1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Copyright IBM Corp. 2016 |
4 | * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com> |
5 | */ |
6 | |
7 | #include <linux/kernel.h> |
8 | #include <linux/syscalls.h> |
9 | #include <linux/signal.h> |
10 | #include <linux/mm.h> |
11 | #include <linux/slab.h> |
12 | #include <asm/guarded_storage.h> |
13 | #include "entry.h" |
14 | |
15 | void guarded_storage_release(struct task_struct *tsk) |
16 | { |
17 | kfree(objp: tsk->thread.gs_cb); |
18 | kfree(objp: tsk->thread.gs_bc_cb); |
19 | } |
20 | |
21 | static int gs_enable(void) |
22 | { |
23 | struct gs_cb *gs_cb; |
24 | |
25 | if (!current->thread.gs_cb) { |
26 | gs_cb = kzalloc(sizeof(*gs_cb), GFP_KERNEL); |
27 | if (!gs_cb) |
28 | return -ENOMEM; |
29 | gs_cb->gsd = 25; |
30 | preempt_disable(); |
31 | local_ctl_set_bit(2, CR2_GUARDED_STORAGE_BIT); |
32 | load_gs_cb(gs_cb); |
33 | current->thread.gs_cb = gs_cb; |
34 | preempt_enable(); |
35 | } |
36 | return 0; |
37 | } |
38 | |
39 | static int gs_disable(void) |
40 | { |
41 | if (current->thread.gs_cb) { |
42 | preempt_disable(); |
43 | kfree(current->thread.gs_cb); |
44 | current->thread.gs_cb = NULL; |
45 | local_ctl_clear_bit(2, CR2_GUARDED_STORAGE_BIT); |
46 | preempt_enable(); |
47 | } |
48 | return 0; |
49 | } |
50 | |
51 | static int gs_set_bc_cb(struct gs_cb __user *u_gs_cb) |
52 | { |
53 | struct gs_cb *gs_cb; |
54 | |
55 | gs_cb = current->thread.gs_bc_cb; |
56 | if (!gs_cb) { |
57 | gs_cb = kzalloc(sizeof(*gs_cb), GFP_KERNEL); |
58 | if (!gs_cb) |
59 | return -ENOMEM; |
60 | current->thread.gs_bc_cb = gs_cb; |
61 | } |
62 | if (copy_from_user(gs_cb, u_gs_cb, sizeof(*gs_cb))) |
63 | return -EFAULT; |
64 | return 0; |
65 | } |
66 | |
67 | static int gs_clear_bc_cb(void) |
68 | { |
69 | struct gs_cb *gs_cb; |
70 | |
71 | gs_cb = current->thread.gs_bc_cb; |
72 | current->thread.gs_bc_cb = NULL; |
73 | kfree(objp: gs_cb); |
74 | return 0; |
75 | } |
76 | |
77 | void gs_load_bc_cb(struct pt_regs *regs) |
78 | { |
79 | struct gs_cb *gs_cb; |
80 | |
81 | preempt_disable(); |
82 | clear_thread_flag(TIF_GUARDED_STORAGE); |
83 | gs_cb = current->thread.gs_bc_cb; |
84 | if (gs_cb) { |
85 | kfree(current->thread.gs_cb); |
86 | current->thread.gs_bc_cb = NULL; |
87 | local_ctl_set_bit(2, CR2_GUARDED_STORAGE_BIT); |
88 | load_gs_cb(gs_cb); |
89 | current->thread.gs_cb = gs_cb; |
90 | } |
91 | preempt_enable(); |
92 | } |
93 | |
94 | static int gs_broadcast(void) |
95 | { |
96 | struct task_struct *sibling; |
97 | |
98 | read_lock(&tasklist_lock); |
99 | for_each_thread(current, sibling) { |
100 | if (!sibling->thread.gs_bc_cb) |
101 | continue; |
102 | if (test_and_set_tsk_thread_flag(tsk: sibling, flag: TIF_GUARDED_STORAGE)) |
103 | kick_process(tsk: sibling); |
104 | } |
105 | read_unlock(&tasklist_lock); |
106 | return 0; |
107 | } |
108 | |
109 | SYSCALL_DEFINE2(s390_guarded_storage, int, command, |
110 | struct gs_cb __user *, gs_cb) |
111 | { |
112 | if (!MACHINE_HAS_GS) |
113 | return -EOPNOTSUPP; |
114 | switch (command) { |
115 | case GS_ENABLE: |
116 | return gs_enable(); |
117 | case GS_DISABLE: |
118 | return gs_disable(); |
119 | case GS_SET_BC_CB: |
120 | return gs_set_bc_cb(u_gs_cb: gs_cb); |
121 | case GS_CLEAR_BC_CB: |
122 | return gs_clear_bc_cb(); |
123 | case GS_BROADCAST: |
124 | return gs_broadcast(); |
125 | default: |
126 | return -EINVAL; |
127 | } |
128 | } |
129 | |