GNU Linux-libre 4.19.314-gnu1
[releases.git] / arch / s390 / kernel / guarded_storage.c
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                 __ctl_set_bit(2, 4);
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                 __ctl_clear_bit(2, 4);
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                 __ctl_set_bit(2, 4);
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 }