Commit Graph

68 Commits

Author SHA1 Message Date
Rabin Vincent 78345d2edc x86: Call stop_machine_text_poke() on all CPUs
It appears that stop_machine_text_poke() wants to be called on all CPUs,
like it's done from text_poke_smp().  Fix text_poke_smp_batch() to do
this.

Signed-off-by: Rabin Vincent <rabin@rab.in>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Jason Baron <jbaron@redhat.com>
Link: http://lkml.kernel.org/r/1319702072-32676-1-git-send-email-rabin@rab.in
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-11-14 13:05:15 +01:00
Andy Lutomirski 98d0ac38ca x86-64: Move vread_tsc and vread_hpet into the vDSO
The vsyscall page now consists entirely of trap instructions.

Cc: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/637648f303f2ef93af93bae25186e9a1bea093f5.1310639973.git.luto@mit.edu
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2011-07-14 17:57:05 -07:00
Andy Lutomirski 59e97e4d6f x86: Make alternative instruction pointers relative
This save a few bytes on x86-64 and means that future patches can
apply alternatives to unrelocated code.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/ff64a6b9a1a3860ca4a7b8b6dc7b4754f9491cd7.1310563276.git.luto@mit.edu
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2011-07-13 11:22:56 -07:00
Linus Torvalds 0162818804 Merge branch 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, cpu: Fix detection of Celeron Covington stepping A1 and B0
  Documentation, ABI: Update L3 cache index disable text
  x86, AMD, cacheinfo: Fix L3 cache index disable checks
  x86, AMD, cacheinfo: Fix fallout caused by max3 conversion
  x86, cpu: Change NOP selection for certain Intel CPUs
  x86, cpu: Clean up and unify the NOP selection infrastructure
  x86, percpu: Use ASM_NOP4 instead of hardcoding P6_NOP4
  x86, cpu: Move AMD Elan Kconfig under "Processor family"

Fix up trivial conflicts in alternative handling (commit dc326fca2b
"x86, cpu: Clean up and unify the NOP selection infrastructure" removed
some hacky 5-byte instruction stuff, while commit d430d3d7e6 "jump
label: Introduce static_branch() interface" renamed HAVE_JUMP_LABEL to
CONFIG_JUMP_LABEL in the code that went away)
2011-05-19 17:55:12 -07:00
Ingo Molnar 01ed58abec Merge branch 'x86/mem' into perf/core
Merge reason: memcpy_64.S changes an assumption perf bench has, so merge this
              here so we can fix it.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-18 20:59:30 +02:00
Fenghua Yu 5097313363 x86, alternative, doc: Add comment for applying alternatives order
Some string operation functions may be patched twice, e.g. on enhanced REP MOVSB
/STOSB processors, memcpy is patched first by fast string alternative function,
then it is patched by enhanced REP MOVSB/STOSB alternative function.

Add comment for applying alternatives order to warn people who may change the
applying alternatives order for any reason.

[ Documentation-only patch ]

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1305671358-14478-4-git-send-email-fenghua.yu@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2011-05-17 15:40:25 -07:00
H. Peter Anvin d8d9766c8c x86, cpu: Change NOP selection for certain Intel CPUs
Due to a decoder implementation quirk, some specific Intel CPUs
actually perform better with the "k8_nops" than with the
SDM-recommended NOPs.  For runtime-selected NOPs, if we detect those
specific CPUs then use the k8_nops instead of the ones we would
normally use.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>
Link: http://lkml.kernel.org/r/1303166160-10315-4-git-send-email-hpa@linux.intel.com
2011-04-18 16:40:32 -07:00
H. Peter Anvin dc326fca2b x86, cpu: Clean up and unify the NOP selection infrastructure
Clean up and unify the NOP selection infrastructure:

- Make the atomic 5-byte NOP a part of the selection system.
- Pick NOPs once during early boot and then be done with it.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>
Link: http://lkml.kernel.org/r/1303166160-10315-3-git-send-email-hpa@linux.intel.com
2011-04-18 16:40:21 -07:00
Jason Baron d430d3d7e6 jump label: Introduce static_branch() interface
Introduce:

static __always_inline bool static_branch(struct jump_label_key *key);

instead of the old JUMP_LABEL(key, label) macro.

In this way, jump labels become really easy to use:

Define:

        struct jump_label_key jump_key;

Can be used as:

        if (static_branch(&jump_key))
                do unlikely code

enable/disale via:

        jump_label_inc(&jump_key);
        jump_label_dec(&jump_key);

that's it!

For the jump labels disabled case, the static_branch() becomes an
atomic_read(), and jump_label_inc()/dec() are simply atomic_inc(),
atomic_dec() operations. We show testing results for this change below.

Thanks to H. Peter Anvin for suggesting the 'static_branch()' construct.

Since we now require a 'struct jump_label_key *key', we can store a pointer into
the jump table addresses. In this way, we can enable/disable jump labels, in
basically constant time. This change allows us to completely remove the previous
hashtable scheme. Thanks to Peter Zijlstra for this re-write.

