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  1. 26 2月, 2010 2 次提交
    • M
      kprobes: Jump optimization sysctl interface · b2be84df
      由 Masami Hiramatsu 提交于 
      Add /proc/sys/debug/kprobes-optimization sysctl which enables
and disables kprobes jump optimization on the fly for debugging.

Changes in v7:
 - Remove ctl_name = CTL_UNNUMBERED for upstream compatibility.

Changes in v6:
- Update comments and coding style.
Signed-off-by: NMasami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Anders Kaseorg <andersk@ksplice.com>
Cc: Tim Abbott <tabbott@ksplice.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
LKML-Reference: <20100225133415.6725.8274.stgit@localhost6.localdomain6>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      b2be84df
    • M
      kprobes: Introduce kprobes jump optimization · afd66255
      由 Masami Hiramatsu 提交于 
      Introduce kprobes jump optimization arch-independent parts.
Kprobes uses breakpoint instruction for interrupting execution
flow, on some architectures, it can be replaced by a jump
instruction and interruption emulation code. This gains kprobs'
performance drastically.

To enable this feature, set CONFIG_OPTPROBES=y (default y if the
arch supports OPTPROBE).

Changes in v9:
 - Fix a bug to optimize probe when enabling.
 - Check nearby probes can be optimize/unoptimize when disarming/arming
   kprobes, instead of registering/unregistering. This will help
   kprobe-tracer because most of probes on it are usually disabled.

Changes in v6:
 - Cleanup coding style for readability.
 - Add comments around get/put_online_cpus().

Changes in v5:
 - Use get_online_cpus()/put_online_cpus() for avoiding text_mutex
   deadlock.
Signed-off-by: NMasami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Anders Kaseorg <andersk@ksplice.com>
Cc: Tim Abbott <tabbott@ksplice.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
LKML-Reference: <20100225133407.6725.81992.stgit@localhost6.localdomain6>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      afd66255
  3. 16 9月, 2009 1 次提交
  5. 27 8月, 2009 1 次提交
    • F
      tracing/kprobes: Dump the culprit kprobe in case of kprobe recursion · 24851d24
      由 Frederic Weisbecker 提交于 
      Kprobes can enter into a probing recursion, ie: a kprobe that does an
endless loop because one of its core mechanism function used during
probing is also probed itself.

This patch helps pinpointing the kprobe that raised such recursion
by dumping it and raising a BUG instead of a warning (we also disarm
the kprobe to try avoiding recursion in BUG itself). Having a BUG
instead of a warning stops the stacktrace in the right place and
doesn't pollute the logs with hundreds of traces that eventually end
up in a stack overflow.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
      24851d24
  7. 07 4月, 2009 3 次提交
  9. 21 2月, 2009 1 次提交
    • I
      x86, mm, kprobes: fault.c, simplify notify_page_fault() · b1801812
      由 Ingo Molnar 提交于 
      Impact: cleanup

Remove an #ifdef from notify_page_fault(). The function still
compiles to nothing in the !CONFIG_KPROBES case.

Introduce kprobes_built_in() and kprobe_fault_handler() helpers
to allow this - they returns 0 if !CONFIG_KPROBES.

No code changed:

   text	   data	    bss	    dec	    hex	filename
   4618	     32	     24	   4674	   1242	fault.o.before
   4618	     32	     24	   4674	   1242	fault.o.after

Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      b1801812
  11. 30 1月, 2009 1 次提交
  13. 07 1月, 2009 2 次提交
  15. 14 10月, 2008 1 次提交
  17. 26 7月, 2008 1 次提交
    • S
      kprobes: improve kretprobe scalability with hashed locking · ef53d9c5
      由 Srinivasa D S 提交于 
      Currently list of kretprobe instances are stored in kretprobe object (as
used_instances,free_instances) and in kretprobe hash table.  We have one
global kretprobe lock to serialise the access to these lists.  This causes
only one kretprobe handler to execute at a time.  Hence affects system
performance, particularly on SMP systems and when return probe is set on
lot of functions (like on all systemcalls).

