AbleOS/holey-bytes
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BMC is now interruptable

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This commit is contained in:
Erin 2023-07-26 02:04:26 +02:00
parent 6588837769
commit bdda987da9
5 changed files with 199 additions and 121 deletions
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2
hbvm/fuzz/fuzz_targets/vm.rs
View file

@ -9,7 +9,7 @@ use {
};
fuzz_target!(|data: &[u8]| {
if let Ok(mut vm) = Vm::<_, 0>::new_validated(data, TestTrapHandler, Default::default()) {
if let Ok(mut vm) = Vm::<_, 100>::new_validated(data, TestTrapHandler, Default::default()) {
let _ = vm.run();
}
});

55
hbvm/src/lib.rs
View file

@ -19,13 +19,12 @@ pub mod mem;
pub mod value;
use {
self::{mem::HandlePageFault, value::ValueVariant},
core::{cmp::Ordering, ops},
core::{cmp::Ordering, mem::size_of, ops},
hbbytecode::{
valider, OpParam, ParamBB, ParamBBB, ParamBBBB, ParamBBD, ParamBBDH, ParamBBW, ParamBD,
},
mem::Memory,
value::Value,
mem::{bmc::BlockCopier, HandlePageFault, Memory},
value::{Value, ValueVariant},
};
/// HoleyBytes Virtual Machine
@ -53,6 +52,9 @@ pub struct Vm<'a, PfHandler, const TIMER_QUOTIENT: usize> {
/// Program timer
timer: usize,
/// Saved block copier
copier: Option<BlockCopier>,
}
impl<'a, PfHandler: HandlePageFault, const TIMER_QUOTIENT: usize>
@ -71,6 +73,7 @@ impl<'a, PfHandler: HandlePageFault, const TIMER_QUOTIENT: usize>
program_len: program.len() - 12,
program,
timer: 0,
copier: None,
}
}
@ -255,13 +258,41 @@ impl<'a, PfHandler: HandlePageFault, const TIMER_QUOTIENT: usize>
}
BMC => {
// Block memory copy
let ParamBBD(src, dst, count) = self.decode();
self.memory.block_copy(
self.read_reg(src).cast::<u64>(),
self.read_reg(dst).cast::<u64>(),
count as _,
&mut self.pfhandler,
)?;
match if let Some(copier) = &mut self.copier {
// There is some copier, poll.
copier.poll(&mut self.memory, &mut self.pfhandler)
} else {
// There is none, make one!
let ParamBBD(src, dst, count) = self.decode();
// So we are still on BMC on next cycle
self.pc -= size_of::<ParamBBD>() + 1;
self.copier = Some(BlockCopier::new(
self.read_reg(src).cast(),
self.read_reg(dst).cast(),
count as _,
));
self.copier
.as_mut()
.unwrap_unchecked() // SAFETY: We just assigned there
.poll(&mut self.memory, &mut self.pfhandler)
} {
// We are done, shift program counter
core::task::Poll::Ready(Ok(())) => {
self.copier = None;
self.pc += size_of::<ParamBBD>() + 1;
}
// Error, shift program counter (for consistency)
// and yield error
core::task::Poll::Ready(Err(e)) => {
self.pc += size_of::<ParamBBD>() + 1;
return Err(e.into());
}
// Not done yet, proceed to next cycle
core::task::Poll::Pending => (),
}
}
BRC => {
// Block register copy
@ -353,7 +384,7 @@ impl<'a, PfHandler: HandlePageFault, const TIMER_QUOTIENT: usize>
#[inline]
unsafe fn decode<T: OpParam>(&mut self) -> T {
let data = self.program.as_ptr().add(self.pc + 1).cast::<T>().read();
self.pc += 1 + core::mem::size_of::<T>();
self.pc += 1 + size_of::<T>();
data
}

152
hbvm/src/mem/bmc.rs Normal file
View file

@ -0,0 +1,152 @@
use {
super::MemoryAccessReason,
crate::{
mem::{perm_check, HandlePageFault, Memory},
VmRunError,
},
core::{mem::MaybeUninit, task::Poll},
};
// Buffer size (defaults to 4 KiB, a smallest page size on most platforms)
const BUF_SIZE: usize = 4096;
// This should be equal to `BUF_SIZE`
#[repr(align(4096))]
struct AlignedBuf([MaybeUninit<u8>; BUF_SIZE]);
pub struct BlockCopier {
/// Source address
src: u64,
/// Destination address
dst: u64,
/// How many buffer sizes to copy?
n_buffers: usize,
/// …and what remainds after?
rem: usize,
}
impl BlockCopier {
pub fn new(src: u64, dst: u64, count: usize) -> Self {
Self {
src,
dst,
n_buffers: count / BUF_SIZE,
rem: count % BUF_SIZE,
}
}
/// Copy one block
///
/// # Safety
/// - Same as for [`Memory::load`] and [`Memory::store`]
pub unsafe fn poll(
&mut self,
memory: &mut Memory,
traph: &mut impl HandlePageFault,
) -> Poll<Result<(), BlkCopyError>> {
// Safety: Assuming uninit of array of MaybeUninit is sound
let mut buf = AlignedBuf(MaybeUninit::uninit().assume_init());
if self.n_buffers != 0 {
if let Err(e) = act(
memory,
self.src,
self.dst,
buf.0.as_mut_ptr().cast(),
BUF_SIZE,
traph,
) {
return Poll::Ready(Err(e));
}
self.src += BUF_SIZE as u64;
self.dst += BUF_SIZE as u64;
self.n_buffers -= 1;
return if self.n_buffers + self.rem == 0 {
// If there is nothing left, we are done
Poll::Ready(Ok(()))
} else {
// Otherwise let's advice to run it again
Poll::Pending
};
}
if self.rem != 0 {
if let Err(e) = act(
memory,
self.src,
self.dst,
buf.0.as_mut_ptr().cast(),
self.rem,
traph,
) {
return Poll::Ready(Err(e));
}
}
Poll::Ready(Ok(()))
}
}
#[inline]
unsafe fn act(
memory: &mut Memory,
src: u64,
dst: u64,
buf: *mut u8,
count: usize,
traph: &mut impl HandlePageFault,
) -> Result<(), BlkCopyError> {
// Load to buffer
memory
.memory_access(
MemoryAccessReason::Load,
src,
buf,
count,
perm_check::readable,
|src, dst, count| core::ptr::copy(src, dst, count),
traph,
)
.map_err(|addr| BlkCopyError {
access_reason: MemoryAccessReason::Load,
addr,
})?;
// Store from buffer
memory
.memory_access(
MemoryAccessReason::Store,
dst,
buf,
count,
perm_check::writable,
|dst, src, count| core::ptr::copy(src, dst, count),
traph,
)
.map_err(|addr| BlkCopyError {
access_reason: MemoryAccessReason::Store,
addr,
})?;
Ok(())
}
/// Error occured when copying a block of memory
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct BlkCopyError {
/// Kind of access
access_reason: MemoryAccessReason,
/// VM Address
addr: u64,
}
impl From<BlkCopyError> for VmRunError {
fn from(value: BlkCopyError) -> Self {
match value.access_reason {
MemoryAccessReason::Load => Self::LoadAccessEx(value.addr),
MemoryAccessReason::Store => Self::StoreAccessEx(value.addr),
}
}
}

