From: Linus Torvalds <torvalds@linux-foundation.org>
To: Peter Anvin <hpa@zytor.com>
Cc: Nadav Amit <nadav.amit@gmail.com>, Joerg Roedel <joro@8bytes.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
"the arch/x86 maintainers" <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@intel.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Juergen Gross <jgross@suse.com>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>, Jiri Kosina <jkosina@suse.cz>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Brian Gerst <brgerst@gmail.com>,
David Laight <David.Laight@aculab.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
Eduardo Valentin <eduval@amazon.com>,
Greg KH <gregkh@linuxfoundation.org>,
Will Deacon <will.deacon@arm.com>,
"Liguori, Anthony" <aliguori@amazon.com>,
Daniel Gruss <daniel.gruss@iaik.tugraz.at>,
Hugh Dickins <hughd@google.com>, Kees Cook <keescook@google.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Waiman Long <llong@redhat.com>, Joerg Roedel <jroedel@suse.de>
Subject: Re: [RFC PATCH 00/16] PTI support for x86-32
Date: Mon, 22 Jan 2018 12:14:03 -0800 [thread overview]
Message-ID: <CA+55aFxg5H38Ef4DUgMQ7KrsUtWdaKYKCRFZ8rangUrZ=OgCEw@mail.gmail.com> (raw)
In-Reply-To: <143DE376-A8A4-4A91-B4FF-E258D578242D@zytor.com>
On Sun, Jan 21, 2018 at 6:20 PM, <hpa@zytor.com> wrote:
>
> No idea about Intel, but at least on Transmeta CPUs the limit check was asynchronous with the access.
Yes, but TMTA had a really odd uarch and didn't check segment limits natively.
When you do it in hardware. the limit check is actually fairly natural
to do early rather than late (since it acts on the linear address
_before_ base add and TLB lookup).
So it's not like it can't be done late, but there are reasons why a
traditional microarchitecture might always end up doing the limit
check early and so segmentation might be a good defense against
meltdown on 32-bit Intel.
Linus
WARNING: multiple messages have this Message-ID (diff)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Peter Anvin <hpa@zytor.com>
Cc: Nadav Amit <nadav.amit@gmail.com>, Joerg Roedel <joro@8bytes.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@intel.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Juergen Gross <jgross@suse.com>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>, Jiri Kosina <jkosina@suse.cz>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Brian Gerst <brgerst@gmail.com>,
David Laight <David.Laight@aculab.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
Eduardo Valentin <eduval@amazon.com>,
Greg KH <gregkh@linuxfoundation.org>,
Will Deacon <will.deacon@arm.com>,
"Liguori, Anthony" <aliguori@amazon.com>,
Daniel Gruss <daniel.gruss@iaik.tugraz.at>,
Hugh Dickins <hughd@google.com>, Kees Cook <keescook@google.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Waiman Long <llong@redhat.com>, Joerg Roedel <jroedel@suse.de>
Subject: Re: [RFC PATCH 00/16] PTI support for x86-32
Date: Mon, 22 Jan 2018 12:14:03 -0800 [thread overview]
Message-ID: <CA+55aFxg5H38Ef4DUgMQ7KrsUtWdaKYKCRFZ8rangUrZ=OgCEw@mail.gmail.com> (raw)
In-Reply-To: <143DE376-A8A4-4A91-B4FF-E258D578242D@zytor.com>
On Sun, Jan 21, 2018 at 6:20 PM, <hpa@zytor.com> wrote:
>
> No idea about Intel, but at least on Transmeta CPUs the limit check was asynchronous with the access.
Yes, but TMTA had a really odd uarch and didn't check segment limits natively.
When you do it in hardware. the limit check is actually fairly natural
to do early rather than late (since it acts on the linear address
_before_ base add and TLB lookup).
So it's not like it can't be done late, but there are reasons why a
traditional microarchitecture might always end up doing the limit
check early and so segmentation might be a good defense against
meltdown on 32-bit Intel.
