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rpc: Port over size/alignment fix for structs (tuples) with tail padding 

This ports over the following commits from the main ARTIQ repo:
 - 8740ec3dd52d85084237797881ea137492bfe070
 - dbbe8e8ed4f852e623775b7bd3aec818cdd03376
 - b9f13d48aa7e2c0652210152b971b21c3c419347
This commit is contained in:
David Nadlinger 2022-12-29 12:27:50 +01:00
parent 800c12e794
commit df4988c774
1 changed files with 154 additions and 164 deletions
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318
src/runtime/src/rpc.rs
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@ -15,22 +15,85 @@ use crate::proto_async;
use self::tag::{Tag, TagIterator, split_tag};
#[inline]
fn alignment_offset(alignment: isize, ptr: isize) -> isize {
(alignment - ptr % alignment) % alignment
fn round_up(val: usize, power_of_two: usize) -> usize {
assert!(power_of_two.is_power_of_two());
let max_rem = power_of_two - 1;
(val + max_rem) & (!max_rem)
}
#[inline]
unsafe fn round_up_mut<T>(ptr: *mut T, power_of_two: usize) -> *mut T {
round_up(ptr as usize, power_of_two) as *mut T
}
#[inline]
unsafe fn round_up_const<T>(ptr: *const T, power_of_two: usize) -> *const T {
round_up(ptr as usize, power_of_two) as *const T
}
#[inline]
unsafe fn align_ptr<T>(ptr: *const ()) -> *const T {
let alignment = core::mem::align_of::<T>() as isize;
let fix = alignment_offset(alignment, ptr as isize);
((ptr as isize) + fix) as *const T
round_up_const(ptr, core::mem::align_of::<T>()) as *const T
}
#[inline]
unsafe fn align_ptr_mut<T>(ptr: *mut ()) -> *mut T {
let alignment = core::mem::align_of::<T>() as isize;
let fix = alignment_offset(alignment, ptr as isize);
((ptr as isize) + fix) as *mut T
round_up_mut(ptr, core::mem::align_of::<T>()) as *mut T
}
/// Reads (deserializes) `length` array or list elements of type `tag` from `stream`,
/// writing them into the buffer given by `storage`.
///
/// `alloc` is used for nested allocations (if elements themselves contain
/// lists/arrays), see [recv_value].
#[async_recursion(?Send)]
async unsafe fn recv_elements<F>(
stream: &TcpStream,
elt_tag: Tag<'async_recursion>,
length: usize,
storage: *mut (),
alloc: &(impl Fn(usize) -> F + 'async_recursion)
) -> Result<(), smoltcp::Error>
where
F: Future<Output=*mut ()>,
{
// List of simple types are special-cased in the protocol for performance.
match elt_tag {
Tag::Bool => {
let dest = core::slice::from_raw_parts_mut(storage as *mut u8, length);
proto_async::read_chunk(stream, dest).await?;
},
Tag::Int32 => {
let ptr = storage as *mut u32;
let dest = core::slice::from_raw_parts_mut(ptr as *mut u8, length * 4);
proto_async::read_chunk(stream, dest).await?;
drop(dest);
let dest = core::slice::from_raw_parts_mut(ptr, length);
NativeEndian::from_slice_u32(dest);
},
Tag::Int64 | Tag::Float64 => {
let ptr = storage as *mut u64;
let dest = core::slice::from_raw_parts_mut(ptr as *mut u8, length * 8);
proto_async::read_chunk(stream, dest).await?;
drop(dest);
let dest = core::slice::from_raw_parts_mut(ptr, length);
NativeEndian::from_slice_u64(dest);
},
_ => {
let mut data = storage;
for _ in 0..length {
recv_value(stream, elt_tag, &mut data, alloc).await?
}
}
}
Ok(())
}
/// Reads (deserializes) a value of type `tag` from `stream`, writing the results to
/// the kernel-side buffer `data` (the passed pointer to which is incremented to point
/// past the just-received data). For nested allocations (lists/arrays), `alloc` is
/// invoked any number of times with the size of the required allocation as a parameter
/// (which is assumed to be correctly aligned for all payload types).
