86 lines
3.5 KiB
Diff
86 lines
3.5 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Peter Zijlstra <peterz@infradead.org>
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Date: Tue, 5 Dec 2017 13:34:54 +0100
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Subject: [PATCH] x86/doc: Remove obvious weirdnesses from the x86 MM layout
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documentation
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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CVE-2017-5754
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Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Cc: Andy Lutomirski <luto@kernel.org>
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Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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Cc: Borislav Petkov <bp@alien8.de>
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Cc: Brian Gerst <brgerst@gmail.com>
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Cc: Dave Hansen <dave.hansen@linux.intel.com>
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Cc: David Laight <David.Laight@aculab.com>
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Cc: Denys Vlasenko <dvlasenk@redhat.com>
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Cc: Eduardo Valentin <eduval@amazon.com>
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Cc: Greg KH <gregkh@linuxfoundation.org>
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Cc: H. Peter Anvin <hpa@zytor.com>
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Cc: Josh Poimboeuf <jpoimboe@redhat.com>
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Cc: Juergen Gross <jgross@suse.com>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Cc: Will Deacon <will.deacon@arm.com>
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Cc: aliguori@amazon.com
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Cc: daniel.gruss@iaik.tugraz.at
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Cc: hughd@google.com
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Cc: keescook@google.com
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Cc: linux-mm@kvack.org
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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(cherry picked from commit e8ffe96e5933d417195268478479933d56213a3f)
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Signed-off-by: Andy Whitcroft <apw@canonical.com>
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Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
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(cherry picked from commit d9012133906878a404cf47acc168ff9e4b10e379)
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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Documentation/x86/x86_64/mm.txt | 12 +++---------
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1 file changed, 3 insertions(+), 9 deletions(-)
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diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt
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index 83ca5a3b90ac..63a41671d25b 100644
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--- a/Documentation/x86/x86_64/mm.txt
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+++ b/Documentation/x86/x86_64/mm.txt
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@@ -1,6 +1,4 @@
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-<previous description obsolete, deleted>
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-
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Virtual memory map with 4 level page tables:
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0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm
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@@ -49,8 +47,9 @@ ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
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Architecture defines a 64-bit virtual address. Implementations can support
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less. Currently supported are 48- and 57-bit virtual addresses. Bits 63
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-through to the most-significant implemented bit are set to either all ones
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-or all zero. This causes hole between user space and kernel addresses.
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+through to the most-significant implemented bit are sign extended.
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+This causes hole between user space and kernel addresses if you interpret them
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+as unsigned.
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The direct mapping covers all memory in the system up to the highest
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memory address (this means in some cases it can also include PCI memory
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@@ -60,9 +59,6 @@ vmalloc space is lazily synchronized into the different PML4/PML5 pages of
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the processes using the page fault handler, with init_top_pgt as
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reference.
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-Current X86-64 implementations support up to 46 bits of address space (64 TB),
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-which is our current limit. This expands into MBZ space in the page tables.
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-
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We map EFI runtime services in the 'efi_pgd' PGD in a 64Gb large virtual
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memory window (this size is arbitrary, it can be raised later if needed).
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The mappings are not part of any other kernel PGD and are only available
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@@ -74,5 +70,3 @@ following fixmap section.
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Note that if CONFIG_RANDOMIZE_MEMORY is enabled, the direct mapping of all
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physical memory, vmalloc/ioremap space and virtual memory map are randomized.
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Their order is preserved but their base will be offset early at boot time.
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-
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--Andi Kleen, Jul 2004
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--
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2.14.2
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