Commit 2965faa5e0 ("kexec: split kexec_load syscall from kexec core
code") introduced CONFIG_KEXEC_CORE so that CONFIG_KEXEC means whether
the kexec_load system call should be compiled-in and CONFIG_KEXEC_FILE
means whether the kexec_file_load system call should be compiled-in.
These options can be set independently from each other.
Since until now powerpc only supported kexec_load, CONFIG_KEXEC and
CONFIG_KEXEC_CORE were synonyms. That is not the case anymore, so we
need to make a distinction. Almost all places where CONFIG_KEXEC was
being used should be using CONFIG_KEXEC_CORE instead, since
kexec_file_load also needs that code compiled in.
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
From 80f23935ca ("powerpc: Convert cmp to cmpd in idle enter sequence"):
PowerPC's "cmp" instruction has four operands. Normally people write
"cmpw" or "cmpd" for the second cmp operand 0 or 1. But, frequently
people forget, and write "cmp" with just three operands.
With older binutils this is silently accepted as if this was "cmpw",
while often "cmpd" is wanted. With newer binutils GAS will complain
about this for 64-bit code. For 32-bit code it still silently assumes
"cmpw" is what is meant.
In this case, cmpwi is called for, so this is just a build fix for
new toolchains.
Cc: stable@vger.kernel.org # v3.0+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This adds a config option that can help exercise the case when
the kernel is not running at PAGE_OFFSET.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Pull kbuild updates from Michal Marek:
- EXPORT_SYMBOL for asm source by Al Viro.
This does bring a regression, because genksyms no longer generates
checksums for these symbols (CONFIG_MODVERSIONS). Nick Piggin is
working on a patch to fix this.
Plus, we are talking about functions like strcpy(), which rarely
change prototypes.
- Fixes for PPC fallout of the above by Stephen Rothwell and Nick
Piggin
- fixdep speedup by Alexey Dobriyan.
- preparatory work by Nick Piggin to allow architectures to build with
-ffunction-sections, -fdata-sections and --gc-sections
- CONFIG_THIN_ARCHIVES support by Stephen Rothwell
- fix for filenames with colons in the initramfs source by me.
* 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild: (22 commits)
initramfs: Escape colons in depfile
ppc: there is no clear_pages to export
powerpc/64: whitelist unresolved modversions CRCs
kbuild: -ffunction-sections fix for archs with conflicting sections
kbuild: add arch specific post-link Makefile
kbuild: allow archs to select link dead code/data elimination
kbuild: allow architectures to use thin archives instead of ld -r
kbuild: Regenerate genksyms lexer
kbuild: genksyms fix for typeof handling
fixdep: faster CONFIG_ search
ia64: move exports to definitions
sparc32: debride memcpy.S a bit
[sparc] unify 32bit and 64bit string.h
sparc: move exports to definitions
ppc: move exports to definitions
arm: move exports to definitions
s390: move exports to definitions
m68k: move exports to definitions
alpha: move exports to actual definitions
x86: move exports to actual definitions
...
Use assembler sections of fixed size and location to arrange the 64-bit
Book3S exception vector code (64-bit Book3E also uses it in head_64.S
for 0x0..0x100).
This allows better flexibility in arranging exception code and hiding
unimportant details behind macros.
Gas sections can be a bit painful to use this way, mainly because the
assembler does not know where they will be finally linked. Taking
absolute addresses requires a bit of trickery for example, but it can
be hidden behind macros for the most part.
Generated code is mostly the same except locations, offsets, alignments.
The "+ 0x2" is only required for the trap number / kvm exit number,
which gets loaded as a constant into a register.
Previously, code also used + 0x2 for label names, but we changed to
using "H" to distinguish HV case for that. Remove the last vestiges
of that.
__after_prom_start is taking absolute address of a label in another
fixed section. Newer toolchains seemed to compile this okay, but older
ones do not. FIXED_SYMBOL_ABS_ADDR is more foolproof, it just takes an
additional line to define.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
With a subsequent patch to put text into different sections,
(_end - _stext) can no longer be computed at link time to determine
the end of the copy. Instead, calculate it at runtime with
(copy_to_here - _stext) + (_end - copy_to_here).
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We're approaching 20 locations where we need to check for ELF ABI v2.
That's fine, except the logic is a bit awkward, because we have to check
that _CALL_ELF is defined and then what its value is.
