Debug interrupts can be taken during interrupt entry, since interrupt
entry does not automatically turn them off. The kernel will check
whether the faulting instruction is between [interrupt_base_book3e,
__end_interrupts], and if so clear MSR[DE] and return.
However, when the kernel is built with CONFIG_RELOCATABLE, it can't use
LOAD_REG_IMMEDIATE(r14,interrupt_base_book3e) and
LOAD_REG_IMMEDIATE(r15,__end_interrupts), as they ignore relocation.
Thus, if the kernel is actually running at a different address than it
was built at, the address comparison will fail, and the exception entry
code will hang at kernel_dbg_exc.
r2(toc) is also not usable here, as r2 still holds data from the
interrupted context, so LOAD_REG_ADDR() doesn't work either. So we use
the *name@got* to get the EV of two labels directly.
Test programs test.c shows as follows:
int main(int argc, char *argv[])
{
if (access("/proc/sys/kernel/perf_event_paranoid", F_OK) == -1)
printf("Kernel doesn't have perf_event support\n");
}
Steps to reproduce the bug, for example:
1) ./gdb ./test
2) (gdb) b access
3) (gdb) r
4) (gdb) s
Signed-off-by: Liu Hailong <liu.hailong6@zte.com.cn>
Signed-off-by: Jiang Xuexin <jiang.xuexin@zte.com.cn>
Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
Reviewed-by: Liu Song <liu.song11@zte.com.cn>
Reviewed-by: Huang Jian <huang.jian@zte.com.cn>
[scottwood: cleaned up commit message, and specified bad behavior
as a hang rather than an oops to correspond to mainline kernel behavior]
Fixes: 1cb6e06492 ("powerpc/book3e: support CONFIG_RELOCATABLE")
Cc: <stable@vger.kernel.org> # 4.4.x-
Signed-off-by: Scott Wood <oss@buserror.net>
This converts one that was missed by b1576fec7f ("powerpc: No need
to use dot symbols when branching to a function").
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This patch provides VIRT_CPU_ACCOUTING to PPC32 architecture.
PPC32 doesn't have the PACA structure, so we use the task_info
structure to store the accounting data.
In order to reuse on PPC32 the PPC64 functions, all u64 data has
been replaced by 'unsigned long' so that it is u32 on PPC32 and
u64 on PPC64
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
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>
Rename 'interrupt_end_book3e' to '__end_interrupts' so that the symbol
can be used by both book3s and book3e.
Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
[scottwood: edit changelog]
Signed-off-by: Scott Wood <scottwood@freescale.com>
In CoreNet systems it is not allowed to mix M and non-M mappings to the
same memory, and coherent DMA accesses are considered to be M mappings
for this purpose. Ignoring this has been observed to cause hard
lockups in non-SMP kernels on e6500.
Furthermore, e6500 implements the LRAT (logical to real address table)
which allows KVM guests to control the WIMGE bits. This means that
KVM cannot force the M bit on the way it usually does, so the guest had
better set it itself.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Book3E specification defines shared interrupt numbers for SPE and AltiVec
units. Still SPE is present in e200/e500v2 cores while AltiVec is present in
e6500 core. So we can currently decide at compile-time which unit to support
exclusively. As Alexander Graf suggested, this will improve code readability
especially in KVM.
Use distinct defines to identify SPE/AltiVec interrupt numbers, reverting
c58ce397 and 6b310fc5 patches that added common defines.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
__attribute__ ((unused))
WSP is the last user of CONFIG_PPC_A2, so we remove that as well.
Although CONFIG_PPC_ICSWX still exists, it's no longer selectable for
any Book3E platform, so we can remove the code in mmu-book3e.h that
depended on it.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
STD_EXCEPTION_COMMON, STD_EXCEPTION_COMMON_ASYNC and
MASKABLE_EXCEPTION branch to the handler, so we can remove
the explicit dot symbol and binutils will do the right thing.
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>
Add special state saving for critical and machine check exceptions.
Most of this code could be used to handle debug exceptions taken from
kernel space, but actually doing so is outside the scope of this patch.
The various critical and machine check exceptions now point to their
real handlers, rather than hanging the kernel.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Use the proper scratch SPRG and PACA region. Introduce level-specific
macros to simplify usage and avoid needing to do a bunch of token
pasting throughout EXCEPTION_COMMON().