Testing:

I ran a series of 'tbench 20' runs 5 times (with reboots) for 3
configurations, where tracepoints were disabled.

jump label configured in
avg: 815.6

jump label *not* configured in (using atomic reads)
avg: 800.1

jump label *not* configured in (regular reads)
avg: 803.4

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20110316212947.GA8792@redhat.com>
Signed-off-by: Jason Baron <jbaron@redhat.com>
Suggested-by: H. Peter Anvin <hpa@linux.intel.com>
Tested-by: David Daney <ddaney@caviumnetworks.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-04-04 12:48:08 -04:00
Lucas De Marchi 0d2eb44f63 x86: Fix common misspellings
They were generated by 'codespell' and then manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: trivial@kernel.org
LKML-Reference: <1300389856-1099-3-git-send-email-lucas.demarchi@profusion.mobi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-03-18 10:39:30 +01:00
Mathieu Desnoyers 0e00f7aed6 x86: stop_machine_text_poke() should issue sync_core()
Intel Archiecture Software Developer's Manual section 7.1.3 specifies that a
core serializing instruction such as "cpuid" should be executed on _each_ core
before the new instruction is made visible.

Failure to do so can lead to unspecified behavior (Intel XMC erratas include
General Protection Fault in the list), so we should avoid this at all cost.

This problem can affect modified code executed by interrupt handlers after
interrupt are re-enabled at the end of stop_machine, because no core serializing
instruction is executed between the code modification and the moment interrupts
are reenabled.

Because stop_machine_text_poke performs the text modification from the first CPU
decrementing stop_machine_first, modified code executed in thread context is
also affected by this problem. To explain why, we have to split the CPUs in two
categories: the CPU that initiates the text modification (calls text_poke_smp)
and all the others. The scheduler, executed on all other CPUs after
stop_machine, issues an "iret" core serializing instruction, and therefore
handles core serialization for all these CPUs. However, the text modification
initiator can continue its execution on the same thread and access the modified
text without any scheduler call. Given that the CPU that initiates the code
modification is not guaranteed to be the one actually performing the code
modification, it falls into the XMC errata.

Q: Isn't this executed from an IPI handler, which will return with IRET (a
   serializing instruction) anyway?
A: No, now stop_machine uses per-cpu workqueue, so that handler will be
   executed from worker threads. There is no iret anymore.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
LKML-Reference: <20110303160137.GB1590@Krystal>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: <stable@kernel.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2011-03-15 08:36:37 -07:00
Peter Zijlstra d91309f69b x86: Fix text_poke_smp_batch() deadlock
Fix this deadlock - we are already holding the mutex:

=======================================================
[ INFO: possible circular locking dependency detected ] 2.6.38-rc4-test+ #1
-------------------------------------------------------
bash/1850 is trying to acquire lock:
 (text_mutex){+.+.+.}, at: [<ffffffff8100a9c1>] return_to_handler+0x0/0x2f

but task is already holding lock:
 (smp_alt){+.+...}, at: [<ffffffff8100a9c1>] return_to_handler+0x0/0x2f

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (smp_alt){+.+...}:
       [<ffffffff81082d02>] lock_acquire+0xcd/0xf8
       [<ffffffff8192e119>] __mutex_lock_common+0x4c/0x339
       [<ffffffff8192e4ca>] mutex_lock_nested+0x3e/0x43
       [<ffffffff8101050f>] alternatives_smp_switch+0x77/0x1d8
       [<ffffffff81926a6f>] do_boot_cpu+0xd7/0x762
       [<ffffffff819277dd>] native_cpu_up+0xe6/0x16a
       [<ffffffff81928e28>] _cpu_up+0x9d/0xee
       [<ffffffff81928f4c>] cpu_up+0xd3/0xe7
       [<ffffffff82268d4b>] kernel_init+0xe8/0x20a
       [<ffffffff8100ba24>] kernel_thread_helper+0x4/0x10

-> #1 (cpu_hotplug.lock){+.+.+.}:
       [<ffffffff81082d02>] lock_acquire+0xcd/0xf8
       [<ffffffff8192e119>] __mutex_lock_common+0x4c/0x339
       [<ffffffff8192e4ca>] mutex_lock_nested+0x3e/0x43
       [<ffffffff810568cc>] get_online_cpus+0x41/0x55
       [<ffffffff810a1348>] stop_machine+0x1e/0x3e
       [<ffffffff819314c1>] text_poke_smp_batch+0x3a/0x3c
       [<ffffffff81932b6c>] arch_optimize_kprobes+0x10d/0x11c
       [<ffffffff81933a51>] kprobe_optimizer+0x152/0x222
       [<ffffffff8106bb71>] process_one_work+0x1d3/0x335
       [<ffffffff8106cfae>] worker_thread+0x104/0x1a4
       [<ffffffff810707c4>] kthread+0x9d/0xa5
       [<ffffffff8100ba24>] kernel_thread_helper+0x4/0x10

-> #0 (text_mutex){+.+.+.}:

other info that might help us debug this:

