Nothing stops a process from hotplugging in a CPU concurrently
with a sys_reboot() call. In such a situation we could have
ipi_cpu_stop() mark a cpu as 'offline' and _cpu_up() ignore the
fact that the CPU is not really offline and call the
CPU_UP_PREPARE notifier. When this happens stop_machine code will
complain that the cpu thread already exists and BUG_ON().
CPU0 CPU1
sys_reboot()
kernel_restart()
machine_restart()
machine_shutdown()
smp_send_stop()
... ipi_cpu_stop()
set_cpu_online(1, false)
local_irq_disable()
while(1)
<PREEMPT>
cpu_up()
_cpu_up()
if (!cpu_online(1))
__cpu_notify(CPU_UP_PREPARE...)
cpu_stop_cpu_callback()
BUG_ON(stopper->thread)
This is easily reproducible by hotplugging in and out in a tight
loop while also rebooting.
Since the CPU is not really offline and hasn't gone through the
proper steps to be marked as such, let's mark the CPU as inactive.
This is just as easily testable as online and avoids any possibility
of _cpu_up() trying to bring the CPU back online when it never was
offline to begin with.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
(cherry picked from commit 4a734179d918a4ee42c5fd6d54220eb6dd671ff0)
Change-Id: Id751200d45b58f12bf7d31ae5a7bc2ddd42ef92a
Signed-off-by: Sudhir Sharma <sudsha@codeaurora.org>
While running hotplug tests I ran into this RCU splat
===============================
[ INFO: suspicious RCU usage. ]
3.4.0 #3275 Tainted: G W
-------------------------------
include/linux/rcupdate.h:729 rcu_read_lock() used illegally while idle!
other info that might help us debug this:
RCU used illegally from idle CPU!
rcu_scheduler_active = 1, debug_locks = 0
RCU used illegally from extended quiescent state!
4 locks held by swapper/2/0:
#0: ((cpu_died).wait.lock){......}, at: [<c00ab128>] complete+0x1c/0x5c
#1: (&p->pi_lock){-.-.-.}, at: [<c00b275c>] try_to_wake_up+0x2c/0x388
#2: (&rq->lock){-.-.-.}, at: [<c00b2860>] try_to_wake_up+0x130/0x388
#3: (rcu_read_lock){.+.+..}, at: [<c00abe5c>] cpuacct_charge+0x28/0x1f4
stack backtrace:
[<c001521c>] (unwind_backtrace+0x0/0x12c) from [<c00abec8>] (cpuacct_charge+0x94/0x1f4)
[<c00abec8>] (cpuacct_charge+0x94/0x1f4) from [<c00b395c>] (update_curr+0x24c/0x2c8)
[<c00b395c>] (update_curr+0x24c/0x2c8) from [<c00b59c4>] (enqueue_task_fair+0x50/0x194)
[<c00b59c4>] (enqueue_task_fair+0x50/0x194) from [<c00afea4>] (enqueue_task+0x30/0x34)
[<c00afea4>] (enqueue_task+0x30/0x34) from [<c00b0908>] (ttwu_activate+0x14/0x38)
[<c00b0908>] (ttwu_activate+0x14/0x38) from [<c00b28a8>] (try_to_wake_up+0x178/0x388)
[<c00b28a8>] (try_to_wake_up+0x178/0x388) from [<c00a82a0>] (__wake_up_common+0x34/0x78)
[<c00a82a0>] (__wake_up_common+0x34/0x78) from [<c00ab154>] (complete+0x48/0x5c)
[<c00ab154>] (complete+0x48/0x5c) from [<c07db7cc>] (cpu_die+0x2c/0x58)
[<c07db7cc>] (cpu_die+0x2c/0x58) from [<c000f954>] (cpu_idle+0x64/0xfc)
[<c000f954>] (cpu_idle+0x64/0xfc) from [<80208160>] (0x80208160)
When a cpu is marked offline during its idle thread it calls
cpu_die() during an RCU idle period. cpu_die() calls complete()
to notify the killing process that the cpu has died. complete()
calls into the scheduler code and eventually grabs an RCU read
lock in cpuacct_charge().
Mark complete() as RCU_NONIDLE so that RCU pays attention to this
CPU for the duration of the complete() function even though it's
in idle.
Change-Id: I548a278e595737390bbc2c97bddda06a0725ecbd
Suggested-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Fix NR_IPI to be 7 instead of 6 because both googly and core add
an IPI.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Conflicts:
arch/arm/Kconfig
arch/arm/common/Makefile
arch/arm/include/asm/hardware/cache-l2x0.h
arch/arm/mm/cache-l2x0.c
arch/arm/mm/mmu.c
include/linux/wakelock.h
kernel/power/Kconfig
kernel/power/Makefile
kernel/power/main.c
kernel/power/power.h
Add support for the A15 generic timer and clocksource.
