KASAN needs to know whether the allocation happens in an IRQ handler.
This lets us strip everything below the IRQ entry point to reduce the
number of unique stack traces needed to be stored.

Move the definition of __irq_entry to <linux/interrupt.h> so that the
users don't need to pull in <linux/ftrace.h>.  Also introduce the
__softirq_entry macro which is similar to __irq_entry, but puts the
corresponding functions to the .softirqentry.text section.
Signed-off-by: NAlexander Potapenko <glider@google.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Let the non boot cpus call into idle with the corresponding hotplug state, so
the hotplug core can handle the further bringup. That's a first step to
convert the boot side of the hotplugged cpus to do all the synchronization
with the other side through the state machine. For now it'll only start the
hotplug thread and kick the full bringup of the cpu.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Rik van Riel <riel@redhat.com>
Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/20160226182341.614102639@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is no need to worry about module and __init text disappearing
case, because that ftrace has a module notifier that is called when
a module is being unloaded and before the text goes away and this
code grabs the ftrace_lock mutex and removes the module functions
from the ftrace list, such that it will no longer do any
modifications to that module's text, the update to make functions
be traced or not is done under the ftrace_lock mutex as well.
And by now, __init section codes should not been modified
by ftrace, because it is black listed in recordmcount.c and
ignored by ftrace.

Link: http://lkml.kernel.org/r/1449367378-29430-3-git-send-email-huawei.libin@huawei.com

Cc: linux-metag@vger.kernel.org
Acked-by: NJames Hogan <james.hogan@imgtec.com>
Suggested-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NLi Bin <huawei.libin@huawei.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Makes it easier to handle init vs core cleanly, though the change is
fairly invasive across random architectures.

It simplifies the rbtree code immediately, however, while keeping the
core data together in the same cachline (now iff the rbtree code is
enabled).
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Most interrupt flow handlers do not use the irq argument. Those few
which use it can retrieve the irq number from the irq descriptor.

Remove the argument.

Search and replace was done with coccinelle and some extra helper
scripts around it. Thanks to Julia for her help!
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Cc: Jiang Liu <jiang.liu@linux.intel.com>

Back in early 2008, 4KiB stack support was added to reduce memory
consumption on workloads with lots of threads, using a separate IRQ
stack per CPU to alleviate stack pressure. However the SMP code added a
year and a half later didn't set up the IRQ stack when bringing up
secondary CPUs, resulting in a crash when SMP is configured with 4KiB
stacks, as soon as the first interrupt arrived on a secondary CPU.

Fix with calls to irq_ctx_exit()/irq_ctx_exit() when bringing up/down a
CPU.
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Cc: linux-metag@vger.kernel.org

This is a preparatory patch for moving irq_data struct members.
Signed-off-by: NJiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>

Signed-off-by: NRichard Weinberger <richard@nod.at>

The 'arg' argument to copy_thread() is only ever used when forking a new
kernel thread. Hence, rename it to 'kthread_arg' for clarity.
Signed-off-by: NAlex Dowad <alexinbeijing@gmail.com>
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>

This commit removes the open-coded CPU-offline notification with new
common code.  This change avoids calling scheduler code using RCU from
an offline CPU that RCU is ignoring.  This commit is compatible with
the existing code in not checking for timeout during a prior offline
for a given CPU.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: <linux-metag@vger.kernel.org>

If an attacker can cause a controlled kernel stack overflow, overwriting
the restart block is a very juicy exploit target.  This is because the
restart_block is held in the same memory allocation as the kernel stack.

Moving the restart block to struct task_struct prevents this exploit by
making the restart_block harder to locate.

Note that there are other fields in thread_info that are also easy
targets, at least on some architectures.

It's also a decent simplification, since the restart code is more or less
identical on all architectures.

[james.hogan@imgtec.com: metag: align thread_info::supervisor_stack]
Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: David Miller <davem@davemloft.net>
Acked-by: NRichard Weinberger <richard@nod.at>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Replace __get_cpu_var uses for address calculation with this_cpu_ptr().
Acked-by: NJames Hogan <james.hogan@imgtec.com>
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NTejun Heo <tj@kernel.org>

Use sigsp() instead of the open coded variant.
Signed-off-by: NRichard Weinberger <richard@nod.at>
Acked-by: NJames Hogan <james.hogan@imgtec.com>

Nothing sets function_trace_stop to disable function tracing anymore.
Remove the check for it in the arch code.
Acked-by: NJames Hogan <james.hogan@imgtec.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

[linux-3.16-rc5/arch/metag/kernel/cachepart.c:102]: (style) Checking if
unsigned variable 'thread_cache_size' is less than zero.

