forked from AbleOS/holey-bytes
Some merges
This commit is contained in:
commit
7dc8c6cca4
7
Cargo.lock
generated
7
Cargo.lock
generated
|
@ -127,7 +127,6 @@ dependencies = [
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"delegate",
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"derive_more",
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"hbbytecode",
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"log",
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"paste",
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"sealed",
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"static_assertions",
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@ -169,12 +168,6 @@ dependencies = [
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"proc-macro2",
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]
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[[package]]
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name = "log"
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version = "0.4.19"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "b06a4cde4c0f271a446782e3eff8de789548ce57dbc8eca9292c27f4a42004b4"
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[[package]]
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name = "logos"
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version = "0.13.0"
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@ -15,7 +15,6 @@ nightly = []
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delegate = "0.9"
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derive_more = "0.99"
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hbbytecode.path = "../hbbytecode"
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log = "0.4"
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paste = "1.0"
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sealed = "0.5"
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static_assertions = "1.0"
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@ -13,6 +13,9 @@ libfuzzer-sys = "0.4"
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[dependencies.hbvm]
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path = ".."
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[dependencies.hbbytecode]
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path = "../../hbbytecode"
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# Prevent this from interfering with workspaces
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[workspace]
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members = ["."]
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@ -1,15 +1,30 @@
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#![no_main]
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use {
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hbbytecode::valider::validate,
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hbvm::{
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mem::{HandlePageFault, Memory, MemoryAccessReason, PageSize},
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Vm,
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softpaging::{
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paging::{PageTable, Permission},
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HandlePageFault, PageSize, SoftPagedMem,
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},
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MemoryAccessReason, Vm,
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},
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libfuzzer_sys::fuzz_target,
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};
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fuzz_target!(|data: &[u8]| {
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if let Ok(mut vm) = Vm::<_, 16384>::new_validated(data, TestTrapHandler, Default::default()) {
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if validate(data).is_ok() {
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let mut vm = unsafe {
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Vm::<_, 16384>::new(
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SoftPagedMem {
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pf_handler: TestTrapHandler,
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program: data,
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root_pt: Box::into_raw(Default::default()),
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},
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0,
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)
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};
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// Alloc and map some memory
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let pages = [
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alloc_and_map(&mut vm.memory, 0),
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@ -26,22 +41,17 @@ fuzz_target!(|data: &[u8]| {
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}
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});
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fn alloc_and_map(memory: &mut Memory, at: u64) -> *mut u8 {
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fn alloc_and_map(memory: &mut SoftPagedMem<TestTrapHandler>, at: u64) -> *mut u8 {
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let ptr = Box::into_raw(Box::<Page>::default()).cast();
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unsafe {
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memory
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.map(
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ptr,
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at,
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hbvm::mem::paging::Permission::Write,
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PageSize::Size4K,
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)
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.map(ptr, at, Permission::Write, PageSize::Size4K)
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.unwrap()
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};
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ptr
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}
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fn unmap_and_dealloc(memory: &mut Memory, ptr: *mut u8, from: u64) {
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fn unmap_and_dealloc(memory: &mut SoftPagedMem<TestTrapHandler>, ptr: *mut u8, from: u64) {
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memory.unmap(from).unwrap();
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let _ = unsafe { Box::from_raw(ptr.cast::<Page>()) };
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}
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@ -59,7 +69,7 @@ impl HandlePageFault for TestTrapHandler {
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fn page_fault(
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&mut self,
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_: MemoryAccessReason,
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_: &mut Memory,
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_: &mut PageTable,
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_: u64,
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_: PageSize,
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_: *mut u8,
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|
|
107
hbvm/src/lib.rs
107
hbvm/src/lib.rs
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@ -14,8 +14,6 @@
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#![cfg_attr(feature = "nightly", feature(fn_align))]
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#![warn(missing_docs, clippy::missing_docs_in_private_items)]
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use core::marker::PhantomData;
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#[cfg(feature = "alloc")]
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extern crate alloc;
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@ -26,16 +24,14 @@ mod bmc;
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use {
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bmc::BlockCopier,
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core::{cmp::Ordering, mem::size_of, ops},
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core::{cmp::Ordering, mem::size_of, ops, slice::SliceIndex},
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derive_more::Display,
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hbbytecode::{
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valider, OpParam, ParamBB, ParamBBB, ParamBBBB, ParamBBD, ParamBBDH, ParamBBW, ParamBD,
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},
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hbbytecode::{OpParam, ParamBB, ParamBBB, ParamBBBB, ParamBBD, ParamBBDH, ParamBBW, ParamBD},
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value::{Value, ValueVariant},
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};
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/// HoleyBytes Virtual Machine
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pub struct Vm<'a, Mem, const TIMER_QUOTIENT: usize> {
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pub struct Vm<Mem, const TIMER_QUOTIENT: usize> {
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/// Holds 256 registers
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///
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/// Writing to register 0 is considered undefined behaviour
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@ -48,15 +44,6 @@ pub struct Vm<'a, Mem, const TIMER_QUOTIENT: usize> {
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/// Program counter
