bjoernager/rust
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Install more signal stack trace handlers

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This commit is contained in:
Urgau 2025-02-16 22:16:31 +01:00
parent 4229b80f50
commit a0a8e02e66
1 changed files with 39 additions and 11 deletions
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50
compiler/rustc_driver_impl/src/signal_handler.rs
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@ -6,6 +6,15 @@ use std::{fmt, mem, ptr, slice};
use rustc_interface::util::{DEFAULT_STACK_SIZE, STACK_SIZE};
/// Signals that represent that we have a bug, and our prompt termination has
/// been ordered.
#[rustfmt::skip]
const KILL_SIGNALS: [(libc::c_int, &str); 3] = [
(libc::SIGILL, "SIGILL"),
(libc::SIGBUS, "SIGBUS"),
(libc::SIGSEGV, "SIGSEGV")
];
unsafe extern "C" {
fn backtrace_symbols_fd(buffer: *const *mut libc::c_void, size: libc::c_int, fd: libc::c_int);
}
@ -39,8 +48,19 @@ macro raw_errln($tokens:tt) {
/// # Safety
///
/// Caller must ensure that this function is not re-entered.
unsafe extern "C" fn print_stack_trace(_: libc::c_int) {
unsafe extern "C" fn print_stack_trace(signum: libc::c_int) {
const MAX_FRAMES: usize = 256;
let signame = {
let mut signame = "<unknown>";
for sig in KILL_SIGNALS {
if sig.0 == signum {
signame = sig.1;
}
}
signame
};
let stack = unsafe {
// Reserve data segment so we don't have to malloc in a signal handler, which might fail
// in incredibly undesirable and unexpected ways due to e.g. the allocator deadlocking
@ -54,7 +74,8 @@ unsafe extern "C" fn print_stack_trace(_: libc::c_int) {
};
// Just a stack trace is cryptic. Explain what we're doing.
raw_errln!("error: rustc interrupted by SIGSEGV, printing backtrace\n");
raw_errln!("error: rustc interrupted by {signame}, printing backtrace\n");
let mut written = 1;
let mut consumed = 0;
// Begin elaborating return addrs into symbols and writing them directly to stderr
@ -94,7 +115,7 @@ unsafe extern "C" fn print_stack_trace(_: libc::c_int) {
written += rem.len() + 1;
let random_depth = || 8 * 16; // chosen by random diceroll (2d20)
if cyclic || stack.len() > random_depth() {
if (cyclic || stack.len() > random_depth()) && signum == libc::SIGSEGV {
// technically speculation, but assert it with confidence anyway.
// rustc only arrived in this signal handler because bad things happened
// and this message is for explaining it's not the programmer's fault
@ -106,17 +127,22 @@ unsafe extern "C" fn print_stack_trace(_: libc::c_int) {
written += 1;
}
raw_errln!("note: we would appreciate a report at https://github.com/rust-lang/rust");
// get the current stack size WITHOUT blocking and double it
let new_size = STACK_SIZE.get().copied().unwrap_or(DEFAULT_STACK_SIZE) * 2;
raw_errln!("help: you can increase rustc's stack size by setting RUST_MIN_STACK={new_size}");
written += 2;
written += 1;
if signum == libc::SIGSEGV {
// get the current stack size WITHOUT blocking and double it
let new_size = STACK_SIZE.get().copied().unwrap_or(DEFAULT_STACK_SIZE) * 2;
raw_errln!(
"help: you can increase rustc's stack size by setting RUST_MIN_STACK={new_size}"
);
written += 1;
}
if written > 24 {
// We probably just scrolled the earlier "we got SIGSEGV" message off the terminal
raw_errln!("note: backtrace dumped due to SIGSEGV! resuming signal");
// We probably just scrolled the earlier "interrupted by {signame}" message off the terminal
raw_errln!("note: backtrace dumped due to {signame}! resuming signal");
};
}
/// When SIGSEGV is delivered to the process, print a stack trace and then exit.
/// When one of the KILL signals is delivered to the process, print a stack trace and then exit.
pub(super) fn install() {
unsafe {
let alt_stack_size: usize = min_sigstack_size() + 64 * 1024;
@ -129,7 +155,9 @@ pub(super) fn install() {
sa.sa_sigaction = print_stack_trace as libc::sighandler_t;
sa.sa_flags = libc::SA_NODEFER | libc::SA_RESETHAND | libc::SA_ONSTACK;
libc::sigemptyset(&mut sa.sa_mask);
libc::sigaction(libc::SIGSEGV, &sa, ptr::null_mut());
for (signum, _signame) in KILL_SIGNALS {
libc::sigaction(signum, &sa, ptr::null_mut());
}
}
}