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A pointer is dereferenced before it is null-checked.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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gconfig: only show scrollbars if needed (which is more user friendly):
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Patrick noticed that the initial scan of the semaphore operations logs
decrease and increase operations seperately, but then both cases are or'ed
together and decrease is never used. The attached patch removes the
decrease parameter - it shrinks sys_semtimedop() by 56 bytes.
Signed-Of-By: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Frame pointers are supposed to enable debuggers to reliably tell where a
call comes from. That is defeated by GCC's sibling call optimization (aka
tail recursion elimination).
This patch turns this optimization off when compiling with frame pointers.
Signed-Off-By: Matthias Urlichs <smurf@smurf.noris.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Avoid taking the tasklist_lock in sys_times if the process is single
threaded. In a NUMA system taking the tasklist_lock may cause a bouncing
cacheline if multiple independent processes continually call sys_times to
measure their performance.
Signed-off-by: Christoph Lameter <christoph@lameter.com>
Signed-off-by: Shai Fultheim <shai@scalex86.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch gets rid of some macro obfuscation from fs/eventpoll.c by
removing slab allocator wrappers and converting macros to static inline
functions.
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch improves write performance for the CD/DVD packet writing driver.
The logic for switching between reading and writing has been changed so
that streaming writes are no longer interrupted by read requests.
Signed-off-by: Peter Osterlund <petero2@telia.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch consolidates sys_fsync and sys_fdatasync.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Here's a small patch to improve the performance of mempool_alloc by only
initializing the wait queue when we're about to wait.
Signed-off-by: Benjamin LaHaise <benjamin.c.lahaise@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Adding quotation handling to rule_cc_o_c in scripts/Makefile.build as used
elsewhere.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Fix (in the architectures I'm actually building for) the UP definition of
per_cpu so that the cpu specified may be any expression, not just an
identifier or a suffix expression.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Fix a build problem when IDEFLOPPY_DEBUG_BUGS is turned off, and eliminate an
access to memory that is no longer allocated (causing systems to fail booting
when CONFIG_DEBUG_PAGEALLOC is turned on).
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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In ia64 kernel, the O_LARGEFILE flag is forced when opening a file. This
is problematic for execution of 32 bit processes, which are not largefile
aware, either by SW emulation or by HW execution.
For such processes, the problem is two-fold:
1) When trying to open a file that is larger than 4G
the operation should fail, but it's not
2) Writing to offset larger than 4G should fail, but
it's not
The proposed patch takes advantage of the way 32 bit processes are
identified in ia64 systems. Such processes have PER_LINUX32 for their
personality. With the patch, the ia64 kernel will not enforce the
O_LARGEFILE flag if the current process has PER_LINUX32 set. The behavior
for all other architectures remains unchanged.
Signed-off-by: Yoav Zach <yoav.zach@intel.com>
Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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kernel 2.6.12-rc2 adopted some code by Bjorn Helgaas supporting NetMos combo
controller cards. this implementation doesn't work for nm9855 based cards!
there are two reasons:
a) the module 'parport_pc' doesn't want to give the resonsibility for
the netmos_9855 to 'parport_serial' and can not handle the serial lines
-- trivial to fix...
http://lists.infradead.org/pipermail/linux-parport/2005-February/000250.html
http://lkml.org/lkml/2005/3/24/199 b) the support for the nm9855 in
'parport_serial' still doesn't work because of wrong assumptions about
the relevant BARs port address layout for this chip:
0000:00:09.0 Communication controller:
NetMos Technology PCI 9855
Multi-I/O Controller (rev 01)
(= 9710:9855)
Subsystem: LSI Logic / Symbios Logic 1P4S (= 1000:0014)
Flags: medium devsel, IRQ 177
I/O ports at a800 [size=8] (= parport)
I/O ports at a400 [size=8]
I/O ports at a000 [size=8] (= serial)
I/O ports at 9800 [size=8] (= serial)
I/O ports at 9400 [size=8] (= serial)
I/O ports at 9000 [size=16] (= serial)
the following patch will fix the problem.
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Small mod to shut off the xmit interrupt if we have nothing to transmit.
Signed-off-by: Patrick Gefre <pfg@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch removes O(n^2) super block loops in sync_inodes(),
sync_filesystems() etc. in favour of using __put_super_and_need_restart()
which I introduced earlier. We faced a noticably long freezes on sb
syncing when there are thousands of super blocks in the system.