6 locks held by bash/1850:
 #0:  (&buffer->mutex){+.+.+.}, at: [<ffffffff8100a9c1>] return_to_handler+0x0/0x2f
 #1:  (s_active#75){.+.+.+}, at: [<ffffffff8100a9c1>] return_to_handler+0x0/0x2f
 #2:  (x86_cpu_hotplug_driver_mutex){+.+.+.}, at: [<ffffffff8100a9c1>] return_to_handler+0x0/0x2f
 #3:  (cpu_add_remove_lock){+.+.+.}, at: [<ffffffff8100a9c1>] return_to_handler+0x0/0x2f
 #4:  (cpu_hotplug.lock){+.+.+.}, at: [<ffffffff8100a9c1>] return_to_handler+0x0/0x2f
 #5:  (smp_alt){+.+...}, at: [<ffffffff8100a9c1>] return_to_handler+0x0/0x2f

stack backtrace:
Pid: 1850, comm: bash Not tainted 2.6.38-rc4-test+ #1
Call Trace:

 [<ffffffff81080eb2>] print_circular_bug+0xa8/0xb7
 [<ffffffff8192e4ca>] mutex_lock_nested+0x3e/0x43
 [<ffffffff81010302>] alternatives_smp_unlock+0x3d/0x93
 [<ffffffff81010630>] alternatives_smp_switch+0x198/0x1d8
 [<ffffffff8102568a>] native_cpu_die+0x65/0x95
 [<ffffffff818cc4ec>] _cpu_down+0x13e/0x202
 [<ffffffff8117a619>] sysfs_write_file+0x108/0x144
 [<ffffffff8111f5a2>] vfs_write+0xac/0xff
 [<ffffffff8111f7a9>] sys_write+0x4a/0x6e

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Tested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: mathieu.desnoyers@efficios.com
Cc: rusty@rustcorp.com.au
Cc: ananth@in.ibm.com
Cc: masami.hiramatsu.pt@hitachi.com
Cc: fweisbec@gmail.com
Cc: jbeulich@novell.com
Cc: jbaron@redhat.com
Cc: mhiramat@redhat.com
LKML-Reference: <1297458466.5226.93.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-02-12 02:34:34 +01:00
Linus Torvalds 47935a731b Merge branches 'x86-alternatives-for-linus', 'x86-fpu-for-linus', 'x86-hwmon-for-linus', 'x86-paravirt-for-linus', 'core-locking-for-linus' and 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-alternatives-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, suspend: Avoid unnecessary smp alternatives switch during suspend/resume

* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86-64, asm: Use fxsaveq/fxrestorq in more places

* 'x86-hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, hwmon: Add core threshold notification to therm_throt.c

* 'x86-paravirt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, paravirt: Use native_halt on a halt, not native_safe_halt

* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  locking, lockdep: Convert sprintf_symbol to %pS

* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  irq: Better struct irqaction layout
2011-01-06 11:11:50 -08:00
Suresh Siddha 3fb82d56ad x86, suspend: Avoid unnecessary smp alternatives switch during suspend/resume
During suspend, we disable all the non boot cpus. And during resume we bring
them all back again. So no need to do alternatives_smp_switch() in between.

On my core 2 based laptop, this speeds up the suspend path by 15msec and the
resume path by 5 msec (suspend/resume speed up differences can be attributed
to the different P-states that the cpu is in during suspend/resume).

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <1290557500.4946.8.camel@sbsiddha-MOBL3.sc.intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2010-12-13 16:23:56 -08:00
Masami Hiramatsu 7deb18dcf0 x86: Introduce text_poke_smp_batch() for batch-code modifying
Introduce text_poke_smp_batch(). This function modifies several
text areas with one stop_machine() on SMP. Because calling
stop_machine() is heavy task, it is better to aggregate
text_poke requests.

( Note: I've talked with Rusty about this interface, and
  he would not like to expand stop_machine() interface, since
  it is not for generic use. )

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: 2nddept-manager@sdl.hitachi.co.jp
LKML-Reference: <20101203095422.2961.51217.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-12-06 17:59:31 +01:00
Linus Torvalds f02a38d86a Merge branches 'perf-fixes-for-linus' and 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  jump label: Add work around to i386 gcc asm goto bug
  x86, ftrace: Use safe noops, drop trap test
  jump_label: Fix unaligned traps on sparc.
  jump label: Make arch_jump_label_text_poke_early() optional
  jump label: Fix error with preempt disable holding mutex
  oprofile: Remove deprecated use of flush_scheduled_work()
  oprofile: Fix the hang while taking the cpu offline
  jump label: Fix deadlock b/w jump_label_mutex vs. text_mutex
  jump label: Fix module __init section race

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: Check irq_remapped instead of remapping_enabled in destroy_irq()
2010-10-30 11:43:26 -07:00
Jason Baron 404ba5d7bb x86, alternative: Call stop_machine_text_poke() on all cpus
Currently, text_poke_smp() passes a NULL as the third argument to
__stop_machine(), which will only run stop_machine_text_poke()
on 1 cpu. Change NULL -> cpu_online_mask, as stop_machine_text_poke()
is intended to be run on all cpus.

I actually didn't notice any problems with stop_machine_text_poke()
only being called on 1 cpu, but found this via code inspection.

