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
15void guarded_storage_release(struct task_struct *tsk)
16{
17	kfree(tsk->thread.gs_cb);
18	kfree(tsk->thread.gs_bc_cb);
19}
20
21static 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
39static 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
51static 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
67static 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
77void 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
94static 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
109SYSCALL_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