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Once kthread printing is available, console printing will no longer occur in the context of the printk caller. However, there are some special contexts where it is desirable for the printk caller to directly print out kernel messages. Using pr_flush() to wait for threaded printers is only possible if the caller is in a sleepable context and the kthreads are active. That is not always the case. Introduce printk_prefer_direct_enter() and printk_prefer_direct_exit() functions to explicitly (and globally) activate/deactivate preferred direct console printing. The term "direct console printing" refers to printing to all enabled consoles from the context of the printk caller. The term "prefer" is used because this type of printing is only best effort. If the console is currently locked or other printers are already actively printing, the printk caller will need to rely on the other contexts to handle the printing. This preferred direct printing is how all printing has been handled until now (unless it was explicitly deferred). When kthread printing is introduced, there may be some unanticipated problems due to kthreads being unable to flush important messages. In order to minimize such risks, preferred direct printing is activated for the primary important messages when the system experiences general types of major errors. These are: - emergency reboot/shutdown - cpu and rcu stalls - hard and soft lockups - hung tasks - warn - sysrq Note that since kthread printing does not yet exist, no behavior changes result from this commit. This is only implementing the counter and marking the various places where preferred direct printing is active. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Paul E. McKenney <paulmck@kernel.org> # for RCU Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20220421212250.565456-13-john.ogness@linutronix.de
1198 lines
28 KiB
C
1198 lines
28 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Linux Magic System Request Key Hacks
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*
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* (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
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* based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
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*
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* (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
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* overhauled to use key registration
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* based upon discusions in irc://irc.openprojects.net/#kernelnewbies
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*
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* Copyright (c) 2010 Dmitry Torokhov
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* Input handler conversion
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/sched/signal.h>
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#include <linux/sched/rt.h>
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#include <linux/sched/debug.h>
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#include <linux/sched/task.h>
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#include <linux/ctype.h>
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#include <linux/interrupt.h>
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include <linux/mount.h>
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#include <linux/kdev_t.h>
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#include <linux/major.h>
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#include <linux/reboot.h>
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#include <linux/sysrq.h>
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#include <linux/kbd_kern.h>
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#include <linux/proc_fs.h>
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#include <linux/nmi.h>
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#include <linux/quotaops.h>
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#include <linux/perf_event.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/suspend.h>
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#include <linux/writeback.h>
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#include <linux/swap.h>
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#include <linux/spinlock.h>
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#include <linux/vt_kern.h>
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#include <linux/workqueue.h>
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#include <linux/hrtimer.h>
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#include <linux/oom.h>
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#include <linux/slab.h>
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#include <linux/input.h>
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#include <linux/uaccess.h>
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#include <linux/moduleparam.h>
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#include <linux/jiffies.h>
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#include <linux/syscalls.h>
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#include <linux/of.h>
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#include <linux/rcupdate.h>
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#include <asm/ptrace.h>
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#include <asm/irq_regs.h>
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/* Whether we react on sysrq keys or just ignore them */
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static int __read_mostly sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE;
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static bool __read_mostly sysrq_always_enabled;
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static bool sysrq_on(void)
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{
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return sysrq_enabled || sysrq_always_enabled;
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}
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/**
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* sysrq_mask - Getter for sysrq_enabled mask.
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*
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* Return: 1 if sysrq is always enabled, enabled sysrq_key_op mask otherwise.
