389 lines
13 KiB
Rust
389 lines
13 KiB
Rust
use std::rc::Rc;
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use std::borrow::Cow;
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use std::collections::HashMap;
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use std::cell::RefCell;
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use rand::rngs::StdRng;
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use syntax::attr;
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use syntax::symbol::sym;
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use rustc::hir::def_id::DefId;
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use rustc::ty::{self, layout::{Size, LayoutOf}, query::TyCtxtAt};
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use rustc::mir;
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use crate::*;
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// Some global facts about the emulated machine.
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pub const PAGE_SIZE: u64 = 4*1024; // FIXME: adjust to target architecture
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pub const STACK_ADDR: u64 = 16*PAGE_SIZE; // not really about the "stack", but where we start assigning integer addresses to allocations
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pub const NUM_CPUS: u64 = 1;
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/// Extra memory kinds
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#[derive(Debug, Copy, Clone, PartialEq, Eq)]
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pub enum MiriMemoryKind {
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/// `__rust_alloc` memory.
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Rust,
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/// `malloc` memory.
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C,
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/// Part of env var emulation.
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Env,
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/// Statics.
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Static,
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}
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impl Into<MemoryKind<MiriMemoryKind>> for MiriMemoryKind {
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#[inline(always)]
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fn into(self) -> MemoryKind<MiriMemoryKind> {
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MemoryKind::Machine(self)
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}
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}
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/// Extra per-allocation data
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#[derive(Debug, Clone)]
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pub struct AllocExtra {
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pub stacked_borrows: stacked_borrows::AllocExtra,
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}
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/// Extra global memory data
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#[derive(Default, Clone, Debug)]
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pub struct MemoryExtra {
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pub stacked_borrows: stacked_borrows::MemoryExtra,
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pub intptrcast: intptrcast::MemoryExtra,
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/// The random number generator to use if Miri is running in non-deterministic mode and to
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/// enable intptrcast
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pub(crate) rng: Option<RefCell<StdRng>>
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}
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impl MemoryExtra {
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pub fn with_rng(rng: Option<StdRng>) -> Self {
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MemoryExtra {
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stacked_borrows: Default::default(),
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intptrcast: Default::default(),
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rng: rng.map(RefCell::new),
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}
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}
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}
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/// The machine itself.
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pub struct Evaluator<'tcx> {
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/// Environment variables set by `setenv`.
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/// Miri does not expose env vars from the host to the emulated program.
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pub(crate) env_vars: HashMap<Vec<u8>, Pointer<Tag>>,
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/// Program arguments (`Option` because we can only initialize them after creating the ecx).
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/// These are *pointers* to argc/argv because macOS.
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/// We also need the full command line as one string because of Windows.
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pub(crate) argc: Option<Pointer<Tag>>,
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pub(crate) argv: Option<Pointer<Tag>>,
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pub(crate) cmd_line: Option<Pointer<Tag>>,
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/// Last OS error.
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pub(crate) last_error: u32,
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/// TLS state.
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pub(crate) tls: TlsData<'tcx>,
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/// Whether to enforce the validity invariant.
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pub(crate) validate: bool,
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}
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impl<'tcx> Evaluator<'tcx> {
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pub(crate) fn new(validate: bool) -> Self {
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Evaluator {
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env_vars: HashMap::default(),
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argc: None,
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argv: None,
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cmd_line: None,
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last_error: 0,
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tls: TlsData::default(),
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validate,
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}
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}
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}
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/// A rustc InterpretCx for Miri.
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pub type MiriEvalContext<'mir, 'tcx> = InterpretCx<'mir, 'tcx, Evaluator<'tcx>>;
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/// A little trait that's useful to be inherited by extension traits.
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pub trait MiriEvalContextExt<'mir, 'tcx> {
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fn eval_context_ref(&self) -> &MiriEvalContext<'mir, 'tcx>;
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fn eval_context_mut(&mut self) -> &mut MiriEvalContext<'mir, 'tcx>;
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}
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impl<'mir, 'tcx> MiriEvalContextExt<'mir, 'tcx> for MiriEvalContext<'mir, 'tcx> {
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#[inline(always)]
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fn eval_context_ref(&self) -> &MiriEvalContext<'mir, 'tcx> {
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self
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}
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#[inline(always)]
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fn eval_context_mut(&mut self) -> &mut MiriEvalContext<'mir, 'tcx> {
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self
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}
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}
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/// Machine hook implementations.
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impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'tcx> {
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type MemoryKinds = MiriMemoryKind;
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type FrameExtra = stacked_borrows::CallId;
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type MemoryExtra = MemoryExtra;
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type AllocExtra = AllocExtra;
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type PointerTag = Tag;
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type MemoryMap = MonoHashMap<AllocId, (MemoryKind<MiriMemoryKind>, Allocation<Tag, Self::AllocExtra>)>;
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const STATIC_KIND: Option<MiriMemoryKind> = Some(MiriMemoryKind::Static);
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#[inline(always)]
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fn enforce_validity(ecx: &InterpretCx<'mir, 'tcx, Self>) -> bool {
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ecx.machine.validate
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}
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/// Returns `Ok()` when the function was handled; fail otherwise.
