Each connected kbd_handle holds a keyboard config that contains the
keymap used to translate keycode into keysym. At init and until the
kbd_handle gets detached it uses the global keyboard config
(aka key_maps[]) array to translate keycode into keysym.

For now, it is not possible for the user to detach a kbd_handle from
global config. Some new ioctl will be introduced to do so.

Signed-off-by: Remi Pommarel <r...@triplefau.lt>
Tested-by: Elie Roudninski <xade...@gmail.com>
---
 drivers/tty/vt/keyboard.c | 198 ++++++++++++++++++++++++++++++++------
 1 file changed, 171 insertions(+), 27 deletions(-)

diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
index 89fabb8ae04e..4f09331ad5c3 100644
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -108,6 +108,23 @@ struct vt_spawn_console vt_spawn_con = {
  * Internal Data.
  */
 
+/* Input handle's specific key configuration */
+struct kbd_conf {
+       ushort **maps;
+       unsigned int keymap_count;
+};
+
+static struct kbd_conf _gkeyconf;
+#define KC_IS_GLOBAL(kc) ((kc) == &_gkeyconf)
+
+/* Input handle */
+struct kbd_handle {
+       struct kref ref;
+       struct kbd_conf *conf;
+       struct input_handle handle;
+};
+#define hdl_to_kbd_handle(h) (container_of(h, struct kbd_handle, handle))
+
 static struct kbd_struct kbd_table[MAX_NR_CONSOLES];
 static struct kbd_struct *kbd = kbd_table;
 
@@ -1343,9 +1360,11 @@ static void kbd_rawcode(unsigned char data)
                put_queue(vc, data);
 }
 
-static void kbd_keycode(unsigned int keycode, int down, int hw_raw)
+static void kbd_keycode(struct kbd_handle *kh, unsigned int keycode, int down,
+               int hw_raw)
 {
        struct vc_data *vc = vc_cons[fg_console].d;
+       struct kbd_conf *kconf = kh->conf;
        unsigned short keysym, *key_map;
        unsigned char type;
        bool raw_mode;
@@ -1422,7 +1441,7 @@ static void kbd_keycode(unsigned int keycode, int down, 
int hw_raw)
 
        param.shift = shift_final = (shift_state | kbd->slockstate) ^ 
kbd->lockstate;
        param.ledstate = kbd->ledflagstate;
-       key_map = key_maps[shift_final];
+       key_map = kconf->maps[shift_final];
 
        rc = atomic_notifier_call_chain(&keyboard_notifier_list,
                                        KBD_KEYCODE, &param);
@@ -1458,7 +1477,7 @@ static void kbd_keycode(unsigned int keycode, int down, 
int hw_raw)
        if (type == KT_LETTER) {
                type = KT_LATIN;
                if (vc_kbd_led(kbd, VC_CAPSLOCK)) {
-                       key_map = key_maps[shift_final ^ (1 << KG_SHIFT)];
+                       key_map = kconf->maps[shift_final ^ (1 << KG_SHIFT)];
                        if (key_map)
                                keysym = key_map[keycode];
                }
@@ -1485,13 +1504,15 @@ static void kbd_keycode(unsigned int keycode, int down, 
int hw_raw)
 static void kbd_event(struct input_handle *handle, unsigned int event_type,
                      unsigned int event_code, int value)
 {
+       struct kbd_handle *kh = hdl_to_kbd_handle(handle);
+
        /* We are called with interrupts disabled, just take the lock */
        spin_lock(&kbd_event_lock);
 
        if (event_type == EV_MSC && event_code == MSC_RAW && 
HW_RAW(handle->dev))
                kbd_rawcode(value);
        if (event_type == EV_KEY)
-               kbd_keycode(event_code, value, HW_RAW(handle->dev));
+               kbd_keycode(kh, event_code, value, HW_RAW(handle->dev));
 
        spin_unlock(&kbd_event_lock);
 
@@ -1519,6 +1540,114 @@ static bool kbd_match(struct input_handler *handler, 
struct input_dev *dev)
        return false;
 }
 
