It has come to my attention that kprobe event stack tracing does not
work on powerpc. You can see with the following:

  # cd /sys/kernel/debug/tracing
  # echo stacktrace > trace_options
  # echo 'p kfree' > kprobe_events
  # echo 1 > events/kprobes/enable

Will print the following warning:
  save_stack_trace_regs() not implemented yet.

Although save_stack_trace() (which normal event stack traces use) is
implemented, save_stack_trace_regs() which kprobe events use is not.
This is a cheap attempt to implement that function.

Note, This may have issues if a task tries to get a stack trace from
another task with its regs, because it just passes in "current" to
save_context_stack(). But this does solve the issue with stack tracing
kprobe events.
Reported-by: Chunyu Hu <chuhu@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Commit 2fc251a8 ("powerpc: Copy only required pieces of the
mm_context_t to the paca") broke the build for CONFIG_PPC_STD_MMU_64=y
and CONFIG_PPC_MM_SLICES=n.

That only happens for a kernel built with 4K pages and HUGETLB disabled,
which is why we missed it.

Fix it by adding a mm_ctx_user_psize member to the paca and populating
it in the appropriate places.

Fixes: 2fc251a8 ("powerpc: Copy only required pieces of the mm_context_t to the paca")
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Presently when a user-space process issues CXL_IOCTL_START_WORK ioctl we
store the pid of the current task_struct and use it to get pointer to
the mm_struct of the process, while processing page or segment faults
from the capi card. However this causes issues when the thread that had
originally issued the start-work ioctl exits in which case the stored
pid is no more valid and the cxl driver is unable to handle faults as
the mm_struct corresponding to process is no more accessible.

This patch fixes this issue by using the mm_struct of the next alive
task in the thread group. This is done by iterating over all the tasks
in the thread group starting from thread group leader and calling
get_task_mm on each one of them. When a valid mm_struct is obtained the
pid of the associated task is stored in the context replacing the
exiting one for handling future faults.

The patch introduces a new function named get_mem_context that checks if
the current task pointed to by ctx->pid is dead? If yes it performs the
steps described above. Also a new variable cxl_context.glpid is
introduced which stores the pid of the thread group leader associated
with the context owning task.
Reported-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Reported-by: Frank Haverkamp <HAVERKAM@de.ibm.com>
Suggested-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Reviewed-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Reviewed-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Fix off-by-one error in opal_mce_check_early_recovery() when checking
whether the NIP falls within OPAL space.
Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

A few of the config prompts for powerpc self-tests have periods at the
end, which is inconsistent with the rest of the prompts. Remove the
periods.
Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Only delay opal_rtc_read() when busy and are going to retry.

This has the advantage of possibly saving a massive 10ms off booting!

Kudos to Stewart for noticing.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Reviewed-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

On BMC machines, console output is controlled by the OPAL firmware and is
only flushed when its pollers are called.  When the kernel is in a panic
state, it no longer calls these pollers and thus console output does not
completely flush, causing some output from the panic to be lost.

Output is only actually lost when the kernel is configured to not power off
or reboot after panic (i.e. CONFIG_PANIC_TIMEOUT is set to 0) since OPAL
flushes the console buffer as part of its power down routines.  Before this
patch, however, only partial output would be printed during the timeout wait.

This patch adds a new kmsg_dumper which gets called at panic time to ensure
panic output is not lost.  It accomplishes this by calling OPAL_CONSOLE_FLUSH
in the OPAL API, and if that is not available, the pollers are called enough
times to (hopefully) completely flush the buffer.

The flushing mechanism will only affect output printed at and before the
kmsg_dump call in kernel/panic.c:panic().  As such, the "end Kernel panic"
message may still be truncated as follows:

>Call Trace:
>[c000000f1f603b00] [c0000000008e9458] dump_stack+0x90/0xbc (unreliable)
>[c000000f1f603b30] [c0000000008e7e78] panic+0xf8/0x2c4
>[c000000f1f603bc0] [c000000000be4860] mount_block_root+0x288/0x33c
>[c000000f1f603c80] [c000000000be4d14] prepare_namespace+0x1f4/0x254
>[c000000f1f603d00] [c000000000be43e8] kernel_init_freeable+0x318/0x350
>[c000000f1f603dc0] [c00000000000bd74] kernel_init+0x24/0x130
>[c000000f1f603e30] [c0000000000095b0] ret_from_kernel_thread+0x5c/0xac
>---[ end Kernel panic - not

This functionality is implemented as a kmsg_dumper as it seems to be the
most sensible way to introduce platform-specific functionality to the
panic function.
Signed-off-by: Russell Currey <ruscur@russell.cc>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Currently we copy the whole mm_context_t to the paca but only access a
few bits of it.  This is wasteful of space paca and also takes quite
some time in the hot path of context switching.

