__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &__get_cpu_var(x). This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.
Other use cases are for storing and retrieving data from the current
processors percpu area. __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.
__get_cpu_var() is defined as :
#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))
__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.
this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.
This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset. Thereby address calculations are avoided and less registers
are used when code is generated.
At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.
The patch set includes passes over all arches as well. Once these operations
are used throughout then specialized macros can be defined in non -x86
arches as well in order to optimize per cpu access by f.e. using a global
register that may be set to the per cpu base.
Transformations done to __get_cpu_var()
1. Determine the address of the percpu instance of the current processor.
DEFINE_PER_CPU(int, y);
int *x = &__get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(&y);
2. Same as #1 but this time an array structure is involved.
DEFINE_PER_CPU(int, y[20]);
int *x = __get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(y);
3. Retrieve the content of the current processors instance of a per cpu
variable.
DEFINE_PER_CPU(int, y);
int x = __get_cpu_var(y)
Converts to
int x = __this_cpu_read(y);
4. Retrieve the content of a percpu struct
DEFINE_PER_CPU(struct mystruct, y);
struct mystruct x = __get_cpu_var(y);
Converts to
memcpy(&x, this_cpu_ptr(&y), sizeof(x));
5. Assignment to a per cpu variable
DEFINE_PER_CPU(int, y)
__get_cpu_var(y) = x;
Converts to
__this_cpu_write(y, x);
6. Increment/Decrement etc of a per cpu variable
DEFINE_PER_CPU(int, y);
__get_cpu_var(y)++
Converts to
__this_cpu_inc(y)
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: linux-ia64@vger.kernel.org
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
I'm not sure why, but the hlist for each entry iterators were conceived
list_for_each_entry(pos, head, member)
The hlist ones were greedy and wanted an extra parameter:
hlist_for_each_entry(tpos, pos, head, member)
Why did they need an extra pos parameter? I'm not quite sure. Not only
they don't really need it, it also prevents the iterator from looking
exactly like the list iterator, which is unfortunate.
Besides the semantic patch, there was some manual work required:
- Fix up the actual hlist iterators in linux/list.h
- Fix up the declaration of other iterators based on the hlist ones.
- A very small amount of places were using the 'node' parameter, this
was modified to use 'obj->member' instead.
- Coccinelle didn't handle the hlist_for_each_entry_safe iterator
properly, so those had to be fixed up manually.
The semantic patch which is mostly the work of Peter Senna Tschudin is here:
@@
iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host;
type T;
expression a,c,d,e;
identifier b;
statement S;
@@
-T b;
<+... when != b
(
hlist_for_each_entry(a,
- b,
c, d) S
|
hlist_for_each_entry_continue(a,
- b,
c) S
|
hlist_for_each_entry_from(a,
- b,
c) S
|
hlist_for_each_entry_rcu(a,
- b,
c, d) S
|
hlist_for_each_entry_rcu_bh(a,
- b,
c, d) S
|
hlist_for_each_entry_continue_rcu_bh(a,
- b,
c) S
|
for_each_busy_worker(a, c,
- b,
d) S
|
ax25_uid_for_each(a,
- b,
c) S
|
ax25_for_each(a,
- b,
c) S
|
inet_bind_bucket_for_each(a,
- b,
c) S
|
sctp_for_each_hentry(a,
- b,
c) S
|
sk_for_each(a,
- b,
c) S
|
sk_for_each_rcu(a,
- b,
c) S
|
sk_for_each_from
-(a, b)
+(a)
S
+ sk_for_each_from(a) S
|
sk_for_each_safe(a,
- b,
c, d) S
|
sk_for_each_bound(a,
- b,
c) S
|
hlist_for_each_entry_safe(a,
- b,
c, d, e) S
|
hlist_for_each_entry_continue_rcu(a,
- b,
c) S
|
nr_neigh_for_each(a,
- b,
c) S
|
nr_neigh_for_each_safe(a,
- b,
c, d) S
|
nr_node_for_each(a,
- b,
c) S
|
nr_node_for_each_safe(a,
- b,
c, d) S
|
- for_each_gfn_sp(a, c, d, b) S
+ for_each_gfn_sp(a, c, d) S
|
- for_each_gfn_indirect_valid_sp(a, c, d, b) S
+ for_each_gfn_indirect_valid_sp(a, c, d) S
|
for_each_host(a,
- b,
c) S
|
for_each_host_safe(a,
- b,
c, d) S
|
for_each_mesh_entry(a,
- b,
c, d) S
)
...+>
[akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c]
[akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c]
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix warnings]
[akpm@linux-foudnation.org: redo intrusive kvm changes]
Tested-by: Peter Senna Tschudin <peter.senna@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Disable kprobe booster when CONFIG_PREEMPT=y at this time,
because it can't ensure that all kernel threads preempted on
kprobe's boosted slot run out from the slot even using
freeze_processes().
