1// SPDX-License-Identifier: GPL-2.0
2#include <linux/slab.h> /* for kmalloc */
3#include <linux/consolemap.h>
4#include <linux/interrupt.h>
5#include <linux/sched.h>
6#include <linux/device.h> /* for dev_warn */
7#include <linux/selection.h>
8#include <linux/workqueue.h>
9#include <linux/tty.h>
10#include <linux/tty_flip.h>
11#include <linux/atomic.h>
12#include <linux/console.h>
13
14#include "speakup.h"
15
16unsigned short spk_xs, spk_ys, spk_xe, spk_ye; /* our region points */
17struct vc_data *spk_sel_cons;
18
19struct speakup_selection_work {
20	struct work_struct work;
21	struct tiocl_selection sel;
22	struct tty_struct *tty;
23};
24
25static void __speakup_set_selection(struct work_struct *work)
26{
27	struct speakup_selection_work *ssw =
28		container_of(work, struct speakup_selection_work, work);
29
30	struct tty_struct *tty;
31	struct tiocl_selection sel;
32
33	sel = ssw->sel;
34
35	/* this ensures we copy sel before releasing the lock below */
36	rmb();
37
38	/* release the lock by setting tty of the struct to NULL */
39	tty = xchg(&ssw->tty, NULL);
40
41	if (spk_sel_cons != vc_cons[fg_console].d) {
42		spk_sel_cons = vc_cons[fg_console].d;
43		pr_warn("Selection: mark console not the same as cut\n");
44		goto unref;
45	}
46
47	console_lock();
48	clear_selection();
49	console_unlock();
50
51	set_selection_kernel(&sel, tty);
52
53unref:
54	tty_kref_put(tty);
55}
56
57static struct speakup_selection_work speakup_sel_work = {
58	.work = __WORK_INITIALIZER(speakup_sel_work.work,
59				   __speakup_set_selection)
60};
61
62int speakup_set_selection(struct tty_struct *tty)
63{
64	/* we get kref here first in order to avoid a subtle race when
65	 * cancelling selection work. getting kref first establishes the
66	 * invariant that if speakup_sel_work.tty is not NULL when
67	 * speakup_cancel_selection() is called, it must be the case that a put
68	 * kref is pending.
69	 */
70	tty_kref_get(tty);
71	if (cmpxchg(&speakup_sel_work.tty, NULL, tty)) {
72		tty_kref_put(tty);
73		return -EBUSY;
74	}
75	/* now we have the 'lock' by setting tty member of
76	 * speakup_selection_work. wmb() ensures that writes to
77	 * speakup_sel_work don't happen before cmpxchg() above.
78	 */
79	wmb();
80
81	speakup_sel_work.sel.xs = spk_xs + 1;
82	speakup_sel_work.sel.ys = spk_ys + 1;
83	speakup_sel_work.sel.xe = spk_xe + 1;
84	speakup_sel_work.sel.ye = spk_ye + 1;
85	speakup_sel_work.sel.sel_mode = TIOCL_SELCHAR;
86
87	schedule_work_on(WORK_CPU_UNBOUND, &speakup_sel_work.work);
88
89	return 0;
90}
91
92void speakup_cancel_selection(void)
93{
94	struct tty_struct *tty;
95
96	cancel_work_sync(&speakup_sel_work.work);
97	/* setting to null so that if work fails to run and we cancel it,
98	 * we can run it again without getting EBUSY forever from there on.
99	 * we need to use xchg here to avoid race with speakup_set_selection()
100	 */
101	tty = xchg(&speakup_sel_work.tty, NULL);
102	if (tty)
103		tty_kref_put(tty);
104}
105
106static void __speakup_paste_selection(struct work_struct *work)
107{
108	struct speakup_selection_work *ssw =
109		container_of(work, struct speakup_selection_work, work);
110	struct tty_struct *tty = xchg(&ssw->tty, NULL);
111
112	paste_selection(tty);
113	tty_kref_put(tty);
114}
115
116static struct speakup_selection_work speakup_paste_work = {
117	.work = __WORK_INITIALIZER(speakup_paste_work.work,
118				   __speakup_paste_selection)
119};
120
121int speakup_paste_selection(struct tty_struct *tty)
122{
123	tty_kref_get(tty);
124	if (cmpxchg(&speakup_paste_work.tty, NULL, tty)) {
125		tty_kref_put(tty);
126		return -EBUSY;
127	}
128
129	schedule_work_on(WORK_CPU_UNBOUND, &speakup_paste_work.work);
130	return 0;
131}
132
133void speakup_cancel_paste(void)
134{
135	struct tty_struct *tty;
136
137	cancel_work_sync(&speakup_paste_work.work);
138	tty = xchg(&speakup_paste_work.tty, NULL);
139	if (tty)
140		tty_kref_put(tty);
141}
142