So check it once in asm/types.h and define PPC64_ELF_ABI_v2 when ELF ABI
v2 is detected.
We also have a few places where what we're really trying to check is
that we are using the 64-bit v1 ABI, ie. function descriptors. So also
add a #define for that, which simplifies several checks.
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
With 4K page size radix config our level 1 page table size is 64K and it
should be naturally aligned.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This preserves the ability to build using older binutils (reportedly <=
2.22).
Fixes: 6becef7ea0 ("powerpc/mpc85xx: Add CPU hotplug support for E6500")
Signed-off-by: Scott Wood <oss@buserror.net>
Cc: chenhui.zhao@freescale.com
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Support Freescale E6500 core-based platforms, like t4240.
Support disabling/enabling individual CPU thread dynamically.
Signed-off-by: Chenhui Zhao <chenhui.zhao@freescale.com>
There is a RCPM (Run Control/Power Management) in Freescale QorIQ
series processors. The device performs tasks associated with device
run control and power management.
The driver implements some features: mask/unmask irq, enter/exit low
power states, freeze time base, etc.
Signed-off-by: Chenhui Zhao <chenhui.zhao@freescale.com>
Signed-off-by: Tang Yuantian <Yuantian.Tang@freescale.com>
[scottwood: remove __KERNEL__ ifdef]
Signed-off-by: Scott Wood <oss@buserror.net>
book3e is different with book3s since 3s includes the exception
vectors code in head_64.S as it relies on absolute addressing
which is only possible within this compilation unit. So we have
to get that label address with got.
And when boot a relocated kernel, we should reset ipvr properly again
after .relocate.
Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
[scottwood: cleanup and ifdef removal]
Signed-off-by: Scott Wood <scottwood@freescale.com>
Convert r4/r5, not r6, to a virtual address when calling
copy_and_flush. Otherwise, r3 is already virtual, and copy_to_flush
tries to access r3+r6, PAGE_OFFSET gets added twice.
This isn't normally seen because on book3e we normally enter with
the kernel at zero and thus skip copy_to_flush -- but it will be
needed for kexec support.
Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
[scottwood: split patch and rewrote changelog]
Signed-off-by: Scott Wood <scottwood@freescale.com>
Scott writes:
Highlights include e6500 hardware threading support, an e6500 TLB erratum
workaround, corenet error reporting, support for a new board, and some
minor fixes.
The general idea is that each core will release all of its
threads into the secondary thread startup code, which will
eventually wait in the secondary core holding area, for the
appropriate bit in the PACA to be set. The kick_cpu function
pointer will set that bit in the PACA, and thus "release"
the core/thread to boot. We also need to do a few things that
U-Boot normally does for CPUs (like enable branch prediction).
Signed-off-by: Andy Fleming <afleming@freescale.com>
[scottwood@freescale.com: various changes, including only enabling
threads if Linux wants to kick them]
Signed-off-by: Scott Wood <scottwood@freescale.com>
Old cpus didn't have a Segment Lookaside Buffer (SLB), instead they had
a Segment Table (STAB). Now that we've dropped support for those cpus,
we can remove the STAB support entirely.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
There is no need to put a function descriptor in
__secondary_hold_spinloop. Use ppc_function_entry to get the
instruction address and put it in __secondary_hold_spinloop instead.
Also fix an issue where we assumed cur_cpu_spec held a function
descriptor.
Signed-off-by: Anton Blanchard <anton@samba.org>
To establish addressability quickly, ABIv2 requires the target
address of the function being called to be in r12. Fix a number of
places in assembly code that we do indirect function calls.
We need to avoid function descriptors on ABIv2 too.
Signed-off-by: Anton Blanchard <anton@samba.org>
We have a number of places where we load the text address of a local
function and indirectly branch to it in assembly. Since it is an
indirect branch binutils will not know to use the function text
address, so that trick wont work.
There is no need for these functions to have a function descriptor
so we can replace it with a label and remove the dot symbol.
Signed-off-by: Anton Blanchard <anton@samba.org>
binutils is smart enough to know that a branch to a function
descriptor is actually a branch to the functions text address.
Alan tells me that binutils has been doing this for 9 years.
