1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604
//! Main evaluator loop and setting up the initial stack frame.
use std::ffi::{OsStr, OsString};
use std::iter;
use std::panic::{self, AssertUnwindSafe};
use std::path::PathBuf;
use std::task::Poll;
use std::thread;
use crate::concurrency::thread::TlsAllocAction;
use crate::diagnostics::report_leaks;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_hir::def::Namespace;
use rustc_hir::def_id::DefId;
use rustc_middle::ty::{
self,
layout::{LayoutCx, LayoutOf},
Ty, TyCtxt,
};
use rustc_target::spec::abi::Abi;
use rustc_session::config::EntryFnType;
use crate::shims::tls;
use crate::*;
/// When the main thread would exit, we will yield to any other thread that is ready to execute.
/// But we must only do that a finite number of times, or a background thread running `loop {}`
/// will hang the program.
const MAIN_THREAD_YIELDS_AT_SHUTDOWN: u32 = 256;
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum AlignmentCheck {
/// Do not check alignment.
None,
/// Check alignment "symbolically", i.e., using only the requested alignment for an allocation and not its real base address.
Symbolic,
/// Check alignment on the actual physical integer address.
Int,
}
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum RejectOpWith {
/// Isolated op is rejected with an abort of the machine.
Abort,
/// If not Abort, miri returns an error for an isolated op.
/// Following options determine if user should be warned about such error.
/// Do not print warning about rejected isolated op.
NoWarning,
/// Print a warning about rejected isolated op, with backtrace.
Warning,
/// Print a warning about rejected isolated op, without backtrace.
WarningWithoutBacktrace,
}
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum IsolatedOp {
/// Reject an op requiring communication with the host. By
/// default, miri rejects the op with an abort. If not, it returns
/// an error code, and prints a warning about it. Warning levels
/// are controlled by `RejectOpWith` enum.
Reject(RejectOpWith),
/// Execute op requiring communication with the host, i.e. disable isolation.
Allow,
}
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum BacktraceStyle {
/// Prints a terser backtrace which ideally only contains relevant information.
Short,
/// Prints a backtrace with all possible information.
Full,
/// Prints only the frame that the error occurs in.
Off,
}
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum ValidationMode {
/// Do not perform any kind of validation.
No,
/// Validate the interior of the value, but not things behind references.
Shallow,
/// Fully recursively validate references.
Deep,
}
/// Configuration needed to spawn a Miri instance.
#[derive(Clone)]
pub struct MiriConfig {
/// The host environment snapshot to use as basis for what is provided to the interpreted program.
/// (This is still subject to isolation as well as `forwarded_env_vars`.)
pub env: Vec<(OsString, OsString)>,
/// Determine if validity checking is enabled.
pub validation: ValidationMode,
/// Determines if Stacked Borrows or Tree Borrows is enabled.
pub borrow_tracker: Option<BorrowTrackerMethod>,
/// Whether `core::ptr::Unique` receives special treatment.
/// If `true` then `Unique` is reborrowed with its own new tag and permission,
/// otherwise `Unique` is just another raw pointer.
pub unique_is_unique: bool,
/// Controls alignment checking.
pub check_alignment: AlignmentCheck,
/// Action for an op requiring communication with the host.
pub isolated_op: IsolatedOp,
/// Determines if memory leaks should be ignored.
pub ignore_leaks: bool,
/// Environment variables that should always be forwarded from the host.
pub forwarded_env_vars: Vec<String>,
/// Additional environment variables that should be set in the interpreted program.
pub set_env_vars: FxHashMap<String, String>,
/// Command-line arguments passed to the interpreted program.
pub args: Vec<String>,
/// The seed to use when non-determinism or randomness are required (e.g. ptr-to-int cast, `getrandom()`).
pub seed: Option<u64>,
/// The stacked borrows pointer ids to report about
pub tracked_pointer_tags: FxHashSet<BorTag>,
/// The allocation ids to report about.
pub tracked_alloc_ids: FxHashSet<AllocId>,
/// For the tracked alloc ids, also report read/write accesses.
pub track_alloc_accesses: bool,
/// Determine if data race detection should be enabled
pub data_race_detector: bool,
/// Determine if weak memory emulation should be enabled. Requires data race detection to be enabled
pub weak_memory_emulation: bool,
/// Track when an outdated (weak memory) load happens.
