1 files changed, 265 insertions, 140 deletions

diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index 1f03078ec352..1f78b0db3b25 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -19,6 +19,7 @@
 #include <linux/sched/rt.h>
 #include <linux/sched/debug.h>
 #include <linux/sched/task.h>
+#include <linux/ctype.h>
 #include <linux/interrupt.h>
 #include <linux/mm.h>
 #include <linux/fs.h>
@@ -63,6 +64,19 @@ static bool sysrq_on(void)
 	return sysrq_enabled || sysrq_always_enabled;
 }
 
+/**
+ * sysrq_mask - Getter for sysrq_enabled mask.
+ *
+ * Return: 1 if sysrq is always enabled, enabled sysrq_key_op mask otherwise.
+ */
+int sysrq_mask(void)
+{
+	if (sysrq_always_enabled)
+		return 1;
+	return sysrq_enabled;
+}
+EXPORT_SYMBOL_GPL(sysrq_mask);
+
 /*
  * A value of 1 means 'all', other nonzero values are an op mask:
  */
@@ -84,16 +98,15 @@ static int __init sysrq_always_enabled_setup(char *str)
 __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
 
 
-static void sysrq_handle_loglevel(int key)
+static void sysrq_handle_loglevel(u8 key)
 {
-	int i;
+	u8 loglevel = key - '0';
 
-	i = key - '0';
 	console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
-	pr_info("Loglevel set to %d\n", i);
-	console_loglevel = i;
+	pr_info("Loglevel set to %u\n", loglevel);
+	console_loglevel = loglevel;
 }
-static struct sysrq_key_op sysrq_loglevel_op = {
+static const struct sysrq_key_op sysrq_loglevel_op = {
 	.handler	= sysrq_handle_loglevel,
 	.help_msg	= "loglevel(0-9)",
 	.action_msg	= "Changing Loglevel",
@@ -101,91 +114,94 @@ static struct sysrq_key_op sysrq_loglevel_op = {
 };
 
 #ifdef CONFIG_VT
-static void sysrq_handle_SAK(int key)
+static void sysrq_handle_SAK(u8 key)
 {
 	struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
+
 	schedule_work(SAK_work);
 }
-static struct sysrq_key_op sysrq_SAK_op = {
+static const struct sysrq_key_op sysrq_SAK_op = {
 	.handler	= sysrq_handle_SAK,
 	.help_msg	= "sak(k)",
 	.action_msg	= "SAK",
 	.enable_mask	= SYSRQ_ENABLE_KEYBOARD,
 };
 #else
-#define sysrq_SAK_op (*(struct sysrq_key_op *)NULL)
+#define sysrq_SAK_op (*(const struct sysrq_key_op *)NULL)
 #endif
 
 #ifdef CONFIG_VT
-static void sysrq_handle_unraw(int key)
+static void sysrq_handle_unraw(u8 key)
 {
 	vt_reset_unicode(fg_console);
 }
 
-static struct sysrq_key_op sysrq_unraw_op = {
+static const struct sysrq_key_op sysrq_unraw_op = {
 	.handler	= sysrq_handle_unraw,
 	.help_msg	= "unraw(r)",
 	.action_msg	= "Keyboard mode set to system default",
 	.enable_mask	= SYSRQ_ENABLE_KEYBOARD,
 };
 #else
-#define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
+#define sysrq_unraw_op (*(const struct sysrq_key_op *)NULL)
 #endif /* CONFIG_VT */
 
-static void sysrq_handle_crash(int key)
+static void sysrq_handle_crash(u8 key)
 {
 	/* release the RCU read lock before crashing */
 	rcu_read_unlock();
 
 	panic("sysrq triggered crash\n");
 }
-static struct sysrq_key_op sysrq_crash_op = {
+static const struct sysrq_key_op sysrq_crash_op = {
 	.handler	= sysrq_handle_crash,
 	.help_msg	= "crash(c)",
 	.action_msg	= "Trigger a crash",
 	.enable_mask	= SYSRQ_ENABLE_DUMP,
 };
 
-static void sysrq_handle_reboot(int key)
+static void sysrq_handle_reboot(u8 key)
 {
 	lockdep_off();
 	local_irq_enable();
 	emergency_restart();
 }
-static struct sysrq_key_op sysrq_reboot_op = {
+static const struct sysrq_key_op sysrq_reboot_op = {
 	.handler	= sysrq_handle_reboot,
 	.help_msg	= "reboot(b)",
 	.action_msg	= "Resetting",
 	.enable_mask	= SYSRQ_ENABLE_BOOT,
 };
 