Signed-off-by: Anton Blanchard <anton@samba.org>
None of these files are actually using any __init type directives
and hence don't need to include <linux/init.h>. Most are just a
left over from __devinit and __cpuinit removal, or simply due to
code getting copied from one driver to the next.
The one instance where we add an include for init.h covers off
a case where that file was implicitly getting it from another
header which itself didn't need it.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Commit 5c0484e25e ('powerpc: Endian safe trampoline') resulted in
losing proper alignment of the spinlock variables used when booting
secondary CPUs, causing some quite odd issues with failing to boot on
PA Semi-based systems.
This showed itself on ppc64_defconfig, but not on pasemi_defconfig,
so it had gone unnoticed when I initially tested the LE patch set.
Fix is to add explicit alignment instead of relying on good luck. :)
[ It appears that there is a different issue with PA Semi systems
however this fix is definitely correct so applying anyway -- BenH
]
Fixes: 5c0484e25e ('powerpc: Endian safe trampoline')
Reported-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=67811
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
p_end is an 8 byte value embedded in the text section. This means it
is only 4 byte aligned when it should be 8 byte aligned. Fix this
by adding an explicit alignment.
This fixes an issue where POWER7 little endian builds with
CONFIG_RELOCATABLE=y fail to boot.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Create a trampoline that works in either endian and flips to
the expected endian. Use it for primary and secondary thread
entry as well as RTAS and OF call return.
Credit for finding the magic instruction goes to Paul Mackerras
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
p_toc is an 8 byte relative offset to the TOC that we place in the
text section. This means it is only 4 byte aligned where it should
be 8 byte aligned. Add an explicit alignment.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
In __after_prom_start we copy the kernel down to zero in two calls to
copy_and_flush. After the first call (copy from 0 to copy_to_here:)
we jump to the newly copied code soon after.
Unfortunately there's no isync between the copy of this code and the
jump to it. Hence it's possible that stale instructions could still be
in the icache or pipeline before we branch to it.
We've seen this on real machines and it's results in no console output
after:
calling quiesce...
returning from prom_init
The below adds an isync to ensure that the copy and flushing has
completed before any branching to the new instructions occurs.
Signed-off-by: Michael Neuling <mikey@neuling.org>
CC: <stable@vger.kernel.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Motivation:
IBM Blue Gene/Q comes with some very strange firmware that I'm trying to get out
of using in the kernel. So instead I spin all the threads in the boot wrapper
(using the firmware) and have them enter the kexec stub, pre-translated at the
virtual "linear" address, never touching firmware again.
This works strategy works wonderfully, but I need the following patch in the
kexec stub. I believe it should not effect Book3S and Book3E does not appear
to be here yet so I'd love to get any criticisms up front.
This patch adds two items:
1) Book3e requires that GPR4 survive the "hold" process, so we make
sure that happens.
2) Book3e has no real mode, and the hold code exploits this. Since
these processors ares always translated, we arrange for the kexeced
threads to enter the hold code using the normal kernel linear mapping.
Signed-off-by: Jimi Xenidis <jimix@pobox.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Finally remove the two level TOC and build with -mcmodel=medium.
Unfortunately we can't build modules with -mcmodel=medium due to
the tricks the kernel module loader plays with percpu data:
# -mcmodel=medium breaks modules because it uses 32bit offsets from
# the TOC pointer to create pointers where possible. Pointers into the
# percpu data area are created by this method.
#
# The kernel module loader relocates the percpu data section from the
# original location (starting with 0xd...) to somewhere in the base
# kernel percpu data space (starting with 0xc...). We need a full
# 64bit relocation for this to work, hence -mcmodel=large.
On older kernels we fall back to the two level TOC (-mminimal-toc)
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
POWER8/v2.07 allows exceptions to be taken with the MMU still on.
A new set of exception vectors is added at 0xc000_0000_0000_4xxx. When the HW
takes us here, MSR IR/DR will be set already and we no longer need a costly
RFID to turn the MMU back on again.
The original 0x0 based exception vectors remain for when the HW can't leave the
MMU on. Examples of this are when we can't trust the current MMU mappings,
like when we are changing from guest to hypervisor (HV 0 -> 1) or when the MMU
was off already. In these cases the HW will take us to the original 0x0 based
exception vectors with the MMU off as before.
This uses the new macros added previously too implement these new execption
vectors at 0xc000_0000_0000_4xxx. We exit these exception vectors using
mflr/blr (rather than mtspr SSR0/RFID), since we don't need the costly MMU
switch anymore.
