POWER9 changes requirements and adds new instructions for
synchronization.
Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Change the doorbell callers to know about their msgsnd addressing,
rather than have them set a per-cpu target data tag at boot that gets
sent to the cause_ipi functions. The data is only used for doorbell IPI
functions, no other IPI types, so it makes sense to keep that detail
local to doorbell.

Have the platform code understand doorbell IPIs, rather than the
interrupt controller code understand them. Platform code can look at
capabilities it has available and decide which to use.
Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Add the bit definition and use it in facility_unavailable_exception() so we can
intelligently report the cause if we take a fault for SCV. This doesn't actually
enable SCV.
Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
[mpe: Drop whitespace changes to the existing entries, flush out change log]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

We have a #define for it, so use it.
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The current behaviour of the hash table dump assumes that memory is contiguous
and iterates from the start of memory to (start + size of memory). When memory
isn't physically contiguous, this doesn't work.

If memory exists at 0-5 GB and 6-10 GB then the current approach will check if
entries exist in the hash table from 0GB to 9GB. This patch changes the
behaviour to iterate over any holes up to the end of memory.

Fixes: 1515ab93 ("powerpc/mm: Dump hash table")
Signed-off-by: NRashmica Gupta <rashmica.g@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The current page table dumper scans the Linux page tables and coalesces mappings
with adjacent virtual addresses and similar PTE flags. This behaviour is
somewhat broken when you consider the IOREMAP space where entirely unrelated
mappings will appear to be virtually contiguous. This patch modifies the range
coalescing so that only ranges that are both physically and virtually contiguous
are combined. This patch also adds to the dump output the physical address at
the start of each range.

Fixes: 8eb07b18 ("powerpc/mm: Dump linux pagetables")
Signed-off-by: NOliver O'Halloran <oohall@gmail.com>
[mpe: Print the physicall address with 0x like the other addresses]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

On Book3s we have two PTE flags used to mark cache-inhibited mappings:
_PAGE_TOLERANT and _PAGE_NON_IDEMPOTENT. Currently the kernel page table dumper
only looks at the generic _PAGE_NO_CACHE which is defined to be _PAGE_TOLERANT.
This patch modifies the dumper so both flags are shown in the dump.

Fixes: 8eb07b18 ("powerpc/mm: Dump linux pagetables")
Signed-off-by: NOliver O'Halloran <oohall@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Currently sys_mmap() and sys_mmap2() (32-bit only), are not visible to the
syscall tracing machinery. This means users are not able to see the execution of
mmap() syscalls using the syscall tracer.

Fix that by using SYSCALL_DEFINE6 for sys_mmap() and sys_mmap2() so that the
meta-data associated with these syscalls is visible to the syscall tracer.

A side-effect of this change is that the return type has changed from unsigned
long to long. However this should have no effect, the only code in the kernel
which uses the result of these syscalls is in the syscall return path, which is
written in asm and treats the result as unsigned regardless.

Example output:
  cat-3399  [001] ....   196.542410: sys_mmap(addr: 7fff922a0000, len: 20000, prot: 3, flags: 812, fd: 3, offset: 1b0000)
  cat-3399  [001] ....   196.542443: sys_mmap -> 0x7fff922a0000
  cat-3399  [001] ....   196.542668: sys_munmap(addr: 7fff922c0000, len: 6d2c)
  cat-3399  [001] ....   196.542677: sys_munmap -> 0x0
Signed-off-by: NBalbir Singh <bsingharora@gmail.com>
[mpe: Massage change log, add detail on return type change]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Recently in commit f6eedbba ("powerpc/mm/hash: Increase VA range to 128TB"),
we increased H_PGD_INDEX_SIZE to 15 when we're building with 64K pages. This
makes it larger than RADIX_PGD_INDEX_SIZE (13), which means the logic to
calculate MAX_PGD_INDEX_SIZE in book3s/64/pgtable.h is wrong.

The end result is that the PGD (Page Global Directory, ie top level page table)
of the kernel (aka. swapper_pg_dir), is too small.

