Von-Neumann?

hbvm/fuzz/Cargo.toml

@@ -13,6 +13,9 @@ libfuzzer-sys = "0.4"
 [dependencies.hbvm]
 path = ".."
 
+[dependencies.hbbytecode]
+path = "../../hbbytecode"
+
 # Prevent this from interfering with workspaces
 [workspace]
 members = ["."]

hbvm/fuzz/fuzz_targets/vm.rs

@@ -1,15 +1,30 @@
 #![no_main]
 
 use {
+    hbbytecode::valider::validate,
     hbvm::{
-        mem::{HandlePageFault, Memory, MemoryAccessReason, PageSize},
+        softpaging::{
-        Vm,
+            paging::{PageTable, Permission},
+            HandlePageFault, PageSize, SoftPagedMem,
+        },
+        MemoryAccessReason, Vm,
     },
     libfuzzer_sys::fuzz_target,
 };
 
 fuzz_target!(|data: &[u8]| {
-    if let Ok(mut vm) = Vm::<_, 16384>::new_validated(data, TestTrapHandler, Default::default()) {
+    if validate(data).is_ok() {
+        let mut vm = unsafe {
+            Vm::<_, 16384>::new(
+                SoftPagedMem {
+                    pf_handler: TestTrapHandler,
+                    program:    data,
+                    root_pt:    Box::into_raw(Default::default()),
+                },
+                0,
+            )
+        };
+
         // Alloc and map some memory
         let pages = [
             alloc_and_map(&mut vm.memory, 0),
@@ -26,22 +41,17 @@ fuzz_target!(|data: &[u8]| {
     }
 });
 
-fn alloc_and_map(memory: &mut Memory, at: u64) -> *mut u8 {
+fn alloc_and_map(memory: &mut SoftPagedMem<TestTrapHandler>, at: u64) -> *mut u8 {
     let ptr = Box::into_raw(Box::<Page>::default()).cast();
     unsafe {
         memory
-            .map(
+            .map(ptr, at, Permission::Write, PageSize::Size4K)
-                ptr,
-                at,
-                hbvm::mem::paging::Permission::Write,
-                PageSize::Size4K,
-            )
             .unwrap()
     };
     ptr
 }
 
-fn unmap_and_dealloc(memory: &mut Memory, ptr: *mut u8, from: u64) {
+fn unmap_and_dealloc(memory: &mut SoftPagedMem<TestTrapHandler>, ptr: *mut u8, from: u64) {
     memory.unmap(from).unwrap();
     let _ = unsafe { Box::from_raw(ptr.cast::<Page>()) };
 }
@@ -59,7 +69,7 @@ impl HandlePageFault for TestTrapHandler {
     fn page_fault(
         &mut self,
         _: MemoryAccessReason,
-        _: &mut Memory,
+        _: &mut PageTable,
         _: u64,
         _: PageSize,
         _: *mut u8,

hbvm/src/lib.rs

@@ -14,8 +14,6 @@
 #![cfg_attr(feature = "nightly", feature(fn_align))]
 #![warn(missing_docs, clippy::missing_docs_in_private_items)]
 
-use core::marker::PhantomData;
-
 #[cfg(feature = "alloc")]
 extern crate alloc;
 
@@ -26,16 +24,14 @@ mod bmc;
 
 use {
     bmc::BlockCopier,
-    core::{cmp::Ordering, mem::size_of, ops},
+    core::{cmp::Ordering, mem::size_of, ops, slice::SliceIndex},
     derive_more::Display,
-    hbbytecode::{
+    hbbytecode::{OpParam, ParamBB, ParamBBB, ParamBBBB, ParamBBD, ParamBBDH, ParamBBW, ParamBD},
-        valider, OpParam, ParamBB, ParamBBB, ParamBBBB, ParamBBD, ParamBBDH, ParamBBW, ParamBD,
-    },
     value::{Value, ValueVariant},
 };
 
 /// HoleyBytes Virtual Machine
-pub struct Vm<'a, Mem, const TIMER_QUOTIENT: usize> {
+pub struct Vm<Mem, const TIMER_QUOTIENT: usize> {
     /// Holds 256 registers
     ///
     /// Writing to register 0 is considered undefined behaviour
@@ -48,15 +44,6 @@ pub struct Vm<'a, Mem, const TIMER_QUOTIENT: usize> {
     /// Program counter
     pub pc: usize,
 