+/*
+ * Keyconf functions
+ */
+
+static void kbd_init_conf(struct kbd_handle *kh)
+{
+       kh->conf = &_gkeyconf;
+}
+
+/*
+ * Detach an input from global keyboard config. If keyboard config is already
+ * detached, nothing is modified.
+ */
+static int kbd_detach_conf(struct kbd_handle *kh)
+{
+       struct kbd_conf *kconf;
+       ushort **tmp, **maps = NULL;
+       size_t i, tmpcnt = 0;
+       unsigned long flags;
+       unsigned int count = 0;
+       int err = -ENOMEM;
+
+       kconf = kmalloc(sizeof(*kconf), GFP_KERNEL);
+       if (kconf == NULL)
+               goto reterr;
+
+       maps = kcalloc(MAX_NR_KEYMAPS, sizeof(*maps), GFP_KERNEL);
+       if (maps == NULL)
+               goto reterr;
+
+       tmp = kmalloc_array(MAX_NR_KEYMAPS, sizeof(*tmp), GFP_KERNEL);
+       if (tmp == NULL)
+               goto reterr;
+
+       spin_lock_irqsave(&kbd_event_lock, flags);
+
+       if (!KC_IS_GLOBAL(kh->conf))
+               goto out;  /* We have been raced at keymap creation */
+       count = kh->conf->keymap_count;
+
+       /* Pre-alloc enough tmp buffer to avoid allocating with lock held */
+       while (tmpcnt < count) {
+               spin_unlock_irqrestore(&kbd_event_lock, flags);
+               for (; tmpcnt < count; ++tmpcnt) {
+                       tmp[tmpcnt] = kmalloc(sizeof(plain_map), GFP_KERNEL);
+                       if (tmp[tmpcnt] == NULL)
+                               goto freetmp;
+               }
+               spin_lock_irqsave(&kbd_event_lock, flags);
+
+               if (!KC_IS_GLOBAL(kh->conf))
+                       goto out;  /* We have been raced at keymap creation */
+               count = kh->conf->keymap_count;
+       }
+
+       /*
+        * Here at least enough tmp pointers have been allocated and lock is
+        * held.
+        *
+        * If more than enough pointers have been allocated, the extra ones will
+        * be freed after (see freetmp).
+        */
+       if (count >= MAX_NR_OF_USER_KEYMAPS &&
+                       !capable(CAP_SYS_RESOURCE)) {
+               err = -EPERM;
+               goto unlock;
+       }
+       for (i = 0; i < MAX_NR_KEYMAPS; ++i) {
+               if (kh->conf->maps[i]) {
+                       --tmpcnt;
+                       memcpy(tmp[tmpcnt], kh->conf->maps[i],
+                                       sizeof(plain_map));
+                       tmp[tmpcnt][0] = U(K_ALLOCATED);
+                       maps[i] = tmp[tmpcnt];
+               }
+       }
+       kconf->maps = maps;
+       kconf->keymap_count = count;
+       kh->conf = kconf;
+       kconf = NULL;
+       maps = NULL;
+out:
+       err = 0;
+unlock:
+       spin_unlock_irqrestore(&kbd_event_lock, flags);
+freetmp:
+       for (; tmpcnt > 0; --tmpcnt) /* Free extra pointers */
+               kfree(tmp[tmpcnt - 1]);
+       kfree(tmp);
+reterr:
+       kfree(maps);
+       kfree(kconf);
+       return err;
+}
+
+static void kbd_destroy_conf(struct kbd_handle *kh)
+{
+       size_t i;
+
+       if (KC_IS_GLOBAL(kh->conf))
+               return;
+
+       for (i = 0; i < MAX_NR_KEYMAPS; ++i)
+               kfree(kh->conf->maps[i]);
+       kfree(kh->conf->maps);
+       kfree(kh->conf);
+}
+
 /*
  * When a keyboard (or other input device) is found, the kbd_connect
  * function is called. The function then looks at the device, and if it
@@ -1528,13 +1657,17 @@ static bool kbd_match(struct input_handler *handler, 
struct input_dev *dev)
 static int kbd_connect(struct input_handler *handler, struct input_dev *dev,
                        const struct input_device_id *id)
 {
+       struct kbd_handle *kh;
        struct input_handle *handle;
        int error;
 
-       handle = kzalloc(sizeof(struct input_handle), GFP_KERNEL);
-       if (!handle)
+       kh = kzalloc(sizeof(struct kbd_handle), GFP_KERNEL);
+       if (!kh)
                return -ENOMEM;
 
+       kref_init(&kh->ref);
+       kbd_init_conf(kh);
+       handle = &kh->handle;
        handle->dev = dev;
        handle->handler = handler;
        handle->name = "kbd";
@@ -1552,15 +1685,25 @@ static int kbd_connect(struct input_handler *handler, 
struct input_dev *dev,
  err_unregister_handle:
        input_unregister_handle(handle);
  err_free_handle:
-       kfree(handle);
+       kfree(kh);
        return error;
 }
 
+static void kbd_destroy(struct kref *ref)
+{
+       struct kbd_handle *kh = container_of(ref, struct kbd_handle, ref);
+
+       kbd_destroy_conf(kh);
+       kfree(kh);
+}
+
 static void kbd_disconnect(struct input_handle *handle)
 {
+       struct kbd_handle *kh = hdl_to_kbd_handle(handle);
+
        input_close_device(handle);
        input_unregister_handle(handle);
-       kfree(handle);
+       kref_put(&kh->ref, kbd_destroy);
 }
 