pub track_outdated_loads: bool,
/// Rate of spurious failures for compare_exchange_weak atomic operations,
/// between 0.0 and 1.0, defaulting to 0.8 (80% chance of failure).
pub cmpxchg_weak_failure_rate: f64,
/// If `Some`, enable the `measureme` profiler, writing results to a file
/// with the specified prefix.
pub measureme_out: Option<String>,
/// Panic when unsupported functionality is encountered.
pub panic_on_unsupported: bool,
/// Which style to use for printing backtraces.
pub backtrace_style: BacktraceStyle,
/// Which provenance to use for int2ptr casts
pub provenance_mode: ProvenanceMode,
/// Whether to ignore any output by the program. This is helpful when debugging miri
/// as its messages don't get intermingled with the program messages.
pub mute_stdout_stderr: bool,
/// The probability of the active thread being preempted at the end of each basic block.
pub preemption_rate: f64,
/// Report the current instruction being executed every N basic blocks.
pub report_progress: Option<u32>,
/// Whether Stacked Borrows and Tree Borrows retagging should recurse into fields of datatypes.
pub retag_fields: RetagFields,
/// The location of a shared object file to load when calling external functions
/// FIXME! consider allowing users to specify paths to multiple files, or to a directory
pub native_lib: Option<PathBuf>,
/// Run a garbage collector for BorTags every N basic blocks.
pub gc_interval: u32,
/// The number of CPUs to be reported by miri.
pub num_cpus: u32,
/// Requires Miri to emulate pages of a certain size
pub page_size: Option<u64>,
/// Whether to collect a backtrace when each allocation is created, just in case it leaks.
pub collect_leak_backtraces: bool,
/// Probability for address reuse.
pub address_reuse_rate: f64,
/// Probability for address reuse across threads.
pub address_reuse_cross_thread_rate: f64,
}
impl Default for MiriConfig {
fn default() -> MiriConfig {
MiriConfig {
env: vec![],
validation: ValidationMode::Shallow,
borrow_tracker: Some(BorrowTrackerMethod::StackedBorrows),
unique_is_unique: false,
check_alignment: AlignmentCheck::Int,
isolated_op: IsolatedOp::Reject(RejectOpWith::Abort),
ignore_leaks: false,
forwarded_env_vars: vec![],
set_env_vars: FxHashMap::default(),
args: vec![],
seed: None,
tracked_pointer_tags: FxHashSet::default(),
tracked_alloc_ids: FxHashSet::default(),
track_alloc_accesses: false,
data_race_detector: true,
weak_memory_emulation: true,
track_outdated_loads: false,
cmpxchg_weak_failure_rate: 0.8, // 80%
measureme_out: None,
panic_on_unsupported: false,
backtrace_style: BacktraceStyle::Short,
provenance_mode: ProvenanceMode::Default,
mute_stdout_stderr: false,
preemption_rate: 0.01, // 1%
report_progress: None,
retag_fields: RetagFields::Yes,
native_lib: None,
gc_interval: 10_000,
num_cpus: 1,
page_size: None,
collect_leak_backtraces: true,
address_reuse_rate: 0.5,
address_reuse_cross_thread_rate: 0.1,
}
}
}
/// The state of the main thread. Implementation detail of `on_main_stack_empty`.
#[derive(Default, Debug)]
enum MainThreadState<'tcx> {
#[default]
Running,
TlsDtors(tls::TlsDtorsState<'tcx>),
Yield {
remaining: u32,
},
Done,
}
impl<'tcx> MainThreadState<'tcx> {
fn on_main_stack_empty(
&mut self,
this: &mut MiriInterpCx<'tcx>,
) -> InterpResult<'tcx, Poll<()>> {
use MainThreadState::*;
match self {
Running => {
*self = TlsDtors(Default::default());
}
TlsDtors(state) =>
match state.on_stack_empty(this)? {
Poll::Pending => {} // just keep going
Poll::Ready(()) => {
// Give background threads a chance to finish by yielding the main thread a
// couple of times -- but only if we would also preempt threads randomly.
if this.machine.preemption_rate > 0.0 {
// There is a non-zero chance they will yield back to us often enough to
// make Miri terminate eventually.
*self = Yield { remaining: MAIN_THREAD_YIELDS_AT_SHUTDOWN };
} else {
// The other threads did not get preempted, so no need to yield back to
// them.
