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openbsd: don't reallocate a guard page on the stack. #102854

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Merged
merged 1 commit into from
Oct 13, 2022
Merged

openbsd: don't reallocate a guard page on the stack. #102854

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10 changes: 10 additions & 0 deletions library/std/src/sys/unix/thread.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -767,6 +767,16 @@ pub mod guard {
const GUARD_PAGES: usize = 1;
let guard = guardaddr..guardaddr + GUARD_PAGES * page_size;
Some(guard)
} else if cfg!(target_os = "openbsd") {
// OpenBSD stack already includes a guard page, and stack is
// immutable.
//
// We'll just note where we expect rlimit to start
// faulting, so our handler can report "stack overflow", and
// trust that the kernel's own stack guard will work.
let stackptr = get_stack_start_aligned()?;
let stackaddr = stackptr.addr();
Some(stackaddr - page_size..stackaddr)
} else {
// Reallocate the last page of the stack.
// This ensures SIGBUS will be raised on
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