From: Dave Hansen <dave.hansen@linux.intel.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
moritz.lipp@iaik.tugraz.at,
Daniel Gruss <daniel.gruss@iaik.tugraz.at>,
michael.schwarz@iaik.tugraz.at,
richard.fellner@student.tugraz.at,
Linus Torvalds <torvalds@linux-foundation.org>,
Kees Cook <keescook@google.com>, Hugh Dickins <hughd@google.com>,
X86 ML <x86@kernel.org>
Subject: Re: [PATCH 24/30] x86, kaiser: disable native VSYSCALL
Date: Mon, 13 Nov 2017 13:07:03 -0800 [thread overview]
Message-ID: <8b23c090-f7c3-5110-011b-07e5131eb996@linux.intel.com> (raw)
In-Reply-To: <CALCETrWyagW0YV_-4xhiCxrxDBXTW7MBfZbSDbMY_mBYtsPRaA@mail.gmail.com>
On 11/12/2017 07:52 PM, Andy Lutomirski wrote:
> On Fri, Nov 10, 2017 at 3:04 PM, Dave Hansen
> <dave.hansen@linux.intel.com> wrote:
>> On 11/10/2017 02:06 PM, Andy Lutomirski wrote:
>>> I have nothing against disabling native. I object to breaking the
>>> weird binary tracing behavior in the emulation mode, especially if
>>> it's tangled up with KAISER. I got all kinds of flak in an earlier
>>> version of the vsyscall emulation patches when I broke that use case.
>>> KAISER may get very widely backported -- let's not make changes that
>>> are already known to break things.
>>
>> Is the thing that broke a "user mode program that actually looks at the
>> vsyscall page"? Like Linus is referring to here:
>>
> Yes. But I disagree with Linus. I think it would be perfectly
> reasonable to enable KAISER and to use a tool like pin on a legacy
> binary from some enterprise distribution. I bet there are lots of
> enterprise distributions that are still supported that use vsyscalls.
All we need to do in the end here is to re-set _PAGE_USER on the user
page table PGD that is used by the vsyscall page. We should be able to
do that with a line or two of code in kaiser_init(). We can do it
conditionally on when the VDSO is not compile-time disabled.
I can do this as a follow-on patch, or as the last one in the KAISER
series and leave it up to our esteemed maintainers to decide whether
they want to do it or not. Sound good?
Are there any userspace tests around that I can use for this, or will I
have to cook something up?
next prev parent reply other threads:[~2017-11-13 21:07 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-08 19:46 [PATCH 00/30] [v2] KAISER: unmap most of the kernel from userspace page tables Dave Hansen
2017-11-08 19:46 ` [PATCH 01/30] x86, mm: do not set _PAGE_USER for init_mm " Dave Hansen
2017-11-08 19:52 ` Linus Torvalds
2017-11-08 20:11 ` Dave Hansen
2017-11-09 10:29 ` Borislav Petkov
2017-11-08 19:46 ` [PATCH 02/30] x86, tlb: make CR4-based TLB flushes more robust Dave Hansen
2017-11-09 10:48 ` Borislav Petkov
2017-11-09 10:51 ` Thomas Gleixner
2017-11-09 11:02 ` Borislav Petkov
2017-11-08 19:46 ` [PATCH 03/30] x86, mm: document X86_CR4_PGE toggling behavior Dave Hansen
2017-11-09 12:21 ` Borislav Petkov
2017-11-08 19:46 ` [PATCH 04/30] x86, kaiser: disable global pages by default with KAISER Dave Hansen
2017-11-09 12:51 ` Borislav Petkov
2017-11-09 22:19 ` Thomas Gleixner
2017-11-08 19:46 ` [PATCH 05/30] x86, kaiser: prepare assembly for entry/exit CR3 switching Dave Hansen
2017-11-09 13:20 ` Borislav Petkov
2017-11-09 15:34 ` Dave Hansen
2017-11-09 15:59 ` Borislav Petkov
