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android / platform / external / rust / crates / vm-memory / a14a572723b486483fc9dc77954f32d506b709e6 / . / src / volatile_memory.rs
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// Portions Copyright 2019 Red Hat, Inc.
//
// Copyright 2017 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the THIRT-PARTY file.
//
// SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
//! Types for volatile access to memory.
//!
//! Two of the core rules for safe rust is no data races and no aliased mutable references.
//! `VolatileRef` and `VolatileSlice`, along with types that produce those which implement
//! `VolatileMemory`, allow us to sidestep that rule by wrapping pointers that absolutely have to be
//! accessed volatile. Some systems really do need to operate on shared memory and can't have the
//! compiler reordering or eliding access because it has no visibility into what other systems are
//! doing with that hunk of memory.
//!
//! For the purposes of maintaining safety, volatile memory has some rules of its own:
//! 1. No references or slices to volatile memory (`&` or `&mut`).
//! 2. Access should always been done with a volatile read or write.
//! The First rule is because having references of any kind to memory considered volatile would
//! violate pointer aliasing. The second is because unvolatile accesses are inherently undefined if
//! done concurrently without synchronization. With volatile access we know that the compiler has
//! not reordered or elided the access.
use std::cmp::min;
use std::io::{self, Read, Write};
use std::marker::PhantomData;
use std::mem::{align_of, size_of};
use std::ptr::copy;
use std::ptr::{read_volatile, write_volatile};
use std::result;
use std::sync::atomic::Ordering;
use std::usize;
use crate::atomic_integer::AtomicInteger;
use crate::bitmap::{Bitmap, BitmapSlice, BS};
use crate::{AtomicAccess, ByteValued, Bytes};
#[cfg(all(feature = "backend-mmap", feature = "xen", unix))]
use crate::mmap_xen::{MmapXen as MmapInfo, MmapXenSlice};
#[cfg(not(feature = "xen"))]
type MmapInfo = std::marker::PhantomData<()>;
use copy_slice_impl::{copy_from_volatile_slice, copy_to_volatile_slice};
/// `VolatileMemory` related errors.
#[allow(missing_docs)]
#[derive(Debug, thiserror::Error)]
pub enum Error {
/// `addr` is out of bounds of the volatile memory slice.
#[error("address 0x{addr:x} is out of bounds")]
OutOfBounds { addr: usize },
/// Taking a slice at `base` with `offset` would overflow `usize`.
#[error("address 0x{base:x} offset by 0x{offset:x} would overflow")]
Overflow { base: usize, offset: usize },
/// Taking a slice whose size overflows `usize`.
#[error("{nelements:?} elements of size {size:?} would overflow a usize")]
TooBig { nelements: usize, size: usize },
/// Trying to obtain a misaligned reference.
#[error("address 0x{addr:x} is not aligned to {alignment:?}")]
Misaligned { addr: usize, alignment: usize },
/// Writing to memory failed
#[error("{0}")]
IOError(io::Error),
/// Incomplete read or write
#[error("only used {completed} bytes in {expected} long buffer")]
PartialBuffer { expected: usize, completed: usize },
}
/// Result of volatile memory operations.
pub type Result<T> = result::Result<T, Error>;
/// Convenience function for computing `base + offset`.
///
/// # Errors
///
/// Returns [`Err(Error::Overflow)`](enum.Error.html#variant.Overflow) in case `base + offset`
/// exceeds `usize::MAX`.
///
/// # Examples
///
/// ```
/// # use vm_memory::volatile_memory::compute_offset;
/// #
/// assert_eq!(108, compute_offset(100, 8).unwrap());
/// assert!(compute_offset(std::usize::MAX, 6).is_err());
/// ```
pub fn compute_offset(base: usize, offset: usize) -> Result<usize> {
match base.checked_add(offset) {
None => Err(Error::Overflow { base, offset }),
Some(m) => Ok(m),
}
}
/// Types that support raw volatile access to their data.
pub trait VolatileMemory {
/// Type used for dirty memory tracking.
type B: Bitmap;
/// Gets the size of this slice.
fn len(&self) -> usize;
/// Check whether the region is empty.
fn is_empty(&self) -> bool {
self.len() == 0
}
/// Returns a [`VolatileSlice`](struct.VolatileSlice.html) of `count` bytes starting at
/// `offset`.
///
/// Note that the property `get_slice(offset, count).len() == count` MUST NOT be
/// relied on for the correctness of unsafe code. This is a safe function inside of a
/// safe trait, and implementors are under no obligation to follow its documentation.
fn get_slice(&self, offset: usize, count: usize) -> Result<VolatileSlice<BS<Self::B>>>;
/// Gets a slice of memory for the entire region that supports volatile access.
fn as_volatile_slice(&self) -> VolatileSlice<BS<Self::B>> {
self.get_slice(0, self.len()).unwrap()
}
/// Gets a `VolatileRef` at `offset`.
fn get_ref<T: ByteValued>(&self, offset: usize) -> Result<VolatileRef<T, BS<Self::B>>> {
let slice = self.get_slice(offset, size_of::<T>())?;
assert_eq!(
slice.len(),
size_of::<T>(),
"VolatileMemory::get_slice(offset, count) returned slice of length != count."
);
// SAFETY: This is safe because the invariants of the constructors of VolatileSlice ensure that
// slice.addr is valid memory of size slice.len(). The assert above ensures that
// the length of the slice is exactly enough to hold one `T`. Lastly, the lifetime of the
// returned VolatileRef match that of the VolatileSlice returned by get_slice and thus the
// lifetime one `self`.
unsafe {
Ok(VolatileRef::with_bitmap(
slice.addr,
slice.bitmap,
slice.mmap,
))
}
}
/// Returns a [`VolatileArrayRef`](struct.VolatileArrayRef.html) of `n` elements starting at
/// `offset`.
fn get_array_ref<T: ByteValued>(
&self,
offset: usize,
n: usize,
) -> Result<VolatileArrayRef<T, BS<Self::B>>> {
// Use isize to avoid problems with ptr::offset and ptr::add down the line.
let nbytes = isize::try_from(n)
.ok()
.and_then(|n| n.checked_mul(size_of::<T>() as isize))
.ok_or(Error::TooBig {
nelements: n,
size: size_of::<T>(),
})?;
let slice = self.get_slice(offset, nbytes as usize)?;
assert_eq!(
slice.len(),
nbytes as usize,
"VolatileMemory::get_slice(offset, count) returned slice of length != count."
);
// SAFETY: This is safe because the invariants of the constructors of VolatileSlice ensure that
// slice.addr is valid memory of size slice.len(). The assert above ensures that
// the length of the slice is exactly enough to hold `n` instances of `T`. Lastly, the lifetime of the
// returned VolatileArrayRef match that of the VolatileSlice returned by get_slice and thus the
// lifetime one `self`.
unsafe {
Ok(VolatileArrayRef::with_bitmap(
slice.addr,
n,
slice.bitmap,
slice.mmap,
))
}
}
/// Returns a reference to an instance of `T` at `offset`.
///
/// # Safety
/// To use this safely, the caller must guarantee that there are no other
/// users of the given chunk of memory for the lifetime of the result.
///
/// # Errors
///
/// If the resulting pointer is not aligned, this method will return an
/// [`Error`](enum.Error.html).
unsafe fn aligned_as_ref<T: ByteValued>(&self, offset: usize) -> Result<&T> {
let slice = self.get_slice(offset, size_of::<T>())?;
slice.check_alignment(align_of::<T>())?;
assert_eq!(
slice.len(),
size_of::<T>(),
"VolatileMemory::get_slice(offset, count) returned slice of length != count."
);
// SAFETY: This is safe because the invariants of the constructors of VolatileSlice ensure that
// slice.addr is valid memory of size slice.len(). The assert above ensures that
// the length of the slice is exactly enough to hold one `T`.
// Dereferencing the pointer is safe because we check the alignment above, and the invariants
// of this function ensure that no aliasing pointers exist. Lastly, the lifetime of the
// returned VolatileArrayRef match that of the VolatileSlice returned by get_slice and thus the
// lifetime one `self`.
unsafe { Ok(&*(slice.addr as *const T)) }
}
/// Returns a mutable reference to an instance of `T` at `offset`. Mutable accesses performed
/// using the resulting reference are not automatically accounted for by the dirty bitmap
/// tracking functionality.
///
/// # Safety
///
/// To use this safely, the caller must guarantee that there are no other
/// users of the given chunk of memory for the lifetime of the result.
///
/// # Errors
///
/// If the resulting pointer is not aligned, this method will return an
/// [`Error`](enum.Error.html).
unsafe fn aligned_as_mut<T: ByteValued>(&self, offset: usize) -> Result<&mut T> {
let slice = self.get_slice(offset, size_of::<T>())?;
slice.check_alignment(align_of::<T>())?;
assert_eq!(
slice.len(),
size_of::<T>(),
"VolatileMemory::get_slice(offset, count) returned slice of length != count."
);
// SAFETY: This is safe because the invariants of the constructors of VolatileSlice ensure that
// slice.addr is valid memory of size slice.len(). The assert above ensures that
// the length of the slice is exactly enough to hold one `T`.
// Dereferencing the pointer is safe because we check the alignment above, and the invariants
// of this function ensure that no aliasing pointers exist. Lastly, the lifetime of the
// returned VolatileArrayRef match that of the VolatileSlice returned by get_slice and thus the
// lifetime one `self`.
unsafe { Ok(&mut *(slice.addr as *mut T)) }
}
/// Returns a reference to an instance of `T` at `offset`. Mutable accesses performed
/// using the resulting reference are not automatically accounted for by the dirty bitmap
/// tracking functionality.
///
/// # Errors
///
/// If the resulting pointer is not aligned, this method will return an
/// [`Error`](enum.Error.html).
fn get_atomic_ref<T: AtomicInteger>(&self, offset: usize) -> Result<&T> {
let slice = self.get_slice(offset, size_of::<T>())?;
slice.check_alignment(align_of::<T>())?;
assert_eq!(
slice.len(),
size_of::<T>(),
"VolatileMemory::get_slice(offset, count) returned slice of length != count."
);
// SAFETY: This is safe because the invariants of the constructors of VolatileSlice ensure that
// slice.addr is valid memory of size slice.len(). The assert above ensures that
// the length of the slice is exactly enough to hold one `T`.
