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Commit d98f8f05188b45168db43df8ddc9feeb0b1cd512

Authored by Anil S Keshavamurthy
Committed by Linus Torvalds
1 parent 4f9e87c045
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

[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>

Showing 2 changed files with 37 additions and 1 deletions Side-by-side Diff

arch/sparc64/mm/fault.c
Diff comments   View file @ d98f8f0
... ... @@ -31,6 +31,40 @@
31 31 #include <asm/kdebug.h>
32 32 #include <asm/mmu_context.h>
33 33  
  34 +#ifdef CONFIG_KPROBES
  35 +ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);
  36 +
  37 +/* Hook to register for page fault notifications */
  38 +int register_page_fault_notifier(struct notifier_block *nb)
  39 +{
  40 + return atomic_notifier_chain_register(&notify_page_fault_chain, nb);
  41 +}
  42 +
  43 +int unregister_page_fault_notifier(struct notifier_block *nb)
  44 +{
  45 + return atomic_notifier_chain_unregister(&notify_page_fault_chain, nb);
  46 +}
  47 +
  48 +static inline int notify_page_fault(enum die_val val, const char *str,
  49 + struct pt_regs *regs, long err, int trap, int sig)
  50 +{
  51 + struct die_args args = {
  52 + .regs = regs,
  53 + .str = str,
  54 + .err = err,
  55 + .trapnr = trap,
  56 + .signr = sig
  57 + };
  58 + return atomic_notifier_call_chain(&notify_page_fault_chain, val, &args);
  59 +}
  60 +#else
  61 +static inline int notify_page_fault(enum die_val val, const char *str,
  62 + struct pt_regs *regs, long err, int trap, int sig)
  63 +{
  64 + return NOTIFY_DONE;
  65 +}
  66 +#endif
  67 +
34 68 /*
35 69 * To debug kernel to catch accesses to certain virtual/physical addresses.
36 70 * Mode = 0 selects physical watchpoints, mode = 1 selects virtual watchpoints.
... ... @@ -263,7 +297,7 @@
263 297  
264 298 fault_code = get_thread_fault_code();
265 299  
266   - if (notify_die(DIE_PAGE_FAULT, "page_fault", regs,
  300 + if (notify_page_fault(DIE_PAGE_FAULT, "page_fault", regs,
267 301 fault_code, 0, SIGSEGV) == NOTIFY_STOP)
268 302 return;
269 303  
include/asm-sparc64/kdebug.h
Diff comments   View file @ d98f8f0
... ... @@ -17,6 +17,8 @@
17 17  
18 18 extern int register_die_notifier(struct notifier_block *);
19 19 extern int unregister_die_notifier(struct notifier_block *);
  20 +extern int register_page_fault_notifier(struct notifier_block *);
  21 +extern int unregister_page_fault_notifier(struct notifier_block *);
20 22 extern struct atomic_notifier_head sparc64die_chain;
21 23  
22 24 extern void bad_trap(struct pt_regs *, long);