From: David Laight <David.Laight@ACULAB.COM>
To: 'Linus Torvalds' <torvalds@linux-foundation.org>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>,
Andrew Cooper <andrew.cooper3@citrix.com>,
"x86@kernel.org" <x86@kernel.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>,
Peter Zijlstra <peterz@infradead.org>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Waiman Long <longman@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
Michael Ellerman <mpe@ellerman.id.au>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
Mark Rutland <mark.rutland@arm.com>
Subject: RE: [PATCH] x86/uaccess: Avoid barrier_nospec() in copy_from_user()
Date: Mon, 14 Oct 2024 14:40:20 +0000 [thread overview]
Message-ID: <83284833db3248deaf07b606457e3e8f@AcuMS.aculab.com> (raw)
In-Reply-To: <CAHk-=wgtwBkgKbvshy4AnW+2+5OYHCOuTDdtZBWwE42qfu79Uw@mail.gmail.com>
From: Linus Torvalds
> Sent: 14 October 2024 12:21
>
> On Mon, 14 Oct 2024 at 02:59, David Laight <David.Laight@aculab.com> wrote:
> >
> > Isn't LAM just plain stupid unless the hardware validates the bits
> > against the TLB?
>
> What? No. You can't do that. At some point, the TLB isn't filled, and
> then you have to do the access with lots of linear address bits
> masked.
And the 'high' bits get reloaded from the PTE.
(Although I suspect there isn't space for them.)
Reloading the high bits from the VA that caused the fault would
be 'interesting' - certainly better than just ignoring them.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2024-10-14 14:41 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-12 4:09 [PATCH] x86/uaccess: Avoid barrier_nospec() in copy_from_user() Josh Poimboeuf
2024-10-12 8:48 ` Andrew Cooper
2024-10-12 14:09 ` Josh Poimboeuf
2024-10-12 14:21 ` Borislav Petkov
2024-10-12 15:58 ` Linus Torvalds
2024-10-12 14:26 ` Andrew Cooper
2024-10-12 15:44 ` Linus Torvalds
2024-10-12 17:23 ` Andrew Cooper
2024-10-12 17:44 ` Linus Torvalds
2024-10-13 0:53 ` Linus Torvalds
2024-10-13 1:21 ` Linus Torvalds
2024-10-14 3:54 ` Josh Poimboeuf
2024-10-14 6:50 ` Linus Torvalds
2024-10-14 9:59 ` David Laight
2024-10-14 11:20 ` Linus Torvalds
2024-10-14 14:40 ` David Laight [this message]
2024-10-14 11:12 ` Andrew Cooper
2024-10-14 12:30 ` Kirill A. Shutemov
2024-10-14 15:39 ` Andrew Cooper
2024-10-15 10:00 ` Borislav Petkov
2024-10-20 22:44 ` Josh Poimboeuf
2024-10-20 22:59 ` Linus Torvalds
2024-10-20 23:11 ` Josh Poimboeuf
2024-10-20 23:14 ` Josh Poimboeuf
2024-10-20 23:35 ` Linus Torvalds
2024-10-23 9:44 ` Borislav Petkov
2024-10-23 19:17 ` Linus Torvalds
2024-10-23 20:07 ` Linus Torvalds
2024-10-23 23:32 ` Linus Torvalds
2024-10-24 2:00 ` Linus Torvalds
2024-10-24 9:21 ` David Laight
2024-10-24 16:53 ` Linus Torvalds
2024-10-25 8:56 ` David Laight
2024-10-25 16:35 ` Linus Torvalds
2024-10-21 10:48 ` Kirill A. Shutemov
2024-10-22 2:36 ` Linus Torvalds
2024-10-22 10:33 ` Kirill A. Shutemov
2024-10-22 8:16 ` Pawan Gupta
2024-10-22 10:44 ` Kirill A. Shutemov
2024-10-14 16:55 ` Linus Torvalds
2024-10-16 16:10 ` Linus Torvalds
2024-10-16 22:02 ` Andrew Cooper
2024-10-16 22:13 ` Kirill A. Shutemov
2024-10-16 22:34 ` Linus Torvalds
2024-10-28 11:29 ` Kirill A. Shutemov
2024-10-28 18:44 ` Linus Torvalds
2024-10-28 20:31 ` Kirill A. Shutemov
2024-10-28 20:49 ` Linus Torvalds
2024-10-16 22:32 ` Linus Torvalds
2024-10-17 11:00 ` Borislav Petkov
2024-10-14 11:56 ` Kirill A. Shutemov
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