From: Dave Hansen <dave.hansen@intel.com>
To: Alexander Potapenko <glider@google.com>
Cc: Ingo Molnar <mingo@kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Linux Memory Management List <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Matthias Kaehlcke <mka@chromium.org>,
Dmitriy Vyukov <dvyukov@google.com>,
Michael Davidson <md@google.com>
Subject: Re: [PATCH] x86/boot/64/clang: Use fixup_pointer() to access '__supported_pte_mask'
Date: Tue, 8 May 2018 09:25:01 -0700 [thread overview]
Message-ID: <d149aae8-6aba-bb31-ddd6-49244598a617@intel.com> (raw)
In-Reply-To: <CAG_fn=Xv74c80swzFjKyybQpRj7Qj9K1NVH-D6gcxcYEoUJ1xA@mail.gmail.com>
On 05/08/2018 07:50 AM, Alexander Potapenko wrote:
>>> Similarly to commit 187e91fe5e91
>>> ("x86/boot/64/clang: Use fixup_pointer() to access 'next_early_pgt'"),
>>> '__supported_pte_mask' must be also accessed using fixup_pointer() to
>>> avoid position-dependent relocations.
>>>
>>> Signed-off-by: Alexander Potapenko <glider@google.com>
>>> Fixes: fb43d6cb91ef ("x86/mm: Do not auto-massage page protections")
>
>> In the interests of standalone changelogs, I'd really appreciate an
>> actual explanation of what's going on here. Your patch makes the code
>> uglier and doesn't fix anything functional from what I can see.
> You're right, sure. I'll send a patch with an updated description.
Great, thanks!
>> Do we have anything we can do to keep us from recreating these kinds of
>> regressions all the time?
> I'm not really aware of the possible options in the kernel land. Looks like
> a task for some objtool-like utility?
> As long as these regressions are caught with Clang, setting up a 0day Clang
> builder might help.
I've asked the 0day folks if this is doable. It would be great to see
it added.
prev parent reply other threads:[~2018-05-08 16:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-08 12:16 Alexander Potapenko
2018-05-08 14:30 ` Dave Hansen
2018-05-08 14:50 ` Alexander Potapenko
2018-05-08 16:25 ` Dave Hansen [this message]
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