1bd858a507
Currently in the do_page_fault() code path, we call notify_die(DIE_PAGE_FAULT, ...) to notify the page fault. Since notify_die() is highly overloaded, this page fault notification is currently being sent to all the components registered with register_die_notification() which uses the same die_chain to loop for all the registered components which is unnecessary. In order to optimize the do_page_fault() code path, this critical page fault notification is now moved to different call chain and the test results showed great improvements. And the kprobes which is interested in this notifications, now registers onto this new call chain only when it need to, i.e Kprobes now registers for page fault notification only when their are an active probes and unregisters from this page fault notification when no probes are active. I have incorporated all the feedback given by Ananth and Keith and everyone, and thanks for all the review feedback. This patch: 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>
60 lines
1.3 KiB
C
60 lines
1.3 KiB
C
#ifndef _X86_64_KDEBUG_H
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#define _X86_64_KDEBUG_H 1
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#include <linux/notifier.h>
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struct pt_regs;
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struct die_args {
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struct pt_regs *regs;
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const char *str;
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long err;
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int trapnr;
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int signr;
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};
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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 die_chain;
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/* Grossly misnamed. */
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enum die_val {
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DIE_OOPS = 1,
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DIE_INT3,
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DIE_DEBUG,
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DIE_PANIC,
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DIE_NMI,
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DIE_DIE,
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DIE_NMIWATCHDOG,
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DIE_KERNELDEBUG,
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DIE_TRAP,
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DIE_GPF,
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DIE_CALL,
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DIE_NMI_IPI,
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DIE_PAGE_FAULT,
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};
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static inline int notify_die(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(&die_chain, val, &args);
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}
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extern int printk_address(unsigned long address);
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extern void die(const char *,struct pt_regs *,long);
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extern void __die(const char *,struct pt_regs *,long);
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extern void show_registers(struct pt_regs *regs);
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extern void dump_pagetable(unsigned long);
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extern unsigned long oops_begin(void);
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extern void oops_end(unsigned long);
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#endif
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