Now that EXCEPTION_COMMON_DBG() is properly using the debug scratch
register, there's no more need for the caller to move the value to the
GEN scratch first.
Signed-off-by: Scott Wood <scottwood@freescale.com>
The ints parameter was used to optionally insert RECONCILE_IRQ_STATE
into EXCEPTION_COMMON. However, since it came at the end of
EXCEPTION_COMMON, there was no real benefit for it to be there as
opposed to being called separately by the caller of EXCEPTION_COMMON.
The ints parameter was causing some hassle when trying to add an extra
macro layer. Besides avoiding that, moving "ints" to the caller makes
the code simpler by:
- avoiding the asymmetry where INTS_RESTORE_HARD is called separately
by the individual exception, but INTS_DISABLE was not
- removing the no-op INTS_KEEP
- not having an unnecessary macro parameter
It also turned out to be necessary to delay the INTS_DISABLE
in the case of special level exceptions until after we saved the
old value of PACAIRQHAPPENED.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Previously SPRG3 was marked for use by both VDSO and critical
interrupts (though critical interrupts were not fully implemented).
In commit 8b64a9dfb0 ("powerpc/booke64:
Use SPRG0/3 scratch for bolted TLB miss & crit int"), Mihai Caraman
made an attempt to resolve this conflict by restoring the VDSO value
early in the critical interrupt, but this has some issues:
- It's incompatible with EXCEPTION_COMMON which restores r13 from the
by-then-overwritten scratch (this cost me some debugging time).
- It forces critical exceptions to be a special case handled
differently from even machine check and debug level exceptions.
- It didn't occur to me that it was possible to make this work at all
(by doing a final "ld r13, PACA_EXCRIT+EX_R13(r13)") until after
I made (most of) this patch. :-)
It might be worth investigating using a load rather than SPRG on return
from all exceptions (except TLB misses where the scratch never leaves
the SPRG) -- it could save a few cycles. Until then, let's stick with
SPRG for all exceptions.
Since we cannot use SPRG4-7 for scratch without corrupting the state of
a KVM guest, move VDSO to SPRG7 on book3e. Since neither SPRG4-7 nor
critical interrupts exist on book3s, SPRG3 is still used for VDSO
there.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Cc: Mihai Caraman <mihai.caraman@freescale.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: kvm-ppc@vger.kernel.org
altivec_unavailable was commented as 0xf20 but the code uses 0x200.
Note that 0xf20 is also used by ap_unavailable.
altivec_assist was commented as 0x1700 but the code uses 0x220.
critical_input was commented as 0x580 but the code uses 0x100.
machine_check was commented and implemented as 0x200, which conflicts
with altivec_assist (it only builds because MC_EXCEPTION_PROLOG is
commented out). Changed to the fixed IVOR value of 0x000.
Signed-off-by: Scott Wood <scottwood@freescale.com>
We need to store thread info to these exception thread info like something
we already did for PPC32.
Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>
On Freescale e6500 cores EPCR[DGTMI] controls whether guest supervisor
state can execute TLB management instructions. If EPCR[DGTMI]=0
tlbwe and tlbilx are allowed to execute normally in the guest state.
A hypervisor may choose to virtualize TLB1 and for this purpose it
may use IPROT to protect the entries for being invalidated by the
guest. However, because tlbwe and tlbilx execution in the guest state
are sharing the same bit, it is not possible to have a scenario where
tlbwe is allowed to be executed in guest state and tlbilx traps. When
guest TLB management instructions are allowed to be executed in guest
state the guest cannot use tlbilx to invalidate TLB1 guest entries.
Linux is using tlbilx in the boot code to invalidate the temporary
entries it creates when initializing the MMU. The patch is replacing
the usage of tlbilx in initialization code with tlbwe with VALID bit
cleared.
Linux is also using tlbilx in other contexts (like huge pages or
indirect entries) but removing the tlbilx from the initialization code
offers the possibility to have scenarios under hypervisor which are
not using huge pages or indirect entries.
Signed-off-by: Diana Craciun <Diana.Craciun@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>
LRAT (Logical to Real Address Translation) present in MMU v2 provides hardware
translation from a logical page number (LPN) to a real page number (RPN) when
tlbwe is executed by a guest or when a page table translation occurs from a
guest virtual address.