2017-11-08 19:46 ` [PATCH 06/30] x86, kaiser: introduce user-mapped percpu areas Dave Hansen
2017-11-08 19:46 ` [PATCH 07/30] x86, kaiser: mark percpu data structures required for entry/exit Dave Hansen
2017-11-08 19:47 ` [PATCH 08/30] x86, kaiser: unmap kernel from userspace page tables (core patch) Dave Hansen
2017-11-10 12:57 ` Ingo Molnar
2017-11-08 19:47 ` [PATCH 09/30] x86, kaiser: only populate shadow page tables for userspace Dave Hansen
2017-11-08 19:47 ` [PATCH 10/30] x86, kaiser: allow NX to be set in p4d/pgd Dave Hansen
2017-11-08 19:47 ` [PATCH 11/30] x86, kaiser: make sure static PGDs are 8k in size Dave Hansen
2017-11-08 19:47 ` [PATCH 12/30] x86, kaiser: map GDT into user page tables Dave Hansen
2017-11-08 19:47 ` [PATCH 13/30] x86, kaiser: map dynamically-allocated LDTs Dave Hansen
2017-11-08 19:47 ` [PATCH 14/30] x86, kaiser: map espfix structures Dave Hansen
2017-11-08 19:47 ` [PATCH 15/30] x86, kaiser: map entry stack variables Dave Hansen
2017-11-08 19:47 ` [PATCH 16/30] x86, kaiser: map trace interrupt entry Dave Hansen
2017-11-08 19:47 ` [PATCH 17/30] x86, kaiser: map debug IDT tables Dave Hansen
2017-11-08 19:47 ` [PATCH 18/30] x86, kaiser: map virtually-addressed performance monitoring buffers Dave Hansen
2017-11-10 12:17 ` Peter Zijlstra
2017-11-08 19:47 ` [PATCH 19/30] x86, mm: Move CR3 construction functions Dave Hansen
2017-11-08 19:47 ` [PATCH 20/30] x86, mm: remove hard-coded ASID limit checks Dave Hansen
2017-11-10 12:20 ` Peter Zijlstra
2017-11-10 18:41 ` Dave Hansen
2017-11-08 19:47 ` [PATCH 21/30] x86, mm: put mmu-to-h/w ASID translation in one place Dave Hansen
2017-11-08 19:47 ` [PATCH 22/30] x86, pcid, kaiser: allow flushing for future ASID switches Dave Hansen
2017-11-10 12:25 ` Peter Zijlstra
2017-11-08 19:47 ` [PATCH 23/30] x86, kaiser: use PCID feature to make user and kernel switches faster Dave Hansen
2017-11-08 19:47 ` [PATCH 24/30] x86, kaiser: disable native VSYSCALL Dave Hansen
2017-11-09 19:04 ` Andy Lutomirski
2017-11-09 19:26 ` Dave Hansen
2017-11-10 0:53 ` Andy Lutomirski
2017-11-10 0:57 ` Dave Hansen
2017-11-10 1:04 ` Andy Lutomirski
2017-11-10 1:22 ` Dave Hansen
2017-11-10 2:25 ` Andy Lutomirski
2017-11-10 6:31 ` Dave Hansen
2017-11-10 22:06 ` Andy Lutomirski
2017-11-10 23:04 ` Dave Hansen
2017-11-13 3:52 ` Andy Lutomirski
2017-11-13 21:07 ` Dave Hansen [this message]
2017-11-14 2:15 ` Andy Lutomirski
2017-11-08 19:47 ` [PATCH 25/30] x86, kaiser: add debugfs file to turn KAISER on/off at runtime Dave Hansen
2017-11-08 19:47 ` [PATCH 26/30] x86, kaiser: add a function to check for KAISER being enabled Dave Hansen
2017-11-08 19:47 ` [PATCH 27/30] x86, kaiser: un-poison PGDs at runtime Dave Hansen
2017-11-08 19:47 ` [PATCH 28/30] x86, kaiser: allow KAISER to be enabled/disabled " Dave Hansen
2017-11-08 19:47 ` [PATCH 29/30] x86, kaiser: add Kconfig Dave Hansen
2017-11-08 19:47 ` [PATCH 30/30] x86, kaiser, xen: Dynamically disable KAISER when running under Xen PV Dave Hansen
2017-11-09 15:01 ` Juergen Gross
2017-11-10 19:30 [PATCH 00/30] [v3] KAISER: unmap most of the kernel from userspace page tables Dave Hansen
2017-11-10 19:31 ` [PATCH 24/30] x86, kaiser: disable native VSYSCALL Dave Hansen
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