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pub pc: usize,
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/// Program
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program: *const u8,
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/// Cached program length (without unreachable end)
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program_len: usize,
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/// Program lifetime
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_program_lt: PhantomData<&'a [u8]>,
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/// Program timer
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timer: usize,
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@ -64,7 +51,7 @@ pub struct Vm<'a, Mem, const TIMER_QUOTIENT: usize> {
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copier: Option<BlockCopier>,
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}
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impl<'a, Mem, const TIMER_QUOTIENT: usize> Vm<'a, Mem, TIMER_QUOTIENT>
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impl<Mem, const TIMER_QUOTIENT: usize> Vm<Mem, TIMER_QUOTIENT>
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where
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Mem: Memory,
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{
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@ -72,25 +59,16 @@ where
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///
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/// # Safety
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/// Program code has to be validated
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pub unsafe fn new_unchecked(program: &'a [u8], memory: Mem) -> Self {
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pub unsafe fn new(memory: Mem, entry: u64) -> Self {
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Self {
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registers: [Value::from(0_u64); 256],
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memory,
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pc: 0,
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program_len: program.len() - 12,
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program: program[4..].as_ptr(),
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_program_lt: Default::default(),
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pc: entry as _,
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timer: 0,
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copier: None,
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}
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}
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/// Create a new VM with program and trap handler only if it passes validation
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pub fn new_validated(program: &'a [u8], memory: Mem) -> Result<Self, valider::Error> {
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valider::validate(program)?;
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Ok(unsafe { Self::new_unchecked(program, memory) })
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}
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/// Execute program
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///
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/// Program can return [`VmRunError`] if a trap handling failed
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@ -98,11 +76,6 @@ where
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pub fn run(&mut self) -> Result<VmRunOk, VmRunError> {
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use hbbytecode::opcode::*;
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loop {
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// Check instruction boundary
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if self.pc >= self.program_len {
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return Err(VmRunError::AddrOutOfBounds);
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}
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// Big match
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//
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// Contribution guide:
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@ -123,7 +96,11 @@ where
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// - Yes, we assume you run 64 bit CPU. Else ?conradluget a better CPU
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// sorry 8 bit fans, HBVM won't run on your Speccy :(
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unsafe {
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match *self.program.add(self.pc) {
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match *self
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.memory
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.load_prog(self.pc)
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.ok_or(VmRunError::ProgramFetchLoadEx(self.pc as _))?
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{
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UN => {
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self.decode::<()>();
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return Err(VmRunError::Unreachable);
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@ -388,15 +365,22 @@ where
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}
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/// Decode instruction operands
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#[inline]
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#[inline(always)]
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unsafe fn decode<T: OpParam>(&mut self) -> T {
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let data = self.program.add(self.pc + 1).cast::<T>().read();
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let pc1 = self.pc + 1;
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let data = self
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.memory
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.load_prog_unchecked(pc1..pc1 + size_of::<T>())
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.as_ptr()
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.cast::<T>()
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.read();
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self.pc += 1 + size_of::<T>();
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data
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}
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/// Perform binary operating over two registers
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#[inline]
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#[inline(always)]
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unsafe fn binary_op<T: ValueVariant>(&mut self, op: impl Fn(T, T) -> T) {
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let ParamBBB(tg, a0, a1) = self.decode();
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self.write_reg(
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@ -406,7 +390,7 @@ where
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}
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/// Perform binary operation over register and immediate
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#[inline]
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#[inline(always)]
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unsafe fn binary_op_imm<T: ValueVariant>(&mut self, op: impl Fn(T, T) -> T) {
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let ParamBBD(tg, reg, imm) = self.decode();
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self.write_reg(
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@ -416,14 +400,14 @@ where
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}
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/// Perform binary operation over register and shift immediate
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#[inline]
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#[inline(always)]
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unsafe fn binary_op_ims<T: ValueVariant>(&mut self, op: impl Fn(T, u32) -> T) {
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let ParamBBW(tg, reg, imm) = self.decode();
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self.write_reg(tg, op(self.read_reg(reg).cast::<T>(), imm));
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}
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/// Jump at `#3` if ordering on `#0 <=> #1` is equal to expected
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#[inline]
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#[inline(always)]
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unsafe fn cond_jmp<T: ValueVariant + Ord>(&mut self, expected: Ordering) {
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let ParamBBD(a0, a1, ja) = self.decode();
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if self
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@ -437,14 +421,14 @@ where
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}
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/// Read register
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#[inline]
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#[inline(always)]
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unsafe fn read_reg(&self, n: u8) -> Value {
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*self.registers.get_unchecked(n as usize)
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}
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/// Write a register.
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/// Writing to register 0 is no-op.
