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From:   Jann Horn <jannh@google.com>
Date:   Sat, 1 Oct 2022 01:02:25 +0200
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Subject: Re: [PATCH v2 22/39] mm: Don't allow write GUPs to shadow stack memory
To:     Dave Hansen <dave.hansen@intel.com>
Cc:     Rick Edgecombe <rick.p.edgecombe@intel.com>, x86@kernel.org,
        "H . Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
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On Sat, Oct 1, 2022 at 1:00 AM Jann Horn <jannh@google.com> wrote:
> So I think this change is actually a no-op - the only thing it does is
> to return 0 if write==1, !_PAGE_RW, and _PAGE_DIRTY. But the check
> below will always return 0 if !_PAGE_RW, unless I'm misreading it?

Er, to be precise, it will always return 0 if write==1 and !_PAGE_RW.