intptrcast: Never allocate two objects directly adjecent
When two objects directly follow each other in memory, what is the
provenance of an integer cast to a pointer that points directly between
them? For a zero-size region, it could point into the end of the first
object, or the start of the second.
We can avoid answering this difficult question by simply never
allocating two objects directly beside each other. This fixes some of
the false positives from #1866.
When two objects directly follow each other in memory, what is the
provenance of an integer cast to a pointer that points directly between
them? For a zero-size region, it could point into the end of the first
object, or the start of the second.
We can avoid answering this difficult question by simply never
allocating two objects directly beside each other. This fixes some of
the false positives from #1866.
also ignore 'thread leaks' with -Zmiri-ignore-leaks
This is a step towards https://github.com/rust-lang/miri/issues/1371. The remaining hard part would be supporting checking for memory leaks when there are threads still running. For now we elegantly avoid this problem by using the same flag to control both of these checks. :)
Change the code to either `EACCES` (if the op is performed on the
path), or `EBADF` (if the op is performed the fd)
Updated ops: `stat`, `opendir`, `ftruncate64`, and `readlink`
Add a new test for fs ops in isolation.
Report an error if a `#[no_mangle]`/`#[export_name = ...]` function has the same symbol name as a built-in shim
Implements https://github.com/rust-lang/miri/pull/1776#issuecomment-821322605.
The error looks like this:
```
error: found `malloc` symbol definition that clashes with a built-in shim
--> tests/compile-fail/function_calls/exported_symbol_shim_clashing.rs:12:9
|
12 | malloc(0);
| ^^^^^^^^^ found `malloc` symbol definition that clashes with a built-in shim
|
help: the `malloc` symbol is defined here
--> tests/compile-fail/function_calls/exported_symbol_shim_clashing.rs:2:1
|
2 | / extern "C" fn malloc(_: usize) -> *mut std::ffi::c_void {
3 | | //~^ HELP the `malloc` symbol is defined here
4 | | unreachable!()
5 | | }
| |_^
= note: inside `main` at tests/compile-fail/function_calls/exported_symbol_shim_clashing.rs:12:9
```
This does not implement "better error messages than we do currently for arg/ABI mismatches" in https://github.com/rust-lang/miri/pull/1776#issuecomment-821343175 -- I failed to remove all `check_arg_count()` and `check_abi()` (they are still used in `src/shims/intrinsics.rs` and `call_dlsym()`) and they don't receive the name of the shim.
Add support for panicking in the emulated application when unsupported functionality is encountered
This PR fixes#1807 and allows an optional flag to be specified to panic when an unsupported syscall is encountered. In essence, instead of bubbling up an error in the context of the Miri application Miri will panic within the context of the *emulated* application. This feature is desired to allow CI pipelines to determine if a Miri failure is unsupported functionality or actual UB. Please read [this comment](https://github.com/rust-lang/miri/issues/1807#issuecomment-845425076) for the rationale behind this change.
Note: this change does not cover all cases where unsupported functionality errors may be raised. If you search the repo for `throw_unsup_format!` there are many cases that I think are less likely to occur and may still be problematic for some folks.
TODO:
- [x] README documentation on this new flag
- [x] Add tests
In user interface, added a new flag `-Zmiri-isolation-error` which
takes one of the four values -- hide, warn, warn-nobacktrace, and
abort. This option can be used to configure Miri to either abort or
return an error code upon executing isolated op. If not aborted, Miri
prints a warning, whose verbosity can be configured using this flag.
In implementation, added a new enum `IsolatedOp` to capture all the
settings related to ops requiring communication with the
host. Old `communicate` flag in both miri configs and machine
stats is replaced with a new helper function `communicate()` which
checks `isolated_op` internally.
Added a new helper function `reject_in_isolation` which can be called
by shims to reject ops according to the reject_with settings. Use miri
specific diagnostics function `report_msg` to print backtrace in the
warning. Update it to take an enum value instead of a bool, indicating
the level of diagnostics.
Updated shims related to current dir to use the new APIs. Added a new
test for current dir ops in isolation without halting machine.
Add random failures to compare_exchange_weak
In practice this is pretty useful for detecting bugs.
This fails more frequently than realistic (~~50%~~ (now 80%, controlled by a flag) of the time). I couldn't find any existing code that tries to model this (tsan, cdschecker, etc all seem to have TODOs there). Relacy models it with a 25% or 50% failure chance depending on some settings.
CC `@JCTyblaidd` who wrote the code this modifies initially, and seems interested in this subject.
Weaken release sequences to match the C++20 memory model
See [Weaken Release Sequences](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0982r1.html), since the exception for relaxed writes on the same thread as a release write not blocking release sequences was removed in the C++20 memory model compared to the C11 memory model the paper was based on. The implementation can be updated and simplified to match this. [Rust is currently specified to use the C++20 memory model](https://doc.rust-lang.org/std/sync/atomic/index.html).
