mysterious native stack overflow check calculation

[yamt]

invoke_native_with_hw_bound_check and call_wasm_with_hw_bound_check have native stack overflow checks
against native_stack_boundary + page_size * (guard_page_count + 1).
i don't understand where this + 1 came from. @wenyongh do you remember?

[wenyongh]

invoke_native_with_hw_bound_check and call_wasm_with_hw_bound_check have native stack overflow checks against native_stack_boundary + page_size * (guard_page_count + 1). i don't understand where this + 1 came from. @wenyongh do you remember?

@yamt I remember that it is to reserve some stack space to ensure the runtime can successfully call to the AOT function, for example, avoiding core dump at os_setjmp, since wasm_exec_env_push_jmpbuf has been executed before it, if os_setjmp failed, then in the signal handler, the wrong jmpbuf will be popped for os_longjmp to jump. And we had better let stack overflow occurs in AOT code, not sure whether occurring in runtime part (e.g. wasm_runtime_invoke_native) will cause unexpected behavior.

[yamt]

invoke_native_with_hw_bound_check and call_wasm_with_hw_bound_check have native stack overflow checks against native_stack_boundary + page_size * (guard_page_count + 1). i don't understand where this + 1 came from. @wenyongh do you remember?

@yamt I remember that it is to reserve some stack space to ensure the runtime can successfully call to the AOT function, for example, avoiding core dump at os_setjmp, since wasm_exec_env_push_jmpbuf has been executed before it, if os_setjmp failed, then in the signal handler, the wrong jmpbuf will be popped for os_longjmp to jump.

it doesn't seem to make much sense to me because native_stack_boundary at this point already includes WASM_STACK_GUARD_SIZE adjustment, which should be enough for the jmpbuf setup.

And we had better let stack overflow occurs in AOT code, not sure whether occurring in runtime part (e.g. wasm_runtime_invoke_native) will cause unexpected behavior.

it makes sense.
i'm thinking to separate stack consumption of native functions from WASM_STACK_GUARD_SIZE.

[wenyongh]

Yes, after some amendings, the code may look a little confusing, please help enhance it if you are glad to.

[yamt]

fixed by #3351