Re: [PATCH 1/2] ppc64le live patch: clear out storage location(s) in mini stack frame

From: Balbir Singh
Date: Thu Mar 10 2016 - 22:37:47 EST

On 10/03/16 04:28, Torsten Duwe wrote:
> This can be applied on top of Petr Mladek's v4 rework of the ppc64le
> live patching. Inspired by Balbir Singh's v5, information about the
> callee's r2 is stored in a "reserved" 32 bit location in the caller's
> stack frame, instead of 64 bits in the newly created mini frame 24(r1).
> It only needs to work for a local call, when caller's TOC == callee's
> TOC, and along with the return address (LR) it's all within a 4GiB
> range (+-31 bits). If the original call already was global, we are
> allowed to restore any nonsense into r2, because the global caller
> will restore its TOC anyway from the ABI compliant location 24(r1)
> right after return.
Hi, Torsten

Sorry, I've had no time to test this. Caught up with something else for the moment.
Hopefully I'll get a chance over the weekend.

Have you tested this against Petr's sample changes to patch printk?

Balbir Singh.