/* -*- 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> * based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz> * * (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com> * overhauled to use key registration * based upon discusions in irc://irc.openprojects.net/#kernelnewbies */ #include <linux/sched.h> #include <linux/interrupt.h> #include <linux/mm.h> #include <linux/fs.h> #include <linux/tty.h> #include <linux/mount.h> #include <linux/kdev_t.h> #include <linux/major.h> #include <linux/reboot.h> #include <linux/sysrq.h> #include <linux/kbd_kern.h> #include <linux/proc_fs.h> #include <linux/nmi.h> #include <linux/quotaops.h> #include <linux/perf_event.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/suspend.h> #include <linux/writeback.h> #include <linux/buffer_head.h> /* for fsync_bdev() */ #include <linux/swap.h> #include <linux/spinlock.h> #include <linux/vt_kern.h> #include <linux/workqueue.h> #include <linux/hrtimer.h> #include <linux/oom.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; int sysrq_on(void) { 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) { 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"); return 1; } __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); console_loglevel = i; } static struct sysrq_key_op sysrq_loglevel_op = { .handler = sysrq_handle_loglevel, .help_msg = "loglevel(0-9)", .action_msg = "Changing Loglevel", .enable_mask = SYSRQ_ENABLE_LOG, }; #ifdef CONFIG_VT static void sysrq_handle_SAK(int key, struct tty_struct *tty) { struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work; schedule_work(SAK_work); } static struct sysrq_key_op sysrq_SAK_op = { .handler = sysrq_handle_SAK, .help_msg = "saK", .action_msg = "SAK", .enable_mask = SYSRQ_ENABLE_KEYBOARD, }; #else #define sysrq_SAK_op (*(struct sysrq_key_op *)0) #endif #ifdef CONFIG_VT static void sysrq_handle_unraw(int key, struct tty_struct *tty) { struct kbd_struct *kbd = &kbd_table[fg_console]; if (kbd) kbd->kbdmode = default_utf8 ? VC_UNICODE : VC_XLATE; } static struct sysrq_key_op sysrq_unraw_op = { .handler = sysrq_handle_unraw, .help_msg = "unRaw", .action_msg = "Keyboard mode set to system default", .enable_mask = SYSRQ_ENABLE_KEYBOARD, }; #else #define sysrq_unraw_op (*(struct sysrq_key_op *)0) #endif /* CONFIG_VT */ static void sysrq_handle_crash(int key, struct tty_struct *tty) { char *killer = NULL; panic_on_oops = 1; /* force panic */ wmb(); *killer = 1; } static struct sysrq_key_op sysrq_crash_op = { .handler = sysrq_handle_crash, .help_msg = "Crash", .action_msg = "Trigger a crash", .enable_mask = SYSRQ_ENABLE_DUMP, }; static void sysrq_handle_reboot(int key, struct tty_struct *tty) { lockdep_off(); local_irq_enable(); emergency_restart(); } static struct sysrq_key_op sysrq_reboot_op = { .handler = sysrq_handle_reboot, .help_msg = "reBoot", .action_msg = "Resetting", .enable_mask = SYSRQ_ENABLE_BOOT, }; static void sysrq_handle_sync(int key, struct tty_struct *tty) { emergency_sync(); } static struct sysrq_key_op sysrq_sync_op = { .handler = sysrq_handle_sync, .help_msg = "Sync", .action_msg = "Emergency Sync", .enable_mask = SYSRQ_ENABLE_SYNC, }; static void sysrq_handle_show_timers(int key, struct tty_struct *tty) { sysrq_timer_list_show(); } static 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, struct tty_struct *tty) { emergency_remount(); } static struct sysrq_key_op sysrq_mountro_op = { .handler = sysrq_handle_mountro, .help_msg = "Unmount", .action_msg = "Emergency Remount R/O", .enable_mask = SYSRQ_ENABLE_REMOUNT, }; #ifdef CONFIG_LOCKDEP static void sysrq_handle_showlocks(int key, struct tty_struct *tty) { debug_show_all_locks(); } static 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 *)0) #endif #ifdef CONFIG_SMP static DEFINE_SPINLOCK(show_lock); static void showacpu(void *dummy) { unsigned long flags; /* Idle CPUs have no interesting backtrace. */ if (idle_cpu(smp_processor_id())) return; spin_lock_irqsave(&show_lock, flags); printk(KERN_INFO "CPU%d:\n", smp_processor_id()); show_stack(NULL, NULL); spin_unlock_irqrestore(&show_lock, flags); } static void sysrq_showregs_othercpus(struct work_struct *dummy) { smp_call_function(showacpu, NULL, 0); } static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus); static void sysrq_handle_showallcpus(int key, struct tty_struct *tty) { /* * Fall back to the workqueue based printing if the * backtrace printing did not succeed or the * architecture has no support for it: */ if (!trigger_all_cpu_backtrace()) { struct pt_regs *regs = get_irq_regs(); if (regs) { printk(KERN_INFO "CPU%d:\n", smp_processor_id()); show_regs(regs); } schedule_work(&sysrq_showallcpus); } } static 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, }; #endif static void sysrq_handle_showregs(int key, struct tty_struct *tty) { struct pt_regs *regs = get_irq_regs(); if (regs) show_regs(regs); perf_event_print_debug(); } static 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, struct tty_struct *tty) { show_state(); } static 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, struct tty_struct *tty) { show_state_filter(TASK_UNINTERRUPTIBLE); } static struct sysrq_key_op sysrq_showstate_blocked_op = { .handler = sysrq_handle_showstate_blocked, .help_msg = "show-blocked-tasks(W)", .action_msg = "Show Blocked State", .enable_mask = SYSRQ_ENABLE_DUMP, }; #ifdef CONFIG_TRACING #include <linux/ftrace.h> static void sysrq_ftrace_dump(int key, struct tty_struct *tty) { ftrace_dump(); } static 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 *)0) #endif static void sysrq_handle_showmem(int key, struct tty_struct *tty) { show_mem(); } static struct sysrq_key_op sysrq_showmem_op = { .handler = sysrq_handle_showmem, .help_msg = "show-memory-usage(M)", .action_msg = "Show Memory", .enable_mask = SYSRQ_ENABLE_DUMP, }; /* * Signal sysrq helper function. Sends a signal to all user processes. */ static void send_sig_all(int sig) { struct task_struct *p; for_each_process(p) { if (p->mm && !is_global_init(p)) /* Not swapper, init nor kernel thread */ force_sig(sig, p); } } static void sysrq_handle_term(int key, struct tty_struct *tty) { send_sig_all(SIGTERM); console_loglevel = 8; } static struct sysrq_key_op sysrq_term_op = { .handler = sysrq_handle_term, .help_msg = "terminate-all-tasks(E)", .action_msg = "Terminate All Tasks", .enable_mask = SYSRQ_ENABLE_SIGNAL, }; static void moom_callback(struct work_struct *ignored) { out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0, NULL); } static DECLARE_WORK(moom_work, moom_callback); static void sysrq_handle_moom(int key, struct tty_struct *tty) { schedule_work(&moom_work); } static struct sysrq_key_op sysrq_moom_op = { .handler = sysrq_handle_moom, .help_msg = "memory-full-oom-kill(F)", .action_msg = "Manual OOM execution", .enable_mask = SYSRQ_ENABLE_SIGNAL, }; #ifdef CONFIG_BLOCK static void sysrq_handle_thaw(int key, struct tty_struct *tty) { emergency_thaw_all(); } static 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, }; #endif static void sysrq_handle_kill(int key, struct tty_struct *tty) { send_sig_all(SIGKILL); console_loglevel = 8; } static 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, struct tty_struct *tty) { normalize_rt_tasks(); } static 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, }; /* Key Operations table and lock */ static DEFINE_SPINLOCK(sysrq_key_table_lock); static struct sysrq_key_op *sysrq_key_table[36] = { &sysrq_loglevel_op, /* 0 */ &sysrq_loglevel_op, /* 1 */ &sysrq_loglevel_op, /* 2 */ &sysrq_loglevel_op, /* 3 */ &sysrq_loglevel_op, /* 4 */ &sysrq_loglevel_op, /* 5 */ &sysrq_loglevel_op, /* 6 */ &sysrq_loglevel_op, /* 7 */ &sysrq_loglevel_op, /* 8 */ &sysrq_loglevel_op, /* 9 */ /* * a: Don't use for system provided sysrqs, it is handled specially on * sparc and will never arrive. */ NULL, /* a */ &sysrq_reboot_op, /* b */ &sysrq_crash_op, /* c & ibm_emac driver debug */ &sysrq_showlocks_op, /* d */ &sysrq_term_op, /* e */ &sysrq_moom_op, /* f */ /* g: May be registered for the kernel debugger */ 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 */ 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 ppc/powerpc for xmon */ NULL, /* x */ /* y: May be registered on sparc64 for global register dump */ NULL, /* y */ &sysrq_ftrace_dump_op, /* 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 retval = -1; return retval; } /* * get and put functions for the table, exposed to modules. */ struct sysrq_key_op *__sysrq_get_key_op(int key) { 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, struct sysrq_key_op *op_p) { int i = sysrq_key_table_key2index(key); if (i != -1) sysrq_key_table[i] = op_p; } /* * This is the non-locking version of handle_sysrq. It must/can only be called * by sysrq key handlers, as they are inside of the lock */ void __handle_sysrq(int key, struct tty_struct *tty, int check_mask) { struct sysrq_key_op *op_p; int orig_log_level; int i; unsigned long flags; spin_lock_irqsave(&sysrq_key_table_lock, flags); /* * 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 = 7; printk(KERN_INFO "SysRq : "); 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)) { printk("%s\n", op_p->action_msg); console_loglevel = orig_log_level; op_p->handler(key, tty); } else { printk("This sysrq operation is disabled.\n"); } } else { printk("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; printk("%s ", sysrq_key_table[i]->help_msg); } } printk("\n"); console_loglevel = orig_log_level; } spin_unlock_irqrestore(&sysrq_key_table_lock, flags); } /* * This function is called by the keyboard handler when SysRq is pressed * and any other keycode arrives. */ void handle_sysrq(int key, struct tty_struct *tty) { if (sysrq_on()) __handle_sysrq(key, tty, 1); } EXPORT_SYMBOL(handle_sysrq); static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p, struct sysrq_key_op *remove_op_p) { int retval; unsigned long flags; spin_lock_irqsave(&sysrq_key_table_lock, flags); if (__sysrq_get_key_op(key) == remove_op_p) { __sysrq_put_key_op(key, insert_op_p); retval = 0; } else { retval = -1; } spin_unlock_irqrestore(&sysrq_key_table_lock, flags); return retval; } int register_sysrq_key(int key, 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) { 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, NULL, 0); } return count; } static const struct file_operations proc_sysrq_trigger_operations = { .write = write_sysrq_trigger, }; static int __init sysrq_init(void) { proc_create("sysrq-trigger", S_IWUSR, NULL, &proc_sysrq_trigger_operations); return 0; } module_init(sysrq_init); #endif