Linus
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next prev parent reply other threads:[~2018-01-22 20:14 UTC|newest]
Thread overview: 183+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-16 16:36 [RFC PATCH 00/16] PTI support for x86-32 Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-16 16:36 ` [PATCH 01/16] x86/entry/32: Rename TSS_sysenter_sp0 to TSS_sysenter_stack Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-16 18:35 ` Thomas Gleixner
2018-01-16 18:35 ` Thomas Gleixner
2018-01-16 16:36 ` [PATCH 02/16] x86/entry/32: Enter the kernel via trampoline stack Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-16 20:30 ` Thomas Gleixner
2018-01-16 20:30 ` Thomas Gleixner
2018-01-16 22:37 ` Andy Lutomirski
2018-01-16 22:37 ` Andy Lutomirski
2018-01-16 22:45 ` Andy Lutomirski
2018-01-16 22:45 ` Andy Lutomirski
2018-01-17 9:18 ` Joerg Roedel
2018-01-17 9:18 ` Joerg Roedel
2018-01-17 18:10 ` Andy Lutomirski
2018-01-17 18:10 ` Andy Lutomirski
2018-01-19 9:55 ` Joerg Roedel
2018-01-19 9:55 ` Joerg Roedel
2018-01-19 16:30 ` Andy Lutomirski
2018-01-19 16:30 ` Andy Lutomirski
2018-01-22 10:11 ` Joerg Roedel
2018-01-22 10:11 ` Joerg Roedel
2018-01-22 17:46 ` Andy Lutomirski
2018-01-22 17:46 ` Andy Lutomirski
2018-01-17 2:47 ` Boris Ostrovsky
2018-01-17 2:47 ` Boris Ostrovsky
2018-01-17 9:02 ` Joerg Roedel
2018-01-17 9:02 ` Joerg Roedel
2018-01-17 14:04 ` Andrew Cooper
2018-01-17 14:04 ` Andrew Cooper
2018-01-17 15:22 ` Boris Ostrovsky
2018-01-17 15:22 ` Boris Ostrovsky
2018-01-16 16:36 ` [PATCH 03/16] x86/entry/32: Leave the kernel via the " Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-16 22:48 ` Andy Lutomirski
2018-01-16 22:48 ` Andy Lutomirski
2018-01-17 9:24 ` Joerg Roedel
2018-01-17 9:24 ` Joerg Roedel
2018-01-17 13:57 ` Brian Gerst
2018-01-17 13:57 ` Brian Gerst
2018-01-17 14:00 ` Brian Gerst
2018-01-17 14:00 ` Brian Gerst
2018-01-17 14:14 ` Joerg Roedel
2018-01-17 14:14 ` Joerg Roedel
2018-01-17 14:45 ` Josh Poimboeuf
2018-01-17 14:45 ` Josh Poimboeuf
2018-01-17 14:10 ` Joerg Roedel
2018-01-17 14:10 ` Joerg Roedel
2018-01-17 18:12 ` Andy Lutomirski
2018-01-17 18:12 ` Andy Lutomirski
2018-01-19 9:57 ` Joerg Roedel
2018-01-19 9:57 ` Joerg Roedel
2018-01-16 16:36 ` [PATCH 04/16] x86/pti: Define X86_CR3_PTI_PCID_USER_BIT on x86_32 Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-16 22:46 ` Andy Lutomirski
2018-01-16 22:46 ` Andy Lutomirski
2018-01-17 9:26 ` Joerg Roedel
2018-01-17 9:26 ` Joerg Roedel
2018-01-16 16:36 ` [PATCH 05/16] x86/pgtable: Move pgdp kernel/user conversion functions to pgtable.h Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-16 16:36 ` [PATCH 06/16] x86/mm/ldt: Reserve high address-space range for the LDT Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-16 16:52 ` Peter Zijlstra
2018-01-16 16:52 ` Peter Zijlstra
2018-01-16 17:13 ` Joerg Roedel
2018-01-16 17:13 ` Joerg Roedel
2018-01-16 17:31 ` Peter Zijlstra
2018-01-16 17:31 ` Peter Zijlstra
2018-01-16 17:34 ` Waiman Long
2018-01-16 17:34 ` Waiman Long
2018-01-16 22:51 ` Andy Lutomirski
2018-01-16 22:51 ` Andy Lutomirski
2018-01-17 7:59 ` Peter Zijlstra
2018-01-17 7:59 ` Peter Zijlstra
2018-01-16 16:36 ` [PATCH 07/16] x86/mm: Move two more functions from pgtable_64.h to pgtable.h Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-16 18:03 ` Dave Hansen
2018-01-16 18:03 ` Dave Hansen
2018-01-16 19:11 ` Joerg Roedel
2018-01-16 19:11 ` Joerg Roedel
2018-01-16 19:34 ` Thomas Gleixner
2018-01-16 19:34 ` Thomas Gleixner
2018-01-16 16:36 ` [PATCH 08/16] x86/pgtable/32: Allocate 8k page-tables when PTI is enabled Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-17 23:43 ` Andy Lutomirski
2018-01-17 23:43 ` Andy Lutomirski