*self = Done;
}
}
},
Yield { remaining } =>
match remaining.checked_sub(1) {
None => *self = Done,
Some(new_remaining) => {
*remaining = new_remaining;
this.yield_active_thread();
}
},
Done => {
// Figure out exit code.
let ret_place = this.machine.main_fn_ret_place.clone().unwrap();
let exit_code = this.read_target_isize(&ret_place)?;
// Deal with our thread-local memory. We do *not* want to actually free it, instead we consider TLS
// to be like a global `static`, so that all memory reached by it is considered to "not leak".
this.terminate_active_thread(TlsAllocAction::Leak)?;
// Stop interpreter loop.
throw_machine_stop!(TerminationInfo::Exit { code: exit_code, leak_check: true });
}
}
Ok(Poll::Pending)
}
}
/// Returns a freshly created `InterpCx`.
/// Public because this is also used by `priroda`.
pub fn create_ecx<'tcx>(
tcx: TyCtxt<'tcx>,
entry_id: DefId,
entry_type: EntryFnType,
config: &MiriConfig,
) -> InterpResult<'tcx, InterpCx<'tcx, MiriMachine<'tcx>>> {
let param_env = ty::ParamEnv::reveal_all();
let layout_cx = LayoutCx { tcx, param_env };
let mut ecx =
InterpCx::new(tcx, rustc_span::DUMMY_SP, param_env, MiriMachine::new(config, layout_cx));
// Some parts of initialization require a full `InterpCx`.
MiriMachine::late_init(&mut ecx, config, {
let mut state = MainThreadState::default();
// Cannot capture anything GC-relevant here.
Box::new(move |m| state.on_main_stack_empty(m))
})?;
// Make sure we have MIR. We check MIR for some stable monomorphic function in libcore.
let sentinel =
helpers::try_resolve_path(tcx, &["core", "ascii", "escape_default"], Namespace::ValueNS);
if !matches!(sentinel, Some(s) if tcx.is_mir_available(s.def.def_id())) {
tcx.dcx().fatal(
"the current sysroot was built without `-Zalways-encode-mir`, or libcore seems missing. \
Use `cargo miri setup` to prepare a sysroot that is suitable for Miri."
);
}
// Setup first stack frame.
let entry_instance = ty::Instance::mono(tcx, entry_id);
// First argument is constructed later, because it's skipped if the entry function uses #[start].
// Second argument (argc): length of `config.args`.
let argc =
ImmTy::from_int(i64::try_from(config.args.len()).unwrap(), ecx.machine.layouts.isize);
// Third argument (`argv`): created from `config.args`.
let argv = {
// Put each argument in memory, collect pointers.
let mut argvs = Vec::<Immediate<Provenance>>::with_capacity(config.args.len());
for arg in config.args.iter() {
// Make space for `0` terminator.
let size = u64::try_from(arg.len()).unwrap().strict_add(1);
let arg_type = Ty::new_array(tcx, tcx.types.u8, size);
let arg_place =
ecx.allocate(ecx.layout_of(arg_type)?, MiriMemoryKind::Machine.into())?;
ecx.write_os_str_to_c_str(OsStr::new(arg), arg_place.ptr(), size)?;
ecx.mark_immutable(&arg_place);
argvs.push(arg_place.to_ref(&ecx));
}
// Make an array with all these pointers, in the Miri memory.
let argvs_layout = ecx.layout_of(Ty::new_array(
tcx,
Ty::new_imm_ptr(tcx, tcx.types.u8),
u64::try_from(argvs.len()).unwrap(),
))?;
let argvs_place = ecx.allocate(argvs_layout, MiriMemoryKind::Machine.into())?;
for (idx, arg) in argvs.into_iter().enumerate() {
let place = ecx.project_field(&argvs_place, idx)?;
ecx.write_immediate(arg, &place)?;
}
ecx.mark_immutable(&argvs_place);
// Store `argc` and `argv` for macOS `_NSGetArg{c,v}`.
{
let argc_place =
ecx.allocate(ecx.machine.layouts.isize, MiriMemoryKind::Machine.into())?;
ecx.write_immediate(*argc, &argc_place)?;
ecx.mark_immutable(&argc_place);
ecx.machine.argc = Some(argc_place.ptr());
let argv_place = ecx.allocate(
ecx.layout_of(Ty::new_imm_ptr(tcx, tcx.types.unit))?,
MiriMemoryKind::Machine.into(),
)?;
ecx.write_pointer(argvs_place.ptr(), &argv_place)?;
ecx.mark_immutable(&argv_place);
ecx.machine.argv = Some(argv_place.ptr());
}
// Store command line as UTF-16 for Windows `GetCommandLineW`.