This generally doesn't lead to a crash, as we don't use the full range in normal
operation. However if we try to dump the kernel pagetables we can trigger a
crash because we walk off the end of the pgd into other memory and eventually
try to dereference something bogus:

  $ cat /sys/kernel/debug/kernel_pagetables
  Unable to handle kernel paging request for data at address 0xe8fece0000000000
  Faulting instruction address: 0xc000000000072314
  cpu 0xc: Vector: 380 (Data SLB Access) at [c0000000daa13890]
      pc: c000000000072314: ptdump_show+0x164/0x430
      lr: c000000000072550: ptdump_show+0x3a0/0x430
     dar: e802cf0000000000
  seq_read+0xf8/0x560
  full_proxy_read+0x84/0xc0
  __vfs_read+0x6c/0x1d0
  vfs_read+0xbc/0x1b0
  SyS_read+0x6c/0x110
  system_call+0x38/0xfc

The root cause is that MAX_PGD_INDEX_SIZE isn't actually computed to be
the max of H_PGD_INDEX_SIZE or RADIX_PGD_INDEX_SIZE. To fix that move
the calculation into asm-offsets.c where we can do it easily using
max().

Fixes: f6eedbba ("powerpc/mm/hash: Increase VA range to 128TB")
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

POWER9 DD1.0 hardware has a bug where the SPRs of a thread waking up
from stop 0,1,2 with ESL=1 can endup being misplaced in the core. Thus
the HSPRG0 of a thread waking up from can contain the paca pointer of
its sibling.

This patch implements a context recovery framework within threads of a
core, by provisioning space in paca_struct for saving every sibling
threads's paca pointers. Basically, we should be able to arrive at the
right paca pointer from any of the thread's existing paca pointer.

At bootup, during powernv idle-init, we save the paca address of every
CPU in each one its siblings paca_struct in the slot corresponding to
this CPU's index in the core.

On wakeup from a stop, the thread will determine its index in the core
from the TIR register and recover its PACA pointer by indexing into
the correct slot in the provisioned space in the current PACA.

Furthermore, ensure that the NVGPRs are restored from the stack on the
way out by setting the NAPSTATELOST in paca.

[Changelog written with inputs from svaidy@linux.vnet.ibm.com]
Signed-off-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com>
Reviewed-by: NNicholas Piggin <npiggin@gmail.com>
[mpe: Call it a bug]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Currently during idle-init on power9, if we don't find suitable stop
states in the device tree that can be used as the
default_stop/deepest_stop, we set stop0 (ESL=1,EC=1) as the default
stop state psscr to be used by power9_idle and deepest stop state
which is used by CPU-Hotplug.

However, if the platform firmware has not configured or enabled a stop
state, the kernel should not make any assumptions and fallback to a
default choice.

If the kernel uses a stop state that is not configured by the platform
firmware, it may lead to further failures which should be avoided.

In this patch, we modify the init code to ensure that the kernel uses
only the stop states exposed by the firmware through the device
tree. When a suitable default stop state isn't found, we disable
ppc_md.power_save for power9. Similarly, when a suitable
deepest_stop_state is not found in the device tree exported by the
firmware, fall back to the default busy-wait loop in the CPU-Hotplug
code.

[Changelog written with inputs from svaidy@linux.vnet.ibm.com]
Reviewed-by: NNicholas Piggin <npiggin@gmail.com>
Signed-off-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Currently, the powernv cpu-offline function assumes that platform idle
states such as stop on POWER9, winkle/sleep/nap on POWER8 are always
available. On POWER8, it picks nap as the default state if other deep
idle states like sleep/winkle are not available and enabled in the
platform.

On POWER9, nap is not available and all idle states are managed by
STOP instruction.  The parameters to the idle state are passed through
processor stop status control register (PSSCR).  Hence as such
executing STOP would take parameters from current PSSCR. We do not
want to make any assumptions in kernel on what STOP states and PSSCR
features are configured by the platform.

Ideally platform will configure a good set of stop states that can be
used in the kernel.  We would like to start with a clean slate, if the
platform choose to not configure any state or there is an error in
platform firmware that lead to no stop states being configured or
allowed to be requested.

This patch adds a fallback method for CPU-Hotplug that is similar to
snooze loop at idle where the threads are left to spin at low priority
and hence reduce the cycles consumed.

This is a safe fallback mechanism in the case when no stop state would
be requested if the platform firmware did not configure them most
likely due to an error condition.