-static void sysrq_handle_sync(int key)
+const struct sysrq_key_op *__sysrq_reboot_op = &sysrq_reboot_op;
+
+static void sysrq_handle_sync(u8 key)
 {
 	emergency_sync();
 }
-static struct sysrq_key_op sysrq_sync_op = {
+static const struct sysrq_key_op sysrq_sync_op = {
 	.handler	= sysrq_handle_sync,
 	.help_msg	= "sync(s)",
 	.action_msg	= "Emergency Sync",
 	.enable_mask	= SYSRQ_ENABLE_SYNC,
 };
 
-static void sysrq_handle_show_timers(int key)
+static void sysrq_handle_show_timers(u8 key)
 {
 	sysrq_timer_list_show();
 }
 
-static struct sysrq_key_op sysrq_show_timers_op = {
+static const struct sysrq_key_op sysrq_show_timers_op = {
 	.handler	= sysrq_handle_show_timers,
 	.help_msg	= "show-all-timers(q)",
 	.action_msg	= "Show clockevent devices & pending hrtimers (no others)",
 };
 
-static void sysrq_handle_mountro(int key)
+static void sysrq_handle_mountro(u8 key)
 {
 	emergency_remount();
 }
-static struct sysrq_key_op sysrq_mountro_op = {
+static const struct sysrq_key_op sysrq_mountro_op = {
 	.handler	= sysrq_handle_mountro,
 	.help_msg	= "unmount(u)",
 	.action_msg	= "Emergency Remount R/O",
@@ -193,35 +209,37 @@ static struct sysrq_key_op sysrq_mountro_op = {
 };
 
 #ifdef CONFIG_LOCKDEP
-static void sysrq_handle_showlocks(int key)
+static void sysrq_handle_showlocks(u8 key)
 {
 	debug_show_all_locks();
 }
 
-static struct sysrq_key_op sysrq_showlocks_op = {
+static const struct sysrq_key_op sysrq_showlocks_op = {
 	.handler	= sysrq_handle_showlocks,
 	.help_msg	= "show-all-locks(d)",
 	.action_msg	= "Show Locks Held",
 };
 #else
-#define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
+#define sysrq_showlocks_op (*(const struct sysrq_key_op *)NULL)
 #endif
 
 #ifdef CONFIG_SMP
-static DEFINE_SPINLOCK(show_lock);
+static DEFINE_RAW_SPINLOCK(show_lock);
 
 static void showacpu(void *dummy)
 {
 	unsigned long flags;
 
 	/* Idle CPUs have no interesting backtrace. */
-	if (idle_cpu(smp_processor_id()))
+	if (idle_cpu(smp_processor_id())) {
+		pr_info("CPU%d: backtrace skipped as idling\n", smp_processor_id());
 		return;
+	}
 
-	spin_lock_irqsave(&show_lock, flags);
+	raw_spin_lock_irqsave(&show_lock, flags);
 	pr_info("CPU%d:\n", smp_processor_id());
-	show_stack(NULL, NULL);
-	spin_unlock_irqrestore(&show_lock, flags);
+	show_stack(NULL, NULL, KERN_INFO);
+	raw_spin_unlock_irqrestore(&show_lock, flags);
 }
 
 static void sysrq_showregs_othercpus(struct work_struct *dummy)
@@ -231,7 +249,7 @@ static void sysrq_showregs_othercpus(struct work_struct *dummy)
 
 static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
 
-static void sysrq_handle_showallcpus(int key)
+static void sysrq_handle_showallcpus(u8 key)
 {
 	/*
 	 * Fall back to the workqueue based printing if the
@@ -241,58 +259,64 @@ static void sysrq_handle_showallcpus(int key)
 	if (!trigger_all_cpu_backtrace()) {
 		struct pt_regs *regs = NULL;
 
-		if (in_irq())
+		if (in_hardirq())
 			regs = get_irq_regs();
-		if (regs) {
-			pr_info("CPU%d:\n", smp_processor_id());
+
+		pr_info("CPU%d:\n", get_cpu());
+		if (regs)
 			show_regs(regs);
-		}
+		else
+			show_stack(NULL, NULL, KERN_INFO);
+
 		schedule_work(&sysrq_showallcpus);
+		put_cpu();
 	}
 }
 