Source code is

        if (thread_cache_size < 0)
            pr_emerg("Can't read %s cache size\n",
                 cache_type ? "DCACHE" : "ICACHE");

but

    unsigned int thread_cache_size;

Function get_thread_cache_size returns an error code
as (unsigned int) -1.

Change get_thread_cache_size() to return signed int, and its result is
stored into signed int variable.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=80361Reported-by: NDavid Binderman <dcb314@hotmail.com>
Signed-off-by: NAndrey Utkin <andrey.krieger.utkin@gmail.com>
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>

Transition to using the new generic PERF_PMU_CAP_NO_INTERRUPT method for
failing a sampling event when no PMU interrupt is available.
Signed-off-by: NVince Weaver <vincent.weaver@maine.edu>
Acked-by: NJames Hogan <james.hogan@imgtec.com>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linux-metag@vger.kernel.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1406150202050.16738@vincent-weaver-1.umelst.maine.eduSigned-off-by: NIngo Molnar <mingo@kernel.org>

Unify the various architectures __dtb_start and __dtb_end definitions
moving them into of_fdt.h.
Signed-off-by: NRob Herring <robh@kernel.org>
Acked-by: NVineet Gupta <vgupta@synopsys.com>
Acked-by: NJames Hogan <james.hogan@imgtec.com>
Tested-by: NMichal Simek <michal.simek@xilinx.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: linux-metag@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux@lists.openrisc.net
Cc: linux-xtensa@linux-xtensa.org
Tested-by: NGrant Likely <grant.likely@linaro.org>
Tested-by: NStephen Chivers <schivers@csc.com>

Use the more generic functions get_signal() signal_setup_done()
for signal delivery.

[James Hogan: avoid reordering get_signal() and restart check.]
Signed-off-by: NRichard Weinberger <richard@nod.at>
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>

There is no point in having an incomplete copy of irq_set_affinity()
for the hotplug irq migration code.

Use the core function instead and while at it switch to
for_each_active_irq()
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: metag <linux-metag@vger.kernel.org>
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>

As the data parameter is not really used by any ftrace_dyn_arch_init,
remove that from ftrace_dyn_arch_init. This also removes the addr
local variable from ftrace_init which is now unused.

Note the documentation was imprecise as it did not suggest to set
(*data) to 0.

Link: http://lkml.kernel.org/r/1393268401-24379-4-git-send-email-jslaby@suse.cz

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-arch@vger.kernel.org
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

No architecture uses the "data" parameter in ftrace_dyn_arch_init() in any
way, it just sets the value to 0. And this is used as a return value
in the caller -- ftrace_init, which just checks the retval against
zero.

Note there is also "return 0" in every ftrace_dyn_arch_init.  So it is
enough to check the retval and remove all the indirect sets of data on
all archs.

Link: http://lkml.kernel.org/r/1393268401-24379-3-git-send-email-jslaby@suse.cz

Cc: linux-arch@vger.kernel.org
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

boot_secondary() is not used outside arch/metag/kernel/smp.c, hence make it
static.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@linux-m68k.org>
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>

We need to export 'cpu_core_map' since the topology_core_cpumask macro
refers to it and is used by certain kernel modules.

Found in allmodconfig build:
  ERROR: "cpu_core_map" [drivers/staging/lustre/lustre/libcfs/libcfs.ko] undefined!
Signed-off-by: NChen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>

Commit 9a46ad6d "smp: make smp_call_function_many() use logic
similar to smp_call_function_single()" has unified the way to handle
single and multiple cross-CPU function calls. Now only one interrupt is
needed for architecture specific code to support generic SMP function
call interfaces, so kill the redundant single function call interrupt.
Signed-off-by: NJiang Liu <liuj97@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Shaohua Li <shli@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jiri Kosina <trivial@kernel.org>
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>

Since commit f6b30d32 (metag: kick: add missing irq_enter/exit to
kick_handler()), the main kick_handler() function deals with setting and
restoring the irq registers pointer. Therefore do_IPI() which is called
indirectly from kick_handler() doesn't need to do that itself any
longer. Therefore remove that code and do_IPI()'s pt_regs argument.
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Cc: linux-metag@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>

Meta has 2 levels of page table so the pmd folds into the pud which
folds into the pgd. Therefore the !pmd check in dma_alloc_init() is dead
code since it essentially checks whether:
  (init_mm->pgd + 0x770) == 0

Remove the check.
Reported-by: NChen Gang <gang.chen@asianux.com>
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>

Use __free_reserved_page() to simplify the code in arch.

It used split_page() in consistent_alloc()/__dma_alloc_coherent()/dma_alloc_coherent(),
so page->_count == 1, and we can free it safely.