Signed-off-by: Jason Baron <jbaron@redhat.com>
LKML-Reference: <20101028152026.GB2875@redhat.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2010-10-29 16:42:58 -07:00
H. Peter Anvin 2d1d7126bb x86, ftrace: Use safe noops, drop trap test
Always use a safe 5-byte noop sequence.  Drop the trap test, since it
is known to return false negatives on some virtualization platforms on
32 bits.  The resulting code is both simpler and safer.

Cc: Daniel Drake <dsd@laptop.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2010-10-29 13:07:59 -04:00
Masami Hiramatsu 3caa37519c x86: Use __stop_machine() in text_poke_smp()
Use __stop_machine() in text_poke_smp() because the caller
must get online_cpus before calling text_poke_smp(), but
stop_machine() do it again. We don't need it.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: 2nddept-manager@sdl.hitachi.co.jp
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
LKML-Reference: <20101014031036.4100.83989.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-10-14 08:55:28 +02:00
Jason Baron bf5438fca2 jump label: Base patch for jump label
base patch to implement 'jump labeling'. Based on a new 'asm goto' inline
assembly gcc mechanism, we can now branch to labels from an 'asm goto'
statment. This allows us to create a 'no-op' fastpath, which can subsequently
be patched with a jump to the slowpath code. This is useful for code which
might be rarely used, but which we'd like to be able to call, if needed.
Tracepoints are the current usecase that these are being implemented for.

Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jason Baron <jbaron@redhat.com>
LKML-Reference: <ee8b3595967989fdaf84e698dc7447d315ce972a.1284733808.git.jbaron@redhat.com>

[ cleaned up some formating ]

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2010-09-22 16:29:41 -04:00
Jason Baron fa6f2cc770 jump label: Make text_poke_early() globally visible
Make text_poke_early available outside of alternative.c. The jump label
patchset wants to make use of it in order to set up the optimal no-op
sequences at run-time.

Signed-off-by: Jason Baron <jbaron@redhat.com>
LKML-Reference: <04cfddf2ba77bcabfc3e524f1849d871d6a1cf9d.1284733808.git.jbaron@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2010-09-20 18:19:51 -04:00
Jason Baron f49aa44856 jump label: Make dynamic no-op selection available outside of ftrace
Move Steve's code for finding the best 5-byte no-op from ftrace.c to
alternative.c. The idea is that other consumers (in this case jump label)
want to make use of that code.

Signed-off-by: Jason Baron <jbaron@redhat.com>
LKML-Reference: <96259ae74172dcac99c0020c249743c523a92e18.1284733808.git.jbaron@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2010-09-20 18:19:39 -04:00
H. Peter Anvin 3b770a2128 x86, alternatives: BUG on encountering an invalid CPU feature number
Make the alternatives-patching code BUG on encountering an invalid CPU
feature number.  Should have done this a long time ago.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Yinghai Lu <yinhai@kernel.org>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <tip-df378ccfc4dd04e263426ad805516915874774aa@git.kernel.org>
2010-07-13 14:57:50 -07:00
H. Peter Anvin d9c5841e22 Merge branch 'x86/asm' into x86/atomic
Merge reason:
	Conflict between LOCK_PREFIX_HERE and relative alternatives
	pointers

Resolved Conflicts:
	arch/x86/include/asm/alternative.h
	arch/x86/kernel/alternative.c

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2010-04-29 16:53:17 -07:00
Jan Beulich 5967ed87ad x86-64: Reduce SMP locks table size
Reduce the SMP locks table size by using relative pointers instead of
absolute ones, thus cutting the table size by half.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <4BCF30FE020000780003B3B6@vpn.id2.novell.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2010-04-28 17:15:47 -07:00
Tejun Heo 5a0e3ad6af include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-30 22:02:32 +09:00
Linus Torvalds 660f6a360b Merge branch 'perf-probes-for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'perf-probes-for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: Issue at least one memory barrier in stop_machine_text_poke()
  perf probe: Correct probe syntax on command line help
  perf probe: Add lazy line matching support
  perf probe: Show more lines after last line
  perf probe: Check function address range strictly in line finder
  perf probe: Use libdw callback routines
  perf probe: Use elfutils-libdw for analyzing debuginfo
  perf probe: Rename probe finder functions
  perf probe: Fix bugs in line range finder
  perf probe: Update perf probe document
  perf probe: Do not show --line option without dwarf support
  kprobes: Add documents of jump optimization
  kprobes/x86: Support kprobes jump optimization on x86
  x86: Add text_poke_smp for SMP cross modifying code
  kprobes/x86: Cleanup save/restore registers
  kprobes/x86: Boost probes when reentering
  kprobes: Jump optimization sysctl interface
  kprobes: Introduce kprobes jump optimization
  kprobes: Introduce generic insn_slot framework
  kprobes/x86: Cleanup RELATIVEJUMP_INSTRUCTION to RELATIVEJUMP_OPCODE
2010-03-05 10:50:22 -08:00
Masami Hiramatsu e5a1101664 x86: Issue at least one memory barrier in stop_machine_text_poke()
Fix stop_machine_text_poke() to issue smp_mb() before exiting
waiting loop, and use cpu_relax() for waiting.

Changes in v2:
 - Don't use ACCESS_ONCE().