This moves the __end_interrupts marker down past these new 0x4000 vectors since
they will need to be copied down to 0x0 when the kernel is not at 0x0.
Signed-off-by: Matt Evans <matt@ozlabs.org>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
If we build a kernel with CONFIG_RELOCATABLE=y CONFIG_CRASH_DUMP=n,
the kernel fails when we run at a non zero offset. It turns out
we were incorrectly wrapping some of the relocatable kernel code
with CONFIG_CRASH_DUMP.
Signed-off-by: Anton Blanchard <anton@samba.org>
Cc: <stable@kernel.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
OPAL provides the firmware base/entry in registers at boot time
for debugging purposes. We had a bug in the code trying to stash
these into the appropriate kernel globals (a line of code was
probably dropped by accident back when this was merged)
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The current implementation of lazy interrupts handling has some
issues that this tries to address.
We don't do the various workarounds we need to do when re-enabling
interrupts in some cases such as when returning from an interrupt
and thus we may still lose or get delayed decrementer or doorbell
interrupts.
The current scheme also makes it much harder to handle the external
"edge" interrupts provided by some BookE processors when using the
EPR facility (External Proxy) and the Freescale Hypervisor.
Additionally, we tend to keep interrupts hard disabled in a number
of cases, such as decrementer interrupts, external interrupts, or
when a masked decrementer interrupt is pending. This is sub-optimal.
This is an attempt at fixing it all in one go by reworking the way
we do the lazy interrupt disabling from the ground up.
The base idea is to replace the "hard_enabled" field with a
"irq_happened" field in which we store a bit mask of what interrupt
occurred while soft-disabled.
When re-enabling, either via arch_local_irq_restore() or when returning
from an interrupt, we can now decide what to do by testing bits in that
field.
We then implement replaying of the missed interrupts either by
re-using the existing exception frame (in exception exit case) or via
the creation of a new one from an assembly trampoline (in the
arch_local_irq_enable case).
This removes the need to play with the decrementer to try to create
fake interrupts, among others.
In addition, this adds a few refinements:
- We no longer hard disable decrementer interrupts that occur
while soft-disabled. We now simply bump the decrementer back to max
(on BookS) or leave it stopped (on BookE) and continue with hard interrupts
enabled, which means that we'll potentially get better sample quality from
performance monitor interrupts.
- Timer, decrementer and doorbell interrupts now hard-enable
shortly after removing the source of the interrupt, which means
they no longer run entirely hard disabled. Again, this will improve
perf sample quality.
- On Book3E 64-bit, we now make the performance monitor interrupt
act as an NMI like Book3S (the necessary C code for that to work
appear to already be present in the FSL perf code, notably calling
nmi_enter instead of irq_enter). (This also fixes a bug where BookE
perfmon interrupts could clobber r14 ... oops)
- We could make "masked" decrementer interrupts act as NMIs when doing
timer-based perf sampling to improve the sample quality.
Signed-off-by-yet: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
v2:
- Add hard-enable to decrementer, timer and doorbells
- Fix CR clobber in masked irq handling on BookE
- Make embedded perf interrupt act as an NMI
- Add a PACA_HAPPENED_EE_EDGE for use by FSL if they want
to retrigger an interrupt without preventing hard-enable
v3:
- Fix or vs. ori bug on Book3E
- Fix enabling of interrupts for some exceptions on Book3E
v4:
- Fix resend of doorbells on return from interrupt on Book3E
v5:
- Rebased on top of my latest series, which involves some significant
rework of some aspects of the patch.
v6:
- 32-bit compile fix
- more compile fixes with various .config combos
- factor out the asm code to soft-disable interrupts
- remove the C wrapper around preempt_schedule_irq
v7:
- Fix a bug with hard irq state tracking on native power7
This removes the various bits of assembly in the kernel entry,
exception handling and SLB management code that were specific
to running under the legacy iSeries hypervisor which is no
longer supported.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This adds a udbg and an hvc console backend for supporting a console
using the OPAL console interfaces.
On OPAL v1 we have hvc0 mapped to whatever console the system was
configured for (network or hvsi serial port) via the service
processor.