This patch pulls in only the required bits from the mm_context_t to
the paca and on context switch, copies only those.

Benchmarking this (On top of Anton's recent MSR context switching
changes [1]) using processes and yield shows an improvement of almost
3% on POWER8:

  http://ozlabs.org/~anton/junkcode/context_switch2.c
  ./context_switch2 --test=yield --process 0 0

1. https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-October/135700.htmlSigned-off-by: Michael Neuling <mikey@neuling.org>
[mpe: Rename paca fields to be mm_ctx_foo rather than context_foo]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This adds a function to copy the mm->context to the paca.  This is
only a basic conversion for now but will be used more extensively in
the next patch.

This also adds #ifdef CONFIG_PPC_BOOK3S around this code since it's
not used elsewhere.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

cppcheck picked up that there were a couple of missing va_end()
calls in functions using va_start().
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Enable new kernel cpu hotplug functionality by allowing cpu dlpar requests
to be initiated from sysfs.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Add the ability to hotplug add cpus via rtas hotplug events by either
specifying the drc index of the CPU to add, or providing a count of the
number of CPUs to add.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Add the ability to dlpar remove CPUs via hotplug rtas events, either by
specifying the drc-index of the CPU to remove or providing a count of cpus
to remove.

To remove multiple cpus in a single request we create a list of possible
DR (Dynamic Reconfiguration) cpus and their drc indexes that can be
removed.  We can then traverse the list remove each cpu and easily clean
up in any cases of failure.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Update the cpu dlpar add/remove paths to do better error recovery when
a failure occurs during the add/remove operation.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Re-factor the cpu hotplug code to support doing cpu hotplug completely in
the kernel and using the existing sysfs probe/release interfaces. This
patch pulls out pieces of existing cpu hotplug code into common routines,
dlpar_cpu_add() and dlpar_cpu_remove(), to be used by both interfaces.
There are no functional changes introduced.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

No functional changes, this patch is simply a move of the cpu hotplug
code from pseries/dlpar.c to pseries/hotplug-cpu.c. This is in an effort
to consolidate all of the cpu hotplug code in a common place.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

When DLPAR adding a CPU we should verify that the CPU does not already
exist. Failure to do so can generate a kernel oops;

[    9.465585] kernel BUG at arch/powerpc/platforms/pseries/dlpar.c:382!
[    9.465796] Oops: Exception in kernel mode, sig: 5 [#1]

This oops can be generated by causing a probe to be performed on a cpu
by writing to the sysfs cpu probe file (/sys/devices/system/cpu/probe).
This patch adds a check for the existence of cpu prior to probing the cpu
so userspace doing the wrong thing won't trigger a BUG_ON().
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

PPC476FPE has a different PVR from previous PPC476 processors. The
kexec code checks the PVR in order to correctly setup the MMU. When
the initial support for 476FPE processors was added the corresponding
change in the kexec code was missed. This patch simply adds the check
and solves the following bug on kexec:

kexec: Starting new kernel
Bye!
Unable to handle kernel paging request for instruction fetch
Faulting instruction address: 0xee9a50f8
cpu 0x0: Vector: 400 (Instruction Access) at [ee9d7d20]
    pc: ee9a50f8
    lr: ee9a50e4
    sp: ee9d7dd0
    msr: 21020
    current = 0xee40f000
    pid   = 960, comm = kexec
enter ? for help
[link register   ] ee9a50e4
[ee9d7dd0] c0013748 default_machine_kexec+0x58/0x70 (unreliable)
[ee9d7df0] c0012f04 machine_kexec+0x34/0x40
[ee9d7e00] c00aa1ec kernel_kexec+0x9c/0xb0
[ee9d7e20] c005d704 SyS_reboot+0x1f4/0x220
[ee9d7f40] c000db68 ret_from_syscall+0x0/0x3c
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

NVLink is a high speed interconnect that is used in conjunction with a
PCI-E connection to create an interface between CPU and GPU that
provides very high data bandwidth. A PCI-E connection to a GPU is used
as the control path to initiate and report status of large data
transfers sent via the NVLink.