// Dereferencing the pointer is safe because we check the alignment above. Lastly, the lifetime of the
// returned VolatileArrayRef match that of the VolatileSlice returned by get_slice and thus the
// lifetime one `self`.
unsafe { Ok(&*(slice.addr as *const T)) }
}
/// Returns the sum of `base` and `offset` if the resulting address is valid.
fn compute_end_offset(&self, base: usize, offset: usize) -> Result<usize> {
let mem_end = compute_offset(base, offset)?;
if mem_end > self.len() {
return Err(Error::OutOfBounds { addr: mem_end });
}
Ok(mem_end)
}
}
impl<'a> From<&'a mut [u8]> for VolatileSlice<'a, ()> {
fn from(value: &'a mut [u8]) -> Self {
// SAFETY: Since we construct the VolatileSlice from a rust slice, we know that
// the memory at addr `value as *mut u8` is valid for reads and writes (because mutable
// reference) of len `value.len()`. Since the `VolatileSlice` inherits the lifetime `'a`,
// it is not possible to access/mutate `value` while the VolatileSlice is alive.
//
// Note that it is possible for multiple aliasing sub slices of this `VolatileSlice`s to
// be created through `VolatileSlice::subslice`. This is OK, as pointers are allowed to
// alias, and it is impossible to get rust-style references from a `VolatileSlice`.
unsafe { VolatileSlice::new(value.as_mut_ptr(), value.len()) }
}
}
#[repr(C, packed)]
struct Packed<T>(T);
/// A guard to perform mapping and protect unmapping of the memory.
pub struct PtrGuard {
addr: *mut u8,
len: usize,
// This isn't used anymore, but it protects the slice from getting unmapped while in use.
// Once this goes out of scope, the memory is unmapped automatically.
#[cfg(all(feature = "xen", unix))]
_slice: MmapXenSlice,
}
#[allow(clippy::len_without_is_empty)]
impl PtrGuard {
#[allow(unused_variables)]
fn new(mmap: Option<&MmapInfo>, addr: *mut u8, prot: i32, len: usize) -> Self {
#[cfg(all(feature = "xen", unix))]
let (addr, _slice) = {
let slice = MmapInfo::mmap(mmap, addr, prot, len);
(slice.addr(), slice)
};
Self {
addr,
len,
#[cfg(all(feature = "xen", unix))]
_slice,
}
}
fn read(mmap: Option<&MmapInfo>, addr: *mut u8, len: usize) -> Self {
Self::new(mmap, addr, libc::PROT_READ, len)
}
/// Returns a non-mutable pointer to the beginning of the slice.
pub fn as_ptr(&self) -> *const u8 {
self.addr
}
/// Gets the length of the mapped region.
pub fn len(&self) -> usize {
self.len
}
}
/// A mutable guard to perform mapping and protect unmapping of the memory.
pub struct PtrGuardMut(PtrGuard);
#[allow(clippy::len_without_is_empty)]
impl PtrGuardMut {
fn write(mmap: Option<&MmapInfo>, addr: *mut u8, len: usize) -> Self {
Self(PtrGuard::new(mmap, addr, libc::PROT_WRITE, len))
}
/// Returns a mutable pointer to the beginning of the slice. Mutable accesses performed
/// using the resulting pointer are not automatically accounted for by the dirty bitmap
/// tracking functionality.
pub fn as_ptr(&self) -> *mut u8 {
self.0.addr
}
/// Gets the length of the mapped region.
pub fn len(&self) -> usize {
self.0.len
}
}
/// A slice of raw memory that supports volatile access.
#[derive(Clone, Copy, Debug)]
pub struct VolatileSlice<'a, B = ()> {
addr: *mut u8,
size: usize,
bitmap: B,
mmap: Option<&'a MmapInfo>,
}
impl<'a> VolatileSlice<'a, ()> {
/// Creates a slice of raw memory that must support volatile access.
///
/// # Safety
///
/// To use this safely, the caller must guarantee that the memory at `addr` is `size` bytes long
/// and is available for the duration of the lifetime of the new `VolatileSlice`. The caller
/// must also guarantee that all other users of the given chunk of memory are using volatile
/// accesses.
pub unsafe fn new(addr: *mut u8, size: usize) -> VolatileSlice<'a> {
Self::with_bitmap(addr, size, (), None)
}
}
impl<'a, B: BitmapSlice> VolatileSlice<'a, B> {
/// Creates a slice of raw memory that must support volatile access, and uses the provided
/// `bitmap` object for dirty page tracking.
///
/// # Safety
///
/// To use this safely, the caller must guarantee that the memory at `addr` is `size` bytes long
/// and is available for the duration of the lifetime of the new `VolatileSlice`. The caller
/// must also guarantee that all other users of the given chunk of memory are using volatile
/// accesses.
pub unsafe fn with_bitmap(
addr: *mut u8,
size: usize,
bitmap: B,
mmap: Option<&'a MmapInfo>,
) -> VolatileSlice<'a, B> {
VolatileSlice {
addr,
size,
bitmap,
mmap,
}
}
/// Returns a pointer to the beginning of the slice. Mutable accesses performed
/// using the resulting pointer are not automatically accounted for by the dirty bitmap
/// tracking functionality.
#[deprecated(
since = "0.12.1",
note = "Use `.ptr_guard()` or `.ptr_guard_mut()` instead"
)]
#[cfg(not(all(feature = "xen", unix)))]
pub fn as_ptr(&self) -> *mut u8 {
self.addr
}
/// Returns a guard for the pointer to the underlying memory.
pub fn ptr_guard(&self) -> PtrGuard {
PtrGuard::read(self.mmap, self.addr, self.len())
}
/// Returns a mutable guard for the pointer to the underlying memory.
pub fn ptr_guard_mut(&self) -> PtrGuardMut {
PtrGuardMut::write(self.mmap, self.addr, self.len())
}
/// Gets the size of this slice.
pub fn len(&self) -> usize {
self.size
}
/// Checks if the slice is empty.
pub fn is_empty(&self) -> bool {
self.size == 0
}
/// Borrows the inner `BitmapSlice`.
pub fn bitmap(&self) -> &B {
&self.bitmap
}
/// Divides one slice into two at an index.
///
/// # Example
///
/// ```
/// # use vm_memory::{VolatileMemory, VolatileSlice};
/// #
/// # // Create a buffer
/// # let mut mem = [0u8; 32];
/// #
/// # // Get a `VolatileSlice` from the buffer
/// let vslice = VolatileSlice::from(&mut mem[..]);
///
/// let (start, end) = vslice.split_at(8).expect("Could not split VolatileSlice");
/// assert_eq!(8, start.len());
/// assert_eq!(24, end.len());
/// ```
pub fn split_at(&self, mid: usize) -> Result<(Self, Self)> {
let end = self.offset(mid)?;
let start =
// SAFETY: safe because self.offset() already checked the bounds
unsafe { VolatileSlice::with_bitmap(self.addr, mid, self.bitmap.clone(), self.mmap) };
Ok((start, end))
}
/// Returns a subslice of this [`VolatileSlice`](struct.VolatileSlice.html) starting at
/// `offset` with `count` length.
///
/// The returned subslice is a copy of this slice with the address increased by `offset` bytes
/// and the size set to `count` bytes.
pub fn subslice(&self, offset: usize, count: usize) -> Result<Self> {
let _ = self.compute_end_offset(offset, count)?;
// SAFETY: This is safe because the pointer is range-checked by compute_end_offset, and
// the lifetime is the same as the original slice.
unsafe {
Ok(VolatileSlice::with_bitmap(
self.addr.add(offset),
count,
self.bitmap.slice_at(offset),
self.mmap,
))
}
}
/// Returns a subslice of this [`VolatileSlice`](struct.VolatileSlice.html) starting at
/// `offset`.
///
/// The returned subslice is a copy of this slice with the address increased by `count` bytes
/// and the size reduced by `count` bytes.
pub fn offset(&self, count: usize) -> Result<VolatileSlice<'a, B>> {
let new_addr = (self.addr as usize)
.checked_add(count)
.ok_or(Error::Overflow {
base: self.addr as usize,
offset: count,
})?;
let new_size = self
.size
.checked_sub(count)
.ok_or(Error::OutOfBounds { addr: new_addr })?;
// SAFETY: Safe because the memory has the same lifetime and points to a subset of the
// memory of the original slice.
unsafe {
Ok(VolatileSlice::with_bitmap(
self.addr.add(count),
new_size,
self.bitmap.slice_at(count),
self.mmap,
))
}
}
/// Copies as many elements of type `T` as possible from this slice to `buf`.
///
/// Copies `self.len()` or `buf.len()` times the size of `T` bytes, whichever is smaller,
/// to `buf`. The copy happens from smallest to largest address in `T` sized chunks
/// using volatile reads.
///
/// # Examples
///
/// ```
/// # use vm_memory::{VolatileMemory, VolatileSlice};
/// #
/// let mut mem = [0u8; 32];
/// let vslice = VolatileSlice::from(&mut mem[..]);
/// let mut buf = [5u8; 16];
/// let res = vslice.copy_to(&mut buf[..]);
///
/// assert_eq!(16, res);
/// for &v in &buf[..] {
/// assert_eq!(v, 0);
/// }
/// ```
pub fn copy_to<T>(&self, buf: &mut [T]) -> usize
where
T: ByteValued,
{
// A fast path for u8/i8
if size_of::<T>() == 1 {
let total = buf.len().min(self.len());
// SAFETY:
// - dst is valid for writes of at least `total`, since total <= buf.len()
// - src is valid for reads of at least `total` as total <= self.len()
// - The regions are non-overlapping as `src` points to guest memory and `buf` is
// a slice and thus has to live outside of guest memory (there can be more slices to
// guest memory without violating rust's aliasing rules)
// - size is always a multiple of alignment, so treating *mut T as *mut u8 is fine
unsafe { copy_from_volatile_slice(buf.as_mut_ptr() as *mut u8, self, total) }
} else {
let count = self.size / size_of::<T>();
let source = self.get_array_ref::<T>(0, count).unwrap();
source.copy_to(buf)
}
}
/// Copies as many bytes as possible from this slice to the provided `slice`.
///
/// The copies happen in an undefined order.
///
/// # Examples
///
/// ```
/// # use vm_memory::{VolatileMemory, VolatileSlice};
/// #
/// # // Create a buffer
/// # let mut mem = [0u8; 32];
/// #
/// # // Get a `VolatileSlice` from the buffer
/// # let vslice = VolatileSlice::from(&mut mem[..]);
/// #
/// vslice.copy_to_volatile_slice(
/// vslice
/// .get_slice(16, 16)
/// .expect("Could not get VolatileSlice"),
/// );
/// ```
pub fn copy_to_volatile_slice<S: BitmapSlice>(&self, slice: VolatileSlice<S>) {
// SAFETY: Safe because the pointers are range-checked when the slices
// are created, and they never escape the VolatileSlices.
