bytes(),
slack,
);
// Remember next base address. If this allocation is zero-sized, leave a gap
// of at least 1 to avoid two allocations having the same base address.
// (The logic in `alloc_id_from_addr` assumes unique addresses, and different
// function/vtable pointers need to be distinguishable!)
global_state.next_base_addr = base_addr
.checked_add(max(size.bytes(), 1))
.ok_or_else(|| err_exhaust!(AddressSpaceFull))?;
// Even if `Size` didn't overflow, we might still have filled up the address space.
if global_state.next_base_addr > ecx.target_usize_max() {
throw_exhaust!(AddressSpaceFull);
}
// Given that `next_base_addr` increases in each allocation, pushing the
// corresponding tuple keeps `int_to_ptr_map` sorted
global_state.int_to_ptr_map.push((base_addr, alloc_id));
base_addr
}
})
}
}
impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriInterpCx<'mir, 'tcx> {}
pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
fn expose_ptr(&mut self, alloc_id: AllocId, tag: BorTag) -> InterpResult<'tcx> {
let ecx = self.eval_context_mut();
let global_state = ecx.machine.intptrcast.get_mut();
// In strict mode, we don't need this, so we can save some cycles by not tracking it.
if global_state.provenance_mode != ProvenanceMode::Strict {
@ -122,14 +188,13 @@ impl<'mir, 'tcx> GlobalStateInner {
Ok(())
}
pub fn ptr_from_addr_cast(
ecx: &MiriInterpCx<'mir, 'tcx>,
addr: u64,
) -> InterpResult<'tcx, Pointer<Option<Provenance>>> {
fn ptr_from_addr_cast(&self, addr: u64) -> InterpResult<'tcx, Pointer<Option<Provenance>>> {
trace!("Casting {:#x} to a pointer", addr);
// Potentially emit a warning.
let ecx = self.eval_context_ref();
let global_state = ecx.machine.intptrcast.borrow();
// Potentially emit a warning.
match global_state.provenance_mode {
ProvenanceMode::Default => {
// The first time this happens at a particular location, print a warning.
@ -160,71 +225,16 @@ impl<'mir, 'tcx> GlobalStateInner {
Ok(Pointer::new(Some(Provenance::Wildcard), Size::from_bytes(addr)))
}
fn alloc_base_addr(
ecx: &MiriInterpCx<'mir, 'tcx>,
alloc_id: AllocId,
) -> InterpResult<'tcx, u64> {
let mut global_state = ecx.machine.intptrcast.borrow_mut();
let global_state = &mut *global_state;
Ok(match global_state.base_addr.entry(alloc_id) {
Entry::Occupied(entry) => *entry.get(),
Entry::Vacant(entry) => {
// There is nothing wrong with a raw pointer being cast to an integer only after
// it became dangling. Hence we allow dead allocations.
let (size, align, _kind) = ecx.get_alloc_info(alloc_id);
// This allocation does not have a base address yet, pick one.
// Leave some space to the previous allocation, to give it some chance to be less aligned.
let slack = {
let mut rng = ecx.machine.rng.borrow_mut();
// This means that `(global_state.next_base_addr + slack) % 16` is uniformly distributed.
rng.gen_range(0..16)
};
// From next_base_addr + slack, round up to adjust for alignment.
let base_addr = global_state
.next_base_addr
.checked_add(slack)
.ok_or_else(|| err_exhaust!(AddressSpaceFull))?;
let base_addr = Self::align_addr(base_addr, align.bytes());
entry.insert(base_addr);
trace!(
"Assigning base address {:#x} to allocation {:?} (size: {}, align: {}, slack: {})",
base_addr,
alloc_id,
size.bytes(),
align.bytes(),
slack,
);
// Remember next base address. If this allocation is zero-sized, leave a gap
// of at least 1 to avoid two allocations having the same base address.
// (The logic in `alloc_id_from_addr` assumes unique addresses, and different
// function/vtable pointers need to be distinguishable!)
global_state.next_base_addr = base_addr
.checked_add(max(size.bytes(), 1))
.ok_or_else(|| err_exhaust!(AddressSpaceFull))?;
// Even if `Size` didn't overflow, we might still have filled up the address space.
if global_state.next_base_addr > ecx.target_usize_max() {
throw_exhaust!(AddressSpaceFull);
}
// Given that `next_base_addr` increases in each allocation, pushing the
// corresponding tuple keeps `int_to_ptr_map` sorted
global_state.int_to_ptr_map.push((base_addr, alloc_id));
base_addr
}
})
}
/// Convert a relative (tcx) pointer to a Miri pointer.
pub fn ptr_from_rel_ptr(
ecx: &MiriInterpCx<'mir, 'tcx>,
fn ptr_from_rel_ptr(
&self,
ptr: Pointer<AllocId>,
tag: BorTag,
) -> InterpResult<'tcx, Pointer<Provenance>> {
let ecx = self.eval_context_ref();
let (alloc_id, offset) = ptr.into_parts(); // offset is relative (AllocId provenance)
let base_addr = GlobalStateInner::alloc_base_addr(ecx, alloc_id)?;
let base_addr = ecx.addr_from_alloc_id(alloc_id)?;
// Add offset with the right kind of pointer-overflowing arithmetic.
let dl = ecx.data_layout();
@ -234,22 +244,21 @@ impl<'mir, 'tcx> GlobalStateInner {
/// When a pointer is used for a memory access, this computes where in which allocation the
/// access is going.
pub fn ptr_get_alloc(
ecx: &MiriInterpCx<'mir, 'tcx>,
ptr: Pointer<Provenance>,
) -> Option<(AllocId, Size)> {
fn ptr_get_alloc(&self, ptr: Pointer<Provenance>) -> Option<(AllocId, Size)> {
let ecx = self.eval_context_ref();
let (tag, addr) = ptr.into_parts(); // addr is absolute (Tag provenance)
let alloc_id = if let Provenance::Concrete { alloc_id, .. } = tag {
alloc_id
} else {
// A wildcard pointer.
GlobalStateInner::alloc_id_from_addr(ecx, addr.bytes())?
ecx.alloc_id_from_addr(addr.bytes())?
};
// This cannot fail: since we already have a pointer with that provenance, rel_ptr_to_addr
// must have been called in the past.
let base_addr = GlobalStateInner::alloc_base_addr(ecx, alloc_id).unwrap();
let base_addr = ecx.addr_from_alloc_id(alloc_id).unwrap();
// Wrapping "addr - base_addr"
#[allow(clippy::cast_possible_wrap)] // we want to wrap here
@ -259,15 +268,6 @@ impl<'mir, 'tcx> GlobalStateInner {
Size::from_bytes(ecx.overflowing_signed_offset(addr.bytes(), neg_base_addr).0),
))
}
/// Shifts `addr` to make it aligned with `align` by rounding `addr` to the smallest multiple
/// of `align` that is larger or equal to `addr`
fn align_addr(addr: u64, align: u64) -> u64 {
match addr % align {
0 => addr,
rem => addr.checked_add(align).unwrap() - rem,
}
}
}
#[cfg(test)]
@ -276,7 +276,7 @@ mod tests {
#[test]
fn test_align_addr() {
assert_eq!(GlobalStateInner::align_addr(37, 4), 40);
assert_eq!(GlobalStateInner::align_addr(44, 4), 44);
assert_eq!(align_addr(37, 4), 40);
assert_eq!(align_addr(44, 4), 44);
}
}

