If we try to perform a kexec when the machine is in ST (Single-Threaded) mode
(ppc64_cpu --smt=off), the kexec operation doesn't succeed properly, and we
get the following messages during boot:

[    0.089866] POWER8 performance monitor hardware support registered
[    0.089985] power8-pmu: PMAO restore workaround active.
[    5.095419] Processor 1 is stuck.
[   10.097933] Processor 2 is stuck.
[   15.100480] Processor 3 is stuck.
[   20.102982] Processor 4 is stuck.
[   25.105489] Processor 5 is stuck.
[   30.108005] Processor 6 is stuck.
[   35.110518] Processor 7 is stuck.
[   40.113369] Processor 9 is stuck.
[   45.115879] Processor 10 is stuck.
[   50.118389] Processor 11 is stuck.
[   55.120904] Processor 12 is stuck.
[   60.123425] Processor 13 is stuck.
[   65.125970] Processor 14 is stuck.
[   70.128495] Processor 15 is stuck.
[   75.131316] Processor 17 is stuck.

Note that only the sibling threads are stuck, while the primary threads (0, 8,
16 etc) boot just fine. Looking closer at the previous step of kexec, we observe
that kexec tries to wakeup (bring online) the sibling threads of all the cores,
before performing kexec:

[ 9464.131231] Starting new kernel
[ 9464.148507] kexec: Waking offline cpu 1.
[ 9464.148552] kexec: Waking offline cpu 2.
[ 9464.148600] kexec: Waking offline cpu 3.
[ 9464.148636] kexec: Waking offline cpu 4.
[ 9464.148671] kexec: Waking offline cpu 5.
[ 9464.148708] kexec: Waking offline cpu 6.
[ 9464.148743] kexec: Waking offline cpu 7.
[ 9464.148779] kexec: Waking offline cpu 9.
[ 9464.148815] kexec: Waking offline cpu 10.
[ 9464.148851] kexec: Waking offline cpu 11.
[ 9464.148887] kexec: Waking offline cpu 12.
[ 9464.148922] kexec: Waking offline cpu 13.
[ 9464.148958] kexec: Waking offline cpu 14.
[ 9464.148994] kexec: Waking offline cpu 15.
[ 9464.149030] kexec: Waking offline cpu 17.

Instrumenting this piece of code revealed that the cpu_up() operation actually
fails with -EBUSY. Thus, only the primary threads of all the cores are online
during kexec, and hence this is a sure-shot receipe for disaster, as explained
in commit e8e5c215 (powerpc/kexec: Fix orphaned offline CPUs across kexec),
as well as in the comment above wake_offline_cpus().

It turns out that cpu_up() was returning -EBUSY because the variable
'cpu_hotplug_disabled' was set to 1; and this disabling of CPU hotplug was done
by migrate_to_reboot_cpu() inside kernel_kexec().

Now, migrate_to_reboot_cpu() was originally written with the assumption that
any further code will not need to perform CPU hotplug, since we are anyway in
the reboot path. However, kexec is clearly not such a case, since we depend on
onlining CPUs, atleast on powerpc.

So re-enable cpu-hotplug after returning from migrate_to_reboot_cpu() in the
kexec path, to fix this regression in kexec on powerpc.

Also, wrap the cpu_up() in powerpc kexec code within a WARN_ON(), so that we
can catch such issues more easily in the future.

Fixes: c97102ba (kexec: migrate to reboot cpu)
Cc: stable@vger.kernel.org
Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

We expose a number of OF properties in the kexec and crash dump code
and these need to be big endian.

Cc: stable@vger.kernel.org # v3.13
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Correct reference to the location of the kexec_sequence() assembly helper.
There never was a kexec_stub.S in mainline.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

commit b3f271e8 (powerpc: POWER7 optimised memcpy using VMX and
enhanced prefetch) uses VMX when it is safe to do so (ie not in
interrupt). It also looks at the task struct to decide if we have to
save the current tasks' VMX state.

kexec calls memcpy() at a point where the task struct may have been
overwritten by the new kexec segments. If it has been overwritten
then when memcpy -> enable_altivec looks up current->thread.regs->msr
we get a cryptic oops or lockup.

