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Auto merge of #3478 - RalfJung:alloc_error_handler, r=RalfJung
implement support for __rust_alloc_error_handler Fixes rust-lang/miri#3439
2 parents 7197990 + f325c8d commit 8ad72b2

10 files changed

+207
-7
lines changed

‎src/tools/miri/src/shims/extern_static.rs

+6-1
Original file line numberDiff line numberDiff line change
@@ -32,9 +32,14 @@ impl<'mir, 'tcx> MiriMachine<'mir, 'tcx> {
3232
/// Sets up the "extern statics" for this machine.
3333
pub fn init_extern_statics(this: &mut MiriInterpCx<'mir, 'tcx>) -> InterpResult<'tcx> {
3434
// "__rust_no_alloc_shim_is_unstable"
35-
let val = ImmTy::from_int(0, this.machine.layouts.u8);
35+
let val = ImmTy::from_int(0, this.machine.layouts.u8); // always 0, value does not matter
3636
Self::alloc_extern_static(this, "__rust_no_alloc_shim_is_unstable", val)?;
3737

38+
// "__rust_alloc_error_handler_should_panic"
39+
let val = this.tcx.sess.opts.unstable_opts.oom.should_panic();
40+
let val = ImmTy::from_int(val, this.machine.layouts.u8);
41+
Self::alloc_extern_static(this, "__rust_alloc_error_handler_should_panic", val)?;
42+
3843
match this.tcx.sess.target.os.as_ref() {
3944
"linux" => {
4045
Self::null_ptr_extern_statics(

‎src/tools/miri/src/shims/foreign_items.rs

+15-1
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,7 @@
11
use std::{collections::hash_map::Entry, io::Write, iter, path::Path};
22

33
use rustc_apfloat::Float;
4-
use rustc_ast::expand::allocator::AllocatorKind;
4+
use rustc_ast::expand::allocator::{alloc_error_handler_name, AllocatorKind};
55
use rustc_hir::{def::DefKind, def_id::CrateNum};
66
use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
77
use rustc_middle::mir;
@@ -80,6 +80,20 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
8080
panic_impl_instance,
8181
)));
8282
}
83+
"__rust_alloc_error_handler" => {
84+
// Forward to the right symbol that implements this function.
85+
let Some(handler_kind) = this.tcx.alloc_error_handler_kind(()) else {
86+
// in real code, this symbol does not exist without an allocator
87+
throw_unsup_format!(
88+
"`__rust_alloc_error_handler` cannot be called when no alloc error handler is set"
89+
);
90+
};
91+
let name = alloc_error_handler_name(handler_kind);
92+
let handler = this
93+
.lookup_exported_symbol(Symbol::intern(name))?
94+
.expect("missing alloc error handler symbol");
95+
return Ok(Some(handler));
96+
}
8397
#[rustfmt::skip]
8498
| "exit"
8599
| "ExitProcess"

‎src/tools/miri/tests/fail/alloc/alloc_error_handler.rs

+25
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,25 @@
1+
//@error-in-other-file: aborted
2+
//@normalize-stderr-test: "unsafe \{ libc::abort\(\) \}|crate::intrinsics::abort\(\);" -> "ABORT();"
3+
//@normalize-stderr-test: "\| +\^+" -> "| ^"
4+
#![feature(allocator_api)]
5+
6+
use std::alloc::*;
7+
use std::ptr::NonNull;
8+
9+
struct BadAlloc;
10+
11+
// Create a failing allocator; Miri's native allocator never fails so this is the only way to
12+
// actually call the alloc error handler.
13+
unsafe impl Allocator for BadAlloc {
14+
fn allocate(&self, _l: Layout) -> Result<NonNull<[u8]>, AllocError> {
15+
Err(AllocError)
16+
}
17+
18+
unsafe fn deallocate(&self, _ptr: NonNull<u8>, _layout: Layout) {
19+
unreachable!();
20+
}
21+
}
22+
23+
fn main() {
24+
let _b = Box::new_in(0, BadAlloc);
25+
}

