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Mark unsound public methods as private utility functions (nervosnetwo…
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…rk#445)

* Marking cast_ptr_to_slice and cast_ptr_to_slice_mut unsafe

* Add # Safety section to cast_ptr_to_slice_mut's doc

* Mark unsound public methods as private utility functions
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@mohanson
mohanson authored Nov 28, 2024
1 parent c9351f4 commit abe964e
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Showing 2 changed files with 50 additions and 46 deletions.
18 changes: 0 additions & 18 deletions definitions/src/asm.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -164,21 +164,3 @@ impl AsmCoreMachine {
self.max_cycles = cycles;
}
}

impl AsmCoreMachine {
pub fn cast_ptr_to_slice(&self, ptr: u64, offset: usize, size: usize) -> &[u8] {
unsafe {
let ptr = ptr as *mut u8;
let ptr = ptr.add(offset);
std::slice::from_raw_parts(ptr, size)
}
}

pub fn cast_ptr_to_slice_mut(&self, ptr: u64, offset: usize, size: usize) -> &mut [u8] {
unsafe {
let ptr = ptr as *mut u8;
let ptr = ptr.add(offset);
std::slice::from_raw_parts_mut(ptr, size)
}
}
}
78 changes: 50 additions & 28 deletions src/machine/asm/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -81,8 +81,12 @@ impl CoreMachine for Box<AsmCoreMachine> {
#[no_mangle]
pub extern "C" fn inited_memory(frame_index: u64, machine: &mut AsmCoreMachine) {
let addr_from = (frame_index << MEMORY_FRAME_SHIFTS) as usize;
let slice =
machine.cast_ptr_to_slice_mut(machine.memory_ptr, addr_from, 1 << MEMORY_FRAME_SHIFTS);
let slice = cast_ptr_to_slice_mut(
machine,
machine.memory_ptr,
addr_from,
1 << MEMORY_FRAME_SHIFTS,
);
if machine.chaos_mode != 0 {
let mut gen = rand::rngs::StdRng::seed_from_u64(machine.chaos_seed.into());
gen.fill_bytes(slice);
Expand Down Expand Up @@ -236,9 +240,7 @@ impl<'a> FastMemory<'a> {
let page_indices = get_page_indices(addr, size);
for page in page_indices.0..=page_indices.1 {
let frame_index = page >> MEMORY_FRAME_PAGE_SHIFTS;
let slice = self
.0
.cast_ptr_to_slice_mut(self.0.frames_ptr, frame_index as usize, 1);
let slice = cast_ptr_to_slice_mut(self.0, self.0.frames_ptr, frame_index as usize, 1);
slice[0] = 1;
self.0.set_flag(page, FLAG_DIRTY)?;
}
Expand All @@ -254,9 +256,7 @@ impl<'a> Memory for FastMemory<'a> {
return Ok(());
}
self.prepare_memory(addr, value.len() as u64)?;
let slice = self
.0
.cast_ptr_to_slice_mut(self.0.memory_ptr, addr as usize, value.len());
let slice = cast_ptr_to_slice_mut(self.0, self.0.memory_ptr, addr as usize, value.len());
slice.copy_from_slice(value);
Ok(())
}
Expand All @@ -266,9 +266,7 @@ impl<'a> Memory for FastMemory<'a> {
return Ok(());
}
self.prepare_memory(addr, size)?;
let slice = self
.0
.cast_ptr_to_slice_mut(self.0.memory_ptr, addr as usize, size as usize);
let slice = cast_ptr_to_slice_mut(self.0, self.0.memory_ptr, addr as usize, size as usize);
memset(slice, value);
Ok(())
}
Expand Down Expand Up @@ -361,9 +359,9 @@ impl Memory for Box<AsmCoreMachine> {
type REG = u64;