Signed-Off-By: Kirill Korotaev <dev@sw.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch fixes recalc_sigpending() to work correctly with tasks which are
being freezed.
The problem is that freeze_processes() sets PF_FREEZE and TIF_SIGPENDING
flags on tasks, but recalc_sigpending() called from e.g.
sys_rt_sigtimedwait or any other kernel place will clear TIF_SIGPENDING due
to no pending signals queued and the tasks won't be freezed until it
recieves a real signal or freezed_processes() fail due to timeout.
Signed-Off-By: Kirill Korotaev <dev@sw.ru>
Signed-Off-By: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch fixes incorrect and bogus kernel messages that file-max limit
reached when the allocation fails
Signed-Off-By: Kirill Korotaev <dev@sw.ru>
Signed-Off-By: Denis Lunev <den@sw.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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In a duplicate of lookup_create in the af_unix code Al commented what's
going on nicely, so let's bring that over to lookup_create before the copy
is going away (I'll send a patch soon)
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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"Non-members are not allowed to post messages to this list. Blame the
original poster for cross-posting to subscriber-only mailing lists. "
Signed-off-by: Alexey Dobriyan <adobriyan@mail.ru>
Acked-by: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Henrik Grubbstrom noted:
The 2.6.10 ext3_get_parent attempts to use ext3_find_entry to look up the
entry "..", which fails for dx directories since ".." is not present in the
directory hash table. The patch below solves this by looking up the dotdot
entry in the dx_root block.
Typical symptoms of the above bug are intermittent claims by nfsd that
files or directories are missing on exported ext3 filesystems.
cf https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=3D150759 and
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=3D144556
ext3_get_parent() is IMHO the wrong place to fix this bug as it introduces
a lot of internals from htree into that function. Instead, I think this
should be fixed in ext3_find_entry() as in the below patch. This has the
added advantage that it works for any callers of ext3_find_entry() and not
just ext3_lookup_parent().
Signed-off-by: Andreas Dilger <adilger@clusterfs.com>
Signed-off-by: Henrik Grubbstrom <grubba@grubba.org>
Cc: <ext2-devel@lists.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Add a new `suid_dumpable' sysctl:
This value can be used to query and set the core dump mode for setuid
or otherwise protected/tainted binaries. The modes are
0 - (default) - traditional behaviour. Any process which has changed
privilege levels or is execute only will not be dumped
1 - (debug) - all processes dump core when possible. The core dump is
owned by the current user and no security is applied. This is intended
for system debugging situations only. Ptrace is unchecked.
2 - (suidsafe) - any binary which normally would not be dumped is dumped
readable by root only. This allows the end user to remove such a dump but
not access it directly. For security reasons core dumps in this mode will
not overwrite one another or other files. This mode is appropriate when
adminstrators are attempting to debug problems in a normal environment.
(akpm:
> > +EXPORT_SYMBOL(suid_dumpable);
>
> EXPORT_SYMBOL_GPL?
No problem to me.
> > if (current->euid == current->uid && current->egid == current->gid)
> > current->mm->dumpable = 1;
>
> Should this be SUID_DUMP_USER?
Actually the feedback I had from last time was that the SUID_ defines
should go because its clearer to follow the numbers. They can go
everywhere (and there are lots of places where dumpable is tested/used
as a bool in untouched code)
> Maybe this should be renamed to `dump_policy' or something. Doing that
> would help us catch any code which isn't using the #defines, too.
Fair comment. The patch was designed to be easy to maintain for Red Hat
rather than for merging. Changing that field would create a gigantic
diff because it is used all over the place.
)
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Presently either multiple kprobes or only one jprobe could be inserted.
This patch removes the above limitation and allows one jprobe and multiple
kprobes to coexist at the same address. However multiple jprobes cannot
coexist with multiple kprobes. Currently I am working on the prototype to
allow multiple jprobes coexist with multiple kprobes.
Signed-off-by: Ananth N Mavinakayanhalli <amavin@redhat.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch includes IA64 architecture specific changes(ported form i386) to
support temporary disarming on reentrancy of probes.
In case of reentrancy we single step without calling user handler.
Signed-of-by: Anil S Keshavamurth <anil.s.keshavamurthy@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch includes sparc64 architecture specific changes to support temporary
disarming on reentrancy of probes.
Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch includes ppc64 architecture specific changes to support temporary
disarming on reentrancy of probes.
Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch includes x86_64 architecture specific changes to support temporary
disarming on reentrancy of probes.
Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch includes i386 architecture specific changes to support temporary
disarming on reentrancy of probes.
Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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In situations where a kprobes handler calls a routine which has a probe on it,
then kprobes_handler() disarms the new probe forever. This patch removes the
above limitation by temporarily disarming the new probe. When the another
probe hits while handling the old probe, the kprobes_handler() saves previous
kprobes state and handles the new probe without calling the new kprobes
registered handlers. kprobe_post_handler() restores back the previous kprobes
state and the normal execution continues.
However on x86_64 architecture, re-rentrancy is provided only through
pre_handler(). If a routine having probe is referenced through
post_handler(), then the probes on that routine are disarmed forever, since
the exception stack is gets changed after the processor single steps the
instruction of the new probe.
This patch includes generic changes to support temporary disarming on
reentrancy of probes.
Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Once the jprobe instrumented function returns, it executes a jprobe_break
which is a break instruction with __IA64_JPROBE_BREAK value. The current
patch checks for this break value, before assuming that jprobe instrumented
function just completed.
The previous code was not checking for this value and that was a bug.
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>
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The current kprobes does not yet handle register kprobes on some of the
following kind of instruction which needs to be emulated in a special way.
1) mov r1=ip
2) chk -- Speculation check instruction
This patch attempts to fail register_kprobes() when user tries to insert
kprobes on the above kind of instruction.
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>
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The current Kprobes when patching the original instruction with the break
instruction tries to retain the original qualifying predicate(qp), however
for cmp.crel.ctype where ctype == unc, which is a special instruction
always needs to be executed irrespective of qp. Hence, if the instruction
we are patching is of this type, then we should not copy the original qp to
the break instruction, this is because we always want the break fault to
happen so that we can emulate the instruction.
This patch is based on the feedback given by David Mosberger
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>
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arch_prepare_kprobes() was doing lots of functionality
in just one single function. This patch
attempts to clean up arch_prepare_kprobes() by moving
specific sub task to the following (new)functions
1)valid_kprobe_addr() -->> validate the given kprobe address
2)get_kprobe_inst(slot..)->> Retrives the instruction for a given slot from the bundle
3)prepare_break_inst() -->> Prepares break instruction within the bundle
3a)update_kprobe_inst_flag()-->>Updates the internal flags, required
for proper emulation of the instruction at later
point in time.
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>
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Fix a bug where a kprobe still fires when the instruction is predicated
off. So given the p6=0, and we have an instruction like:
(p6) move loc1=0
we should not be triggering the kprobe. This is handled by carrying over
the qp section of the original instruction into the break instruction.
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Rusty Lynch <Rusty.lynch@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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A cleanup of the ia64 kprobes implementation such that all of the bundle
manipulation logic is concentrated in arch_prepare_kprobe().
With the current design for kprobes, the arch specific code only has a
chance to return failure inside the arch_prepare_kprobe() function.
This patch moves all of the work that was happening in arch_copy_kprobe()
and most of the work that was happening in arch_arm_kprobe() into
arch_prepare_kprobe(). By doing this we can add further robustness checks
in arch_arm_kprobe() and refuse to insert kprobes that will cause problems.
Signed-off-by: Rusty Lynch <Rusty.lynch@intel.com>
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>
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This patch is required to support kprobe on branch/call instructions.
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>
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This patch adds IA64 architecture specific JProbes support on top of Kprobes
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Rusty Lynch <Rusty.lynch@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This is an IA64 arch specific handling of Kprobes
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Rusty Lynch <Rusty.lynch@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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As many of you know that kprobes exist in the main line kernel for various
architecture including i386, x86_64, ppc64 and sparc64. Attached patches
following this mail are a port of Kprobes and Jprobes for IA64.
I have tesed this patches for kprobes and Jprobes and this seems to work fine.
I have tested this patch by inserting kprobes on various slots and various
templates including various types of branch instructions.
I have also tested this patch using the tool
http://marc.theaimsgroup.com/?l=linux-kernel&m=111657358022586&w=2 and the
kprobes for IA64 works great.
Here is list of TODO things and pathes for the same will appear soon.
1) Support kprobes on "mov r1=ip" type of instruction
2) Support Kprobes and Jprobes to exist on the same address
3) Support Return probes
3) Architecture independent cleanup of kprobes
This patch adds the kdebug die notification mechanism needed by Kprobes.
For break instruction on Branch type slot, imm21 is ignored and value
zero is placed in IIM register, hence we need to handle kprobes
for switch case zero.