‎src/tools/miri/tests/fail/alloc/alloc_error_handler.stderr

+26
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,26 @@
1+
memory allocation of 4 bytes failed
2+
error: abnormal termination: the program aborted execution
3+
--> RUSTLIB/std/src/sys/pal/PLATFORM/mod.rs:LL:CC
4+
|
5+
LL | ABORT();
6+
| ^ the program aborted execution
7+
|
8+
= note: BACKTRACE:
9+
= note: inside `std::sys::pal::PLATFORM::abort_internal` at RUSTLIB/std/src/sys/pal/PLATFORM/mod.rs:LL:CC
10+
= note: inside `std::process::abort` at RUSTLIB/std/src/process.rs:LL:CC
11+
= note: inside `std::alloc::rust_oom` at RUSTLIB/std/src/alloc.rs:LL:CC
12+
= note: inside `std::alloc::_::__rg_oom` at RUSTLIB/std/src/alloc.rs:LL:CC
13+
= note: inside `std::alloc::handle_alloc_error::rt_error` at RUSTLIB/alloc/src/alloc.rs:LL:CC
14+
= note: inside `std::alloc::handle_alloc_error` at RUSTLIB/alloc/src/alloc.rs:LL:CC
15+
= note: inside `std::boxed::Box::<i32, BadAlloc>::new_uninit_in` at RUSTLIB/alloc/src/boxed.rs:LL:CC
16+
= note: inside `std::boxed::Box::<i32, BadAlloc>::new_in` at RUSTLIB/alloc/src/boxed.rs:LL:CC
17+
note: inside `main`
18+
--> $DIR/alloc_error_handler.rs:LL:CC
19+
|
20+
LL | let _b = Box::new_in(0, BadAlloc);
21+
| ^
22+
23+
note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
24+
25+
error: aborting due to 1 previous error
26+

‎src/tools/miri/tests/fail/alloc/alloc_error_handler_no_std.rs

+65
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,65 @@
1+
//@compile-flags: -Cpanic=abort
2+
#![feature(start, core_intrinsics)]
3+
#![feature(alloc_error_handler)]
4+
#![feature(allocator_api)]
5+
#![no_std]
6+
7+
extern crate alloc;
8+
9+
use alloc::alloc::*;
10+
use alloc::boxed::Box;
11+
use core::ptr::NonNull;
12+
13+
struct BadAlloc;
14+
15+
// Create a failing allocator; that is the only way to actually call the alloc error handler.
16+
unsafe impl Allocator for BadAlloc {
17+
fn allocate(&self, _l: Layout) -> Result<NonNull<[u8]>, AllocError> {
18+
Err(AllocError)
19+
}
20+
21+
unsafe fn deallocate(&self, _ptr: NonNull<u8>, _layout: Layout) {
22+
unreachable!();
23+
}
24+
}
25+
26+
#[alloc_error_handler]
27+
fn alloc_error_handler(_: Layout) -> ! {
28+
extern "Rust" {
29+
fn miri_write_to_stderr(bytes: &[u8]);
30+
}
31+
let msg = "custom alloc error handler called!\n";
32+
unsafe { miri_write_to_stderr(msg.as_bytes()) };
33+
core::intrinsics::abort(); //~ERROR: aborted
34+
}
35+
36+
// rustc requires us to provide some more things that aren't actually used by this test
37+
mod plumbing {
38+
use super::*;
39+
40+
#[panic_handler]
41+
fn panic_handler(_: &core::panic::PanicInfo) -> ! {
42+
core::intrinsics::abort();
43+
}
44+
45+
struct NoAlloc;
46+
47+
unsafe impl GlobalAlloc for NoAlloc {
48+
unsafe fn alloc(&self, _: Layout) -> *mut u8 {
49+
unreachable!();
50+
}
51+
52+
unsafe fn dealloc(&self, _: *mut u8, _: Layout) {
53+
unreachable!();
54+
}
55+
}
56+
57+
#[global_allocator]
58+
static GLOBAL: NoAlloc = NoAlloc;
59+
}
60+
61+
#[start]
62+
fn start(_: isize, _: *const *const u8) -> isize {
63+
let _b = Box::new_in(0, BadAlloc);
64+
0
65+
}

‎src/tools/miri/tests/fail/alloc/alloc_error_handler_no_std.stderr

+29
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,29 @@
1+
custom alloc error handler called!
2+
error: abnormal termination: the program aborted execution
3+
--> $DIR/alloc_error_handler_no_std.rs:LL:CC
4+
|
5+
LL | core::intrinsics::abort();
6+
| ^^^^^^^^^^^^^^^^^^^^^^^^^ the program aborted execution
7+
|
8+
= note: BACKTRACE:
9+
= note: inside `alloc_error_handler` at $DIR/alloc_error_handler_no_std.rs:LL:CC
10+
note: inside `_::__rg_oom`
11+
--> $DIR/alloc_error_handler_no_std.rs:LL:CC
12+
|
13+
LL | #[alloc_error_handler]
14+
| ---------------------- in this procedural macro expansion
15+
LL | fn alloc_error_handler(_: Layout) -> ! {
16+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
17+
= note: inside `alloc::alloc::handle_alloc_error::rt_error` at RUSTLIB/alloc/src/alloc.rs:LL:CC
18+
= note: inside `alloc::alloc::handle_alloc_error` at RUSTLIB/alloc/src/alloc.rs:LL:CC
19+
= note: inside `alloc::boxed::Box::<i32, BadAlloc>::new_uninit_in` at RUSTLIB/alloc/src/boxed.rs:LL:CC
20+
= note: inside `alloc::boxed::Box::<i32, BadAlloc>::new_in` at RUSTLIB/alloc/src/boxed.rs:LL:CC
21+
note: inside `start`
22+
--> $DIR/alloc_error_handler_no_std.rs:LL:CC
23+
|
24+
LL | let _b = Box::new_in(0, BadAlloc);
25+
| ^^^^^^^^^^^^^^^^^^^^^^^^
26+
= note: this error originates in the attribute macro `alloc_error_handler` (in Nightly builds, run with -Z macro-backtrace for more info)
27+
28+
error: aborting due to 1 previous error
29+