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#[inline]
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#[inline(always)]
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unsafe fn write_reg(&mut self, n: u8, value: impl Into<Value>) {
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if n != 0 {
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*self.registers.get_unchecked_mut(n as usize) = value.into();
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|
@ -452,7 +436,7 @@ where
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}
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/// Load / Store Address check-computation überfunction
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#[inline]
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#[inline(always)]
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unsafe fn ldst_addr_uber(
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&self,
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dst: u8,
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|
@ -485,6 +469,9 @@ pub enum VmRunError {
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/// Unhandled load access exception
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LoadAccessEx(u64),
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/// Unhandled instruction load access exception
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ProgramFetchLoadEx(u64),
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/// Unhandled store access exception
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StoreAccessEx(u64),
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|
@ -529,6 +516,40 @@ pub trait Memory {
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source: *const u8,
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count: usize,
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) -> Result<(), StoreError>;
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/// Fetch bytes from program section
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///
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/// # Why?
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/// Even Holey Bytes programs operate with
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/// single address space, the actual implementation
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/// may be different, so for these reasons there is a
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/// separate function.
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///
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/// Also if your memory implementation differentiates between
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/// readable and executable memory, this is the way to distinguish
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/// the loads.
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///
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/// # Notice for implementors
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/// This is a hot function. This is called on each opcode fetch
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/// and instruction decode. Inlining the implementation is highly
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/// recommended!
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///
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/// If you utilise some more heavy memory implementation, consider
|
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/// performing caching as HBVM does not do that for you.
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///
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/// Has to return all the requested data. If cannot fetch data of requested
|
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/// length, return [`None`].
|
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fn load_prog<I>(&mut self, index: I) -> Option<&I::Output>
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where
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I: SliceIndex<[u8]>;
|
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|
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/// Fetch bytes from program section, unchecked.
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///
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/// # Safety
|
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/// You really have to be sure you get the bytes, got me?
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unsafe fn load_prog_unchecked<I>(&mut self, index: I) -> &I::Output
|
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where
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I: SliceIndex<[u8]>;
|
||||
}
|
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|
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/// Unhandled load access trap
|
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|
|
|
@ -10,15 +10,20 @@ use {
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fn main() -> Result<(), Box<dyn std::error::Error>> {
|
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let mut prog = vec![];
|
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stdin().read_to_end(&mut prog)?;
|
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println!("{prog:?}");
|
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|
||||
if let Err(e) = validate(&prog) {
|
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eprintln!("Program validation error: {e:?}");
|
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return Ok(());
|
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} else {
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unsafe {
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let mut vm =