// FIXME: ... however, is it really okay to mix non-volatile
// operations such as copy with read_volatile and write_volatile?
unsafe {
let count = min(self.size, slice.size);
copy(self.addr, slice.addr, count);
slice.bitmap.mark_dirty(0, count);
}
}
/// Copies as many elements of type `T` as possible from `buf` to this slice.
///
/// The copy happens from smallest to largest address in `T` sized chunks using volatile writes.
///
/// # Examples
///
/// ```
/// # use vm_memory::{VolatileMemory, VolatileSlice};
/// #
/// let mut mem = [0u8; 32];
/// let vslice = VolatileSlice::from(&mut mem[..]);
///
/// let buf = [5u8; 64];
/// vslice.copy_from(&buf[..]);
///
/// for i in 0..4 {
/// let val = vslice
/// .get_ref::<u32>(i * 4)
/// .expect("Could not get value")
/// .load();
/// assert_eq!(val, 0x05050505);
/// }
/// ```
pub fn copy_from<T>(&self, buf: &[T])
where
T: ByteValued,
{
// A fast path for u8/i8
if size_of::<T>() == 1 {
let total = buf.len().min(self.len());
// SAFETY:
// - dst is valid for writes of at least `total`, since total <= self.len()
// - src is valid for reads of at least `total` as total <= buf.len()
// - The regions are non-overlapping as `dst` points to guest memory and `buf` is
// a slice and thus has to live outside of guest memory (there can be more slices to
// guest memory without violating rust's aliasing rules)
// - size is always a multiple of alignment, so treating *mut T as *mut u8 is fine
unsafe { copy_to_volatile_slice(self, buf.as_ptr() as *const u8, total) };
} else {
let count = self.size / size_of::<T>();
// It's ok to use unwrap here because `count` was computed based on the current
// length of `self`.
let dest = self.get_array_ref::<T>(0, count).unwrap();
// No need to explicitly call `mark_dirty` after this call because
// `VolatileArrayRef::copy_from` already takes care of that.
dest.copy_from(buf);
};
}
/// Checks if the current slice is aligned at `alignment` bytes.
fn check_alignment(&self, alignment: usize) -> Result<()> {
// Check that the desired alignment is a power of two.
debug_assert!((alignment & (alignment - 1)) == 0);
if ((self.addr as usize) & (alignment - 1)) != 0 {
return Err(Error::Misaligned {
addr: self.addr as usize,
alignment,
});
}
Ok(())
}
}
impl<B: BitmapSlice> Bytes<usize> for VolatileSlice<'_, B> {
type E = Error;
/// # Examples
/// * Write a slice of size 5 at offset 1020 of a 1024-byte `VolatileSlice`.
///
/// ```
/// # use vm_memory::{Bytes, VolatileMemory, VolatileSlice};
/// #
/// let mut mem = [0u8; 1024];
/// let vslice = VolatileSlice::from(&mut mem[..]);
/// let res = vslice.write(&[1, 2, 3, 4, 5], 1020);
///
/// assert!(res.is_ok());
/// assert_eq!(res.unwrap(), 4);
/// ```
fn write(&self, buf: &[u8], addr: usize) -> Result<usize> {
if buf.is_empty() {
return Ok(0);
}
if addr >= self.size {
return Err(Error::OutOfBounds { addr });
}
let total = buf.len().min(self.len() - addr);
let dst = self.subslice(addr, total)?;
// SAFETY:
// We check above that `addr` is a valid offset within this volatile slice, and by
// the invariants of `VolatileSlice::new`, this volatile slice points to contiguous
// memory of length self.len(). Furthermore, both src and dst of the call to
// copy_to_volatile_slice are valid for reads and writes respectively of length `total`
// since total is the minimum of lengths of the memory areas pointed to. The areas do not
// overlap, since `dst` is inside guest memory, and buf is a slice (no slices to guest
// memory are possible without violating rust's aliasing rules).
Ok(unsafe { copy_to_volatile_slice(&dst, buf.as_ptr(), total) })
}
/// # Examples
/// * Read a slice of size 16 at offset 1010 of a 1024-byte `VolatileSlice`.
///
/// ```
/// # use vm_memory::{Bytes, VolatileMemory, VolatileSlice};
/// #
/// let mut mem = [0u8; 1024];
/// let vslice = VolatileSlice::from(&mut mem[..]);
/// let buf = &mut [0u8; 16];
/// let res = vslice.read(buf, 1010);
///
/// assert!(res.is_ok());
/// assert_eq!(res.unwrap(), 14);
/// ```
fn read(&self, buf: &mut [u8], addr: usize) -> Result<usize> {
if buf.is_empty() {
return Ok(0);
}
if addr >= self.size {
return Err(Error::OutOfBounds { addr });
}
let total = buf.len().min(self.len() - addr);
let src = self.subslice(addr, total)?;
// SAFETY:
// We check above that `addr` is a valid offset within this volatile slice, and by
// the invariants of `VolatileSlice::new`, this volatile slice points to contiguous
// memory of length self.len(). Furthermore, both src and dst of the call to
// copy_from_volatile_slice are valid for reads and writes respectively of length `total`
// since total is the minimum of lengths of the memory areas pointed to. The areas do not
// overlap, since `dst` is inside guest memory, and buf is a slice (no slices to guest
// memory are possible without violating rust's aliasing rules).
unsafe { Ok(copy_from_volatile_slice(buf.as_mut_ptr(), &src, total)) }
}
/// # Examples
/// * Write a slice at offset 256.
///
/// ```
/// # use vm_memory::{Bytes, VolatileMemory, VolatileSlice};
/// #
/// # // Create a buffer
/// # let mut mem = [0u8; 1024];
/// #
/// # // Get a `VolatileSlice` from the buffer
/// # let vslice = VolatileSlice::from(&mut mem[..]);
/// #
/// let res = vslice.write_slice(&[1, 2, 3, 4, 5], 256);
///
/// assert!(res.is_ok());
/// assert_eq!(res.unwrap(), ());
/// ```
fn write_slice(&self, buf: &[u8], addr: usize) -> Result<()> {
// `mark_dirty` called within `self.write`.
let len = self.write(buf, addr)?;
if len != buf.len() {
return Err(Error::PartialBuffer {
expected: buf.len(),
completed: len,
});
}
Ok(())
}
/// # Examples
/// * Read a slice of size 16 at offset 256.
///
/// ```
/// # use vm_memory::{Bytes, VolatileMemory, VolatileSlice};
/// #
/// # // Create a buffer
/// # let mut mem = [0u8; 1024];
/// #
/// # // Get a `VolatileSlice` from the buffer
/// # let vslice = VolatileSlice::from(&mut mem[..]);
/// #
/// let buf = &mut [0u8; 16];
/// let res = vslice.read_slice(buf, 256);
///
/// assert!(res.is_ok());
/// ```
fn read_slice(&self, buf: &mut [u8], addr: usize) -> Result<()> {
let len = self.read(buf, addr)?;
if len != buf.len() {
return Err(Error::PartialBuffer {
expected: buf.len(),
completed: len,
});
}
Ok(())
}
/// # Examples
///
/// * Read bytes from /dev/urandom
///
/// ```
/// # use vm_memory::{Bytes, VolatileMemory, VolatileSlice};
/// # use std::fs::File;
/// # use std::path::Path;
/// #
/// # if cfg!(unix) {
/// # let mut mem = [0u8; 1024];
/// # let vslice = VolatileSlice::from(&mut mem[..]);
/// let mut file = File::open(Path::new("/dev/urandom")).expect("Could not open /dev/urandom");
///
/// vslice
/// .read_from(32, &mut file, 128)
/// .expect("Could not read bytes from file into VolatileSlice");
///
/// let rand_val: u32 = vslice
/// .read_obj(40)
/// .expect("Could not read value from VolatileSlice");
/// # }
/// ```
fn read_from<F>(&self, addr: usize, src: &mut F, count: usize) -> Result<usize>
where
F: Read,
{
let _ = self.compute_end_offset(addr, count)?;
let mut dst = vec![0; count];
let bytes_read = loop {
match src.read(&mut dst) {
Ok(n) => break n,
Err(ref e) if e.kind() == std::io::ErrorKind::Interrupted => continue,
Err(e) => return Err(Error::IOError(e)),
}
};
// There is no guarantee that the read implementation is well-behaved, see the docs for
// Read::read.
assert!(bytes_read <= count);
let slice = self.subslice(addr, bytes_read)?;
// SAFETY: We have checked via compute_end_offset that accessing the specified
// region of guest memory is valid. We asserted that the value returned by `read` is between
// 0 and count (the length of the buffer passed to it), and that the
// regions don't overlap because we allocated the Vec outside of guest memory.
Ok(unsafe { copy_to_volatile_slice(&slice, dst.as_ptr(), bytes_read) })
}
/// # Examples
///
/// * Read bytes from /dev/urandom
///
/// ```
/// # use vm_memory::{Bytes, VolatileMemory, VolatileSlice};
/// # use std::fs::File;
/// # use std::path::Path;
/// #
/// # if cfg!(unix) {
/// # let mut mem = [0u8; 1024];
/// # let vslice = VolatileSlice::from(&mut mem[..]);
/// let mut file = File::open(Path::new("/dev/urandom")).expect("Could not open /dev/urandom");
///
/// vslice
/// .read_exact_from(32, &mut file, 128)
/// .expect("Could not read bytes from file into VolatileSlice");
///
/// let rand_val: u32 = vslice
/// .read_obj(40)
/// .expect("Could not read value from VolatileSlice");
/// # }
/// ```
fn read_exact_from<F>(&self, addr: usize, src: &mut F, count: usize) -> Result<()>
where
F: Read,
{
let _ = self.compute_end_offset(addr, count)?;
let mut dst = vec![0; count];
// Read into buffer that can be copied into guest memory
src.read_exact(&mut dst).map_err(Error::IOError)?;
let slice = self.subslice(addr, count)?;
// SAFETY: We have checked via compute_end_offset that accessing the specified
// region of guest memory is valid. We know that `dst` has len `count`, and that the
// regions don't overlap because we allocated the Vec outside of guest memory
unsafe { copy_to_volatile_slice(&slice, dst.as_ptr(), count) };
Ok(())
}
/// # Examples
///
/// * Write 128 bytes to /dev/null
///
/// ```
/// # use vm_memory::{Bytes, VolatileMemory, VolatileSlice};
/// # use std::fs::OpenOptions;
/// # use std::path::Path;
/// #
/// # if cfg!(unix) {
/// # let mut mem = [0u8; 1024];
/// # let vslice = VolatileSlice::from(&mut mem[..]);
/// let mut file = OpenOptions::new()
/// .write(true)
/// .open("/dev/null")
/// .expect("Could not open /dev/null");
///
/// vslice
/// .write_to(32, &mut file, 128)
/// .expect("Could not write value from VolatileSlice to /dev/null");
/// # }
/// ```
fn write_to<F>(&self, addr: usize, dst: &mut F, count: usize) -> Result<usize>
where
F: Write,
{
let _ = self.compute_end_offset(addr, count)?;
let mut src = Vec::with_capacity(count);
let slice = self.subslice(addr, count)?;
// SAFETY: We checked the addr and count so accessing the slice is safe.