Requesting a stop state when the platform has not configured them or
enabled them would lead to further error conditions which could be
difficult to debug.

[Changelog written with inputs from svaidy@linux.vnet.ibm.com]
Reviewed-by: NNicholas Piggin <npiggin@gmail.com>
Signed-off-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Move the piece of code in powernv/smp.c::pnv_smp_cpu_kill_self() which
transitions the CPU to the deepest available platform idle state to a
new function named pnv_cpu_offline() in powernv/idle.c. The rationale
behind this code movement is that the data required to determine the
deepest available platform state resides in powernv/idle.c.
Reviewed-by: NNicholas Piggin <npiggin@gmail.com>
Signed-off-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Add user space exported API definitions for 512KB, 1MB, 2MB, 8MB, 16MB,
1GB, 16GB non default huge page sizes to be used with mmap() system
call.
Signed-off-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>
[mpe: Reword the comment to emphasise that these are only needed to use
 the non-default huge page size, and updated the change log.]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Generic core VM already prints these information in the log
buffer, hence there is no need for a second print. This just
removes the second print from arch powerpc NUMA init path.

Before the patch:

  $ dmesg | grep "Initmem"

  numa: Initmem setup node 0 [mem 0x00000000-0xffffffff]
  numa: Initmem setup node 1 [mem 0x100000000-0x1ffffffff]
  numa: Initmem setup node 2 [mem 0x200000000-0x2ffffffff]
  numa: Initmem setup node 3 [mem 0x300000000-0x3ffffffff]
  numa: Initmem setup node 4 [mem 0x400000000-0x4ffffffff]
  numa: Initmem setup node 5 [mem 0x500000000-0x5ffffffff]
  numa: Initmem setup node 6 [mem 0x600000000-0x6ffffffff]
  numa: Initmem setup node 7 [mem 0x700000000-0x7ffffffff]
  Initmem setup node 0 [mem 0x0000000000000000-0x00000000ffffffff]
  Initmem setup node 1 [mem 0x0000000100000000-0x00000001ffffffff]
  Initmem setup node 2 [mem 0x0000000200000000-0x00000002ffffffff]
  Initmem setup node 3 [mem 0x0000000300000000-0x00000003ffffffff]
  Initmem setup node 4 [mem 0x0000000400000000-0x00000004ffffffff]
  Initmem setup node 5 [mem 0x0000000500000000-0x00000005ffffffff]
  Initmem setup node 6 [mem 0x0000000600000000-0x00000006ffffffff]
  Initmem setup node 7 [mem 0x0000000700000000-0x00000007ffffffff]

After the patch just the latter set is printed.
Signed-off-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Make sparsemem the default on all 64-bit Book3S platforms. It already is
for pseries and ps3, and we need to enable it for powernv because on
POWER9 memory between chips is discontiguous.

For the other platforms sparsemem should work fine, though it might add
a small amount of overhead. We can always force FLATMEM in the
defconfigs if necessary.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

setup_initial_memory_limit() is called from early_init_devtree(), which
runs prior to feature patching. If the kernel is built with CONFIG_JUMP_LABEL=y
and CONFIG_JUMP_LABEL_FEATURE_CHECKS=y then we will potentially get the
wrong value.

If we also have CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG=y we get a warning
and backtrace:

  Warning! mmu_has_feature() used prior to jump label init!
  CPU: 0 PID: 0 Comm: swapper Not tainted 4.11.0-rc4-gccN-next-20170331-g6af2434 #1
  Call Trace:
  [c000000000fc3d50] [c000000000a26c30] .dump_stack+0xa8/0xe8 (unreliable)
  [c000000000fc3de0] [c00000000002e6b8] .setup_initial_memory_limit+0xa4/0x104
  [c000000000fc3e60] [c000000000d5c23c] .early_init_devtree+0xd0/0x2f8
  [c000000000fc3f00] [c000000000d5d3b0] .early_setup+0x90/0x11c
  [c000000000fc3f90] [c000000000000520] start_here_multiplatform+0x68/0x80

Fix it by using early_mmu_has_feature().

