From a7cf5e4847b2a29fb7a101adce7c7a0778ef0036 Mon Sep 17 00:00:00 2001 From: Erin Date: Sun, 25 Jun 2023 00:16:14 +0200 Subject: [PATCH] Implemented traps --- Cargo.lock | 35 ++++ hbvm/Cargo.toml | 1 + hbvm/src/lib.rs | 17 -- hbvm/src/main.rs | 37 ++++- hbvm/src/validate.rs | 10 ++ hbvm/src/vm/mem/mod.rs | 329 ++++++++++++++++++++++++++++++-------- hbvm/src/vm/mem/paging.rs | 16 ++ hbvm/src/vm/mod.rs | 134 ++++++++++------ hbvm/src/vm/trap.rs | 33 ++++ hbvm/src/vm/value.rs | 11 +- 10 files changed, 481 insertions(+), 142 deletions(-) create mode 100644 hbvm/src/vm/trap.rs diff --git a/Cargo.lock b/Cargo.lock index ef2eeb3..6ab71b0 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -25,6 +25,12 @@ version = "1.0.0" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd" +[[package]] +name = "convert_case" +version = "0.4.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "6245d59a3e82a7fc217c5828a6692dbc6dfb63a0c8c90495621f7b9d79704a0e" + [[package]] name = "delegate" version = "0.9.0" @@ -36,6 +42,19 @@ dependencies = [ "syn 1.0.109", ] +[[package]] +name = "derive_more" +version = "0.99.17" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "4fb810d30a7c1953f91334de7244731fc3f3c10d7fe163338a35b9f640960321" +dependencies = [ + "convert_case", + "proc-macro2", + "quote", + "rustc_version", + "syn 1.0.109", +] + [[package]] name = "fnv" version = "1.0.7" @@ -70,6 +89,7 @@ name = "hbvm" version = "0.1.0" dependencies = [ "delegate", + "derive_more", "hashbrown", "hbbytecode", "log", @@ -163,6 +183,21 @@ version = "0.6.29" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "f162c6dd7b008981e4d40210aca20b4bd0f9b60ca9271061b07f78537722f2e1" +[[package]] +name = "rustc_version" +version = "0.4.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "bfa0f585226d2e68097d4f95d113b15b83a82e819ab25717ec0590d9584ef366" +dependencies = [ + "semver", +] + +[[package]] +name = "semver" +version = "1.0.17" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "bebd363326d05ec3e2f532ab7660680f3b02130d780c299bca73469d521bc0ed" + [[package]] name = "static_assertions" version = "1.1.0" diff --git a/hbvm/Cargo.toml b/hbvm/Cargo.toml index 739c62b..a6b6a50 100644 --- a/hbvm/Cargo.toml +++ b/hbvm/Cargo.toml @@ -8,6 +8,7 @@ lto = true [dependencies] delegate = "0.9" +derive_more = "0.99" hashbrown = "0.13" hbbytecode.path = "../hbbytecode" log = "0.4" diff --git a/hbvm/src/lib.rs b/hbvm/src/lib.rs index 013fdb2..e17bc2e 100644 --- a/hbvm/src/lib.rs +++ b/hbvm/src/lib.rs @@ -3,20 +3,3 @@ extern crate alloc; pub mod validate; pub mod vm; - -#[derive(Debug, PartialEq)] -pub enum RuntimeErrors { - InvalidOpcodePair(u8, u8), - RegisterTooSmall, - HostError(u64), - PageNotMapped(u64), - InvalidJumpAddress(u64), - InvalidSystemCall(u8), -} - -// If you solve the halting problem feel free to remove this -#[derive(PartialEq, Debug)] -pub enum HaltStatus { - Halted, - Running, -} diff --git a/hbvm/src/main.rs b/hbvm/src/main.rs index a136f59..255384e 100644 --- a/hbvm/src/main.rs +++ b/hbvm/src/main.rs @@ -1,3 +1,9 @@ +use hbvm::vm::{ + mem::{Memory, MemoryAccessReason, PageSize}, + trap::HandleTrap, + value::Value, +}; + use { hbvm::{validate::validate, vm::Vm}, std::io::{stdin, Read}, @@ -6,13 +12,13 @@ use { fn main() -> Result<(), Box> { let mut prog = vec![]; stdin().read_to_end(&mut prog)?; - + if let Err(e) = validate(&prog) { eprintln!("Program validation error: {e:?}"); return Ok(()); } else { unsafe { - let mut vm = Vm::new_unchecked(&prog); + let mut vm = Vm::new_unchecked(&prog, TestTrapHandler); vm.memory.insert_test_page(); println!("Program interrupt: {:?}", vm.run()); println!("{:?}", vm.registers); @@ -24,3 +30,30 @@ fn main() -> Result<(), Box> { pub fn time() -> u32 { 9 } + +struct TestTrapHandler; +impl HandleTrap for TestTrapHandler { + fn page_fault( + &mut self, + _: MemoryAccessReason, + _: &mut Memory, + _: u64, + _: PageSize, + _: *mut u8, + ) -> bool { + false + } + + fn invalid_op(&mut self, _: &mut [Value; 256], _: &mut usize, _: &mut Memory, _: u8) -> bool + where + Self: Sized, + { + false + } + + fn ecall(&mut self, _: &mut [Value; 256], _: &mut usize, _: &mut Memory) + where + Self: Sized, + { + } +} diff --git a/hbvm/src/validate.rs b/hbvm/src/validate.rs index 65a7fec..215df8f 100644 --- a/hbvm/src/validate.rs +++ b/hbvm/src/validate.rs @@ -1,21 +1,31 @@ +/// Program validation error kind #[derive(Clone, Copy, Debug, PartialEq, Eq)] pub enum ErrorKind { + /// Unknown opcode InvalidInstruction, + /// VM doesn't implement this valid opcode Unimplemented, + /// Attempted to copy over register boundary RegisterArrayOverflow, } +/// Error #[derive(Clone, Copy, Debug, PartialEq, Eq)] pub struct Error { + /// Kind pub kind: ErrorKind, + /// Location in bytecode pub index: usize, } +/// Perform bytecode validation. If it passes, the program should be +/// sound to execute. pub fn validate(mut program: &[u8]) -> Result<(), Error> { use hbbytecode::opcode::*; let start = program; loop { + // Match on instruction types and perform necessary checks program = match program { [] => return Ok(()), [LD..=ST, reg, _, _, _, _, _, _, _, _, _, count, ..] diff --git a/hbvm/src/vm/mem/mod.rs b/hbvm/src/vm/mem/mod.rs index 476f835..5de0db8 100644 --- a/hbvm/src/vm/mem/mod.rs +++ b/hbvm/src/vm/mem/mod.rs @@ -1,10 +1,16 @@ mod paging; -use self::paging::{PageTable, Permission, PtEntry}; -use alloc::boxed::Box; +use core::mem::MaybeUninit; +use self::paging::{PageTable, Permission, PtEntry}; +use super::{trap::HandleTrap, VmRunError}; +use alloc::boxed::Box; +use derive_more::Display; + +/// HoleyBytes virtual memory #[derive(Clone, Debug)] pub struct Memory { + /// Root page table root_pt: *mut PageTable, } @@ -47,13 +53,23 @@ impl Memory { entry = PtEntry::new(Box::into_raw(pt) as _, Permission::Node); } - self.root_pt_mut()[0] = entry; + (*self.root_pt)[0] = entry; } } /// Load value from an address - pub unsafe fn load(&self, addr: u64, target: *mut u8, count: usize) -> Result<(), ()> { + /// + /// # Safety + /// Applies same conditions as for [`core::ptr::copy_nonoverlapping`] + pub unsafe fn load( + &mut self, + addr: u64, + target: *mut u8, + count: usize, + traph: &mut impl HandleTrap, + ) -> Result<(), LoadError> { self.memory_access( + MemoryAccessReason::Load, addr, target, count, @@ -64,96 +80,193 @@ impl Memory { ) }, |src, dst, count| core::ptr::copy_nonoverlapping(src, dst, count), + traph, ) + .map_err(|_| LoadError) } /// Store value to an address - pub unsafe fn store(&mut self, addr: u64, source: *const u8, count: usize) -> Result<(), ()> { + /// + /// # Safety + /// Applies same conditions as for [`core::ptr::copy_nonoverlapping`] + pub unsafe fn store( + &mut self, + addr: u64, + source: *const u8, + count: usize, + traph: &mut impl