// It is safe to read from volatile memory. The Vec has capacity for exactly `count`
// many bytes, and the memory regions pointed to definitely do not overlap, as we
// allocated src outside of guest memory.
// The call to set_len is safe because the bytes between 0 and count have been initialized
// via copying from guest memory, and the Vec's capacity is `count`
unsafe {
copy_from_volatile_slice(src.as_mut_ptr(), &slice, count);
src.set_len(count);
}
loop {
match dst.write(&src) {
Ok(n) => break Ok(n),
Err(ref e) if e.kind() == std::io::ErrorKind::Interrupted => continue,
Err(e) => break Err(Error::IOError(e)),
}
}
}
/// # Examples
///
/// * Write 128 bytes to /dev/null
///
/// ```
/// # use vm_memory::{Bytes, VolatileMemory, VolatileSlice};
/// # use std::fs::OpenOptions;
/// # use std::path::Path;
/// #
/// # if cfg!(unix) {
/// # let mut mem = [0u8; 1024];
/// # let vslice = VolatileSlice::from(&mut mem[..]);
/// let mut file = OpenOptions::new()
/// .write(true)
/// .open("/dev/null")
/// .expect("Could not open /dev/null");
///
/// vslice
/// .write_all_to(32, &mut file, 128)
/// .expect("Could not write value from VolatileSlice to /dev/null");
/// # }
/// ```
fn write_all_to<F>(&self, addr: usize, dst: &mut F, count: usize) -> Result<()>
where
F: Write,
{
let _ = self.compute_end_offset(addr, count)?;
let mut src = Vec::with_capacity(count);
let slice = self.subslice(addr, count)?;
// SAFETY: We checked the addr and count so accessing the slice is safe.
// It is safe to read from volatile memory. The Vec has capacity for exactly `count`
// many bytes, and the memory regions pointed to definitely do not overlap, as we
// allocated src outside of guest memory.
// The call to set_len is safe because the bytes between 0 and count have been initialized
// via copying from guest memory, and the Vec's capacity is `count`
unsafe {
copy_from_volatile_slice(src.as_mut_ptr(), &slice, count);
src.set_len(count);
}
dst.write_all(&src).map_err(Error::IOError)?;
Ok(())
}
fn store<T: AtomicAccess>(&self, val: T, addr: usize, order: Ordering) -> Result<()> {
self.get_atomic_ref::<T::A>(addr).map(|r| {
r.store(val.into(), order);
self.bitmap.mark_dirty(addr, size_of::<T>())
})
}
fn load<T: AtomicAccess>(&self, addr: usize, order: Ordering) -> Result<T> {
self.get_atomic_ref::<T::A>(addr)
.map(|r| r.load(order).into())
}
}
impl<B: BitmapSlice> VolatileMemory for VolatileSlice<'_, B> {
type B = B;
fn len(&self) -> usize {
self.size
}
fn get_slice(&self, offset: usize, count: usize) -> Result<VolatileSlice<B>> {
let _ = self.compute_end_offset(offset, count)?;
Ok(
// SAFETY: This is safe because the pointer is range-checked by compute_end_offset, and
// the lifetime is the same as self.
unsafe {
VolatileSlice::with_bitmap(
self.addr.add(offset),
count,
self.bitmap.slice_at(offset),
self.mmap,
)
},
)
}
}
/// A memory location that supports volatile access to an instance of `T`.
///
/// # Examples
///
/// ```
/// # use vm_memory::VolatileRef;
/// #
/// let mut v = 5u32;
/// let v_ref = unsafe { VolatileRef::new(&mut v as *mut u32 as *mut u8) };
///
/// assert_eq!(v, 5);
/// assert_eq!(v_ref.load(), 5);
/// v_ref.store(500);
/// assert_eq!(v, 500);
/// ```
#[derive(Clone, Copy, Debug)]
pub struct VolatileRef<'a, T, B = ()> {
addr: *mut Packed<T>,
bitmap: B,
mmap: Option<&'a MmapInfo>,
}
impl<'a, T> VolatileRef<'a, T, ()>
where
T: ByteValued,
{
/// Creates a [`VolatileRef`](struct.VolatileRef.html) to an instance of `T`.
///
/// # Safety
///
/// To use this safely, the caller must guarantee that the memory at `addr` is big enough for a
/// `T` and is available for the duration of the lifetime of the new `VolatileRef`. The caller
/// must also guarantee that all other users of the given chunk of memory are using volatile
/// accesses.
pub unsafe fn new(addr: *mut u8) -> Self {
Self::with_bitmap(addr, (), None)
}
}
#[allow(clippy::len_without_is_empty)]
impl<'a, T, B> VolatileRef<'a, T, B>
where
T: ByteValued,
B: BitmapSlice,
{
/// Creates a [`VolatileRef`](struct.VolatileRef.html) to an instance of `T`, using the
/// provided `bitmap` object for dirty page tracking.
///
/// # Safety
///
/// To use this safely, the caller must guarantee that the memory at `addr` is big enough for a
/// `T` and is available for the duration of the lifetime of the new `VolatileRef`. The caller
/// must also guarantee that all other users of the given chunk of memory are using volatile
/// accesses.
pub unsafe fn with_bitmap(addr: *mut u8, bitmap: B, mmap: Option<&'a MmapInfo>) -> Self {
VolatileRef {
addr: addr as *mut Packed<T>,
bitmap,
mmap,
}
}
/// Returns a pointer to the underlying memory. Mutable accesses performed
/// using the resulting pointer are not automatically accounted for by the dirty bitmap
/// tracking functionality.
#[deprecated(
since = "0.12.1",
note = "Use `.ptr_guard()` or `.ptr_guard_mut()` instead"
)]
#[cfg(not(all(feature = "xen", unix)))]
pub fn as_ptr(&self) -> *mut u8 {
self.addr as *mut u8
}
/// Returns a guard for the pointer to the underlying memory.
pub fn ptr_guard(&self) -> PtrGuard {
PtrGuard::read(self.mmap, self.addr as *mut u8, self.len())
}
/// Returns a mutable guard for the pointer to the underlying memory.
pub fn ptr_guard_mut(&self) -> PtrGuardMut {
PtrGuardMut::write(self.mmap, self.addr as *mut u8, self.len())
}
/// Gets the size of the referenced type `T`.
///
/// # Examples
///
/// ```
/// # use std::mem::size_of;
/// # use vm_memory::VolatileRef;
/// #
/// let v_ref = unsafe { VolatileRef::<u32>::new(0 as *mut _) };
/// assert_eq!(v_ref.len(), size_of::<u32>() as usize);
/// ```
pub fn len(&self) -> usize {
size_of::<T>()
}
/// Borrows the inner `BitmapSlice`.
pub fn bitmap(&self) -> &B {
&self.bitmap
}
/// Does a volatile write of the value `v` to the address of this ref.
#[inline(always)]
pub fn store(&self, v: T) {
let guard = self.ptr_guard_mut();
// SAFETY: Safe because we checked the address and size when creating this VolatileRef.
unsafe { write_volatile(guard.as_ptr() as *mut Packed<T>, Packed::<T>(v)) };
self.bitmap.mark_dirty(0, self.len())
}
/// Does a volatile read of the value at the address of this ref.
#[inline(always)]
pub fn load(&self) -> T {
let guard = self.ptr_guard();
// SAFETY: Safe because we checked the address and size when creating this VolatileRef.
// For the purposes of demonstrating why read_volatile is necessary, try replacing the code
// in this function with the commented code below and running `cargo test --release`.
// unsafe { *(self.addr as *const T) }
unsafe { read_volatile(guard.as_ptr() as *const Packed<T>).0 }
}
/// Converts this to a [`VolatileSlice`](struct.VolatileSlice.html) with the same size and
/// address.
pub fn to_slice(&self) -> VolatileSlice<'a, B> {
// SAFETY: Safe because we checked the address and size when creating this VolatileRef.
unsafe {
VolatileSlice::with_bitmap(
self.addr as *mut u8,
size_of::<T>(),
self.bitmap.clone(),
self.mmap,
)
}
}
}
/// A memory location that supports volatile access to an array of elements of type `T`.
///
/// # Examples
///
/// ```
/// # use vm_memory::VolatileArrayRef;
/// #
/// let mut v = [5u32; 1];
/// let v_ref = unsafe { VolatileArrayRef::new(&mut v[0] as *mut u32 as *mut u8, v.len()) };
///
/// assert_eq!(v[0], 5);
/// assert_eq!(v_ref.load(0), 5);
/// v_ref.store(0, 500);
/// assert_eq!(v[0], 500);
/// ```
#[derive(Clone, Copy, Debug)]
pub struct VolatileArrayRef<'a, T, B = ()> {
addr: *mut u8,
nelem: usize,
bitmap: B,
phantom: PhantomData<&'a T>,
mmap: Option<&'a MmapInfo>,
}
impl<'a, T> VolatileArrayRef<'a, T>
where
T: ByteValued,
{
/// Creates a [`VolatileArrayRef`](struct.VolatileArrayRef.html) to an array of elements of
/// type `T`.
///
/// # Safety
///
/// To use this safely, the caller must guarantee that the memory at `addr` is big enough for
/// `nelem` values of type `T` and is available for the duration of the lifetime of the new
/// `VolatileRef`. The caller must also guarantee that all other users of the given chunk of
/// memory are using volatile accesses.
pub unsafe fn new(addr: *mut u8, nelem: usize) -> Self {
Self::with_bitmap(addr, nelem, (), None)
}
}
impl<'a, T, B> VolatileArrayRef<'a, T, B>
where
T: ByteValued,
B: BitmapSlice,
{
/// Creates a [`VolatileArrayRef`](struct.VolatileArrayRef.html) to an array of elements of
/// type `T`, using the provided `bitmap` object for dirty page tracking.
///
/// # Safety
///
/// To use this safely, the caller must guarantee that the memory at `addr` is big enough for
/// `nelem` values of type `T` and is available for the duration of the lifetime of the new
/// `VolatileRef`. The caller must also guarantee that all other users of the given chunk of
/// memory are using volatile accesses.
pub unsafe fn with_bitmap(
addr: *mut u8,
nelem: usize,
bitmap: B,
mmap: Option<&'a MmapInfo>,
) -> Self {
VolatileArrayRef {
addr,
nelem,
bitmap,
phantom: PhantomData,
mmap,
}
}
/// Returns `true` if this array is empty.
