linux-stable.git/kernel/kprobes.c, branch linux-2.6.27.y

kprobes: Fix locking imbalance in kretprobes

2009-05-02T17:24:37+00:00

commit f02b8624fedca39886b0eef770dca70c2f0749b3 upstream.

Fix locking imbalance in kretprobes:

=====================================
[ BUG: bad unlock balance detected! ]
-------------------------------------
kthreadd/2 is trying to release lock (&rp->lock) at:
[] pre_handler_kretprobe+0xea/0xf4
but there are no more locks to release!

other info that might help us debug this:
1 lock held by kthreadd/2:
 #0:  (rcu_read_lock){..--}, at: [] __atomic_notifier_call_chain+0x0/0x5a

stack backtrace:
Pid: 2, comm: kthreadd Not tainted 2.6.29-rc8 #1
Call Trace:
 [] ? printk+0xf/0x17
 [] ? pre_handler_kretprobe+0xea/0xf4
 [] print_unlock_inbalance_bug+0xc3/0xce
 [] ? clocksource_read+0x7/0xa
 [] ? getnstimeofday+0x5f/0xf6
 [] ? register_lock_class+0x17/0x293
 [] ? mark_lock+0x1e/0x30b
 [] ? tick_dev_program_event+0x4a/0xbc
 [] ? __slab_alloc+0xa5/0x415
 [] ? pre_handler_kretprobe+0x28/0xf4
 [] ? pre_handler_kretprobe+0xea/0xf4
 [] lock_release_non_nested+0xa4/0x1a5
 [] ? pre_handler_kretprobe+0xea/0xf4
 [] lock_release+0x141/0x166
 [] _spin_unlock_irqrestore+0x19/0x50
 [] pre_handler_kretprobe+0xea/0xf4
 [] kprobe_exceptions_notify+0x1c9/0x43e
 [] notifier_call_chain+0x26/0x48
 [] __atomic_notifier_call_chain+0x37/0x5a
 [] ? __atomic_notifier_call_chain+0x0/0x5a
 [] atomic_notifier_call_chain+0xc/0xe
 [] notify_die+0x2d/0x2f
 [] do_int3+0x1f/0x71
 [] int3+0x2c/0x34
 [] ? do_fork+0x1/0x288
 [] ? kernel_thread+0x71/0x79
 [] ? kthread+0x0/0x60
 [] ? kthread+0x0/0x60
 [] ? kernel_thread_helper+0x0/0x10
 [] kthreadd+0xac/0x148
 [] ? kthreadd+0x0/0x148
 [] kernel_thread_helper+0x7/0x10

Signed-off-by: Ananth N Mavinakayanahalli 
Tested-by: Bharata B Rao 
Cc: Masami Hiramatsu 
Cc: Jim Keniston 
Cc: Linus Torvalds 
Cc: Andrew Morton 
LKML-Reference: <20090318113621.GB4129@in.ibm.com>
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

kprobes: remove redundant config check

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

I noticed that there's a CONFIG_KPROBES check inside kernel/kprobes.c,
which is redundant.

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

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

kernel/kprobes.c: Made kprobe_blacklist static.

2008-07-10T17:13:51+00:00

Signed-off-by: Daniel Guilak 
Signed-off-by: Linus Torvalds

kprobes: fix error checking of batch registration

2008-06-13T01:05:40+00:00

Fix error checking routine to catch an error which occurs in first
__register_*probe().

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

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: fix a null pointer bug in register_kretprobe()

2008-03-05T00:35:19+00:00

Fix a bug in regiseter_kretprobe() which does not check rp->kp.symbol_name ==
NULL before calling kprobe_lookup_name.

For maintainability, this introduces kprobe_addr helper function which
resolves addr field.  It is used by register_kprobe and register_kretprobe.

Signed-off-by: Masami Hiramatsu 
Cc: Ananth N Mavinakayanahalli 
Cc: Jim Keniston 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds