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new memory model. not quite complete

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This commit is contained in:
Pat Hickey
2020-01-27 18:20:47 -08:00
parent e6a4ae205c
commit ec456e9e50
8 changed files with 287 additions and 179 deletions
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6
crates/generate/src/funcs.rs
View File

@@ -74,7 +74,8 @@ pub fn define_func(names: &Names, func: &witx::InterfaceFunc) -> TokenStream {
let marshal_args = func
.params
.iter()
.map(|p| marshal_arg(names, p, error_handling.clone()));
//.map(|p| marshal_arg(names, p, error_handling.clone()));
.map(|_p| quote!(unimplemented!(); )); // FIXME
let trait_args = func
.params
.iter()
@@ -98,7 +99,8 @@ pub fn define_func(names: &Names, func: &witx::InterfaceFunc) -> TokenStream {
.results
.iter()
.skip(1)
.map(|result| marshal_result(names, result, error_handling.clone()));
//.map(|result| marshal_result(names, result, error_handling.clone()));
.map(|_result| (quote!(unimplemented!();), quote!(unimplemented!();))); // FIXME
let marshal_rets_pre = marshal_rets.clone().map(|(pre, _post)| pre);
let marshal_rets_post = marshal_rets.map(|(_pre, post)| post);

2
crates/generate/src/lib.rs
View File

@@ -34,7 +34,7 @@ pub fn from_witx(args: TokenStream) -> TokenStream {
mod #modname {
use super::WasiCtx;
use super::types::*;
#(#fs)*
// #(#fs)*
#modtrait
}

32
crates/generate/src/types.rs
View File

@@ -89,24 +89,30 @@ fn define_enum(names: &Names, name: &witx::Id, e: &witx::EnumDatatype) -> TokenS
fn size() -> u32 {
::std::mem::size_of::<#repr>() as u32
}
fn name() -> &'static str {
stringify!(#ident)
fn align() -> u32 {
::std::mem::align_of::<#repr>() as u32
}
fn name() -> String {
stringify!(#ident).to_owned()
}
fn validate<'a>(location: &::memory::GuestPtr<'a, #ident>) -> Result<(), ::memory::GuestError> {
use ::std::convert::TryFrom;
let raw: #repr = unsafe { (location.as_raw() as *const #repr).read() };
let _ = #ident::try_from(raw)?;
Ok(())
}
}
impl ::memory::GuestTypeCopy for #ident {
fn read_val<'a, P: ::memory::GuestPtrRead<'a, #ident>>(src: &P) -> Result<#ident, ::memory::GuestError> {
use ::std::convert::TryInto;
let val = unsafe { ::std::ptr::read_unaligned(src.ptr() as *const #repr) };
val.try_into()
}
fn write_val(val: #ident, dest: &::memory::GuestPtrMut<#ident>) {
let val: #repr = val.into();
unsafe {
::std::ptr::write_unaligned(dest.ptr_mut() as *mut #repr, val)
};
impl ::memory::GuestTypeCopy for #ident {}
impl ::memory::GuestTypeClone for #ident {
fn from_guest(location: &::memory::GuestPtr<#ident>) -> Result<#ident, ::memory::GuestError> {
use ::std::convert::TryFrom;
let raw: #repr = unsafe { (location.as_raw() as *const #repr).read() };
let val = #ident::try_from(raw)?;
Ok(val)
}
}
}
}

6
crates/memory/src/error.rs
View File

@@ -5,8 +5,10 @@ use thiserror::Error;
pub enum GuestError {
#[error("Invalid enum value {0}")]
InvalidEnumValue(&'static str),
#[error("Out of bounds: {0:?}")]
#[error("Pointer out of bounds: {0:?}")]
PtrOutOfBounds(Region),
#[error("Borrowed: {0:?}")]
#[error("Pointer not aligned to {1}: {0:?}")]
PtrNotAligned(Region, u32),
#[error("Pointer already borrowed: {0:?}")]
PtrBorrowed(Region),
}

62
crates/memory/src/guest_type.rs
View File

@@ -1,56 +1,39 @@
use crate::{GuestError, GuestPtrMut, GuestPtrRead};
use crate::{GuestError, GuestPtr};
pub trait GuestType: Sized {
// These are morally the same as Rust ::std::mem::size_of / align_of, but they return
// a u32 because the wasm memory space is 32 bits. They have a different names so they
// don't collide with the std::mem methods.
fn size() -> u32;
fn name() -> &'static str;
}
pub trait GuestTypeCopy: GuestType + Copy {
fn read_val<'a, P: GuestPtrRead<'a, Self>>(src: &P) -> Result<Self, GuestError>;
fn write_val(val: Self, dest: &GuestPtrMut<Self>);
fn align() -> u32;
fn name() -> String;
fn validate<'a>(location: &GuestPtr<'a, Self>) -> Result<(), GuestError>;
}
pub trait GuestTypeCopy: GuestType + Copy {}
pub trait GuestTypeClone: GuestType + Clone {
fn read_ref<'a, P: GuestPtrRead<'a, Self>>(src: &P, dest: &mut Self) -> Result<(), GuestError>;
fn write_ref(val: &Self, dest: &GuestPtrMut<Self>);
fn from_guest<'a>(location: &GuestPtr<'a, Self>) -> Result<Self, GuestError>;
}
pub trait GuestTypeRef<'a>: GuestType {
type Ref;
fn from_guest(location: &GuestPtr<'a, Self>) -> Result<Self::Ref, GuestError>;
}
impl<T> GuestTypeClone for T
where
T: GuestTypeCopy,
{
fn read_ref<'a, P: GuestPtrRead<'a, Self>>(src: &P, dest: &mut T) -> Result<(), GuestError> {
let val = GuestTypeCopy::read_val(src)?;
*dest = val;
Ok(())
}
fn write_ref(val: &T, dest: &GuestPtrMut<T>) {
GuestTypeCopy::write_val(*val, dest)
}
}
macro_rules! builtin_copy {
macro_rules! builtin_type {
( $( $t:ident ), * ) => {
$(
impl GuestType for $t {
fn size() -> u32 {
::std::mem::size_of::<$t>() as u32
}
fn name() -> &'static str {
::std::stringify!($t)
fn align() -> u32 {
::std::mem::align_of::<$t>() as u32
}
fn name() -> String {
::std::stringify!($t).to_owned()
}
impl GuestTypeCopy for $t {
fn read_val<'a, P: GuestPtrRead<'a, $t>>(src: &P) -> Result<$t, GuestError> {
Ok(unsafe {
::std::ptr::read_unaligned(src.ptr() as *const $t)
})
}
fn write_val(val: $t, dest: &GuestPtrMut<$t>) {
unsafe {
::std::ptr::write_unaligned(dest.ptr_mut() as *mut $t, val)
}
fn validate(_ptr: &GuestPtr<$t>) -> Result<(), GuestError> {
Ok(())
}
}
)*
@@ -58,7 +41,10 @@ macro_rules! builtin_copy {
}
// These definitions correspond to all the witx BuiltinType variants that are Copy:
builtin_copy!(u8, i8, u16, i16, u32, i32, u64, i64, f32, f64, usize, char);
builtin_type!(u8, i8, u16, i16, u32, i32, u64, i64, f32, f64, usize);
// FIXME implement GuestType for char. needs to validate that its a code point. what is the sizeof a char?
// FIXME implement GuestType for String. how does validate work for array types?
pub trait GuestErrorType {
type Context;

4
crates/memory/src/lib.rs
View File

@@ -5,6 +5,6 @@ mod memory;
mod region;
pub use error::GuestError;
pub use guest_type::{GuestErrorType, GuestType, GuestTypeClone, GuestTypeCopy};
pub use memory::{GuestMemory, GuestPtr, GuestPtrMut, GuestPtrRead};
pub use guest_type::{GuestErrorType, GuestType, GuestTypeClone, GuestTypeCopy, GuestTypeRef};
pub use memory::{GuestMemory, GuestPtr, GuestPtrMut, GuestRef, GuestRefMut};
pub use region::Region;

301
crates/memory/src/memory.rs
View File

@@ -3,7 +3,7 @@ use std::marker::PhantomData;
use std::rc::Rc;
use crate::borrow::{BorrowHandle, GuestBorrows};
use crate::{GuestError, GuestType, Region};
use crate::{GuestError, GuestType, GuestTypeCopy, GuestTypeRef, Region};
pub struct GuestMemory<'a> {
ptr: *mut u8,
@@ -14,6 +14,7 @@ pub struct GuestMemory<'a> {
impl<'a> GuestMemory<'a> {
pub fn new(ptr: *mut u8, len: u32) -> GuestMemory<'a> {
assert_eq!(ptr as usize % 4096, 0, "GuestMemory must be page-aligned");
GuestMemory {
ptr,
len,
@@ -36,145 +37,259 @@ impl<'a> GuestMemory<'a> {
if !self.contains(region) {
Err(GuestError::PtrOutOfBounds(region))?;
}
let mut borrows = self.borrows.borrow_mut();
if let Some(handle) = borrows.borrow_immut(region) {
if at % T::align() != 0 {
Err(GuestError::PtrNotAligned(region, T::align()))?;
}
Ok(GuestPtr {
mem: &self,
region,
handle,
type_: PhantomData,
})
} else {
Err(GuestError::PtrBorrowed(region))
}
}
pub fn ptr_mut<T: GuestType>(&'a self, at: u32) -> Result<GuestPtrMut<'a, T>, GuestError> {
let region = Region {
start: at,
len: T::size(),
};
if !self.contains(region) {
Err(GuestError::PtrOutOfBounds(region))?;
}
let mut borrows = self.borrows.borrow_mut();
if let Some(handle) = borrows.borrow_mut(region) {
let ptr = self.ptr(at)?;
Ok(GuestPtrMut {
mem: &self,
region,
handle,
type_: PhantomData,
mem: ptr.mem,
region: ptr.region,
type_: ptr.type_,
})
} else {
Err(GuestError::PtrBorrowed(region))
}
}
}
/// These methods should not be used by the end user - just by implementations of the
/// GuestValueClone and GuestValueCopy traits!
pub trait GuestPtrRead<'a, T> {
fn mem(&self) -> &'a GuestMemory<'a>;
fn region(&self) -> &Region;
fn ptr(&self) -> *const u8 {
(self.mem().ptr as usize + self.region().start as usize) as *const u8
}
}
#[derive(Clone)]
pub struct GuestPtr<'a, T> {
mem: &'a GuestMemory<'a>,
region: Region,
type_: PhantomData<T>,
}
impl<'a, T: GuestType> GuestPtr<'a, T> {
pub fn as_raw(&self) -> *const u8 {
(self.mem.ptr as usize + self.region.start as usize) as *const u8
}
pub fn as_ref(&self) -> Result<GuestRef<'a, T>, GuestError> {
T::validate(&self)?;
let handle = {
let mut borrows = self.mem.borrows.borrow_mut();
borrows
.borrow_immut(self.region)
.ok_or_else(|| GuestError::PtrBorrowed(self.region))?
};
Ok(GuestRef {
mem: self.mem,
region: self.region,
handle,
type_: self.type_,
})
}
}
impl<'a, T> GuestType for GuestPtr<'a, T>
where
T: GuestType,
{
fn size() -> u32 {
4
}
fn align() -> u32 {
4
}
fn name() -> String {
format!("GuestPtr<{}>", T::name())
}
fn validate<'b>(location: &GuestPtr<'b, GuestPtr<'b, T>>) -> Result<(), GuestError> {
// location is guaranteed to be in GuestMemory and aligned to 4
let raw_ptr: u32 = unsafe { *(location.as_raw() as *const u32) };
// GuestMemory can validate that the raw pointer contents are legal for T:
let _guest_ptr: GuestPtr<T> = location.mem.ptr(raw_ptr)?;
Ok(())
}
}
impl<'a, T> GuestTypeRef<'a> for GuestPtr<'a, T>
where
T: GuestType,
{
type Ref = GuestRef<'a, T>;
fn from_guest(location: &GuestPtr<'a, Self>) -> Result<Self::Ref, GuestError> {
// location is guaranteed to be in GuestMemory and aligned to 4
let raw_ptr: u32 = unsafe { *(location.as_raw() as *const u32) };
// GuestMemory can validate that the raw pointer contents are legal for T:
let guest_ptr: GuestPtr<'a, T> = location.mem.ptr(raw_ptr)?;
Ok(guest_ptr.as_ref()?)
}
}
#[derive(Clone)]
pub struct GuestPtrMut<'a, T> {
mem: &'a GuestMemory<'a>,
region: Region,
type_: PhantomData<T>,
}
impl<'a, T: GuestType> GuestPtrMut<'a, T> {
pub fn as_immut(&self) -> GuestPtr<'a, T> {
GuestPtr {
mem: self.mem,
region: self.region,
type_: self.type_,
}
}
pub fn as_raw(&self) -> *const u8 {
self.as_immut().as_raw()
}
pub fn as_ref(&self) -> Result<GuestRef<'a, T>, GuestError> {
self.as_immut().as_ref()
}
pub fn as_ref_mut(&self) -> Result<GuestRefMut<'a, T>, GuestError> {
T::validate(&self.as_immut())?;
let handle = {
let mut borrows = self.mem.borrows.borrow_mut();
borrows
.borrow_mut(self.region)
.ok_or_else(|| GuestError::PtrBorrowed(self.region))?
};
Ok(GuestRefMut {
mem: self.mem,
region: self.region,
handle,
type_: self.type_,
})
}
}
impl<'a, T> GuestType for GuestPtrMut<'a, T>
where
T: GuestType,
{
fn size() -> u32 {
4
}
fn align() -> u32 {
4
}
fn name() -> String {
format!("GuestPtrMut<{}>", T::name())