-static struct sysrq_key_op sysrq_showallcpus_op = {
+static const struct sysrq_key_op sysrq_showallcpus_op = {
 	.handler	= sysrq_handle_showallcpus,
 	.help_msg	= "show-backtrace-all-active-cpus(l)",
 	.action_msg	= "Show backtrace of all active CPUs",
 	.enable_mask	= SYSRQ_ENABLE_DUMP,
 };
+#else
+#define sysrq_showallcpus_op (*(const struct sysrq_key_op *)NULL)
 #endif
 
-static void sysrq_handle_showregs(int key)
+static void sysrq_handle_showregs(u8 key)
 {
 	struct pt_regs *regs = NULL;
 
-	if (in_irq())
+	if (in_hardirq())
 		regs = get_irq_regs();
 	if (regs)
 		show_regs(regs);
 	perf_event_print_debug();
 }
-static struct sysrq_key_op sysrq_showregs_op = {
+static const struct sysrq_key_op sysrq_showregs_op = {
 	.handler	= sysrq_handle_showregs,
 	.help_msg	= "show-registers(p)",
 	.action_msg	= "Show Regs",
 	.enable_mask	= SYSRQ_ENABLE_DUMP,
 };
 
-static void sysrq_handle_showstate(int key)
+static void sysrq_handle_showstate(u8 key)
 {
 	show_state();
-	show_workqueue_state();
+	show_all_workqueues();
 }
-static struct sysrq_key_op sysrq_showstate_op = {
+static const struct sysrq_key_op sysrq_showstate_op = {
 	.handler	= sysrq_handle_showstate,
 	.help_msg	= "show-task-states(t)",
 	.action_msg	= "Show State",
 	.enable_mask	= SYSRQ_ENABLE_DUMP,
 };
 
-static void sysrq_handle_showstate_blocked(int key)
+static void sysrq_handle_showstate_blocked(u8 key)
 {
 	show_state_filter(TASK_UNINTERRUPTIBLE);
 }
-static struct sysrq_key_op sysrq_showstate_blocked_op = {
+static const struct sysrq_key_op sysrq_showstate_blocked_op = {
 	.handler	= sysrq_handle_showstate_blocked,
 	.help_msg	= "show-blocked-tasks(w)",
 	.action_msg	= "Show Blocked State",
@@ -302,25 +326,25 @@ static struct sysrq_key_op sysrq_showstate_blocked_op = {
 #ifdef CONFIG_TRACING
 #include <linux/ftrace.h>
 
-static void sysrq_ftrace_dump(int key)
+static void sysrq_ftrace_dump(u8 key)
 {
 	ftrace_dump(DUMP_ALL);
 }
-static struct sysrq_key_op sysrq_ftrace_dump_op = {
+static const struct sysrq_key_op sysrq_ftrace_dump_op = {
 	.handler	= sysrq_ftrace_dump,
 	.help_msg	= "dump-ftrace-buffer(z)",
 	.action_msg	= "Dump ftrace buffer",
 	.enable_mask	= SYSRQ_ENABLE_DUMP,
 };
 #else
-#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
+#define sysrq_ftrace_dump_op (*(const struct sysrq_key_op *)NULL)
 #endif
 
-static void sysrq_handle_showmem(int key)
+static void sysrq_handle_showmem(u8 key)
 {
-	show_mem(0, NULL);
+	show_mem();
 }
-static struct sysrq_key_op sysrq_showmem_op = {
+static const struct sysrq_key_op sysrq_showmem_op = {
 	.handler	= sysrq_handle_showmem,
 	.help_msg	= "show-memory-usage(m)",
 	.action_msg	= "Show Memory",
@@ -346,12 +370,12 @@ static void send_sig_all(int sig)
 	read_unlock(&tasklist_lock);
 }
 
-static void sysrq_handle_term(int key)
+static void sysrq_handle_term(u8 key)
 {
 	send_sig_all(SIGTERM);
 	console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
 }
-static struct sysrq_key_op sysrq_term_op = {
+static const struct sysrq_key_op sysrq_term_op = {
 	.handler	= sysrq_handle_term,
 	.help_msg	= "terminate-all-tasks(e)",
 	.action_msg	= "Terminate All Tasks",
@@ -377,11 +401,11 @@ static void moom_callback(struct work_struct *ignored)
 
 static DECLARE_WORK(moom_work, moom_callback);
 