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Rusty Lynch <Rusty.lynch@intel.com>
From: Rusty Lynch <rusty.lynch@intel.com>
At the point in traps.c where we recieve a break with a zero value, we can
not say if the break was a result of a kprobe or some other debug facility.
This simple patch changes the informational string to a more correct "break
0" value, and applies to the 2.6.12-rc2-mm2 tree with all the kprobes
patches that were just recently included for the next mm cut.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch moves the lock/unlock of the arch specific kprobe_flush_task()
to the non-arch specific kprobe_flusk_task().
Signed-off-by: Hien Nguyen <hien@us.ibm.com>
Acked-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The architecture independent code of the current kprobes implementation is
arming and disarming kprobes at registration time. The problem is that the
code is assuming that arming and disarming is a just done by a simple write
of some magic value to an address. This is problematic for ia64 where our
instructions look more like structures, and we can not insert break points
by just doing something like:
*p->addr = BREAKPOINT_INSTRUCTION;
The following patch to 2.6.12-rc4-mm2 adds two new architecture dependent
functions:
* void arch_arm_kprobe(struct kprobe *p)
* void arch_disarm_kprobe(struct kprobe *p)
and then adds the new functions for each of the architectures that already
implement kprobes (spar64/ppc64/i386/x86_64).
I thought arch_[dis]arm_kprobe was the most descriptive of what was really
happening, but each of the architectures already had a disarm_kprobe()
function that was really a "disarm and do some other clean-up items as
needed when you stumble across a recursive kprobe." So... I took the
liberty of changing the code that was calling disarm_kprobe() to call
arch_disarm_kprobe(), and then do the cleanup in the block of code dealing
with the recursive kprobe case.
So far this patch as been tested on i386, x86_64, and ppc64, but still
needs to be tested in sparc64.
Signed-off-by: Rusty Lynch <rusty.lynch@intel.com>
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>
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The following patch adds the x86_64 architecture specific implementation
for function return probes.
Function return probes is a mechanism built on top of kprobes that allows
a caller to register a handler to be called when a given function exits.
For example, to instrument the return path of sys_mkdir:
static int sys_mkdir_exit(struct kretprobe_instance *i, struct pt_regs *regs)
{
printk("sys_mkdir exited\n");
return 0;
}
static struct kretprobe return_probe = {
.handler = sys_mkdir_exit,
};
<inside setup function>
return_probe.kp.addr = (kprobe_opcode_t *) kallsyms_lookup_name("sys_mkdir");
if (register_kretprobe(&return_probe)) {
printk(KERN_DEBUG "Unable to register return probe!\n");
/* do error path */
}
<inside cleanup function>
unregister_kretprobe(&return_probe);
The way this works is that:
* At system initialization time, kernel/kprobes.c installs a kprobe
on a function called kretprobe_trampoline() that is implemented in
the arch/x86_64/kernel/kprobes.c (More on this later)
* When a return probe is registered using register_kretprobe(),
kernel/kprobes.c will install a kprobe on the first instruction of the
targeted function with the pre handler set to arch_prepare_kretprobe()
which is implemented in arch/x86_64/kernel/kprobes.c.
* arch_prepare_kretprobe() will prepare a kretprobe instance that stores:
- nodes for hanging this instance in an empty or free list
- a pointer to the return probe
- the original return address
- a pointer to the stack address
With all this stowed away, arch_prepare_kretprobe() then sets the return
address for the targeted function to a special trampoline function called
kretprobe_trampoline() implemented in arch/x86_64/kernel/kprobes.c
* The kprobe completes as normal, with control passing back to the target
function that executes as normal, and eventually returns to our trampoline
function.
* Since a kprobe was installed on kretprobe_trampoline() during system
initialization, control passes back to kprobes via the architecture
specific function trampoline_probe_handler() which will lookup the
instance in an hlist maintained by kernel/kprobes.c, and then call
the handler function.
* When trampoline_probe_handler() is done, the kprobes infrastructure
single steps the original instruction (in this case just a top), and
then calls trampoline_post_handler(). trampoline_post_handler() then
looks up the instance again, puts the instance back on the free list,
and then makes a long jump back to the original return instruction.
So to recap, to instrument the exit path of a function this implementation
will cause four interruptions:
- A breakpoint at the very beginning of the function allowing us to
switch out the return address
- A single step interruption to execute the original instruction that
we replaced with the break instruction (normal kprobe flow)
- A breakpoint in the trampoline function where our instrumented function
returned to
- A single step interruption to execute the original instruction that
we replaced with the break instruction (normal kprobe flow)
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch adds function-return probes to kprobes for the i386
architecture. This enables you to establish a handler to be run when a
function returns.