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#[inline(always)]
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fn find_fn(
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ecx: &mut InterpretCx<'mir, 'tcx, Self>,
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instance: ty::Instance<'tcx>,
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args: &[OpTy<'tcx, Tag>],
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dest: Option<PlaceTy<'tcx, Tag>>,
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ret: Option<mir::BasicBlock>,
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) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
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ecx.find_fn(instance, args, dest, ret)
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}
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#[inline(always)]
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fn call_intrinsic(
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ecx: &mut rustc_mir::interpret::InterpretCx<'mir, 'tcx, Self>,
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instance: ty::Instance<'tcx>,
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args: &[OpTy<'tcx, Tag>],
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dest: PlaceTy<'tcx, Tag>,
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) -> InterpResult<'tcx> {
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ecx.call_intrinsic(instance, args, dest)
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}
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#[inline(always)]
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fn ptr_op(
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ecx: &rustc_mir::interpret::InterpretCx<'mir, 'tcx, Self>,
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bin_op: mir::BinOp,
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left: ImmTy<'tcx, Tag>,
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right: ImmTy<'tcx, Tag>,
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) -> InterpResult<'tcx, (Scalar<Tag>, bool)> {
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ecx.ptr_op(bin_op, left, right)
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}
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fn box_alloc(
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ecx: &mut InterpretCx<'mir, 'tcx, Self>,
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dest: PlaceTy<'tcx, Tag>,
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) -> InterpResult<'tcx> {
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trace!("box_alloc for {:?}", dest.layout.ty);
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// Call the `exchange_malloc` lang item.
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let malloc = ecx.tcx.lang_items().exchange_malloc_fn().unwrap();
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let malloc = ty::Instance::mono(ecx.tcx.tcx, malloc);
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let malloc_mir = ecx.load_mir(malloc.def)?;
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ecx.push_stack_frame(
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malloc,
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malloc_mir.span,
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malloc_mir,
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Some(dest),
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// Don't do anything when we are done. The `statement()` function will increment
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// the old stack frame's stmt counter to the next statement, which means that when
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// `exchange_malloc` returns, we go on evaluating exactly where we want to be.
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StackPopCleanup::None { cleanup: true },
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)?;
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let mut args = ecx.frame().body.args_iter();
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let layout = ecx.layout_of(dest.layout.ty.builtin_deref(false).unwrap().ty)?;
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// First argument: `size`.
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// (`0` is allowed here -- this is expected to be handled by the lang item).
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let arg = ecx.eval_place(&mir::Place::Base(mir::PlaceBase::Local(args.next().unwrap())))?;
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let size = layout.size.bytes();
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ecx.write_scalar(Scalar::from_uint(size, arg.layout.size), arg)?;
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// Second argument: `align`.
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let arg = ecx.eval_place(&mir::Place::Base(mir::PlaceBase::Local(args.next().unwrap())))?;
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let align = layout.align.abi.bytes();
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ecx.write_scalar(Scalar::from_uint(align, arg.layout.size), arg)?;
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// No more arguments.
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assert!(
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args.next().is_none(),
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"`exchange_malloc` lang item has more arguments than expected"
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);
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Ok(())
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}
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fn find_foreign_static(
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def_id: DefId,
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tcx: TyCtxtAt<'tcx>,
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) -> InterpResult<'tcx, Cow<'tcx, Allocation>> {
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let attrs = tcx.get_attrs(def_id);
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let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
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Some(name) => name.as_str(),
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None => tcx.item_name(def_id).as_str(),
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};
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let alloc = match link_name.get() {
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"__cxa_thread_atexit_impl" => {
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// This should be all-zero, pointer-sized.
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let size = tcx.data_layout.pointer_size;
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let data = vec![0; size.bytes() as usize];
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Allocation::from_bytes(&data, tcx.data_layout.pointer_align.abi)
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}
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_ => return err!(Unimplemented(
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format!("can't access foreign static: {}", link_name),
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)),
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};
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Ok(Cow::Owned(alloc))
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}
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#[inline(always)]
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fn before_terminator(_ecx: &mut InterpretCx<'mir, 'tcx, Self>) -> InterpResult<'tcx>
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{
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// We are not interested in detecting loops.
