arm64: straight-line speculation status

[Julien Thierry]

Hi,

I was wondering, what is the status of mitigations for the arm 
straight-line speculation[1] in linux?

It looks like some option was added to GCC to deal with branch and 
return instructions, however it doesn't look like there is a kernel 
config to use that compiler option.

Also, I would assume that BLR and RET instructions in assembly files 
would also need to be adapted.

Has this already been discussed? Are there any works in progress or 
plans associated with it?

[1] 
https://developer.arm.com/support/arm-security-updates/speculative-processor-vulnerability/frequently-asked-questions#SLS4

Thanks,

-- 
Julien Thierry