|
||||
Vm::<_, 0>::new_unchecked(&prog, SoftPagedMem::<TestTrapHandler>::default());
|
||||
let mut vm = Vm::<_, 0>::new(
|
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SoftPagedMem {
|
||||
pf_handler: TestTrapHandler,
|
||||
program: &prog,
|
||||
root_pt: Box::into_raw(Default::default()),
|
||||
},
|
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4,
|
||||
);
|
||||
let data = {
|
||||
let ptr = std::alloc::alloc_zeroed(std::alloc::Layout::from_size_align_unchecked(
|
||||
4096, 4096,
|
||||
|
@ -32,7 +37,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
|
|||
vm.memory
|
||||
.map(
|
||||
data,
|
||||
0,
|
||||
8192,
|
||||
hbvm::softpaging::paging::Permission::Write,
|
||||
PageSize::Size4K,
|
||||
)
|
||||
|
@ -46,7 +51,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
|
|||
data,
|
||||
std::alloc::Layout::from_size_align_unchecked(4096, 4096),
|
||||
);
|
||||
vm.memory.unmap(0).unwrap();
|
||||
vm.memory.unmap(8192).unwrap();
|
||||
}
|
||||
}
|
||||
Ok(())
|
||||
|
|
124
hbvm/src/softpaging/lookup.rs
Normal file
124
hbvm/src/softpaging/lookup.rs
Normal file
|
@ -0,0 +1,124 @@
|
|||
//! Address lookup
|
||||
|
||||
use super::{
|
||||
addr_extract_index,
|
||||
paging::{PageTable, Permission},
|
||||
PageSize,
|
||||
};
|
||||
|
||||
/// Good result from address split
|
||||
pub struct AddrPageLookupOk {
|
||||
/// Virtual address
|
||||
pub vaddr: u64,
|
||||
|
||||
/// Pointer to the start for perform operation
|
||||
pub ptr: *mut u8,
|
||||
|
||||
/// Size to the end of page / end of desired size
|
||||
pub size: usize,
|
||||
|
||||
/// Page permission
|
||||
pub perm: Permission,
|
||||
}
|
||||
|
||||
/// Errornous address split result
|
||||
pub struct AddrPageLookupError {
|
||||
/// Address of failure
|
||||
pub addr: u64,
|
||||
|
||||
/// Requested page size
|
||||
pub size: PageSize,
|
||||
}
|
||||
|
||||
/// Address splitter into pages
|
||||
pub struct AddrPageLookuper {
|
||||
/// Current address
|
||||
addr: u64,
|
||||
|
||||
/// Size left
|
||||
size: usize,
|
||||
|
||||
/// Page table
|
||||
pagetable: *const PageTable,
|
||||
}
|
||||
|
||||
impl AddrPageLookuper {
|
||||
/// Create a new page lookuper
|
||||
#[inline]
|
||||
pub const fn new(addr: u64, size: usize, pagetable: *const PageTable) -> Self {
|
||||
Self {
|
||||
addr,
|
||||
size,
|
||||
pagetable,
|
||||
}
|
||||
}
|
||||
|
||||
/// Bump address by size X
|
||||
pub fn bump(&mut self, page_size: PageSize) {
|
||||
self.addr += page_size as u64;
|
||||
self.size = self.size.saturating_sub(page_size as _);
|
||||
}
|
||||
}
|
||||
|
||||
impl Iterator for AddrPageLookuper {
|
||||
type Item = Result<AddrPageLookupOk, AddrPageLookupError>;
|
||||
|
||||
fn next(&mut self) -> Option<Self::Item> {
|
||||
// The end, everything is fine
|
||||
if self.size == 0 {
|
||||
return None;
|
||||
}
|
||||
|
||||
let (base, perm, size, offset) = 'a: {
|
||||
let mut current_pt = self.pagetable;
|
||||
|
||||
// Walk the page table
|
||||
for lvl in (0..5).rev() {
|
||||
// Get an entry
|
||||
unsafe {
|
||||
let entry = (*current_pt)
|
||||
.table
|
||||
.get_unchecked(addr_extract_index(self.addr, lvl));
|
||||
|
||||
let ptr = entry.ptr();
|
||||
match entry.permission() {
|
||||
// No page → page fault
|
||||
Permission::Empty => {
|
||||
return Some(Err(AddrPageLookupError {
|
||||
addr: self.addr,
|
||||
size: PageSize::from_lvl(lvl)?,
|
||||
}))
|
||||
}
|
||||
|
||||
// Node → proceed waking
|
||||
Permission::Node => current_pt = ptr as _,
|
||||
|
||||
// Leaf → return relevant data
|
||||
perm => {
|
||||
break 'a (
|
||||
// Pointer in host memory
|
||||
ptr as *mut u8,
|
||||
perm,
|
||||
PageSize::from_lvl(lvl)?,
|
||||
// In-page offset
|
||||
addr_extract_index(self.addr, lvl),
|
||||
);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
return None; // Reached the end (should not happen)
|
||||
};
|
||||
|
||||
// Get available byte count in the selected page with offset
|
||||
let avail = (size as usize - offset).clamp(0, self.size);
|
||||
self.bump(size);
|
||||
|
||||
Some(Ok(AddrPageLookupOk {
|
||||
vaddr: self.addr,
|
||||
ptr: unsafe { base.add(offset) }, // Return pointer to the start of region
|
||||
size: avail,
|
||||
perm,
|
||||
}))
|
||||
}
|
||||
}
|
162
hbvm/src/softpaging/mapping.rs
Normal file
162
hbvm/src/softpaging/mapping.rs
Normal file
|
@ -0,0 +1,162 @@
|
|||
//! Automatic memory mapping
|
||||
|
||||
use {
|
||||
super::{
|
||||
addr_extract_index,
|
||||
paging::{PageTable, Permission, PtEntry, PtPointedData},
|
||||
PageSize, SoftPagedMem,
|
||||
},
|
||||
alloc::boxed::Box,
|
||||
derive_more::Display,
|
||||
};
|
||||
|
||||
impl<'p, A> SoftPagedMem<'p, A> {
|
||||
/// Maps host's memory into VM's memory
|
||||
///
|
||||
/// # Safety
|
||||
/// - Your faith in the gods of UB
|
||||
/// - Addr-san claims it's fine but who knows is she isn't lying :ferrisSus:
|
||||
/// - Alright, Miri-sama is also fine with this, who knows why
|
||||
pub unsafe fn map(
|
||||
&mut self,
|
||||
host: *mut u8,
|
||||
target: u64,
|
||||
perm: Permission,
|
||||
pagesize: PageSize,
|
||||
) -> Result<(), MapError> {
|
||||
let mut current_pt = self.root_pt;
|
||||
|
||||
// Decide on what level depth are we going
|
||||
let lookup_depth = match pagesize {
|
||||
PageSize::Size4K => 0,
|
||||
PageSize::Size2M => 1,
|
||||
PageSize::Size1G => 2,
|
||||
};
|
||||
|
||||
// Walk pagetable levels
|
||||
for lvl in (lookup_depth + 1..5).rev() {
|
||||
let entry = (*current_pt)
|
||||
.table
|
||||
.get_unchecked_mut(addr_extract_index(target, lvl));
|
||||
|
||||
let ptr = entry.ptr();
|
||||
match entry.permission() {
|
||||
// Still not on target and already seeing empty entry?
|
||||
// No worries! Let's create one (allocates).
