Input: implement SysRq as a separate input handler

Instead of keeping SysRq support inside of legacy keyboard driver split
it out into a separate input handler (filter). This stops most SysRq input
events from leaking into evdev clients (some events, such as first SysRq
scancode - not keycode - event, are still leaked into both legacy keyboard
and evdev).

[martinez.javier@gmail.com: fix compile error when CONFIG_MAGIC_SYSRQ is
 not defined]
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

4 files changed, 246 insertions, 83 deletions

diff --git a/drivers/char/keyboard.c b/drivers/char/keyboard.c
index ada25bb8941e..50f6c01f44ec 100644
--- a/drivers/char/keyboard.c
+++ b/drivers/char/keyboard.c
@@ -38,7 +38,6 @@
 #include <linux/kbd_kern.h>
 #include <linux/kbd_diacr.h>
 #include <linux/vt_kern.h>
-#include <linux/sysrq.h>
 #include <linux/input.h>
 #include <linux/reboot.h>
 #include <linux/notifier.h>
@@ -82,8 +81,7 @@ void compute_shiftstate(void);
 typedef void (k_handler_fn)(struct vc_data *vc, unsigned char value,
                             char up_flag);
 static k_handler_fn K_HANDLERS;
-k_handler_fn *k_handler[16] = { K_HANDLERS };
-EXPORT_SYMBOL_GPL(k_handler);
+static k_handler_fn *k_handler[16] = { K_HANDLERS };
 
 #define FN_HANDLERS\
         fn_null,        fn_enter,       fn_show_ptregs, fn_show_mem,\
@@ -147,22 +145,6 @@ static struct ledptr {
         unsigned char valid:1;
 } ledptrs[3];
 
-/* Simple translation table for the SysRq keys */
-
-#ifdef CONFIG_MAGIC_SYSRQ
-unsigned char kbd_sysrq_xlate[KEY_MAX + 1] =
-        "\000\0331234567890-=\177\t"                    /* 0x00 - 0x0f */
-        "qwertyuiop[]\r\000as"                          /* 0x10 - 0x1f */
-        "dfghjkl;'`\000\\zxcv"                          /* 0x20 - 0x2f */
-        "bnm,./\000*\000 \000\201\202\203\204\205"      /* 0x30 - 0x3f */
-        "\206\207\210\211\212\000\000789-456+1"         /* 0x40 - 0x4f */
-        "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
-        "\r\000/";                                      /* 0x60 - 0x6f */
-static int sysrq_down;
-static int sysrq_alt_use;
-#endif
-static int sysrq_alt;
-
 /*
  * Notifier list for console keyboard events
  */
@@ -1108,7 +1090,8 @@ static int emulate_raw(struct vc_data *vc, unsigned int keycode,
                          * pressing PrtSc/SysRq alone, but simply 0x54
                          * when pressing Alt+PrtSc/SysRq.
                          */
-                        if (sysrq_alt) {
+                        if (test_bit(KEY_LEFTALT, key_down) ||
+                            test_bit(KEY_RIGHTALT, key_down)) {
                                 put_queue(vc, 0x54 | up_flag);
                         } else {
                                 put_queue(vc, 0xe0);
@@ -1176,8 +1159,6 @@ static void kbd_keycode(unsigned int keycode, int down, int hw_raw)
 
         kbd = kbd_table + vc->vc_num;
 
-        if (keycode == KEY_LEFTALT || keycode == KEY_RIGHTALT)
-                sysrq_alt = down ? keycode : 0;
 #ifdef CONFIG_SPARC
         if (keycode == KEY_STOP)
                 sparc_l1_a_state = down;
@@ -1190,21 +1171,6 @@ static void kbd_keycode(unsigned int keycode, int down, int hw_raw)
                         if (keycode < BTN_MISC && printk_ratelimit())
                                 printk(KERN_WARNING "keyboard.c: can't emulate rawmode for keycode %d\n", keycode);
 
-#ifdef CONFIG_MAGIC_SYSRQ              /* Handle the SysRq Hack */
-        if (keycode == KEY_SYSRQ && (sysrq_down || (down == 1 && sysrq_alt))) {
-                if (!sysrq_down) {
-                        sysrq_down = down;
-                        sysrq_alt_use = sysrq_alt;
-                }
-                return;
-        }
-        if (sysrq_down && !down && keycode == sysrq_alt_use)
-                sysrq_down = 0;
-        if (sysrq_down && down && !rep) {
-                handle_sysrq(kbd_sysrq_xlate[keycode], tty);
-                return;
-        }
-#endif
 #ifdef CONFIG_SPARC
         if (keycode == KEY_A && sparc_l1_a_state) {
                 sparc_l1_a_state = 0;
diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c
index 59de2525d303..193f9c214946 100644
--- a/drivers/char/sysrq.c
+++ b/drivers/char/sysrq.c
@@ -1,7 +1,4 @@
-/* -*- linux-c -*-
- *
- *      $Id: sysrq.c,v 1.15 1998/08/23 14:56:41 mj Exp $
- *
+/*
  *      Linux Magic System Request Key Hacks
  *
  *      (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
@@ -10,8 +7,13 @@
  *      (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
  *      overhauled to use key registration
  *      based upon discusions in irc://irc.openprojects.net/#kernelnewbies
+ *
+ *      Copyright (c) 2010 Dmitry Torokhov
+ *      Input handler conversion
  */
 
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
 #include <linux/sched.h>
 #include <linux/interrupt.h>
 #include <linux/mm.h>
@@ -39,33 +41,34 @@
 #include <linux/hrtimer.h>
 #include <linux/oom.h>
 #include <linux/slab.h>
+#include <linux/input.h>
 
 #include <asm/ptrace.h>
 #include <asm/irq_regs.h>
 
 /* Whether we react on sysrq keys or just ignore them */
-int __read_mostly __sysrq_enabled = 1;
-
-static int __read_mostly sysrq_always_enabled;
+static int __read_mostly sysrq_enabled = 1;
+static bool __read_mostly sysrq_always_enabled;
 
-int sysrq_on(void)
+static bool sysrq_on(void)
 {
-        return __sysrq_enabled || sysrq_always_enabled;
+        return sysrq_enabled || sysrq_always_enabled;
 }
 
 /*
  * A value of 1 means 'all', other nonzero values are an op mask:
  */
-static inline int sysrq_on_mask(int mask)
+static bool sysrq_on_mask(int mask)
 {
-        return sysrq_always_enabled || __sysrq_enabled == 1 ||
-                                                (__sysrq_enabled & mask);
+        return sysrq_always_enabled ||
+               sysrq_enabled == 1 ||
+               (sysrq_enabled & mask);
 }
 
 static int __init sysrq_always_enabled_setup(char *str)
 {
-        sysrq_always_enabled = 1;
-        printk(KERN_INFO "debug: sysrq always enabled.\n");
+        sysrq_always_enabled = true;
+        pr_info("sysrq always enabled.\n");
 
         return 1;
 }
@@ -76,6 +79,7 @@ __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
 static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
 {
         int i;
+
         i = key - '0';
         console_loglevel = 7;
         printk("Loglevel set to %d\n", i);
@@ -101,7 +105,7 @@ static struct sysrq_key_op sysrq_SAK_op = {
         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,