[OpenBIOS] [PATCH 2/4] ppc: add new context handler
Segher Boessenkool
segher at kernel.crashing.org
Wed May 4 21:07:06 CEST 2016
On Wed, May 04, 2016 at 07:54:03PM +0100, Mark Cave-Ayland wrote:
> > And the bl clobbers at least r4,r5.
>
> I'm sorry but I still don't understand? __switch_context loads a
> completely new CPU state from the stack in order to switch context so
> actually every single register gets clobbered. But we preserve the
> original link register in a local variable to ensure that we can jump
> back to where we were upon return.
If your asm clobbers all regs, the asm needs to say it does.
So this function clobbers all callee-save registers, but you want it
to return to the caller anyway? And that is expected to work?
Segher
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