1. API
Two new functions are added to kprobes:
int register_kretprobe(struct kretprobe *rp);
void unregister_kretprobe(struct kretprobe *rp);
2. Registration and unregistration
2.1 Register
To register a function-return probe, the user populates the following
fields in a kretprobe object and calls register_kretprobe() with the
kretprobe address as an argument:
kp.addr - the function's address
handler - this function is run after the ret instruction executes, but
before control returns to the return address in the caller.
maxactive - The maximum number of instances of the probed function that
can be active concurrently. For example, if the function is non-
recursive and is called with a spinlock or mutex held, maxactive = 1
should be enough. If the function is non-recursive and can never
relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should
be enough. maxactive is used to determine how many kretprobe_instance
objects to allocate for this particular probed function. If maxactive <=
0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 *
NR_CPUS) else maxactive=NR_CPUS)
For example:
struct kretprobe rp;
rp.kp.addr = /* entrypoint address */
rp.handler = /*return probe handler */
rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */
register_kretprobe(&rp);
The following field may also be of interest:
nmissed - Initialized to zero when the function-return probe is
registered, and incremented every time the probed function is entered but
there is no kretprobe_instance object available for establishing the
function-return probe (i.e., because maxactive was set too low).
2.2 Unregister
To unregiter a function-return probe, the user calls
unregister_kretprobe() with the same kretprobe object as registered
previously. If a probed function is running when the return probe is
unregistered, the function will return as expected, but the handler won't
be run.
3. Limitations
3.1 This patch supports only the i386 architecture, but patches for
x86_64 and ppc64 are anticipated soon.
3.2 Return probes operates by replacing the return address in the stack
(or in a known register, such as the lr register for ppc). This may
cause __builtin_return_address(0), when invoked from the return-probed
function, to return the address of the return-probes trampoline.
3.3 This implementation uses the "Multiprobes at an address" feature in
2.6.12-rc3-mm3.
3.4 Due to a limitation in multi-probes, you cannot currently establish
a return probe and a jprobe on the same function. A patch to remove
this limitation is being tested.
This feature is required by SystemTap (http://sourceware.org/systemtap),
and reflects ideas contributed by several SystemTap developers, including
Will Cohen and Ananth Mavinakayanahalli.
Signed-off-by: Hien Nguyen <hien@us.ibm.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Use lookup_one_len instead of opencoding a simplified lookup using
lookup_hash with a fake hash.
Also there's no need anymore for the d_invalidate as we have a completely
valid dentry now.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Move some code duplicated in both callers into vfs_quota_on_mount
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jan Kara <jack@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Prevent recursive faults in do_exit() by leaving the task alone and wait
for reboot. This may allow a more graceful shutdown and possibly save the
original oops.
Signed-off-by: Alexander Nyberg <alexn@telia.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Various filesystem drivers have grown a get_dentry() function that's a
duplicate of lookup_one_len, except that it doesn't take a maximum length
argument and doesn't check for \0 or / in the passed in filename.
Switch all these places to use lookup_one_len.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Greg KH <greg@kroah.com>
Cc: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Patch to add check to get_chrdev_list and get_blkdev_list to prevent reads
of /proc/devices from spilling over the provided page if more than 4096
bytes of string data are generated from all the registered character and
block devices in a system
Signed-off-by: Neil Horman <nhorman@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch removes redundant VM_ClearReadHint from mm/madvice.c which was
left there by Prasanna's patch.
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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In kernel/sched.c the return value from preempt_count() is cast to an int.
That made sense when preempt_count was defined as different types on is not
needed and should go away. The patch removes the cast.
In kernel/timer.c the return value from preempt_count() is assigned to a
variable of type u32 and then that unsigned value is later compared to
preempt_count(). Since preempt_count() returns an int, an int is what
should be used to store its return value. Storing the result in an
unsigned 32bit integer made a tiny bit of sense back when preempt_count was
different types on different archs, but no more - let's not play signed vs
unsigned comparison games when we don't have to. The patch modifies the
code to use an int to hold the value. While I was around that bit of code
I also made two changes to a nearby (related) printk() - I modified it to
specify the loglevel explicitly and also broke the line into a few pieces
to avoid it being longer than 80 chars and clarified the text a bit.
Signed-off-by: Jesper Juhl <juhl-lkml@dif.dk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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