‎src/tools/miri/tests/panic/alloc_error_handler_panic.rs

+32
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,32 @@
1+
//@compile-flags: -Zoom=panic
2+
#![feature(allocator_api)]
3+
4+
use std::alloc::*;
5+
use std::ptr::NonNull;
6+
7+
struct BadAlloc;
8+
9+
// Create a failing allocator; Miri's native allocator never fails so this is the only way to
10+
// actually call the alloc error handler.
11+
unsafe impl Allocator for BadAlloc {
12+
fn allocate(&self, _l: Layout) -> Result<NonNull<[u8]>, AllocError> {
13+
Err(AllocError)
14+
}
15+
16+
unsafe fn deallocate(&self, _ptr: NonNull<u8>, _layout: Layout) {
17+
unreachable!();
18+
}
19+
}
20+
21+
struct Bomb;
22+
impl Drop for Bomb {
23+
fn drop(&mut self) {
24+
eprintln!("yes we are unwinding!");
25+
}
26+
}
27+
28+
fn main() {
29+
let bomb = Bomb;
30+
let _b = Box::new_in(0, BadAlloc);
31+
std::mem::forget(bomb); // defuse unwinding bomb
32+
}

‎src/tools/miri/tests/panic/alloc_error_handler_panic.stderr

+4
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,4 @@
1+
thread 'main' panicked at RUSTLIB/std/src/alloc.rs:LL:CC:
2+
memory allocation of 4 bytes failed
3+
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
4+
yes we are unwinding!

‎src/tools/miri/tests/pass/alloc-access-tracking.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,6 @@
11
#![feature(start)]
22
#![no_std]
3-
//@compile-flags: -Zmiri-track-alloc-id=17 -Zmiri-track-alloc-accesses -Cpanic=abort
3+
//@compile-flags: -Zmiri-track-alloc-id=18 -Zmiri-track-alloc-accesses -Cpanic=abort
44
//@only-target-linux: alloc IDs differ between OSes for some reason
55

66
extern "Rust" {

‎src/tools/miri/tests/pass/alloc-access-tracking.stderr

+4-4
Original file line numberDiff line numberDiff line change
@@ -2,7 +2,7 @@ note: tracking was triggered
22
--> $DIR/alloc-access-tracking.rs:LL:CC
33
|
44
LL | let ptr = miri_alloc(123, 1);
5-
| ^^^^^^^^^^^^^^^^^^ created Miri bare-metal heap allocation of 123 bytes (alignment ALIGN bytes) with id 17
5+
| ^^^^^^^^^^^^^^^^^^ created Miri bare-metal heap allocation of 123 bytes (alignment ALIGN bytes) with id 18
66
|
77
= note: BACKTRACE:
88
= note: inside `start` at $DIR/alloc-access-tracking.rs:LL:CC
@@ -11,7 +11,7 @@ note: tracking was triggered
1111
--> $DIR/alloc-access-tracking.rs:LL:CC
1212
|
1313
LL | *ptr = 42; // Crucially, only a write is printed here, no read!
14-
| ^^^^^^^^^ write access to allocation with id 17
14+
| ^^^^^^^^^ write access to allocation with id 18
1515
|
1616
= note: BACKTRACE:
1717
= note: inside `start` at $DIR/alloc-access-tracking.rs:LL:CC
@@ -20,7 +20,7 @@ note: tracking was triggered
2020
--> $DIR/alloc-access-tracking.rs:LL:CC
2121
|
2222
LL | assert_eq!(*ptr, 42);
23-
| ^^^^^^^^^^^^^^^^^^^^ read access to allocation with id 17
23+
| ^^^^^^^^^^^^^^^^^^^^ read access to allocation with id 18
2424
|
2525
= note: BACKTRACE:
2626
= note: inside `start` at RUSTLIB/core/src/macros/mod.rs:LL:CC
@@ -30,7 +30,7 @@ note: tracking was triggered
3030
--> $DIR/alloc-access-tracking.rs:LL:CC
3131
|
3232
LL | miri_dealloc(ptr, 123, 1);
33-
| ^^^^^^^^^^^^^^^^^^^^^^^^^ freed allocation with id 17
33+
| ^^^^^^^^^^^^^^^^^^^^^^^^^ freed allocation with id 18
3434
|
3535
= note: BACKTRACE:
3636
= note: inside `start` at $DIR/alloc-access-tracking.rs:LL:CC

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