}
fn validate<'b>(location: &GuestPtr<'b, GuestPtrMut<'b, T>>) -> Result<(), GuestError> {
// location is guaranteed to be in GuestMemory and aligned to 4
let raw_ptr: u32 = unsafe { *(location.as_raw() as *const u32) };
// GuestMemory can validate that the raw pointer contents are legal for T:
let _guest_ptr: GuestPtr<T> = location.mem.ptr(raw_ptr)?;
Ok(())
}
}
impl<'a, T> GuestTypeRef<'a> for GuestPtrMut<'a, T>
where
T: GuestType,
{
type Ref = GuestRefMut<'a, T>;
fn from_guest(location: &GuestPtr<'a, Self>) -> Result<Self::Ref, GuestError> {
// location is guaranteed to be in GuestMemory and aligned to 4
let raw_ptr: u32 = unsafe { *(location.as_raw() as *const u32) };
// GuestMemory can validate that the raw pointer contents are legal for T:
let guest_ptr_mut: GuestPtrMut<'a, T> = location.mem.ptr_mut(raw_ptr)?;
Ok(guest_ptr_mut.as_ref_mut()?)
}
}
pub struct GuestRef<'a, T> {
mem: &'a GuestMemory<'a>,
region: Region,
handle: BorrowHandle,
type_: PhantomData<T>,
}
impl<'a, T> GuestPtrRead<'a, T> for GuestPtr<'a, T> {
fn mem(&self) -> &'a GuestMemory<'a> {
self.mem
impl<'a, T> ::std::ops::Deref for GuestRef<'a, T>
where
T: GuestTypeCopy,
{
type Target = T;
fn deref(&self) -> &T {
unsafe {
((self.mem.ptr as usize + self.region.start as usize) as *const T)
.as_ref()
.expect("GuestRef implies non-null")
}
fn region(&self) -> &Region {
&self.region
}
}
impl<'a, T> GuestType for GuestPtr<'a, T> {
fn size() -> u32 {
4
}
fn name() -> &'static str {
"GuestPtr<...>"
impl<'a, T> GuestRef<'a, T>
where
T: GuestTypeRef<'a>,
{
pub fn from_guest(&self) -> Result<T::Ref, GuestError> {
let ptr = GuestPtr {
mem: self.mem,
region: self.region,
type_: self.type_,
};
GuestTypeRef::from_guest(&ptr)
}
}
impl<'a, T: GuestType> GuestPtr<'a, T> {
pub fn read_ptr<P: GuestPtrRead<'a, Self>>(src: &P) -> Result<Self, GuestError> {
let raw_ptr = unsafe { ::std::ptr::read_unaligned(src.ptr() as *const u32) };
src.mem().ptr(raw_ptr)
}
pub fn write_ptr(ptr: &Self, dest: &GuestPtrMut<Self>) {
unsafe { ::std::ptr::write_unaligned(dest.ptr_mut() as *mut u32, ptr.region.start) }
}
}
impl<'a, T> Drop for GuestPtr<'a, T> {
impl<'a, T> Drop for GuestRef<'a, T> {
fn drop(&mut self) {
let mut borrows = self.mem.borrows.borrow_mut();
borrows.unborrow_immut(self.handle);
}
}
pub struct GuestPtrMut<'a, T> {
pub struct GuestRefMut<'a, T> {
mem: &'a GuestMemory<'a>,
region: Region,
handle: BorrowHandle,
type_: PhantomData<T>,
}
impl<'a, T> GuestPtrRead<'a, T> for GuestPtrMut<'a, T> {
fn mem(&self) -> &'a GuestMemory<'a> {
self.mem
impl<'a, T> ::std::ops::Deref for GuestRefMut<'a, T>
where
T: GuestTypeCopy,
{
type Target = T;
fn deref(&self) -> &T {
unsafe {
((self.mem.ptr as usize + self.region.start as usize) as *const T)
.as_ref()
.expect("GuestRef implies non-null")
}
fn region(&self) -> &Region {
&self.region
}
}
impl<'a, T> GuestPtrMut<'a, T> {
pub fn ptr_mut(&self) -> *mut u8 {
(self.mem.ptr as usize + self.region.start as usize) as *mut u8
impl<'a, T> ::std::ops::DerefMut for GuestRefMut<'a, T>
where
T: GuestTypeCopy,
{
fn deref_mut(&mut self) -> &mut T {
unsafe {
((self.mem.ptr as usize + self.region.start as usize) as *mut T)
.as_mut()
.expect("GuestRef implies non-null")
}
}
}
impl<'a, T> Drop for GuestPtrMut<'a, T> {
impl<'a, T> GuestRefMut<'a, T>
where
T: GuestTypeRef<'a>,
{
pub fn from_guest(&self) -> Result<T::Ref, GuestError> {
let ptr = GuestPtr {
mem: self.mem,
region: self.region,
type_: self.type_,
};
GuestTypeRef::from_guest(&ptr)
}
}
impl<'a, T> Drop for GuestRefMut<'a, T> {
fn drop(&mut self) {
let mut borrows = self.mem.borrows.borrow_mut();
borrows.unborrow_mut(self.handle);
}
}
impl<'a, T> GuestType for GuestPtrMut<'a, T> {
fn size() -> u32 {
4
}
fn name() -> &'static str {
"GuestPtrMut<...>"
}
}
impl<'a, T: GuestType> GuestPtrMut<'a, T> {
pub fn read_ptr<P: GuestPtrRead<'a, Self>>(src: &P) -> Result<Self, GuestError> {
let raw_ptr = unsafe { ::std::ptr::read_unaligned(src.ptr() as *const u32) };
src.mem().ptr_mut(raw_ptr)
}
pub fn write_ptr(ptr: &Self, dest: &GuestPtrMut<Self>) {
unsafe { ::std::ptr::write_unaligned(dest.ptr_mut() as *mut u32, ptr.region.start) }
}
pub fn as_immut(self) -> GuestPtr<'a, T> {
let mem = self.mem;
let start = self.region.start;
drop(self);
mem.ptr(start)
.expect("can borrow just-dropped mutable region as immut")
}
}

