This fixes the following warning with GCC 4.6:

mm/migrate.o: warning: objtool: migrate_misplaced_transhuge_page()+0x71: unreachable instruction

The problem is that the compiler merged identical annotate_unreachable()
inline asm blocks, resulting in a missing 'unreachable' annotation.

This problem happened before, and was partially fixed with:

3d1e236022cc ("objtool: Prevent GCC from merging annotate_unreachable()")

That commit tried to ensure that each instance of the
annotate_unreachable() inline asm statement has a unique label. It used
the __LINE__ macro to generate the label number. However, even the line
number isn't necessarily unique when used in an inline function with
multiple callers (in this case, __alloc_pages_node()'s use of
VM_BUG_ON).

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kbuild-all@01.org
Cc: tipbuild@zytor.com
Fixes: 3d1e236022cc ("objtool: Prevent GCC from merging annotate_unreachable()")
Link: http://lkml.kernel.org/r/20171103221941.cajpwszir7ujxyc4@treble
Signed-off-by: Ingo Molnar <mingo@kernel.org>

This fixes the following warning:

warning: objtool: x86 instruction decoder differs from kernel

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/013315a808ccf5580abc293808827c8e2b5e1354.1509719152.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

We want to fix an objtool build warning that got introduced in the latest upstream kernel.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

Guenter reported:
There is still a problem. When running
echo 6 > /proc/sys/kernel/watchdog_thresh
echo 5 > /proc/sys/kernel/watchdog_thresh
repeatedly, the message

NMI watchdog: Enabled. Permanently consumes one hw-PMU counter.

stops after a while (after ~10-30 iterations, with fluctuations).
Maybe watchdog_cpus needs to be atomic ?

That's correct as this again is affected by the asynchronous nature of the
smpboot thread unpark mechanism.

CPU 0 CPU1 CPU2
write(watchdog_thresh, 6)
stop()
park()
update()
start()
unpark()
thread->unpark()
cnt++;
write(watchdog_thresh, 5) thread->unpark()
stop()
park() thread->park()
cnt--; cnt++;
update()
start()
unpark()

That's not a functional problem, it just affects the informational message.

Convert watchdog_cpus to atomic_t to prevent the problem

Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20171101181126.j727fqjmdthjz4xk@redhat.com

For some odd historical reason, we preprocessed the linker scripts with
"-C", which keeps comments around. That makes no sense, since the
comments are not meaningful for the build anyway.

And it actually breaks things, since linker scripts can't have C++ style
"//" comments in them, so keeping comments after preprocessing now
limits us in odd and surprising ways in our header files for no good
reason.

The -C option goes back to pre-git and pre-bitkeeper times, but seems to
have been historically used (along with "-traditional") for some
odd-ball architectures (ia64, MIPS and SH). It probably didn't matter
back then either, but might possibly have been used to minimize the
difference between the original file and the pre-processed result.

The reason for this may be lost in time, but let's not perpetuate it
only because we can't remember why we did this crazy thing.

This was triggered by the recent addition of SPDX lines to the source
tree, where people apparently were confused about why header files
couldn't use the C++ comment format.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Greg KH <gregkh@linuxfoundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Guenter reported a crash in the watchdog/perf code, which is caused by
cleanup() and enable() running concurrently. The reason for this is:

The watchdog functions are serialized via the watchdog_mutex and cpu
hotplug locking, but the enable of the perf based watchdog happens in
context of the unpark callback of the smpboot thread. But that unpark
function is not synchronous inside the locking. The unparking of the thread
just wakes it up and leaves so there is no guarantee when the thread is
executing.

If it starts running _before_ the cleanup happened then it will create a
event and overwrite the dead event pointer. The new event is then cleaned
up because the event is marked dead.

lock(watchdog_mutex);
lockup_detector_reconfigure();
cpus_read_lock();
stop();
park()
update();
start();
unpark()
cpus_read_unlock(); thread runs()
overwrite dead event ptr
cleanup();
free new event, which is active inside perf....
unlock(watchdog_mutex);

The park side is safe as that actually waits for the thread to reach
parked state.

Commit a33d44843d45 removed the protection against this kind of scenario
under the stupid assumption that the hotplug serialization and the
watchdog_mutex cover everything.

Bring it back.

Reverts: a33d44843d45 ("watchdog/hardlockup/perf: Simplify deferred event destroy")
Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Thomas Feels-stupid Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Don Zickus <dzickus@redhat.com>
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1710312145190.1942@nanos

This reverts commit 51204e0639c49ada02fd823782ad673b6326d748.

There wasn't really any good reason for it, and people are complaining
(rightly) that it broke existing practice.