#[async_recursion(?Send)]
async unsafe fn recv_value<F>(stream: &TcpStream, tag: Tag<'async_recursion>, data: &mut *mut (),
alloc: &(impl Fn(usize) -> F + 'async_recursion))
@ -71,120 +134,63 @@ async unsafe fn recv_value<F>(stream: &TcpStream, tag: Tag<'async_recursion>, da
})
}
Tag::Tuple(it, arity) => {
*data = (*data).offset(alignment_offset(tag.alignment() as isize, *data as isize));
let alignment = tag.alignment();
*data = round_up_mut(*data, alignment);
let mut it = it.clone();
for _ in 0..arity {
let tag = it.next().expect("truncated tag");
recv_value(stream, tag, data, alloc).await?;
recv_value(stream, tag, data, alloc).await?
}
// Take into account any tail padding (if element(s) with largest alignment
// are not at the end).
*data = round_up_mut(*data, alignment);
Ok(())
}
Tag::List(it) => {
#[repr(C)]
struct List { elements: *mut (), length: u32 }
consume_value!(*mut List, |ptr| {
let length = proto_async::read_i32(stream).await? as usize;
struct List { elements: *mut (), length: usize }
consume_value!(*mut List, |ptr_to_list| {
let tag = it.clone().next().expect("truncated tag");
let data_size = tag.size() * length as usize +
match tag {
Tag::Int64 | Tag::Float64 => 4,
_ => 0
};
let data = alloc(data_size + 8).await as *mut u8;
*ptr = data as *mut List;
let ptr = data as *mut List;
let data = data.offset(8);
let length = proto_async::read_i32(stream).await? as usize;
let alignment = tag.alignment();
let mut data = data.offset(alignment_offset(alignment as isize, data as isize)) as *mut ();
(*ptr).length = length as u32;
(*ptr).elements = data;
match tag {
Tag::Bool => {
let ptr = data as *mut u8;
let dest = core::slice::from_raw_parts_mut(ptr, length);
proto_async::read_chunk(stream, dest).await?;
},
Tag::Int32 => {
let ptr = data as *mut u32;
// reading as raw bytes and do endianness conversion later
let dest = core::slice::from_raw_parts_mut(ptr as *mut u8, length * 4);
proto_async::read_chunk(stream, dest).await?;
drop(dest);
let dest = core::slice::from_raw_parts_mut(ptr, length);
NativeEndian::from_slice_u32(dest);
},
Tag::Int64 | Tag::Float64 => {
let ptr = data as *mut u64;
let dest = core::slice::from_raw_parts_mut(ptr as *mut u8, length * 8);
proto_async::read_chunk(stream, dest).await?;
drop(dest);
let dest = core::slice::from_raw_parts_mut(ptr, length);
NativeEndian::from_slice_u64(dest);
},
_ => {
for _ in 0..(*ptr).length as usize {
recv_value(stream, tag, &mut data, alloc).await?
}
}
}
Ok(())
// To avoid multiple kernel CPU roundtrips, use a single allocation for
// both the pointer/length List (slice) and the backing storage for the
// elements. We can assume that alloc() is aligned suitably, so just
// need to take into account any extra padding required.
// (Note: At the time of writing, there will never actually be any types
// with alignment larger than 8 bytes, so storage_offset == 0 always.)
let list_size = 4 + 4;
let storage_offset = round_up(list_size, tag.alignment());
let storage_size = tag.size() * length;
let allocation = alloc(storage_offset + storage_size).await as *mut u8;
*ptr_to_list = allocation as *mut List;
let storage = allocation.offset(storage_offset as isize) as *mut ();
(**ptr_to_list).length = length;
(**ptr_to_list).elements = storage;
recv_elements(stream, tag, length, storage, alloc).await
})
}
Tag::Array(it, num_dims) => {
consume_value!(*mut (), |buffer| {
let mut total_len: u32 = 1;
// Deserialize length along each dimension and compute total number of
// elements.