25
src/lib.rs
View File

@@ -18,43 +18,40 @@ pub mod test {
a_lamer_excuse_by_reference: ::memory::GuestPtr<types::Excuse>,
two_layers_of_excuses: ::memory::GuestPtrMut<::memory::GuestPtr<types::Excuse>>,
) -> Result<(), types::Errno> {
use memory::GuestTypeCopy;
// Read enum value from mutable:
let a_better_excuse =
types::Excuse::read_val(&a_better_excuse_by_reference).map_err(|e| {
let mut a_better_excuse_ref: ::memory::GuestRefMut<types::Excuse> =
a_better_excuse_by_reference.as_ref_mut().map_err(|e| {
eprintln!("a_better_excuse_by_reference error: {}", e);
types::Errno::InvalidArg
})?;
let a_better_excuse: types::Excuse = *a_better_excuse_ref;
// Read enum value from immutable ptr:
let a_lamer_excuse =
types::Excuse::read_val(&a_lamer_excuse_by_reference).map_err(|e| {
let a_lamer_excuse = *a_lamer_excuse_by_reference.as_ref().map_err(|e| {
eprintln!("a_lamer_excuse_by_reference error: {}", e);
types::Errno::InvalidArg
})?;
// Write enum to mutable ptr:
types::Excuse::write_val(a_lamer_excuse, &a_better_excuse_by_reference);
*a_better_excuse_ref = a_lamer_excuse;
// Read ptr value from mutable ptr:
let one_layer_down =
::memory::GuestPtr::read_ptr(&two_layers_of_excuses).map_err(|e| {
let mut one_layer_down: ::memory::GuestRefMut<::memory::GuestPtr<types::Excuse>> =
two_layers_of_excuses.as_ref_mut().map_err(|e| {
eprintln!("one_layer_down error: {}", e);
types::Errno::InvalidArg
})?;
// Read enum value from that ptr:
let two_layers_down = types::Excuse::read_val(&one_layer_down).map_err(|e| {
let two_layers_down: ::memory::GuestRef<types::Excuse> =
one_layer_down.from_guest().map_err(|e| {
eprintln!("two_layers_down error: {}", e);
types::Errno::InvalidArg
})?;
// Write ptr value to mutable ptr:
::memory::GuestPtr::write_ptr(
&a_better_excuse_by_reference.as_immut(),
&two_layers_of_excuses,
);
// FIXME this is still impossible...
// two_layers_of_excuses.write_guest(&a_better_excuse_by_reference)
println!(
"BAZ: excuse: {:?}, better excuse: {:?}, lamer excuse: {:?}, two layers down: {:?}",