{
// Construct a command string with all the arguments.
let cmd_utf16: Vec<u16> = args_to_utf16_command_string(config.args.iter());
let cmd_type =
Ty::new_array(tcx, tcx.types.u16, u64::try_from(cmd_utf16.len()).unwrap());
let cmd_place =
ecx.allocate(ecx.layout_of(cmd_type)?, MiriMemoryKind::Machine.into())?;
ecx.machine.cmd_line = Some(cmd_place.ptr());
// Store the UTF-16 string. We just allocated so we know the bounds are fine.
for (idx, &c) in cmd_utf16.iter().enumerate() {
let place = ecx.project_field(&cmd_place, idx)?;
ecx.write_scalar(Scalar::from_u16(c), &place)?;
}
ecx.mark_immutable(&cmd_place);
}
ecx.mplace_to_ref(&argvs_place)?
};
// Return place (in static memory so that it does not count as leak).
let ret_place = ecx.allocate(ecx.machine.layouts.isize, MiriMemoryKind::Machine.into())?;
ecx.machine.main_fn_ret_place = Some(ret_place.clone());
// Call start function.
match entry_type {
EntryFnType::Main { .. } => {
let start_id = tcx.lang_items().start_fn().unwrap_or_else(|| {
tcx.dcx().fatal(
"could not find start function. Make sure the entry point is marked with `#[start]`."
);
});
let main_ret_ty = tcx.fn_sig(entry_id).no_bound_vars().unwrap().output();
let main_ret_ty = main_ret_ty.no_bound_vars().unwrap();
let start_instance = ty::Instance::try_resolve(
tcx,
ty::ParamEnv::reveal_all(),
start_id,
tcx.mk_args(&[ty::GenericArg::from(main_ret_ty)]),
)
.unwrap()
.unwrap();
let main_ptr = ecx.fn_ptr(FnVal::Instance(entry_instance));
// Always using DEFAULT is okay since we don't support signals in Miri anyway.
// (This means we are effectively ignoring `-Zon-broken-pipe`.)
let sigpipe = rustc_session::config::sigpipe::DEFAULT;
ecx.call_function(
start_instance,
Abi::Rust,
&[
ImmTy::from_scalar(
Scalar::from_pointer(main_ptr, &ecx),
// FIXME use a proper fn ptr type
ecx.machine.layouts.const_raw_ptr,
),
argc,
argv,
ImmTy::from_uint(sigpipe, ecx.machine.layouts.u8),
],
Some(&ret_place),
StackPopCleanup::Root { cleanup: true },
)?;
}
EntryFnType::Start => {
ecx.call_function(
entry_instance,
Abi::Rust,
&[argc, argv],
Some(&ret_place),
StackPopCleanup::Root { cleanup: true },
)?;
}
}
Ok(ecx)
}
/// Evaluates the entry function specified by `entry_id`.
/// Returns `Some(return_code)` if program executed completed.
/// Returns `None` if an evaluation error occurred.
#[allow(clippy::needless_lifetimes)]
pub fn eval_entry<'tcx>(
tcx: TyCtxt<'tcx>,
entry_id: DefId,
entry_type: EntryFnType,
config: MiriConfig,
) -> Option<i64> {
// Copy setting before we move `config`.
let ignore_leaks = config.ignore_leaks;
let mut ecx = match create_ecx(tcx, entry_id, entry_type, &config) {
Ok(v) => v,
Err(err) => {
let (kind, backtrace) = err.into_parts();
backtrace.print_backtrace();
panic!("Miri initialization error: {kind:?}")
}
};
// Perform the main execution.
let res: thread::Result<InterpResult<'_, !>> =
panic::catch_unwind(AssertUnwindSafe(|| ecx.run_threads()));
let res = res.unwrap_or_else(|panic_payload| {
ecx.handle_ice();
panic::resume_unwind(panic_payload)
});
// `Ok` can never happen.