107
hbvm/src/mem/mod.rs
View file

@ -1,6 +1,7 @@
//! Program memory implementation
pub mod paging;
pub mod bmc;
mod pfhandler;
@ -8,7 +9,6 @@ pub use pfhandler::HandlePageFault;
use {
super::VmRunError,
core::mem::MaybeUninit,
derive_more::Display,
paging::{PageTable, Permission},
};
@ -215,93 +215,6 @@ impl Memory {
.map_err(StoreError)
}
/// Copy a block of memory
///
/// # Safety
/// - Same as for [`Self::load`] and [`Self::store`]
/// - This function has been rewritten and is now pretty much boring
pub unsafe fn block_copy(
&mut self,
mut src: u64,
mut dst: u64,
count: usize,
traph: &mut impl HandlePageFault,
) -> Result<(), BlkCopyError> {
// Yea, i know it is possible to do this more efficiently, but I am too lazy.
impl Memory {
#[inline]
unsafe fn act(
&mut self,
src: u64,
dst: u64,
buf: *mut u8,
count: usize,
traph: &mut impl HandlePageFault,
) -> Result<(), BlkCopyError> {
// Load to buffer
self.memory_access(
MemoryAccessReason::Load,
src,
buf,
count,
perm_check::readable,
|src, dst, count| core::ptr::copy(src, dst, count),
traph,
)
.map_err(|addr| BlkCopyError {
access_reason: MemoryAccessReason::Load,
addr,
})?;
// Store from buffer
self.memory_access(
MemoryAccessReason::Store,
dst,
buf,
count,
perm_check::writable,
|dst, src, count| core::ptr::copy(src, dst, count),
traph,
)
.map_err(|addr| BlkCopyError {
access_reason: MemoryAccessReason::Store,
addr,
})?;
Ok(())
}
}
// Buffer size (defaults to 4 KiB, a smallest page size on most platforms)
const BUF_SIZE: usize = 4096;
// This should be equal to `BUF_SIZE`
#[repr(align(4096))]
struct AlignedBuf([MaybeUninit<u8>; BUF_SIZE]);
// Safety: Assuming uninit of array of MaybeUninit is sound
let mut buf = AlignedBuf(MaybeUninit::uninit().assume_init());
// Calculate how many times we need to copy buffer-sized blocks if any and the rest.
let n_buffers = count / BUF_SIZE;
let rem = count % BUF_SIZE;
// Copy buffer-sized blocks
for _ in 0..n_buffers {
self.act(src, dst, buf.0.as_mut_ptr().cast(), BUF_SIZE, traph)?;
src += BUF_SIZE as u64;
dst += BUF_SIZE as u64;
}
// Copy the rest (if any)
if rem != 0 {
self.act(src, dst, buf.0.as_mut_ptr().cast(), rem, traph)?;
}
Ok(())
}
// Everyone behold, the holy function, the god of HBVM memory accesses!
/// Split address to pages, check their permissions and feed pointers with offset
@ -534,24 +447,6 @@ pub enum MemoryAccessReason {
Store,
}
/// Error occured when copying a block of memory
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct BlkCopyError {
/// Kind of access
access_reason: MemoryAccessReason,
/// VM Address
addr: u64,
}
impl From<BlkCopyError> for VmRunError {
fn from(value: BlkCopyError) -> Self {
match value.access_reason {
MemoryAccessReason::Load => Self::LoadAccessEx(value.addr),
MemoryAccessReason::Store => Self::StoreAccessEx(value.addr),
}
}
}
impl From<LoadError> for VmRunError {
fn from(value: LoadError) -> Self {
Self::LoadAccessEx(value.0)

4
rustfmt.toml
View file

@ -1,4 +1,4 @@
hex_literal_case = "Upper"
imports_granularity = "One"
struct_field_align_threshold = 5
enum_discrim_align_threshold = 5
struct_field_align_threshold = 8
enum_discrim_align_threshold = 8