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*/
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int sysrq_mask(void)
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{
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if (sysrq_always_enabled)
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return 1;
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return sysrq_enabled;
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}
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EXPORT_SYMBOL_GPL(sysrq_mask);
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/*
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* A value of 1 means 'all', other nonzero values are an op mask:
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*/
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static bool sysrq_on_mask(int mask)
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{
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return sysrq_always_enabled ||
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sysrq_enabled == 1 ||
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(sysrq_enabled & mask);
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}
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static int __init sysrq_always_enabled_setup(char *str)
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{
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sysrq_always_enabled = true;
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pr_info("sysrq always enabled.\n");
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return 1;
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}
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__setup("sysrq_always_enabled", sysrq_always_enabled_setup);
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static void sysrq_handle_loglevel(int key)
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{
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int i;
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i = key - '0';
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console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
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pr_info("Loglevel set to %d\n", i);
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console_loglevel = i;
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}
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static const struct sysrq_key_op sysrq_loglevel_op = {
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.handler = sysrq_handle_loglevel,
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.help_msg = "loglevel(0-9)",
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.action_msg = "Changing Loglevel",
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.enable_mask = SYSRQ_ENABLE_LOG,
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};
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#ifdef CONFIG_VT
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static void sysrq_handle_SAK(int key)
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{
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struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
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schedule_work(SAK_work);
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}
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static const struct sysrq_key_op sysrq_SAK_op = {
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.handler = sysrq_handle_SAK,
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.help_msg = "sak(k)",
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.action_msg = "SAK",
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.enable_mask = SYSRQ_ENABLE_KEYBOARD,
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};
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#else
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#define sysrq_SAK_op (*(const struct sysrq_key_op *)NULL)
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#endif
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#ifdef CONFIG_VT
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static void sysrq_handle_unraw(int key)
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{
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vt_reset_unicode(fg_console);
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}
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static const struct sysrq_key_op sysrq_unraw_op = {
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.handler = sysrq_handle_unraw,
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.help_msg = "unraw(r)",
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.action_msg = "Keyboard mode set to system default",
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.enable_mask = SYSRQ_ENABLE_KEYBOARD,
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};
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#else
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#define sysrq_unraw_op (*(const struct sysrq_key_op *)NULL)
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#endif /* CONFIG_VT */
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static void sysrq_handle_crash(int key)
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{
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/* release the RCU read lock before crashing */
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rcu_read_unlock();
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panic("sysrq triggered crash\n");
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}
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static const struct sysrq_key_op sysrq_crash_op = {
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.handler = sysrq_handle_crash,
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.help_msg = "crash(c)",
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.action_msg = "Trigger a crash",
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.enable_mask = SYSRQ_ENABLE_DUMP,
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};
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static void sysrq_handle_reboot(int key)
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{
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lockdep_off();
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local_irq_enable();
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emergency_restart();
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}
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static const struct sysrq_key_op sysrq_reboot_op = {
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.handler = sysrq_handle_reboot,
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.help_msg = "reboot(b)",
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.action_msg = "Resetting",
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.enable_mask = SYSRQ_ENABLE_BOOT,
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};
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const struct sysrq_key_op *__sysrq_reboot_op = &sysrq_reboot_op;
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static void sysrq_handle_sync(int key)
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{
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emergency_sync();
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}
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static const struct sysrq_key_op sysrq_sync_op = {
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.handler = sysrq_handle_sync,
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.help_msg = "sync(s)",
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.action_msg = "Emergency Sync",
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.enable_mask = SYSRQ_ENABLE_SYNC,
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};
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static void sysrq_handle_show_timers(int key)
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{
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sysrq_timer_list_show();
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}
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static const struct sysrq_key_op sysrq_show_timers_op = {
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.handler = sysrq_handle_show_timers,
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.help_msg = "show-all-timers(q)",
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.action_msg = "Show clockevent devices & pending hrtimers (no others)",
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};
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static void sysrq_handle_mountro(int key)
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{
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emergency_remount();
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}
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static const struct sysrq_key_op sysrq_mountro_op = {
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.handler = sysrq_handle_mountro,
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.help_msg = "unmount(u)",
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.action_msg = "Emergency Remount R/O",
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.enable_mask = SYSRQ_ENABLE_REMOUNT,
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};
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#ifdef CONFIG_LOCKDEP
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static void sysrq_handle_showlocks(int key)
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{
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debug_show_all_locks();
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}
