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50da124a TG |
1 | /* |
2 | * Copyright(c) 2017 Intel Corporation. All rights reserved. | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of version 2 of the GNU General Public License as | |
6 | * published by the Free Software Foundation. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, but | |
9 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
11 | * General Public License for more details. | |
12 | * | |
13 | * This code is based in part on work published here: | |
14 | * | |
15 | * https://github.com/IAIK/KAISER | |
16 | * | |
17 | * The original work was written by and and signed off by for the Linux | |
18 | * kernel by: | |
19 | * | |
20 | * Signed-off-by: Richard Fellner <richard.fellner@student.tugraz.at> | |
21 | * Signed-off-by: Moritz Lipp <moritz.lipp@iaik.tugraz.at> | |
22 | * Signed-off-by: Daniel Gruss <daniel.gruss@iaik.tugraz.at> | |
23 | * Signed-off-by: Michael Schwarz <michael.schwarz@iaik.tugraz.at> | |
24 | * | |
25 | * Major changes to the original code by: Dave Hansen <dave.hansen@intel.com> | |
26 | * Mostly rewritten by Thomas Gleixner <tglx@linutronix.de> and | |
27 | * Andy Lutomirsky <luto@amacapital.net> | |
28 | */ | |
29 | #include <linux/kernel.h> | |
30 | #include <linux/errno.h> | |
31 | #include <linux/string.h> | |
32 | #include <linux/types.h> | |
33 | #include <linux/bug.h> | |
34 | #include <linux/init.h> | |
35 | #include <linux/spinlock.h> | |
36 | #include <linux/mm.h> | |
37 | #include <linux/uaccess.h> | |
38 | ||
39 | #include <asm/cpufeature.h> | |
40 | #include <asm/hypervisor.h> | |
41 | #include <asm/cmdline.h> | |
42 | #include <asm/pti.h> | |
43 | #include <asm/pgtable.h> | |
44 | #include <asm/pgalloc.h> | |
45 | #include <asm/tlbflush.h> | |
46 | #include <asm/desc.h> | |
47 | ||
48 | #undef pr_fmt | |
49 | #define pr_fmt(fmt) "Kernel/User page tables isolation: " fmt | |
50 | ||
51 | static void __init pti_print_if_insecure(const char *reason) | |
52 | { | |
53 | if (boot_cpu_has_bug(X86_BUG_CPU_INSECURE)) | |
54 | pr_info("%s\n", reason); | |
55 | } | |
56 | ||
96d3670f BP |
57 | static void __init pti_print_if_secure(const char *reason) |
58 | { | |
59 | if (!boot_cpu_has_bug(X86_BUG_CPU_INSECURE)) | |
60 | pr_info("%s\n", reason); | |
61 | } | |
62 | ||
50da124a TG |
63 | void __init pti_check_boottime_disable(void) |
64 | { | |
96d3670f BP |
65 | char arg[5]; |
66 | int ret; | |
67 | ||
50da124a TG |
68 | if (hypervisor_is_type(X86_HYPER_XEN_PV)) { |
69 | pti_print_if_insecure("disabled on XEN PV."); | |
70 | return; | |
71 | } | |
72 | ||
96d3670f BP |
73 | ret = cmdline_find_option(boot_command_line, "pti", arg, sizeof(arg)); |
74 | if (ret > 0) { | |
75 | if (ret == 3 && !strncmp(arg, "off", 3)) { | |
76 | pti_print_if_insecure("disabled on command line."); | |
77 | return; | |
78 | } | |
79 | if (ret == 2 && !strncmp(arg, "on", 2)) { | |
80 | pti_print_if_secure("force enabled on command line."); | |
81 | goto enable; | |
82 | } | |
83 | if (ret == 4 && !strncmp(arg, "auto", 4)) | |
84 | goto autosel; | |
85 | } | |
86 | ||
50da124a TG |
87 | if (cmdline_find_option_bool(boot_command_line, "nopti")) { |
88 | pti_print_if_insecure("disabled on command line."); | |
89 | return; | |
90 | } | |
91 | ||
96d3670f | 92 | autosel: |
50da124a TG |
93 | if (!boot_cpu_has_bug(X86_BUG_CPU_INSECURE)) |
94 | return; | |
96d3670f | 95 | enable: |
50da124a TG |
96 | setup_force_cpu_cap(X86_FEATURE_PTI); |
97 | } | |
98 | ||
99 | /* | |
100 | * Initialize kernel page table isolation | |
101 | */ | |
102 | void __init pti_init(void) | |
103 | { | |
104 | if (!static_cpu_has(X86_FEATURE_PTI)) | |
105 | return; | |
106 | ||
107 | pr_info("enabled\n"); | |
108 | } |