I also notice we aren't initialising thread_info->cpu, which means
smp_processor_id is broken. Fix that too.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Cc: <stable@vger.kernel.org> # 3.6+
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Disable hard IRQ before kexec a new kernel image.
Not doing it can result in corrupted data in the memory segments
reserved for the new kernel.
Signed-off-by: NPhileas Fogg <phileas-fogg@mail.ru>
CC: <stable@vger.kernel.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Rename the prom_*_property routines of the generic OF code to of_*_property.
This brings them in line with the naming used by the rest of the OF code.
Signed-off-by: NNathan Fontenot <nfont@linux.vnet.ibm.com>
Acked-by: NGeoff Levand <geoff@infradead.org>
Acked-by: NRob Herring <rob.herring@calxeda.com>
Acked-by: NGrant Likely <grant.likely@secretlab.ca>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Use the more commonly used __noreturn instead of ATTRIB_NORETURN.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NJoe Perches <joe@perches.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Acked-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: NRalf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It's a very old and now unused prototype marking so just delete it.

Neaten panic pointer argument style to keep checkpatch quiet.
Signed-off-by: NJoe Perches <joe@perches.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Acked-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: NRalf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use for_each_node_by_type instead of open coding it.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

When CPU hotplug is used, some CPUs may be offline at the time a kexec is
performed.  The subsequent kernel may expect these CPUs to be already running,
and will declare them stuck.  On pseries, there's also a soft-offline (cede)
state that CPUs may be in; this can also cause problems as the kexeced kernel
may ask RTAS if they're online -- and RTAS would say they are.  The CPU will
either appear stuck, or will cause a crash as we replace its cede loop beneath
it.

This patch kicks each present offline CPU awake before the kexec, so that
none are forever lost to these assumptions in the subsequent kernel.

Now, the behaviour is that all available CPUs that were offlined are now
online & usable after the kexec.  This mimics the behaviour of a full reboot
(on which all CPUs will be restarted).
Signed-off-by: NMatt Evans <matt@ozlabs.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Tidies some typos, KERN_INFO-ise an info msg, and add a debug msg showing
when the final sequence starts.

Also adds a comment to kexec_prepare_cpus_wait() to make note of a possible
problem; the need for kexec to deal with CPUs that failed to originally start
up.
Signed-off-by: NMatt Evans <matt@ozlabs.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

With dynamic PACAs, the kexecing CPU's PACA won't lie within the kernel
static data and there is a chance that something may stomp it when preparing
to kexec.  This patch switches this final CPU to a static PACA just before
we pull the switch.
Signed-off-by: NMatt Evans <matt@ozlabs.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Implement perf-events based hw-breakpoint interfaces for PowerPC
64-bit server (Book III S) processors.  This allows access to a
given location to be used as an event that can be counted or
profiled by the perf_events subsystem.

This is done using the DABR (data breakpoint register), which can
also be used for process debugging via ptrace.  When perf_event
hw_breakpoint support is configured in, the perf_event subsystem
manages the DABR and arbitrates access to it, and ptrace then
creates a perf_event when it is requested to set a data breakpoint.

[Adopted suggestions from Paul Mackerras <paulus@samba.org> to
- emulate_step() all system-wide breakpoints and single-step only the
  per-task breakpoints
- perform arch-specific cleanup before unregistration through
  arch_unregister_hw_breakpoint()
]
Signed-off-by: NK.Prasad <prasad@linux.vnet.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

kexec_perpare_cpus_wait() iterates i through NR_CPUS to check
paca[i].kexec_state of each to make sure they have quiesced.
However now we have dynamic PACA allocation, paca[NR_CPUS] is not necessarily
valid and we overrun the array;  spurious "cpu is not possible, ignoring"
errors result.  This patch iterates for_each_online_cpu so stays
within the bounds of paca[] -- and every CPU is now 'possible'.
Signed-off-by: NMatt Evans <matt@ozlabs.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

In kexec_prepare_cpus, the primary CPU IPIs the secondary CPUs to
kexec_smp_down().  kexec_smp_down() calls kexec_smp_wait() which sets
the hw_cpu_id() to -1.  The primary does this while leaving IRQs on
which means the primary can take a timer interrupt which can lead to
the IPIing one of the secondary CPUs (say, for a scheduler re-balance)
but since the secondary CPU now has a hw_cpu_id = -1, we IPI CPU
-1... Kaboom!

We are hitting this case regularly on POWER7 machines.

There is also a second race, where the primary will tear down the MMU
mappings before knowing the secondaries have entered real mode.

Also, the secondaries are clearing out any pending IPIs before
guaranteeing that no more will be received.

This changes kexec_prepare_cpus() so that we turn off IRQs in the
primary CPU much earlier.  It adds a paca flag to say that the
secondaries have entered the kexec_smp_down() IPI and turned off IRQs,
rather than overloading hw_cpu_id with -1.  This new paca flag is
again used to in indicate when the secondaries has entered real mode.

It also ensures that all CPUs have their IRQs off before we clear out
any pending IPI requests (in kexec_cpu_down()) to ensure there are no
trailing IPIs left unacknowledged.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NTim Abbott <tabbott@ksplice.com>
Acked-by: NPaul Mundt <lethal@linux-sh.org>
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>

Refactor the setting of kdump OF properties, moving the common code
from machine_kexec_64.c to machine_kexec.c where it can be used on
both ppc64 and ppc32.  This will be needed for kdump to work on ppc32
platforms.
Signed-off-by: NDale Farnsworth <dale@farnsworth.org>
Signed-off-by: NAnton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Refactor the setting of kexec OF properties, moving the common code
from machine_kexec_64.c to machine_kexec.c where it can be used on
both ppc64 and ppc32.  This is needed for kexec to work on ppc32
platforms.
Signed-off-by: NDale Farnsworth <dale@farnsworth.org>
Signed-off-by: NAnton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Commit 54622f10 ("powerpc: Support for
relocatable kdump kernel") added a magic flag value in a register to
tell purgatory that it should be a panic kernel.  This part is wrong
and is reverted by this commit.

The kernel gets a list of memory blocks and a entry point from user space.
Its job is to copy the blocks into place and then branch to the designated
entry point (after turning "off" the mmu).

The user space tool inserts a trampoline, called purgatory, that runs
before the user supplied code.   Its job is to establish the entry
environment for the new kernel or other application based on the contents
of memory.  The purgatory code is compiled and embedded in the tool,
where it is later patched using the elf symbol table using elf symbols.

Since the tool knows it is creating a purgatory that will run after a
kernel crash, it should just patch purgatory (or the kernel directly)
if something needs to happen.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

This adds relocatable kernel support for kdump. With this one can
use the same regular kernel to capture the kdump. A signature (0xfeed1234)
is passed in r6 from panic code to the next kernel through kexec_sequence
and purgatory code. The signature is used to differentiate between
kdump kernel and non-kdump kernels.

The purgatory code compares the signature and sets the __kdump_flag in
head_64.S.  During the boot up, kernel code checks __kdump_flag and if it
is set, the kernel will behave as relocatable kdump kernel. This kernel
will boot at the address where it was loaded by kexec-tools ie. at the
address reserved through crashkernel boot parameter.

CONFIG_CRASH_DUMP depends on CONFIG_RELOCATABLE option to build kdump
kernel as relocatable. So the same kernel can be used as production and
kdump kernel.