The booster on preemptive kernel will be resumed if
synchronize_tasks() or something like that is introduced.
Signed-off-by: Masami 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: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20100202214904.4694.24330.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Check CONFIG_FREEZER instead of CONFIG_PM because kprobe booster
depends on freeze_processes() and thaw_processes() when CONFIG_PREEMPT=y.
This fixes a linkage error which occurs when CONFIG_PREEMPT=y, CONFIG_PM=y
and CONFIG_FREEZER=n.
Reported-by: Cheng Renquan <crquan@gmail.com>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Len Brown <len.brown@intel.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (24 commits)
trivial: chack -> check typo fix in main Makefile
trivial: Add a space (and a comma) to a printk in 8250 driver
trivial: Fix misspelling of "firmware" in docs for ncr53c8xx/sym53c8xx
trivial: Fix misspelling of "firmware" in powerpc Makefile
trivial: Fix misspelling of "firmware" in usb.c
trivial: Fix misspelling of "firmware" in qla1280.c
trivial: Fix misspelling of "firmware" in a100u2w.c
trivial: Fix misspelling of "firmware" in megaraid.c
trivial: Fix misspelling of "firmware" in ql4_mbx.c
trivial: Fix misspelling of "firmware" in acpi_memhotplug.c
trivial: Fix misspelling of "firmware" in ipw2100.c
trivial: Fix misspelling of "firmware" in atmel.c
trivial: Fix misspelled firmware in Kconfig
trivial: fix an -> a typos in documentation and comments
trivial: fix then -> than typos in comments and documentation
trivial: update Jesper Juhl CREDITS entry with new email
trivial: fix singal -> signal typo
trivial: Fix incorrect use of "loose" in event.c
trivial: printk: fix indentation of new_text_line declaration
trivial: rtc-stk17ta8: fix sparse warning
...
Add kprobe_insn_mutex for protecting kprobe_insn_pages hlist, and remove
kprobe_mutex from architecture dependent code.
This allows us to call arch_remove_kprobe() (and free_insn_slot) while
holding kprobe_mutex.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 <srinivasa@in.ibm.com>
Signed-off-by: Jim Keniston <jkenisto@us.ibm.com>
Acked-by: Ananth 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add kprobe-booster support on ia64.
Kprobe-booster improves the performance of kprobes by eliminating single-step,
where possible. Currently, kprobe-booster is implemented on x86 and x86-64.
This is an ia64 port.
On ia64, kprobe-booster executes a copied bundle directly, instead of single
stepping. Bundles which have B or X unit and which may cause an exception
(including break) are not executed directly. And also, to prevent hitting
break exceptions on the copied bundle, only the hindmost kprobe is executed
directly if several kprobes share a bundle and are placed in different slots.
Note: set_brl_inst() is used for preparing an instruction buffer(it does not
modify any active code), so it does not need any atomic operation.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: bibo,mao <bibo.mao@intel.com>
Cc: Rusty Lynch <rusty.lynch@intel.com>
Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
ia64 named their handler kprobes_fault_handler while all other
arches used kprobe_fault_handler. Change the function definition
and header declaration.
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This patch fixes the following compile error with a recent gcc:
CC kernel/kprobes.o
/home/bunk/linux/kernel-2.6/git/linux-2.6/kernel/kprobes.c:1066: error: __ksymtab_jprobe_return causes a section type conflict
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Fix the order of atomic operations to prevent overwriting prev_kprobe[0].
To pop values from stack, we must decrement stack index right AFTER
reading values.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Restore regs->ccr_iip before kreturn probe handler runs. In this way, if
probe handler does unwind, unwind can correctly get the stack trace.
Fixes: http://sourceware.org/bugzilla/show_bug.cgi?id=5051
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
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 <mhiramat@redhat.com>
Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I realise jprobes are a razor-blades-included type of interface, but that
doesn't mean we can't try and make them safer to use. This guy I know once
wrote code like this:
struct jprobe jp = { .kp.symbol_name = "foo", .entry = "jprobe_foo" };
And then his kernel exploded. Oops.