Fixes: c12e6f24 ("powerpc: Add option to use jump label for mmu_has_feature()")
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

These files don't seem to have any need for asm/debug.h, now that all it
includes are the debugger hooks and breakpoint definitions.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

powerpc_debugfs_root is the dentry representing the root of the
"powerpc" directory tree in debugfs.

Currently it sits in asm/debug.h, a long with some other things that
have "debug" in the name, but are otherwise unrelated.

Pull it out into a separate header, which also includes linux/debugfs.h,
and convert all the users to include debugfs.h instead of debug.h.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

In the recent commit 1ab66d1f ("powerpc/powernv: Introduce address
translation services for Nvlink2") the NPU code gained a dependency on MMU
notifiers.

All our defconfigs have KVM enabled, which selects MMU_NOTIFIER, but if KVM is
not enabled then the build breaks.

Fix it by always selecting MMU_NOTIFIER when we're building powernv.

Fixes: 1ab66d1f ("powerpc/powernv: Introduce address translation services for Nvlink2")
Signed-off-by: NAlistair Popple <alistair@popple.id.au>
[mpe: Reword change log]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

For a tlbiel with pid, we need to issue tlbiel with set number encoded. We
don't need to do ptesync for each of those. Instead we need one for the entire
tlbiel pid operation.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

For fullmm tlb flush, we do a flush with RIC_FLUSH_ALL which will invalidate all
related caches (radix__tlb_flush()). Hence the pwc flush is not needed.
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

We need to set LPES in order for normal external interrupts (0x500)
to be directed to the guest while running in guest state.

We also need HEIC set to prevent them to be sent to the host while
in host state.

With XIVE the host never gets one of these and wouldn't know how to
handle it. All host external interrupts come in via the new
hypervisor virtualization interrupts vector.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

We have all sort of variants of MMIO accessors for the real mode
instructions. This creates a clean set of accessors based on
Linux normal naming conventions, replacing all occurrences of
the old ones in the tree.

I have purposefully removed the "out/in" variants in favor of
only including __raw variants. Any code using these is already
pretty much hand tuned to operate in a very specific environment.
I've fixed up the 2 users (only one of them actually needed
a barrier in the first place).
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The function doesn't exist anymore
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

It's only used within the same file it's defined
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

We traditionally have linux/ before asm/
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The XIVE interrupt controller is the new interrupt controller
found in POWER9. It supports advanced virtualization capabilities
among other things.

Currently we use a set of firmware calls that simulate the old
"XICS" interrupt controller but this is fairly inefficient.

This adds the framework for using XIVE along with a native
backend which OPAL for configuration. Later, a backend allowing
the use in a KVM or PowerVM guest will also be provided.

This disables some fast path for interrupts in KVM when XIVE is
enabled as these rely on the firmware emulation code which is no
longer available when the XIVE is used natively by Linux.

A latter patch will make KVM also directly exploit the XIVE, thus
recovering the lost performance (and more).
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
[mpe: Fixup pr_xxx("XIVE:"...), don't split pr_xxx() strings,
 tweak Kconfig so XIVE_NATIVE selects XIVE and depends on POWERNV,
 fix build errors when SMP=n, fold in fixes from Ben:
   Don't call cpu_online() on an invalid CPU number
   Fix irq target selection returning out of bounds cpu#
   Extra sanity checks on cpu numbers
 ]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Some powerpc platforms use this to move IRQs away from a CPU being
unplugged. This function has several bugs such as not taking the right
locks or failing to NULL check pointers.

There's a new generic function doing exactly the same thing without all
the bugs, so let's use it instead.

mpe: The obvious place for the select of GENERIC_IRQ_MIGRATION is on
HOTPLUG_CPU, but that doesn't work. On some configs PM_SLEEP_SMP will
select HOTPLUG_CPU even though its dependencies are not met, which means
the select of GENERIC_IRQ_MIGRATION doesn't happen. That leads to the
build breaking. Fix it by moving the select of GENERIC_IRQ_MIGRATION to
SMP.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Some platforms (will) need to perform allocations before bringing
a new CPU online. Doing it from smp_ops->setup_cpu is the wrong
thing to do:

 - It has no useful failure path (too late)
 - Calling any allocator will enable interrupts prematurely
   causing problems with large decrementer among others

Instead, add a new callback that is called from __cpu_up (so from
the context trying to online the new CPU) at a point where we
can safely allocate and handle failures.