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Jason Baron <jbaron@redhat.com>
LKML-Reference: <20100304033850.3819.74590.stgit@localhost6.localdomain6>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-03-04 11:39:21 +01:00
Linus Torvalds a7f16d10b5 Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: Mark atomic irq ops raw for 32bit legacy
  x86: Merge show_regs()
  x86: Macroise x86 cache descriptors
  x86-32: clean up rwsem inline asm statements
  x86: Merge asm/atomic_{32,64}.h
  x86: Sync asm/atomic_32.h and asm/atomic_64.h
  x86: Split atomic64_t functions into seperate headers
  x86-64: Modify memcpy()/memset() alternatives mechanism
  x86-64: Modify copy_user_generic() alternatives mechanism
  x86: Lift restriction on the location of FIX_BTMAP_*
  x86, core: Optimize hweight32()
2010-02-28 10:35:09 -08:00
Luca Barbieri b3ac891b67 x86: Add support for lock prefix in alternatives
The current lock prefix UP/SMP alternative code doesn't allow
LOCK_PREFIX to be used in alternatives code.

This patch solves the problem by adding a new LOCK_PREFIX_ALTERNATIVE_PATCH
macro that only records the lock prefix location but does not emit
the prefix.

The user of this macro can then start any alternative sequence with
"lock" and have it UP/SMP patched.

To make this work, the UP/SMP alternative code is changed to do the
lock/DS prefix switching only if the byte actually contains a lock or
DS prefix.

Thus, if an alternative without the "lock" is selected, it will now do
nothing instead of clobbering the code.

Changes in v2:
- Naming change
- Change label to not conflict with alternatives

Signed-off-by: Luca Barbieri <luca@luca-barbieri.com>
LKML-Reference: <1267005265-27958-2-git-send-email-luca@luca-barbieri.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2010-02-25 20:46:23 -08:00
Masami Hiramatsu 3d55cc8a05 x86: Add text_poke_smp for SMP cross modifying code
Add generic text_poke_smp for SMP which uses stop_machine()
to synchronize modifying code.
This stop_machine() method is officially described at "7.1.3
Handling Self- and Cross-Modifying Code" on the intel's
software developer's manual 3A.

Since stop_machine() can't protect code against NMI/MCE, this
function can not modify those handlers. And also, this function
is basically for modifying multibyte-single-instruction. For
modifying multibyte-multi-instructions, we need another special
trap & detour code.

This code originaly comes from immediate values with
stop_machine() version. Thanks Jason and Mathieu!

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
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: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
LKML-Reference: <20100225133438.6725.80273.stgit@localhost6.localdomain6>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-02-25 17:49:26 +01:00
Masami Hiramatsu 076dc4a65a x86/alternatives: Fix build warning
Fixes these warnings:

 arch/x86/kernel/alternative.c: In function 'alternatives_text_reserved':
 arch/x86/kernel/alternative.c:402: warning: comparison of distinct pointer types lacks a cast
 arch/x86/kernel/alternative.c:402: warning: comparison of distinct pointer types lacks a cast
 arch/x86/kernel/alternative.c:405: warning: comparison of distinct pointer types lacks a cast
 arch/x86/kernel/alternative.c:405: warning: comparison of distinct pointer types lacks a cast

Caused by:

  2cfa197: ftrace/alternatives: Introducing *_text_reserved functions

Changes in v2:
  - Use local variables to compare, instead of type casts.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
LKML-Reference: <20100205171647.15750.37221.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-02-07 18:08:24 +01:00
Masami Hiramatsu 2cfa19780d ftrace/alternatives: Introducing *_text_reserved functions
Introducing *_text_reserved functions for checking the text
address range is partially reserved or not. This patch provides
checking routines for x86 smp alternatives and dynamic ftrace.
Since both functions modify fixed pieces of kernel text, they
should reserve and protect those from other dynamic text
modifier, like kprobes.

This will also be extended when introducing other subsystems
which modify fixed pieces of kernel text. Dynamic text modifiers
should avoid those.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: przemyslaw@pawelczyk.it
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Jason Baron <jbaron@redhat.com>
LKML-Reference: <20100202214911.4694.16587.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-02-04 09:36:19 +01:00
Jan Beulich 1b1d925818 x86-64: Modify copy_user_generic() alternatives mechanism
In order to avoid unnecessary chains of branches, rather than
implementing copy_user_generic() as a function consisting of
just a single (possibly patched) branch, instead properly deal
with patching call instructions in the alternative instructions
framework, and move the patching into the callers.