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static const struct sysrq_key_op sysrq_showlocks_op = {
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.handler = sysrq_handle_showlocks,
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.help_msg = "show-all-locks(d)",
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.action_msg = "Show Locks Held",
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};
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#else
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#define sysrq_showlocks_op (*(const struct sysrq_key_op *)NULL)
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#endif
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#ifdef CONFIG_SMP
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static DEFINE_RAW_SPINLOCK(show_lock);
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static void showacpu(void *dummy)
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{
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unsigned long flags;
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/* Idle CPUs have no interesting backtrace. */
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if (idle_cpu(smp_processor_id()))
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return;
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raw_spin_lock_irqsave(&show_lock, flags);
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pr_info("CPU%d:\n", smp_processor_id());
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show_stack(NULL, NULL, KERN_INFO);
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raw_spin_unlock_irqrestore(&show_lock, flags);
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}
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static void sysrq_showregs_othercpus(struct work_struct *dummy)
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{
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smp_call_function(showacpu, NULL, 0);
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}
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static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
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static void sysrq_handle_showallcpus(int key)
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{
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/*
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* Fall back to the workqueue based printing if the
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* backtrace printing did not succeed or the
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* architecture has no support for it:
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*/
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if (!trigger_all_cpu_backtrace()) {
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struct pt_regs *regs = NULL;
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if (in_hardirq())
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regs = get_irq_regs();
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if (regs) {
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pr_info("CPU%d:\n", smp_processor_id());
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show_regs(regs);
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}
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schedule_work(&sysrq_showallcpus);
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}
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}
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static const struct sysrq_key_op sysrq_showallcpus_op = {
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.handler = sysrq_handle_showallcpus,
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.help_msg = "show-backtrace-all-active-cpus(l)",
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.action_msg = "Show backtrace of all active CPUs",
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.enable_mask = SYSRQ_ENABLE_DUMP,
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};
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#endif
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static void sysrq_handle_showregs(int key)
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{
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struct pt_regs *regs = NULL;
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if (in_hardirq())
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regs = get_irq_regs();
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if (regs)
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show_regs(regs);
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perf_event_print_debug();
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}
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static const struct sysrq_key_op sysrq_showregs_op = {
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.handler = sysrq_handle_showregs,
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.help_msg = "show-registers(p)",
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.action_msg = "Show Regs",
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.enable_mask = SYSRQ_ENABLE_DUMP,
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};
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static void sysrq_handle_showstate(int key)
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{
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show_state();
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show_all_workqueues();
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}
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static const struct sysrq_key_op sysrq_showstate_op = {
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.handler = sysrq_handle_showstate,
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.help_msg = "show-task-states(t)",
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.action_msg = "Show State",
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.enable_mask = SYSRQ_ENABLE_DUMP,
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};
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static void sysrq_handle_showstate_blocked(int key)
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{
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show_state_filter(TASK_UNINTERRUPTIBLE);
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}
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static const struct sysrq_key_op sysrq_showstate_blocked_op = {
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.handler = sysrq_handle_showstate_blocked,
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.help_msg = "show-blocked-tasks(w)",
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.action_msg = "Show Blocked State",
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.enable_mask = SYSRQ_ENABLE_DUMP,
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};
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#ifdef CONFIG_TRACING
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#include <linux/ftrace.h>
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static void sysrq_ftrace_dump(int key)
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{
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ftrace_dump(DUMP_ALL);
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}
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static const struct sysrq_key_op sysrq_ftrace_dump_op = {
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.handler = sysrq_ftrace_dump,
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.help_msg = "dump-ftrace-buffer(z)",
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.action_msg = "Dump ftrace buffer",
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.enable_mask = SYSRQ_ENABLE_DUMP,
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};
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#else
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#define sysrq_ftrace_dump_op (*(const struct sysrq_key_op *)NULL)
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#endif
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static void sysrq_handle_showmem(int key)
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{
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show_mem(0, NULL);
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}
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static const struct sysrq_key_op sysrq_showmem_op = {
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.handler = sysrq_handle_showmem,
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.help_msg = "show-memory-usage(m)",
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.action_msg = "Show Memory",
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.enable_mask = SYSRQ_ENABLE_DUMP,
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};
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/*
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* Signal sysrq helper function. Sends a signal to all user processes.
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*/
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static void send_sig_all(int sig)
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{
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struct task_struct *p;
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read_lock(&tasklist_lock);
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for_each_process(p) {
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if (p->flags & PF_KTHREAD)
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continue;
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if (is_global_init(p))
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continue;
