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59d5af67 | 1 | From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 |
321d628a FG |
2 | From: Peter Zijlstra <peterz@infradead.org> |
3 | Date: Tue, 5 Dec 2017 13:34:54 +0100 | |
59d5af67 FG |
4 | Subject: [PATCH] x86/doc: Remove obvious weirdnesses from the x86 MM layout |
5 | documentation | |
321d628a FG |
6 | MIME-Version: 1.0 |
7 | Content-Type: text/plain; charset=UTF-8 | |
8 | Content-Transfer-Encoding: 8bit | |
9 | ||
10 | CVE-2017-5754 | |
11 | ||
12 | Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> | |
13 | Signed-off-by: Thomas Gleixner <tglx@linutronix.de> | |
14 | Cc: Andy Lutomirski <luto@kernel.org> | |
15 | Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> | |
16 | Cc: Borislav Petkov <bp@alien8.de> | |
17 | Cc: Brian Gerst <brgerst@gmail.com> | |
18 | Cc: Dave Hansen <dave.hansen@linux.intel.com> | |
19 | Cc: David Laight <David.Laight@aculab.com> | |
20 | Cc: Denys Vlasenko <dvlasenk@redhat.com> | |
21 | Cc: Eduardo Valentin <eduval@amazon.com> | |
22 | Cc: Greg KH <gregkh@linuxfoundation.org> | |
23 | Cc: H. Peter Anvin <hpa@zytor.com> | |
24 | Cc: Josh Poimboeuf <jpoimboe@redhat.com> | |
25 | Cc: Juergen Gross <jgross@suse.com> | |
26 | Cc: Linus Torvalds <torvalds@linux-foundation.org> | |
27 | Cc: Peter Zijlstra <peterz@infradead.org> | |
28 | Cc: Will Deacon <will.deacon@arm.com> | |
29 | Cc: aliguori@amazon.com | |
30 | Cc: daniel.gruss@iaik.tugraz.at | |
31 | Cc: hughd@google.com | |
32 | Cc: keescook@google.com | |
33 | Cc: linux-mm@kvack.org | |
34 | Signed-off-by: Ingo Molnar <mingo@kernel.org> | |
35 | (cherry picked from commit e8ffe96e5933d417195268478479933d56213a3f) | |
36 | Signed-off-by: Andy Whitcroft <apw@canonical.com> | |
37 | Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com> | |
38 | (cherry picked from commit d9012133906878a404cf47acc168ff9e4b10e379) | |
39 | Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com> | |
40 | --- | |
41 | Documentation/x86/x86_64/mm.txt | 12 +++--------- | |
42 | 1 file changed, 3 insertions(+), 9 deletions(-) | |
43 | ||
44 | diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt | |
45 | index 83ca5a3b90ac..63a41671d25b 100644 | |
46 | --- a/Documentation/x86/x86_64/mm.txt | |
47 | +++ b/Documentation/x86/x86_64/mm.txt | |
48 | @@ -1,6 +1,4 @@ | |
49 | ||
50 | -<previous description obsolete, deleted> | |
51 | - | |
52 | Virtual memory map with 4 level page tables: | |
53 | ||
54 | 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm | |
55 | @@ -49,8 +47,9 @@ ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole | |
56 | ||
57 | Architecture defines a 64-bit virtual address. Implementations can support | |
58 | less. Currently supported are 48- and 57-bit virtual addresses. Bits 63 | |
59 | -through to the most-significant implemented bit are set to either all ones | |
60 | -or all zero. This causes hole between user space and kernel addresses. | |
61 | +through to the most-significant implemented bit are sign extended. | |
62 | +This causes hole between user space and kernel addresses if you interpret them | |
63 | +as unsigned. | |
64 | ||
65 | The direct mapping covers all memory in the system up to the highest | |
66 | memory address (this means in some cases it can also include PCI memory | |
67 | @@ -60,9 +59,6 @@ vmalloc space is lazily synchronized into the different PML4/PML5 pages of | |
68 | the processes using the page fault handler, with init_top_pgt as | |
69 | reference. | |
70 | ||
71 | -Current X86-64 implementations support up to 46 bits of address space (64 TB), | |
72 | -which is our current limit. This expands into MBZ space in the page tables. | |
73 | - | |
74 | We map EFI runtime services in the 'efi_pgd' PGD in a 64Gb large virtual | |
75 | memory window (this size is arbitrary, it can be raised later if needed). | |
76 | The mappings are not part of any other kernel PGD and are only available | |
77 | @@ -74,5 +70,3 @@ following fixmap section. | |
78 | Note that if CONFIG_RANDOMIZE_MEMORY is enabled, the direct mapping of all | |
79 | physical memory, vmalloc/ioremap space and virtual memory map are randomized. | |
80 | Their order is preserved but their base will be offset early at boot time. | |
81 | - | |
82 | --Andi Kleen, Jul 2004 | |
83 | -- | |
84 | 2.14.2 | |
85 |