linux-kernel - Re: [PATCH v1 8/8] x86/entry/clearregs: Clear registers for 32bit kernel

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Message-Id: <2C51FBC8-EB93-4003-9EB5-E3F94B1E05FA@amacapital.net>
Date:   Tue, 9 Jan 2018 17:24:36 -0800
From:   Andy Lutomirski <luto@...capital.net>
To:     Andi Kleen <andi@...stfloor.org>
Cc:     tglx@...utronix.de, x86@...nel.org, linux-kernel@...r.kernel.org,
        torvalds@...ux-foundation.org, dwmw@...zon.co.uk, pjt@...gle.com,
        luto@...nel.org, peterz@...radead.org, thomas.lendacky@....com,
        tim.c.chen@...ux.intel.com, gregkh@...ux-foundation.org,
        dave.hansen@...el.com, jikos@...nel.org,
        Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH v1 8/8] x86/entry/clearregs: Clear registers for 32bit kernel



> On Jan 9, 2018, at 5:03 PM, Andi Kleen <andi@...stfloor.org> wrote:
> 
> From: Andi Kleen <ak@...ux.intel.com>
> 
> On a 32bit kernel clearing registers is much simpler than
> on 64bit. The arguments for syscalls are initially passed
> to a C function through the stack, so there's no need
> to figure out how many arguments to clear.

Why are we even trying to improve the situation on 32-bit?  Unless someone actually tries to implement PTI, this seems useless.