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do_send_sig_info(sig, SEND_SIG_PRIV, p, PIDTYPE_MAX);
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}
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read_unlock(&tasklist_lock);
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}
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static void sysrq_handle_term(int key)
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{
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send_sig_all(SIGTERM);
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console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
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}
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static const struct sysrq_key_op sysrq_term_op = {
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.handler = sysrq_handle_term,
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.help_msg = "terminate-all-tasks(e)",
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.action_msg = "Terminate All Tasks",
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.enable_mask = SYSRQ_ENABLE_SIGNAL,
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};
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static void moom_callback(struct work_struct *ignored)
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{
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const gfp_t gfp_mask = GFP_KERNEL;
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struct oom_control oc = {
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.zonelist = node_zonelist(first_memory_node, gfp_mask),
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.nodemask = NULL,
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.memcg = NULL,
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.gfp_mask = gfp_mask,
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.order = -1,
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};
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mutex_lock(&oom_lock);
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if (!out_of_memory(&oc))
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pr_info("OOM request ignored. No task eligible\n");
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mutex_unlock(&oom_lock);
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}
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static DECLARE_WORK(moom_work, moom_callback);
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static void sysrq_handle_moom(int key)
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{
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schedule_work(&moom_work);
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}
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static const struct sysrq_key_op sysrq_moom_op = {
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.handler = sysrq_handle_moom,
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.help_msg = "memory-full-oom-kill(f)",
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.action_msg = "Manual OOM execution",
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.enable_mask = SYSRQ_ENABLE_SIGNAL,
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};
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static void sysrq_handle_thaw(int key)
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{
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emergency_thaw_all();
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}
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static const struct sysrq_key_op sysrq_thaw_op = {
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.handler = sysrq_handle_thaw,
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.help_msg = "thaw-filesystems(j)",
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.action_msg = "Emergency Thaw of all frozen filesystems",
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.enable_mask = SYSRQ_ENABLE_SIGNAL,
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};
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static void sysrq_handle_kill(int key)
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{
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send_sig_all(SIGKILL);
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console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
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}
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static const struct sysrq_key_op sysrq_kill_op = {
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.handler = sysrq_handle_kill,
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.help_msg = "kill-all-tasks(i)",
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.action_msg = "Kill All Tasks",
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.enable_mask = SYSRQ_ENABLE_SIGNAL,
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};
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static void sysrq_handle_unrt(int key)
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{
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normalize_rt_tasks();
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}
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static const struct sysrq_key_op sysrq_unrt_op = {
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.handler = sysrq_handle_unrt,
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.help_msg = "nice-all-RT-tasks(n)",
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.action_msg = "Nice All RT Tasks",
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.enable_mask = SYSRQ_ENABLE_RTNICE,
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};
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/* Key Operations table and lock */
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static DEFINE_SPINLOCK(sysrq_key_table_lock);
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static const struct sysrq_key_op *sysrq_key_table[62] = {
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&sysrq_loglevel_op, /* 0 */
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&sysrq_loglevel_op, /* 1 */
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&sysrq_loglevel_op, /* 2 */
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&sysrq_loglevel_op, /* 3 */
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&sysrq_loglevel_op, /* 4 */
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&sysrq_loglevel_op, /* 5 */
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&sysrq_loglevel_op, /* 6 */
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&sysrq_loglevel_op, /* 7 */
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&sysrq_loglevel_op, /* 8 */
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&sysrq_loglevel_op, /* 9 */
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/*
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* a: Don't use for system provided sysrqs, it is handled specially on
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* sparc and will never arrive.
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*/
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NULL, /* a */
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&sysrq_reboot_op, /* b */
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&sysrq_crash_op, /* c */
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&sysrq_showlocks_op, /* d */
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&sysrq_term_op, /* e */
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&sysrq_moom_op, /* f */
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/* g: May be registered for the kernel debugger */
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NULL, /* g */
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NULL, /* h - reserved for help */
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&sysrq_kill_op, /* i */
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#ifdef CONFIG_BLOCK
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&sysrq_thaw_op, /* j */
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#else
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NULL, /* j */
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#endif
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&sysrq_SAK_op, /* k */
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#ifdef CONFIG_SMP
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&sysrq_showallcpus_op, /* l */
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#else
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NULL, /* l */
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#endif
|
|
&sysrq_showmem_op, /* m */
|
|
&sysrq_unrt_op, /* n */
|
|
/* o: This will often be registered as 'Off' at init time */
|
|
NULL, /* o */
|
|
&sysrq_showregs_op, /* p */
|
|
&sysrq_show_timers_op, /* q */
|
|
&sysrq_unraw_op, /* r */
|
|
&sysrq_sync_op, /* s */
|
|
&sysrq_showstate_op, /* t */
|
|
&sysrq_mountro_op, /* u */
|
|
/* v: May be registered for frame buffer console restore */
|
|
NULL, /* v */
|
|
&sysrq_showstate_blocked_op, /* w */
|
|
/* x: May be registered on mips for TLB dump */
|
|
/* x: May be registered on ppc/powerpc for xmon */
|
|
/* x: May be registered on sparc64 for global PMU dump */
|
|
NULL, /* x */
|
|
/* 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 */
|
|
NULL, /* R */
|
|
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)
|
|
{
|
|
int retval;
|
|
|
|
if ((key >= '0') && (key <= '9'))
|
|
retval = key - '0';
|
|
else if ((key >= 'a') && (key <= 'z'))
|
|
retval = key + 10 - 'a';
|
|
else if ((key >= 'A') && (key <= 'Z'))
|
|
retval = key + 36 - 'A';
|
|
else
|
|
retval = -1;
|
|
return retval;
|
|
}
|
|
|
|
/*
|
|
* get and put functions for the table, exposed to modules.