-    /// Program
-    program: *const u8,
-
-    /// Cached program length (without unreachable end)
-    program_len: usize,
-
-    /// Program lifetime
-    _program_lt: PhantomData<&'a [u8]>,
-
     /// Program timer
     timer: usize,
 
@@ -64,7 +51,7 @@ pub struct Vm<'a, Mem, const TIMER_QUOTIENT: usize> {
     copier: Option<BlockCopier>,
 }
 
-impl<'a, Mem, const TIMER_QUOTIENT: usize> Vm<'a, Mem, TIMER_QUOTIENT>
+impl<Mem, const TIMER_QUOTIENT: usize> Vm<Mem, TIMER_QUOTIENT>
 where
     Mem: Memory,
 {
@@ -72,25 +59,16 @@ where
     ///
     /// # Safety
     /// Program code has to be validated
-    pub unsafe fn new_unchecked(program: &'a [u8], memory: Mem) -> Self {
+    pub unsafe fn new(memory: Mem, entry: u64) -> Self {
         Self {
             registers: [Value::from(0_u64); 256],
             memory,
-            pc: 0,
+            pc: entry as _,
-            program_len: program.len() - 12,
-            program: program[4..].as_ptr(),
-            _program_lt: Default::default(),
             timer: 0,
             copier: None,
         }
     }
 
-    /// Create a new VM with program and trap handler only if it passes validation
-    pub fn new_validated(program: &'a [u8], memory: Mem) -> Result<Self, valider::Error> {
-        valider::validate(program)?;
-        Ok(unsafe { Self::new_unchecked(program, memory) })
-    }
-
     /// Execute program
     ///
     /// Program can return [`VmRunError`] if a trap handling failed
@@ -98,11 +76,6 @@ where
     pub fn run(&mut self) -> Result<VmRunOk, VmRunError> {
         use hbbytecode::opcode::*;
         loop {
-            // Check instruction boundary
-            if self.pc >= self.program_len {
-                return Err(VmRunError::AddrOutOfBounds);
-            }
-
             // Big match
             //
             // Contribution guide:
@@ -123,7 +96,11 @@ where
             // - Yes, we assume you run 64 bit CPU. Else ?conradluget a better CPU
             //   sorry 8 bit fans, HBVM won't run on your Speccy :(
             unsafe {
-                match *self.program.add(self.pc) {
+                match *self
+                    .memory
+                    .load_prog(self.pc)
+                    .ok_or(VmRunError::ProgramFetchLoadEx(self.pc as _))?
+                {
                     UN => {
                         self.decode::<()>();
                         return Err(VmRunError::Unreachable);
@@ -388,15 +365,22 @@ where
     }
 
     /// Decode instruction operands
-    #[inline]
+    #[inline(always)]
     unsafe fn decode<T: OpParam>(&mut self) -> T {
-        let data = self.program.add(self.pc + 1).cast::<T>().read();
+        let pc1 = self.pc + 1;
+        let data = self
+            .memory
+            .load_prog_unchecked(pc1..pc1 + size_of::<T>())
+            .as_ptr()
+            .cast::<T>()
+            .read();
+
         self.pc += 1 + size_of::<T>();
         data
     }
 
     /// Perform binary operating over two registers
-    #[inline]
+    #[inline(always)]
     unsafe fn binary_op<T: ValueVariant>(&mut self, op: impl Fn(T, T) -> T) {
         let ParamBBB(tg, a0, a1) = self.decode();
         self.write_reg(
@@ -406,7 +390,7 @@ where
     }
 
     /// Perform binary operation over register and immediate
-    #[inline]
+    #[inline(always)]
     unsafe fn binary_op_imm<T: ValueVariant>(&mut self, op: impl Fn(T, T) -> T) {
         let ParamBBD(tg, reg, imm) = self.decode();
         self.write_reg(
@@ -416,14 +400,14 @@ where
     }
 
     /// Perform binary operation over register and shift immediate
-    #[inline]
+    #[inline(always)]
     unsafe fn binary_op_ims<T: ValueVariant>(&mut self, op: impl Fn(T, u32) -> T) {
         let ParamBBW(tg, reg, imm) = self.decode();
         self.write_reg(tg, op(self.read_reg(reg).cast::<T>(), imm));
     }
 
