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From: Andy Lutomirski <luto@kernel.org>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>,
	David Laight <David.Laight@aculab.com>,
	Kees Cook <keescook@chromium.org>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH PTI v3 03/10] x86/pti/64: Fix ESPFIX64 user mapping
Date: Thu, 14 Dec 2017 08:18:27 -0800	[thread overview]
Message-ID: <CALCETrUwfVOFMpU+YN0BKkmToOHC9+02QbLWP+h7mQvHATYd=Q@mail.gmail.com> (raw)
In-Reply-To: <20171214141038.7bddwvkabuy6ikxm@node.shutemov.name>

On Thu, Dec 14, 2017 at 6:10 AM, Kirill A. Shutemov
<kirill@shutemov.name> wrote:
> On Wed, Dec 13, 2017 at 09:01:50AM -0800, Andy Lutomirski wrote:
>> On Wed, Dec 13, 2017 at 5:12 AM, Kirill A. Shutemov
>> <kirill@shutemov.name> wrote:
>> > On Tue, Dec 12, 2017 at 07:56:38AM -0800, Andy Lutomirski wrote:
>> >> The ESPFIX64 user mapping belongs in pti.c just like all the other
>> >> user mappings.  Move it there and make it work correctly while we're
>> >> at it.
>> >>
>> >> Signed-off-by: Andy Lutomirski <luto@kernel.org>
>> >
>> > Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
>> >
>> > BTW, why do we open-code p?d_alloc() in pti_user_pagetable_walk_*()?
>> > It seems unnecessary and potentially bogus: see smp_wmb() in __p?d_alloc()
>> > helpers.
>>
>> The helpers won't work -- we're allocating kernel-owned tables in the
>> usermode part of init_mm.  The p?d_alloc() helpers allocate
>> user-accounted tables in the kernelmode part of the mm.
>
> What's wrong to account them against init_mm?
>

Nothing.  But the other parts are showstoppers: the helpers won't set
_PAGE_USER in the higher level entries and they will put the pgds in
the wrong place.

  reply	other threads:[~2017-12-14 16:18 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-11 23:40 [PATCH PTI v3 00/10] Clean up pgd handling and fix VSYSCALL and LDT Andy Lutomirski
2017-12-12 10:09 ` Ingo Molnar
2017-12-12 15:58   ` Andy Lutomirski
2017-12-12 16:13     ` Borislav Petkov
2017-12-12 16:14       ` Juergen Gross
2017-12-12 16:20         ` Borislav Petkov
2017-12-12 15:56 ` [PATCH PTI v3 01/10] x86/espfix/64: Fix espfix double-fault handling on 5-level systems Andy Lutomirski
2017-12-12 17:18   ` Kirill A. Shutemov
2017-12-15 18:34   ` [tip:x86/urgent] " tip-bot for Andy Lutomirski
2017-12-12 15:56 ` [PATCH PTI v3 02/10] x86/pti: Vastly simplify pgd synchronization Andy Lutomirski
2017-12-12 15:56 ` [PATCH PTI v3 03/10] x86/pti/64: Fix ESPFIX64 user mapping Andy Lutomirski
2017-12-13 13:12   ` Kirill A. Shutemov
2017-12-13 17:01     ` Andy Lutomirski
2017-12-14 14:10       ` Kirill A. Shutemov
2017-12-14 16:18         ` Andy Lutomirski [this message]
2017-12-12 15:56 ` [PATCH PTI v3 04/10] Revert "x86/mm/pti: Disable native VSYSCALL" Andy Lutomirski
2017-12-12 15:56 ` [PATCH PTI v3 05/10] x86/vsyscall/64: Explicitly set _PAGE_USER in the pagetable hierarchy Andy Lutomirski
2017-12-12 15:56 ` [PATCH PTI v3 06/10] x86/vsyscall/64: Warn and fail vsyscall emulation in NATIVE mode Andy Lutomirski
2017-12-12 15:56 ` [PATCH PTI v3 07/10] x86/pti: Map the vsyscall page if needed Andy Lutomirski
2017-12-12 15:56 ` [PATCH PTI v3 08/10] x86/mm/64: Improve the memory map documentation Andy Lutomirski
2017-12-12 15:56 ` [PATCH PTI v3 09/10] x86/mm/64: Make a full PGD-entry size hole in the memory map Andy Lutomirski
2017-12-13 13:17   ` Kirill A. Shutemov
2017-12-13 17:04     ` Andy Lutomirski
2017-12-12 15:56 ` [PATCH PTI v3 10/10] x86/pti: Put the LDT in its own PGD if PTI is on Andy Lutomirski
2017-12-15 22:54   ` Thomas Gleixner
2017-12-16  0:39   ` Thomas Gleixner
2017-12-16  6:41     ` Andy Lutomirski

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