|
|
*/
|
|
static const struct sysrq_key_op *__sysrq_get_key_op(int key)
|
|
{
|
|
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];
|
|
|
|
return op_p;
|
|
}
|
|
|
|
static void __sysrq_put_key_op(int key, const struct sysrq_key_op *op_p)
|
|
{
|
|
int i = sysrq_key_table_key2index(key);
|
|
|
|
if (i != -1)
|
|
sysrq_key_table[i] = op_p;
|
|
}
|
|
|
|
void __handle_sysrq(int key, bool check_mask)
|
|
{
|
|
const struct sysrq_key_op *op_p;
|
|
int orig_log_level;
|
|
int orig_suppress_printk;
|
|
int i;
|
|
|
|
orig_suppress_printk = suppress_printk;
|
|
suppress_printk = 0;
|
|
|
|
rcu_sysrq_start();
|
|
rcu_read_lock();
|
|
printk_prefer_direct_enter();
|
|
/*
|
|
* 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.
|
|
*/
|
|
orig_log_level = console_loglevel;
|
|
console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
|
|
|
|
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_info("%s\n", op_p->action_msg);
|
|
console_loglevel = orig_log_level;
|
|
op_p->handler(key);
|
|
} else {
|
|
pr_info("This sysrq operation is disabled.\n");
|
|
console_loglevel = orig_log_level;
|
|
}
|
|
} else {
|
|
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]) {
|
|
int j;
|
|
|
|
for (j = 0; sysrq_key_table[i] !=
|
|
sysrq_key_table[j]; j++)
|
|
;
|
|
if (j != i)
|
|
continue;
|
|
pr_cont("%s ", sysrq_key_table[i]->help_msg);
|
|
}
|
|
}
|
|
pr_cont("\n");
|
|
console_loglevel = orig_log_level;
|
|
}
|
|
printk_prefer_direct_exit();
|
|
rcu_read_unlock();
|
|
rcu_sysrq_end();
|
|
|
|
suppress_printk = orig_suppress_printk;
|
|
}
|
|
|
|
void handle_sysrq(int key)
|
|
{
|
|
if (sysrq_on())
|
|
__handle_sysrq(key, true);
|
|
}
|
|
EXPORT_SYMBOL(handle_sysrq);
|
|
|
|
#ifdef CONFIG_INPUT
|
|
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 */
|
|
|
|
struct sysrq_state {
|
|
struct input_handle handle;
|
|
struct work_struct reinject_work;
|
|
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;
|
|
|
|
/* reset sequence handling */
|
|
bool reset_canceled;
|
|
bool reset_requested;
|
|
unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)];
|
|
int reset_seq_len;
|
|
int reset_seq_cnt;
|
|
int reset_seq_version;
|
|
struct timer_list keyreset_timer;
|
|
};
|
|
|
|
#define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */
|
|
static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX];
|
|
static unsigned int sysrq_reset_seq_len;
|
|
static unsigned int sysrq_reset_seq_version = 1;
|
|
|
|
static void sysrq_parse_reset_sequence(struct sysrq_state *state)
|
|
{
|
|
int i;
|
|
unsigned short key;
|
|
|
|
state->reset_seq_cnt = 0;
|
|
|
|
for (i = 0; i < sysrq_reset_seq_len; i++) {
|
|
key = sysrq_reset_seq[i];
|
|
|
|
if (key == KEY_RESERVED || key > KEY_MAX)
|
|
break;
|
|
|
|
__set_bit(key, state->reset_keybit);
|
|
state->reset_seq_len++;
|
|
|
|
if (test_bit(key, state->key_down))
|
|
state->reset_seq_cnt++;
|
|
}
|
|
|
|
/* Disable reset until old keys are not released */
|
|
state->reset_canceled = state->reset_seq_cnt != 0;
|
|
|
|
state->reset_seq_version = sysrq_reset_seq_version;
|
|
}
|
|
|
|
static void sysrq_do_reset(struct timer_list *t)
|
|
{
|
|
struct sysrq_state *state = from_timer(state, t, keyreset_timer);
|
|
|
|
state->reset_requested = true;
|
|
|
|
orderly_reboot();
|
|
}
|
|
|
|
static void sysrq_handle_reset_request(struct sysrq_state *state)
|
|
{
|
|
if (state->reset_requested)
|
|
__handle_sysrq(sysrq_xlate[KEY_B], false);
|
|
|
|
if (sysrq_reset_downtime_ms)
|
|
mod_timer(&state->keyreset_timer,
|
|
jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms));
|
|
else
|
|
sysrq_do_reset(&state->keyreset_timer);
|
|
}
|
|
|
|
static void sysrq_detect_reset_sequence(struct sysrq_state *state,
|
|
unsigned int code, int value)
|
|
{
|
|
if (!test_bit(code, state->reset_keybit)) {
|
|
/*
|
|
* Pressing any key _not_ in reset sequence cancels
|
|
* the reset sequence. Also cancelling the timer in
|
|
* case additional keys were pressed after a reset
|
|
* has been requested.