As the timer generates interrupts on a different PPI depending
on the execution mode (normal or secure), it is possible to
register two different PPIs.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Conflicts:
[Integrate to the recent patch which has changes to
local timer registration mechanism.
This fixes the crash seen during hotplug operations
where after a secondary CPU is brought back online,
the clock event device setup was happening as part
of the online notification mechanism which was too
late. With this change in the local timer mechanims,
the clock event device is now setup as part of the
secondary CPU boot initialization making it available
early enough for use.
Update the board file with the appropriate changes in
the argument for timer registration.]
arch/arm/Kconfig
arch/arm/include/asm/arch_timer.h
arch/arm/kernel/arch_timer.c
arch/arm/kernel/smp.c
Change-Id: I0bc80097c145fb2aac2150db0c5dff3c5e215a58
Signed-off-by: Sathish Ambley <sambley@codeaurora.org>
(cherry picked from commit df590ccd9d8210cc3e059671efad06dab7e70d4c)
Change-Id: Iedac55e097b8d983c42799b98f2d11f7b1a95f04
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>
Hotplug occurs frequently enough on our targets that its messages are
clogging up the logs. There is no need for any messages to be printed
when hotplug is successful.
Change-Id: Icf213ab409ba428f39439f886cdf4c070a48bfbf
Signed-off-by: Jeff Ohlstein <johlstei@codeaurora.org>
(cherry picked from commit 4d0bd4217b4e451843dc21208036d25f9d2871f8)
Conflicts:
arch/arm/kernel/smp.c
Commit 'ad3b6993' converted ARM smp_cross_call() to take IPI number
as a parameter to handle more event than SGI and do_IPI was suppose
to recover SGI number. But the do_IPI doesn't consider it and it's
getting detected as 'Unknown IPI message 0x1' with ipi numbers are
moved to starts from 'IPI_TIMER=2"
There can be 16 different SGI but only SGI1 is used as IPI so
only that one is handled in do_IPI as IPI_CPU_START.
Added IPI_CPU_START because it wasn't used and thought it's
appropriate. Not sure whether its the right one.
Change-Id: I4dbe7c489d9611fbbb4036c15ac247659fde4119
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Russell King <rmk+kernel at arm.linux.org.uk>
[johlstei@codeaurora.org: fixed bounds check error]
Signed-off-by: Jeff Ohlstein <johlstei@codeaurora.org>
(cherry picked from commit 7f685e51169149a877cb3100670567fb03c969f5)
Commit 4e8ee7de22 (ARM: SMP: use
idmap_pgd for mapping MMU enable during secondary booting)
switched secondary boot to use idmap_pgd, which is initialized
during early_initcall, instead of a page table initialized during
__cpu_up. This causes idmap_pgd to contain the static mappings
but be missing all dynamic mappings.
If a console is registered that creates a dynamic mapping, the
printk in secondary_start_kernel will trigger a data abort on
the missing mapping before the exception handlers have been
initialized, leading to a hang. Initial boot is not affected
because no consoles have been registered, and resume is usually
not affected because the offending console is suspended.
Onlining a cpu with hotplug triggers the problem.
A workaround is to the printk in secondary_start_kernel until
after the page tables have been switched back to init_mm.
Cc: <stable@vger.kernel.org>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
When performing a kexec on an SMP system, the secondary cores are stopped
by calling machine_shutdown(), which in turn issues IPIs to offline the
other CPUs. Unfortunately, this isn't enough to reboot the cores into
a new kernel (since they are just executing a cpu_relax loop somewhere
in memory) so we make use of platform_cpu_kill, part of the CPU hotplug
implementation, to place the cores somewhere safe. This function expects
to be called on the killing CPU for each core that it takes out.
This patch moves the platform_cpu_kill callback out of the IPI handler
and into smp_send_stop, therefore ensuring that it executes on the
killing CPU rather than on the victim, matching what the hotplug code
requires.
Cc: stable@vger.kernel.org
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Based on a rough patch by frank.rowand@am.sony.com
Since ARM doesn't have an NMI (fiq's are not always available),
send an IPI to all other CPUs (current cpu prints the stack directly)
to capture a backtrace.