2
src/tools/miri/src/lib.rs
View File

@ -117,7 +117,7 @@ pub use crate::eval::{
create_ecx, eval_entry, AlignmentCheck, BacktraceStyle, IsolatedOp, MiriConfig, RejectOpWith,
};
pub use crate::helpers::EvalContextExt as _;
pub use crate::intptrcast::ProvenanceMode;
pub use crate::intptrcast::{EvalContextExt as _, ProvenanceMode};
pub use crate::machine::{
AllocExtra, FrameExtra, MiriInterpCx, MiriInterpCxExt, MiriMachine, MiriMemoryKind,
PrimitiveLayouts, Provenance, ProvenanceExtra,

9
src/tools/miri/src/machine.rs
View File

@ -1149,7 +1149,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
// Value does not matter, SB is disabled
BorTag::default()
};
intptrcast::GlobalStateInner::ptr_from_rel_ptr(ecx, ptr, tag)
ecx.ptr_from_rel_ptr(ptr, tag)
}
/// Called on `usize as ptr` casts.
@ -1158,7 +1158,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
ecx: &MiriInterpCx<'mir, 'tcx>,
addr: u64,
) -> InterpResult<'tcx, Pointer<Option<Self::Provenance>>> {
intptrcast::GlobalStateInner::ptr_from_addr_cast(ecx, addr)
ecx.ptr_from_addr_cast(addr)
}
/// Called on `ptr as usize` casts.
@ -1169,8 +1169,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
ptr: Pointer<Self::Provenance>,
) -> InterpResult<'tcx> {
match ptr.provenance {
Provenance::Concrete { alloc_id, tag } =>
intptrcast::GlobalStateInner::expose_ptr(ecx, alloc_id, tag),
Provenance::Concrete { alloc_id, tag } => ecx.expose_ptr(alloc_id, tag),
Provenance::Wildcard => {
// No need to do anything for wildcard pointers as
// their provenances have already been previously exposed.
@ -1191,7 +1190,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
ecx: &MiriInterpCx<'mir, 'tcx>,
ptr: Pointer<Self::Provenance>,
) -> Option<(AllocId, Size, Self::ProvenanceExtra)> {
let rel = intptrcast::GlobalStateInner::ptr_get_alloc(ecx, ptr);
let rel = ecx.ptr_get_alloc(ptr);
rel.map(|(alloc_id, size)| {
let tag = match ptr.provenance {