As a follow-on, one could also introduce something like
__EXPORT_SYMBOL_ALT() to avoid patching call sites in modules.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <4B2BB8180200007800026AE7@vpn.id2.novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-12-30 11:57:31 +01:00
Linus Torvalds c7208de304 Merge branch 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (22 commits)
  x86: Fix code patching for paravirt-alternatives on 486
  x86, msr: change msr-reg.o to obj-y, and export its symbols
  x86: Use hard_smp_processor_id() to get apic id for AMD K8 cpus
  x86, sched: Workaround broken sched domain creation for AMD Magny-Cours
  x86, mcheck: Use correct cpumask for shared bank4
  x86, cacheinfo: Fixup L3 cache information for AMD multi-node processors
  x86: Fix CPU llc_shared_map information for AMD Magny-Cours
  x86, msr: Fix msr-reg.S compilation with gas 2.16.1, on 32-bit too
  x86: Move kernel_fpu_using to irq_fpu_usable in asm/i387.h
  x86, msr: fix msr-reg.S compilation with gas 2.16.1
  x86, msr: Export the register-setting MSR functions via /dev/*/msr
  x86, msr: Create _on_cpu helpers for {rw,wr}msr_safe_regs()
  x86, msr: Have the _safe MSR functions return -EIO, not -EFAULT
  x86, msr: CFI annotations, cleanups for msr-reg.S
  x86, asm: Make _ASM_EXTABLE() usable from assembly code
  x86, asm: Add 32-bit versions of the combined CFI macros
  x86, AMD: Disable wrongly set X86_FEATURE_LAHF_LM CPUID bit
  x86, msr: Rewrite AMD rd/wrmsr variants
  x86, msr: Add rd/wrmsr interfaces with preset registers
  x86: add specific support for Intel Atom architecture
  ...
2009-09-14 07:57:32 -07:00
Ben Hutchings 5367b6887e x86: Fix code patching for paravirt-alternatives on 486
As reported in <http://bugs.debian.org/511703> and
<http://bugs.debian.org/515982>, kernels with paravirt-alternatives
enabled crash in text_poke_early() on at least some 486-class
processors.

The problem is that text_poke_early() itself uses inline functions
affected by paravirt-alternatives and so will modify instructions that
have already been prefetched.  Pentium and later processors will
invalidate the prefetched instructions in this case, but 486-class
processors do not.

Change sync_core() to limit prefetching on 486-class (and 386-class)
processors, and move the call to sync_core() above the call to the
modifiable local_irq_restore().

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
LKML-Reference: <1252547631.3423.134.camel@localhost>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2009-09-10 16:50:19 -07:00
Jan Beulich 8b5a10fc6f x86: properly annotate alternatives.c
Some of the NOPs tables aren't used on 64-bits, quite some code and
data is needed post-init for module loading only, and a couple of
functions aren't used outside that file (i.e. can be static, and don't
need to be exported).

The change to __INITDATA/__INITRODATA is needed to avoid an assembler
warning.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <4A8BC8A00200007800010823@vpn.id2.novell.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2009-08-21 15:30:12 -07:00
Masami Hiramatsu 7cf4942704 x86: expand irq-off region in text_poke()
Expand irq-off region to cover fixmap using code and cache synchronizing.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
LKML-Reference: <49B54688.8090403@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-10 16:24:23 +01:00
Masami Hiramatsu 78ff7fae04 x86: implement atomic text_poke() via fixmap
Use fixmaps instead of vmap/vunmap in text_poke() for avoiding
page allocation and delayed unmapping.

At the result of above change, text_poke() becomes atomic and can be called
from stop_machine() etc.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
LKML-Reference: <49B14352.2040705@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-06 16:49:01 +01:00
Masami Hiramatsu 3945dab45a tracing, Text Edit Lock - SMP alternatives support
Use the mutual exclusion provided by the text edit lock in alternatives code.
Since alternative_smp_* will be called from module init code, etc,
we'd better protect it from other subsystems.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
LKML-Reference: <49B14332.9030109@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-06 16:49:00 +01:00
H. Peter Anvin 2e22ea7cea Merge branch 'x86/core' into x86/mce2 2009-03-03 21:05:42 -08:00
Peter Zijlstra 34754b69a6 x86: make vmap yell louder when it is used under irqs_disabled()
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-25 16:38:34 +01:00
Andi Kleen 123aa76ec0 x86, mce: don't disable machine checks during code patching
Impact: low priority bug fix

This removes part of a a patch I added myself some time ago. After some
consideration the patch was a bad idea. In particular it stopped machine check
exceptions during code patching.

To quote the comment:

        * MCEs only happen when something got corrupted and in this
        * case we must do something about the corruption.
        * Ignoring it is worse than a unlikely patching race.
        * Also machine checks tend to be broadcast and if one CPU
        * goes into machine check the others follow quickly, so we don't
        * expect a machine check to cause undue problems during to code
        * patching.

So undo the machine check related parts of
8f4e956b31 NMIs are still disabled.

This only removes code, the only additions are a new comment.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2009-02-17 15:32:38 -08:00
Thomas Gleixner 649c6653fa x86: improve UP kernel when CPU-hotplug and SMP is enabled
num_possible_cpus() can be > 1 when disabled CPUs have been accounted.

Disabled CPUs are not in the cpu_present_map, so we can use
num_present_cpus() as a safe indicator to switch to UP alternatives.