|
|
*/
|
|
if (value && state->reset_seq_cnt) {
|
|
state->reset_canceled = true;
|
|
del_timer(&state->keyreset_timer);
|
|
}
|
|
} else if (value == 0) {
|
|
/*
|
|
* Key release - all keys in the reset sequence need
|
|
* to be pressed and held for the reset timeout
|
|
* to hold.
|
|
*/
|
|
del_timer(&state->keyreset_timer);
|
|
|
|
if (--state->reset_seq_cnt == 0)
|
|
state->reset_canceled = false;
|
|
} else if (value == 1) {
|
|
/* key press, not autorepeat */
|
|
if (++state->reset_seq_cnt == state->reset_seq_len &&
|
|
!state->reset_canceled) {
|
|
sysrq_handle_reset_request(state);
|
|
}
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_OF
|
|
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) {
|
|
pr_debug("No sysrq node found");
|
|
return;
|
|
}
|
|
|
|
/* Reset in case a __weak definition was present */
|
|
sysrq_reset_seq_len = 0;
|
|
|
|
of_property_for_each_u32(np, "keyset", prop, p, key) {
|
|
if (key == KEY_RESERVED || key > KEY_MAX ||
|
|
sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX)
|
|
break;
|
|
|
|
sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key;
|
|
}
|
|
|
|
/* Get reset timeout if any. */
|
|
of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
|
|
|
|
of_node_put(np);
|
|
}
|
|
#else
|
|
static void sysrq_of_get_keyreset_config(void)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
static void sysrq_reinject_alt_sysrq(struct work_struct *work)
|
|
{
|
|
struct sysrq_state *sysrq =
|
|
container_of(work, struct sysrq_state, reinject_work);
|
|
struct input_handle *handle = &sysrq->handle;
|
|
unsigned int alt_code = sysrq->alt_use;
|
|
|
|
if (sysrq->need_reinject) {
|
|
/* we do not want the assignment to be reordered */
|
|
sysrq->reinjecting = true;
|
|
mb();
|
|
|
|
/* Simulate press and release of Alt + SysRq */
|
|
input_inject_event(handle, EV_KEY, alt_code, 1);
|
|
input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
|
|
input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
|
|
|
|
input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
|
|
input_inject_event(handle, EV_KEY, alt_code, 0);
|
|
input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
|
|
|
|
mb();
|
|
sysrq->reinjecting = false;
|
|
}
|
|
}
|
|
|
|
static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
|
|
unsigned int code, int value)
|
|
{
|
|
bool was_active = sysrq->active;
|
|
bool suppress;
|
|
|
|
switch (code) {
|
|
|
|
case KEY_LEFTALT:
|
|
case KEY_RIGHTALT:
|
|
if (!value) {
|
|
/* One of ALTs is being released */
|
|
if (sysrq->active && code == sysrq->alt_use)
|
|
sysrq->active = false;
|
|
|
|
sysrq->alt = KEY_RESERVED;
|
|
|
|
} else if (value != 2) {
|
|
sysrq->alt = code;
|
|
sysrq->need_reinject = false;
|
|
}
|
|
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.
|
|
*/
|
|
sysrq->need_reinject = true;
|
|
}
|
|
|
|
/*
|
|
* Pretend that sysrq was never pressed at all. This
|
|
* is needed to properly handle KGDB which will try
|
|
* to release all keys after exiting debugger. If we
|
|
* do not clear key bit it KGDB will end up sending
|
|
* release events for Alt and SysRq, potentially
|
|
* triggering print screen function.
|
|
*/
|
|
if (sysrq->active)
|
|
clear_bit(KEY_SYSRQ, sysrq->handle.dev->key);
|
|
|
|
break;
|
|
|
|
default:
|
|
if (sysrq->active && value && value != 2) {
|
|
unsigned char c = sysrq_xlate[code];
|
|
|
|
sysrq->need_reinject = false;
|
|
if (sysrq->shift_use != KEY_RESERVED)
|
|
c = toupper(c);
|
|
__handle_sysrq(c, true);
|
|
}
|
|
break;
|
|
}
|
|
|
|
suppress = sysrq->active;
|
|
|
|
if (!sysrq->active) {
|
|
|
|
/*
|
|
* See if reset sequence has changed since the last time.