__free_reserved_page()
	ClearPageReserved()
	init_page_count()  // it won't change the value
	__free_page()
Signed-off-by: NXishi Qiu <qiuxishi@huawei.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Kick interrupts trigger the LWK (low level kick) signal, usually handled
by the __TBIDoStdLWK() function which is the only handler inherited from
the bootloader. The LWK signal is converted either to a SWK (plain
software kick) or a SWS (software kick with an attached message).

Linux has kick_handler() to handle SWK and call registered kick handlers
(IPIs and inter-thread comms), but SWS is as far as I'm aware unused
with Linux.

Therefore remove that abstraction and have Linux handle LWK directly.
This will reduce kick latency slightly, and reduce our dependence on the
bootloader, which makes it easier to directly boot a kernel in QEMU
(particularly for SMP).
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>

Move setup_machine_fdt out of prom.h and into asm/setup.h in preparation
to remove prom.h.
Signed-off-by: NRob Herring <rob.herring@calxeda.com>
Acked-by: NGrant Likely <grant.likely@linaro.org>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-metag@vger.kernel.org

Convert metag to use the common of_flat_dt_get_machine_name function.
Signed-off-by: NRob Herring <rob.herring@calxeda.com>
[james.hogan: fix missing arch_get_next_mach and const mismatch]
Reported-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>

Convert metag to use new early_init_dt_scan function.
Signed-off-by: NRob Herring <rob.herring@calxeda.com>
Cc: James Hogan <james.hogan@imgtec.com>

Use the common unflatten_and_copy_device_tree to copy the built-in FDT
out of init section.
Signed-off-by: NRob Herring <rob.herring@calxeda.com>
Cc: James Hogan <james.hogan@imgtec.com>

All arch overriden implementations of do_softirq() share the following
common code: disable irqs (to avoid races with the pending check),
check if there are softirqs pending, then execute __do_softirq() on
a specific stack.

Consolidate the common parts such that archs only worry about the
stack switch.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>

The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
are flagged as __cpuinit  -- so if we remove the __cpuinit from
arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
content into no-ops as early as possible, since that will get rid
of these warnings.  In any case, they are temporary and harmless.

This removes all the arch/metag uses of the __cpuinit macros from
all C files.  Currently metag does not have any __CPUINIT used in
assembly files.

[1] https://lkml.org/lkml/2013/5/20/589

Cc: James Hogan <james.hogan@imgtec.com>
Acked-by: NJames Hogan <james.hogan@imgtec.com>
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

Move EXPORT_SYMBOL(csum_partial) from lib/checksum.c into metag_ksyms.c
so that it doesn't get omitted by the static linker if it's not used by
any other statically linked code, which can result in undefined symbols
when building modules.

For example a randconfig caused the following error:
ERROR: "csum_partial" [fs/reiserfs/reiserfs.ko] undefined!
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>

The route_irq() function needs to preserve the irq mask by using the
_irqsave/irqrestore variants of raw spin lock functions instead of the
_irq variants. This is because it is called from __cpu_disable() (via
migrate_irqs()), which is called with IRQs disabled, so using the _irq
variants re-enables IRQs.

This appears to have been causing occasional hits of the
BUG_ON(!irqs_disabled()) in __irq_work_run() during CPU hotplug soak
testing:
  BUG: failure at kernel/irq_work.c:122/__irq_work_run()!
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>

kick_handler() doesn't have an irq_enter/exit pair, but it's used for
handling SMP IPIs which require work to be done in softirqs, which are
invoked from irq_exit() when the hard irq nest count reaches 0.

The scheduler_ipi() callback in the IPI handler calls irq_enter/exit
itself, but this is inside kick_handler()'s spin lock critical section,
so if an invoked softirq issues an IPI the kick_handler() will be
re-entered on the same CPU and will deadlock.

This is easily fixed by adding the missing irq_enter/exit to
kick_handler() so that the hard irq nest count doesn't reach 0 until
after the spin lock has been released.

Ideally the spin lock protected handler list will also be replaced by a
lockless RCU protected list since it is certainly mostly read. That can
be done in a later change though.
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>

Use a completion to block until a secondary CPU has started up, like ARM
do, instead of a loop of udelays.

On Meta, SMP is really SMT, with each "CPU" being a different hardware
thread on the same Meta processor core, so as well as being more
efficient and latency friendly, using a completion prevents the bogomips
of the secondary CPU from being drastically skewed every time by the
execution of the tight in-cache udelay loop on the other CPU.
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: N"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>

In secondary_start_kernel() interrupts should be enabled with
local_irq_enable() after the cpu is marked as online with
set_cpu_online(). Otherwise it's possible for a timer interrupt to
trigger a softirq, which if the cpu is marked as offline may have it's
affinity altered.
Reported-by: NKirill Tkhai <tkhai@yandex.ru>
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: N"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>