Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 4f9e87c0 authored by Anil S Keshavamurthy's avatar Anil S Keshavamurthy Committed by Linus Torvalds
Browse files

[PATCH] Notify page fault call chain for powerpc 



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 ae9a5b85

arch/powerpc/mm/fault.c

+35 −1
Original line number Diff line number Diff line
@@ -40,6 +40,40 @@ 
#include <asm/kdebug.h>

#include <asm/siginfo.h>



#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



/*

 * Check whether the instruction at regs->nip is a store using

 * an update addressing form which will update r1.
@@ -142,7 +176,7 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address, 
	is_write = error_code & ESR_DST;

#endif /* CONFIG_4xx || CONFIG_BOOKE */



	if (notify_die(DIE_PAGE_FAULT, "page_fault", regs, error_code,

	if (notify_page_fault(DIE_PAGE_FAULT, "page_fault", regs, error_code,

				11, SIGSEGV) == NOTIFY_STOP)

		return 0;

include/asm-powerpc/kdebug.h

+2 −0
Original line number Diff line number Diff line
@@ -18,6 +18,8 @@ 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 powerpc_die_chain;



/* Grossly misnamed. */