-static void sysrq_handle_moom(int key)
+static void sysrq_handle_moom(u8 key)
 {
 	schedule_work(&moom_work);
 }
-static struct sysrq_key_op sysrq_moom_op = {
+static const struct sysrq_key_op sysrq_moom_op = {
 	.handler	= sysrq_handle_moom,
 	.help_msg	= "memory-full-oom-kill(f)",
 	.action_msg	= "Manual OOM execution",
@@ -389,45 +413,58 @@ static struct sysrq_key_op sysrq_moom_op = {
 };
 
 #ifdef CONFIG_BLOCK
-static void sysrq_handle_thaw(int key)
+static void sysrq_handle_thaw(u8 key)
 {
 	emergency_thaw_all();
 }
-static struct sysrq_key_op sysrq_thaw_op = {
+static const struct sysrq_key_op sysrq_thaw_op = {
 	.handler	= sysrq_handle_thaw,
 	.help_msg	= "thaw-filesystems(j)",
 	.action_msg	= "Emergency Thaw of all frozen filesystems",
 	.enable_mask	= SYSRQ_ENABLE_SIGNAL,
 };
+#else
+#define sysrq_thaw_op (*(const struct sysrq_key_op *)NULL)
 #endif
 
-static void sysrq_handle_kill(int key)
+static void sysrq_handle_kill(u8 key)
 {
 	send_sig_all(SIGKILL);
 	console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
 }
-static struct sysrq_key_op sysrq_kill_op = {
+static const struct sysrq_key_op sysrq_kill_op = {
 	.handler	= sysrq_handle_kill,
 	.help_msg	= "kill-all-tasks(i)",
 	.action_msg	= "Kill All Tasks",
 	.enable_mask	= SYSRQ_ENABLE_SIGNAL,
 };
 
-static void sysrq_handle_unrt(int key)
+static void sysrq_handle_unrt(u8 key)
 {
 	normalize_rt_tasks();
 }
-static struct sysrq_key_op sysrq_unrt_op = {
+static const struct sysrq_key_op sysrq_unrt_op = {
 	.handler	= sysrq_handle_unrt,
 	.help_msg	= "nice-all-RT-tasks(n)",
 	.action_msg	= "Nice All RT Tasks",
 	.enable_mask	= SYSRQ_ENABLE_RTNICE,
 };
 
+static void sysrq_handle_replay_logs(u8 key)
+{
+	console_try_replay_all();
+}
+static struct sysrq_key_op sysrq_replay_logs_op = {
+	.handler        = sysrq_handle_replay_logs,
+	.help_msg       = "replay-kernel-logs(R)",
+	.action_msg     = "Replay kernel logs on consoles",
+	.enable_mask    = SYSRQ_ENABLE_DUMP,
+};
+
 /* Key Operations table and lock */
 static DEFINE_SPINLOCK(sysrq_key_table_lock);
 
-static struct sysrq_key_op *sysrq_key_table[36] = {
+static const struct sysrq_key_op *sysrq_key_table[62] = {
 	&sysrq_loglevel_op,		/* 0 */
 	&sysrq_loglevel_op,		/* 1 */
 	&sysrq_loglevel_op,		/* 2 */
@@ -453,17 +490,9 @@ static struct sysrq_key_op *sysrq_key_table[36] = {
 	NULL,				/* g */
 	NULL,				/* h - reserved for help */
 	&sysrq_kill_op,			/* i */
-#ifdef CONFIG_BLOCK
 	&sysrq_thaw_op,			/* j */
-#else
-	NULL,				/* j */
-#endif
 	&sysrq_SAK_op,			/* k */
-#ifdef CONFIG_SMP
 	&sysrq_showallcpus_op,		/* l */
-#else
-	NULL,				/* l */
-#endif
 	&sysrq_showmem_op,		/* m */
 	&sysrq_unrt_op,			/* n */
 	/* o: This will often be registered as 'Off' at init time */
@@ -484,78 +513,108 @@ static struct sysrq_key_op *sysrq_key_table[36] = {
 	/* y: May be registered on sparc64 for global register dump */
 	NULL,				/* y */
 	&sysrq_ftrace_dump_op,		/* z */
+	NULL,				/* A */
+	NULL,				/* B */
+	NULL,				/* C */
+	NULL,				/* D */
+	NULL,				/* E */
+	NULL,				/* F */
+	NULL,				/* G */
+	NULL,				/* H */
+	NULL,				/* I */
+	NULL,				/* J */
+	NULL,				/* K */
+	NULL,				/* L */
+	NULL,				/* M */
+	NULL,				/* N */
+	NULL,				/* O */
+	NULL,				/* P */
+	NULL,				/* Q */
+	&sysrq_replay_logs_op,		/* R */
+	/* S: May be registered by sched_ext for resetting */
+	NULL,				/* S */
+	NULL,				/* T */
+	NULL,				/* U */
+	NULL,				/* V */
+	NULL,				/* W */
+	NULL,				/* X */
+	NULL,				/* Y */
+	NULL,				/* Z */
 };
 
