Re: [Qemu-devel] [PATCH] linux-user: ppc64: don't use volatile register during safe_syscall

[Shivaprasad G Bhat]

On 07/26/2018 10:56 PM, Richard Henderson wrote:
> On 07/25/2018 11:48 PM, Shivaprasad G Bhat wrote:
> > Reference:
> > https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html#REG
> This document is for _CALL_ELF < 2.  For ppc64le, the document is at
>
> https://openpowerfoundation.org/wp-content/uploads/2016/03/ABI64BitOpenPOWERv1.1_16July2015_pub4.pdf
>
> In both cases, it appears that we can (ab)use SP+16 to save
> the value of r14 across the syscall.  This slot would normally
> be used for saving our own return address (LR), but we have no
> need to save that value because it *is* preserved across the syscall.
I will send updated patch as suggested.

Thanks,
Shivaprasad
> r~