|
||||
Permission::Empty => {
|
||||
// Increase children count
|
||||
(*current_pt).childen += 1;
|
||||
|
||||
let table = Box::into_raw(Box::new(PtPointedData {
|
||||
pt: PageTable::default(),
|
||||
}));
|
||||
|
||||
core::ptr::write(entry, PtEntry::new(table, Permission::Node));
|
||||
current_pt = table as _;
|
||||
}
|
||||
// Continue walking
|
||||
Permission::Node => current_pt = ptr as _,
|
||||
|
||||
// There is some entry on place of node
|
||||
_ => return Err(MapError::PageOnNode),
|
||||
}
|
||||
}
|
||||
|
||||
let node = (*current_pt)
|
||||
.table
|
||||
.get_unchecked_mut(addr_extract_index(target, lookup_depth));
|
||||
|
||||
// Check if node is not mapped
|
||||
if node.permission() != Permission::Empty {
|
||||
return Err(MapError::AlreadyMapped);
|
||||
}
|
||||
|
||||
// Write entry
|
||||
(*current_pt).childen += 1;
|
||||
core::ptr::write(node, PtEntry::new(host.cast(), perm));
|
||||
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// Unmaps pages from VM's memory
|
||||
///
|
||||
/// If errors, it only means there is no entry to unmap and in most cases
|
||||
/// just should be ignored.
|
||||
pub fn unmap(&mut self, addr: u64) -> Result<(), NothingToUnmap> {
|
||||
let mut current_pt = self.root_pt;
|
||||
let mut page_tables = [core::ptr::null_mut(); 5];
|
||||
|
||||
// Walk page table in reverse
|
||||
for lvl in (0..5).rev() {
|
||||
let entry = unsafe {
|
||||
(*current_pt)
|
||||
.table
|
||||
.get_unchecked_mut(addr_extract_index(addr, lvl))
|
||||
};
|
||||
|
||||
let ptr = entry.ptr();
|
||||
match entry.permission() {
|
||||
// Nothing is there, throw an error, not critical!
|
||||
Permission::Empty => return Err(NothingToUnmap),
|
||||
// Node – Save to visited pagetables and continue walking
|
||||
Permission::Node => {
|
||||
page_tables[lvl as usize] = entry;
|
||||
current_pt = ptr as _
|
||||
}
|
||||
// Page entry – zero it out!
|
||||
// Zero page entry is completely valid entry with
|
||||
// empty permission - no UB here!
|
||||
_ => unsafe {
|
||||
core::ptr::write_bytes(entry, 0, 1);
|
||||
break;
|
||||
},
|
||||
}
|
||||
}
|
||||
|
||||
// Now walk in order visited page tables
|
||||
for entry in page_tables.into_iter() {
|
||||
// Level not visited, skip.
|
||||
if entry.is_null() {
|
||||
continue;
|
||||
}
|
||||
|
||||
unsafe {
|
||||
let children = &mut (*(*entry).ptr()).pt.childen;
|
||||
*children -= 1; // Decrease children count
|
||||
|
||||
// If there are no children, deallocate.
|
||||
if *children == 0 {
|
||||
let _ = Box::from_raw((*entry).ptr() as *mut PageTable);
|
||||
|
||||
// Zero visited entry
|
||||
core::ptr::write_bytes(entry, 0, 1);
|
||||
} else {
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
Ok(())
|
||||
}
|
||||
}
|
||||
|
||||
/// Error mapping
|
||||
#[derive(Clone, Copy, Display, Debug, PartialEq, Eq)]
|
||||
pub enum MapError {
|
||||
/// Entry was already mapped
|
||||
#[display(fmt = "There is already a page mapped on specified address")]
|
||||
AlreadyMapped,
|
||||
/// When walking a page entry was
|
||||
/// encounterd.
|
||||
#[display(fmt = "There was a page mapped on the way instead of node")]
|
||||
PageOnNode,
|
||||
}
|
||||
|
||||
/// There was no entry in page table to unmap
|
||||
///
|
||||
/// No worry, don't panic, nothing bad has happened,
|
||||
/// but if you are 120% sure there should be something,
|
||||
/// double-check your addresses.
|
||||
#[derive(Clone, Copy, Display, Debug)]
|
||||
#[display(fmt = "There was no entry to unmap")]
|
||||
pub struct NothingToUnmap;
|
|
@ -1,26 +1,31 @@
|
|||
//! Platform independent, software paged memory implementation
|
||||
|
||||
use self::lookup::{AddrPageLookupError, AddrPageLookupOk, AddrPageLookuper};
|
||||
|
||||
pub mod lookup;
|
||||
pub mod paging;
|
||||
|
||||
#[cfg(feature = "alloc")]
|
||||
pub mod mapping;
|
||||
|
||||
use {
|
||||
super::{LoadError, Memory, MemoryAccessReason, StoreError},
|
||||
derive_more::Display,
|
||||
core::slice::SliceIndex,
|
||||
paging::{PageTable, Permission},
|
||||
};
|
||||
|
||||
#[cfg(feature = "alloc")]
|
||||
use {alloc::boxed::Box, paging::PtEntry};
|
||||
|
||||
/// HoleyBytes software paged memory
|
||||
#[derive(Clone, Debug)]
|
||||
pub struct SoftPagedMem<PfHandler> {
|
||||
pub struct SoftPagedMem<'p, PfH> {
|
||||
/// Root page table
|
||||
pub root_pt: *mut PageTable,
|
||||
/// Page fault handler
|
||||
pub pf_handler: PfHandler,
|
||||
pub pf_handler: PfH,
|
||||
/// Program memory segment
|
||||
pub program: &'p [u8],
|
||||
}
|
||||
|
||||
impl<PfHandler: HandlePageFault> Memory for SoftPagedMem<PfHandler> {
|
||||
impl<'p, PfH: HandlePageFault> Memory for SoftPagedMem<'p, PfH> {
|
||||
/// Load value from an address
|
||||
///
|
||||
/// # Safety
|
||||
|
@ -57,9 +62,27 @@ impl<PfHandler: HandlePageFault> Memory for SoftPagedMem<PfHandler> {
|
|||
)
|
||||
.map_err(StoreError)
|
||||
}
|
||||
|
||||
/// Fetch slice from program memory section
|
||||
#[inline(always)]
|
||||
fn load_prog<I>(&mut self, index: I) -> Option<&I::Output>
|
||||
where
|
||||
I: SliceIndex<[u8]>,
|
||||
{
|
||||
self.program.get(index)
|
||||
}
|
||||
|
||||
/// Fetch slice from program memory section, unchecked!