Solution proposed here gives fine-grain locks that performs better on SMP
system compared to present kretprobe implementation.

Solution:

 1) Instead of having one global lock to protect kretprobe instances
    present in kretprobe object and kretprobe hash table.  We will have
    two locks, one lock for protecting kretprobe hash table and another
    lock for kretporbe object.

 2) We hold lock present in kretprobe object while we modify kretprobe
    instance in kretprobe object and we hold per-hash-list lock while
    modifying kretprobe instances present in that hash list.  To prevent
    deadlock, we never grab a per-hash-list lock while holding a kretprobe
    lock.

 3) We can remove used_instances from struct kretprobe, as we can
    track used instances of kretprobe instances using kretprobe hash
    table.

Time duration for kernel compilation ("make -j 8") on a 8-way ppc64 system
with return probes set on all systemcalls looks like this.

cacheline              non-cacheline             Un-patched kernel
aligned patch 	       aligned patch
===============================================================================
real    9m46.784s       9m54.412s                  10m2.450s
user    40m5.715s       40m7.142s                  40m4.273s
sys     2m57.754s       2m58.583s                  3m17.430s
===========================================================

Time duration for kernel compilation ("make -j 8) on the same system, when
kernel is not probed.
=========================
real    9m26.389s
user    40m8.775s
sys     2m7.283s
=========================
Signed-off-by: NSrinivasa DS <srinivasa@in.ibm.com>
Signed-off-by: NJim Keniston <jkenisto@us.ibm.com>
Acked-by: NAnanth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      ef53d9c5
  19. 24 6月, 2008 1 次提交
  21. 28 4月, 2008 4 次提交
  23. 05 3月, 2008 1 次提交
  25. 07 2月, 2008 1 次提交
  27. 30 1月, 2008 1 次提交
  29. 17 10月, 2007 1 次提交
  31. 20 7月, 2007 3 次提交
  33. 09 5月, 2007 4 次提交
  35. 08 12月, 2006 1 次提交
    • M
      [PATCH] kprobes: enable booster on the preemptible kernel · b4c6c34a
      由 Masami Hiramatsu 提交于 
      When we are unregistering a kprobe-booster, we can't release its
instruction buffer immediately on the preemptive kernel, because some
processes might be preempted on the buffer.  The freeze_processes() and
thaw_processes() functions can clean most of processes up from the buffer.
There are still some non-frozen threads who have the PF_NOFREEZE flag.  If
those threads are sleeping (not preempted) at the known place outside the
buffer, we can ensure safety of freeing.

However, the processing of this check routine takes a long time.  So, this
patch introduces the garbage collection mechanism of insn_slot.  It also
introduces the "dirty" flag to free_insn_slot because of efficiency.

The "clean" instruction slots (dirty flag is cleared) are released
immediately.  But the "dirty" slots which are used by boosted kprobes, are
marked as garbages.  collect_garbage_slots() will be invoked to release
"dirty" slots if there are more than INSNS_PER_PAGE garbage slots or if
there are no unused slots.

Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "bibo,mao" <bibo.mao@intel.com>
Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Cc: Yumiko Sugita <yumiko.sugita.yf@hitachi.com>
Cc: Satoshi Oshima <soshima@redhat.com>
Cc: Hideo Aoki <haoki@redhat.com>
Signed-off-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      b4c6c34a
  37. 02 10月, 2006 2 次提交
  39. 26 4月, 2006 1 次提交
  41. 23 3月, 2006 1 次提交
  43. 12 1月, 2006 1 次提交
    • K
      [PATCH] kprobes: fix unloading of self probed module · df019b1d
      由 Keshavamurthy Anil S 提交于 
      When a kprobes modules is written in such a way that probes are inserted on
itself, then unload of that moudle was not possible due to reference
couning on the same module.

The below patch makes a check and incrementes the module refcount only if
it is not a self probed module.

We need to allow modules to probe themself for kprobes performance
measurements

This patch has been tested on several x86_64, ppc64 and IA64 architectures.

Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      df019b1d
  45. 11 1月, 2006 3 次提交
  47. 13 12月, 2005 2 次提交