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59d5af67 | 1 | From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 |
321d628a FG |
2 | From: Andy Lutomirski <luto@kernel.org> |
3 | Date: Mon, 4 Dec 2017 15:07:45 +0100 | |
59d5af67 | 4 | Subject: [PATCH] x86/mm/pti: Share cpu_entry_area with user space page tables |
321d628a FG |
5 | MIME-Version: 1.0 |
6 | Content-Type: text/plain; charset=UTF-8 | |
7 | Content-Transfer-Encoding: 8bit | |
8 | ||
9 | CVE-2017-5754 | |
10 | ||
11 | Share the cpu entry area so the user space and kernel space page tables | |
12 | have the same P4D page. | |
13 | ||
14 | Signed-off-by: Andy Lutomirski <luto@kernel.org> | |
15 | Signed-off-by: Thomas Gleixner <tglx@linutronix.de> | |
16 | Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> | |
17 | Cc: Borislav Petkov <bp@alien8.de> | |
18 | Cc: Brian Gerst <brgerst@gmail.com> | |
19 | Cc: Dave Hansen <dave.hansen@linux.intel.com> | |
20 | Cc: David Laight <David.Laight@aculab.com> | |
21 | Cc: Denys Vlasenko <dvlasenk@redhat.com> | |
22 | Cc: Eduardo Valentin <eduval@amazon.com> | |
23 | Cc: Greg KH <gregkh@linuxfoundation.org> | |
24 | Cc: H. Peter Anvin <hpa@zytor.com> | |
25 | Cc: Josh Poimboeuf <jpoimboe@redhat.com> | |
26 | Cc: Juergen Gross <jgross@suse.com> | |
27 | Cc: Linus Torvalds <torvalds@linux-foundation.org> | |
28 | Cc: Peter Zijlstra <peterz@infradead.org> | |
29 | Cc: Will Deacon <will.deacon@arm.com> | |
30 | Cc: aliguori@amazon.com | |
31 | Cc: daniel.gruss@iaik.tugraz.at | |
32 | Cc: hughd@google.com | |
33 | Cc: keescook@google.com | |
34 | Signed-off-by: Ingo Molnar <mingo@kernel.org> | |
35 | (cherry picked from commit f7cfbee91559ca7e3e961a00ffac921208a115ad) | |
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 6e8142de3a6e84a82a421b66a74ba37976912282) | |
39 | Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com> | |
40 | --- | |
41 | arch/x86/mm/pti.c | 25 +++++++++++++++++++++++++ | |
42 | 1 file changed, 25 insertions(+) | |
43 | ||
44 | diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c | |
45 | index d58bcee470fc..59290356f19f 100644 | |
46 | --- a/arch/x86/mm/pti.c | |
47 | +++ b/arch/x86/mm/pti.c | |
48 | @@ -264,6 +264,29 @@ pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear) | |
49 | } | |
50 | } | |
51 | ||
52 | +/* | |
53 | + * Clone a single p4d (i.e. a top-level entry on 4-level systems and a | |
54 | + * next-level entry on 5-level systems. | |
55 | + */ | |
56 | +static void __init pti_clone_p4d(unsigned long addr) | |
57 | +{ | |
58 | + p4d_t *kernel_p4d, *user_p4d; | |
59 | + pgd_t *kernel_pgd; | |
60 | + | |
61 | + user_p4d = pti_user_pagetable_walk_p4d(addr); | |
62 | + kernel_pgd = pgd_offset_k(addr); | |
63 | + kernel_p4d = p4d_offset(kernel_pgd, addr); | |
64 | + *user_p4d = *kernel_p4d; | |
65 | +} | |
66 | + | |
67 | +/* | |
68 | + * Clone the CPU_ENTRY_AREA into the user space visible page table. | |
69 | + */ | |
70 | +static void __init pti_clone_user_shared(void) | |
71 | +{ | |
72 | + pti_clone_p4d(CPU_ENTRY_AREA_BASE); | |
73 | +} | |
74 | + | |
75 | /* | |
76 | * Initialize kernel page table isolation | |
77 | */ | |
78 | @@ -273,4 +296,6 @@ void __init pti_init(void) | |
79 | return; | |
80 | ||
81 | pr_info("enabled\n"); | |
82 | + | |
83 | + pti_clone_user_shared(); | |
84 | } | |
85 | -- | |
86 | 2.14.2 | |
87 |