This patch adds an arch hook, arch_deref_entry_point() (I don't like it
either) which takes the void * in a struct jprobe, and gives back the text
address that it represents.
We can then use that in register_jprobe() to check that the entry point we're
passed is actually in the kernel text, rather than just some random value.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Get rid of the notifier list and call the kprobes code directly
if compiled in. This mirrors the changes that recently went
into powerpc, s390 and sparc64.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Tony Luck <tony.luck@intel.com>
In case of reentrance i.e when a probe handler calls a functions which
inturn has a probe, we save a previous kprobe information and just single
step the reentrant probe without calling the actual probe handler. During
this reentracy period, if an interrupt occurs and if probe happens to
trigger in the inturrupt path, then we were corrupting the previous kprobe(
as we were overriding the previous kprobe info) info their by crashing the
system. This patch fixes this issues by having a an array of previous
kprobe info struct(with the array size of 2).
This similar technique is not needed on i386 and x86_64 because by default
interrupts are turn off in the break/int3 exception handler.
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This patch provides a debugfs knob to turn kprobes on/off
o A new file /debug/kprobes/enabled indicates if kprobes is enabled or
not (default enabled)
o Echoing 0 to this file will disarm all installed probes
o Any new probe registration when disabled will register the probe but
not arm it. A message will be printed out in such a case.
o When a value 1 is echoed to the file, all probes (including ones
registered in the intervening period) will be enabled
o Unregistration will happen irrespective of whether probes are globally
enabled or not.
o Update Documentation/kprobes.txt to reflect these changes. While there
also update the doc to make it current.
We are also looking at providing sysrq key support to tie to the disabling
feature provided by this patch.
[akpm@linux-foundation.org: Use bool like a bool!]
[akpm@linux-foundation.org: add printk facility levels]
[cornelia.huck@de.ibm.com: Add the missing arch_trampoline_kprobe() for s390]
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Srinivasa DS <srinivasa@in.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- consolidate duplicate code in all arch_prepare_kretprobe instances
into common code
- replace various odd helpers that use hlist_for_each_entry to get
the first elemenet of a list with either a hlist_for_each_entry_save
or an opencoded access to the first element in the caller
- inline add_rp_inst into it's only remaining caller
- use kretprobe_inst_table_head instead of opencoding it
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In certain cases like when the real return address can't be found or when
the number of tracked calls to a kretprobed function is less than the
number of returns, we may not be able to find the correct return address
after processing a kretprobe. Currently we just do a BUG_ON, but no
information is provided about the actual failing kretprobe.
Print out details of the kretprobe before calling BUG().
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch moves the die notifier handling to common code. Previous
various architectures had exactly the same code for it. Note that the new
code is compiled unconditionally, this should be understood as an appel to
the other architecture maintainer to implement support for it aswell (aka
sprinkling a notify_die or two in the proper place)
arm had a notifiy_die that did something totally different, I renamed it to
arm_notify_die as part of the patch and made it static to the file it's
declared and used at. avr32 used to pass slightly less information through
this interface and I brought it into line with the other architectures.
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: fix vmalloc_sync_all bustage]
[bryan.wu@analog.com: fix vmalloc_sync_all in nommu]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: <linux-arch@vger.kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On IA64 there exists some special instructions which
always need to be executed regradless of qp bits, such
as com.crel.unc, tbit.trel.unc etc.
This patch clears qp bits when inserting kprobe trap code
and disables probepoint on slot 1 for these special
instructions.
Signed-off-by: bibo,mao <bibo.mao@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Because slot 1 of one instr bundle crosses border of two consecutive
8-bytes, kprobe on slot 1 is disabled. This patch enables kprobe on
slot1, it only replaces higher 8-bytes of the instruction bundle and
changes the exception code to ignore the low 12 bits of the break
number (which is across the border in the lower 8-bytes of the bundle).
For those instructions which must execute regardless qp bits,
kprobe on slot 1 is still disabled.
Signed-off-by: bibo,mao <bibo.mao@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
* 'release' of master.kernel.org:/pub/scm/linux/kernel/git/aegl/linux-2.6:
[IA64] replace kmalloc+memset with kzalloc
[IA64] resolve name clash by renaming is_available_memory()
[IA64] Need export for csum_ipv6_magic
[IA64] Fix DISCONTIGMEM without VIRTUAL_MEM_MAP
[PATCH] Add support for type argument in PAL_GET_PSTATE
[IA64] tidy up return value of ip_fast_csum
[IA64] implement csum_ipv6_magic for ia64.