Cc: Len Brown <len.brown@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Dmitry (through syzbot) reported being able to trigger the WARN in
get_pi_state() and a use-after-free on:

raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);

Both are due to this race:

exit_pi_state_list() put_pi_state()

lock(&curr->pi_lock)
while() {
pi_state = list_first_entry(head);
hb = hash_futex(&pi_state->key);
unlock(&curr->pi_lock);

dec_and_test(&pi_state->refcount);

lock(&hb->lock)
lock(&pi_state->pi_mutex.wait_lock) // uaf if pi_state free'd
lock(&curr->pi_lock);

....

unlock(&curr->pi_lock);
get_pi_state(); // WARN; refcount==0

The problem is we take the reference count too late, and don't allow it
being 0. Fix it by using inc_not_zero() and simply retrying the loop
when we fail to get a refcount. In that case put_pi_state() should
remove the entry from the list.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Gratian Crisan <gratian.crisan@ni.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: dvhart@infradead.org
Cc: syzbot <bot+2af19c9e1ffe4d4ee1d16c56ae7580feaee75765@syzkaller.appspotmail.com>
Cc: syzkaller-bugs@googlegroups.com
Cc: <stable@vger.kernel.org>
Fixes: c74aef2d06a9 ("futex: Fix pi_state->owner serialization")
Link: http://lkml.kernel.org/r/20171031101853.xpfh72y643kdfhjs@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Pull arm64 fix from Catalin Marinas:
"Check addr_limit in arm64 __dump_instr()"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: ensure __dump_instr() checks addr_limit

Pull power management fix from Rafael Wysocki:
"This fixes new breakage introduced by the most recent PM QoS fix in
which, embarrassingly enough, I forgot to update
dev_pm_qos_raw_read_value() to return the right default for devices
with no PM QoS constraints at all which prevents runtime PM from
suspending those devices (fix from Tero Kristo)"

* tag 'pm-urgent-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PM / QoS: Fix default runtime_pm device resume latency

Pull initial SPDX identifiers from Greg KH:
"License cleanup: add SPDX license identifiers to some files

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the
'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally
binding shorthand, which can be used instead of the full boiler plate
text.

This patch is based on work done by Thomas Gleixner and Kate Stewart
and Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset
of the use cases:

- file had no licensing information it it.

- file was a */uapi/* one with no licensing information in it,

- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to
license had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied
to a file was done in a spreadsheet of side by side results from of
the output of two independent scanners (ScanCode & Windriver)
producing SPDX tag:value files created by Philippe Ombredanne.
Philippe prepared the base worksheet, and did an initial spot review
of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537
files assessed. Kate Stewart did a file by file comparison of the
scanner results in the spreadsheet to determine which SPDX license
identifier(s) to be applied to the file. She confirmed any
determination that was not immediately clear with lawyers working with
the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:

- Files considered eligible had to be source code files.

- Make and config files were included as candidates if they contained
>5 lines of source

- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that
was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that
became the concluded license(s).

- when there was disagreement between the two scanners (one detected
a license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply
(and which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases,
confirmation by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.
The Windriver scanner is based on an older version of FOSSology in
part, so they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot
checks in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect
the correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial
patch version early this week with:

- a full scancode scan run, collecting the matched texts, detected
license ids and scores

- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct

- reviewing anything where there was no detection but the patch
license was not GPL-2.0 WITH Linux-syscall-note to ensure that the
applied SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>"

* tag 'spdx_identifiers-4.14-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
License cleanup: add SPDX license identifier to uapi header files with a license
License cleanup: add SPDX license identifier to uapi header files with no license
License cleanup: add SPDX GPL-2.0 license identifier to files with no license

It's possible for a user to deliberately trigger __dump_instr with a
chosen kernel address.

Let's avoid problems resulting from this by using get_user() rather than
__get_user(), ensuring that we don't erroneously access kernel memory.

Where we use __dump_instr() on kernel text, we already switch to
KERNEL_DS, so this shouldn't adversely affect those cases.

Fixes: 60ffc30d5652810d ("arm64: Exception handling")
Cc: stable@vger.kernel.org
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

It turns out that some drivers seem to think it's ok to remap page
ranges from within interrupts and even NMI's. That is definitely not
the case, since the page table build-up is simply not interrupt-safe.

This showed up in the zero-day robot that reported it for the ACPI APEI
GHES ("Generic Hardware Error Source") driver. Normally it had been
hidden by the fact that no page table operations had been needed because
the vmalloc area had been set up by other things.

Apparently due to a recent change to the GHEI driver: commit
77b246b32b2c ("acpi: apei: check for pending errors when probing GHES
entries") 0day actually caught a case during bootup whenthe ioremap
called down to page allocation. But that recent change only showed the
symptom, it wasn't the root cause of the problem.

Hopefully it is limited to just that one driver.

If you need to access random physical memory, you either need to ioremap
in process context, or you need to use the FIXMAP facility to set one
particular fixmap entry to the required mapping - that can be done safely.

Cc: Borislav Petkov <bp@suse.de>
Cc: Len Brown <lenb@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Tyler Baicar <tbaicar@codeaurora.org>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>