let mut total_len: usize = 1;
for _ in 0..num_dims {
let len = proto_async::read_i32(stream).await? as u32;
let len = proto_async::read_i32(stream).await? as usize;
total_len *= len;
consume_value!(u32, |ptr| *ptr = len )
consume_value!(usize, |ptr| *ptr = len )
}
// Allocate backing storage for elements; deserialize them.
let elt_tag = it.clone().next().expect("truncated tag");
let data_size = elt_tag.size() * total_len as usize +
match elt_tag {
Tag::Int64 | Tag::Float64 => 4,
_ => 0
};
let mut data = alloc(data_size).await;
let alignment = tag.alignment();
data = data.offset(alignment_offset(alignment as isize, data as isize));
*buffer = data;
let length = total_len as usize;
match elt_tag {
Tag::Bool => {
let ptr = data as *mut u8;
let dest = core::slice::from_raw_parts_mut(ptr, length);
proto_async::read_chunk(stream, dest).await?;
},
Tag::Int32 => {
let ptr = data as *mut u32;
let dest = core::slice::from_raw_parts_mut(ptr as *mut u8, length * 4);
proto_async::read_chunk(stream, dest).await?;
drop(dest);
let dest = core::slice::from_raw_parts_mut(ptr, length);
NativeEndian::from_slice_u32(dest);
},
Tag::Int64 | Tag::Float64 => {
let ptr = data as *mut u64;
let dest = core::slice::from_raw_parts_mut(ptr as *mut u8, length * 8);
proto_async::read_chunk(stream, dest).await?;
drop(dest);
let dest = core::slice::from_raw_parts_mut(ptr, length);
NativeEndian::from_slice_u64(dest);
},
_ => {
for _ in 0..length {
recv_value(stream, elt_tag, &mut data, alloc).await?
}
}
}
Ok(())
*buffer = alloc(elt_tag.size() * total_len).await;
recv_elements(stream, elt_tag, total_len, *buffer, alloc).await
})
}
Tag::Range(it) => {
*data = (*data).offset(alignment_offset(tag.alignment() as isize, *data as isize));
*data = round_up_mut(*data, tag.alignment());
let tag = it.clone().next().expect("truncated tag");
recv_value(stream, tag, data, alloc).await?;
recv_value(stream, tag, data, alloc).await?;
@ -211,6 +217,36 @@ pub async fn recv_return<F>(stream: &TcpStream, tag_bytes: &[u8], data: *mut (),
Ok(())
}
unsafe fn send_elements<W>(writer: &mut W, elt_tag: Tag, length: usize, data: *const ())
-> Result<(), Error>
where W: Write + ?Sized
{
writer.write_u8(elt_tag.as_u8())?;
match elt_tag {
// we cannot use NativeEndian::from_slice_i32 as the data is not mutable,
// and that is not needed as the data is already in native endian
Tag::Bool => {
let slice = core::slice::from_raw_parts(data as *const u8, length);
writer.write_all(slice)?;
},
Tag::Int32 => {
let slice = core::slice::from_raw_parts(data as *const u8, length * 4);
writer.write_all(slice)?;
},
Tag::Int64 | Tag::Float64 => {
let slice = core::slice::from_raw_parts(data as *const u8, length * 8);
writer.write_all(slice)?;
},
_ => {
let mut data = data;
for _ in 0..length {
send_value(writer, elt_tag, &mut data)?;
}
}
}
Ok(())
}
unsafe fn send_value<W>(writer: &mut W, tag: Tag, data: &mut *const ())
-> Result<(), Error>
where W: Write + ?Sized
@ -244,46 +280,23 @@ unsafe fn send_value<W>(writer: &mut W, tag: Tag, data: &mut *const ())
Tag::Tuple(it, arity) => {
let mut it = it.clone();
writer.write_u8(arity)?;
let mut max_alignment = 0;
for _ in 0..arity {
let tag = it.next().expect("truncated tag");
max_alignment = core::cmp::max(max_alignment, tag.alignment());
send_value(writer, tag, data)?
