linux-kernel - Re: [GIT PULL] arm64 fixes for -rc5

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Date:   Fri, 6 Aug 2021 11:40:33 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Will Deacon <will@...nel.org>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Android Kernel Team <kernel-team@...roid.com>
Subject: Re: [GIT PULL] arm64 fixes for -rc5

On Fri, Aug 6, 2021 at 6:53 AM Will Deacon <will@...nel.org> wrote:
>
> Please pull these arm64 fixes for -rc5. It's all pretty minor but the
> main fix is sorting out how we deal with return values from 32-bit system
> calls as audit expects error codes to be sign-extended to 64 bits

I've pulled this, but that change looks _really_ odd.

First you seem to intentionally *zero-extend* the error value when you
actually set it in pt_regs, and then you sign-extend them when reading
them.

So the rules seem entirely arbitrary: oen place says "upper 32 bits
need to be clear" and another place says "upper 32 bits need to be
sign-extended".

Why this insanity? Why not make the rule be that the upper 32 bits are
always just sign-extended?

           Linus