From: Andy Lutomirski <luto@kernel.org>
To: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mark Rutland <mark.rutland@arm.com>,
Will Deacon <will.deacon@arm.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Andy Lutomirski <luto@kernel.org>,
Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>,
Peter Zijlstra <peterz@infradead.org>,
"linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
joeyli <jlee@suse.com>, Borislav Petkov <bp@alien8.de>,
"Michael S. Tsirkin" <mst@redhat.com>,
"Neri, Ricardo" <ricardo.neri@intel.com>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>
Subject: Re: [PATCH 3/3] x86/efi: Use efi_switch_mm() rather than manually twiddling with cr3
Date: Wed, 16 Aug 2017 09:14:41 -0700 [thread overview]
Message-ID: <CALCETrVSHuz=hcAgGxYHBmpiNcP4ECrJh885cR4X17QsJVj8+w@mail.gmail.com> (raw)
In-Reply-To: <20170816125715.GB3384@codeblueprint.co.uk>
On Wed, Aug 16, 2017 at 5:57 AM, Matt Fleming <matt@codeblueprint.co.uk> wrote:
> On Wed, 16 Aug, at 12:03:22PM, Mark Rutland wrote:
>>
>> I'd expect we'd abort at a higher level, not taking any sample. i.e.
>> we'd have the core overflow handler check in_funny_mm(), and if so, skip
>> the sample, as with the skid case.
>
> FYI, this is my preferred solution for x86 too.
One option for the "funny mm" flag would be literally the condition
current->mm != current->active_mm. I *think* this gets all the cases
right as long as efi_switch_mm is careful with its ordering and that
the arch switch_mm() code can handle the resulting ordering. (x86's
can now, I think, or at least will be able to in 4.14 -- not sure
about other arches).
That being said, there's a totally different solution: run EFI
callbacks in a kernel thread. This has other benefits: we could run
those callbacks in user mode some day, and doing *that* in a user
thread seems like a mistake.
--Andy
next prev parent reply other threads:[~2017-08-16 16:15 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-15 19:18 [PATCH 0/3] Use mm_struct and switch_mm() instead of manually Sai Praneeth Prakhya
2017-08-15 19:18 ` [PATCH 1/3] efi: Use efi_mm in x86 as well as ARM Sai Praneeth Prakhya
2017-08-15 19:18 ` [PATCH 2/3] x86/efi: Replace efi_pgd with efi_mm.pgd Sai Praneeth Prakhya
2017-08-15 19:18 ` [PATCH 3/3] x86/efi: Use efi_switch_mm() rather than manually twiddling with cr3 Sai Praneeth Prakhya
2017-08-15 21:46 ` Andy Lutomirski
2017-08-16 0:23 ` Sai Praneeth Prakhya
2017-08-16 0:47 ` Andy Lutomirski
2017-08-16 9:31 ` Ard Biesheuvel
2017-08-16 9:53 ` Mark Rutland
2017-08-16 10:07 ` Will Deacon
2017-08-16 11:03 ` Mark Rutland
2017-08-16 12:57 ` Matt Fleming
2017-08-16 16:14 ` Andy Lutomirski [this message]
2017-08-15 22:35 ` Mark Rutland
2017-08-17 10:35 ` Will Deacon
2017-08-17 15:52 ` Andy Lutomirski
2017-08-21 10:33 ` Peter Zijlstra
2017-08-21 13:56 ` Andy Lutomirski
2017-08-21 14:08 ` Peter Zijlstra
2017-08-21 15:23 ` Andy Lutomirski
2017-08-21 15:59 ` Peter Zijlstra
2017-08-21 16:08 ` Ard Biesheuvel
2017-08-23 22:52 ` Sai Praneeth Prakhya
2017-08-25 15:13 ` Andy Lutomirski
2017-08-21 17:24 ` Peter Zijlstra
2017-08-25 2:36 ` Sai Praneeth Prakhya
2017-08-25 15:13 ` Andy Lutomirski
2017-12-17 0:06 [PATCH 3/3] x86/efi: Use efi_switch_mm() rather than manually twiddling with %cr3 Sai Praneeth Prakhya
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