HandleTrap, + ) -> Result<(), StoreError> { self.memory_access( + MemoryAccessReason::Store, addr, source.cast_mut(), count, |perm| perm == Permission::Write, |dst, src, count| core::ptr::copy_nonoverlapping(src, dst, count), + traph, ) + .map_err(|_| StoreError) } /// Copy a block of memory - pub unsafe fn block_copy(&mut self, src: u64, dst: u64, count: u64) -> Result<(), ()> { - let count = usize::try_from(count).expect("?conradluget a better CPU"); + /// + /// # Safety + /// - Same as for [`Self::load`] and [`Self::store`] + /// - Your faith in the gods of UB + /// - Addr-san claims it's fine but who knows is she isn't lying :ferrisSus: + pub unsafe fn block_copy( + &mut self, + src: u64, + dst: u64, + count: usize, + traph: &mut impl HandleTrap, + ) -> Result<(), MemoryAccessReason> { + // Yea, i know it is possible to do this more efficiently, but I am too lazy. - let mut srcs = PageSplitter::new(src, count, self.root_pt); - let mut dsts = PageSplitter::new(dst, count, self.root_pt); - let mut c_src = srcs.next().ok_or(())?; - let mut c_dst = dsts.next().ok_or(())?; + const STACK_BUFFER_SIZE: usize = 512; - loop { - let min_size = c_src.size.min(c_dst.size); + // Decide if to use stack-allocated buffer or to heap allocate + // Deallocation is again decided on size at the end of the function + let mut buf = MaybeUninit::<[u8; STACK_BUFFER_SIZE]>::uninit(); + let buf = if count <= STACK_BUFFER_SIZE { + buf.as_mut_ptr().cast() + } else { unsafe { - core::ptr::copy(c_src.ptr, c_dst.ptr, min_size); - } + let layout = core::alloc::Layout::from_size_align_unchecked(count, 1); + let ptr = alloc::alloc::alloc(layout); + if ptr.is_null() { + alloc::alloc::handle_alloc_error(layout); + } - match ( - match c_src.size.saturating_sub(min_size) { - 0 => srcs.next(), - size => Some(PageSplitResult { size, ..c_src }), - }, - match c_dst.size.saturating_sub(min_size) { - 0 => dsts.next(), - size => Some(PageSplitResult { size, ..c_dst }), - }, - ) { - (None, None) => return Ok(()), - (Some(src), Some(dst)) => (c_src, c_dst) = (src, dst), - _ => return Err(()), + ptr } + }; + + // Perform memory block transfer + let status = (|| { + // Load to buffer + self.memory_access( + MemoryAccessReason::Load, + src, + buf, + count, + |perm| { + matches!( + perm, + Permission::Readonly | Permission::Write | Permission::Exec + ) + }, + |src, dst, count| core::ptr::copy(src, dst, count), + traph, + ) + .map_err(|_| MemoryAccessReason::Load)?; + + // Store from buffer + self.memory_access( + MemoryAccessReason::Store, + dst, + buf, + count, + |perm| perm == Permission::Write, + |dst, src, count| core::ptr::copy(src, dst, count), + traph, + ) + .map_err(|_| MemoryAccessReason::Store)?; + + Ok::<_, MemoryAccessReason>(()) + })(); + + // Deallocate if used heap-allocated array + if count > STACK_BUFFER_SIZE { + alloc::alloc::dealloc( + buf, + core::alloc::Layout::from_size_align_unchecked(count, 1), + ); } + + status } - #[inline] - pub fn root_pt(&self) -> &PageTable { - unsafe { &*self.root_pt } - } - - #[inline] - pub fn root_pt_mut(&mut self) -> &mut PageTable { - unsafe { &mut *self.root_pt } - } - + /// Split address to pages, check their permissions and feed pointers with offset + /// to a specified function. + /// + /// If page is not found, execute page fault trap handler. + #[allow(clippy::too_many_arguments)] // Silence peasant fn memory_access( - &self, + &mut