 /*
@@ -1619,6 +1762,8 @@ int __init kbd_init(void)
        }
 
        kbd_init_leds();
+       _gkeyconf.maps = key_maps;
+       _gkeyconf.keymap_count = keymap_count;
 
        error = input_register_handler(&kbd_handler);
        if (error)
@@ -1879,21 +2024,21 @@ int vt_do_kbkeycode_ioctl(int cmd, struct kbkeycode 
__user *user_kbkc,
 #define v (kbe->kb_value)
 
 /*
- * Get a keysym value from a key map
+ * Get a keysym value from a keyconf's keymap
  *
  * @kb: Virtual console structure
- * @kmaps: Key map array
+ * @kconf: Keyboard configuration
  * @kbe : Entry to find in key map
  */
-static ushort __kdsk_getent(struct kbd_struct const *kb, ushort **kmaps,
-               struct kbentry const *kbe)
+static ushort kc_getent(struct kbd_struct const *kb,
+               struct kbd_conf const *kconf, struct kbentry const *kbe)
 {
        ushort *key_map, val;
        unsigned long flags;
 
        /* Ensure another thread doesn't free it under us */
        spin_lock_irqsave(&kbd_event_lock, flags);
-       key_map = kmaps[s];
+       key_map = kconf->maps[s];
        if (key_map) {
                val = U(key_map[i]);
                if (kb->kbdmode != VC_UNICODE && KTYP(val) >= NR_TYPES)
@@ -1906,13 +2051,13 @@ static ushort __kdsk_getent(struct kbd_struct const 
*kb, ushort **kmaps,
 }
 
 /*
- * Set a keysym value in a key map
+ * Set a keysym value in a keyboard configuration's keymap
  *
  * @kb: Virtual console structure
- * @kmaps: Key map array
+ * @kconf: Keyboard configuration
  * @kbe : Entry to set in key map
  */
-static int __kdsk_setent(struct kbd_struct const *kb, ushort **kmaps,
+static int kc_setent(struct kbd_struct const *kb, struct kbd_conf *kconf,
                struct kbentry const *kbe)
 {
        ushort *key_map, *new_map, ov;
@@ -1921,13 +2066,12 @@ static int __kdsk_setent(struct kbd_struct const *kb, 
ushort **kmaps,
        if (!i && v == K_NOSUCHMAP) {
                spin_lock_irqsave(&kbd_event_lock, flags);
                /* deallocate map */
-               key_map = kmaps[s];
+               key_map = kconf->maps[s];
                if (s && key_map) {
-                       kmaps[s] = NULL;
-                       if (key_map[0] == U(K_ALLOCATED)) {
+                       kconf->maps[s] = NULL;
+                       if (key_map[0] == U(K_ALLOCATED))
                                kfree(key_map);
-                               keymap_count--;
-                       }
+                       kconf->keymap_count--;
                }
                spin_unlock_irqrestore(&kbd_event_lock, flags);
                return 0;
@@ -1950,22 +2094,22 @@ static int __kdsk_setent(struct kbd_struct const *kb, 
ushort **kmaps,
        if (!new_map)
                return -ENOMEM;
        spin_lock_irqsave(&kbd_event_lock, flags);
-       key_map = kmaps[s];
+       key_map = kconf->maps[s];
        if (key_map == NULL) {
                int j;
 
-               if (keymap_count >= MAX_NR_OF_USER_KEYMAPS &&
+               if (kconf->keymap_count >= MAX_NR_OF_USER_KEYMAPS &&
                                !capable(CAP_SYS_RESOURCE)) {
                        spin_unlock_irqrestore(&kbd_event_lock, flags);
                        kfree(new_map);
                        return -EPERM;
                }
-               kmaps[s] = new_map;
+               kconf->maps[s] = new_map;
                key_map = new_map;
                key_map[0] = U(K_ALLOCATED);
                for (j = 1; j < NR_KEYS; j++)
                        key_map[j] = U(K_HOLE);
-               keymap_count++;
+               kconf->keymap_count++;
        } else
                kfree(new_map);
 
@@ -2006,13 +2150,13 @@ int vt_do_kdsk_ioctl(int cmd, struct kbentry __user 
*user_kbe, int perm,
 
        switch (cmd) {
        case KDGKBENT:
-               val = __kdsk_getent(kb, key_maps, &tmp);
+               val = kc_getent(kb, &_gkeyconf, &tmp);
                ret = put_user(val, &user_kbe->kb_value);
                break;
        case KDSKBENT:
                if (!perm)
                        return -EPERM;
-               ret = __kdsk_setent(kb, key_maps, &tmp);
+               ret = kc_setent(kb, &_gkeyconf, &tmp);
                break;
        }
        return ret;
-- 
2.18.0

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