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Ok(())
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}
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fn tag_allocation<'b>(
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id: AllocId,
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alloc: Cow<'b, Allocation>,
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kind: Option<MemoryKind<Self::MemoryKinds>>,
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memory: &Memory<'mir, 'tcx, Self>,
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) -> (Cow<'b, Allocation<Self::PointerTag, Self::AllocExtra>>, Self::PointerTag) {
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let kind = kind.expect("we set our STATIC_KIND so this cannot be None");
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let alloc = alloc.into_owned();
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let (stacks, base_tag) = Stacks::new_allocation(
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id,
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Size::from_bytes(alloc.bytes.len() as u64),
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Rc::clone(&memory.extra.stacked_borrows),
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kind,
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);
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if kind != MiriMemoryKind::Static.into() {
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assert!(alloc.relocations.is_empty(), "Only statics can come initialized with inner pointers");
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// Now we can rely on the inner pointers being static, too.
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}
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let mut memory_extra = memory.extra.stacked_borrows.borrow_mut();
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let alloc: Allocation<Tag, Self::AllocExtra> = Allocation {
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bytes: alloc.bytes,
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relocations: Relocations::from_presorted(
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alloc.relocations.iter()
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// The allocations in the relocations (pointers stored *inside* this allocation)
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// all get the base pointer tag.
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.map(|&(offset, ((), alloc))| (offset, (memory_extra.static_base_ptr(alloc), alloc)))
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.collect()
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),
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undef_mask: alloc.undef_mask,
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align: alloc.align,
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mutability: alloc.mutability,
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extra: AllocExtra {
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stacked_borrows: stacks,
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},
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};
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(Cow::Owned(alloc), base_tag)
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}
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#[inline(always)]
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fn tag_static_base_pointer(
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id: AllocId,
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memory: &Memory<'mir, 'tcx, Self>,
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) -> Self::PointerTag {
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memory.extra.stacked_borrows.borrow_mut().static_base_ptr(id)
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}
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#[inline(always)]
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fn retag(
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ecx: &mut InterpretCx<'mir, 'tcx, Self>,
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kind: mir::RetagKind,
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place: PlaceTy<'tcx, Tag>,
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) -> InterpResult<'tcx> {
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if !ecx.tcx.sess.opts.debugging_opts.mir_emit_retag || !Self::enforce_validity(ecx) {
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// No tracking, or no retagging. The latter is possible because a dependency of ours
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// might be called with different flags than we are, so there are `Retag`
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// statements but we do not want to execute them.
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// Also, honor the whitelist in `enforce_validity` because otherwise we might retag
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// uninitialized data.
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Ok(())
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} else {
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ecx.retag(kind, place)
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}
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}
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#[inline(always)]
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fn stack_push(
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ecx: &mut InterpretCx<'mir, 'tcx, Self>,
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) -> InterpResult<'tcx, stacked_borrows::CallId> {
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Ok(ecx.memory().extra.stacked_borrows.borrow_mut().new_call())
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}
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#[inline(always)]
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fn stack_pop(
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ecx: &mut InterpretCx<'mir, 'tcx, Self>,
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extra: stacked_borrows::CallId,
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) -> InterpResult<'tcx> {
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Ok(ecx.memory().extra.stacked_borrows.borrow_mut().end_call(extra))
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}
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fn int_to_ptr(
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int: u64,
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memory: &Memory<'mir, 'tcx, Self>,
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) -> InterpResult<'tcx, Pointer<Self::PointerTag>> {
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if int == 0 {
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err!(InvalidNullPointerUsage)
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} else if memory.extra.rng.is_none() {
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err!(ReadBytesAsPointer)
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} else {
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intptrcast::GlobalState::int_to_ptr(int, memory)
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}
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}
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fn ptr_to_int(
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ptr: Pointer<Self::PointerTag>,
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memory: &Memory<'mir, 'tcx, Self>,
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) -> InterpResult<'tcx, u64> {
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if memory.extra.rng.is_none() {
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err!(ReadPointerAsBytes)
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} else {
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intptrcast::GlobalState::ptr_to_int(ptr, memory)
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}
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}
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}
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impl AllocationExtra<Tag> for AllocExtra {
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#[inline(always)]
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fn memory_read<'tcx>(
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alloc: &Allocation<Tag, AllocExtra>,
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ptr: Pointer<Tag>,
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size: Size,
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) -> InterpResult<'tcx> {
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alloc.extra.stacked_borrows.memory_read(ptr, size)
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}
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#[inline(always)]
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fn memory_written<'tcx>(
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alloc: &mut Allocation<Tag, AllocExtra>,
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ptr: Pointer<Tag>,
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size: Size,
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) -> InterpResult<'tcx> {
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alloc.extra.stacked_borrows.memory_written(ptr, size)
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}
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#[inline(always)]
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fn memory_deallocated<'tcx>(
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alloc: &mut Allocation<Tag, AllocExtra>,
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ptr: Pointer<Tag>,
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size: Size,
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) -> InterpResult<'tcx> {
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alloc.extra.stacked_borrows.memory_deallocated(ptr, size)
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}
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}
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impl MayLeak for MiriMemoryKind {
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#[inline(always)]
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fn may_leak(self) -> bool {
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use self::MiriMemoryKind::*;
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match self {
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Rust | C => false,
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Env | Static => true,
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}
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}
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}
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