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Scan only the current thread's shadow stack. #11

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Merged
ltratt merged 1 commit into from
Mar 24, 2026
Merged

Scan only the current thread's shadow stack. #11

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17 changes: 4 additions & 13 deletions shared/runtime/gchelper_generic.c
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Original file line number Diff line number Diff line change
Expand Up @@ -206,12 +206,6 @@ static void gc_helper_get_regs(gc_helper_regs_t arr) {

#endif // MICROPY_GCREGS_SETJMP

#ifdef USE_YK
void gc_collect_shadowstack(void *start, void *end) {
gc_collect_root(start, ((intptr_t) end - (intptr_t) start) / sizeof(void *));
}
#endif

// Explicitly mark this as noinline to make sure the regs variable
// is effectively at the top of the stack: otherwise, in builds where
// LTO is enabled and a lot of inlining takes place we risk a stack
Expand All @@ -225,13 +219,10 @@ MP_NOINLINE void gc_helper_collect_regs_and_stack(void) {
gc_collect_root(regs_ptr, ((uintptr_t)MP_STATE_THREAD(stack_top) - (uintptr_t)&regs) / sizeof(uintptr_t));

#ifdef USE_YK
// Now scan the shadow stack.
//
// FIXME: this will scan the shadow stacks of *all* threads, but we should
// probably only scan the current thread's shadow stack here. yk doesn't
// currently have provide an API (e.g. a `yk_curthread_sstack_bounds()`)
// that could enable this.
yk_foreach_shadowstack(gc_collect_shadowstack);
// Now scan our thread's shadow stack.
void *start = NULL, *end = NULL;
yk_thread_shadowstack_bounds(&start, &end);
gc_collect_root((void **)start, ((intptr_t) end - (intptr_t) start) / sizeof(void *));
#endif
}

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