///
/// # Examples
///
/// ```
/// # use vm_memory::VolatileArrayRef;
/// #
/// let v_array = unsafe { VolatileArrayRef::<u32>::new(0 as *mut _, 0) };
/// assert!(v_array.is_empty());
/// ```
pub fn is_empty(&self) -> bool {
self.nelem == 0
}
/// Returns the number of elements in the array.
///
/// # Examples
///
/// ```
/// # use vm_memory::VolatileArrayRef;
/// #
/// # let v_array = unsafe { VolatileArrayRef::<u32>::new(0 as *mut _, 1) };
/// assert_eq!(v_array.len(), 1);
/// ```
pub fn len(&self) -> usize {
self.nelem
}
/// Returns the size of `T`.
///
/// # Examples
///
/// ```
/// # use std::mem::size_of;
/// # use vm_memory::VolatileArrayRef;
/// #
/// let v_ref = unsafe { VolatileArrayRef::<u32>::new(0 as *mut _, 0) };
/// assert_eq!(v_ref.element_size(), size_of::<u32>() as usize);
/// ```
pub fn element_size(&self) -> usize {
size_of::<T>()
}
/// Returns a pointer to the underlying memory. Mutable accesses performed
/// using the resulting pointer are not automatically accounted for by the dirty bitmap
/// tracking functionality.
#[deprecated(
since = "0.12.1",
note = "Use `.ptr_guard()` or `.ptr_guard_mut()` instead"
)]
#[cfg(not(all(feature = "xen", unix)))]
pub fn as_ptr(&self) -> *mut u8 {
self.addr
}
/// Returns a guard for the pointer to the underlying memory.
pub fn ptr_guard(&self) -> PtrGuard {
PtrGuard::read(self.mmap, self.addr, self.len())
}
/// Returns a mutable guard for the pointer to the underlying memory.
pub fn ptr_guard_mut(&self) -> PtrGuardMut {
PtrGuardMut::write(self.mmap, self.addr, self.len())
}
/// Borrows the inner `BitmapSlice`.
pub fn bitmap(&self) -> &B {
&self.bitmap
}
/// Converts this to a `VolatileSlice` with the same size and address.
pub fn to_slice(&self) -> VolatileSlice<'a, B> {
// SAFETY: Safe as long as the caller validated addr when creating this object.
unsafe {
VolatileSlice::with_bitmap(
self.addr,
self.nelem * self.element_size(),
self.bitmap.clone(),
self.mmap,
)
}
}
/// Does a volatile read of the element at `index`.
///
/// # Panics
///
/// Panics if `index` is less than the number of elements of the array to which `&self` points.
pub fn ref_at(&self, index: usize) -> VolatileRef<'a, T, B> {
assert!(index < self.nelem);
// SAFETY: Safe because the memory has the same lifetime and points to a subset of the
// memory of the VolatileArrayRef.
unsafe {
// byteofs must fit in an isize as it was checked in get_array_ref.
let byteofs = (self.element_size() * index) as isize;
let ptr = self.addr.offset(byteofs);
VolatileRef::with_bitmap(ptr, self.bitmap.slice_at(byteofs as usize), self.mmap)
}
}
/// Does a volatile read of the element at `index`.
pub fn load(&self, index: usize) -> T {
self.ref_at(index).load()
}
/// Does a volatile write of the element at `index`.
pub fn store(&self, index: usize, value: T) {
// The `VolatileRef::store` call below implements the required dirty bitmap tracking logic,
// so no need to do that in this method as well.
self.ref_at(index).store(value)
}
/// Copies as many elements of type `T` as possible from this array to `buf`.
///
/// Copies `self.len()` or `buf.len()` times the size of `T` bytes, whichever is smaller,
/// to `buf`. The copy happens from smallest to largest address in `T` sized chunks
/// using volatile reads.
///
/// # Examples
///
/// ```
/// # use vm_memory::VolatileArrayRef;
/// #
/// let mut v = [0u8; 32];
/// let v_ref = unsafe { VolatileArrayRef::new(v.as_mut_ptr(), v.len()) };
///
/// let mut buf = [5u8; 16];
/// v_ref.copy_to(&mut buf[..]);
/// for &v in &buf[..] {
/// assert_eq!(v, 0);
/// }
/// ```
pub fn copy_to(&self, buf: &mut [T]) -> usize {
// A fast path for u8/i8
if size_of::<T>() == 1 {
let source = self.to_slice();
let total = buf.len().min(source.len());
// SAFETY:
// - dst is valid for writes of at least `total`, since total <= buf.len()
// - src is valid for reads of at least `total` as total <= source.len()
// - The regions are non-overlapping as `src` points to guest memory and `buf` is
// a slice and thus has to live outside of guest memory (there can be more slices to
// guest memory without violating rust's aliasing rules)
// - size is always a multiple of alignment, so treating *mut T as *mut u8 is fine
return unsafe {
copy_from_volatile_slice(buf.as_mut_ptr() as *mut u8, &source, total)
};
}
let guard = self.ptr_guard();
let mut ptr = guard.as_ptr() as *const Packed<T>;
let start = ptr;
for v in buf.iter_mut().take(self.len()) {
// SAFETY: read_volatile is safe because the pointers are range-checked when
// the slices are created, and they never escape the VolatileSlices.
// ptr::add is safe because get_array_ref() validated that
// size_of::<T>() * self.len() fits in an isize.
unsafe {
*v = read_volatile(ptr).0;
ptr = ptr.add(1);
}
}
// SAFETY: It is guaranteed that start and ptr point to the regions of the same slice.
unsafe { ptr.offset_from(start) as usize }
}
/// Copies as many bytes as possible from this slice to the provided `slice`.
///
/// The copies happen in an undefined order.
///
/// # Examples
///
/// ```
/// # use vm_memory::VolatileArrayRef;
/// #
/// let mut v = [0u8; 32];
/// let v_ref = unsafe { VolatileArrayRef::<u8>::new(v.as_mut_ptr(), v.len()) };
/// let mut buf = [5u8; 16];
/// let v_ref2 = unsafe { VolatileArrayRef::<u8>::new(buf.as_mut_ptr(), buf.len()) };
///
/// v_ref.copy_to_volatile_slice(v_ref2.to_slice());
/// for &v in &buf[..] {
/// assert_eq!(v, 0);
/// }
/// ```
pub fn copy_to_volatile_slice<S: BitmapSlice>(&self, slice: VolatileSlice<S>) {
// SAFETY: Safe because the pointers are range-checked when the slices
// are created, and they never escape the VolatileSlices.
// FIXME: ... however, is it really okay to mix non-volatile
// operations such as copy with read_volatile and write_volatile?
unsafe {
let count = min(self.len() * self.element_size(), slice.size);
copy(self.addr, slice.addr, count);
slice.bitmap.mark_dirty(0, count);
}
}
/// Copies as many elements of type `T` as possible from `buf` to this slice.
///
/// Copies `self.len()` or `buf.len()` times the size of `T` bytes, whichever is smaller,
/// to this slice's memory. The copy happens from smallest to largest address in
/// `T` sized chunks using volatile writes.
///
/// # Examples
///
/// ```
/// # use vm_memory::VolatileArrayRef;
/// #
/// let mut v = [0u8; 32];
/// let v_ref = unsafe { VolatileArrayRef::<u8>::new(v.as_mut_ptr(), v.len()) };
///
/// let buf = [5u8; 64];
/// v_ref.copy_from(&buf[..]);
/// for &val in &v[..] {
/// assert_eq!(5u8, val);
/// }
/// ```
pub fn copy_from(&self, buf: &[T]) {
// A fast path for u8/i8
if size_of::<T>() == 1 {
let destination = self.to_slice();
let total = buf.len().min(destination.len());
// absurd formatting brought to you by clippy
// SAFETY:
// - dst is valid for writes of at least `total`, since total <= destination.len()
// - src is valid for reads of at least `total` as total <= buf.len()
// - The regions are non-overlapping as `dst` points to guest memory and `buf` is
// a slice and thus has to live outside of guest memory (there can be more slices to
// guest memory without violating rust's aliasing rules)
// - size is always a multiple of alignment, so treating *const T as *const u8 is fine
unsafe { copy_to_volatile_slice(&destination, buf.as_ptr() as *const u8, total) };
} else {
let guard = self.ptr_guard_mut();
let start = guard.as_ptr();
let mut ptr = start as *mut Packed<T>;
for &v in buf.iter().take(self.len()) {
// SAFETY: write_volatile is safe because the pointers are range-checked when
// the slices are created, and they never escape the VolatileSlices.
// ptr::add is safe because get_array_ref() validated that
// size_of::<T>() * self.len() fits in an isize.
unsafe {
write_volatile(ptr, Packed::<T>(v));
ptr = ptr.add(1);
}
}
self.bitmap.mark_dirty(0, ptr as usize - start as usize);
}
}
}
impl<'a, B: BitmapSlice> From<VolatileSlice<'a, B>> for VolatileArrayRef<'a, u8, B> {
fn from(slice: VolatileSlice<'a, B>) -> Self {
// SAFETY: Safe because the result has the same lifetime and points to the same
// memory as the incoming VolatileSlice.
unsafe { VolatileArrayRef::with_bitmap(slice.addr, slice.len(), slice.bitmap, slice.mmap) }
}
}
// Return the largest value that `addr` is aligned to. Forcing this function to return 1 will
// cause test_non_atomic_access to fail.
fn alignment(addr: usize) -> usize {
// Rust is silly and does not let me write addr & -addr.
addr & (!addr + 1)
}
mod copy_slice_impl {
use super::*;
// SAFETY: Has the same safety requirements as `read_volatile` + `write_volatile`, namely:
// - `src_addr` and `dst_addr` must be valid for reads/writes.
// - `src_addr` and `dst_addr` must be properly aligned with respect to `align`.
// - `src_addr` must point to a properly initialized value, which is true here because
// we're only using integer primitives.
unsafe fn copy_single(align: usize, src_addr: *const u8, dst_addr: *mut u8) {
match align {
8 => write_volatile(dst_addr as *mut u64, read_volatile(src_addr as *const u64)),
4 => write_volatile(dst_addr as *mut u32, read_volatile(src_addr as *const u32)),
2 => write_volatile(dst_addr as *mut u16, read_volatile(src_addr as *const u16)),
1 => write_volatile(dst_addr, read_volatile(src_addr)),
_ => unreachable!(),
}
}
/// Copies `total` bytes from `src` to `dst` using a loop of volatile reads and writes
///
/// SAFETY: `src` and `dst` must be point to a contiguously allocated memory region of at least
/// length `total`. The regions must not overlap
unsafe fn copy_slice_volatile(mut dst: *mut u8, mut src: *const u8, total: usize) -> usize {
let mut left = total;
let align = min(alignment(src as usize), alignment(dst as usize));
let mut copy_aligned_slice = |min_align| {
if align < min_align {
return;
}
while left >= min_align {
// SAFETY: Safe because we check alignment beforehand, the memory areas are valid
// for reads/writes, and the source always contains a valid value.
unsafe { copy_single(min_align, src, dst) };
left -= min_align;
if left == 0 {
break;
}
// SAFETY: We only explain the invariants for `src`, the argument for `dst` is
// analogous.
