rust/src/machine.rs

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//! Global machine state as well as implementation of the interpreter engine
//! `Machine` trait.
use std::rc::Rc;
use std::borrow::Cow;
use std::collections::HashMap;
use std::cell::RefCell;
use rand::rngs::StdRng;
use syntax::attr;
use syntax::symbol::sym;
use rustc::hir::def_id::DefId;
use rustc::ty::{self, layout::{Size, LayoutOf}, TyCtxt};
use rustc::mir;
use crate::*;
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// Some global facts about the emulated machine.
pub const PAGE_SIZE: u64 = 4*1024; // FIXME: adjust to target architecture
pub const STACK_ADDR: u64 = 32*PAGE_SIZE; // not really about the "stack", but where we start assigning integer addresses to allocations
pub const STACK_SIZE: u64 = 16*PAGE_SIZE; // whatever
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pub const NUM_CPUS: u64 = 1;
/// Extra memory kinds
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum MiriMemoryKind {
/// `__rust_alloc` memory.
Rust,
/// `malloc` memory.
C,
/// Windows `HeapAlloc` memory.
WinHeap,
/// Part of env var emulation.
Env,
/// Statics.
Static,
}
impl Into<MemoryKind<MiriMemoryKind>> for MiriMemoryKind {
#[inline(always)]
fn into(self) -> MemoryKind<MiriMemoryKind> {
MemoryKind::Machine(self)
}
}
/// Extra per-allocation data
#[derive(Debug, Clone)]
pub struct AllocExtra {
/// Stacked Borrows state is only added if validation is enabled.
pub stacked_borrows: Option<stacked_borrows::AllocExtra>,
}
/// Extra global memory data
#[derive(Clone, Debug)]
pub struct MemoryExtra {
pub stacked_borrows: stacked_borrows::MemoryExtra,
pub intptrcast: intptrcast::MemoryExtra,
/// The random number generator to use if Miri is running in non-deterministic mode and to
/// enable intptrcast
pub(crate) rng: Option<RefCell<StdRng>>,
/// Whether to enforce the validity invariant.
pub(crate) validate: bool,
}
impl MemoryExtra {
pub fn new(rng: Option<StdRng>, validate: bool) -> Self {
MemoryExtra {
stacked_borrows: Default::default(),
intptrcast: Default::default(),
rng: rng.map(RefCell::new),
validate,
}
}
}
/// The machine itself.
pub struct Evaluator<'tcx> {
/// Environment variables set by `setenv`.
/// Miri does not expose env vars from the host to the emulated program.
pub(crate) env_vars: HashMap<Vec<u8>, Pointer<Tag>>,
/// Program arguments (`Option` because we can only initialize them after creating the ecx).
/// These are *pointers* to argc/argv because macOS.
/// We also need the full command line as one string because of Windows.
pub(crate) argc: Option<Pointer<Tag>>,
pub(crate) argv: Option<Pointer<Tag>>,
pub(crate) cmd_line: Option<Pointer<Tag>>,
/// Last OS error.
pub(crate) last_error: u32,
/// TLS state.
pub(crate) tls: TlsData<'tcx>,
}
impl<'tcx> Evaluator<'tcx> {
pub(crate) fn new() -> Self {
Evaluator {
env_vars: HashMap::default(),
argc: None,
argv: None,
cmd_line: None,
last_error: 0,
tls: TlsData::default(),
}
}
}
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/// A rustc InterpCx for Miri.
pub type MiriEvalContext<'mir, 'tcx> = InterpCx<'mir, 'tcx, Evaluator<'tcx>>;
/// A little trait that's useful to be inherited by extension traits.
pub trait MiriEvalContextExt<'mir, 'tcx> {
fn eval_context_ref(&self) -> &MiriEvalContext<'mir, 'tcx>;
fn eval_context_mut(&mut self) -> &mut MiriEvalContext<'mir, 'tcx>;
}
impl<'mir, 'tcx> MiriEvalContextExt<'mir, 'tcx> for MiriEvalContext<'mir, 'tcx> {
#[inline(always)]
fn eval_context_ref(&self) -> &MiriEvalContext<'mir, 'tcx> {
self
}
#[inline(always)]
fn eval_context_mut(&mut self) -> &mut MiriEvalContext<'mir, 'tcx> {
self
}
}
/// Machine hook implementations.
impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'tcx> {
type MemoryKinds = MiriMemoryKind;
type FrameExtra = stacked_borrows::CallId;
type MemoryExtra = MemoryExtra;
type AllocExtra = AllocExtra;
type PointerTag = Tag;
type ExtraFnVal = Dlsym;
type MemoryMap = MonoHashMap<AllocId, (MemoryKind<MiriMemoryKind>, Allocation<Tag, Self::AllocExtra>)>;
const STATIC_KIND: Option<MiriMemoryKind> = Some(MiriMemoryKind::Static);
#[inline(always)]
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fn enforce_validity(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool {
ecx.memory().extra.validate
}
#[inline(always)]
fn find_fn(
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ecx: &mut InterpCx<'mir, 'tcx, Self>,
instance: ty::Instance<'tcx>,
args: &[OpTy<'tcx, Tag>],
dest: Option<PlaceTy<'tcx, Tag>>,
ret: Option<mir::BasicBlock>,
) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
ecx.find_fn(instance, args, dest, ret)
}
#[inline(always)]
fn call_extra_fn(
ecx: &mut InterpCx<'mir, 'tcx, Self>,
fn_val: Dlsym,
args: &[OpTy<'tcx, Tag>],
dest: Option<PlaceTy<'tcx, Tag>>,
ret: Option<mir::BasicBlock>,
) -> InterpResult<'tcx> {
ecx.call_dlsym(fn_val, args, dest, ret)
}
#[inline(always)]
fn call_intrinsic(
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ecx: &mut rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
instance: ty::Instance<'tcx>,
args: &[OpTy<'tcx, Tag>],
dest: PlaceTy<'tcx, Tag>,
) -> InterpResult<'tcx> {
ecx.call_intrinsic(instance, args, dest)
}
#[inline(always)]
fn ptr_op(
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ecx: &rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
bin_op: mir::BinOp,
left: ImmTy<'tcx, Tag>,
right: ImmTy<'tcx, Tag>,
) -> InterpResult<'tcx, (Scalar<Tag>, bool)> {
ecx.ptr_op(bin_op, left, right)
}
fn box_alloc(
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ecx: &mut InterpCx<'mir, 'tcx, Self>,
dest: PlaceTy<'tcx, Tag>,
) -> InterpResult<'tcx> {
trace!("box_alloc for {:?}", dest.layout.ty);
// Call the `exchange_malloc` lang item.
let malloc = ecx.tcx.lang_items().exchange_malloc_fn().unwrap();
let malloc = ty::Instance::mono(ecx.tcx.tcx, malloc);
let malloc_mir = ecx.load_mir(malloc.def)?;
ecx.push_stack_frame(
malloc,
malloc_mir.span,
malloc_mir,
Some(dest),
// Don't do anything when we are done. The `statement()` function will increment
// the old stack frame's stmt counter to the next statement, which means that when
// `exchange_malloc` returns, we go on evaluating exactly where we want to be.
StackPopCleanup::None { cleanup: true },
)?;
let mut args = ecx.frame().body.args_iter();
let layout = ecx.layout_of(dest.layout.ty.builtin_deref(false).unwrap().ty)?;
// First argument: `size`.
// (`0` is allowed here -- this is expected to be handled by the lang item).
let arg = ecx.eval_place(&mir::Place::Base(mir::PlaceBase::Local(args.next().unwrap())))?;
let size = layout.size.bytes();
ecx.write_scalar(Scalar::from_uint(size, arg.layout.size), arg)?;
// Second argument: `align`.
let arg = ecx.eval_place(&mir::Place::Base(mir::PlaceBase::Local(args.next().unwrap())))?;
let align = layout.align.abi.bytes();
ecx.write_scalar(Scalar::from_uint(align, arg.layout.size), arg)?;
// No more arguments.
assert!(
args.next().is_none(),
"`exchange_malloc` lang item has more arguments than expected"
);
Ok(())
}
fn find_foreign_static(
tcx: TyCtxt<'tcx>,
def_id: DefId,
) -> InterpResult<'tcx, Cow<'tcx, Allocation>> {
let attrs = tcx.get_attrs(def_id);
let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
Some(name) => name.as_str(),
None => tcx.item_name(def_id).as_str(),
};
let alloc = match link_name.get() {
"__cxa_thread_atexit_impl" => {
// This should be all-zero, pointer-sized.
let size = tcx.data_layout.pointer_size;
let data = vec![0; size.bytes() as usize];
Allocation::from_bytes(&data, tcx.data_layout.pointer_align.abi)
}
_ => return err!(Unimplemented(
format!("can't access foreign static: {}", link_name),
)),
};
Ok(Cow::Owned(alloc))
}
#[inline(always)]
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fn before_terminator(_ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx>
{
// We are not interested in detecting loops.