#[cfg(not(bootstrap))]
let Err(res) = res;
#[cfg(bootstrap)]
let res = match res {
Err(res) => res,
// `Ok` can never happen
Ok(never) => match never {},
};
// Machine cleanup. Only do this if all threads have terminated; threads that are still running
// might cause Stacked Borrows errors (https://github.com/rust-lang/miri/issues/2396).
if ecx.have_all_terminated() {
// Even if all threads have terminated, we have to beware of data races since some threads
// might not have joined the main thread (https://github.com/rust-lang/miri/issues/2020,
// https://github.com/rust-lang/miri/issues/2508).
ecx.allow_data_races_all_threads_done();
EnvVars::cleanup(&mut ecx).expect("error during env var cleanup");
}
// Process the result.
let (return_code, leak_check) = report_error(&ecx, res)?;
if leak_check && !ignore_leaks {
// Check for thread leaks.
if !ecx.have_all_terminated() {
tcx.dcx().err("the main thread terminated without waiting for all remaining threads");
tcx.dcx().note("set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check");
return None;
}
// Check for memory leaks.
info!("Additional static roots: {:?}", ecx.machine.static_roots);
let leaks = ecx.find_leaked_allocations(&ecx.machine.static_roots);
if !leaks.is_empty() {
report_leaks(&ecx, leaks);
tcx.dcx().note("set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check");
// Ignore the provided return code - let the reported error
// determine the return code.
return None;
}
}
Some(return_code)
}
/// Turns an array of arguments into a Windows command line string.
///
/// The string will be UTF-16 encoded and NUL terminated.
///
/// Panics if the zeroth argument contains the `"` character because doublequotes
/// in `argv[0]` cannot be encoded using the standard command line parsing rules.
///
/// Further reading:
/// * [Parsing C++ command-line arguments](https://docs.microsoft.com/en-us/cpp/cpp/main-function-command-line-args?view=msvc-160#parsing-c-command-line-arguments)
/// * [The C/C++ Parameter Parsing Rules](https://daviddeley.com/autohotkey/parameters/parameters.htm#WINCRULES)
fn args_to_utf16_command_string<I, T>(mut args: I) -> Vec<u16>
where
I: Iterator<Item = T>,
T: AsRef<str>,
{
// Parse argv[0]. Slashes aren't escaped. Literal double quotes are not allowed.
let mut cmd = {
let arg0 = if let Some(arg0) = args.next() {
arg0
} else {
return vec![0];
};
let arg0 = arg0.as_ref();
if arg0.contains('"') {
panic!("argv[0] cannot contain a doublequote (\") character");
} else {
// Always surround argv[0] with quotes.
let mut s = String::new();
s.push('"');
s.push_str(arg0);
s.push('"');
s
}
};
// Build the other arguments.
for arg in args {
let arg = arg.as_ref();
cmd.push(' ');
if arg.is_empty() {
cmd.push_str("\"\"");
} else if !arg.bytes().any(|c| matches!(c, b'"' | b'\t' | b' ')) {
// No quote, tab, or space -- no escaping required.
cmd.push_str(arg);
} else {
// Spaces and tabs are escaped by surrounding them in quotes.
// Quotes are themselves escaped by using backslashes when in a
// quoted block.
// Backslashes only need to be escaped when one or more are directly
// followed by a quote. Otherwise they are taken literally.
cmd.push('"');
let mut chars = arg.chars().peekable();
loop {
let mut nslashes = 0;
while let Some(&'\\') = chars.peek() {
chars.next();
nslashes += 1;
}
match chars.next() {
Some('"') => {
cmd.extend(iter::repeat('\\').take(nslashes * 2 + 1));
cmd.push('"');
}
Some(c) => {
cmd.extend(iter::repeat('\\').take(nslashes));
cmd.push(c);
}
None => {
cmd.extend(iter::repeat('\\').take(nslashes * 2));
break;
}
}
}
cmd.push('"');
}
}
if cmd.contains('\0') {
panic!("interior null in command line arguments");
}
cmd.encode_utf16().chain(iter::once(0)).collect()
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
#[should_panic(expected = "argv[0] cannot contain a doublequote (\") character")]
fn windows_argv0_panic_on_quote() {
args_to_utf16_command_string(["\""].iter());
}
#[test]
fn windows_argv0_no_escape() {
// Ensure that a trailing backslash in argv[0] is not escaped.
let cmd = String::from_utf16_lossy(&args_to_utf16_command_string(
[r"C:\Program Files\", "arg1", "arg 2", "arg \" 3"].iter(),
));
assert_eq!(cmd.trim_end_matches('\0'), r#""C:\Program Files\" arg1 "arg 2" "arg \" 3""#);
}
}