Add LRAT error exception handler to Booke3E 64-bit kernel and the basic KVM
handler to avoid build breakage. This is a prerequisite for KVM LRAT support
that will follow.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>
On Book3E some SPE/FP/AltiVec interrupts share the same number. Use
common defines to indentify these numbers.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>
The performance monitor interrupt is asynchronous, so we should check
if the current processor is in napping status in the handler of this
interrupt.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The SOFT_DISABLE_INTS seems an odd name for something that updates the
software state to be consistent with interrupts being hard disabled, so
rename SOFT_DISABLE_INTS with RECONCILE_IRQ_STATE to avoid this confusion.
Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
MSR_DE is not cleared on entry to the kernel, and we don't clear it
explicitly outside of debug code. If we have MSR_DE set in
prime_debug_regs(), and the new thread has events enabled in DBCR0
(e.g. ICMP is set in thread->dbsr0, even though it was cleared in the
real DBCR0 when the thread got scheduled out), we'll end up taking a
debug exception in the kernel when DBCR0 is loaded. DSRR0 will not
point to an exception vector, and the kernel ends up hanging at
kernel_dbg_exc. Fix this by always clearing MSR_DE when we load new
debug state.
Another observed source of kernel_dbg_exc hangs is with the branch
taken event. If this event is active, but we take a non-debug trap
(e.g. a TLB miss or an asynchronous interrupt) before the next branch.
We end up taking a branch-taken debug exception on the initial branch
instruction of the exception vector, but because the debug exception is
DBSR_BT rather than DBSR_IC we branch to kernel_dbg_exc before even
checking the DSRR0 address. Fix this by checking for DBSR_BT as well
as DBSR_IC, which is what 32-bit does and what the comments suggest was
intended in the 64-bit code as well.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The e6500 core adds support for AltiVec on a Book-E class processor.
Connect up all the various exception handling code and build config
mechanisms to allow user spaces apps to utilize AltiVec.
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
[PATCH 1/6] powerpc: Move branch instruction from ACCOUNT_CPU_USER_ENTRY to caller
The first instruction in ACCOUNT_CPU_USER_ENTRY is 'beq' which checks for
exceptions coming from kernel mode. PPR value will be saved immediately after
ACCOUNT_CPU_USER_ENTRY and is also for user level exceptions. So moved this
branch instruction in the caller code.
Signed-off-by: Haren Myneni <haren@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
For the 64 bit case separate out e5500 cpu_setup and cpu_restore functions.
The cpu_setup function (for the primary core) is passed the cpu_spec
pointer, which is not there in case of the cpu_restore function. Also, in
our case we will have to manipulate the CPU_FTR_EMB_HV flag on the primary
core.
Signed-off-by: Varun Sethi <Varun.Sethi@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Critical exception on 64-bit booke uses user-visible SPRG3 as scratch.
Restore VDSO information in SPRG3 on exception prolog.
Use a common sprg3 field in PACA for all powerpc64 architectures.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Embedded.Hypervisor category defines GSPRG0..3 physical registers for guests.
Avoid SPRG4-7 usage as scratch in host exception handlers, otherwise guest
SPRG4-7 registers will be clobbered.
For bolted TLB miss exception handlers, which is the version currently
supported by KVM, use SPRN_SPRG_GEN_SCRATCH aka SPRG0 instead of
SPRN_SPRG_TLB_SCRATCH aka SPRG6. Keep using TLB PACA slots to fit in one
64-byte cache line.
For critical exception handlers use SPRG3 instead of SPRG7. Provide a routine
to store and restore user-visible SPRGs. This will be subsequently used
to restore VDSO information in SPRG3. Add EX_R13 to paca slots to free up
SPRG3 and change the critical exception epilog to use it.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Refactor exception prolog to get rid of mfspr srr1 duplicate. This was
introduced by KVM integration, with DO_KVM macro logic expecting srr1 value
earlier in r11.
Reserve r11 to hold srr1's value also required at the end of the prolog and
free up r10 to serve as spare in addition macros.
For syscalls case this change does not add any performance penalty. For irq
soft-disabled case the change adds a store/load of conditional register value
to/from a paca slot. Paca slots fit in one 64-byte cache line so these
additional operations have little impact on performance.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Hook DO_KVM macro into 64-bit booke for KVM integration. Extend interrupt
handlers' parameter list with interrupt vector numbers to accomodate the macro.
