include/linux/sysrq.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /* -*- linux-c -*-
   3  *
   4  *      $Id: sysrq.h,v 1.3 1997/07/17 11:54:33 mj Exp $
   5  *
   6  *      Linux Magic System Request Key Hacks
   7  *
   8  *      (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
   9  *
  10  *      (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
  11  *      overhauled to use key registration
  12  *      based upon discusions in irc://irc.openprojects.net/#kernelnewbies
  13  */
  14
  15 #ifndef _LINUX_SYSRQ_H
  16 #define _LINUX_SYSRQ_H
  17
  18 #include <linux/errno.h>
  19 #include <linux/types.h>
  20
  21 /* Possible values of bitmask for enabling sysrq functions */
  22 /* 0x0001 is reserved for enable everything */
  23 #define SYSRQ_ENABLE_LOG        0x0002
  24 #define SYSRQ_ENABLE_KEYBOARD   0x0004
  25 #define SYSRQ_ENABLE_DUMP       0x0008
  26 #define SYSRQ_ENABLE_SYNC       0x0010
  27 #define SYSRQ_ENABLE_REMOUNT    0x0020
  28 #define SYSRQ_ENABLE_SIGNAL     0x0040
  29 #define SYSRQ_ENABLE_BOOT       0x0080
  30 #define SYSRQ_ENABLE_RTNICE     0x0100
  31
  32 #define SYSRQ_DISABLE_USERSPACE 0x00010000
  33
  34 struct sysrq_key_op {
  35         void (*handler)(int);
  36         char *help_msg;
  37         char *action_msg;
  38         int enable_mask;
  39 };
  40
  41 #ifdef CONFIG_MAGIC_SYSRQ
  42
  43 /* Generic SysRq interface -- you may call it from any device driver, supplying
  44  * ASCII code of the key, pointer to registers and kbd/tty structs (if they
  45  * are available -- else NULL's).
  46  */
  47
  48 #define SYSRQ_FROM_KERNEL       0x0001
  49 #define SYSRQ_FROM_PROC         0x0002
  50 #define SYSRQ_FROM_SYNTHETIC    0x0004
  51
  52 void handle_sysrq(int key);
  53 void __handle_sysrq(int key, unsigned int from);
  54 int register_sysrq_key(int key, struct sysrq_key_op *op);
  55 int unregister_sysrq_key(int key, struct sysrq_key_op *op);
  56 struct sysrq_key_op *__sysrq_get_key_op(int key);
  57
  58 int sysrq_toggle_support(int enable_mask);
  59
  60 #else
  61
  62 static inline void handle_sysrq(int key)
  63 {
  64 }
  65
  66 static inline void __handle_sysrq(int key, bool check_mask)
  67 {
  68 }
  69
  70 static inline int register_sysrq_key(int key, struct sysrq_key_op *op)
  71 {
  72         return -EINVAL;
  73 }
  74
  75 static inline int unregister_sysrq_key(int key, struct sysrq_key_op *op)
  76 {
  77         return -EINVAL;
  78 }
  79
  80 #endif
  81
  82 #endif /* _LINUX_SYSRQ_H */