[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: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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2 changed files with 37 additions and 1 deletions
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@ -40,6 +40,40 @@
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#include <asm/kdebug.h>
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#include <asm/siginfo.h>
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#ifdef CONFIG_KPROBES
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ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);
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/* Hook to register for page fault notifications */
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int register_page_fault_notifier(struct notifier_block *nb)
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{
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return atomic_notifier_chain_register(¬ify_page_fault_chain, nb);
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}
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int unregister_page_fault_notifier(struct notifier_block *nb)
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{
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return atomic_notifier_chain_unregister(¬ify_page_fault_chain, nb);
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}
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static inline int notify_page_fault(enum die_val val, const char *str,
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struct pt_regs *regs, long err, int trap, int sig)
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{
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struct die_args args = {
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.regs = regs,
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.str = str,
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.err = err,
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.trapnr = trap,
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.signr = sig
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};
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return atomic_notifier_call_chain(¬ify_page_fault_chain, val, &args);
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}
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#else
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static inline int notify_page_fault(enum die_val val, const char *str,
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struct pt_regs *regs, long err, int trap, int sig)
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{
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return NOTIFY_DONE;
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}
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#endif
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/*
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* Check whether the instruction at regs->nip is a store using
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* an update addressing form which will update r1.
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@ -142,7 +176,7 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
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is_write = error_code & ESR_DST;
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#endif /* CONFIG_4xx || CONFIG_BOOKE */
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if (notify_die(DIE_PAGE_FAULT, "page_fault", regs, error_code,
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if (notify_page_fault(DIE_PAGE_FAULT, "page_fault", regs, error_code,
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11, SIGSEGV) == NOTIFY_STOP)
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return 0;
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@ -18,6 +18,8 @@ struct die_args {
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extern int register_die_notifier(struct notifier_block *);
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extern int unregister_die_notifier(struct notifier_block *);
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extern int register_page_fault_notifier(struct notifier_block *);
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extern int unregister_page_fault_notifier(struct notifier_block *);
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extern struct atomic_notifier_head powerpc_die_chain;
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/* Grossly misnamed. */
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