// - `src` and `src + min_align` are within (or one byte past) the same allocated object
// This is given by the invariant on this function ensuring that [src, src + total)
// are part of the same allocated object, and the condition on the while loop
// ensures that we do not go outside this object
// - The computed offset in bytes cannot overflow isize, because `min_align` is at
// most 8 when the closure is called (see below)
// - The sum `src as usize + min_align` can only wrap around if src as usize + min_align - 1 == usize::MAX,
// however in this case, left == 0, and we'll have exited the loop above.
unsafe {
src = src.add(min_align);
dst = dst.add(min_align);
}
}
};
if size_of::<usize>() > 4 {
copy_aligned_slice(8);
}
copy_aligned_slice(4);
copy_aligned_slice(2);
copy_aligned_slice(1);
total
}
/// Copies `total` bytes from `src` to `dst`
///
/// SAFETY: `src` and `dst` must be point to a contiguously allocated memory region of at least
/// length `total`. The regions must not overlap
unsafe fn copy_slice(dst: *mut u8, src: *const u8, total: usize) -> usize {
if total <= size_of::<usize>() {
// SAFETY: Invariants of copy_slice_volatile are the same as invariants of copy_slice
unsafe {
copy_slice_volatile(dst, src, total);
};
} else {
// SAFETY:
// - Both src and dst are allocated for reads/writes of length `total` by function
// invariant
// - src and dst are properly aligned, as any alignment is valid for u8
// - The regions are not overlapping by function invariant
unsafe {
std::ptr::copy_nonoverlapping(src, dst, total);
}
}
total
}
/// Copies `total` bytes from `slice` to `dst`
///
/// SAFETY: `slice` and `dst` must be point to a contiguously allocated memory region of at
/// least length `total`. The regions must not overlap.
pub(super) unsafe fn copy_from_volatile_slice<B: BitmapSlice>(
dst: *mut u8,
slice: &VolatileSlice<'_, B>,
total: usize,
) -> usize {
let guard = slice.ptr_guard();
// SAFETY: guaranteed by function invariants.
copy_slice(dst, guard.as_ptr(), total)
}
/// Copies `total` bytes from 'src' to `slice`
///
/// SAFETY: `slice` and `src` must be point to a contiguously allocated memory region of at
/// least length `total`. The regions must not overlap.
pub(super) unsafe fn copy_to_volatile_slice<B: BitmapSlice>(
slice: &VolatileSlice<'_, B>,
src: *const u8,
total: usize,
) -> usize {
let guard = slice.ptr_guard_mut();
// SAFETY: guaranteed by function invariants.
let count = copy_slice(guard.as_ptr(), src, total);
slice.bitmap.mark_dirty(0, count);
count
}
}
#[cfg(test)]
mod tests {
#![allow(clippy::undocumented_unsafe_blocks)]
use super::*;
use std::alloc::Layout;
use std::fs::File;
use std::io::Cursor;
use std::mem::size_of_val;
use std::path::Path;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::{Arc, Barrier};
use std::thread::spawn;
use matches::assert_matches;
use vmm_sys_util::tempfile::TempFile;
use crate::bitmap::tests::{
check_range, range_is_clean, range_is_dirty, test_bytes, test_volatile_memory,
};
use crate::bitmap::{AtomicBitmap, RefSlice};
#[test]
fn test_display_error() {
assert_eq!(
format!("{}", Error::OutOfBounds { addr: 0x10 }),
"address 0x10 is out of bounds"
);
assert_eq!(
format!(
"{}",
Error::Overflow {
base: 0x0,
offset: 0x10
}
),
"address 0x0 offset by 0x10 would overflow"
);
assert_eq!(
format!(
"{}",
Error::TooBig {
nelements: 100_000,
size: 1_000_000_000
}
),
"100000 elements of size 1000000000 would overflow a usize"
);
assert_eq!(
format!(
"{}",
Error::Misaligned {
addr: 0x4,
alignment: 8
}
),
"address 0x4 is not aligned to 8"
);
assert_eq!(
format!(
"{}",
Error::PartialBuffer {
expected: 100,
completed: 90
}
),
"only used 90 bytes in 100 long buffer"
);
}
#[test]
fn misaligned_ref() {
let mut a = [0u8; 3];
let a_ref = VolatileSlice::from(&mut a[..]);
unsafe {
assert!(
a_ref.aligned_as_ref::<u16>(0).is_err() ^ a_ref.aligned_as_ref::<u16>(1).is_err()
);
assert!(
a_ref.aligned_as_mut::<u16>(0).is_err() ^ a_ref.aligned_as_mut::<u16>(1).is_err()
);
}
}
#[test]
fn atomic_store() {
let mut a = [0usize; 1];
{
let a_ref = unsafe {
VolatileSlice::new(&mut a[0] as *mut usize as *mut u8, size_of::<usize>())
};
let atomic = a_ref.get_atomic_ref::<AtomicUsize>(0).unwrap();
atomic.store(2usize, Ordering::Relaxed)
}
assert_eq!(a[0], 2);
}
#[test]
fn atomic_load() {
let mut a = [5usize; 1];
{
let a_ref = unsafe {
VolatileSlice::new(&mut a[0] as *mut usize as *mut u8,
size_of::<usize>())
};
let atomic = {
let atomic = a_ref.get_atomic_ref::<AtomicUsize>(0).unwrap();
assert_eq!(atomic.load(Ordering::Relaxed), 5usize);
atomic
};
// To make sure we can take the atomic out of the scope we made it in:
atomic.load(Ordering::Relaxed);
// but not too far:
// atomicu8
} //.load(std::sync::atomic::Ordering::Relaxed)
;
}
#[test]
fn misaligned_atomic() {
let mut a = [5usize, 5usize];
let a_ref =
unsafe { VolatileSlice::new(&mut a[0] as *mut usize as *mut u8, size_of::<usize>()) };
assert!(a_ref.get_atomic_ref::<AtomicUsize>(0).is_ok());
assert!(a_ref.get_atomic_ref::<AtomicUsize>(1).is_err());
}
#[test]
fn ref_store() {
let mut a = [0u8; 1];
{
let a_ref = VolatileSlice::from(&mut a[..]);
let v_ref = a_ref.get_ref(0).unwrap();
v_ref.store(2u8);
}
assert_eq!(a[0], 2);
}
#[test]
fn ref_load() {
let mut a = [5u8; 1];
{
let a_ref = VolatileSlice::from(&mut a[..]);
let c = {
let v_ref = a_ref.get_ref::<u8>(0).unwrap();
assert_eq!(v_ref.load(), 5u8);
v_ref
};
// To make sure we can take a v_ref out of the scope we made it in:
c.load();
// but not too far:
// c
} //.load()
;
}
#[test]
fn ref_to_slice() {
let mut a = [1u8; 5];
let a_ref = VolatileSlice::from(&mut a[..]);
let v_ref = a_ref.get_ref(1).unwrap();
v_ref.store(0x1234_5678u32);
let ref_slice = v_ref.to_slice();
assert_eq!(v_ref.addr as usize, ref_slice.addr as usize);
assert_eq!(v_ref.len(), ref_slice.len());
assert!(!ref_slice.is_empty());
}
#[test]
fn observe_mutate() {
struct RawMemory(*mut u8);
// SAFETY: we use property synchronization below
unsafe impl Send for RawMemory {}
unsafe impl Sync for RawMemory {}
let mem = Arc::new(RawMemory(unsafe {
std::alloc::alloc(Layout::from_size_align(1, 1).unwrap())
}));
let outside_slice = unsafe { VolatileSlice::new(Arc::clone(&mem).0, 1) };
let inside_arc = Arc::clone(&mem);
let v_ref = outside_slice.get_ref::<u8>(0).unwrap();
let barrier = Arc::new(Barrier::new(2));
let barrier1 = barrier.clone();
v_ref.store(99);
spawn(move || {
barrier1.wait();
let inside_slice = unsafe { VolatileSlice::new(inside_arc.0, 1) };
let clone_v_ref = inside_slice.get_ref::<u8>(0).unwrap();
clone_v_ref.store(0);
barrier1.wait();
});
assert_eq!(v_ref.load(), 99);
barrier.wait();
barrier.wait();
assert_eq!(v_ref.load(), 0);
unsafe { std::alloc::dealloc(mem.0, Layout::from_size_align(1, 1).unwrap()) }
}
#[test]
fn mem_is_empty() {
let mut backing = vec![0u8; 100];
let a = VolatileSlice::from(backing.as_mut_slice());
assert!(!a.is_empty());
let mut backing = vec![];
let a = VolatileSlice::from(backing.as_mut_slice());
assert!(a.is_empty());
}
#[test]
fn slice_len() {
let mut backing = vec![0u8; 100];
let mem = VolatileSlice::from(backing.as_mut_slice());
let slice = mem.get_slice(0, 27).unwrap();
assert_eq!(slice.len(), 27);
assert!(!slice.is_empty());
let slice = mem.get_slice(34, 27).unwrap();
assert_eq!(slice.len(), 27);
assert!(!slice.is_empty());
let slice = slice.get_slice(20, 5).unwrap();
assert_eq!(slice.len(), 5);
assert!(!slice.is_empty());
let slice = mem.get_slice(34, 0).unwrap();
assert!(slice.is_empty());
}
#[test]
fn slice_subslice() {
let mut backing = vec![0u8; 100];
let mem = VolatileSlice::from(backing.as_mut_slice());
let slice = mem.get_slice(0, 100).unwrap();
assert!(slice.write(&[1; 80], 10).is_ok());
assert!(slice.subslice(0, 0).is_ok());
assert!(slice.subslice(0, 101).is_err());
assert!(slice.subslice(99, 0).is_ok());
assert!(slice.subslice(99, 1).is_ok());
assert!(slice.subslice(99, 2).is_err());
assert!(slice.subslice(100, 0).is_ok());
assert!(slice.subslice(100, 1).is_err());
assert!(slice.subslice(101, 0).is_err());
assert!(slice.subslice(101, 1).is_err());
assert!(slice.subslice(std::usize::MAX, 2).is_err());