|
|
*/
|
|
if (sysrq->reset_seq_version != sysrq_reset_seq_version)
|
|
sysrq_parse_reset_sequence(sysrq);
|
|
|
|
/*
|
|
* If we are not suppressing key presses keep track of
|
|
* keyboard state so we can release keys that have been
|
|
* pressed before entering SysRq mode.
|
|
*/
|
|
if (value)
|
|
set_bit(code, sysrq->key_down);
|
|
else
|
|
clear_bit(code, sysrq->key_down);
|
|
|
|
if (was_active)
|
|
schedule_work(&sysrq->reinject_work);
|
|
|
|
/* Check for reset sequence */
|
|
sysrq_detect_reset_sequence(sysrq, code, value);
|
|
|
|
} else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) {
|
|
/*
|
|
* Pass on release events for keys that was pressed before
|
|
* entering SysRq mode.
|
|
*/
|
|
suppress = false;
|
|
}
|
|
|
|
return suppress;
|
|
}
|
|
|
|
static bool sysrq_filter(struct input_handle *handle,
|
|
unsigned int type, unsigned int code, int value)
|
|
{
|
|
struct sysrq_state *sysrq = handle->private;
|
|
bool suppress;
|
|
|
|
/*
|
|
* Do not filter anything if we are in the process of re-injecting
|
|
* Alt+SysRq combination.
|
|
*/
|
|
if (sysrq->reinjecting)
|
|
return false;
|
|
|
|
switch (type) {
|
|
|
|
case EV_SYN:
|
|
suppress = false;
|
|
break;
|
|
|
|
case EV_KEY:
|
|
suppress = sysrq_handle_keypress(sysrq, code, value);
|
|
break;
|
|
|
|
default:
|
|
suppress = sysrq->active;
|
|
break;
|
|
}
|
|
|
|
return suppress;
|
|
}
|
|
|
|
static int sysrq_connect(struct input_handler *handler,
|
|
struct input_dev *dev,
|
|
const struct input_device_id *id)
|
|
{
|
|
struct sysrq_state *sysrq;
|
|
int error;
|
|
|
|
sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
|
|
if (!sysrq)
|
|
return -ENOMEM;
|
|
|
|
INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
|
|
|
|
sysrq->handle.dev = dev;
|
|
sysrq->handle.handler = handler;
|
|
sysrq->handle.name = "sysrq";
|
|
sysrq->handle.private = sysrq;
|
|
timer_setup(&sysrq->keyreset_timer, sysrq_do_reset, 0);
|
|
|
|
error = input_register_handle(&sysrq->handle);
|
|
if (error) {
|
|
pr_err("Failed to register input sysrq handler, error %d\n",
|
|
error);
|
|
goto err_free;
|
|
}
|
|
|
|
error = input_open_device(&sysrq->handle);
|
|
if (error) {
|
|
pr_err("Failed to open input device, error %d\n", error);
|
|
goto err_unregister;
|
|
}
|
|
|
|
return 0;
|
|
|
|
err_unregister:
|
|
input_unregister_handle(&sysrq->handle);
|
|
err_free:
|
|
kfree(sysrq);
|
|
return error;
|
|
}
|
|
|
|
static void sysrq_disconnect(struct input_handle *handle)
|
|
{
|
|
struct sysrq_state *sysrq = handle->private;
|
|
|
|
input_close_device(handle);
|
|
cancel_work_sync(&sysrq->reinject_work);
|
|
del_timer_sync(&sysrq->keyreset_timer);
|
|
input_unregister_handle(handle);
|
|
kfree(sysrq);
|
|
}
|
|
|
|
/*
|
|
* We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
|
|
* keyboards have SysRq key predefined and so user may add it to keymap
|
|
* later, but we expect all such keyboards to have left alt.