 /* key2index calculation, -1 on invalid index */
-static int sysrq_key_table_key2index(int key)
+static int sysrq_key_table_key2index(u8 key)
 {
-	int retval;
-
-	if ((key >= '0') && (key <= '9'))
-		retval = key - '0';
-	else if ((key >= 'a') && (key <= 'z'))
-		retval = key + 10 - 'a';
-	else
-		retval = -1;
-	return retval;
+	switch (key) {
+	case '0' ... '9':
+		return key - '0';
+	case 'a' ... 'z':
+		return key - 'a' + 10;
+	case 'A' ... 'Z':
+		return key - 'A' + 10 + 26;
+	default:
+		return -1;
+	}
 }
 
 /*
  * get and put functions for the table, exposed to modules.
  */
-struct sysrq_key_op *__sysrq_get_key_op(int key)
+static const struct sysrq_key_op *__sysrq_get_key_op(u8 key)
 {
-        struct sysrq_key_op *op_p = NULL;
-        int i;
+	const struct sysrq_key_op *op_p = NULL;
+	int i;
 
 	i = sysrq_key_table_key2index(key);
 	if (i != -1)
-	        op_p = sysrq_key_table[i];
+		op_p = sysrq_key_table[i];
 
-        return op_p;
+	return op_p;
 }
 
-static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
+static void __sysrq_put_key_op(u8 key, const struct sysrq_key_op *op_p)
 {
-        int i = sysrq_key_table_key2index(key);
+	int i = sysrq_key_table_key2index(key);
 
-        if (i != -1)
-                sysrq_key_table[i] = op_p;
+	if (i != -1)
+		sysrq_key_table[i] = op_p;
 }
 
-void __handle_sysrq(int key, bool check_mask)
+void __handle_sysrq(u8 key, bool check_mask)
 {
-	struct sysrq_key_op *op_p;
-	int orig_log_level;
+	const struct sysrq_key_op *op_p;
+	int orig_suppress_printk;
 	int i;
 
+	orig_suppress_printk = suppress_printk;
+	suppress_printk = 0;
+
 	rcu_sysrq_start();
 	rcu_read_lock();
 	/*
-	 * Raise the apparent loglevel to maximum so that the sysrq header
-	 * is shown to provide the user with positive feedback.  We do not
-	 * simply emit this at KERN_EMERG as that would change message
-	 * routing in the consumers of /proc/kmsg.
+	 * Enter in the force_console context so that sysrq header is shown to
+	 * provide the user with positive feedback.  We do not simply emit this
+	 * at KERN_EMERG as that would change message routing in the consumers
+	 * of /proc/kmsg.
 	 */
-	orig_log_level = console_loglevel;
-	console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
-	pr_info("SysRq : ");
+	printk_force_console_enter();
 
-        op_p = __sysrq_get_key_op(key);
-        if (op_p) {
+	op_p = __sysrq_get_key_op(key);
+	if (op_p) {
 		/*
 		 * Should we check for enabled operations (/proc/sysrq-trigger
 		 * should not) and is the invoked operation enabled?
 		 */
 		if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
-			pr_cont("%s\n", op_p->action_msg);
-			console_loglevel = orig_log_level;
+			pr_info("%s\n", op_p->action_msg);
+			printk_force_console_exit();
 			op_p->handler(key);
 		} else {
-			pr_cont("This sysrq operation is disabled.\n");
+			pr_info("This sysrq operation is disabled.\n");
+			printk_force_console_exit();
 		}
 	} else {
-		pr_cont("HELP : ");
+		pr_info("HELP : ");
 		/* Only print the help msg once per handler */
 		for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
 			if (sysrq_key_table[i]) {
@@ -570,13 +629,15 @@ void __handle_sysrq(int key, bool check_mask)
 			}
 		}
 		pr_cont("\n");
-		console_loglevel = orig_log_level;
+		printk_force_console_exit();
 	}
 	rcu_read_unlock();
 	rcu_sysrq_end();
+
+	suppress_printk = orig_suppress_printk;
 }
 
