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remarkable-linux/drivers/char/sysrq.c
David S. Miller 93dae5b70e sparc64: Add global register dumping facility. 
When a cpu really is stuck in the kernel, it can be often
impossible to figure out which cpu is stuck where.  The
worst case is when the stuck cpu has interrupts disabled.

Therefore, implement a global cpu state capture that uses
SMP message interrupts which are not disabled by the
normal IRQ enable/disable APIs of the kernel.

As long as we can get a sysrq 'y' to the kernel, we can
get a dump.  Even if the console interrupt cpu is wedged,
we can trigger it from userspace using /proc/sysrq-trigger

The output is made compact so that this facility is more
useful on high cpu count systems, which is where this
facility will likely find itself the most useful :)

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-05-20 00:33:45 -07:00

536 lines
13 KiB
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/* -*- 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/quotaops.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/kexec.h>
#include <linux/irq.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 = "loglevel0-8",
.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 */
#ifdef CONFIG_KEXEC
static void sysrq_handle_crashdump(int key, struct tty_struct *tty)
{
crash_kexec(get_irq_regs());
}
static struct sysrq_key_op sysrq_crashdump_op = {
.handler = sysrq_handle_crashdump,
.help_msg = "Crashdump",
.action_msg = "Trigger a crashdump",
.enable_mask = SYSRQ_ENABLE_DUMP,
};
#else
#define sysrq_crashdump_op (*(struct sysrq_key_op *)0)
#endif
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 Pending Timers",
};
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, 0);
}
static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
static void sysrq_handle_showallcpus(int key, struct tty_struct *tty)
{
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 = "aLlcpus",
.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);
}
static struct sysrq_key_op sysrq_showregs_op = {
.handler = sysrq_handle_showregs,
.help_msg = "showPc",
.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 = "showTasks",
.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",
.action_msg = "Show Blocked State",
.enable_mask = SYSRQ_ENABLE_DUMP,
};
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 = "showMem",
.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 = "tErm",
.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);
}
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 = "Full",
.action_msg = "Manual OOM execution",
};
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",
.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",
.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_crashdump_op, /* c & ibm_emac driver debug */
&sysrq_showlocks_op, /* d */
&sysrq_term_op, /* e */
&sysrq_moom_op, /* f */
/* g: May be registered by ppc for kgdb */
NULL, /* g */
NULL, /* h */
&sysrq_kill_op, /* i */
NULL, /* j */
&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 at init time by SMP VOYAGER */
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 */
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
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);
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);
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