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use crate::{backend::RunnableModule, module::ModuleInfo, types::Value, vm::Ctx}; #[cfg(unix)] use libc::{mmap, mprotect, munmap, MAP_ANON, MAP_PRIVATE, PROT_EXEC, PROT_READ, PROT_WRITE}; use std::{ fmt::Debug, ops::{Deref, DerefMut}, }; pub trait Loader { type Instance: Instance; type Error: Debug; fn load( &self, rm: &dyn RunnableModule, module: &ModuleInfo, ctx: &Ctx, ) -> Result<Self::Instance, Self::Error>; } pub trait Instance { type Error: Debug; fn call(&mut self, id: usize, args: &[Value]) -> Result<u64, Self::Error>; fn read_memory(&mut self, _offset: u32, _len: u32) -> Result<Vec<u8>, Self::Error> { unimplemented!() } fn write_memory(&mut self, _offset: u32, _len: u32, _buf: &[u8]) -> Result<(), Self::Error> { unimplemented!() } } pub struct LocalLoader; impl Loader for LocalLoader { type Instance = LocalInstance; type Error = String; fn load( &self, rm: &dyn RunnableModule, _module: &ModuleInfo, _ctx: &Ctx, ) -> Result<Self::Instance, Self::Error> { let code = rm.get_code().unwrap(); let mut code_mem = CodeMemory::new(code.len()); code_mem[..code.len()].copy_from_slice(code); code_mem.make_executable(); Ok(LocalInstance { code: code_mem, offsets: rm.get_offsets().unwrap(), }) } } pub struct LocalInstance { code: CodeMemory, offsets: Vec<usize>, } impl Instance for LocalInstance { type Error = String; fn call(&mut self, id: usize, args: &[Value]) -> Result<u64, Self::Error> { let offset = self.offsets[id]; let addr: *const u8 = unsafe { self.code.as_ptr().offset(offset as isize) }; use std::mem::transmute; Ok(unsafe { match args.len() { 0 => (transmute::<_, extern "C" fn() -> u64>(addr))(), 1 => (transmute::<_, extern "C" fn(u64) -> u64>(addr))(args[0].to_u64()), 2 => (transmute::<_, extern "C" fn(u64, u64) -> u64>(addr))( args[0].to_u64(), args[1].to_u64(), ), 3 => (transmute::<_, extern "C" fn(u64, u64, u64) -> u64>(addr))( args[0].to_u64(), args[1].to_u64(), args[2].to_u64(), ), 4 => (transmute::<_, extern "C" fn(u64, u64, u64, u64) -> u64>(addr))( args[0].to_u64(), args[1].to_u64(), args[2].to_u64(), args[3].to_u64(), ), 5 => (transmute::<_, extern "C" fn(u64, u64, u64, u64, u64) -> u64>(addr))( args[0].to_u64(), args[1].to_u64(), args[2].to_u64(), args[3].to_u64(), args[4].to_u64(), ), _ => return Err("too many arguments".into()), } }) } } pub struct CodeMemory { ptr: *mut u8, size: usize, } #[cfg(not(unix))] impl CodeMemory { pub fn new(_size: usize) -> CodeMemory { unimplemented!(); } pub fn make_executable(&mut self) { unimplemented!(); } } #[cfg(unix)] impl CodeMemory { pub fn new(size: usize) -> CodeMemory { fn round_up_to_page_size(size: usize) -> usize { (size + (4096 - 1)) & !(4096 - 1) } let size = round_up_to_page_size(size); let ptr = unsafe { mmap( ::std::ptr::null_mut(), size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0, ) }; if ptr as isize == -1 { panic!("cannot allocate code memory"); } CodeMemory { ptr: ptr as _, size: size, } } pub fn make_executable(&mut self) { if unsafe { mprotect(self.ptr as _, self.size, PROT_READ | PROT_EXEC) } != 0 { panic!("cannot set code memory to executable"); } } } #[cfg(unix)] impl Drop for CodeMemory { fn drop(&mut self) { unsafe { munmap(self.ptr as _, self.size); } } } impl Deref for CodeMemory { type Target = [u8]; fn deref(&self) -> &[u8] { unsafe { ::std::slice::from_raw_parts(self.ptr, self.size) } } } impl DerefMut for CodeMemory { fn deref_mut(&mut self) -> &mut [u8] { unsafe { ::std::slice::from_raw_parts_mut(self.ptr, self.size) } } }