Reported-by: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-13 10:33:46 +02:00
Ingo Molnar e496e3d645 Merge branches 'x86/alternatives', 'x86/cleanups', 'x86/commandline', 'x86/crashdump', 'x86/debug', 'x86/defconfig', 'x86/doc', 'x86/exports', 'x86/fpu', 'x86/gart', 'x86/idle', 'x86/mm', 'x86/mtrr', 'x86/nmi-watchdog', 'x86/oprofile', 'x86/paravirt', 'x86/reboot', 'x86/sparse-fixes', 'x86/tsc', 'x86/urgent' and 'x86/vmalloc' into x86-v28-for-linus-phase1 2008-10-06 18:17:07 +02:00
H. Peter Anvin f31d731e44 x86: use X86_FEATURE_NOPL in alternatives
Use X86_FEATURE_NOPL to determine if it is safe to use P6 NOPs in
alternatives.  Also, replace table and loop with simple if statement.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2008-09-05 16:14:01 -07:00
Mathieu Desnoyers f88f07e0f0 x86: alternatives : fix LOCK_PREFIX race with preemptible kernel and CPU hotplug
If a kernel thread is preempted in single-cpu mode right after the NOP (nop
about to be turned into a lock prefix), then we CPU hotplug a CPU, and then the
thread is scheduled back again, a SMP-unsafe atomic operation will be used on
shared SMP variables, leading to corruption. No corruption would happen in the
reverse case : going from SMP to UP is ok because we split a bit instruction
into tiny pieces, which does not present this condition.

Changing the 0x90 (single-byte nop) currently used into a 0x3E DS segment
override prefix should fix this issue. Since the default of the atomic
instructions is to use the DS segment anyway, it should not affect the
behavior.

The exception to this are references that use ESP/RSP and EBP/RBP as
the base register (they will use the SS segment), however, in Linux
(a) DS == SS at all times, and (b) we do not distinguish between
segment violations reported as #SS as opposed to #GP, so there is no
need to disassemble the instruction to figure out the suitable segment.

This patch assumes that the 0x3E prefix will leave atomic operations as-is (thus
assuming they normally touch data in the DS segment). Since there seem to be no
obvious ill-use of other segment override prefixes for atomic operations, it
should be safe. It can be verified with a quick

grep -r LOCK_PREFIX include/asm-x86/
grep -A 1 -r LOCK_PREFIX arch/x86/

Taken from

This source :
AMD64 Architecture Programmer's Manual Volume 3: General-Purpose and System
Instructions
States
"Instructions that Reference a Non-Stack Segment—If an instruction encoding
references any base register other than rBP or rSP, or if an instruction
contains an immediate offset, the default segment is the data segment (DS).
These instructions can use the segment-override prefix to select one of the
non-default segments, as shown in Table 1-5."

Therefore, forcing the DS segment on the atomic operations, which already use
the DS segment, should not change.

This source :
http://wiki.osdev.org/X86_Instruction_Encoding
States
"In 64-bit the CS, SS, DS and ES segment overrides are ignored."

Confirmed by "AMD 64-Bit Technology" A.7
http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/x86-64_overview.pdf

"In 64-bit mode, the DS, ES, SS and CS segment-override prefixes have no effect.
These four prefixes are no longer treated as segment-override prefixes in the
context of multipleprefix rules. Instead, they are treated as null prefixes."

This patch applies to 2.6.27-rc2, but would also have to be applied to earlier
kernels (2.6.26, 2.6.25, ...).

Performance impact of the fix : tests done on "xaddq" and "xaddl" shows it
actually improves performances on Intel Xeon, AMD64, Pentium M. It does not
change the performance on Pentium II, Pentium 3 and Pentium 4.

Xeon E5405 2.0GHz :
NR_TESTS                                    10000000
test empty cycles :                        162207948
test test 1-byte nop xadd cycles :         170755422
test test DS override prefix xadd cycles : 170000118 *
test test LOCK xadd cycles :               472012134

AMD64 2.0GHz :
NR_TESTS                                    10000000
test empty cycles :                        146674549
test test 1-byte nop xadd cycles :         150273860
test test DS override prefix xadd cycles : 149982382 *
test test LOCK xadd cycles :               270000690

Pentium 4 3.0GHz
NR_TESTS                                    10000000
test empty cycles :                        290001195
test test 1-byte nop xadd cycles :         310000560
test test DS override prefix xadd cycles : 310000575 *
test test LOCK xadd cycles :              1050103740

Pentium M 2.0GHz
NR_TESTS 10000000
test empty cycles :                        180000523
test test 1-byte nop xadd cycles :         320000345
test test DS override prefix xadd cycles : 310000374 *
test test LOCK xadd cycles :               480000357

Pentium 3 550MHz
NR_TESTS                                    10000000
test empty cycles :                        510000231
test test 1-byte nop xadd cycles :         620000128
test test DS override prefix xadd cycles : 620000110 *
test test LOCK xadd cycles :               800000088

Pentium II 350MHz
NR_TESTS                                    10000000
test empty cycles :                        200833494
test test 1-byte nop xadd cycles :         340000130
test test DS override prefix xadd cycles : 340000126 *
test test LOCK xadd cycles :               530000078

Speed test modules can be found at
http://ltt.polymtl.ca/svn/trunk/tests/kernel/test-prefix-speed-32.c
http://ltt.polymtl.ca/svn/trunk/tests/kernel/test-prefix-speed.c

Macro-benchmarks

2.0GHz E5405 Core 2 dual Quad-Core Xeon

Summary

* replace smp lock prefixes with DS segment selector prefixes
                  no lock prefix (s)   with lock prefix (s)    Speedup
make -j1 kernel/      33.94 +/- 0.07         34.91 +/- 0.27      2.8 %
hackbench 50           2.99 +/- 0.01          3.74 +/- 0.01     25.1 %