Change-Id: I8b163c8cec05d521b433ae133795865e8a33d4e2
Signed-off-by: Dima Zavin <dima@android.com>
Pull cpumask cleanups from Rusty Russell:
"(Somehow forgot to send this out; it's been sitting in linux-next, and
if you don't want it, it can sit there another cycle)"
I'm a sucker for things that actually delete lines of code.
Fix up trivial conflict in arch/arm/kernel/kprobes.c, where Rusty fixed
a user of &cpu_online_map to be cpu_online_mask, but that code got
deleted by commit b21d55e98a ("ARM: 7332/1: extract out code patch
function from kprobes").
* tag 'for-linus' of git://github.com/rustyrussell/linux:
cpumask: remove old cpu_*_map.
documentation: remove references to cpu_*_map.
drivers/cpufreq/db8500-cpufreq: remove references to cpu_*_map.
remove references to cpu_*_map in arch/
Pull more ARM updates from Russell King.
This got a fair number of conflicts with the <asm/system.h> split, but
also with some other sparse-irq and header file include cleanups. They
all looked pretty trivial, though.
* 'for-linus' of git://git.linaro.org/people/rmk/linux-arm: (59 commits)
ARM: fix Kconfig warning for HAVE_BPF_JIT
ARM: 7361/1: provide XIP_VIRT_ADDR for no-MMU builds
ARM: 7349/1: integrator: convert to sparse irqs
ARM: 7259/3: net: JIT compiler for packet filters
ARM: 7334/1: add jump label support
ARM: 7333/2: jump label: detect %c support for ARM
ARM: 7338/1: add support for early console output via semihosting
ARM: use set_current_blocked() and block_sigmask()
ARM: exec: remove redundant set_fs(USER_DS)
ARM: 7332/1: extract out code patch function from kprobes
ARM: 7331/1: extract out insn generation code from ftrace
ARM: 7330/1: ftrace: use canonical Thumb-2 wide instruction format
ARM: 7351/1: ftrace: remove useless memory checks
ARM: 7316/1: kexec: EOI active and mask all interrupts in kexec crash path
ARM: Versatile Express: add NO_IOPORT
ARM: get rid of asm/irq.h in asm/prom.h
ARM: 7319/1: Print debug info for SIGBUS in user faults
ARM: 7318/1: gic: refactor irq_start assignment
ARM: 7317/1: irq: avoid NULL check in for_each_irq_desc loop
ARM: 7315/1: perf: add support for the Cortex-A7 PMU
...
Pull "ARM: timer cleanup work" from Arnd Bergmann:
"These are split out from the generic soc and driver updates because
there was a lot of conflicting work by multiple people. Marc Zyngier
worked on simplifying the "localtimer" interfaces, and some of the
platforms are touching the same code as they move to device tree based
booting.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>"
* tag 'timer' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (61 commits)
ARM: tegra: select USB_ULPI if USB is selected
arm/tegra: pcie: fix return value of function
ARM: ux500: fix compilation after local timer rework
ARM: shmobile: remove additional __io() macro use
ARM: local timers: make the runtime registration interface mandatory
ARM: local timers: convert MSM to runtime registration interface
ARM: local timers: convert exynos to runtime registration interface
ARM: smp_twd: remove old local timer interface
ARM: imx6q: convert to twd_local_timer_register() interface
ARM: highbank: convert to twd_local_timer_register() interface
ARM: ux500: convert to twd_local_timer_register() interface
ARM: shmobile: convert to twd_local_timer_register() interface
ARM: tegra: convert to twd_local_timer_register() interface
ARM: plat-versatile: convert to twd_local_timer_register() interface
ARM: OMAP4: convert to twd_local_timer_register() interface
ARM: smp_twd: add device tree support
ARM: smp_twd: add runtime registration support
ARM: local timers: introduce a new registration interface
ARM: smp_twd: make local_timer_stop a symbol instead of a #define
ARM: mach-shmobile: default to no earlytimer
...
Rather than open-coding the jiffy-based wait, and polling for the
secondary CPU to come online, use a completion instead. This
removes the need to poll, instead we will be notified when the
secondary CPU has initialized.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Remove all traces of the compile-time local timer interface,
and make the runtime selection mandatory.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
In order to switch to a runtime selectable local timer,
add a registration interface that timer drivers can use to
register to the core.
local_timer_setup() and local_timer_stop() are made weak symbols
in order not to break existing setups.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Stepan found:
CPU0 CPUn
_cpu_up()
__cpu_up()
boostrap()
notify_cpu_starting()
set_cpu_online()
while (!cpu_active())
cpu_relax()
<PREEMPT-out>
smp_call_function(.wait=1)
/* we find cpu_online() is true */
arch_send_call_function_ipi_mask()
/* wait-forever-more */
<PREEMPT-in>
local_irq_enable()
cpu_notify(CPU_ONLINE)
sched_cpu_active()
set_cpu_active()
Now the purpose of cpu_active is mostly with bringing down a cpu, where
we mark it !active to avoid the load-balancer from moving tasks to it
while we tear down the cpu. This is required because we only update the
sched_domain tree after we brought the cpu-down. And this is needed so
that some tasks can still run while we bring it down, we just don't want
new tasks to appear.
