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Mark fiber stacks in rb_execution_context_mark

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Currently, fiber stacks are marked separately from the rest of the
execution context. The fiber code deliberately does _NOT_ set
ec->machine.stack_end on the saved EC, so that the code in
`rb_execution_context_mark` does not mark it; instead, the stack marking
is done in `cont_mark`.

Instead, we can set ec->machine.stack_end, and skip out on doing the
stack marking separately in `cont_mark`; that way, all machine stack
marking shares the same code (which does the nescessary ASAN things).

[Bug #20310]
This commit is contained in:
KJ Tsanaktsidis 2024-02-28 14:37:25 +11:00
parent 2535a09e85
commit 69579ed57a
1 changed files with 7 additions and 10 deletions
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17
cont.c
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@ -796,6 +796,9 @@ static inline void
ec_switch(rb_thread_t *th, rb_fiber_t *fiber)
{
rb_execution_context_t *ec = &fiber->cont.saved_ec;
#ifdef RUBY_ASAN_ENABLED
ec->machine.asan_fake_stack_handle = asan_get_thread_fake_stack_handle();
#endif
rb_ractor_set_current_ec(th->ractor, th->ec = ec);
// ruby_current_execution_context_ptr = th->ec = ec;
@ -1023,13 +1026,8 @@ cont_mark(void *ptr)
cont->machine.stack + cont->machine.stack_size);
}
else {
/* fiber */
const rb_fiber_t *fiber = (rb_fiber_t*)cont;
if (!FIBER_TERMINATED_P(fiber)) {
rb_gc_mark_locations(cont->machine.stack,
cont->machine.stack + cont->machine.stack_size);
}
/* fiber machine context is marked as part of rb_execution_context_mark, no need to
* do anything here. */
}
}
@ -1568,11 +1566,10 @@ fiber_setcontext(rb_fiber_t *new_fiber, rb_fiber_t *old_fiber)
}
}
/* exchange machine_stack_start between old_fiber and new_fiber */
/* these values are used in rb_gc_mark_machine_context to mark the fiber's stack. */
old_fiber->cont.saved_ec.machine.stack_start = th->ec->machine.stack_start;
old_fiber->cont.saved_ec.machine.stack_end = FIBER_TERMINATED_P(old_fiber) ? NULL : th->ec->machine.stack_end;
/* old_fiber->machine.stack_end should be NULL */
old_fiber->cont.saved_ec.machine.stack_end = NULL;
// if (DEBUG) fprintf(stderr, "fiber_setcontext: %p[%p] -> %p[%p]\n", (void*)old_fiber, old_fiber->stack.base, (void*)new_fiber, new_fiber->stack.base);