|
|
*/
|
|
static const struct input_device_id sysrq_ids[] = {
|
|
{
|
|
.flags = INPUT_DEVICE_ID_MATCH_EVBIT |
|
|
INPUT_DEVICE_ID_MATCH_KEYBIT,
|
|
.evbit = { [BIT_WORD(EV_KEY)] = BIT_MASK(EV_KEY) },
|
|
.keybit = { [BIT_WORD(KEY_LEFTALT)] = BIT_MASK(KEY_LEFTALT) },
|
|
},
|
|
{ },
|
|
};
|
|
|
|
static struct input_handler sysrq_handler = {
|
|
.filter = sysrq_filter,
|
|
.connect = sysrq_connect,
|
|
.disconnect = sysrq_disconnect,
|
|
.name = "sysrq",
|
|
.id_table = sysrq_ids,
|
|
};
|
|
|
|
static inline void sysrq_register_handler(void)
|
|
{
|
|
int error;
|
|
|
|
sysrq_of_get_keyreset_config();
|
|
|
|
error = input_register_handler(&sysrq_handler);
|
|
if (error)
|
|
pr_err("Failed to register input handler, error %d", error);
|
|
}
|
|
|
|
static inline void sysrq_unregister_handler(void)
|
|
{
|
|
input_unregister_handler(&sysrq_handler);
|
|
}
|
|
|
|
static int sysrq_reset_seq_param_set(const char *buffer,
|
|
const struct kernel_param *kp)
|
|
{
|
|
unsigned long val;
|
|
int error;
|
|
|
|
error = kstrtoul(buffer, 0, &val);
|
|
if (error < 0)
|
|
return error;
|
|
|
|
if (val > KEY_MAX)
|
|
return -EINVAL;
|
|
|
|
*((unsigned short *)kp->arg) = val;
|
|
sysrq_reset_seq_version++;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct kernel_param_ops param_ops_sysrq_reset_seq = {
|
|
.get = param_get_ushort,
|
|
.set = sysrq_reset_seq_param_set,
|
|
};
|
|
|
|
#define param_check_sysrq_reset_seq(name, p) \
|
|
__param_check(name, p, unsigned short)
|
|
|
|
/*
|
|
* not really modular, but the easiest way to keep compat with existing
|
|
* bootargs behaviour is to continue using module_param here.
|
|
*/
|
|
module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
|
|
&sysrq_reset_seq_len, 0644);
|
|
|
|
module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644);
|
|
|
|
#else
|
|
|
|
static inline void sysrq_register_handler(void)
|
|
{
|
|
}
|
|
|
|
static inline void sysrq_unregister_handler(void)
|
|
{
|
|
}
|
|
|
|
#endif /* CONFIG_INPUT */
|
|
|
|
int sysrq_toggle_support(int enable_mask)
|
|
{
|
|
bool was_enabled = sysrq_on();
|
|
|
|
sysrq_enabled = enable_mask;
|
|
|
|
if (was_enabled != sysrq_on()) {
|
|
if (sysrq_on())
|
|
sysrq_register_handler();
|
|
else
|
|
sysrq_unregister_handler();
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(sysrq_toggle_support);
|
|
|
|
static int __sysrq_swap_key_ops(int key, const struct sysrq_key_op *insert_op_p,
|
|
const struct sysrq_key_op *remove_op_p)
|
|
{
|
|
int retval;
|
|
|
|
spin_lock(&sysrq_key_table_lock);
|
|
if (__sysrq_get_key_op(key) == remove_op_p) {
|
|
__sysrq_put_key_op(key, insert_op_p);
|
|
retval = 0;
|
|
} else {
|
|
retval = -1;
|
|
}
|
|
spin_unlock(&sysrq_key_table_lock);
|
|
|
|
/*
|
|
* A concurrent __handle_sysrq either got the old op or the new op.
|
|
* Wait for it to go away before returning, so the code for an old
|
|
* op is not freed (eg. on module unload) while it is in use.
|
|
*/
|
|
synchronize_rcu();
|
|
|
|
return retval;
|
|
}
|
|
|
|
int register_sysrq_key(int 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, const struct sysrq_key_op *op_p)
|
|
{
|
|
return __sysrq_swap_key_ops(key, NULL, op_p);
|
|
}
|
|
EXPORT_SYMBOL(unregister_sysrq_key);
|
|
|
|
#ifdef CONFIG_PROC_FS
|
|
/*
|
|
* writing 'C' to /proc/sysrq-trigger is like sysrq-C
|
|
*/
|
|
static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
if (count) {
|
|
char c;
|
|
|
|
if (get_user(c, buf))
|
|
return -EFAULT;
|
|
__handle_sysrq(c, false);
|
|
}
|
|
|
|
return count;
|
|
}
|
|
|
|
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,
|
|
&sysrq_trigger_proc_ops))
|
|
pr_err("Failed to register proc interface\n");
|
|
}
|
|
|
|
#else
|
|
|
|
static inline void sysrq_init_procfs(void)
|
|
{
|
|
}
|
|
|
|
#endif /* CONFIG_PROC_FS */
|
|
|
|
static int __init sysrq_init(void)
|
|
{
|
|
sysrq_init_procfs();
|
|
|
|
if (sysrq_on())
|
|
sysrq_register_handler();
|
|
|
|
return 0;
|
|
}
|
|
device_initcall(sysrq_init);
|