On cpu-up however the sched_domain tree doesn't yet include the new cpu,
so its invisible to the load-balancer, regardless of the active state.
So instead of setting the active state after we boot the new cpu (and
consequently having to wait for it before enabling interrupts) set the
cpu active before we set it online and avoid the whole mess.
Reported-by: Stepan Moskovchenko <stepanm@codeaurora.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1323965362.18942.71.camel@twins
Signed-off-by: Ingo Molnar <mingo@elte.hu>
It turns out that the logical CPU mapping is useful even when !CONFIG_SMP
for manipulation of devices like interrupt and power controllers when
running a UP kernel on a CPU other than 0. This can happen when kexecing
a UP image from an SMP kernel.
In the future, multi-cluster systems running AMP configurations will
require something similar for mapping cluster IDs, so it makes sense to
decouple this logic in preparation for this support.
Acked-by: Yang Bai <hamo.by@gmail.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Reported-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
We can stall RCU processing on SMP platforms if a CPU sits in its idle
loop for a long time. This happens because we don't call irq_enter()
and irq_exit() around generic_smp_call_function_interrupt() and
friends. Add the necessary calls, and remove the one from within
ipi_timer(), so that they're all in a common place.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Sending IPI_CPU_STOP to a CPU causes it to execute a busy cpu_relax
loop forever. This makes it impossible to kexec successfully on an SMP
system since the secondary CPUs do not reset.
This patch adds a callback to platform_cpu_kill, defined when
CONFIG_HOTPLUG_CPU=y, from the ipi_cpu_stop handling code. This function
currently just returns 1 on all platforms that define it but allows them
to do something more sophisticated in the future.
Signed-off-by: Will Deacon <will.deacon@arm.com>
The ARM SMP booting code allocates a temporary set of page tables
containing an identity mapping of the kernel image and provides this
to secondary CPUs for initial booting.
In reality, we only need to include the __turn_mmu_on function in the
identity mapping since the rest of the kernel is executing from virtual
addresses after this point.
This patch adds __turn_mmu_on to the .idmap.text section, allowing the
SMP booting code to use the idmap_pgd directly and not have to populate
its own set of page table.
As a result of this patch, we can make the identity_mapping_add function
static (since it is only used within mm/idmap.c) and also remove the
identity_mapping_del function. The identity map population is moved to
an early initcall so that it is setup in time for secondary CPU bringup.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
When disabling and re-enabling the MMU, it is necessary to take out an
identity mapping for the code that manipulates the SCTLR in order to
avoid it disappearing from under our feet. This is useful when soft
rebooting and returning from CPU suspend.
This patch allocates a set of page tables during boot and populates them
with an identity mapping for the .idmap.text section. This means that
users of the identity map do not need to manage their own pgd and can
instead annotate their functions with __idmap or, in the case of assembly
code, place them in the correct section.
Acked-by: Dave Martin <dave.martin@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
rtmutex: Add missing rcu_read_unlock() in debug_rt_mutex_print_deadlock()
lockdep: Comment all warnings
lib: atomic64: Change the type of local lock to raw_spinlock_t
locking, lib/atomic64: Annotate atomic64_lock::lock as raw
locking, x86, iommu: Annotate qi->q_lock as raw
locking, x86, iommu: Annotate irq_2_ir_lock as raw
locking, x86, iommu: Annotate iommu->register_lock as raw
locking, dma, ipu: Annotate bank_lock as raw
locking, ARM: Annotate low level hw locks as raw
locking, drivers/dca: Annotate dca_lock as raw
locking, powerpc: Annotate uic->lock as raw
locking, x86: mce: Annotate cmci_discover_lock as raw
locking, ACPI: Annotate c3_lock as raw
locking, oprofile: Annotate oprofilefs lock as raw
locking, video: Annotate vga console lock as raw
locking, latencytop: Annotate latency_lock as raw
locking, timer_stats: Annotate table_lock as raw
locking, rwsem: Annotate inner lock as raw
locking, semaphores: Annotate inner lock as raw
locking, sched: Annotate thread_group_cputimer as raw
...