self, + reason: MemoryAccessReason, src: u64, mut dst: *mut u8, len: usize, - permission_check: impl Fn(Permission) -> bool, - action: impl Fn(*mut u8, *mut u8, usize), + permission_check: fn(Permission) -> bool, + action: fn(*mut u8, *mut u8, usize), + traph: &mut impl HandleTrap, ) -> Result<(), ()> { - for PageSplitResult { ptr, size, perm } in PageSplitter::new(src, len, self.root_pt) { - if !permission_check(perm) { - return Err(()); + let mut pspl = AddrSplitter::new(src, len, self.root_pt); + loop { + match pspl.next() { + // Page found + Some(Ok(AddrSplitOk { ptr, size, perm })) => { + if !permission_check(perm) { + return Err(()); + } + + // Perform memory action and bump dst pointer + action(ptr, dst, size); + dst = unsafe { dst.add(size) }; + } + Some(Err(AddrSplitError { addr, size })) => { + // Execute page fault handler + if traph.page_fault(reason, self, addr, size, dst) { + // Shift the splitter address + pspl.bump(size); + + // Bump dst pointer + dst = unsafe { dst.add(size as _) }; + } else { + return Err(()); // Unhandleable + } + } + None => return Ok(()), } - - action(ptr, dst, size); - dst = unsafe { dst.add(size) }; } - - Ok(()) } } -struct PageSplitResult { +/// Result from address split +struct AddrSplitOk { + /// 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, } -struct PageSplitter { +struct AddrSplitError { + /// Address of failure addr: u64, + + /// Requested page size + size: PageSize, +} + +/// Address splitter into pages +struct AddrSplitter { + /// Current address + addr: u64, + + /// Size left size: usize, + + /// Page table pagetable: *const PageTable, } -impl PageSplitter { +impl AddrSplitter { + /// Create a new page splitter pub const fn new(addr: u64, size: usize, pagetable: *const PageTable) -> Self { Self { addr, @@ -161,19 +274,29 @@ impl PageSplitter { 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 PageSplitter { - type Item = PageSplitResult; +impl Iterator for AddrSplitter { + type Item = Result; fn next(&mut self) -> Option { + // 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).get_unchecked( usize::try_from((self.addr >> (lvl * 9 + 12)) & ((1 << 9) - 1)) @@ -182,34 +305,102 @@ impl Iterator for PageSplitter { let ptr = entry.ptr(); match entry.permission() { - Permission::Empty => return None, + // No page → page fault + Permission::Empty => { + return Some(Err(AddrSplitError { + addr: self.addr, + size: PageSize::from_lvl(lvl)?, + })) + } + + // Node → proceed waking Permission::Node => current_pt = ptr as _, + + // Leaft → return relevant data perm => { break 'a ( + // Pointer in host memory ptr as *mut u8, perm, - match lvl { - 0 => 4096, - 1 => 1024_usize.pow(2) * 2, - 2 => 1024_usize.pow(3), - _ => return None, - }, + PageSize::from_lvl(lvl)?, + // In-page offset self.addr as usize & ((1 << (lvl * 9 + 12)) - 1), - ) + ); } } } } - return None; + return None; // Reached the end (should not happen) }; - let avail = (size - offset).clamp(0, self.size); - self.addr += size as u64; - self.size = self.size.saturating_sub(size); - Some(PageSplitResult { - ptr: unsafe { base.add(offset) }, + // 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(AddrSplitOk { + ptr: unsafe { base.add(offset) }, // Return pointer to the start of region size: avail, perm, - }) + })) + } +} + +/// Page size +#[derive(Clone, Copy, Debug, PartialEq, Eq)] +pub enum PageSize { + /// 4 KiB page (on level 0) + Size4K = 4096, + + /// 2 MiB page (on level 1) + Size2M = 1024 * 1024 * 2, + + /// 1 GiB page (on level 2) + Size1G = 1024 * 1024 * 1024, +} + +impl PageSize { + /// Convert page table level to size of page + fn from_lvl(lvl: u8) -> Option { + match lvl { + 0 => Some(PageSize::Size4K), + 1 => Some(PageSize::Size2M), + 2 => Some(PageSize::Size1G), + _ => None, + } + } +} + +/// Unhandled load access trap +#[derive(Clone, Copy, Display, Debug, PartialEq, Eq)] +pub struct LoadError; + +/// Unhandled store access trap +#[derive(Clone, Copy, Display, Debug, PartialEq, Eq)] +pub struct StoreError; + +#[derive(Clone, Copy, Display, Debug, PartialEq, Eq)] +pub enum MemoryAccessReason { + Load, + Store, +} + +impl From for VmRunError { + fn from(value: MemoryAccessReason) -> Self { + match value { + MemoryAccessReason::Load => Self::LoadAccessEx, + MemoryAccessReason::Store => Self::StoreAccessEx, + } + } +} + +impl From for VmRunError { + fn from(_: LoadError) -> Self { + Self::LoadAccessEx + } +} + +impl From for VmRunError { + fn from(_: StoreError) -> Self { + Self::StoreAccessEx } } diff --git a/hbvm/src/vm/mem/paging.rs b/hbvm/src/vm/mem/paging.rs index ae9c0bf..80dfdcf 100644 --- a/hbvm/src/vm/mem/paging.rs +++ b/hbvm/src/vm/mem/paging.rs @@ -6,30 +6,40 @@ use core::{ }; use delegate::delegate; +/// Page entry permission #[derive(Clone, Copy, Debug, Default, PartialEq, Eq)] #[repr(u8)] pub enum Permission { + /// No page present #[default] Empty, + /// Points to another pagetable Node, + /// Page is read only Readonly, + /// Page is readable and writable Write, + /// Page is readable and executable Exec, } +/// Page table entry #[derive(Clone, Copy, Default, PartialEq, Eq)] pub struct PtEntry(u64); impl PtEntry { + /// Create new #[inline] pub unsafe fn new(ptr: *mut PtPointedData, permission: Permission) -> Self { Self(ptr as u64 | permission as u64) } + /// Get permission #[inline] pub fn permission(&self) -> Permission { unsafe { core::mem::transmute(self.0 as u8 & 0b111) } } + /// Get pointer to the data (leaf) or next page table (node) #[inline] pub fn ptr(&self) -> *mut PtPointedData { (self.0 & !((1 << 12) - 1)) as _ @@ -45,6 +55,8 @@ impl Debug for PtEntry { } } + +/// Page table #[derive(Clone, Copy, Debug, PartialEq, Eq)] #[repr(align(4096))] pub struct PageTable([PtEntry; 512]); @@ -89,13 +101,17 @@ where impl Default for PageTable { fn default() -> Self { + // SAFETY: It's fine, zeroed page table entry is valid (= empty) Self(unsafe { MaybeUninit::zeroed().assume_init() }) } } +/// Data page table entry can possibly point to #[derive(Clone, Copy)] #[repr(C, align(4096))] pub union PtPointedData { + /// Node - next page table pub pt: PageTable, + /// Leaf pub page: u8, } diff --git a/hbvm/src/vm/mod.rs b/hbvm/src/vm/mod.rs index ccb60ef..834e90f 100644 --- a/hbvm/src/vm/mod.rs +++ b/hbvm/src/vm/mod.rs @@ -11,8 +11,11 @@ // program size. If you are (rightfully) worried about the UB, for now just // append your program with 11 zeroes. -mod mem; -mod value; +use self::trap::HandleTrap; + +pub mod mem; +pub mod trap; +pub mod value; use { crate::validate, @@ -23,6 +26,7 @@ use { value::Value, }; +/// Extract a parameter from program macro_rules! param { ($self:expr, $ty:ty) => {{ assert_impl_one!