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(tsk->thread.gs_cb);
18 kfree(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(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(sibling, TIF_GUARDED_STORAGE))
103 kick_process(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(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
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.