assert!(slice.subslice(2, std::usize::MAX).is_err());
let maybe_offset_slice = slice.subslice(10, 80);
assert!(maybe_offset_slice.is_ok());
let offset_slice = maybe_offset_slice.unwrap();
assert_eq!(offset_slice.len(), 80);
let mut buf = [0; 80];
assert!(offset_slice.read(&mut buf, 0).is_ok());
assert_eq!(&buf[0..80], &[1; 80][0..80]);
}
#[test]
fn slice_offset() {
let mut backing = vec![0u8; 100];
let mem = VolatileSlice::from(backing.as_mut_slice());
let slice = mem.get_slice(0, 100).unwrap();
assert!(slice.write(&[1; 80], 10).is_ok());
assert!(slice.offset(101).is_err());
let maybe_offset_slice = slice.offset(10);
assert!(maybe_offset_slice.is_ok());
let offset_slice = maybe_offset_slice.unwrap();
assert_eq!(offset_slice.len(), 90);
let mut buf = [0; 90];
assert!(offset_slice.read(&mut buf, 0).is_ok());
assert_eq!(&buf[0..80], &[1; 80][0..80]);
assert_eq!(&buf[80..90], &[0; 10][0..10]);
}
#[test]
fn slice_copy_to_u8() {
let mut a = [2u8, 4, 6, 8, 10];
let mut b = [0u8; 4];
let mut c = [0u8; 6];
let a_ref = VolatileSlice::from(&mut a[..]);
let v_ref = a_ref.get_slice(0, a_ref.len()).unwrap();
v_ref.copy_to(&mut b[..]);
v_ref.copy_to(&mut c[..]);
assert_eq!(b[0..4], a[0..4]);
assert_eq!(c[0..5], a[0..5]);
}
#[test]
fn slice_copy_to_u16() {
let mut a = [0x01u16, 0x2, 0x03, 0x4, 0x5];
let mut b = [0u16; 4];
let mut c = [0u16; 6];
let a_ref = &mut a[..];
let v_ref = unsafe { VolatileSlice::new(a_ref.as_mut_ptr() as *mut u8, 9) };
v_ref.copy_to(&mut b[..]);
v_ref.copy_to(&mut c[..]);
assert_eq!(b[0..4], a_ref[0..4]);
assert_eq!(c[0..4], a_ref[0..4]);
assert_eq!(c[4], 0);
}
#[test]
fn slice_copy_from_u8() {
let a = [2u8, 4, 6, 8, 10];
let mut b = [0u8; 4];
let mut c = [0u8; 6];
let b_ref = VolatileSlice::from(&mut b[..]);
let v_ref = b_ref.get_slice(0, b_ref.len()).unwrap();
v_ref.copy_from(&a[..]);
assert_eq!(b[0..4], a[0..4]);
let c_ref = VolatileSlice::from(&mut c[..]);
let v_ref = c_ref.get_slice(0, c_ref.len()).unwrap();
v_ref.copy_from(&a[..]);
assert_eq!(c[0..5], a[0..5]);
}
#[test]
fn slice_copy_from_u16() {
let a = [2u16, 4, 6, 8, 10];
let mut b = [0u16; 4];
let mut c = [0u16; 6];
let b_ref = &mut b[..];
let v_ref = unsafe { VolatileSlice::new(b_ref.as_mut_ptr() as *mut u8, 8) };
v_ref.copy_from(&a[..]);
assert_eq!(b_ref[0..4], a[0..4]);
let c_ref = &mut c[..];
let v_ref = unsafe { VolatileSlice::new(c_ref.as_mut_ptr() as *mut u8, 9) };
v_ref.copy_from(&a[..]);
assert_eq!(c_ref[0..4], a[0..4]);
assert_eq!(c_ref[4], 0);
}
#[test]
fn slice_copy_to_volatile_slice() {
let mut a = [2u8, 4, 6, 8, 10];
let a_ref = VolatileSlice::from(&mut a[..]);
let a_slice = a_ref.get_slice(0, a_ref.len()).unwrap();
let mut b = [0u8; 4];
let b_ref = VolatileSlice::from(&mut b[..]);
let b_slice = b_ref.get_slice(0, b_ref.len()).unwrap();
a_slice.copy_to_volatile_slice(b_slice);
assert_eq!(b, [2, 4, 6, 8]);
}
#[test]
fn slice_overflow_error() {
use std::usize::MAX;
let mut backing = vec![0u8];
let a = VolatileSlice::from(backing.as_mut_slice());
let res = a.get_slice(MAX, 1).unwrap_err();
assert_matches!(
res,
Error::Overflow {
base: MAX,
offset: 1,
}
);
}
#[test]
fn slice_oob_error() {
let mut backing = vec![0u8; 100];
let a = VolatileSlice::from(backing.as_mut_slice());
a.get_slice(50, 50).unwrap();
let res = a.get_slice(55, 50).unwrap_err();
assert_matches!(res, Error::OutOfBounds { addr: 105 });
}
#[test]
fn ref_overflow_error() {
use std::usize::MAX;
let mut backing = vec![0u8];
let a = VolatileSlice::from(backing.as_mut_slice());
let res = a.get_ref::<u8>(MAX).unwrap_err();
assert_matches!(
res,
Error::Overflow {
base: MAX,
offset: 1,
}
);
}
#[test]
fn ref_oob_error() {
let mut backing = vec![0u8; 100];
let a = VolatileSlice::from(backing.as_mut_slice());
a.get_ref::<u8>(99).unwrap();
let res = a.get_ref::<u16>(99).unwrap_err();
assert_matches!(res, Error::OutOfBounds { addr: 101 });
}
#[test]
fn ref_oob_too_large() {
let mut backing = vec![0u8; 3];
let a = VolatileSlice::from(backing.as_mut_slice());
let res = a.get_ref::<u32>(0).unwrap_err();
assert_matches!(res, Error::OutOfBounds { addr: 4 });
}
#[test]
fn slice_store() {
let mut backing = vec![0u8; 5];
let a = VolatileSlice::from(backing.as_mut_slice());
let s = a.as_volatile_slice();
let r = a.get_ref(2).unwrap();
r.store(9u16);
assert_eq!(s.read_obj::<u16>(2).unwrap(), 9);
}
#[test]
fn test_write_past_end() {
let mut backing = vec![0u8; 5];
let a = VolatileSlice::from(backing.as_mut_slice());
let s = a.as_volatile_slice();
let res = s.write(&[1, 2, 3, 4, 5, 6], 0);
assert!(res.is_ok());
assert_eq!(res.unwrap(), 5);
}
#[test]
fn slice_read_and_write() {
let mut backing = vec![0u8; 5];
let a = VolatileSlice::from(backing.as_mut_slice());
let s = a.as_volatile_slice();
let sample_buf = [1, 2, 3];
assert!(s.write(&sample_buf, 5).is_err());
assert!(s.write(&sample_buf, 2).is_ok());
let mut buf = [0u8; 3];
assert!(s.read(&mut buf, 5).is_err());
assert!(s.read_slice(&mut buf, 2).is_ok());
assert_eq!(buf, sample_buf);
// Writing an empty buffer at the end of the volatile slice works.
assert_eq!(s.write(&[], 100).unwrap(), 0);
let buf: &mut [u8] = &mut [];
assert_eq!(s.read(buf, 4).unwrap(), 0);
// Check that reading and writing an empty buffer does not yield an error.
let mut backing = Vec::new();
let empty_mem = VolatileSlice::from(backing.as_mut_slice());
let empty = empty_mem.as_volatile_slice();
assert_eq!(empty.write(&[], 1).unwrap(), 0);
assert_eq!(empty.read(buf, 1).unwrap(), 0);
}
#[test]
fn obj_read_and_write() {
let mut backing = vec![0u8; 5];
let a = VolatileSlice::from(backing.as_mut_slice());
let s = a.as_volatile_slice();
assert!(s.write_obj(55u16, 4).is_err());
assert!(s.write_obj(55u16, core::usize::MAX).is_err());
assert!(s.write_obj(55u16, 2).is_ok());
assert_eq!(s.read_obj::<u16>(2).unwrap(), 55u16);
assert!(s.read_obj::<u16>(4).is_err());
assert!(s.read_obj::<u16>(core::usize::MAX).is_err());
}
#[test]
fn mem_read_and_write() {
let mut backing = vec![0u8; 5];
let a = VolatileSlice::from(backing.as_mut_slice());
let s = a.as_volatile_slice();
assert!(s.write_obj(!0u32, 1).is_ok());
let mut file = if cfg!(unix) {
File::open(Path::new("/dev/zero")).unwrap()
} else {
File::open(Path::new("c:\\Windows\\system32\\ntoskrnl.exe")).unwrap()
};
assert!(s.read_exact_from(2, &mut file, size_of::<u32>()).is_err());
assert!(s
.read_exact_from(core::usize::MAX, &mut file, size_of::<u32>())
.is_err());
assert!(s.read_exact_from(1, &mut file, size_of::<u32>()).is_ok());
let mut f = TempFile::new().unwrap().into_file();
assert!(s.read_exact_from(1, &mut f, size_of::<u32>()).is_err());
format!("{:?}", s.read_exact_from(1, &mut f, size_of::<u32>()));
let value = s.read_obj::<u32>(1).unwrap();
if cfg!(unix) {
assert_eq!(value, 0);
} else {
assert_eq!(value, 0x0090_5a4d);
}
let mut sink = Vec::new();
assert!(s.write_all_to(1, &mut sink, size_of::<u32>()).is_ok());
assert!(s.write_all_to(2, &mut sink, size_of::<u32>()).is_err());
assert!(s
.write_all_to(core::usize::MAX, &mut sink, size_of::<u32>())
.is_err());
format!("{:?}", s.write_all_to(2, &mut sink, size_of::<u32>()));
if cfg!(unix) {
assert_eq!(sink, vec![0; size_of::<u32>()]);
} else {
assert_eq!(sink, vec![0x4d, 0x5a, 0x90, 0x00]);
};
}
#[test]
fn unaligned_read_and_write() {
let mut backing = vec![0u8; 7];
let a = VolatileSlice::from(backing.as_mut_slice());
let s = a.as_volatile_slice();
let sample_buf: [u8; 7] = [1, 2, 0xAA, 0xAA, 0xAA, 0xAA, 4];
assert!(s.write_slice(&sample_buf, 0).is_ok());
let r = a.get_ref::<u32>(2).unwrap();
assert_eq!(r.load(), 0xAAAA_AAAA);
r.store(0x5555_5555);
let sample_buf: [u8; 7] = [1, 2, 0x55, 0x55, 0x55, 0x55, 4];
let mut buf: [u8; 7] = Default::default();
assert!(s.read_slice(&mut buf, 0).is_ok());
assert_eq!(buf, sample_buf);
}
#[test]
fn test_read_from_exceeds_size() {
#[derive(Debug, Default, Copy, Clone)]
struct BytesToRead {
_val1: u128, // 16 bytes
_val2: u128, // 16 bytes
}
unsafe impl ByteValued for BytesToRead {}
let cursor_size = 20;
let mut image = Cursor::new(vec![1u8; cursor_size]);
// Trying to read more bytes than we have available in the cursor should
// make the read_from function return maximum cursor size (i.e. 20).