|
||||
#[inline(always)]
|
||||
unsafe fn load_prog_unchecked<I>(&mut self, index: I) -> &I::Output
|
||||
where
|
||||
I: SliceIndex<[u8]>,
|
||||
{
|
||||
self.program.get_unchecked(index)
|
||||
}
|
||||
}
|
||||
|
||||
impl<PfHandler: HandlePageFault> SoftPagedMem<PfHandler> {
|
||||
impl<'p, PfH: HandlePageFault> SoftPagedMem<'p, PfH> {
|
||||
// Everyone behold, the holy function, the god of HBVM memory accesses!
|
||||
|
||||
/// Split address to pages, check their permissions and feed pointers with offset
|
||||
|
@ -76,6 +99,37 @@ impl<PfHandler: HandlePageFault> SoftPagedMem<PfHandler> {
|
|||
permission_check: fn(Permission) -> bool,
|
||||
action: fn(*mut u8, *mut u8, usize),
|
||||
) -> Result<(), u64> {
|
||||
// Memory load from program section
|
||||
let (src, len) = if src < self.program.len() as _ {
|
||||
// Allow only loads
|
||||
if reason != MemoryAccessReason::Load {
|
||||
return Err(src);
|
||||
}
|
||||
|
||||
// Determine how much data to copy from here
|
||||
let to_copy = len.clamp(0, self.program.len().saturating_sub(src as _));
|
||||
|
||||
// Perform action
|
||||
action(
|
||||
unsafe { self.program.as_ptr().add(src as _).cast_mut() },
|
||||
dst,
|
||||
to_copy,
|
||||
);
|
||||
|
||||
// Return shifted from what we've already copied
|
||||
(
|
||||
src.saturating_add(to_copy as _),
|
||||
len.saturating_sub(to_copy),
|
||||
)
|
||||
} else {
|
||||
(src, len) // Nothing weird!
|
||||
};
|
||||
|
||||
// Nothing to copy? Don't bother doing anything, bail.
|
||||
if len == 0 {
|
||||
return Ok(());
|
||||
}
|
||||
|
||||
// Create new splitter
|
||||
let mut pspl = AddrPageLookuper::new(src, len, self.root_pt);
|
||||
loop {
|
||||
|
@ -121,271 +175,6 @@ impl<PfHandler: HandlePageFault> SoftPagedMem<PfHandler> {
|
|||
}
|
||||
}
|
||||
|
||||
/// Good result from address split
|
||||
struct AddrPageLookupOk {
|
||||
/// Virtual address
|
||||
vaddr: u64,
|
||||
|
||||
/// Pointer to the start for perform operation
|
||||
ptr: *mut u8,
|
||||
|
||||
/// Size to the end of page / end of desired size
|
||||
size: usize,
|
||||
|
||||
/// Page permission
|
||||
perm: Permission,
|
||||
}
|
||||
|
||||
/// Errornous address split result
|
||||
struct AddrPageLookupError {
|
||||
/// Address of failure
|
||||
addr: u64,
|
||||
|
||||
/// Requested page size
|
||||
size: PageSize,
|
||||
}
|
||||
|
||||
/// Address splitter into pages
|
||||
struct AddrPageLookuper {
|
||||
/// Current address
|
||||
addr: u64,
|
||||
|
||||
/// Size left
|
||||
size: usize,
|
||||
|
||||
/// Page table
|
||||
pagetable: *const PageTable,
|
||||
}
|
||||
|
||||
impl AddrPageLookuper {
|
||||
/// Create a new page lookuper
|
||||
#[inline]
|
||||
pub const fn new(addr: u64, size: usize, pagetable: *const PageTable) -> Self {
|
||||
Self {
|
||||
addr,
|
||||
size,
|
||||
pagetable,
|
||||
}
|
||||
}
|
||||
|
||||
/// Bump address by size X
|
||||
fn bump(&mut self, page_size: PageSize) {
|
||||
self.addr += page_size as u64;
|
||||
self.size = self.size.saturating_sub(page_size as _);
|
||||
}
|
||||
}
|
||||
|
||||
impl Iterator for AddrPageLookuper {
|
||||
type Item = Result<AddrPageLookupOk, AddrPageLookupError>;
|
||||
|
||||
fn next(&mut self) -> Option<Self::Item> {
|
||||
// The end, everything is fine
|
||||
if self.size == 0 {
|
||||
return None;
|
||||
}
|
||||
|
||||
let (base, perm, size, offset) = 'a: {
|
||||
let mut current_pt = self.pagetable;
|
||||
|
||||
// Walk the page table
|
||||
for lvl in (0..5).rev() {
|
||||
// Get an entry
|
||||
unsafe {
|
||||
let entry = (*current_pt)
|
||||
.table
|
||||
.get_unchecked(addr_extract_index(self.addr, lvl));
|
||||
|
||||
let ptr = entry.ptr();
|
||||
match entry.permission() {
|
||||
// No page → page fault
|
