linux-kernel - Re: [PATCHv3 6/8] x86/mm: Provide ARCH_GET_UNTAG_MASK and ARCH_ENABLE_TAGGED

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Message-ID: <20220610180445.fmzgrobscwrblxud@black.fi.intel.com>
Date:   Fri, 10 Jun 2022 21:04:45 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
Cc:     "peterz@...radead.org" <peterz@...radead.org>,
        "Lutomirski, Andy" <luto@...nel.org>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "hjl.tools@...il.com" <hjl.tools@...il.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "kcc@...gle.com" <kcc@...gle.com>,
        "andreyknvl@...il.com" <andreyknvl@...il.com>,
        "ak@...ux.intel.com" <ak@...ux.intel.com>,
        "dvyukov@...gle.com" <dvyukov@...gle.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "ryabinin.a.a@...il.com" <ryabinin.a.a@...il.com>,
        "glider@...gle.com" <glider@...gle.com>
Subject: Re: [PATCHv3 6/8] x86/mm: Provide ARCH_GET_UNTAG_MASK and
 ARCH_ENABLE_TAGGED_ADDR

On Fri, Jun 10, 2022 at 03:25:02PM +0000, Edgecombe, Rick P wrote:
> On Fri, 2022-06-10 at 17:35 +0300, Kirill A. Shutemov wrote:
> > +static int prctl_enable_tagged_addr(unsigned long nr_bits)
> > +{
> > +       struct mm_struct *mm = current->mm;
> 
> do_arch_prctl_64() can be called via ptrace. I think you need to
> operate on the mm of 'task', or just block the operation if task !=
> current.

Hm. True. Let's see if the interface in general good enough.

Ouch. I just noticied that I missed check for LAM feature :/

-- 
 Kirill A. Shutemov