[IA64] More Itanium PAL spec updates
[IA64] Update processor_info features
[IA64] Add se bit to Processor State Parameter structure
[IA64] Add dp bit to cache and bus check structs
[IA64] SN: Correctly update smp_affinty mask
[IA64] sparse cleanups
[IA64] IA64 Kexec/kdump
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: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
kprobe_flush_task() possibly calls kfree function during holding
kretprobe_lock spinlock, if kfree function is probed by kretprobe that will
incur spinlock deadlock. This patch moves kfree function out scope of
kretprobe_lock.
Signed-off-by: bibo, mao <bibo.mao@intel.com>
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Whitespace is used to indent, this patch cleans up these sentences by
kernel coding style.
Signed-off-by: bibo, mao <bibo.mao@intel.com>
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
If the user-specified kprobe handler causes the page fault when accessing
user space address, fixup this fault since do_page_fault() should not
continue as the kprobe handler are run with preemption disabled.
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
On IA64 instruction opcode must be 16 bytes alignment, in kprobe structure
there is one element to save original instruction, currently saved opcode
is not statically allocated in kprobe structure, that can not assure
16 bytes alignment. This patch dynamically allocated kprobe instruction
opcode to assure 16 bytes alignment.
Signed-off-by: bibo mao <bibo.mao@intel.com>
Acked-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Kprobe inserts breakpoint instruction in probepoint and then jumps to
instruction slot when breakpoint is hit, the instruction slot icache must
be consistent with dcache. Here is the patch which invalidates instruction
slot icache area.
Without this patch, in some machines there will be fault when executing
instruction slot where icache content is inconsistent with dcache.
Signed-off-by: bibo,mao <bibo.mao@intel.com>
Acked-by: "Luck, Tony" <tony.luck@intel.com>
Acked-by: Keshavamurthy Anil S <anil.s.keshavamurthy@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Andrew Morton pointed out that compiler might not inline the functions
marked for inline in kprobes. There-by allowing the insertion of probes
on these kprobes routines, which might cause recursion.
This patch removes all such inline and adds them to kprobes section
there by disallowing probes on all such routines. Some of the routines
can even still be inlined, since these routines gets executed after the
kprobes had done necessay setup for reentrancy.
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Provide proper kprobes fault handling, if a user-specified pre/post handlers
tries to access user address space, through copy_from_user(), get_user() etc.
The user-specified fault handler gets called only if the fault occurs while
executing user-specified handlers. In such a case user-specified handler is
allowed to fix it first, later if the user-specifed fault handler does not fix
it, we try to fix it by calling fix_exception().
The user-specified handler will not be called if the fault happens when single
stepping the original instruction, instead we reset the current probe and
allow the system page fault handler to fix it up.
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Acked-by: Anil S Keshavamurthy<anil.s.keshavamurthy@intel.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Currently kprobe handler traps only happen in kernel space, so function
kprobe_exceptions_notify should skip traps which happen in user space.
This patch modifies this, and it is based on 2.6.16-rc4.
Signed-off-by: bibo mao <bibo.mao@intel.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com>
Cc: <hiramatu@sdl.hitachi.co.jp>
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>
When jprobe is hit, the function parameters of the original function
should be saved before jprobe handler is executed, and restored it after
jprobe handler is executed, because jprobe handler might change the
register values due to tail call optimization by the gcc.
Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
There is a window where a probe gets removed right after the probe is hit
on some different cpu. In this case probe handlers can't find a matching
probe instance related to break address. In this case we need to read the
original instruction at break address to see if that is not a break/int3
instruction and recover safely.
Previous code had a bug where we were not checking for the above race in
case of reentrant probes and the below patch fixes this race.
Tested on IA64, Powerpc, x86_64.
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>
Currently arch_remove_kprobes() is only implemented/required for x86_64 and
powerpc. All other architecture like IA64, i386 and sparc64 implementes a
dummy function which is being called from arch independent kprobes.c file.
This patch removes the dummy functions and replaces it with
#define arch_remove_kprobe(p, s) do { } while(0)
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>
When multiple probes are registered at the same address and if due to some
recursion (probe getting triggered within a probe handler), we skip calling
pre_handlers and just increment nmissed field.
The below patch make sure it walks the list for multiple probes case.
Without the below patch we get incorrect results of nmissed count for
multiple probe case.