fn reset_memory(&mut self) -> Result<(), Error> {
let slice = self.cast_ptr_to_slice_mut(self.flags_ptr, 0, self.flags_size as usize);
let slice = cast_ptr_to_slice_mut(self, self.flags_ptr, 0, self.flags_size as usize);
memset(slice, 0);
let slice = self.cast_ptr_to_slice_mut(self.frames_ptr, 0, self.frames_size as usize);
let slice = cast_ptr_to_slice_mut(self, self.frames_ptr, 0, self.frames_size as usize);
memset(slice, 0);
self.load_reservation_address = u64::MAX;
self.last_read_frame = u64::MAX;
Expand Down Expand Up @@ -428,7 +426,7 @@ impl Memory for Box<AsmCoreMachine> {

fn fetch_flag(&mut self, page: u64) -> Result<u8, Error> {
if page < self.memory_pages() as u64 {
let slice = self.cast_ptr_to_slice(self.flags_ptr, page as usize, 1);
let slice = cast_ptr_to_slice(self, self.flags_ptr, page as usize, 1);
Ok(slice[0])
} else {
Err(Error::MemOutOfBound(
Expand All @@ -440,7 +438,7 @@ impl Memory for Box<AsmCoreMachine> {

fn set_flag(&mut self, page: u64, flag: u8) -> Result<(), Error> {
if page < self.memory_pages() as u64 {
let slice = self.cast_ptr_to_slice_mut(self.flags_ptr, page as usize, 1);
let slice = cast_ptr_to_slice_mut(self, self.flags_ptr, page as usize, 1);
slice[0] |= flag;
// Clear last write page cache
self.last_write_page = u64::MAX;
Expand All @@ -455,7 +453,7 @@ impl Memory for Box<AsmCoreMachine> {

fn clear_flag(&mut self, page: u64, flag: u8) -> Result<(), Error> {
if page < self.memory_pages() as u64 {
let slice = self.cast_ptr_to_slice_mut(self.flags_ptr, page as usize, 1);
let slice = cast_ptr_to_slice_mut(self, self.flags_ptr, page as usize, 1);
slice[0] &= !flag;
// Clear last write page cache
self.last_write_page = u64::MAX;
Expand Down Expand Up @@ -483,7 +481,7 @@ impl Memory for Box<AsmCoreMachine> {
check_memory(self, page);
self.set_flag(page, FLAG_DIRTY)?;
}
let slice = self.cast_ptr_to_slice_mut(self.memory_ptr, addr as usize, value.len());
let slice = cast_ptr_to_slice_mut(self, self.memory_ptr, addr as usize, value.len());
slice.copy_from_slice(value);
Ok(())
}
Expand All @@ -499,7 +497,7 @@ impl Memory for Box<AsmCoreMachine> {
check_memory(self, page);
self.set_flag(page, FLAG_DIRTY)?;
}
let slice = self.cast_ptr_to_slice_mut(self.memory_ptr, addr as usize, size as usize);
let slice = cast_ptr_to_slice_mut(self, self.memory_ptr, addr as usize, size as usize);
memset(slice, value);
Ok(())
}
Expand All @@ -523,72 +521,72 @@ impl Memory for Box<AsmCoreMachine> {

fn execute_load16(&mut self, addr: u64) -> Result<u16, Error> {
check_memory_executable(self, addr, 2)?;
let slice = self.cast_ptr_to_slice(self.memory_ptr, addr as usize, 2);
let slice = cast_ptr_to_slice(self, self.memory_ptr, addr as usize, 2);
Ok(LittleEndian::read_u16(slice))
}

fn execute_load32(&mut self, addr: u64) -> Result<u32, Error> {
check_memory_executable(self, addr, 4)?;
let slice = self.cast_ptr_to_slice(self.memory_ptr, addr as usize, 4);
let slice = cast_ptr_to_slice(self, self.memory_ptr, addr as usize, 4);
Ok(LittleEndian::read_u32(slice))
}

fn load8(&mut self, addr: &u64) -> Result<u64, Error> {
let addr = *addr;
check_memory_inited(self, addr, 1)?;
let slice = self.cast_ptr_to_slice(self.memory_ptr, addr as usize, 1);
let slice = cast_ptr_to_slice(self, self.memory_ptr, addr as usize, 1);
Ok(u64::from(slice[0]))
}