-void handle_sysrq(int key)
+void handle_sysrq(u8 key)
 {
 	if (sysrq_on())
 		__handle_sysrq(key, true);
@@ -588,13 +649,13 @@ static int sysrq_reset_downtime_ms;
 
 /* Simple translation table for the SysRq keys */
 static const unsigned char sysrq_xlate[KEY_CNT] =
-        "\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 */
+	"\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 */
 
 struct sysrq_state {
 	struct input_handle handle;
@@ -602,6 +663,8 @@ struct sysrq_state {
 	unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
 	unsigned int alt;
 	unsigned int alt_use;
+	unsigned int shift;
+	unsigned int shift_use;
 	bool active;
 	bool need_reinject;
 	bool reinjecting;
@@ -649,7 +712,8 @@ static void sysrq_parse_reset_sequence(struct sysrq_state *state)
 
 static void sysrq_do_reset(struct timer_list *t)
 {
-	struct sysrq_state *state = from_timer(state, t, keyreset_timer);
+	struct sysrq_state *state = timer_container_of(state, t,
+						       keyreset_timer);
 
 	state->reset_requested = true;
 
@@ -680,7 +744,7 @@ static void sysrq_detect_reset_sequence(struct sysrq_state *state,
 		 */
 		if (value && state->reset_seq_cnt) {
 			state->reset_canceled = true;
-			del_timer(&state->keyreset_timer);
+			timer_delete(&state->keyreset_timer);
 		}
 	} else if (value == 0) {
 		/*
@@ -688,7 +752,7 @@ static void sysrq_detect_reset_sequence(struct sysrq_state *state,
 		 * to be pressed and held for the reset timeout
 		 * to hold.
 		 */
-		del_timer(&state->keyreset_timer);
+		timer_delete(&state->keyreset_timer);
 
 		if (--state->reset_seq_cnt == 0)
 			state->reset_canceled = false;
@@ -706,8 +770,6 @@ static void sysrq_of_get_keyreset_config(void)
 {
 	u32 key;
 	struct device_node *np;
-	struct property *prop;
-	const __be32 *p;
 
 	np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
 	if (!np) {
@@ -718,7 +780,7 @@ static void sysrq_of_get_keyreset_config(void)
 	/* Reset in case a __weak definition was present */
 	sysrq_reset_seq_len = 0;
 
-	of_property_for_each_u32(np, "keyset", prop, p, key) {
+	of_property_for_each_u32(np, "keyset", key) {
 		if (key == KEY_RESERVED || key > KEY_MAX ||
 		    sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX)
 			break;
@@ -786,10 +848,22 @@ static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
 		}
 		break;
 
+	case KEY_LEFTSHIFT:
+	case KEY_RIGHTSHIFT:
+		if (!value)
+			sysrq->shift = KEY_RESERVED;
+		else if (value != 2)
+			sysrq->shift = code;
+		if (sysrq->active)
+			sysrq->shift_use = sysrq->shift;
+		break;
+
 	case KEY_SYSRQ:
 		if (value == 1 && sysrq->alt != KEY_RESERVED) {
 			sysrq->active = true;
 			sysrq->alt_use = sysrq->alt;
+			/* either RESERVED (for released) or actual code */
+			sysrq->shift_use = sysrq->shift;
 			/*
 			 * If nothing else will be pressed we'll need
 			 * to re-inject Alt-SysRq keysroke.
@@ -812,8 +886,12 @@ static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
 
 	default:
 		if (sysrq->active && value && value != 2) {
+			unsigned char c = sysrq_xlate[code];
+
 			sysrq->need_reinject = false;
-			__handle_sysrq(sysrq_xlate[code], true);
+			if (sysrq->shift_use != KEY_RESERVED)
+				c = toupper(c);
+			__handle_sysrq(c, true);
 		}
 		break;
 	}
@@ -933,7 +1011,7 @@ static void sysrq_disconnect(struct input_handle *handle)
 
 	input_close_device(handle);
 	cancel_work_sync(&sysrq->reinject_work);
-	del_timer_sync(&sysrq->keyreset_timer);
+	timer_shutdown_sync(&sysrq->keyreset_timer);
 	input_unregister_handle(handle);
 	kfree(sysrq);
 }
@@ -961,8 +1039,6 @@ static struct input_handler sysrq_handler = {
 	.id_table	= sysrq_ids,
 };
 