* replace smp lock prefixes with 0x90 nops
                  no lock prefix (s)   with lock prefix (s)    Speedup
make -j1 kernel/      34.16 +/- 0.32         34.91 +/- 0.27      2.2 %
hackbench 50           3.00 +/- 0.01          3.74 +/- 0.01     24.7 %

Detail :

1 CPU, replace smp lock prefixes with DS segment selector prefixes

make -j1 kernel/

real	0m34.067s
user	0m30.630s
sys	0m2.980s

real	0m33.867s
user	0m30.582s
sys	0m3.024s

real	0m33.939s
user	0m30.738s
sys	0m2.876s

real	0m33.913s
user	0m30.806s
sys	0m2.808s

avg : 33.94s
std. dev. : 0.07s

hackbench 50

Time: 2.978
Time: 2.982
Time: 3.010
Time: 2.984
Time: 2.982

avg : 2.99
std. dev. : 0.01

1 CPU, noreplace-smp

make -j1 kernel/

real	0m35.326s
user	0m30.630s
sys	0m3.260s

real	0m34.325s
user	0m30.802s
sys	0m3.084s

real	0m35.568s
user	0m30.722s
sys	0m3.168s

real	0m34.435s
user	0m30.886s
sys	0m2.996s

avg.: 34.91s
std. dev. : 0.27s

hackbench 50

Time: 3.733
Time: 3.750
Time: 3.761
Time: 3.737
Time: 3.741

avg : 3.74
std. dev. : 0.01

1 CPU, replace smp lock prefixes with 0x90 nops

make -j1 kernel/

real	0m34.139s
user	0m30.782s
sys	0m2.820s

real	0m34.010s
user	0m30.630s
sys	0m2.976s

real	0m34.777s
user	0m30.658s
sys	0m2.916s

real	0m33.924s
user	0m30.634s
sys	0m2.924s

real	0m33.962s
user	0m30.774s
sys	0m2.800s

real	0m34.141s
user	0m30.770s
sys	0m2.828s

avg : 34.16
std. dev. : 0.32

hackbench 50

Time: 2.999
Time: 2.994
Time: 3.004
Time: 2.991
Time: 2.988

avg : 3.00
std. dev. : 0.01

I did more runs (20 runs of each) to compare the nop case to the DS
prefix case. Results in seconds. They actually does not seems to show a
significant difference.

NOP

34.155
33.955
34.012
35.299
35.679
34.141
33.995
35.016
34.254
33.957
33.957
34.008
35.013
34.494
33.893
34.295
34.314
34.854
33.991
34.132

DS

34.080
34.304
34.374
35.095
34.291
34.135
33.940
34.208
35.276
34.288
33.861
33.898
34.610
34.709
33.851
34.256
35.161
34.283
33.865
35.078

Used http://www.graphpad.com/quickcalcs/ttest1.cfm?Format=C to do the
T-test (yeah, I'm lazy) :

 Group      Group One (DS prefix)       Group Two (nops)
 Mean                    34.37815               34.37070
 SD                       0.46108                0.51905
 SEM                      0.10310                0.11606
 N                             20                     20

P value and statistical significance:
  The two-tailed P value equals 0.9620
  By conventional criteria, this difference is considered to be not statistically significant.

Confidence interval:
  The mean of Group One minus Group Two equals 0.00745
  95% confidence interval of this difference: From -0.30682 to 0.32172

Intermediate values used in calculations:
  t = 0.0480
  df = 38
  standard error of difference = 0.155

So, unless these calculus are completely bogus, the difference between the nop
and the DS case seems not to be statistically significant.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: H. Peter Anvin <hpa@zytor.com>
CC: Linus Torvalds <torvalds@linux-foundation.org>
CC: Jeremy Fitzhardinge <jeremy@goop.org>
CC: Roland McGrath <roland@redhat.com>
CC: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
CC: Steven Rostedt <srostedt@redhat.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: David Miller <davem@davemloft.net>
CC: Ulrich Drepper <drepper@redhat.com>
CC: Rusty Russell <rusty@rustcorp.com.au>
CC: Gregory Haskins <ghaskins@novell.com>
CC: Arnaldo Carvalho de Melo <acme@redhat.com>
CC: "Luis Claudio R. Goncalves" <lclaudio@uudg.org>
CC: Clark Williams <williams@redhat.com>
CC: Christoph Lameter <cl@linux-foundation.org>
CC: Andi Kleen <andi@firstfloor.org>
CC: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2008-08-15 12:46:28 -07:00
Pekka Paalanen 2f1dafe50c x86: fix SMP alternatives: use mutex instead of spinlock, text_poke is sleepable
text_poke is sleepable.
The original fix by Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>.

Signed-off-by: Pekka Paalanen <pq@iki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 21:56:52 +02:00
Steven Rostedt dfa60aba04 ftrace: use nops instead of jmp
This patch patches the call to mcount with nops instead
of a jmp over the mcount call.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 20:33:28 +02:00
Ingo Molnar 00c6b2d5d7 x86: harden kernel code patching
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-25 19:54:07 +02:00