fn load16(&mut self, addr: &u64) -> Result<u64, Error> {
let addr = *addr;
check_memory_inited(self, addr, 2)?;
let slice = self.cast_ptr_to_slice(self.memory_ptr, addr as usize, 2);
let slice = cast_ptr_to_slice(self, self.memory_ptr, addr as usize, 2);
Ok(u64::from(LittleEndian::read_u16(slice)))
}

fn load32(&mut self, addr: &u64) -> Result<u64, Error> {
let addr = *addr;
check_memory_inited(self, addr, 4)?;
let slice = self.cast_ptr_to_slice(self.memory_ptr, addr as usize, 4);
let slice = cast_ptr_to_slice(self, self.memory_ptr, addr as usize, 4);
Ok(u64::from(LittleEndian::read_u32(slice)))
}

fn load64(&mut self, addr: &u64) -> Result<u64, Error> {
let addr = *addr;
check_memory_inited(self, addr, 8)?;
let slice = self.cast_ptr_to_slice(self.memory_ptr, addr as usize, 8);
let slice = cast_ptr_to_slice(self, self.memory_ptr, addr as usize, 8);
Ok(LittleEndian::read_u64(slice))
}

fn store8(&mut self, addr: &u64, value: &u64) -> Result<(), Error> {
let addr = *addr;
check_memory_writable(self, addr, 1)?;
let slice = self.cast_ptr_to_slice_mut(self.memory_ptr, addr as usize, 1);
let slice = cast_ptr_to_slice_mut(self, self.memory_ptr, addr as usize, 1);
slice[0] = *value as u8;
Ok(())
}

fn store16(&mut self, addr: &u64, value: &u64) -> Result<(), Error> {
let addr = *addr;
check_memory_writable(self, addr, 2)?;
let slice = self.cast_ptr_to_slice_mut(self.memory_ptr, addr as usize, 2);
let slice = cast_ptr_to_slice_mut(self, self.memory_ptr, addr as usize, 2);
LittleEndian::write_u16(slice, *value as u16);
Ok(())
}

fn store32(&mut self, addr: &u64, value: &u64) -> Result<(), Error> {
let addr = *addr;
check_memory_writable(self, addr, 4)?;
let slice = self.cast_ptr_to_slice_mut(self.memory_ptr, addr as usize, 4);
let slice = cast_ptr_to_slice_mut(self, self.memory_ptr, addr as usize, 4);
LittleEndian::write_u32(slice, *value as u32);
Ok(())
}

fn store64(&mut self, addr: &u64, value: &u64) -> Result<(), Error> {
let addr = *addr;
check_memory_writable(self, addr, 8)?;
let slice = self.cast_ptr_to_slice_mut(self.memory_ptr, addr as usize, 8);
let slice = cast_ptr_to_slice_mut(self, self.memory_ptr, addr as usize, 8);
LittleEndian::write_u64(slice, *value as u64);
Ok(())
}
Expand Down Expand Up @@ -778,6 +776,30 @@ impl AsmMachine {
}
}

// Casts a raw pointer with an offset and size to a byte slice.
// We need machine here for the lifetime.
fn cast_ptr_to_slice(_machine: &AsmCoreMachine, ptr: u64, offset: usize, size: usize) -> &[u8] {
unsafe {
let ptr = ptr as *const u8;
let ptr = ptr.add(offset);
std::slice::from_raw_parts(ptr, size)
}
}

// Provides similar functionality to `cast_ptr_to_slice` but returns mut slice.
fn cast_ptr_to_slice_mut(
_machine: &AsmCoreMachine,
ptr: u64,
offset: usize,
size: usize,
) -> &mut [u8] {
unsafe {
let ptr = ptr as *mut u8;
let ptr = ptr.add(offset);
std::slice::from_raw_parts_mut(ptr, size)
}
}

#[cfg(test)]
mod tests {
use ckb_vm_definitions::asm::TRACE_ITEM_LENGTH;
Expand Down

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