Re: CVS commit: src/sys/arch/aarch64

[maya%NetBSD.org@localhost]

On Sat, May 23, 2020 at 02:13:46PM -0700, Jason Thorpe wrote:
> 
> > On May 23, 2020, at 11:08 AM, Ryo Shimizu <ryo%netbsd.org@localhost> wrote:
> > 
> > Module Name:	src
> > Committed By:	ryo
> > Date:		Sat May 23 18:08:59 UTC 2020
> > 
> > Modified Files:
> > 	src/sys/arch/aarch64/aarch64: cpufunc.c cpuswitch.S exec_machdep.c
> > 	    genassym.cf netbsd32_machdep.c vectors.S vm_machdep.c
> > 	src/sys/arch/aarch64/include: armreg.h machdep.h proc.h
> > 
> > Log Message:
> > Not only the kernel thread, but also the userland PAC keys
> > (APIA,APIB,APDA,APDB,APGA) are now randomly initialized at exec, and switched
> > when context switch.
> > userland programs are able to perform pointer authentication on ARMv8.3+PAC cpu.
> 
> Has any consideration be given to perhaps creating a new MACHINE_ARCH for this, or somehow otherwise decorating the ELF files to indicate their exec-ability?

I am under the impression that PAC was designed to be forewards
compatible, so older CPUs can execute code with this annotation. I don't
whether it works in practice though.