Fix up conflicts in kernel/posix-cpu-timers.c manually: making
cputimer->cputime a raw lock conflicted with the ABBA fix in commit
bcd5cff721 ("cputimer: Cure lock inversion").
The problem is related to the early enabling of interrupts and the
per cpu timer setup before the cpu is marked online. This doesn't
need to be done in order to call calibrate_delay().
calibrate_delay() monitors jiffies, which are updated from the CPU
which is waiting for the new CPU to set the online bit.
So simply calibrate_delay() can be called on the new CPU just from
the interrupt disabled region and move the local timer setup after
stored the cpu data and before enabling interrupts.
This solves both the cpu_online vs. cpu_active problem and the
affinity setting of the per cpu timers.
Signed-off-by: Thomas Gleinxer <tglx@linutronix.de>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch remove the hardcoded link between local timers and PPIs,
and convert the PPI users (TWD, MCT and MSM timers) to the new
*_percpu_irq interface. Also some collateral cleanup
(local_timer_ack() is gone, and the interrupt handler is strictly
private to each driver).
PPIs are now useable for more than just the local timers.
Additional testing by David Brown (msm8250 and msm8660) and
Shawn Guo (imx6q).
Cc: David Brown <davidb@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: David Brown <davidb@codeaurora.org>
Tested-by: David Brown <davidb@codeaurora.org>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
The definition of __exception_irq_entry for
CONFIG_FUNCTION_GRAPH_TRACER=y needs linux/ftrace.h, but this creates a
circular dependency with it's current home in asm/system.h. Create
asm/exception.h and update all current users.
v4: - rebase to rmk/for-next
v3: - remove redundant includes of linux/ftrace.h
v2: - document the usage restricitions of __exception*
Cc: Zoltan Devai <zdevai@gmail.com>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
In order to be able to handle localtimer directly from C code instead of
assembly code, introduce handle_local_timer(), which is modeled after
handle_IRQ().
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
In order to be able to handle IPI directly from C code instead of
assembly code, introduce handle_IPI(), which is modeled after handle_IRQ().
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
To allow booting Linux on a CPU with physical ID != 0, we need to
provide a mapping from the logical CPU number to the physical CPU
number.
This patch adds such a mapping and populates it during boot.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The affinity between ARM processors is defined in the MPIDR register.
We can identify which processors are in the same cluster,
and which ones have performance interdependency. We can define the
cpu topology of ARM platform, that is then used by sched_mc and sched_smt.
The default state of sched_mc and sched_smt config is disable.
When enabled, the behavior of the scheduler can be modified with
sched_mc_power_savings and sched_smt_power_savings sysfs interfaces.
Changes since v4 :
* Remove unnecessary parentheses and blank lines
Changes since v3 :
* Update the format of printk message
* Remove blank line
Changes since v2 :
* Update the commit message and some comments
Changes since v1 :
* Update the commit message
* Add read_cpuid_mpidr in arch/arm/include/asm/cputype.h
* Modify header of arch/arm/kernel/topology.c
* Modify tests and manipulation of MPIDR's bitfields
* Modify the place and dependancy of the config
* Modify Noop functions
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Annotate the low level hardware locks which must not be preempted.
In mainline this change documents the low level nature of
the lock - otherwise there's no functional difference. Lockdep
and Sparse checking will work as usual.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
If an ARM system has multiple cpus in the same socket and the
kernel is booted with maxcpus=1, secondary cpus are possible but
not present due to how platform_smp_prepare_cpus() is called.
Since most typical ARM processors don't actually support physical
hotplug, initialize the present map to be equal to the possible
map in generic ARM SMP code. Also, always call
platform_smp_prepare_cpus() as long as max_cpus is non-zero (0
means no SMP) to allow platform code to do any SMP setup.
After applying this patch it's possible to boot an ARM system
with maxcpus=1 on the command line and then hotplug in secondary
cpus via sysfs. This is more in line with how x86 does things.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: David Brown <davidb@codeaurora.org>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
Cc: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
When we bring a CPU online, we should wait for it to become active
before entering the idle thread, so we know that the scheduler and
thread migration is going to work.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch makes TTBR1 point to swapper_pg_dir so that global, kernel
mappings can be used exclusively on v6 and v7 cores where they are
needed.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Rather than having each platform class provide a mach/smp.h header for
smp_cross_call(), arrange for them to register the function with the
core ARM SMP code instead.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This function is only called by percpu_timer_setup() which is
also __cpuinit marked. Thus it's safe to mark this function as
__cpuinit as well.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