This patch incorporates the changes suggested by Paul Mackerras to avoid
GOT use and to avoid two copies of the code.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NMohan Kumar M <mohan@in.ibm.com>
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

64 bit powerpc requires the kexec user space tools avoid overwriting
the static kernel image and translation hash table when choosing
where to put memory image data because it copies the data into place
using the kernels virtual memory system.  Kexec userspace determines
these and other areas blocked by reading properties the kernel adds,
but does not filter these properties when creating the device tree
for the next kernel.

When the second kernel tries to add its values for these properties,
the export via /proc/device-tree is hidden by the pre-existing but
stale values from the flat tree.  Kexec userspace reads the old
property, allocates the new kernel at the old kernel's end, and
gets rejected by the overlap check.

Search and remove these stale properties before adding the new values.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Today's linux-next build (powerpc ppc64_defconfig) failed like this:

arch/powerpc/mm/tlb_64.c: In function 'pgtable_free_now':
arch/powerpc/mm/tlb_64.c:66: error: too many arguments to function 'smp_call_function'
arch/powerpc/kernel/machine_kexec_64.c: In function 'kexec_prepare_cpus':
arch/powerpc/kernel/machine_kexec_64.c:175: error: too many arguments to function 'smp_call_function'
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Acked-by: NJens Axboe <jens.axboe@oracle.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: <linuxppc-dev@ozlabs.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Make a few things static in lparcfg.c
Make init and exit routines static in rtas_flash.c
Make things static in rtas_pci.c
Make some functions static in rtas.c
Make fops static in rtas-proc.c
Remove unneeded extern for do_gtod in smp.c
Make clocksource_init() static in time.c
Make last_tick_len and ticklen_to_xs static in time.c
Move the declaration of the pvr per-cpu into smp.h
Make kexec_smp_down() and kexec_stack static in machine_kexec_64.c
Don't return void in arch_teardown_msi_irqs() in msi.c
Move declaration of GregorianDay()into asm/time.h
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

To compile kexec on 32-bit we need a few more bits and pieces. Rather
than add empty definitions, we can make crash.c work on 32-bit, with
only a couple of kludges.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

We're missing a few functions for kexec to compile on 32-bit. There's
nothing really 64-bit specific about the 64-bit versions, so make them
generic rather than adding empty definitions for 32-bit.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Now that get_property() returns a void *, there's no need to cast its
return value. Also, treat the return value as const, so we can
constify get_property later.

powerpc core changes.
Signed-off-by: NJeremy Kerr <jk@ozlabs.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

There's no reason kexec_setup() needs to be called explicitly from
setup_system(), it can just be a regular initcall.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

This was missing a quilt ref.
Signed-off-by: NPaul Mackerras <paulus@samba.org>

We currently do mem= handling in three seperate places. And as benh pointed out
I wrote two of them. Now that we parse command line parameters earlier we can
clean this mess up.

Moving the parsing out of prom_init means the device tree might be allocated
above the memory limit. If that happens we'd have to move it. As it happens
we already have logic to do that for kdump, so just genericise it.

This also means we might have reserved regions above the memory limit, if we
do the bootmem allocator will blow up, so we have to modify
lmb_enforce_memory_limit() to truncate the reserves as well.

Tested on P5 LPAR, iSeries, F50, 44p. Tested moving device tree on P5 and
44p and F50.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

For kexec we need to know the size of the MMU hash table.

Currently we calculate the size once in the htab code, and then twice more in
the kexec code, once using htab_hash_mask and once using ppc64_pft_size.
On some machines the ppc64_pft_size calculation is broken because
ppc64_pft_size is not set.

So we need to fix the second calculation, but better still we should just
calculate the size once and use it everywhere else.

