Re: [PATCH 03/18] arm64: hyp-stub: Move elx_sync into the vectors

On Tue, Jun 1, 2021 at 9:18 PM Pavel Tatashin [off-list ref] wrote:

quoted

quoted

It cannot call mutate_to_vhe because #HVC_VHE_RESTART is not used
here. But, if it had to it would not work as we cannot return to the
old kernel text after relocation.

OK, so you are happy with having a dangling branch pointing to
nowhere? Something in me screams that it isn't a good idea, in
general.

If HVC_SOFT_RESTART is all you need, I'd rather you have a small stub
that implements exactly that and nothing else. Feel free to extract it
as a reusable macro if you want.

Using macro won't help here to save kernel text. Optimally, we would
want to use only one vector table to reduce kernel text memory usage.
I could do that by overwriting sync entries in
trans_pgd_copy_el2_vectors(). But, that would be ugly, as I would need
to have some specific assumptions about what entries need to be
overwritten. Therefore, I decided to move the vector table that we
currently have in hibernate code, and make it common between kexec and
hibernate; trans_pgd_copy_el2_vectors() will use that table's body to
create copies.

Thanks,
Pasha

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