Ok(())
}
fn tag_allocation<'b>(
memory_extra: &MemoryExtra,
id: AllocId,
alloc: Cow<'b, Allocation>,
kind: Option<MemoryKind<Self::MemoryKinds>>,
) -> (Cow<'b, Allocation<Self::PointerTag, Self::AllocExtra>>, Self::PointerTag) {
let kind = kind.expect("we set our STATIC_KIND so this cannot be None");
let alloc = alloc.into_owned();
let (stacks, base_tag) = if !memory_extra.validate {
(None, Tag::Untagged)
} else {
let (stacks, base_tag) = Stacks::new_allocation(
id,
Size::from_bytes(alloc.bytes.len() as u64),
Rc::clone(&memory_extra.stacked_borrows),
kind,
);
(Some(stacks), base_tag)
};
if kind != MiriMemoryKind::Static.into() {
assert!(alloc.relocations.is_empty(), "Only statics can come initialized with inner pointers");
// Now we can rely on the inner pointers being static, too.
}
let mut stacked_borrows = memory_extra.stacked_borrows.borrow_mut();
let alloc: Allocation<Tag, Self::AllocExtra> = Allocation {
bytes: alloc.bytes,
relocations: Relocations::from_presorted(
alloc.relocations.iter()
// The allocations in the relocations (pointers stored *inside* this allocation)
// all get the base pointer tag.
.map(|&(offset, ((), alloc))| {
let tag = if !memory_extra.validate {
Tag::Untagged
} else {
stacked_borrows.static_base_ptr(alloc)
};
(offset, (tag, alloc))
})
.collect()
),
undef_mask: alloc.undef_mask,
align: alloc.align,
mutability: alloc.mutability,
extra: AllocExtra {
stacked_borrows: stacks,
},
};
(Cow::Owned(alloc), base_tag)
}
#[inline(always)]
fn tag_static_base_pointer(
memory_extra: &MemoryExtra,
id: AllocId,
) -> Self::PointerTag {
if !memory_extra.validate {
Tag::Untagged
} else {
memory_extra.stacked_borrows.borrow_mut().static_base_ptr(id)
}
}
#[inline(always)]
fn retag(
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ecx: &mut InterpCx<'mir, 'tcx, Self>,
kind: mir::RetagKind,
place: PlaceTy<'tcx, Tag>,
) -> InterpResult<'tcx> {
if !Self::enforce_validity(ecx) {
// No tracking.
Ok(())
} else {
ecx.retag(kind, place)
}
}
#[inline(always)]
fn stack_push(
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ecx: &mut InterpCx<'mir, 'tcx, Self>,
) -> InterpResult<'tcx, stacked_borrows::CallId> {
Ok(ecx.memory().extra.stacked_borrows.borrow_mut().new_call())
}
#[inline(always)]
fn stack_pop(
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ecx: &mut InterpCx<'mir, 'tcx, Self>,
extra: stacked_borrows::CallId,
) -> InterpResult<'tcx> {
Ok(ecx.memory().extra.stacked_borrows.borrow_mut().end_call(extra))
}
fn int_to_ptr(
memory: &Memory<'mir, 'tcx, Self>,
int: u64,
) -> InterpResult<'tcx, Pointer<Self::PointerTag>> {
if int == 0 {
err!(InvalidNullPointerUsage)
} else if memory.extra.rng.is_none() {
err!(ReadBytesAsPointer)
} else {
intptrcast::GlobalState::int_to_ptr(int, memory)
}
}
fn ptr_to_int(
memory: &Memory<'mir, 'tcx, Self>,
ptr: Pointer<Self::PointerTag>,
) -> InterpResult<'tcx, u64> {
if memory.extra.rng.is_none() {
err!(ReadPointerAsBytes)
} else {
intptrcast::GlobalState::ptr_to_int(ptr, memory)
}
}
}
impl AllocationExtra<Tag> for AllocExtra {
#[inline(always)]
fn memory_read<'tcx>(
alloc: &Allocation<Tag, AllocExtra>,
ptr: Pointer<Tag>,
size: Size,
) -> InterpResult<'tcx> {
if let Some(ref stacked_borrows) = alloc.extra.stacked_borrows {
stacked_borrows.memory_read(ptr, size)
} else {
Ok(())
}
}
#[inline(always)]
fn memory_written<'tcx>(
alloc: &mut Allocation<Tag, AllocExtra>,
ptr: Pointer<Tag>,
size: Size,
) -> InterpResult<'tcx> {
if let Some(ref mut stacked_borrows) = alloc.extra.stacked_borrows {
stacked_borrows.memory_written(ptr, size)
} else {
Ok(())
}
}
#[inline(always)]
fn memory_deallocated<'tcx>(
alloc: &mut Allocation<Tag, AllocExtra>,
ptr: Pointer<Tag>,
size: Size,
) -> InterpResult<'tcx> {
if let Some(ref mut stacked_borrows) = alloc.extra.stacked_borrows {
stacked_borrows.memory_deallocated(ptr, size)
} else {
Ok(())
}
}
}
impl MayLeak for MiriMemoryKind {
#[inline(always)]
fn may_leak(self) -> bool {
use self::MiriMemoryKind::*;
match self {
Rust | C | WinHeap => false,
Env | Static => true,
}
}
}