forked from AbleOS/holey-bytes
Block memory copy
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6356b7dd24
commit
498e729c90
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@ -1,7 +1,9 @@
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mod paging;
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use core::mem::MaybeUninit;
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use self::paging::{PageTable, Permission, PtEntry};
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use super::trap::HandleTrap;
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use super::{trap::HandleTrap, VmRunError};
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use alloc::boxed::Box;
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use derive_more::Display;
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@ -105,37 +107,80 @@ impl Memory {
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}
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/// Copy a block of memory
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pub unsafe fn block_copy(&mut self, src: u64, dst: u64, count: u64) -> Result<(), ()> {
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/* let count = usize::try_from(count).expect("?conradluget a better CPU");
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///
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/// # Safety
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/// - Same as for [`Self::load`] and [`Self::store`]
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/// - Your faith in the gods of UB
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/// - Addr-san claims it's fine but who knows is she isn't lying :ferrisSus:
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pub unsafe fn block_copy(
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&mut self,
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src: u64,
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dst: u64,
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count: usize,
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traph: &mut impl HandleTrap,
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) -> Result<(), BlkCopyError> {
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// Yea, i know it is possible to do this more efficiently, but I am too lazy.
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let mut srcs = PageSplitter::new(src, count, self.root_pt);
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let mut dsts = PageSplitter::new(dst, count, self.root_pt);
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let mut c_src = srcs.next().ok_or(())?;
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let mut c_dst = dsts.next().ok_or(())?;
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const STACK_BUFFER_SIZE: usize = 512;
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loop {
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let min_size = c_src.size.min(c_dst.size);
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// Decide if to use stack-allocated buffer or to heap allocate
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// Deallocation is again decided on size at the end of the function
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let mut buf = MaybeUninit::<[u8; STACK_BUFFER_SIZE]>::uninit();
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let buf = if count <= STACK_BUFFER_SIZE {
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buf.as_mut_ptr().cast()
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} else {
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unsafe {
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core::ptr::copy(c_src.ptr, c_dst.ptr, min_size);
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}
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let layout = core::alloc::Layout::from_size_align_unchecked(count, 1);
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let ptr = alloc::alloc::alloc(layout);
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if ptr.is_null() {
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alloc::alloc::handle_alloc_error(layout);
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}
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match (
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match c_src.size.saturating_sub(min_size) {
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0 => srcs.next(),
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size => Some(PageSplitResult { size, ..c_src }),
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},
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match c_dst.size.saturating_sub(min_size) {
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0 => dsts.next(),
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size => Some(PageSplitResult { size, ..c_dst }),
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},
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) {
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(None, None) => return Ok(()),
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(Some(src), Some(dst)) => (c_src, c_dst) = (src, dst),
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_ => return Err(()),
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ptr
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}
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} */
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// TODO
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Err(())
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};
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// Perform memory block transfer
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let status = (|| {
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// Load to buffer
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self.memory_access(
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src,
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buf,
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count,
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|perm| {
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matches!(
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perm,
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Permission::Readonly | Permission::Write | Permission::Exec
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)
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},
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|src, dst, count| core::ptr::copy(src, dst, count),
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traph,
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)
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.map_err(|_| BlkCopyError::Load)?;
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// Store from buffer
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self.memory_access(
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dst,
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buf,
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count,
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|perm| perm == Permission::Write,
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|dst, src, count| core::ptr::copy(src, dst, count),
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traph,
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)
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.map_err(|_| BlkCopyError::Store)?;
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Ok::<_, BlkCopyError>(())
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})();
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// Deallocate if used heap-allocated array
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if count > STACK_BUFFER_SIZE {
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alloc::alloc::dealloc(
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buf,
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core::alloc::Layout::from_size_align_unchecked(count, 1),
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);
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}
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status
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}
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/// Split address to pages, check their permissions and feed pointers with offset
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@ -302,7 +347,7 @@ pub enum PageSize {
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/// 2 MiB page (on level 1)
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Size2M = 1024 * 1024 * 2,
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/// 1 GiB page (on level 2)
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Size1G = 1024 * 1024 * 1024,
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}
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@ -326,3 +371,31 @@ pub struct LoadError;
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/// Unhandled store access trap
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#[derive(Clone, Copy, Display, Debug, PartialEq, Eq)]
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pub struct StoreError;
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/// Unhandled block transfer trap
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#[derive(Clone, Copy, Display, Debug, PartialEq, Eq)]
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pub enum BlkCopyError {
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Load,
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Store,
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}
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impl From<LoadError> for VmRunError {
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fn from(_: LoadError) -> Self {
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Self::LoadAccessEx
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}
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}
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impl From<StoreError> for VmRunError {
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fn from(_: StoreError) -> Self {
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Self::StoreAccessEx
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}
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}
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impl From<BlkCopyError> for VmRunError {
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fn from(value: BlkCopyError) -> Self {
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match value {
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BlkCopyError::Load => Self::LoadAccessEx,
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BlkCopyError::Store => Self::StoreAccessEx,
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}
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}
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}
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@ -26,7 +26,6 @@ use {
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value::Value,
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};
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/// Extract a parameter from program
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macro_rules! param {
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($self:expr, $ty:ty) => {{
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@ -227,47 +226,30 @@ impl<'a, T: HandleTrap> Vm<'a, T> {
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_ => 0,
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};
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if self
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.memory
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.load(
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self.read_reg(base).as_u64() + off + n as u64,
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self.registers.as_mut_ptr().add(usize::from(dst) + n).cast(),
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usize::from(count).saturating_sub(n),
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&mut self.traph,
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)
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.is_err()
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{
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return Err(VmRunError::LoadAccessEx);
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}
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self.memory.load(
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self.read_reg(base).as_u64() + off + n as u64,
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self.registers.as_mut_ptr().add(usize::from(dst) + n).cast(),
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usize::from(count).saturating_sub(n),
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&mut self.traph,
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)?;
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}
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ST => {
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let ParamBBDH(dst, base, off, count) = param!(self, ParamBBDH);
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if self
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.memory
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.store(
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self.read_reg(base).as_u64() + off,
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self.registers.as_ptr().add(usize::from(dst)).cast(),
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count.into(),
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&mut self.traph,
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)
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.is_err()
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{
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return Err(VmRunError::LoadAccessEx);
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}
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self.memory.store(
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self.read_reg(base).as_u64() + off,
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self.registers.as_ptr().add(usize::from(dst)).cast(),
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count.into(),
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&mut self.traph,
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)?;
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}
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BMC => {
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let ParamBBD(src, dst, count) = param!(self, ParamBBD);
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if self
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.memory
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.block_copy(
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self.read_reg(src).as_u64(),
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self.read_reg(dst).as_u64(),
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count,
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)
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.is_err()
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{
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return Err(VmRunError::LoadAccessEx);
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}
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self.memory.block_copy(
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self.read_reg(src).as_u64(),
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self.read_reg(dst).as_u64(),
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count as _,
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&mut self.traph,
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)?;
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}
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BRC => {
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let ParamBBB(src, dst, count) = param!(self, ParamBBB);
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