Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly
Sign up
Appearance settings

Commit 772f380

Browse files
committed
Auto merge of #147090 - Noratrieb:immediate-abort-stack-overflow, r=joboet
Skip stack overflow handler for panic=immediate-abort std installs guard pages and a signal handler to ensure that stackoverflows 1) terminate abruptly and 2) print an nice message. Even for panic=immediate-abort, 1) is desirable, we don't want silent data corruption there. But 2) is completely unnecessary, as users deliberately *don't* want nice messages, they want minimum binary size. Therefore, skip the entire guard signal handler setup, which saves a lot of bytes. I tested this with a hello world binary using fat LTO, build-std, panic=immediate-abort, opt-level=s, strip=debuginfo. `size` reports significant savings: ``` text data bss dec hex filename 15252 1032 104 16388 4004 tiny-before 6881 964 48 7893 1ed5 tiny-after2 ``` `nm -U` goes from 71 to 56, getting rid of a bunch of stack overflow related symbols. The disk size goes from `31k` to `24k`. The impact on the error message is minimal, as the message was already missing. before: ``` fish: Job 1, './tiny-so-before' terminated by signal SIGABRT (Abort) ``` after: ``` fish: Job 1, './tiny-so-after' terminated by signal SIGSEGV (Address boundary error) ``` I didn't test the Windows part, but it likely also has savings.
2 parents f957826 + 660a348 commit 772f380

File tree

2 files changed

+13
-2
lines changed

2 files changed

+13
-2
lines changed

‎library/std/src/sys/pal/unix/stack_overflow.rs‎

Lines changed: 11 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -148,6 +148,13 @@ mod imp {
148148

149149
let mut guard_page_range = unsafe { install_main_guard() };
150150

151+
// Even for panic=immediate-abort, installing the guard pages is important for soundness.
152+
// That said, we do not care about giving nice stackoverflow messages via our custom
153+
// signal handler, just exit early and let the user enjoy the segfault.
154+
if cfg!(panic = "immediate-abort") {
155+
return;
156+
}
157+
151158
// SAFETY: assuming all platforms define struct sigaction as "zero-initializable"
152159
let mut action: sigaction = unsafe { mem::zeroed() };
153160
for &signal in &[SIGSEGV, SIGBUS] {
@@ -179,6 +186,9 @@ mod imp {
179186
/// Must be called only once
180187
#[forbid(unsafe_op_in_unsafe_fn)]
181188
pub unsafe fn cleanup() {
189+
if cfg!(panic = "immediate-abort") {
190+
return;
191+
}
182192
// FIXME: I probably cause more bugs than I'm worth!
183193
// see https://github.com/rust-lang/rust/issues/111272
184194
unsafe { drop_handler(MAIN_ALTSTACK.load(Ordering::Relaxed)) };
@@ -230,7 +240,7 @@ mod imp {
230240
/// Mutates the alternate signal stack
231241
#[forbid(unsafe_op_in_unsafe_fn)]
232242
pub unsafe fn make_handler(main_thread: bool, thread_name: Option<Box<str>>) -> Handler {
233-
if !NEED_ALTSTACK.load(Ordering::Acquire) {
243+
if cfg!(panic = "immediate-abort") || !NEED_ALTSTACK.load(Ordering::Acquire) {
234244
return Handler::null();
235245
}
236246

‎library/std/src/sys/pal/windows/mod.rs‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -22,7 +22,8 @@ pub mod os;
2222
pub mod pipe;
2323
pub mod time;
2424
cfg_select! {
25-
not(target_vendor = "uwp") => {
25+
// We don't care about printing nice error messages for panic=immediate-abort
26+
all(not(target_vendor = "uwp"), not(panic = "immediate-abort")) => {
2627
pub mod stack_overflow;
2728
}
2829
_ => {

0 commit comments

Comments
(0)

AltStyle によって変換されたページ (->オリジナル) /