On IBM Power systems the NVLink processing unit (NPU) is similar to
the existing PHB3. This patch adds support for a new NPU PHB type. DMA
operations on the NPU are not supported as this patch sets the TCE
translation tables to be the same as the related GPU PCIe device for
each NVLink. Therefore all DMA operations are setup and controlled via
the PCIe device.

EEH is not presently supported for the NPU devices, although it may be
added in future.
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Move __raw_rm_writeq() from platforms/powernv/pci-ioda.c to
include/asm/io.h so that it can be used by other code.
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This commit removed the pcidev field from struct pci_dn as it was no
longer in use by the kernel. However to support finding the
association of Nvlink devices to GPU devices from the device-tree this
field is required.

This reverts commit 250c7b27 ("powerpc/pci: Remove unused struct
pci_dn.pcidev field").
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

The name of PCI root bus's M64 resource isn't initialized properly.
When dumping "/proc/iomem", "<BAD>" is seen for those M64 resources
on PCI root buses.

   ~# cat /proc/iomem | grep -e "BAD"
   3b0000000000-3b0fefffffff : <BAD>
   3b1000000000-3b1fefffffff : <BAD>
   3c0000000000-3c0fefffffff : <BAD>
   3c1000000000-3c1fefffffff : <BAD>
   3c2000000000-3c2fefffffff : <BAD>

This fixes the issue by setting the name of PCI root bus's M64
resource to that of PHB's device node full name. With the patch,
no "<BAD>" is seen from "/proc/iomem".
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

User space checkpoint and restart tool (CRIU) needs the page's change
to be soft tracked. This allows to do a pre checkpoint and then dump
only touched pages.

This is done by using a newly assigned PTE bit (_PAGE_SOFT_DIRTY) when
the page is backed in memory, and a new _PAGE_SWP_SOFT_DIRTY bit when
the page is swapped out.

To introduce a new PTE _PAGE_SOFT_DIRTY bit value common to hash 4k
and hash 64k pte, the bits already defined in hash-*4k.h should be
shifted left by one.

The _PAGE_SWP_SOFT_DIRTY bit is dynamically put after the swap type in
the swap pte. A check is added to ensure that the bit is not
overwritten by _PAGE_HPTEFLAGS.
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
CC: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

The STD_EXCEPTION_PSERIES macro takes both a vector number, and a
location (memory address). However both are always identical, so combine
them to save repeating ourselves.

This does mean an exception handler must always exist at the location in
memory that matches its vector number. But that's OK because this is the
"STD" macro (standard), which does exactly that. We have other macros
for the other cases, eg. STD_EXCEPTION_PSERIES_OOL (out of line).
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This is only used in one location, open code it.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

HMT_MEDIUM_LOW_HAS_PPR is only used in once place, open code it.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

HMT_MEDIUM_PPR_DISCARD is a macro which is present at the start of most
of our first level exception handlers. It conditionally executes a
HMT_MEDIUM instruction, which sets the processor priority to medium.

On on modern systems, ie. Power7 and later, it is nop'ed out at boot.
All it does is make the exception vectors more cramped, and consume 4
bytes of icache.

On old systems it has the effect of boosting the processor priority at
the start of exception processing. If we were previously in the idle
loop for example, we may be at low or very low priority. This is
desirable as we want to process the exception as fast as possible.

