mirror of
https://github.com/fluencelabs/wasmer
synced 2025-06-24 22:21:32 +00:00
Improved instance
This commit is contained in:
Syrus Akbary
@ -1,158 +1,113 @@
|
||||
use errno;
|
||||
use libc;
|
||||
use region;
|
||||
use std::mem;
|
||||
use std::ptr;
|
||||
use memmap;
|
||||
use std::fmt;
|
||||
|
||||
/// Round `size` up to the nearest multiple of `page_size`.
|
||||
fn round_up_to_page_size(size: usize, page_size: usize) -> usize {
|
||||
(size + (page_size - 1)) & !(page_size - 1)
|
||||
const PAGE_SIZE: u32 = 65536;
|
||||
const MAX_PAGES: u32 = 65536;
|
||||
|
||||
/// A linear memory instance.
|
||||
///
|
||||
/// This linear memory has a stable base address and at the same time allows
|
||||
/// for dynamical growing.
|
||||
pub struct LinearMemory {
|
||||
mmap: memmap::MmapMut,
|
||||
current: u32,
|
||||
maximum: Option<u32>,
|
||||
}
|
||||
|
||||
/// A simple struct consisting of a pointer and length.
|
||||
struct PtrLen {
|
||||
ptr: *mut u8,
|
||||
len: usize,
|
||||
}
|
||||
impl LinearMemory {
|
||||
/// Create a new linear memory instance with specified initial and maximum number of pages.
|
||||
///
|
||||
/// `maximum` cannot be set to more than `65536` pages.
|
||||
pub fn new(initial: u32, maximum: Option<u32>) -> Self {
|
||||
assert!(initial <= MAX_PAGES);
|
||||
assert!(maximum.is_none() || maximum.unwrap() <= MAX_PAGES);
|
||||
|
||||
impl PtrLen {
|
||||
/// Create a new empty `PtrLen`.
|
||||
fn new() -> Self {
|
||||
Self {
|
||||
ptr: ptr::null_mut(),
|
||||
len: 0,
|
||||
}
|
||||
}
|
||||
|
||||
/// Create a new `PtrLen` pointing to at least `size` bytes of memory,
|
||||
/// suitably sized and aligned for memory protection.
|
||||
#[cfg(not(target_os = "windows"))]
|
||||
fn with_size(size: usize) -> Result<Self, String> {
|
||||
let page_size = region::page::size();
|
||||
let alloc_size = round_up_to_page_size(size, page_size);
|
||||
unsafe {
|
||||
let mut ptr: *mut libc::c_void = mem::uninitialized();
|
||||
let err = libc::posix_memalign(&mut ptr, page_size, alloc_size);
|
||||
if err == 0 {
|
||||
Ok(Self {
|
||||
ptr: ptr as *mut u8,
|
||||
len: alloc_size,
|
||||
})
|
||||
} else {
|
||||
Err(errno::Errno(err).to_string())
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
#[cfg(target_os = "windows")]
|
||||
fn with_size(size: usize) -> Result<Self, String> {
|
||||
use winapi::um::memoryapi::VirtualAlloc;
|
||||
use winapi::um::winnt::{MEM_COMMIT, MEM_RESERVE, PAGE_READWRITE};
|
||||
|
||||
let page_size = region::page::size();
|
||||
|
||||
// VirtualAlloc always rounds up to the next multiple of the page size
|
||||
let ptr = unsafe {
|
||||
VirtualAlloc(
|
||||
ptr::null_mut(),
|
||||
size,
|
||||
MEM_COMMIT | MEM_RESERVE,
|
||||
PAGE_READWRITE,
|
||||
)
|
||||
let len = PAGE_SIZE * match maximum {
|
||||
Some(val) => val,
|
||||
None => initial,
|
||||
};
|
||||
if !ptr.is_null() {
|
||||
Ok(Self {
|
||||
ptr: ptr as *mut u8,
|
||||
len: round_up_to_page_size(size, page_size),
|
||||
})
|
||||
} else {
|
||||
Err(errno::errno().to_string())
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// JIT memory manager. This manages pages of suitably aligned and
|
||||
/// accessible memory.
|
||||
pub struct Memory {
|
||||
allocations: Vec<PtrLen>,
|
||||
executable: usize,
|
||||
current: PtrLen,
|
||||
position: usize,
|
||||
}
|
||||
|
||||
impl Memory {
|
||||
pub fn new() -> Self {
|
||||
let mmap = memmap::MmapMut::map_anon(len as usize).unwrap();
|
||||
Self {
|
||||
allocations: Vec::new(),
|
||||
executable: 0,
|
||||
current: PtrLen::new(),
|
||||
position: 0,
|
||||
mmap,
|
||||
current: initial,
|
||||
maximum,
|
||||
}
|
||||
}
|
||||
|
||||
fn finish_current(&mut self) {
|
||||
self.allocations
|
||||
.push(mem::replace(&mut self.current, PtrLen::new()));
|
||||
self.position = 0;
|
||||
/// Returns an base address of this linear memory.
