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_set_selection(struct work_struct * work)25 static 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
53 unref:
54 tty_kref_put(tty);
55 }
56
57 static struct speakup_selection_work speakup_sel_work = {
58 .work = __WORK_INITIALIZER(speakup_sel_work.work,
59 __speakup_set_selection)
60 };
61
speakup_set_selection(struct tty_struct * tty)62 int 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
speakup_cancel_selection(void)92 void 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
__speakup_paste_selection(struct work_struct * work)106 static 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
116 static struct speakup_selection_work speakup_paste_work = {
117 .work = __WORK_INITIALIZER(speakup_paste_work.work,
118 __speakup_paste_selection)
119 };
120
speakup_paste_selection(struct tty_struct * tty)121 int 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
speakup_cancel_paste(void)133 void 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