let mut bytes_to_read = BytesToRead::default();
let size_of_bytes = size_of_val(&bytes_to_read);
assert_eq!(
bytes_to_read
.as_bytes()
.read_from(0, &mut image, size_of_bytes)
.unwrap(),
cursor_size
);
}
#[test]
fn ref_array_from_slice() {
let mut a = [2, 4, 6, 8, 10];
let a_vec = a.to_vec();
let a_ref = VolatileSlice::from(&mut a[..]);
let a_slice = a_ref.get_slice(0, a_ref.len()).unwrap();
let a_array_ref: VolatileArrayRef<u8, ()> = a_slice.into();
for (i, entry) in a_vec.iter().enumerate() {
assert_eq!(&a_array_ref.load(i), entry);
}
}
#[test]
fn ref_array_store() {
let mut a = [0u8; 5];
{
let a_ref = VolatileSlice::from(&mut a[..]);
let v_ref = a_ref.get_array_ref(1, 4).unwrap();
v_ref.store(1, 2u8);
v_ref.store(2, 4u8);
v_ref.store(3, 6u8);
}
let expected = [2u8, 4u8, 6u8];
assert_eq!(a[2..=4], expected);
}
#[test]
fn ref_array_load() {
let mut a = [0, 0, 2, 3, 10];
{
let a_ref = VolatileSlice::from(&mut a[..]);
let c = {
let v_ref = a_ref.get_array_ref::<u8>(1, 4).unwrap();
assert_eq!(v_ref.load(1), 2u8);
assert_eq!(v_ref.load(2), 3u8);
assert_eq!(v_ref.load(3), 10u8);
v_ref
};
// To make sure we can take a v_ref out of the scope we made it in:
c.load(0);
// but not too far:
// c
} //.load()
;
}
#[test]
fn ref_array_overflow() {
let mut a = [0, 0, 2, 3, 10];
let a_ref = VolatileSlice::from(&mut a[..]);
let res = a_ref.get_array_ref::<u32>(4, usize::MAX).unwrap_err();
assert_matches!(
res,
Error::TooBig {
nelements: usize::MAX,
size: 4,
}
);
}
#[test]
fn alignment() {
let a = [0u8; 64];
let a = &a[a.as_ptr().align_offset(32)] as *const u8 as usize;
assert!(super::alignment(a) >= 32);
assert_eq!(super::alignment(a + 9), 1);
assert_eq!(super::alignment(a + 30), 2);
assert_eq!(super::alignment(a + 12), 4);
assert_eq!(super::alignment(a + 8), 8);
}
#[test]
fn test_atomic_accesses() {
let len = 0x1000;
let buf = unsafe { std::alloc::alloc_zeroed(Layout::from_size_align(len, 8).unwrap()) };
let a = unsafe { VolatileSlice::new(buf, len) };
crate::bytes::tests::check_atomic_accesses(a, 0, 0x1000);
unsafe {
std::alloc::dealloc(buf, Layout::from_size_align(len, 8).unwrap());
}
}
#[test]
fn split_at() {
let mut mem = [0u8; 32];
let mem_ref = VolatileSlice::from(&mut mem[..]);
let vslice = mem_ref.get_slice(0, 32).unwrap();
let (start, end) = vslice.split_at(8).unwrap();
assert_eq!(start.len(), 8);
assert_eq!(end.len(), 24);
let (start, end) = vslice.split_at(0).unwrap();
assert_eq!(start.len(), 0);
assert_eq!(end.len(), 32);
let (start, end) = vslice.split_at(31).unwrap();
assert_eq!(start.len(), 31);
assert_eq!(end.len(), 1);
let (start, end) = vslice.split_at(32).unwrap();
assert_eq!(start.len(), 32);
assert_eq!(end.len(), 0);
let err = vslice.split_at(33).unwrap_err();
assert_matches!(err, Error::OutOfBounds { addr: _ })
}
#[test]
fn test_volatile_slice_dirty_tracking() {
let val = 123u64;
let dirty_offset = 0x1000;
let dirty_len = size_of_val(&val);
let page_size = 0x1000;
let len = 0x10000;
let buf = unsafe { std::alloc::alloc_zeroed(Layout::from_size_align(len, 8).unwrap()) };
// Invoke the `Bytes` test helper function.
{
let bitmap = AtomicBitmap::new(len, page_size);
let slice = unsafe { VolatileSlice::with_bitmap(buf, len, bitmap.slice_at(0), None) };
test_bytes(
&slice,
|s: &VolatileSlice<RefSlice<AtomicBitmap>>,
start: usize,
len: usize,
clean: bool| { check_range(s.bitmap(), start, len, clean) },
|offset| offset,
0x1000,
);
}
// Invoke the `VolatileMemory` test helper function.
{
let bitmap = AtomicBitmap::new(len, page_size);
let slice = unsafe { VolatileSlice::with_bitmap(buf, len, bitmap.slice_at(0), None) };
test_volatile_memory(&slice);
}
let bitmap = AtomicBitmap::new(len, page_size);
let slice = unsafe { VolatileSlice::with_bitmap(buf, len, bitmap.slice_at(0), None) };
let bitmap2 = AtomicBitmap::new(len, page_size);
let slice2 = unsafe { VolatileSlice::with_bitmap(buf, len, bitmap2.slice_at(0), None) };
let bitmap3 = AtomicBitmap::new(len, page_size);
let slice3 = unsafe { VolatileSlice::with_bitmap(buf, len, bitmap3.slice_at(0), None) };
assert!(range_is_clean(slice.bitmap(), 0, slice.len()));
assert!(range_is_clean(slice2.bitmap(), 0, slice2.len()));
slice.write_obj(val, dirty_offset).unwrap();
assert!(range_is_dirty(slice.bitmap(), dirty_offset, dirty_len));
slice.copy_to_volatile_slice(slice2);
assert!(range_is_dirty(slice2.bitmap(), 0, slice2.len()));
{
let (s1, s2) = slice.split_at(dirty_offset).unwrap();
assert!(range_is_clean(s1.bitmap(), 0, s1.len()));
assert!(range_is_dirty(s2.bitmap(), 0, dirty_len));
}
{
let s = slice.subslice(dirty_offset, dirty_len).unwrap();
assert!(range_is_dirty(s.bitmap(), 0, s.len()));
}
{
let s = slice.offset(dirty_offset).unwrap();
assert!(range_is_dirty(s.bitmap(), 0, dirty_len));
}
// Test `copy_from` for size_of::<T> == 1.
{
let buf = vec![1u8; dirty_offset];
assert!(range_is_clean(slice.bitmap(), 0, dirty_offset));
slice.copy_from(&buf);
assert!(range_is_dirty(slice.bitmap(), 0, dirty_offset));
}
// Test `copy_from` for size_of::<T> > 1.
{
let val = 1u32;
let buf = vec![val; dirty_offset / size_of_val(&val)];
assert!(range_is_clean(slice3.bitmap(), 0, dirty_offset));
slice3.copy_from(&buf);
assert!(range_is_dirty(slice3.bitmap(), 0, dirty_offset));
}
unsafe {
std::alloc::dealloc(buf, Layout::from_size_align(len, 8).unwrap());
}
}
#[test]
fn test_volatile_ref_dirty_tracking() {
let val = 123u64;
let mut buf = vec![val];
let page_size = 0x1000;
let bitmap = AtomicBitmap::new(size_of_val(&val), page_size);
let vref = unsafe {
VolatileRef::with_bitmap(buf.as_mut_ptr() as *mut u8, bitmap.slice_at(0), None)
};
assert!(range_is_clean(vref.bitmap(), 0, vref.len()));
vref.store(val);
assert!(range_is_dirty(vref.bitmap(), 0, vref.len()));
}
fn test_volatile_array_ref_copy_from_tracking<T>(buf: &mut [T], index: usize, page_size: usize)
where
T: ByteValued + From<u8>,
{
let bitmap = AtomicBitmap::new(size_of_val(buf), page_size);
let arr = unsafe {
VolatileArrayRef::with_bitmap(
buf.as_mut_ptr() as *mut u8,
index + 1,
bitmap.slice_at(0),
None,
)
};
let val = T::from(123);
let copy_buf = vec![val; index + 1];
assert!(range_is_clean(arr.bitmap(), 0, arr.len() * size_of::<T>()));
arr.copy_from(copy_buf.as_slice());
assert!(range_is_dirty(arr.bitmap(), 0, size_of_val(buf)));
}
#[test]
fn test_volatile_array_ref_dirty_tracking() {
let val = 123u64;
let dirty_len = size_of_val(&val);
let index = 0x1000;
let dirty_offset = dirty_len * index;
let page_size = 0x1000;
let mut buf = vec![0u64; index + 1];
let mut byte_buf = vec![0u8; index + 1];
// Test `ref_at`.
{
let bitmap = AtomicBitmap::new(buf.len() * size_of_val(&val), page_size);
let arr = unsafe {
VolatileArrayRef::with_bitmap(
buf.as_mut_ptr() as *mut u8,
index + 1,
bitmap.slice_at(0),
None,
)
};
assert!(range_is_clean(arr.bitmap(), 0, arr.len() * dirty_len));
arr.ref_at(index).store(val);
assert!(range_is_dirty(arr.bitmap(), dirty_offset, dirty_len));
}
// Test `store`.
{
let bitmap = AtomicBitmap::new(buf.len() * size_of_val(&val), page_size);
let arr = unsafe {
VolatileArrayRef::with_bitmap(
buf.as_mut_ptr() as *mut u8,
index + 1,
bitmap.slice_at(0),
None,
)
};
let slice = arr.to_slice();
assert!(range_is_clean(slice.bitmap(), 0, slice.len()));
arr.store(index, val);
assert!(range_is_dirty(slice.bitmap(), dirty_offset, dirty_len));
}
// Test `copy_from` when size_of::<T>() == 1.
test_volatile_array_ref_copy_from_tracking(&mut byte_buf, index, page_size);
// Test `copy_from` when size_of::<T>() > 1.
test_volatile_array_ref_copy_from_tracking(&mut buf, index, page_size);
}
}