}
*data = round_up_const(*data, max_alignment);
Ok(())
}
Tag::List(it) => {
#[repr(C)]
struct List { elements: *const (), length: u32 }
consume_value!(&List, |ptr| {
let length = (**ptr).length as isize;
let length = (**ptr).length as usize;
writer.write_u32((*ptr).length)?;
let tag = it.clone().next().expect("truncated tag");
let mut data = (**ptr).elements;
writer.write_u8(tag.as_u8())?;
match tag {
Tag::Bool => {
// we can pretend this is u8...
let ptr1 = align_ptr::<u8>(data);
let slice = core::slice::from_raw_parts(ptr1, length as usize);
writer.write_all(slice)?;
},
Tag::Int32 => {
let ptr1 = align_ptr::<i32>(data);
let slice = core::slice::from_raw_parts(ptr1 as *const u8, length as usize * 4);
writer.write_all(slice)?;
},
Tag::Int64 | Tag::Float64 => {
let ptr1 = align_ptr::<i64>(data);
let slice = core::slice::from_raw_parts(ptr1 as *const u8, length as usize * 8);
writer.write_all(slice)?;
},
// non-primitive types, not sure if this would happen but we can handle it...
_ => {
for _ in 0..length {
send_value(writer, tag, &mut data)?;
}
}
};
Ok(())
send_elements(writer, tag, length, (**ptr).elements)
})
}
Tag::Array(it, num_dims) => {
@ -298,33 +311,8 @@ unsafe fn send_value<W>(writer: &mut W, tag: Tag, data: &mut *const ())
total_len *= *len;
})
}
let mut data = *buffer;
let length = total_len as isize;
writer.write_u8(elt_tag.as_u8())?;
match elt_tag {
Tag::Bool => {
let ptr1 = align_ptr::<u8>(data);
let slice = core::slice::from_raw_parts(ptr1, length as usize);
writer.write_all(slice)?;
},
Tag::Int32 => {
let ptr1 = align_ptr::<i32>(data);
let slice = core::slice::from_raw_parts(ptr1 as *const u8, length as usize * 4);
writer.write_all(slice)?;
},
Tag::Int64 | Tag::Float64 => {
let ptr1 = align_ptr::<i64>(data);
let slice = core::slice::from_raw_parts(ptr1 as *const u8, length as usize * 8);
writer.write_all(slice)?;
},
// non-primitive types, not sure if this would happen but we can handle it...
_ => {
for _ in 0..length {
send_value(writer, elt_tag, &mut data)?;
}
}
};
Ok(())
let length = total_len as usize;
send_elements(writer, elt_tag, length, *buffer)
})
}
Tag::Range(it) => {
@ -448,18 +436,15 @@ mod tag {
let it = it.clone();
it.take(3).map(|t| t.alignment()).max().unwrap()
}
// CSlice basically
Tag::Bytes | Tag::String | Tag::ByteArray =>
// the ptr/length(s) pair is basically CSlice
Tag::Bytes | Tag::String | Tag::ByteArray | Tag::List(_) | Tag::Array(_, _) =>
core::mem::align_of::<CSlice<()>>(),
// array buffer is allocated, so no need for alignment first
Tag::List(_) | Tag::Array(_, _) => 1,
// will not be sent from the host
_ => unreachable!("unexpected tag from host")
Tag::Keyword(_) => unreachable!("Tag::Keyword should not appear in composite types"),
Tag::Object => core::mem::align_of::<u32>(),
}
}
pub fn size(self) -> usize {
use super::alignment_offset;
match self {
Tag::None => 0,
Tag::Bool => 1,
@ -471,13 +456,18 @@ mod tag {
Tag::ByteArray => 8,
Tag::Tuple(it, arity) => {
let mut size = 0;
let mut max_alignment = 0;
let mut it = it.clone();
for _ in 0..arity {
let tag = it.next().expect("truncated tag");
let alignment = tag.alignment();
max_alignment = core::cmp::max(max_alignment, alignment);
size = super::round_up(size, alignment);
size += tag.size();
// includes padding
size += alignment_offset(tag.alignment() as isize, size as isize) as usize;
}
// Take into account any tail padding (if element(s) with largest
// alignment are not at the end).
size = super::round_up(size, max_alignment);
size
}
Tag::List(_) => 4,