linux-toradex.git/include/linux/kprobes.h, branch v2.6.27.14

kprobes: improve kretprobe scalability with hashed locking

2008-07-25T17:53:30+00:00

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: Srinivasa DS 
Signed-off-by: Jim Keniston 
Acked-by: Ananth N Mavinakayanahalli 
Cc: Anil S Keshavamurthy 
Cc: David S. Miller 
Cc: Masami Hiramatsu 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kprobes: enable clean usage of get_kprobe

2008-06-23T20:10:57+00:00

Allow clean use of get_kprobe() outside of core kprobe code. Ftrace makes use
of get_kprobe to identify probes installed on mcount call-sites.

Signed-off-by: Abhishek Sagar 
Acked-by: Ananth N Mavinakayanahalli 
Cc: Masami Hiramatsu 
Cc: jkenisto@us.ibm.com
Cc: Steven Rostedt 
Signed-off-by: Ingo Molnar

kprobes: add (un)register_jprobes for batch registration

2008-04-28T15:58:32+00:00

Introduce unregister_/register_jprobes() for jprobe batch registration.

Signed-off-by: Masami Hiramatsu 
Cc: Ananth N Mavinakayanahalli 
Cc: Jim Keniston 
Cc: Prasanna S Panchamukhi 
Cc: Shaohua Li 
Cc: David Miller 
Cc: "Frank Ch. Eigler" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kprobes: add (un)register_kretprobes for batch registration

2008-04-28T15:58:32+00:00

Introduce unregister_/register_kretprobes() for kretprobe batch registration.

Signed-off-by: Masami Hiramatsu 
Cc: Ananth N Mavinakayanahalli 
Cc: Jim Keniston 
Cc: Prasanna S Panchamukhi 
Cc: Shaohua Li 
Cc: David Miller 
Cc: "Frank Ch. Eigler" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kprobes: add (un)register_kprobes for batch registration

2008-04-28T15:58:32+00:00

Introduce unregister_/register_kprobes() for kprobe batch registration.  This
can reduce waiting time for synchronized_sched() when a lot of probes have to
be unregistered at once.

Signed-off-by: Masami Hiramatsu 
Cc: Ananth N Mavinakayanahalli 
Cc: Jim Keniston 
Cc: Prasanna S Panchamukhi 
Cc: Shaohua Li 
Cc: David Miller 
Cc: "Frank Ch. Eigler" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kprobes: prevent probing of preempt_schedule()

2008-04-28T15:58:32+00:00

Prohibit users from probing preempt_schedule().  One way of prohibiting the
user from probing functions is by marking such functions with __kprobes.  But
this method doesn't work for those functions, which are already marked to
different section like preempt_schedule() (belongs to __sched section).  So we
use blacklist approach to refuse user from probing these functions.

In blacklist approach we populate the blacklisted function's starting address
and its size in kprobe_blacklist structure.  Then we verify the user specified
address against start and end of the blacklisted function.  So any attempt to
register probe on blacklisted functions will be rejected.

[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Srinivasa DS 
Signed-off-by: Ananth N Mavinakayanahalli 
Signed-off-by: Jim Keniston 
Cc: Dave Hansen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Kprobes: indicate kretprobe support in Kconfig

2008-03-05T00:35:11+00:00

Add CONFIG_HAVE_KRETPROBES to the arch//Kconfig file for relevant
architectures with kprobes support.  This facilitates easy handling of
in-kernel modules (like samples/kprobes/kretprobe_example.c) that depend on
kretprobes being present in the kernel.

Thanks to Sam Ravnborg for helping make the patch more lean.

Per Mathieu's suggestion, added CONFIG_KRETPROBES and fixed up dependencies.

Signed-off-by: Ananth N Mavinakayanahalli 
Acked-by: Mathieu Desnoyers 
Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kprobes: kretprobe user entry-handler

2008-02-06T18:41:11+00:00

Provide support to add an optional user defined callback to be run at
function entry of a kretprobe'd function.  Also modify the kprobe smoke
tests to include an entry-handler during the kretprobe sanity test.

Signed-off-by: Abhishek Sagar 
Cc: Prasanna S Panchamukhi 
Cc: Ananth N Mavinakayanahalli 
Cc: Anil S Keshavamurthy 
Acked-by: Jim Keniston 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

x86: kprobes: add kprobes smoke tests that run on boot

2008-01-30T12:32:53+00:00

Here is a quick and naive smoke test for kprobes. This is intended to
just verify if some unrelated change broke the *probes subsystem. It is
self contained, architecture agnostic and isn't of any great use by itself.

This needs to be built in the kernel and runs a basic set of tests to
verify if kprobes, jprobes and kretprobes run fine on the kernel. In case
of an error, it'll print out a message with a "BUG" prefix.

This is a start; we intend to add more tests to this bucket over time.

Thanks to Jim Keniston and Masami Hiramatsu for comments and suggestions.

Tested on x86 (32/64) and powerpc.

Signed-off-by: Ananth N Mavinakayanahalli 
Acked-by: Masami Hiramatsu 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar

kprobes: support kretprobe blacklist

2007-10-16T16:43:10+00:00

Introduce architecture dependent kretprobe blacklists to prohibit users
from inserting return probes on the function in which kprobes can be
inserted but kretprobes can not.

This patch also removes "__kprobes" mark from "__switch_to" on x86_64 and
registers "__switch_to" to the blacklist on x86-64, because that mark is to
prohibit user from inserting only kretprobe.

Signed-off-by: Masami Hiramatsu 
Cc: Prasanna S Panchamukhi 
Acked-by: Ananth N Mavinakayanahalli 
Cc: Anil S Keshavamurthy 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds