This patch adds support for building PMU driver as module. It exports
the functions perf_pmu_{register,unregister}() and adds reference tracking
for the PMU driver module.

When the PMU driver is built as a module, each active event of the PMU
holds a reference to the driver module.
Signed-off-by: NYan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1395133004-23205-1-git-send-email-zheng.z.yan@intel.com
Cc: eranian@google.com
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Signed-off-by: NIngo Molnar <mingo@kernel.org>

CPUs which should support the RAPL counters according to
Family/Model/Stepping may still issue #GP when attempting to access
the RAPL MSRs. This may happen when Linux is running under KVM and
we are passing-through host F/M/S data, for example. Use rdmsrl_safe
to first access the RAPL_POWER_UNIT MSR; if this fails, do not
attempt to use this PMU.
Signed-off-by: NVenkatesh Srinivas <venkateshs@google.com>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1394739386-22260-1-git-send-email-venkateshs@google.com
Cc: zheng.z.yan@intel.com
Cc: eranian@google.com
Cc: ak@linux.intel.com
Cc: linux-kernel@vger.kernel.org
[ The patch also silently fixes another bug: rapl_pmu_init() didn't handle the memory alloc failure case previously. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Merge branch 'uprobes/core' of git://git.kernel.org/pub/scm/linux/kernel/git/oleg/misc into perf/core

Pull uprobes fixes and cleanups from Oleg Nesterov:

  "Any probed jmp/call can kill the application, see the changelog in 11/15."
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Change branch_setup_xol_ops() to simply use opc1 = OPCODE2(insn) - 0x10
if OPCODE1() == 0x0f; this matches the "short" jmp which checks the same
condition.

Thanks to lib/insn.c, it does the rest correctly. branch->ilen/offs are
correct no matter if this jmp is "near" or "short".
Reported-by: NJonathan Lebon <jlebon@redhat.com>
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NJim Keniston <jkenisto@us.ibm.com>

Teach branch_emulate_op() to emulate the conditional "short" jmp's which
check regs->flags.

Note: this doesn't support jcxz/jcexz, loope/loopz, and loopne/loopnz.
They all are rel8 and thus they can't trigger the problem, but perhaps
we will add the support in future just for completeness.
Reported-by: NJonathan Lebon <jlebon@redhat.com>
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NJim Keniston <jkenisto@us.ibm.com>

See the previous "Emulate unconditional relative jmp's" which explains
why we can not execute "jmp" out-of-line, the same applies to "call".

Emulating of rip-relative call is trivial, we only need to additionally
push the ret-address. If this fails, we execute this instruction out of
line and this should trigger the trap, the probed application should die
or the same insn will be restarted if a signal handler expands the stack.
We do not even need ->post_xol() for this case.

But there is a corner (and almost theoretical) case: another thread can
expand the stack right before we execute this insn out of line. In this
case it hit the same problem we are trying to solve. So we simply turn
the probed insn into "call 1f; 1:" and add ->post_xol() which restores
->sp and restarts.

Many thanks to Jonathan who finally found the standalone reproducer,
otherwise I would never resolve the "random SIGSEGV's under systemtap"
bug-report. Now that the problem is clear we can write the simplified
test-case:

	void probe_func(void), callee(void);

	int failed = 1;

	asm (
		".text\n"
		".align 4096\n"
		".globl probe_func\n"
		"probe_func:\n"
		"call callee\n"
		"ret"
	);

	/*
	 * This assumes that:
	 *
	 *	- &probe_func = 0x401000 + a_bit, aligned = 0x402000
	 *
	 *	- xol_vma->vm_start = TASK_SIZE_MAX - PAGE_SIZE = 0x7fffffffe000
	 *	  as xol_add_vma() asks; the 1st slot = 0x7fffffffe080
	 *
	 * so we can target the non-canonical address from xol_vma using
	 * the simple math below, 100 * 4096 is just the random offset
	 */
	asm (".org . + 0x800000000000 - 0x7fffffffe080 - 5 - 1  + 100 * 4096\n");

	void callee(void)
	{
		failed = 0;
	}

	int main(void)
	{
		probe_func();
		return failed;
	}

It SIGSEGV's if you probe "probe_func" (although this is not very reliable,
randomize_va_space/etc can change the placement of xol area).

Note: as Denys Vlasenko pointed out, amd and intel treat "callw" (0x66 0xe8)
differently. This patch relies on lib/insn.c and thus implements the intel's
behaviour: 0x66 is simply ignored. Fortunately nothing sane should ever use
this insn, so we postpone the fix until we decide what should we do; emulate
or not, support or not, etc.
Reported-by: NJonathan Lebon <jlebon@redhat.com>
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NJim Keniston <jkenisto@us.ibm.com>

Finally we can kill the ugly (and very limited) code in __skip_sstep().
Just change branch_setup_xol_ops() to treat "nop" as jmp to the next insn.

Thanks to lib/insn.c, it is clever enough. OPCODE1() == 0x90 includes
"(rep;)+ nop;" at least, and (afaics) much more.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NJim Keniston <jkenisto@us.ibm.com>

Currently we always execute all insns out-of-line, including relative
jmp's and call's. This assumes that even if regs->ip points to nowhere
after the single-step, default_post_xol_op(UPROBE_FIX_IP) logic will
update it correctly.

However, this doesn't work if this regs->ip == xol_vaddr + insn_offset
is not canonical. In this case CPU generates #GP and general_protection()
kills the task which tries to execute this insn out-of-line.

Now that we have uprobe_xol_ops we can teach uprobes to emulate these
insns and solve the problem. This patch adds branch_xol_ops which has
a single branch_emulate_op() hook, so far it can only handle rel8/32
relative jmp's.

TODO: move ->fixup into the union along with rip_rela_target_address.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reported-by: NJonathan Lebon <jlebon@redhat.com>
Reviewed-by: NJim Keniston <jkenisto@us.ibm.com>

uprobes/x86: Introduce sizeof_long(), cleanup adjust_ret_addr() and arch_uretprobe_hijack_return_addr()

1. Add the trivial sizeof_long() helper and change other callers of
   is_ia32_task() to use it.

   TODO: is_ia32_task() is not what we actually want, TS_COMPAT does
   not necessarily mean 32bit. Fortunately syscall-like insns can't be
   probed so it actually works, but it would be better to rename and
   use is_ia32_frame().

2. As Jim pointed out "ncopied" in arch_uretprobe_hijack_return_addr()
   and adjust_ret_addr() should be named "nleft". And in fact only the
   last copy_to_user() in arch_uretprobe_hijack_return_addr() actually
   needs to inspect the non-zero error code.

TODO: adjust_ret_addr() should die. We can always calculate the value
we need to write into *regs->sp, just UPROBE_FIX_CALL should record
insn->length.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NJim Keniston <jkenisto@us.ibm.com>

SIGILL after the failed arch_uprobe_post_xol() should only be used as
a last resort, we should try to restart the probed insn if possible.

Currently only adjust_ret_addr() can fail, and this can only happen if
another thread unmapped our stack after we executed "call" out-of-line.
Most probably the application if buggy, but even in this case it can
have a handler for SIGSEGV/etc. And in theory it can be even correct
and do something non-trivial with its memory.

Of course we can't restart unconditionally, so arch_uprobe_post_xol()
does this only if ->post_xol() returns -ERESTART even if currently this
is the only possible error.

default_post_xol_op(UPROBE_FIX_CALL) can always restart, but as Jim
pointed out it should not forget to pop off the return address pushed
by this insn executed out-of-line.

Note: this is not "perfect", we do not want the extra handler_chain()
after restart, but I think this is the best solution we can realistically
do without too much uglifications.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: NJim Keniston <jkenisto@us.ibm.com>

Currently the error from arch_uprobe_post_xol() is silently ignored.
This doesn't look good and this can lead to the hard-to-debug problems.

1. Change handle_singlestep() to loudly complain and send SIGILL.

   Note: this only affects x86, ppc/arm can't fail.

2. Change arch_uprobe_post_xol() to call arch_uprobe_abort_xol() and
   avoid TF games if it is going to return an error.

   This can help to to analyze the problem, if nothing else we should
   not report ->ip = xol_slot in the core-file.

   Note: this means that handle_riprel_post_xol() can be called twice,
   but this is fine because it is idempotent.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: NJim Keniston <jkenisto@us.ibm.com>

arch_uprobe_analyze_insn() calls handle_riprel_insn() at the start,
but only "0xff" and "default" cases need the UPROBE_FIX_RIP_ logic.
Move the callsite into "default" case and change the "0xff" case to
fall-through.

We are going to add the various hooks to handle the rip-relative
jmp/call instructions (and more), we need this change to enforce the
fact that the new code can not conflict with is_riprel_insn() logic
which, after this change, can only be used by default_xol_ops.

Note: arch_uprobe_abort_xol() still calls handle_riprel_post_xol()
directly. This is fine unless another _xol_ops we may add later will
need to reuse "UPROBE_FIX_RIP_AX|UPROBE_FIX_RIP_CX" bits in ->fixup.
In this case we can add uprobe_xol_ops->abort() hook, which (perhaps)
we will need anyway in the long term.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NJim Keniston <jkenisto@us.ibm.com>
Reviewed-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

Introduce arch_uprobe->ops pointing to the "struct uprobe_xol_ops",
move the current UPROBE_FIX_{RIP*,IP,CALL} code into the default
set of methods and change arch_uprobe_pre/post_xol() accordingly.

This way we can add the new uprobe_xol_ops's to handle the insns
which need the special processing (rip-relative jmp/call at least).
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NJim Keniston <jkenisto@us.ibm.com>
Reviewed-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

No functional changes. Preparation to simplify the review of the next
change. Just reorder the code in arch_uprobe_pre/post_xol() functions
so that UPROBE_FIX_{RIP_*,IP,CALL} logic goes to the end.

Also change arch_uprobe_pre_xol() to use utask instead of autask, to
make the code more symmetrical with arch_uprobe_post_xol().
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: NJim Keniston <jkenisto@us.ibm.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

Cosmetic. Move pre_xol_rip_insn() and handle_riprel_post_xol() up to
the closely related handle_riprel_insn(). This way it is simpler to
read and understand this code, and this lessens the number of ifdef's.

While at it, update the comment in handle_riprel_post_xol() as Jim
suggested.

TODO: rename them somehow to make the naming consistent.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: NJim Keniston <jkenisto@us.ibm.com>

Kill the "mm->context.ia32_compat" check in handle_riprel_insn(), if
it is true insn_rip_relative() must return false. validate_insn_bits()
passed "ia32_compat" as !x86_64 to insn_init(), and insn_rip_relative()
checks insn->x86_64.

Also, remove the no longer needed "struct mm_struct *mm" argument and
the unnecessary "return" at the end.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: NJim Keniston <jkenisto@us.ibm.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

No functional changes, preparation.

Shift the code from prepare_fixups() to arch_uprobe_analyze_insn()
with the following modifications:

	- Do not call insn_get_opcode() again, it was already called
	  by validate_insn_bits().

	- Move "case 0xea" up. This way "case 0xff" can fall through
	  to default case.

	- change "case 0xff" to use the nested "switch (MODRM_REG)",
	  this way the code looks a bit simpler.

	- Make the comments look consistent.

While at it, kill the initialization of rip_rela_target_address and
->fixups, we can rely on kzalloc(). We will add the new members into
arch_uprobe, it would be better to assume that everything is zero by
default.

TODO: cleanup/fix the mess in validate_insn_bits() paths:

	- validate_insn_64bits() and validate_insn_32bits() should be
	  unified.

	- "ifdef" is not used consistently; if good_insns_64 depends
	  on CONFIG_X86_64, then probably good_insns_32 should depend
	  on CONFIG_X86_32/EMULATION

	- the usage of mm->context.ia32_compat looks wrong if the task
	  is TIF_X32.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: NJim Keniston <jkenisto@us.ibm.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

UPROBE_COPY_INSN, UPROBE_SKIP_SSTEP, and uprobe->flags must die. This
patch kills UPROBE_SKIP_SSTEP. I never understood why it was added;
not only it doesn't help, it harms.

It can only help to avoid arch_uprobe_skip_sstep() if it was already
called before and failed. But this is ugly, if we want to know whether
we can emulate this instruction or not we should do this analysis in
arch_uprobe_analyze_insn(), not when we hit this probe for the first
time.

And in fact this logic is simply wrong. arch_uprobe_skip_sstep() can
fail or not depending on the task/register state, if this insn can be
emulated but, say, put_user() fails we need to xol it this time, but
this doesn't mean we shouldn't try to emulate it when this or another
thread hits this bp next time.

And this is the actual reason for this change. We need to emulate the
"call" insn, but push(return-address) can obviously fail.

Per-arch notes:

	x86: __skip_sstep() can only emulate "rep;nop". With this
	     change it will be called every time and most probably
	     for no reason.

	     This will be fixed by the next changes. We need to
	     change this suboptimal code anyway.

	arm: Should not be affected. It has its own "bool simulate"
	     flag checked in arch_uprobe_skip_sstep().

	ppc: Looks like, it can emulate almost everything. Does it
	     actually need to record the fact that emulate_step()
	     failed? Hopefully not. But if yes, it can add the ppc-
	     specific flag into arch_uprobe.

TODO: rename arch_uprobe_skip_sstep() to arch_uprobe_emulate_insn(),
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: NDavid A. Long <dave.long@linaro.org>
Reviewed-by: NJim Keniston <jkenisto@us.ibm.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>

Current kprobes in-kernel page fault handler doesn't
expect that its single-stepping can be interrupted by
an NMI handler which may cause a page fault(e.g. perf
with callback tracing).

In that case, the page-fault handled by kprobes and it
misunderstands the page-fault has been caused by the
single-stepping code and tries to recover IP address
to probed address.

But the truth is the page-fault has been caused by the
NMI handler, and do_page_fault failes to handle real
page fault because the IP address is modified and
causes Kernel BUGs like below.

 ----
 [ 2264.726905] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
 [ 2264.727190] IP: [<ffffffff813c46e0>] copy_user_generic_string+0x0/0x40

To handle this correctly, I fixed the kprobes fault
handler to ensure the faulted ip address is its own
single-step buffer instead of checking current kprobe
state.
Signed-off-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Sandeepa Prabhu <sandeepa.prabhu@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: fche@redhat.com
Cc: systemtap@sourceware.org
Link: http://lkml.kernel.org/r/20140417081644.26341.52351.stgit@ltc230.yrl.intra.hitachi.co.jpSigned-off-by: NIngo Molnar <mingo@kernel.org>

Merge tag 'perf-core-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf into perf/core

Pull perf/core improvements and fixes from Jiri Olsa:

User visible changes:

  * Add --percentage option to control absolute/relative percentage output (Namhyung Kim)

Plumbing changes:

  * Add --list-cmds to 'kmem', 'mem', 'lock' and 'sched', for use by completion scripts (Ramkumar Ramachandra)
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Pull x86 fixes from Ingo Molnar:
 "Various fixes:

   - reboot regression fix
   - build message spam fix
   - GPU quirk fix
   - 'make kvmconfig' fix

  plus the wire-up of the renameat2() system call on i386"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86: Remove the PCI reboot method from the default chain
  x86/build: Supress "Nothing to be done for ..." messages
  x86/gpu: Fix sign extension issue in Intel graphics stolen memory quirks
  x86/platform: Fix "make O=dir kvmconfig"
  i386: Wire up the renameat2() syscall

Pull perf fixes from Ingo Molnar:
 "Tooling fixes, plus a simple hardware-enablement patch for the Intel
  RAPL PMU (energy use measurement) on Haswell CPUs, which I hope is
  still fine at this stage"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf tools: Instead of redirecting flex output, use -o
  perf tools: Fix double free in perf test 21 (code-reading.c)
  perf stat: Initialize statistics correctly
  perf bench: Set more defaults in the 'numa' suite
  perf bench: Fix segfault at the end of an 'all' execution
  perf bench: Update manpage to mention numa and futex
  perf probe: Use dwarf_getcfi_elf() instead of dwarf_getcfi()
  perf probe: Fix to handle errors in line_range searching
  perf probe: Fix --line option behavior
  perf tools: Pick up libdw without explicit LIBDW_DIR
  MAINTAINERS: Change e-mail to kernel.org one
  perf callchains: Disable unwind libraries when libelf isn't found
  tools lib traceevent: Do not call warning() directly
  tools lib traceevent: Print event name when show warning if possible
  perf top: Fix documentation of invalid -s option
  perf/x86: Enable DRAM RAPL support on Intel Haswell

Pull irq fix from Ingo Molnar:
 "ARM VIC (Vectored Irq Controller) irqchip driver fix"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip: vic: Properly chain the cascaded IRQs

Pull locking fixes from Ingo Molnar:
 "liblockdep fixes and mutex debugging fixes"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/mutex: Fix debug_mutexes
  tools/liblockdep: Add proper versioning to the shared obj
  tools/liblockdep: Ignore asmlinkage and visible

Pull fbdev fixes from Tomi Valkeinen:
 - fix build errors for bf54x-lq043fb and imxfb
 - fbcon fix for da8xx-fb
 - omapdss fixes for hdmi audio, irq handling and fclk calculation

* tag 'fbdev-fixes-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tomba/linux:
  video: bf54x-lq043fb: fix build error
  OMAPDSS: Change struct reg_field to dispc_reg_field
  OMAPDSS: Take pixelclock unit change into account in hdmi_compute_acr()
  OMAPDSS: fix shared irq handlers
  video: imxfb: Select LCD_CLASS_DEVICE unconditionally
  OMAPDSS: fix rounding when calculating fclk rate
  video: da8xx-fb: Fix casting of info->pseudo_palette

Pull pincontrol fixes from Linus Walleij:
 "A first set of pin control fixes for the v3.15 series:

   - Fix a couple of barnsjukdomar on the Rockchip driver.

   - Remove an idiotic debug print I happened to leave behind in the
     Nomadik driver.

   - Fixup the Qualcomm MSM interrupt handling code for the TLMM v2.

   - Three patches renaming the Broadcom Capri driver to BCM28155.  This
     has been falling between the chairs for some time due to some
     cross-tree synchronization misunderstandings, now I'm fed up with
     this and just rename it in this -rc1 phase"

* tag 'pinctrl-v3.15-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: fix typo in bindings documentation
  Update bcm_defconfig with new pinctrl CONFIG
  pinctrl: Rename Broadcom Capri pinctrl driver
  pinctrl: msm: Correct interrupt code for TLMM v2
  pinctrl: nomadik: delete stray debug print
  pinctrl: rockchip: handle first half of rk3188-bank0 correctly
  pinctrl: rockchip: add return value to rockchip_set_mux
  pinctrl: rockchip: fix offset of mux registers for rk3188

Pull s390 patches from Martin Schwidefsky:
 "An update to the oops output with additional information about the
  crash.  The renameat2 system call is enabled.  Two patches in regard
  to the PTR_ERR_OR_ZERO cleanup.  And a bunch of bug fixes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/sclp_cmd: replace PTR_RET with PTR_ERR_OR_ZERO
  s390/sclp: replace PTR_RET with PTR_ERR_OR_ZERO
  s390/sclp_vt220: Fix kernel panic due to early terminal input
  s390/compat: fix typo
  s390/uaccess: fix possible register corruption in strnlen_user_srst()
  s390: add 31 bit warning message
  s390: wire up sys_renameat2
  s390: show_registers() should not map user space addresses to kernel symbols
  s390/mm: print control registers and page table walk on crash
  s390/smp: fix smp_stop_cpu() for !CONFIG_SMP
  s390: fix control register update

Pull itanium erratum fix from Tony Luck:
 "Small workaround for a rare, but annoying, erratum #237"

* tag 'please-pull-ia64-erratum' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux:
  [IA64] Change default PSR.ac from '1' to '0' (Fix erratum #237)

April 2014 Itanium processor specification update:

http://www.intel.com/content/www/us/en/processors/itanium/itanium-specification-update.html

describes this erratum:

=========================================================================
237. Under a complex set of conditions, store to load forwarding for a
sub 8-byte load may complete incorrectly

Problem: A load instruction may complete incorrectly when a code sequence
using 4-byte or smaller load and store operations to the same address
is executed in combination with specific timing of all the following
concurrent conditions: store to load forwarding, alignment checking
enabled, a mis-predicted branch, and complex cache utilization activity.

Implication: The affected sub 8-byte instruction may complete
incorrectly resulting in unpredictable system behavior. There is an
extremely low probability of exposure due to the significant number of
complex microarchitectural concurrent conditions required to encounter
the erratum.

Workaround: Set PSR.ac = 0 to completely avoid the erratum. Disabling
Hyper-Threading will significantly reduce exposure to the conditions
that contribute to encountering the erratum.

Status: See the Summary Table of Changes for the affected steppings.
=========================================================================

[Table of changes essentially lists all models from McKinley to Tukwila]

The PSR.ac bit controls whether the processor will always generate
an unaligned reference trap (0x5a00) for a misaligned data access
(when PSR.ac=1) or if it will let the access succeed when running
on a cpu that implements logic to handle some unaligned accesses.

Way back in 2008 in commit b704882e
  [IA64] Rationalize kernel mode alignment checking
we made the decision to always enable strict checking. We were
already doing so in trap/interrupt context because the common
preamble code set this bit - but the rest of supervisor code
(and by inheritance user code) ran with PSR.ac=0.

We now reverse that decision and set PSR.ac=0 everywhere in the
kernel (also inherited by user processes). This will avoid the
erratum using the method described in the Itanium specification
update.  Net effect for users is that the processor will handle
unaligned access when it can (typically with a tiny performance
bubble in the pipeline ... but much less invasive than taking a
trap and having the OS perform the access).
Signed-off-by: NTony Luck <tony.luck@intel.com>

Signed-off-by: NRamkumar Ramachandra <artagnon@gmail.com>
Acked-by: NDavid Ahern <dsahern@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1394853474-31019-5-git-send-email-artagnon@gmail.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NJiri Olsa <jolsa@redhat.com>

Signed-off-by: NRamkumar Ramachandra <artagnon@gmail.com>
Acked-by: NDavid Ahern <dsahern@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1394853474-31019-4-git-send-email-artagnon@gmail.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NJiri Olsa <jolsa@redhat.com>

Signed-off-by: NRamkumar Ramachandra <artagnon@gmail.com>
Acked-by: NDavid Ahern <dsahern@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1394853474-31019-3-git-send-email-artagnon@gmail.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NJiri Olsa <jolsa@redhat.com>

Signed-off-by: NRamkumar Ramachandra <artagnon@gmail.com>
Acked-by: NDavid Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1394853474-31019-2-git-send-email-artagnon@gmail.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NJiri Olsa <jolsa@redhat.com>

Now perf report will show absolute percentage on filter entries by
default.
Suggested-by: NJiri Olsa <jolsa@redhat.com>
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1397145720-8063-8-git-send-email-namhyung@kernel.orgSigned-off-by: NJiri Olsa <jolsa@redhat.com>

Add 'F' hotkey to toggle relative and absolute percentage of filtered
entries.
Suggested-by: NJiri Olsa <jolsa@redhat.com>
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1397145720-8063-7-git-send-email-namhyung@kernel.orgSigned-off-by: NJiri Olsa <jolsa@redhat.com>

Add hist.percentage option for setting default value of the
symbol_conf.filter_relative.  It affects the output of various perf
commands (like perf report, top and diff) only if filter(s) applied.

An user can write .perfconfig file like below to show absolute
percentage of filtered entries by default:

  $ cat ~/.perfconfig
  [hist]
  percentage = absolute

And it can be changed through command line:

  $ perf report --percentage relative
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1397145720-8063-6-git-send-email-namhyung@kernel.orgSigned-off-by: NJiri Olsa <jolsa@redhat.com>

The --percentage option is for controlling overhead percentage
displayed.  It can only receive either of "relative" or "absolute" and
affects -c delta output only.

For more information, please see previous commit same thing done to
"perf report".
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1397145720-8063-5-git-send-email-namhyung@kernel.orgSigned-off-by: NJiri Olsa <jolsa@redhat.com>

The --percentage option is for controlling overhead percentage
displayed.  It can only receive either of "relative" or "absolute".
Move the parser callback function into a common location since it's
used by multiple commands now.

For more information, please see previous commit same thing done to
"perf report".
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1397145720-8063-4-git-send-email-namhyung@kernel.orgSigned-off-by: NJiri Olsa <jolsa@redhat.com>

The --percentage option is for controlling overhead percentage
displayed.  It can only receive either of "relative" or "absolute".

"relative" means it's relative to filtered entries only so that the
sum of shown entries will be always 100%.  "absolute" means it retains
the original value before and after the filter is applied.

  $ perf report -s comm
  # Overhead       Command
  # ........  ............
  #
      74.19%           cc1
       7.61%           gcc
       6.11%            as
       4.35%            sh
       4.14%          make
       1.13%        fixdep
  ...

  $ perf report -s comm -c cc1,gcc --percentage absolute
  # Overhead       Command
  # ........  ............
  #
      74.19%           cc1
       7.61%           gcc

  $ perf report -s comm -c cc1,gcc --percentage relative
  # Overhead       Command
  # ........  ............
  #
      90.69%           cc1
       9.31%           gcc

Note that it has zero effect if no filter was applied.
Suggested-by: NArnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1397145720-8063-3-git-send-email-namhyung@kernel.orgSigned-off-by: NJiri Olsa <jolsa@redhat.com>