     /// Jump at `#3` if ordering on `#0 <=> #1` is equal to expected
-    #[inline]
+    #[inline(always)]
     unsafe fn cond_jmp<T: ValueVariant + Ord>(&mut self, expected: Ordering) {
         let ParamBBD(a0, a1, ja) = self.decode();
         if self
@@ -437,14 +421,14 @@ where
     }
 
     /// Read register
-    #[inline]
+    #[inline(always)]
     unsafe fn read_reg(&self, n: u8) -> Value {
         *self.registers.get_unchecked(n as usize)
     }
 
     /// Write a register.
     /// Writing to register 0 is no-op.
-    #[inline]
+    #[inline(always)]
     unsafe fn write_reg(&mut self, n: u8, value: impl Into<Value>) {
         if n != 0 {
             *self.registers.get_unchecked_mut(n as usize) = value.into();
@@ -452,7 +436,7 @@ where
     }
 
     /// Load / Store Address check-computation überfunction
-    #[inline]
+    #[inline(always)]
     unsafe fn ldst_addr_uber(
         &self,
         dst: u8,
@@ -485,6 +469,9 @@ pub enum VmRunError {
     /// Unhandled load access exception
     LoadAccessEx(u64),
 
+    /// Unhandled instruction load access exception
+    ProgramFetchLoadEx(u64),
+
     /// Unhandled store access exception
     StoreAccessEx(u64),
 
@@ -529,6 +516,40 @@ pub trait Memory {
         source: *const u8,
         count: usize,
     ) -> Result<(), StoreError>;
+
+    /// Fetch bytes from program section
+    ///
+    /// # Why?
+    /// Even Holey Bytes programs operate with
+    /// single address space, the actual implementation
+    /// may be different, so for these reasons there is a
+    /// separate function.
+    ///
+    /// Also if your memory implementation differentiates between
+    /// readable and executable memory, this is the way to distinguish
+    /// the loads.
+    ///
+    /// # Notice for implementors
+    /// This is a hot function. This is called on each opcode fetch
+    /// and instruction decode. Inlining the implementation is highly
+    /// recommended!
+    ///
+    /// If you utilise some more heavy memory implementation, consider
+    /// performing caching as HBVM does not do that for you.
+    ///
+    /// Has to return all the requested data. If cannot fetch data of requested
+    /// length, return [`None`].
+    fn load_prog<I>(&mut self, index: I) -> Option<&I::Output>
+    where
+        I: SliceIndex<[u8]>;
+
+    /// Fetch bytes from program section, unchecked.
+    ///
+    /// # Safety
+    /// You really have to be sure you get the bytes, got me?
+    unsafe fn load_prog_unchecked<I>(&mut self, index: I) -> &I::Output
+    where
+        I: SliceIndex<[u8]>;
 }
 
 /// Unhandled load access trap

hbvm/src/main.rs

@@ -10,15 +10,20 @@ use {
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     let mut prog = vec![];
     stdin().read_to_end(&mut prog)?;
-    println!("{prog:?}");
 
     if let Err(e) = validate(&prog) {
         eprintln!("Program validation error: {e:?}");
         return Ok(());
     } else {
         unsafe {
-            let mut vm =
+            let mut vm = Vm::<_, 0>::new(
-                Vm::<_, 0>::new_unchecked(&prog, SoftPagedMem::<TestTrapHandler>::default());
+                SoftPagedMem {
+                    pf_handler: TestTrapHandler,
+                    program:    &prog,
+                    root_pt:    Box::into_raw(Default::default()),
+                },
+                0,
+            );
             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(())

hbvm/src/softpaging/mod.rs

@@ -4,6 +4,7 @@ pub mod paging;
 
 use {
     super::{LoadError, Memory, MemoryAccessReason, StoreError},
+    core::slice::SliceIndex,
     derive_more::Display,
     paging::{PageTable, Permission},
 };
@@ -13,14 +14,16 @@ 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 +60,27 @@ 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
@@ -239,24 +260,14 @@ impl Iterator for AddrPageLookuper {
 }
 
 #[cfg(feature = "alloc")]
-impl<PfHandler: Default> Default for SoftPagedMem<PfHandler> {
+impl<'p, A> Drop for SoftPagedMem<'p, A> {
-    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> {
+impl<'p, A> SoftPagedMem<'p, A> {
     /// Maps host's memory into VM's memory
     ///
     /// # Safety