|
||||
pub fn base_addr(&mut self) -> *mut u8 {
|
||||
self.mmap.as_mut_ptr()
|
||||
}
|
||||
|
||||
/// TODO: Use a proper error type.
|
||||
pub fn allocate(&mut self, size: usize) -> Result<*mut u8, String> {
|
||||
if size <= self.current.len - self.position {
|
||||
// TODO: Ensure overflow is not possible.
|
||||
let ptr = unsafe { self.current.ptr.offset(self.position as isize) };
|
||||
self.position += size;
|
||||
return Ok(ptr);
|
||||
}
|
||||
|
||||
self.finish_current();
|
||||
|
||||
// TODO: Allocate more at a time.
|
||||
self.current = PtrLen::with_size(size)?;
|
||||
self.position = size;
|
||||
Ok(self.current.ptr)
|
||||
/// Returns a number of allocated wasm pages.
|
||||
pub fn current_size(&self) -> u32 {
|
||||
self.current
|
||||
}
|
||||
|
||||
/// Set all memory allocated in this `Memory` up to now as readable and executable.
|
||||
pub fn set_readable_and_executable(&mut self) {
|
||||
self.finish_current();
|
||||
|
||||
for &PtrLen { ptr, len } in &self.allocations[self.executable..] {
|
||||
if len != 0 {
|
||||
unsafe {
|
||||
region::protect(ptr, len, region::Protection::ReadExecute)
|
||||
.expect("unable to make memory readable+executable");
|
||||
}
|
||||
/// Grow memory by the specified amount of pages.
|
||||
///
|
||||
/// Returns `None` if memory can't be grown by the specified amount
|
||||
/// of pages.
|
||||
pub fn grow(&mut self, add_pages: u32) -> Option<u32> {
|
||||
let new_pages = match self.current.checked_add(add_pages) {
|
||||
Some(new_pages) => new_pages,
|
||||
None => return None,
|
||||
};
|
||||
if let Some(val) = self.maximum {
|
||||
if new_pages > val {
|
||||
return None;
|
||||
}
|
||||
} else {
|
||||
// Wasm linear memories are never allowed to grow beyond what is
|
||||
// indexable. If the memory has no maximum, enforce the greatest
|
||||
// limit here.
|
||||
if new_pages >= 65536 {
|
||||
return None;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Set all memory allocated in this `Memory` up to now as readonly.
|
||||
pub fn set_readonly(&mut self) {
|
||||
self.finish_current();
|
||||
let prev_pages = self.current;
|
||||
let new_bytes = (new_pages * PAGE_SIZE) as usize;
|
||||
|
||||
for &PtrLen { ptr, len } in &self.allocations[self.executable..] {
|
||||
if len != 0 {
|
||||
unsafe {
|
||||
region::protect(ptr, len, region::Protection::Read)
|
||||
.expect("unable to make memory readonly");
|
||||
}
|
||||
}
|
||||
if self.mmap.len() < new_bytes {
|
||||
// If we have no maximum, this is a "dynamic" heap, and it's allowed
|
||||
// to move.
|
||||
assert!(self.maximum.is_none());
|
||||
let mut new_mmap = memmap::MmapMut::map_anon(new_bytes).unwrap();
|
||||
new_mmap.copy_from_slice(&self.mmap);
|
||||
self.mmap = new_mmap;
|
||||
}
|
||||
|
||||
self.current = new_pages;
|
||||
|
||||
// Ensure that newly allocated area is zeroed.
|
||||
let new_start_offset = (prev_pages * PAGE_SIZE) as usize;
|
||||
let new_end_offset = (new_pages * PAGE_SIZE) as usize;
|
||||
for i in new_start_offset..new_end_offset {
|
||||
assert!(self.mmap[i] == 0);
|
||||
}
|
||||
|
||||
Some(prev_pages)
|
||||
}
|
||||
}
|
||||
|
||||
// TODO: Implement Drop to unprotect and deallocate the memory?
|
||||
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
use super::*;
|
||||
|
||||
#[test]
|
||||
fn test_round_up_to_page_size() {
|
||||
assert_eq!(round_up_to_page_size(0, 4096), 0);
|
||||
assert_eq!(round_up_to_page_size(1, 4096), 4096);
|
||||
assert_eq!(round_up_to_page_size(4096, 4096), 4096);
|
||||
assert_eq!(round_up_to_page_size(4097, 4096), 8192);
|
||||
impl fmt::Debug for LinearMemory {
|
||||
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
||||
f.debug_struct("LinearMemory")
|
||||
.field("current", &self.current)
|
||||
.field("maximum", &self.maximum)
|
||||
.finish()
|
||||
}
|
||||
}
|
||||
|
||||
impl AsRef<[u8]> for LinearMemory {
|
||||
fn as_ref(&self) -> &[u8] {
|
||||
&self.mmap
|
||||
}
|
||||
}
|
||||
|
||||
impl AsMut<[u8]> for LinearMemory {
|
||||
fn as_mut(&mut self) -> &mut [u8] {
|
||||
&mut self.mmap
|
||||
}
|
||||
}
|
||||
|
||||
Reference in New Issue
Block a user