2018-01-19 9:57 ` Joerg Roedel
2018-01-19 9:57 ` Joerg Roedel
2018-01-16 16:36 ` [PATCH 09/16] x86/mm/pti: Clone CPU_ENTRY_AREA on PMD level on x86_32 Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-16 21:03 ` Thomas Gleixner
2018-01-16 21:03 ` Thomas Gleixner
2018-01-16 16:36 ` [PATCH 10/16] x86/mm/pti: Populate valid user pud entries Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-16 18:06 ` Dave Hansen
2018-01-16 18:06 ` Dave Hansen
2018-01-16 19:41 ` Joerg Roedel
2018-01-16 19:41 ` Joerg Roedel
2018-01-16 21:06 ` Thomas Gleixner
2018-01-16 21:06 ` Thomas Gleixner
2018-01-16 16:36 ` [PATCH 11/16] x86/mm/pgtable: Move pti_set_user_pgd() to pgtable.h Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-16 16:36 ` [PATCH 12/16] x86/mm/pae: Populate the user page-table with user pgd's Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-16 18:11 ` Dave Hansen
2018-01-16 18:11 ` Dave Hansen
2018-01-16 19:44 ` Joerg Roedel
2018-01-16 19:44 ` Joerg Roedel
2018-01-16 21:10 ` Thomas Gleixner
2018-01-16 21:10 ` Thomas Gleixner
2018-01-16 21:15 ` Dave Hansen
2018-01-16 21:15 ` Dave Hansen
2018-01-16 16:36 ` [PATCH 13/16] x86/mm/pti: Add an overflow check to pti_clone_pmds() Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-16 16:36 ` [PATCH 14/16] x86/mm/legacy: Populate the user page-table with user pgd's Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-17 23:41 ` Andy Lutomirski
2018-01-17 23:41 ` Andy Lutomirski
2018-01-16 16:36 ` [PATCH 15/16] x86/entry/32: Switch between kernel and user cr3 on entry/exit Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-16 16:36 ` [PATCH 16/16] x86/pti: Allow CONFIG_PAGE_TABLE_ISOLATION for x86_32 Joerg Roedel
2018-01-16 16:36 ` Joerg Roedel
2018-01-16 18:14 ` [RFC PATCH 00/16] PTI support for x86-32 Dave Hansen
2018-01-16 18:14 ` Dave Hansen
2018-01-16 19:46 ` Joerg Roedel
2018-01-16 19:46 ` Joerg Roedel
2018-01-16 18:59 ` Linus Torvalds
2018-01-16 18:59 ` Linus Torvalds
2018-01-16 19:02 ` Dave Hansen
2018-01-16 19:02 ` Dave Hansen
2018-01-16 19:21 ` Andrew Cooper
2018-01-16 19:21 ` Andrew Cooper
2018-01-16 19:55 ` Joerg Roedel
2018-01-16 19:55 ` Joerg Roedel
2018-01-16 21:20 ` Thomas Gleixner
2018-01-16 21:20 ` Thomas Gleixner
2018-01-17 9:55 ` Joerg Roedel
2018-01-17 9:55 ` Joerg Roedel
2018-01-16 22:26 ` Andy Lutomirski
2018-01-16 22:26 ` Andy Lutomirski
2018-01-17 9:33 ` Joerg Roedel
2018-01-17 9:33 ` Joerg Roedel
2018-01-19 10:55 ` Pavel Machek
2018-01-19 11:07 ` Joerg Roedel
2018-01-19 11:07 ` Joerg Roedel
2018-01-19 12:58 ` Pavel Machek
2018-01-21 20:13 ` Nadav Amit
2018-01-21 20:13 ` Nadav Amit
2018-01-21 20:44 ` Nadav Amit
2018-01-21 20:44 ` Nadav Amit
2018-01-21 23:46 ` Nadav Amit
2018-01-21 23:46 ` Nadav Amit
2018-01-22 2:11 ` Linus Torvalds
2018-01-22 2:11 ` Linus Torvalds
2018-01-22 2:20 ` hpa
2018-01-22 2:20 ` hpa
2018-01-22 20:14 ` Linus Torvalds [this message]
2018-01-22 20:14 ` Linus Torvalds
2018-01-22 21:10 ` H. Peter Anvin
2018-01-22 21:10 ` H. Peter Anvin
2018-01-23 14:38 ` Alan Cox
2018-01-23 14:38 ` Alan Cox
2018-01-22 2:27 ` Nadav Amit
2018-01-22 2:27 ` Nadav Amit
2018-01-22 8:56 ` Joerg Roedel
2018-01-22 8:56 ` Joerg Roedel
2018-01-23 14:57 ` Alan Cox
2018-01-23 14:57 ` Alan Cox
2018-01-25 17:09 ` Alan Cox
2018-01-25 17:09 ` Alan Cox
2018-01-26 12:36 ` Joerg Roedel
2018-01-26 12:36 ` Joerg Roedel
2018-01-22 9:55 ` David Laight
2018-01-22 10:04 ` Joerg Roedel
2018-01-22 10:04 ` Joerg Roedel
2018-01-24 18:58 ` Krzysztof Mazur
2018-01-24 18:58 ` Krzysztof Mazur
2018-01-25 22:09 ` Nadav Amit
2018-01-25 22:09 ` Nadav Amit
2018-01-26 9:28 ` Krzysztof Mazur
2018-01-26 9:28 ` Krzysztof Mazur
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