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
16 unsigned short spk_xs, spk_ys, spk_xe, spk_ye; /* our region points */
17 struct vc_data *spk_sel_cons;
18
19 struct speakup_selection_work {
20 struct work_struct work;
21 struct tiocl_selection sel;
22 struct tty_struct *tty;
23 };
24
speakup_clear_selection(void)25 void speakup_clear_selection(void)
26 {
27 console_lock();
28 clear_selection();
29 console_unlock();
30 }
31
__speakup_set_selection(struct work_struct * work)32 static void __speakup_set_selection(struct work_struct *work)
33 {
34 struct speakup_selection_work *ssw =
35 container_of(work, struct speakup_selection_work, work);
36
37 struct tty_struct *tty;
38 struct tiocl_selection sel;
39
40 sel = ssw->sel;
41
42 /* this ensures we copy sel before releasing the lock below */
43 rmb();
44
45 /* release the lock by setting tty of the struct to NULL */
46 tty = xchg(&ssw->tty, NULL);
47
48 if (spk_sel_cons != vc_cons[fg_console].d) {
49 spk_sel_cons = vc_cons[fg_console].d;
50 pr_warn("Selection: mark console not the same as cut\n");
51 goto unref;
52 }
53
54 console_lock();
55 set_selection_kernel(&sel, tty);
56 console_unlock();
57
58 unref:
59 tty_kref_put(tty);
60 }
61
62 static struct speakup_selection_work speakup_sel_work = {
63 .work = __WORK_INITIALIZER(speakup_sel_work.work,
64 __speakup_set_selection)
65 };
66
speakup_set_selection(struct tty_struct * tty)67 int speakup_set_selection(struct tty_struct *tty)
68 {
69 /* we get kref here first in order to avoid a subtle race when
70 * cancelling selection work. getting kref first establishes the
71 * invariant that if speakup_sel_work.tty is not NULL when
72 * speakup_cancel_selection() is called, it must be the case that a put
73 * kref is pending.
74 */
75 tty_kref_get(tty);
76 if (cmpxchg(&speakup_sel_work.tty, NULL, tty)) {
77 tty_kref_put(tty);
78 return -EBUSY;
79 }
80 /* now we have the 'lock' by setting tty member of
81 * speakup_selection_work. wmb() ensures that writes to
82 * speakup_sel_work don't happen before cmpxchg() above.
83 */
84 wmb();
85
86 speakup_sel_work.sel.xs = spk_xs + 1;
87 speakup_sel_work.sel.ys = spk_ys + 1;
88 speakup_sel_work.sel.xe = spk_xe + 1;
89 speakup_sel_work.sel.ye = spk_ye + 1;
90 speakup_sel_work.sel.sel_mode = TIOCL_SELCHAR;
91
92 schedule_work_on(WORK_CPU_UNBOUND, &speakup_sel_work.work);
93
94 return 0;
95 }
96
speakup_cancel_selection(void)97 void speakup_cancel_selection(void)
98 {
99 struct tty_struct *tty;
100
101 cancel_work_sync(&speakup_sel_work.work);
102 /* setting to null so that if work fails to run and we cancel it,
103 * we can run it again without getting EBUSY forever from there on.
104 * we need to use xchg here to avoid race with speakup_set_selection()
105 */
106 tty = xchg(&speakup_sel_work.tty, NULL);
107 if (tty)
108 tty_kref_put(tty);
109 }
110
__speakup_paste_selection(struct work_struct * work)111 static void __speakup_paste_selection(struct work_struct *work)
112 {
113 struct speakup_selection_work *ssw =
114 container_of(work, struct speakup_selection_work, work);
115 struct tty_struct *tty = xchg(&ssw->tty, NULL);
116
117 paste_selection(tty);
118 tty_kref_put(tty);
119 }
120
121 static struct speakup_selection_work speakup_paste_work = {
122 .work = __WORK_INITIALIZER(speakup_paste_work.work,
123 __speakup_paste_selection)
124 };
125
speakup_paste_selection(struct tty_struct * tty)126 int speakup_paste_selection(struct tty_struct *tty)
127 {
128 tty_kref_get(tty);
129 if (cmpxchg(&speakup_paste_work.tty, NULL, tty)) {
130 tty_kref_put(tty);
131 return -EBUSY;
132 }
133
134 schedule_work_on(WORK_CPU_UNBOUND, &speakup_paste_work.work);
135 return 0;
136 }
137
speakup_cancel_paste(void)138 void speakup_cancel_paste(void)
139 {
140 struct tty_struct *tty;
141
142 cancel_work_sync(&speakup_paste_work.work);
143 tty = xchg(&speakup_paste_work.tty, NULL);
144 if (tty)
145 tty_kref_put(tty);
146 }
147
