[PATCH] Notify page fault call chain for sparc64
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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@ -31,6 +31,40 @@
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#include <asm/kdebug.h>
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#include <asm/mmu_context.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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* To debug kernel to catch accesses to certain virtual/physical addresses.
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* Mode = 0 selects physical watchpoints, mode = 1 selects virtual watchpoints.
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@ -263,7 +297,7 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
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fault_code = get_thread_fault_code();
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if (notify_die(DIE_PAGE_FAULT, "page_fault", regs,
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if (notify_page_fault(DIE_PAGE_FAULT, "page_fault", regs,
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fault_code, 0, SIGSEGV) == NOTIFY_STOP)
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return;
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@ -17,6 +17,8 @@ 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 sparc64die_chain;
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extern void bad_trap(struct pt_regs *, long);
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