Only the bolted version of tlb miss handers is addressed now.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Guest Doorbell interrupts use guest save and restore registers. Add a new
Guest Doorbell exception type to accommodate GSRR0/1 SPRs usage in exception
prolog and fix the exception handler.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Machine check exception handler was using a wrong prolog. Hypervisors like
KVM which are called early from the exception handler rely on the interrupt
source.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Some macros use RA where when RA=R0 the values is 0, so make this
the enforced mnemonic in the macro.
Idea suggested by Andreas Schwab.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
These macros are using integers where they could be using logical
names since they take registers.
We are going to enforce this soon, so fix these up now.
Signed-off-by: Michael Neuling <mikey@neuling.org>
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
We were using CR0.EQ after EXCEPTION_COMMON, hoping it still
contained whether we came from userspace or kernel space.
However, under some circumstances, EXCEPTION_COMMON will
call C code and clobber non-volatile registers, so we really
need to re-load the previous MSR from the stackframe and
re-test.
While there, invert the condition to make the fast path more
obvious and remove the BUG_OPCODE which was a debugging
leftover and call .ret_from_except as we should.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
If we get a floating point, altivec or vsx unavaible interrupt in
kernel, we trigger a kernel error. There is no point preserving
the interrupt state, in fact, that can even make debugging harder
as the processor state might change (we may even preempt) between
taking the exception and landing in a debugger.
So just make those 3 disable interrupts unconditionally.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
v2: On BookE only disable when hitting the kernel unavailable
path, otherwise it will fail to restore softe as
fast_exception_return doesn't do it.
We currently turn interrupts back to their previous state before
calling do_page_fault(). This can be annoying when debugging as
a bad fault will potentially have lost some processor state before
getting into the debugger.
We also end up calling some generic code with interrupts enabled
such as notify_page_fault() with interrupts enabled, which could
be unexpected.
This changes our code to behave more like other architectures,
and make the assembly entry code call into do_page_faults() with
interrupts disabled. They are conditionally re-enabled from
within do_page_fault() in the same spot x86 does it.
While there, add the might_sleep() test in the case of a successful
trylock of the mmap semaphore, again like x86.
Also fix a bug in the existing assembly where r12 (_MSR) could get
clobbered by C calls (the DTL accounting in the exception common
macro and DISABLE_INTS) in some cases.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
v2. Add the r12 clobber fix
Without this, we attempt to use doorbells for IPIs, and end up
branching to some bad address. Plus, even for the exceptions
we don't implement, it's good to handle it and get a message out.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Jack Miller <jack@codezen.org>
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Add a platform for the Wire Speed Processor, based on the PPC A2.
This includes code for the ICS & OPB interrupt controllers, as well
as a SCOM backend, and SCOM based cpu bringup.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Jack Miller <jack@codezen.org>
Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
When we set up the TLB for ourselves on Book3E, we need to flush out any
old mappings established by the firmware or bootloader. At present we
attempt this with a tlbilx to flush everything, but this will leave behind
any entries with the IPROT bit set.
There are several good reason firmware might establish mappings with IPROT,
and in fact ePAPR compliant firmwares are required to establish their
initial mapped area with IPROT.
This patch, therefore adds more complex code to scan through the TLB upon
entry and flush away any entries that are not our own.
Signed-off-by: Jack Miller <jack@codezen.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
An erratum on A2 can lead to the bolted entry we insert for the linear
mapping being evicted, to avoid that write the bolted entry to way 3.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We patch the TLB miss exception vectors to point to alternate
functions when using HW page table on BookE.
However, we were patching in a new branch in the first instruction
of the exception handler instead of the second one, thus overriding
the nop that is in the first instruction.
This cause problems when single stepping as we rely on that nop for
the single step to stop properly within the exception vector range
rather than on the target of the branch.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We use a similar technique to ppc32: We set a thread local flag
to indicate that we are about to enter or have entered the stop
state, and have fixup code in the async interrupt entry code that
reacts to this flag to make us return to a different location
(sets NIP to LINK in our case).
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
--
v2. Fix lockdep bug
Re-mask interrupts when coming back from idle
LiuHailong