On OPAL v2 we have hvcN mapped to the Nth console provided by OPAL
which generally corresponds to:
hvc0 : network console (raw protocol)
hvc1 : serial port S1 (hvsi)
hvc2 : serial port S2 (hvsi)
Note: At this point, early debug console only works with OPAL v1
and shouldn't be enabled in a normal kernel.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
On machines supporting the OPAL firmware version 1, the system
is initially booted under pHyp. We then use a special hypercall
to verify if OPAL is available and if it is, we then trigger
a "takeover" which disables pHyp and loads the OPAL runtime
firmware, giving control to the kernel in hypervisor mode.
This patch add the necessary code to detect that the OPAL takeover
capability is present when running under PowerVM (aka pHyp) and
perform said takeover to get hypervisor control of the processor.
To perform the takeover, we must first use RTAS (within Open
Firmware runtime environment) to start all processors & threads,
in order to give control to OPAL on all of them. We then call
the takeover hypercall on everybody, OPAL will re-enter the kernel
main entry point passing it a flat device-tree.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
With OPAL, r8 and r9 will be used to pass the OPAL base and entry
for debugging purposes (those informations are also in the
device-tree). We don't want to clobber those registers that
early.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
smp_release_cpus() waits for all cpus (including the bootcpu) due to an
off-by-one count on boot_cpu_count (which is all CPUs). This patch replaces
that with spinning_secondaries (which is all secondary CPUs).
Signed-off-by: Matt Evans <matt@ozlabs.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Starting with 1426d5a3bd (powerpc:
Dynamically allocate pacas) we free the memory for pacas beyond
cpu_possible, but we failed to update the loop the secondary cpus use
to find their paca. If the system has running cpu threads for which
the kernel did not allocate a paca for they will search the memory that
was freed. For instance this could happen when the device tree for
a kdump kernel was not updated after a cpu hotplug, or the kernel is
running with more cpus than the kernel was configured.
Since c1854e0072 (powerpc: Set nr_cpu_ids
early and use it to free PACAs) we set nr_cpu_ids before telling the
cpus to advance, so use that to limit the search.
We can't reference nr_cpu_ids without CONFIG_SMP because it is defined
as 1 instead of a memory location, but any extra threads should be sent
to kexec_wait in that case anyways, so make that explicit and remove
the search loop for UP.
Note to stable: The fix also requires
c1854e0072 (powerpc: Set
nr_cpu_ids early and use it to free PACAs) to function. Also
9d07bc841c (Properly handshake CPUs going
out of boot spin loop) affects the second chunk, specifically the branch
target was 3b before and is 4b after that patch, and there was a blank
line before the #ifdef CONFIG_SMP that was removed
Cc: <stable@kernel.org> # .34.x: c1854e0072 powerpc: Set nr_cpu_ids early
Cc: <stable@kernel.org> # .34.x
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Use the new MSR_64BIT in a few places. Some of these are already ifdef'ed
for BOOKE vs BOOKS, but it's still clearer, MSR_SF does not immediately
parse as "MSR bit for 64bit".
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We need to do that to guarantee they see any code change done by
dynamic patching during boot.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We need to wait a bit for them to have done their CPU setup
or we might end up with translation and EE on with different
LPCR values between threads
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We do it before we loop on the PACA start flag. This way, we get a
chance to set critical SPRs on all CPUs before Linux tries to start
them up, which avoids problems when changing some bits such as LPCR
bits that need to be identical on all threads of a core or similar
things like that. Ideally, some of that should also be done before
the MMU is enabled, but that's a separate issue which would require
moving some of the SMP startup code earlier, let's not get there
for now, it works with that change alone.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
When running in Hypervisor mode (arch 2.06 or later), we store the PACA
in HSPRG0 instead of SPRG1. The architecture specifies that SPRGs may be
lost during a "nap" power management operation (though they aren't
currently on POWER7) and this enables use of SPRG1 by KVM guests.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The current code soft-disables, and then goes to NAP mode which
turns interrupts on. That means that if an interrupt occurs, we
will hit the masked interrupt code path which isn't what we want,
as it will return with EE off, which will either get us out of
NAP mode, or fail to enter it (according to spec).
Instead, let's just rely on the fact that it is safe to take
decrementer interrupts on an offline CPU and leave interrupts
enabled. We can also get rid of the special case in asm for
power4_cpu_offline_powersave() and just use power4_idle().
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