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>
break.b always sets cr.iim to 0 and the current code tries to
get the break_num by decoding instruction. However, their
seems to be a race condition while reading the regs->cr_iip,
as on other cpu the break.b at regs->cr_iip might have been
replaced with the original instruction as a result of
unregister_kprobe() and hence decoding instruction to
obtain break_num will result in wrong value in this case.
Also includes changes to kprobes.c which now has to handle
break number zero.
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
notify_die() added for MCA_{MONARCH,SLAVE,RENDEZVOUS}_{ENTER,PROCESS,LEAVE} and
INIT_{MONARCH,SLAVE}_{ENTER,PROCESS,LEAVE}. We need multiple
notification points for these events because they can take many seconds
to run which has nasty effects on the behaviour of the rest of the
system.
DIE_SS replaced by a generic DIE_FAULT which checks the vector number,
to allow interception of faults other than SS.
DIE_MACHINE_{HALT,RESTART} added to allow last minute close down
processing, especially when the halt/restart routines are called from
error handlers.
DIE_OOPS added.
The check for kprobe's break numbers has been moved from traps.c to
kprobes.c, allowing DIE_BREAK to be used for any additional break
numbers, i.e. it is no longer kprobes specific.
Hooks for kernel debuggers and kernel dumpers added, ENTER and LEAVE.
Both of these disable the system for long periods which impact on
watchdogs and heartbeat systems in general. More patches to come that
use these events to reset watchdogs and heartbeats.
unregister_die_notifier() added and both routines exported. Requested
by Dean Nelson.
Lock removed from {un,}register_die_notifier. notifier_chain_register()
already takes a lock. Also the generic notifier chain locking is being
reworked to distinguish between callbacks that can block and those that
cannot, the lock in {un,}register_die_notifier would interfere with
that change. http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
Leading white space removed from arch/ia64/kernel/kprobes.c.
Typo in mca.c in original version of this patch found & fixed by Dean
Nelson.
Signed-off-by: Keith Owens <kaos@sgi.com>
Acked-by: Dean Nelson <dcn@sgi.com>
Acked-by: Anil Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Reorganize the preempt_disable/enable calls to eliminate the extra preempt
depth. Changes based on Paul McKenney's review suggestions for the kprobes
RCU changeset.
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.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>
Changes to the arch kprobes infrastructure to take advantage of the locking
changes introduced by usage of RCU for synchronization. All handlers are now
run without any locks held, so they have to be re-entrant or provide their own
synchronization.
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.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>
IA64 changes to track kprobe execution on a per-cpu basis. We now track the
kprobe state machine independently on each cpu using an arch specific kprobe
control block.
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.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>
The following set of patches are aimed at improving kprobes scalability. We
currently serialize kprobe registration, unregistration and handler execution
using a single spinlock - kprobe_lock.
With these changes, kprobe handlers can run without any locks held. It also
allows for simultaneous kprobe handler executions on different processors as
we now track kprobe execution on a per processor basis. It is now necessary
that the handlers be re-entrant since handlers can run concurrently on
multiple processors.
All changes have been tested on i386, ia64, ppc64 and x86_64, while sparc64
has been compile tested only.
The patches can be viewed as 3 logical chunks:
patch 1: Reorder preempt_(dis/en)able calls
patches 2-7: Introduce per_cpu data areas to track kprobe execution
patches 8-9: Use RCU to synchronize kprobe (un)registration and handler
execution.
Thanks to Maneesh Soni, James Keniston and Anil Keshavamurthy for their
review and suggestions. Thanks again to Anil, Hien Nguyen and Kevin Stafford
for testing the patches.
This patch:
Reorder preempt_disable/enable() calls in arch kprobes files in preparation to
introduce locking changes. No functional changes introduced by this patch.
Signed-off-by: Ananth N Mavinakayahanalli <ananth@in.ibm.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>
This patch fixes a race condition where in system used to hang or sometime
crash within minutes when kprobes are inserted on ISR routine and a task
routine.
The fix has been stress tested on i386, ia64, pp64 and on x86_64. To
reproduce the problem insert kprobes on schedule() and do_IRQ() functions
and you should see hang or system crash.
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.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>
This patch addresses a potential race condition for a case where Kprobe has
been removed right after another CPU has taken a break hit.
The way this is addressed here is when the CPU that has taken a break hit
does not find its corresponding kprobe, then we check to see if the
original instruction got replaced with other than break. If it got
replaced with other than break instruction, then we continue to execute
from the replaced instruction, else if we find that it is still a break,
then we let the kernel handle this, as this might be the break instruction
inserted by other than kprobe(may be kernel debugger).
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>
