linux-sg2042/include/linux/sysrq.h

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/* -*- linux-c -*-
*
* $Id: sysrq.h,v 1.3 1997/07/17 11:54:33 mj Exp $
*
* Linux Magic System Request Key Hacks
*
* (c) 1997 Martin Mares <mj@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
*/
#ifndef _LINUX_SYSRQ_H
#define _LINUX_SYSRQ_H
struct pt_regs;
struct tty_struct;
/* Possible values of bitmask for enabling sysrq functions */
/* 0x0001 is reserved for enable everything */
#define SYSRQ_ENABLE_LOG 0x0002
#define SYSRQ_ENABLE_KEYBOARD 0x0004
#define SYSRQ_ENABLE_DUMP 0x0008
#define SYSRQ_ENABLE_SYNC 0x0010
#define SYSRQ_ENABLE_REMOUNT 0x0020
#define SYSRQ_ENABLE_SIGNAL 0x0040
#define SYSRQ_ENABLE_BOOT 0x0080
#define SYSRQ_ENABLE_RTNICE 0x0100
struct sysrq_key_op {
IRQ: Maintain regs pointer globally rather than passing to IRQ handlers Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells <dhowells@redhat.com> (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
2006-10-05 21:55:46 +08:00
void (*handler)(int, struct tty_struct *);
char *help_msg;
char *action_msg;
int enable_mask;
};
#ifdef CONFIG_MAGIC_SYSRQ
extern int sysrq_on(void);
/*
* Do not use this one directly:
*/
extern int __sysrq_enabled;
/* Generic SysRq interface -- you may call it from any device driver, supplying
* ASCII code of the key, pointer to registers and kbd/tty structs (if they
* are available -- else NULL's).
*/
void handle_sysrq(int key, struct tty_struct *tty);
void __handle_sysrq(int key, struct tty_struct *tty, int check_mask);
int register_sysrq_key(int key, struct sysrq_key_op *op);
int unregister_sysrq_key(int key, struct sysrq_key_op *op);
struct sysrq_key_op *__sysrq_get_key_op(int key);
#else
static inline int sysrq_on(void)
{
return 0;
}
static inline int __reterr(void)
{
return -EINVAL;
}
static inline void handle_sysrq(int key, struct tty_struct *tty)
{
}
#define register_sysrq_key(ig,nore) __reterr()
#define unregister_sysrq_key(ig,nore) __reterr()
#endif
#endif /* _LINUX_SYSRQ_H */