Tested on Power5 LPAR, Power4 non-LPAR and Power3.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Implementing the machine_crash_shutdown which will be called by
crash_kexec (called in case of a panic, sysrq etc.). Disable the
interrupts, shootdown cpus using debugger IPI and collect regs
for all CPUs.

elfcorehdr= specifies the location of elf core header stored by
the crashed kernel. This command line option will be passed by
the kexec-tools to capture kernel.

savemaxmem= specifies the actual memory size that the first kernel
has and this value will be used for dumping in the capture kernel.
This command line option will be passed by the kexec-tools to
capture kernel.
Signed-off-by: NHaren Myneni <haren@us.ibm.com>
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

This patch separates usage of KERNELBASE and PAGE_OFFSET. I haven't
looked at any of the PPC32 code, if we ever want to support Kdump on
PPC we'll have to do another audit, ditto for iSeries.

This patch makes PAGE_OFFSET the constant, it'll always be 0xC * 1
gazillion for 64-bit.

To get a physical address from a virtual one you subtract PAGE_OFFSET,
_not_ KERNELBASE.

KERNELBASE is the virtual address of the start of the kernel, it's
often the same as PAGE_OFFSET, but _might not be_.

If you want to know something's offset from the start of the kernel
you should subtract KERNELBASE.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

This patch merges, to some extent, the PPC32 and PPC64 kexec implementations.

We adopt the PPC32 approach of having ppc_md callbacks for the kexec functions.
The current PPC64 implementation becomes the "default" implementation for PPC64
which platforms can select if they need no special treatment.

I've added these default callbacks to pseries/maple/cell/powermac, this means
iSeries no longer supports kexec - but it never worked anyway.

I've renamed PPC32's machine_kexec_simple to default_machine_kexec, inline with
PPC64. Judging by the comments it might be better named machine_kexec_non_of,
or something, but at the moment it's the only implementation for PPC32 so it's
the "default".

Kexec requires machine_shutdown(), which is in machine_kexec.c on PPC32, but we
already have in setup-common.c on powerpc. All this does is call
ppc_md.nvram_sync, which only powermac implements, so instead make
machine_shutdown a ppc_md member and have it call core99_nvram_sync directly
on powermac.

I've also stuck relocate_kernel.S into misc_32.S for powerpc.

Built for ARCH=ppc, and 32 & 64 bit ARCH=powerpc, with KEXEC=y/n. Booted on
P5 LPAR and successfully kexec'ed.

Should apply on top of 493f25ef.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Also deletes files in arch/ppc64 that are no longer used now that
we don't compile with ARCH=ppc64 any more.
Signed-off-by: NPaul Mackerras <paulus@samba.org>

The userspace kexec-tools need to know the location of the htab on non-lpar
machines, as well as the end of the kernel. Export via the device tree.

NB. This patch has been updated to use "linux,x" property names. You may
need to update your kexec-tools to match.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

We currently have a ppc_md member called cpu_irq_down, which disables IRQs
for the cpu in question. The only caller of cpu_irq_down is the kexec code.

On pSeries we need to do more than just teardown IRQs at kexec time, so rename
the ppc_md member to kexec_cpu_down and expand it. The pSeries code needs to
know, and other platforms might too, whether we're doing a crash shutdown (ie.
panicking) or a regular kexec, so add a flag for that.

The pSeries implementation of kexec_cpu_down does an unregister VPA call, which
tells the Hypervisor to stop writing stuff into our pacas. Without this we can
get weird memory corruption bugs when we kexec, caused by the Hypervisor
writing into the first kernel's pacas which happens to be somewhere interesting
in the second kernel's memory.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Mostly this involves adding #include <asm/smp.h>, since that defines
things like boot_cpuid[_phys] and [gs]et_hard_smp_processor_id, which
are SMP-related but still needed on UP.  This incorporates fixes
posted by Olof Johansson and Heikki Lindholm.
Signed-off-by: NPaul Mackerras <paulus@samba.org>

There's no reason for smp_release_cpus() to be asm, and most people can make
more sense of C code. Add an extern declaration to smp.h and remove the custom
one in machine_kexec.c
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>