From: Andrew Morton <akpm@linux-foundation.org>
To: Steven Price <steven.price@arm.com>
Cc: Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
x86@kernel.org, Jan Beulich <jbeulich@suse.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 0/2] Fix W+X debug feature on x86
Date: Thu, 21 May 2020 12:08:43 -0700 [thread overview]
Message-ID: <20200521120843.427b7ff33f8ed7f824eb07f9@linux-foundation.org> (raw)
In-Reply-To: <20200521152308.33096-1-steven.price@arm.com>
On Thu, 21 May 2020 16:23:06 +0100 Steven Price <steven.price@arm.com> wrote:
> Jan alert me[1] that the W+X detection debug feature was broken in x86
> by my change[2] to switch x86 to use the generic ptdump infrastructure.
>
> Fundamentally the approach of trying to move the calculation of
> effective permissions into note_page() was broken because note_page() is
> only called for 'leaf' entries and the effective permissions are passed
> down via the internal nodes of the page tree. The solution I've taken
> here is to create a new (optional) callback which is called for all
> nodes of the page tree and therefore can calculate the effective
> permissions.
>
> Secondly on some configurations (32 bit with PAE) "unsigned long" is not
> large enough to store the table entries. The fix here is simple - let's
> just use a u64.
I assumed that a cc:stable was appropriate on both of these(?).
> I'd welcome testing (and other comments), especially if you have a
> configuration which previously triggered W+X warnings as I don't have
> such a setup.
I'll wait a while for such testing. If nothing happens then I guess we
merge it up and see what then happens.
next prev parent reply other threads:[~2020-05-21 19:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-21 15:23 [PATCH 0/2] Fix W+X debug feature on x86 Steven Price
2020-05-21 15:23 ` [PATCH 1/2] x86: mm: ptdump: Calculate effective permissions correctly Steven Price
2020-05-22 18:07 ` Qian Cai
2020-05-26 10:41 ` Steven Price
2020-05-27 15:15 ` Jan Beulich
2020-05-27 15:55 ` Steven Price
2020-05-21 15:23 ` [PATCH 2/2] mm: ptdump: Expand type of 'val' in note_page() Steven Price
2020-05-21 19:08 ` Andrew Morton [this message]
2020-05-22 12:50 ` [PATCH 0/2] Fix W+X debug feature on x86 Steven Price
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