[musl] Powerpc Linux 'scv' system call ABI proposal take 2

[Rich Felker]

On Wed, Apr 22, 2020 at 04:18:36PM +1000, Nicholas Piggin wrote:
> Yeah I had a bit of a play around with musl (which is very nice code I
> must say). The powerpc64 syscall asm is missing ctr clobber by the way.  
> Fortunately adding it doesn't change code generation for me, but it 
> should be fixed. glibc had the same bug at one point I think (probably 
> due to syscall ABI documentation not existing -- something now lives in 
> linux/Documentation/powerpc/syscall64-abi.rst).

Do you know anywhere I can read about the ctr issue, possibly the
relevant glibc bug report? I'm not particularly familiar with ppc
register file (at least I have to refamiliarize myself every time I
work on this stuff) so it'd be nice to understand what's
potentially-wrong now.

Rich