However looking closely at the generated code, we see that in all cases
we execute another HMT_MEDIUM just four instructions later. With code
patching applied, the final code on an old (Power6) system will look
like, eg:

  c000000000000300 <data_access_pSeries>:
  c000000000000300:	7c 42 13 78	mr	r2,r2		<-
  c000000000000304:	7d b2 43 a6	mtsprg	2,r13
  c000000000000308:	7d b1 42 a6	mfsprg	r13,1
  c00000000000030c:	f9 2d 00 80	std	r9,128(r13)
  c000000000000310:	60 00 00 00	nop
  c000000000000314:	7c 42 13 78	mr	r2,r2		<-

So I suggest that the added code complexity of HMT_MEDIUM_PPR_DISCARD is
not justified by the benefit of boosting the processor priority for the
duration of four instructions, and therefore we drop it.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

There are no longer any users of enter_rtas() outside of rtas.c, so make
it "private", by moving the declaration inside rtas.c. Hopefully this
will encourage people to use one of the wrappers which takes the sharp
edges off the RTAS calling sequence.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Although call_rtas_display_status() does actually want to use the
regular RTAS locking, it doesn't want the extra logic that is in
rtas_call(), so currently it open codes the logic.

Instead we can use rtas_call_unlocked(), after taking the RTAS lock.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Avoid open coding the logic by using rtas_call_unlocked().
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Avoid open coding the logic by using rtas_call_unlocked().
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Most users of RTAS (Run-Time Abstraction Services) use rtas_call(),
which deals with locking as well as endian handling.

However we have two users outside of rtas.c that can't use rtas_call()
because they have different locking requirements.

The hotplug CPU code can't take the RTAS lock because the CPU would go
offline with the lock held and no other CPUs would be able to call RTAS
until the CPU came back online.

The xmon code doesn't want to take the lock because it would risk dead
locking when we are trying to recover from a crash.

Both sites required multiple patches when we added little endian
support, proving that programmers can't do endian right.

Although that ship has sailed, we can still clean the code up by
providing an unlocked version of rtas_call() which avoids the need to
open code the logic elsewhere.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Long ago, only in the lab, there was OPALv1 and OPALv2. Now there is
just OPALv3, with nobody ever expecting anything on pre-OPALv3 to
be cared about or supported by mainline kernels.

So, let's remove FW_FEATURE_OPALv3 and instead use FW_FEATURE_OPAL
exclusively.
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

OPALv2 only ever existed in the lab and didn't escape to the world.
All OPAL systems in the wild are OPALv3.

The probability of there being an OPALv2 system still powered on
anywhere inside IBM is approximately zero, let alone anyone
expecting to run mainline kernels.

So, start to remove references to OPALv2.
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

The OpenPower Abstraction Layer firmware went through a couple
of iterations in the lab before being released. What we now know
as OPAL advertises itself as OPALv3.

OPALv2 and OPALv1 never made it outside the lab, and the possibility
of anyone at all ever building a mainline kernel today and expecting
it to boot on such hardware is zero.
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

HMIs (Hypervisor Management|Maintenance Interrupts) are a class of interrupt
on POWER systems.

HMI support has traditionally been exceptionally difficult to test, however
Skiboot ships a tool that, with the correct magic numbers, will inject them.

This, therefore, is a first pass at a script to inject HMIs and monitor
Linux's response. It injects an HMI on each core on every chip in turn
It then watches dmesg to see if it's acknowledged by Linux.

On a Tuletta, I observed that we see 8 (or sometimes 9 or more) events per
injection, regardless of SMT setting, so we wait for 8 before progressing.

It sits in a new scripts/ directory in selftests/powerpc, because it's not
designed to be run as part of the regular make selftests process. In
particular, it is quite possibly going to end up garding lots of your CPUs,
so it should only be run if you know how to undo that.

CC: Mahesh J Salgaonkar <mahesh.salgaonkar@in.ibm.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Simply because it touches more code paths that way, and therefore tests
more things.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Anton Blanchard <anton@samba.org>

For ease of use make the context_switch test do something useful when
called with no arguments.

Default to a 30 second run, using threads, doing yield, and use any
online cpu. Make it print out what it's doing to avoid confusion.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Anton Blanchard <anton@samba.org>

This gets referred to a lot in commit messages, so let's pull it into
the selftests.

Almost vanilla from: http://ozlabs.org/~anton/junkcode/context_switch2.cSigned-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Anton Blanchard <anton@samba.org>

We want to use this in another test, so make it available at the top of
the powerpc selftests tree.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>