[PATCH v6 1/6] arm64: kprobe: add checks for ARMv8.3-PAuth combined instructions

[Will Deacon]

On Tue, Sep 08, 2020 at 11:51:08AM +0100, Dave Martin wrote:
> On Mon, Sep 07, 2020 at 10:45:51PM +0100, Will Deacon wrote:
> > On Fri, Sep 04, 2020 at 04:12:04PM +0530, Amit Daniel Kachhap wrote:
> > > diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
> > > index 0bc46149e491..324234068fee 100644
> > > --- a/arch/arm64/include/asm/insn.h
> > > +++ b/arch/arm64/include/asm/insn.h
> > > @@ -359,9 +359,21 @@ __AARCH64_INSN_FUNCS(brk,	0xFFE0001F, 0xD4200000)
> > >  __AARCH64_INSN_FUNCS(exception,	0xFF000000, 0xD4000000)
> > >  __AARCH64_INSN_FUNCS(hint,	0xFFFFF01F, 0xD503201F)
> > >  __AARCH64_INSN_FUNCS(br,	0xFFFFFC1F, 0xD61F0000)
> > > +__AARCH64_INSN_FUNCS(braaz,	0xFFFFFC1F, 0xD61F081F)
> > > +__AARCH64_INSN_FUNCS(brabz,	0xFFFFFC1F, 0xD61F0C1F)
> > > +__AARCH64_INSN_FUNCS(braa,	0xFFFFFC00, 0xD71F0800)
> > > +__AARCH64_INSN_FUNCS(brab,	0xFFFFFC00, 0xD71F0C00)
> > 
> > When do we need to distinguish these variants? Can we modify the mask/value
> > pair so that we catch bra* in one go? That would match how they are
> > documented in the Arm ARM.
> > 
> > >  __AARCH64_INSN_FUNCS(blr,	0xFFFFFC1F, 0xD63F0000)
> > > +__AARCH64_INSN_FUNCS(blraaz,	0xFFFFFC1F, 0xD63F081F)
> > > +__AARCH64_INSN_FUNCS(blrabz,	0xFFFFFC1F, 0xD63F0C1F)
> > > +__AARCH64_INSN_FUNCS(blraa,	0xFFFFFC00, 0xD73F0800)
> > > +__AARCH64_INSN_FUNCS(blrab,	0xFFFFFC00, 0xD73F0C00)
> > 
> > Same here for blra*
> > 
> > >  __AARCH64_INSN_FUNCS(ret,	0xFFFFFC1F, 0xD65F0000)
> > > +__AARCH64_INSN_FUNCS(retaa,	0xFFFFFFFF, 0xD65F0BFF)
> > > +__AARCH64_INSN_FUNCS(retab,	0xFFFFFFFF, 0xD65F0FFF)
> > >  __AARCH64_INSN_FUNCS(eret,	0xFFFFFFFF, 0xD69F03E0)
> > > +__AARCH64_INSN_FUNCS(eretaa,	0xFFFFFFFF, 0xD69F0BFF)
> > > +__AARCH64_INSN_FUNCS(eretab,	0xFFFFFFFF, 0xD69F0FFF)
> > 
> > ... and here for ereta*.
> 
> From my side:
> 
> I thought about this myself, but I thought that this may be easier to
> maintain if we avoid lumping instructions together.

Maybe, but I'm just suggesting to lump them together in the same way as the
Arm ARM, which I think helps readability because it lines up directly with
the text.

> I guess I'm happy either way.

Ok, thanks. Amit -- can you repost the series with that change, please, and
I'll queue the lot for 5.10?

Thanks,

Will