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Commit ae9a5b85 authored by Anil S Keshavamurthy's avatar Anil S Keshavamurthy Committed by Linus Torvalds
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[PATCH] Notify page fault call chain for ia64 



Overloading of page fault notification with the notify_die() has performance
issues(since the only interested components for page fault is kprobes and/or
kdb) and hence this patch introduces the new notifier call chain exclusively
for page fault notifications their by avoiding notifying unnecessary
components in the do_page_fault() code path.

Signed-off-by: default avatarAnil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent b71b5b65

arch/ia64/mm/fault.c

+35 −1
Original line number Diff line number Diff line
@@ -19,6 +19,40 @@ 


extern void die (char *, struct pt_regs *, long);



#ifdef CONFIG_KPROBES

ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);



/* Hook to register for page fault notifications */

int register_page_fault_notifier(struct notifier_block *nb)

{

	return atomic_notifier_chain_register(&notify_page_fault_chain, nb);

}



int unregister_page_fault_notifier(struct notifier_block *nb)

{

	return atomic_notifier_chain_unregister(&notify_page_fault_chain, nb);

}



static inline int notify_page_fault(enum die_val val, const char *str,

			struct pt_regs *regs, long err, int trap, int sig)

{

	struct die_args args = {

		.regs = regs,

		.str = str,

		.err = err,

		.trapnr = trap,

		.signr = sig

	};

	return atomic_notifier_call_chain(&notify_page_fault_chain, val, &args);

}

#else

static inline int notify_page_fault(enum die_val val, const char *str,

			struct pt_regs *regs, long err, int trap, int sig)

{

	return NOTIFY_DONE;

}

#endif



/*

 * Return TRUE if ADDRESS points at a page in the kernel's mapped segment

 * (inside region 5, on ia64) and that page is present.
@@ -84,7 +118,7 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re 
	/*

	 * This is to handle the kprobes on user space access instructions

	 */

	if (notify_die(DIE_PAGE_FAULT, "page fault", regs, code, TRAP_BRKPT,

	if (notify_page_fault(DIE_PAGE_FAULT, "page fault", regs, code, TRAP_BRKPT,

					SIGSEGV) == NOTIFY_STOP)

		return;

include/asm-ia64/kdebug.h

+2 −0
Original line number Diff line number Diff line
@@ -40,6 +40,8 @@ struct die_args { 


extern int register_die_notifier(struct notifier_block *);

extern int unregister_die_notifier(struct notifier_block *);

extern int register_page_fault_notifier(struct notifier_block *);

extern int unregister_page_fault_notifier(struct notifier_block *);

extern struct atomic_notifier_head ia64die_chain;



enum die_val {