||||
Permission::Empty => {
|
||||
return Some(Err(AddrPageLookupError {
|
||||
addr: self.addr,
|
||||
size: PageSize::from_lvl(lvl)?,
|
||||
}))
|
||||
}
|
||||
|
||||
// Node → proceed waking
|
||||
Permission::Node => current_pt = ptr as _,
|
||||
|
||||
// Leaf → return relevant data
|
||||
perm => {
|
||||
break 'a (
|
||||
// Pointer in host memory
|
||||
ptr as *mut u8,
|
||||
perm,
|
||||
PageSize::from_lvl(lvl)?,
|
||||
// In-page offset
|
||||
addr_extract_index(self.addr, lvl),
|
||||
);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
return None; // Reached the end (should not happen)
|
||||
};
|
||||
|
||||
// Get available byte count in the selected page with offset
|
||||
let avail = (size as usize - offset).clamp(0, self.size);
|
||||
self.bump(size);
|
||||
|
||||
Some(Ok(AddrPageLookupOk {
|
||||
vaddr: self.addr,
|
||||
ptr: unsafe { base.add(offset) }, // Return pointer to the start of region
|
||||
size: avail,
|
||||
perm,
|
||||
}))
|
||||
}
|
||||
}
|
||||
|
||||
#[cfg(feature = "alloc")]
|
||||
impl<PfHandler: Default> Default for SoftPagedMem<PfHandler> {
|
||||
fn default() -> Self {
|
||||
Self {
|
||||
root_pt: Box::into_raw(Default::default()),
|
||||
pf_handler: Default::default(),
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
#[cfg(feature = "alloc")]
|
||||
impl<A> Drop for SoftPagedMem<A> {
|
||||
fn drop(&mut self) {
|
||||
let _ = unsafe { Box::from_raw(self.root_pt) };
|
||||
}
|
||||
}
|
||||
|
||||
#[cfg(feature = "alloc")]
|
||||
impl<A> SoftPagedMem<A> {
|
||||
/// Maps host's memory into VM's memory
|
||||
///
|
||||
/// # Safety
|
||||
/// - Your faith in the gods of UB
|
||||
/// - Addr-san claims it's fine but who knows is she isn't lying :ferrisSus:
|
||||
/// - Alright, Miri-sama is also fine with this, who knows why
|
||||
pub unsafe fn map(
|
||||
&mut self,
|
||||
host: *mut u8,
|
||||
target: u64,
|
||||
perm: Permission,
|
||||
pagesize: PageSize,
|
||||
) -> Result<(), MapError> {
|
||||
let mut current_pt = self.root_pt;
|
||||
|
||||
// Decide on what level depth are we going
|
||||
let lookup_depth = match pagesize {
|
||||
PageSize::Size4K => 0,
|
||||
PageSize::Size2M => 1,
|
||||
PageSize::Size1G => 2,
|
||||
};
|
||||
|
||||
// Walk pagetable levels
|
||||
for lvl in (lookup_depth + 1..5).rev() {
|
||||
let entry = (*current_pt)
|
||||
.table
|
||||
.get_unchecked_mut(addr_extract_index(target, lvl));
|
||||
|
||||
let ptr = entry.ptr();
|
||||
match entry.permission() {
|
||||
// Still not on target and already seeing empty entry?
|
||||
// No worries! Let's create one (allocates).
|
||||
Permission::Empty => {
|
||||
// Increase children count
|
||||
(*current_pt).childen += 1;
|
||||
|
||||
let table = Box::into_raw(Box::new(paging::PtPointedData {
|
||||
pt: PageTable::default(),
|
||||
}));
|
||||
|
||||
core::ptr::write(entry, PtEntry::new(table, Permission::Node));
|
||||
current_pt = table as _;
|
||||
}
|
||||
// Continue walking
|
||||
Permission::Node => current_pt = ptr as _,
|
||||
|
||||
// There is some entry on place of node
|
||||
_ => return Err(MapError::PageOnNode),
|
||||
}
|
||||
}
|
||||
|
||||
let node = (*current_pt)
|
||||
.table
|
||||
.get_unchecked_mut(addr_extract_index(target, lookup_depth));
|
||||
|
||||
// Check if node is not mapped
|
||||
if node.permission() != Permission::Empty {
|
||||
return Err(MapError::AlreadyMapped);
|
||||
}
|
||||
|
||||
// Write entry
|
||||
(*current_pt).childen += 1;
|
||||
core::ptr::write(node, PtEntry::new(host.cast(), perm));
|
||||
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// Unmaps pages from VM's memory
|
||||
///
|
||||
/// If errors, it only means there is no entry to unmap and in most cases
|
||||
/// just should be ignored.
