-use std::cell::{Cell, RefCell};
+use std::cell::RefCell;
+use std::cmp::max;
+use std::collections::hash_map::Entry;
-use rustc::mir::interpret::{AllocId, Pointer, InterpResult};
-use rustc_mir::interpret::Memory;
-use rustc_target::abi::Size;
+use log::trace;
+use rand::Rng;
-use crate::stacked_borrows::Tag;
-use crate::Evaluator;
+use rustc_data_structures::fx::FxHashMap;
+use rustc_target::abi::{Size, HasDataLayout};
-pub type MemoryExtra = RefCell<GlobalState>;
+use crate::*;
-#[derive(Clone, Debug, Default)]
-pub struct AllocExtra {
- base_addr: Cell<Option<u64>>
-}
+pub type MemoryExtra = RefCell<GlobalState>;
#[derive(Clone, Debug)]
pub struct GlobalState {
/// This is used as a map between the address of each allocation and its `AllocId`.
/// It is always sorted
pub int_to_ptr_map: Vec<(u64, AllocId)>,
+ /// The base address for each allocation. We cannot put that into
+ /// `AllocExtra` because function pointers also have a base address, and
+ /// they do not have an `AllocExtra`.
+ /// This is the inverse of `int_to_ptr_map`.
+ pub base_addr: FxHashMap<AllocId, u64>,
/// This is used as a memory address when a new pointer is casted to an integer. It
/// is always larger than any address that was previously made part of a block.
pub next_base_addr: u64,
}
impl Default for GlobalState {
- // FIXME: Query the page size in the future
fn default() -> Self {
GlobalState {
int_to_ptr_map: Vec::default(),
- next_base_addr: 2u64.pow(16)
+ base_addr: FxHashMap::default(),
+ next_base_addr: STACK_ADDR,
}
}
}
impl<'mir, 'tcx> GlobalState {
pub fn int_to_ptr(
int: u64,
- memory: &Memory<'mir, 'tcx, Evaluator<'tcx>>,
+ memory: &Memory<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
) -> InterpResult<'tcx, Pointer<Tag>> {
let global_state = memory.extra.intptrcast.borrow();
-
- match global_state.int_to_ptr_map.binary_search_by_key(&int, |(addr, _)| *addr) {
+ let pos = global_state.int_to_ptr_map.binary_search_by_key(&int, |(addr, _)| *addr);
+
+ // The int must be in-bounds after being cast to a pointer, so we error
+ // with `CheckInAllocMsg::InboundsTest`.
+ Ok(match pos {
Ok(pos) => {
let (_, alloc_id) = global_state.int_to_ptr_map[pos];
// `int` is equal to the starting address for an allocation, the offset should be
// zero. The pointer is untagged because it was created from a cast
- Ok(Pointer::new_with_tag(alloc_id, Size::from_bytes(0), Tag::Untagged))
- },
- Err(0) => err!(DanglingPointerDeref),
+ Pointer::new_with_tag(alloc_id, Size::from_bytes(0), Tag::Untagged)
+ }
+ Err(0) => throw_ub!(DanglingIntPointer(int, CheckInAllocMsg::InboundsTest)),
Err(pos) => {
// This is the largest of the adresses smaller than `int`,
// i.e. the greatest lower bound (glb)
// This never overflows because `int >= glb`
let offset = int - glb;
// If the offset exceeds the size of the allocation, this access is illegal
- if offset <= memory.get(alloc_id)?.bytes.len() as u64 {
+ if offset <= memory.get_size_and_align(alloc_id, AllocCheck::MaybeDead)?.0.bytes() {
// This pointer is untagged because it was created from a cast
- Ok(Pointer::new_with_tag(alloc_id, Size::from_bytes(offset), Tag::Untagged))
+ Pointer::new_with_tag(alloc_id, Size::from_bytes(offset), Tag::Untagged)
} else {
- err!(DanglingPointerDeref)
- }
+ throw_ub!(DanglingIntPointer(int, CheckInAllocMsg::InboundsTest))
+ }
}
- }
+ })
}
pub fn ptr_to_int(
ptr: Pointer<Tag>,
- memory: &Memory<'mir, 'tcx, Evaluator<'tcx>>,
+ memory: &Memory<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
) -> InterpResult<'tcx, u64> {
let mut global_state = memory.extra.intptrcast.borrow_mut();
+ let global_state = &mut *global_state;
+ let id = ptr.alloc_id;
- let alloc = memory.get(ptr.alloc_id)?;
+ // There is nothing wrong with a raw pointer being cast to an integer only after
+ // it became dangling. Hence `MaybeDead`.
+ let (size, align) = memory.get_size_and_align(id, AllocCheck::MaybeDead)?;
- let base_addr = match alloc.extra.intptrcast.base_addr.get() {
- Some(base_addr) => base_addr,
- None => {
+ let base_addr = match global_state.base_addr.entry(id) {
+ Entry::Occupied(entry) => *entry.get(),
+ Entry::Vacant(entry) => {
// This allocation does not have a base address yet, pick one.
- let base_addr = Self::align_addr(global_state.next_base_addr, alloc.align.bytes());
- global_state.next_base_addr = base_addr + alloc.bytes.len() as u64;
- alloc.extra.intptrcast.base_addr.set(Some(base_addr));
+ // Leave some space to the previous allocation, to give it some chance to be less aligned.
+ let slack = {
+ let mut rng = memory.extra.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).unwrap();
+ let base_addr = Self::align_addr(base_addr, align.bytes());
+ entry.insert(base_addr);
+ trace!(
+ "Assigning base address {:#x} to allocation {:?} (slack: {}, align: {})",
+ base_addr,
+ id,
+ slack,
+ align.bytes(),
+ );
+
+ // 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.
+ global_state.next_base_addr = base_addr.checked_add(max(size.bytes(), 1)).unwrap();
// 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, ptr.alloc_id));
+ global_state.int_to_ptr_map.push((base_addr, id));
base_addr
}
};
- Ok(base_addr + ptr.offset.bytes())
+ // Sanity check that the base address is aligned.
+ debug_assert_eq!(base_addr % align.bytes(), 0);
+ // Add offset with the right kind of pointer-overflowing arithmetic.
+ let dl = memory.data_layout();
+ Ok(dl.overflowing_offset(base_addr, ptr.offset.bytes()).0)
}
/// Shifts `addr` to make it aligned with `align` by rounding `addr` to the smallest multiple
- /// of `align` that is strictly larger to `addr`
+ /// of `align` that is larger or equal to `addr`
fn align_addr(addr: u64, align: u64) -> u64 {
- addr + align - addr % align
+ match addr % align {
+ 0 => addr,
+ rem => addr.checked_add(align).unwrap() - rem,
+ }
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn test_align_addr() {
+ assert_eq!(GlobalState::align_addr(37, 4), 40);
+ assert_eq!(GlobalState::align_addr(44, 4), 44);
}
}
projects / rust.git / blobdiff