This will be used by XIVE support.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Add 32 and 8 bit variants
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

New versions of OPAL have a device node /ibm,opal/firmware/exports, each
property of which describes a range of memory in OPAL that Linux might
want to export to userspace for debugging.

This patch adds a sysfs file under 'opal/exports' for each property
found there, and makes it read-only by root.
Signed-off-by: NMatt Brown <matthew.brown.dev@gmail.com>
[mpe: Drop counting of props, rename to attr, free on sysfs error, c'log]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

When booting very large systems with a large initrd, we run out of
space early in boot for either RTAS or the flattened device tree (FDT).
Boot fails with messages like:

	Could not allocate memory for RTAS
or
	No memory for flatten_device_tree (no room)

Increasing the minimum RMA size to 512MB fixes the problem. This
should not have an impact on smaller LPARs (with 256MB memory),
as the firmware will cap the RMA to the memory assigned to the LPAR.

Fix is based on input/discussions with Michael Ellerman. Thanks to
Praveen K. Pandey for testing on a large system.
Reported-by: NPraveen K. Pandey <preveen.pandey@in.ibm.com>
Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Nvlink2 supports address translation services (ATS) allowing devices
to request address translations from an mmu known as the nest MMU
which is setup to walk the CPU page tables.

To access this functionality certain firmware calls are required to
setup and manage hardware context tables in the nvlink processing unit
(NPU). The NPU also manages forwarding of TLB invalidates (known as
address translation shootdowns/ATSDs) to attached devices.

This patch exports several methods to allow device drivers to register
a process id (PASID/PID) in the hardware tables and to receive
notification of when a device should stop issuing address translation
requests (ATRs). It also adds a fault handler to allow device drivers
to demand fault pages in.
Signed-off-by: NAlistair Popple <alistair@popple.id.au>
[mpe: Fix up comment formatting, use flush_tlb_mm()]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The pnv_pci_get_{gpu|npu}_dev functions are used to find associations
between nvlink PCIe devices and standard PCIe devices. However they
lacked basic sanity checking which results in NULL pointer
dereferencing if they are incorrect called can be harder to spot than
an explicit WARN_ON.
Signed-off-by: NAlistair Popple <alistair@popple.id.au>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The code to fix the problem it describes was removed in commit
c40785ad ("powerpc/dart: Use a cachable DART"), and it uses the
stupid comment style. Away it goooooooooooooes!
Signed-off-by: NOliver O'Halloran <oohall@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Early on in do_page_fault() we call store_updates_sp(), regardless of
the type of exception. For an instruction miss this doesn't make
sense, because we only use this information to detect if a data miss
is the result of a stack expansion instruction or not.

Worse still, it results in a data miss within every userspace
instruction miss handler, because we try and load the very instruction
we are about to install a pte for!

A simple exec microbenchmark runs 6% faster on POWER8 with this fix:

 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>

int main(int argc, char *argv[])
{
	unsigned long left = atol(argv[1]);
	char leftstr[16];

	if (left-- == 0)
		return 0;

	sprintf(leftstr, "%ld", left);
	execlp(argv[0], argv[0], leftstr, NULL);
	perror("exec failed\n");

	return 0;
}

Pass the number of iterations on the command line (eg 10000) and time
how long it takes to execute.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

For an MCE (Machine Check Exception) that hits while in user mode
MSR(PR=1), print the task info to the console MCE error log. This may
help to identify an application that triggered the MCE.

After this patch the MCE console looks like:

  Severe Machine check interrupt [Recovered]
    NIP: [0000000010039778] PID: 762 Comm: ebizzy
    Initiator: CPU
    Error type: SLB [Multihit]
      Effective address: 0000000010039778

  Severe Machine check interrupt [Not recovered]
    NIP: [0000000010039778] PID: 763 Comm: ebizzy
    Initiator: CPU
    Error type: UE [Page table walk ifetch]
      Effective address: 0000000010039778
  ebizzy[763]: unhandled signal 7 at 0000000010039778 nip 0000000010039778 lr 0000000010001b44 code 30004
Signed-off-by: NMahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>