($ty: OpParam); @@ -37,6 +41,7 @@ macro_rules! param { }}; } +/// Perform binary operation `#0 ← #1 OP #2` macro_rules! binary_op { ($self:expr, $ty:ident, $handler:expr) => {{ let ParamBBB(tg, a0, a1) = param!($self, ParamBBB); @@ -51,6 +56,7 @@ macro_rules! binary_op { }}; } +/// Perform binary operation with immediate `#0 ← #1 OP imm #2` macro_rules! binary_op_imm { ($self:expr, $ty:ident, $handler:expr) => {{ let ParamBBD(tg, a0, imm) = param!($self, ParamBBD); @@ -61,6 +67,7 @@ macro_rules! binary_op_imm { }}; } +/// Jump at `#3` if ordering on `#0 <=> #1` is equal to expected macro_rules! cond_jump { ($self:expr, $ty:ident, $expected:ident) => {{ let ParamBBD(a0, a1, jt) = param!($self, ParamBBD); @@ -72,36 +79,59 @@ macro_rules! cond_jump { }}; } -pub struct Vm<'a> { +/// HoleyBytes Virtual Machine +pub struct Vm<'a, T> { + /// Holds 256 registers + /// + /// Writing to register 0 is considered undefined behaviour + /// in terms of HoleyBytes program execution pub registers: [Value; 256], + + /// Memory implementation pub memory: Memory, + + /// Trap handler + pub traph: T, + + // Program counter pc: usize, + + /// Program program: &'a [u8], } -impl<'a> Vm<'a> { +impl<'a, T: HandleTrap> Vm<'a, T> { + /// Create a new VM with program and trap handler + /// /// # Safety /// Program code has to be validated - pub unsafe fn new_unchecked(program: &'a [u8]) -> Self { + pub unsafe fn new_unchecked(program: &'a [u8], traph: T) -> Self { Self { registers: [Value::from(0_u64); 256], memory: Default::default(), + traph, pc: 0, program, } } - pub fn new_validated(program: &'a [u8]) -> Result { + /// Create a new VM with program and trap handler only if it passes validation + pub fn new_validated(program: &'a [u8], traph: T) -> Result { validate::validate(program)?; - Ok(unsafe { Self::new_unchecked(program) }) + Ok(unsafe { Self::new_unchecked(program, traph) }) } - pub fn run(&mut self) -> HaltReason { + /// Execute program + /// + /// Program can return [`VmRunError`] if a trap handling failed + pub fn run(&mut self) -> Result<(), VmRunError> { use hbbytecode::opcode::*; loop { + // Fetch instruction let Some(&opcode) = self.program.get(self.pc) - else { return HaltReason::ProgramEnd }; + else { return Ok(()) }; + // Big match unsafe { match opcode { NOP => param!(self, ()), @@ -196,45 +226,30 @@ impl<'a> Vm<'a> { _ => 0, }; - if self - .memory - .load( - self.read_reg(base).as_u64() + off + n as u64, - self.registers.as_mut_ptr().add(usize::from(dst) + n).cast(), - usize::from(count).saturating_sub(n), - ) - .is_err() - { - return HaltReason::LoadAccessEx; - } + self.memory.load( + self.read_reg(base).as_u64() + off + n as u64, + self.registers.as_mut_ptr().add(usize::from(dst) + n).cast(), + usize::from(count).saturating_sub(n), + &mut self.traph, + )?; } ST => { let ParamBBDH(dst, base, off, count) = param!(self, ParamBBDH); - if self - .memory - .store( - self.read_reg(base).as_u64() + off, - self.registers.as_ptr().add(usize::from(dst)).cast(), - count.into(), - ) - .is_err() - { - return HaltReason::LoadAccessEx; - } + self.memory.store( + self.read_reg(base).as_u64() + off, + self.registers.as_ptr().add(usize::from(dst)).cast(), + count.into(), + &mut self.traph, + )?; } BMC => { let ParamBBD(src, dst, count) = param!(self, ParamBBD); - if self - .memory - .block_copy( - self.read_reg(src).as_u64(), - self.read_reg(dst).as_u64(), - count, - ) - .is_err() - { - return HaltReason::LoadAccessEx; - } + self.memory.block_copy( + self.read_reg(src).as_u64(), + self.read_reg(dst).as_u64(), + count as _, + &mut self.traph, + )?; } BRC => { let ParamBBB(src, dst, count) = param!