-static bool sysrq_handler_registered;
-
 static inline void sysrq_register_handler(void)
 {
 	int error;
@@ -972,16 +1048,11 @@ static inline void sysrq_register_handler(void)
 	error = input_register_handler(&sysrq_handler);
 	if (error)
 		pr_err("Failed to register input handler, error %d", error);
-	else
-		sysrq_handler_registered = true;
 }
 
 static inline void sysrq_unregister_handler(void)
 {
-	if (sysrq_handler_registered) {
-		input_unregister_handler(&sysrq_handler);
-		sysrq_handler_registered = false;
-	}
+	input_unregister_handler(&sysrq_handler);
 }
 
 static int sysrq_reset_seq_param_set(const char *buffer,
@@ -1047,9 +1118,50 @@ int sysrq_toggle_support(int enable_mask)
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(sysrq_toggle_support);
+
+static int sysrq_sysctl_handler(const struct ctl_table *table, int write,
+				void *buffer, size_t *lenp, loff_t *ppos)
+{
+	int tmp, ret;
+	struct ctl_table t = *table;
+
+	tmp = sysrq_mask();
+	t.data = &tmp;
+
+	/*
+	 * Behaves like do_proc_dointvec as t does not have min nor max.
+	 */
+	ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
+	if (ret)
+		return ret;
+
+	if (write)
+		sysrq_toggle_support(tmp);
+
+	return 0;
+}
 
-static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
-                                struct sysrq_key_op *remove_op_p)
+static const struct ctl_table sysrq_sysctl_table[] = {
+	{
+		.procname	= "sysrq",
+		.data		= NULL,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= sysrq_sysctl_handler,
+	},
+};
+
+static int __init init_sysrq_sysctl(void)
+{
+	register_sysctl_init("kernel", sysrq_sysctl_table);
+	return 0;
+}
+
+subsys_initcall(init_sysrq_sysctl);
+
+static int __sysrq_swap_key_ops(u8 key, const struct sysrq_key_op *insert_op_p,
+				const struct sysrq_key_op *remove_op_p)
 {
 	int retval;
 
@@ -1072,13 +1184,13 @@ static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
 	return retval;
 }
 
-int register_sysrq_key(int key, struct sysrq_key_op *op_p)
+int register_sysrq_key(u8 key, const struct sysrq_key_op *op_p)
 {
 	return __sysrq_swap_key_ops(key, op_p, NULL);
 }
 EXPORT_SYMBOL(register_sysrq_key);
 
-int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
+int unregister_sysrq_key(u8 key, const struct sysrq_key_op *op_p)
 {
 	return __sysrq_swap_key_ops(key, NULL, op_p);
 }
@@ -1087,30 +1199,43 @@ EXPORT_SYMBOL(unregister_sysrq_key);
 #ifdef CONFIG_PROC_FS
 /*
  * writing 'C' to /proc/sysrq-trigger is like sysrq-C
+ * Normally, only the first character written is processed.
+ * However, if the first character is an underscore,
+ * all characters are processed.
  */
 static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
 				   size_t count, loff_t *ppos)
 {
-	if (count) {
+	bool bulk = false;
+	size_t i;
+
+	for (i = 0; i < count; i++) {
 		char c;
 
-		if (get_user(c, buf))
+		if (get_user(c, buf + i))
 			return -EFAULT;
-		__handle_sysrq(c, false);
+
+		if (c == '_')
+			bulk = true;
+		else
+			__handle_sysrq(c, false);
+
+		if (!bulk)
+			break;
 	}
 
 	return count;
 }
 
-static const struct file_operations proc_sysrq_trigger_operations = {
-	.write		= write_sysrq_trigger,
-	.llseek		= noop_llseek,
+static const struct proc_ops sysrq_trigger_proc_ops = {
+	.proc_write	= write_sysrq_trigger,
+	.proc_lseek	= noop_llseek,
 };
 
 static void sysrq_init_procfs(void)
 {
 	if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
-			 &proc_sysrq_trigger_operations))
+			 &sysrq_trigger_proc_ops))
 		pr_err("Failed to register proc interface\n");
 }