|
||||
pub fn unmap(&mut self, addr: u64) -> Result<(), NothingToUnmap> {
|
||||
let mut current_pt = self.root_pt;
|
||||
let mut page_tables = [core::ptr::null_mut(); 5];
|
||||
|
||||
// Walk page table in reverse
|
||||
for lvl in (0..5).rev() {
|
||||
let entry = unsafe {
|
||||
(*current_pt)
|
||||
.table
|
||||
.get_unchecked_mut(addr_extract_index(addr, lvl))
|
||||
};
|
||||
|
||||
let ptr = entry.ptr();
|
||||
match entry.permission() {
|
||||
// Nothing is there, throw an error, not critical!
|
||||
Permission::Empty => return Err(NothingToUnmap),
|
||||
// Node – Save to visited pagetables and continue walking
|
||||
Permission::Node => {
|
||||
page_tables[lvl as usize] = entry;
|
||||
current_pt = ptr as _
|
||||
}
|
||||
// Page entry – zero it out!
|
||||
// Zero page entry is completely valid entry with
|
||||
// empty permission - no UB here!
|
||||
_ => unsafe {
|
||||
core::ptr::write_bytes(entry, 0, 1);
|
||||
break;
|
||||
},
|
||||
}
|
||||
}
|
||||
|
||||
// Now walk in order visited page tables
|
||||
for entry in page_tables.into_iter() {
|
||||
// Level not visited, skip.
|
||||
if entry.is_null() {
|
||||
continue;
|
||||
}
|
||||
|
||||
unsafe {
|
||||
let children = &mut (*(*entry).ptr()).pt.childen;
|
||||
*children -= 1; // Decrease children count
|
||||
|
||||
// If there are no children, deallocate.
|
||||
if *children == 0 {
|
||||
let _ = Box::from_raw((*entry).ptr() as *mut PageTable);
|
||||
|
||||
// Zero visited entry
|
||||
core::ptr::write_bytes(entry, 0, 1);
|
||||
} else {
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
Ok(())
|
||||
}
|
||||
}
|
||||
|
||||
/// Extract index in page table on specified level
|
||||
///
|
||||
/// The level shall not be larger than 4, otherwise
|
||||
|
@ -420,27 +209,6 @@ impl PageSize {
|
|||
}
|
||||
}
|
||||
|
||||
/// Error mapping
|
||||
#[derive(Clone, Copy, Display, Debug, PartialEq, Eq)]
|
||||
pub enum MapError {
|
||||
/// Entry was already mapped
|
||||
#[display(fmt = "There is already a page mapped on specified address")]
|
||||
AlreadyMapped,
|
||||
/// When walking a page entry was
|
||||
/// encounterd.
|
||||
#[display(fmt = "There was a page mapped on the way instead of node")]
|
||||
PageOnNode,
|
||||
}
|
||||
|
||||
/// There was no entry in page table to unmap
|
||||
///
|
||||
/// No worry, don't panic, nothing bad has happened,
|
||||
/// but if you are 120% sure there should be something,
|
||||
/// double-check your addresses.
|
||||
#[derive(Clone, Copy, Display, Debug)]
|
||||
#[display(fmt = "There was no entry to unmap")]
|
||||
pub struct NothingToUnmap;
|
||||
|
||||
/// Permisison checks
|
||||
pub mod perm_check {
|
||||
use super::paging::Permission;
|
||||
|
@ -459,6 +227,12 @@ pub mod perm_check {
|
|||
pub const fn writable(perm: Permission) -> bool {
|
||||
matches!(perm, Permission::Write)
|
||||
}
|
||||
|
||||
/// Page is executable
|
||||
#[inline(always)]
|
||||
pub const fn executable(perm: Permission) -> bool {
|
||||
matches!(perm, Permission::Exec)
|
||||
}
|
||||
}
|
||||
|
||||
/// Handle VM traps
|
||||
|
|
4
spec.md
4
spec.md
|
@ -261,8 +261,10 @@
|
|||
|
||||
# Memory
|
||||
- Addresses are 64 bit
|
||||
- Address `0x0` is invalid and acessing it traps
|
||||
- Program should be in the same address space as all other data
|
||||
- Memory implementation is arbitrary
|
||||
- Address `0x0` may or may not be valid. Count with compilers
|
||||
considering it invalid!
|
||||
- In case of accessing invalid address:
|
||||
- Program shall trap (LoadAccessEx, StoreAccessEx) with parameter of accessed address
|
||||
- Value of register when trapped is undefined
|
||||
|
|
Loading…
Reference in a new issue