(self, ParamBBB); @@ -261,7 +276,8 @@ impl<'a> Vm<'a> { JGTU => cond_jump!(self, sint, Greater), ECALL => { param!(self, ()); - return HaltReason::Ecall; + self.traph + .ecall(&mut self.registers, &mut self.pc, &mut self.memory); } ADDF => binary_op!(self, as_f64, ops::Add::add), MULF => binary_op!(self, as_f64, ops::Mul::mul), @@ -274,21 +290,29 @@ impl<'a> Vm<'a> { } ADDFI => binary_op_imm!(self, as_f64, ops::Add::add), MULFI => binary_op_imm!(self, as_f64, ops::Mul::mul), - _ => return HaltReason::InvalidOpcode, + op => { + if !self.traph.invalid_op( + &mut self.registers, + &mut self.pc, + &mut self.memory, + op, + ) { + return Err(VmRunError::InvalidOpcodeEx); + } + } } } } } + /// Read register #[inline] unsafe fn read_reg(&self, n: u8) -> Value { - if n == 0 { - 0_u64.into() - } else { - *self.registers.get_unchecked(n as usize) - } + *self.registers.get_unchecked(n as usize) } + /// Write a register. + /// Writing to register 0 is no-op. #[inline] unsafe fn write_reg(&mut self, n: u8, value: Value) { if n != 0 { @@ -297,12 +321,16 @@ impl<'a> Vm<'a> { } } +/// Virtual machine halt error #[derive(Copy, Clone, Debug, PartialEq, Eq)] #[repr(u8)] -pub enum HaltReason { - ProgramEnd, - Ecall, - InvalidOpcode, +pub enum VmRunError { + /// Unhandled invalid opcode exceptions + InvalidOpcodeEx, + + /// Unhandled load access exception LoadAccessEx, + + /// Unhandled store access exception StoreAccessEx, } diff --git a/hbvm/src/vm/trap.rs b/hbvm/src/vm/trap.rs new file mode 100644 index 0000000..f297ab8 --- /dev/null +++ b/hbvm/src/vm/trap.rs @@ -0,0 +1,33 @@ +use super::{ + mem::{Memory, MemoryAccessReason, PageSize}, + value::Value, +}; + +/// Handle VM traps +pub trait HandleTrap { + /// Handle page fault + fn page_fault( + &mut self, + reason: MemoryAccessReason, + memory: &mut Memory, + vaddr: u64, + size: PageSize, + dataptr: *mut u8, + ) -> bool; + + /// Handle invalid opcode exception + fn invalid_op( + &mut self, + regs: &mut [Value; 256], + pc: &mut usize, + memory: &mut Memory, + op: u8, + ) -> bool + where + Self: Sized; + + /// Handle environment calls + fn ecall(&mut self, regs: &mut [Value; 256], pc: &mut usize, memory: &mut Memory) + where + Self: Sized; +} diff --git a/hbvm/src/vm/value.rs b/hbvm/src/vm/value.rs index cfb7300..d573825 100644 --- a/hbvm/src/vm/value.rs +++ b/hbvm/src/vm/value.rs @@ -1,7 +1,13 @@ use core::fmt::Debug; +/// Define [`Value`] union +/// +/// # Safety +/// Union variants have to be sound to byte-reinterpretate +/// between each other. Otherwise the behaviour is undefined. macro_rules! value_def { ($($ty:ident),* $(,)?) => { + /// HBVM register value #[derive(Copy, Clone)] #[repr(packed)] pub union Value { @@ -10,6 +16,7 @@ macro_rules! value_def { paste::paste! { impl Value {$( + #[doc = "Byte-reinterpret [`Value`] as [`" $ty "`]"] #[inline] pub fn [](&self) -> $ty { unsafe { self.$ty } @@ -29,9 +36,11 @@ macro_rules! value_def { } value_def!(u64, i64, f64); +static_assertions::const_assert_eq!(core::mem::size_of::(), 8); impl Debug for Value { fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result { - self.as_u64().fmt(f) + // Print formatted as hexadecimal, unsigned integer + write!(f, "{:x}", self.as_u64()) } }