Pull powerpc fixes from Michael Ellerman:

 "One notable fix for kexec on Power9, where we were not clearing MMU
  PID properly which sometimes leads to hangs. Finally debugged to a
  root cause by Nick.

  A revert of a patch which tried to rework our panic handling to get
  more output on the console, but inadvertently broke reporting the
  panic to the hypervisor, which apparently people care about.

  Then a fix for an oops in the PMU code, and finally some s/%p/%px/ in
  xmon.

  Thanks to: David Gibson, Nicholas Piggin, Ravi Bangoria"

* tag 'powerpc-4.15-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/xmon: Don't print hashed pointers in xmon
  powerpc/64s: Initialize ISAv3 MMU registers before setting partition table
  Revert "powerpc: Do not call ppc_md.panic in fadump panic notifier"
  powerpc/perf: Fix oops when grouping different pmu events

Pull s390 fixes from Martin Schwidefsky:

 - three more patches in regard to the SPDX license tags. The missing
   tags for the files in arch/s390/kvm will be merged via the KVM tree.
   With that all s390 related files should have their SPDX tags.

 - a patch to get rid of 'struct timespec' in the DASD driver.

 - bug fixes

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390: fix compat system call table
  s390/mm: fix off-by-one bug in 5-level page table handling
  s390: Remove redudant license text
  s390: add a few more SPDX identifiers
  s390/dasd: prevent prefix I/O error
  s390: always save and restore all registers on context switch
  s390/dasd: remove 'struct timespec' usage
  s390/qdio: restrict target-full handling to IQDIO
  s390/qdio: consider ERROR buffers for inbound-full condition
  s390/virtio: add BSD license to virtio-ccw

Pull arm64 fixes from Will Deacon:
 "Fix some more FP register fallout from the SVE patches and also some
  problems with the PGD tracking in our software PAN emulation code,
  after we received a crash report from a 3.18 kernel running a
  backport.

  Summary:

   - fix SW PAN pgd shadowing for kernel threads, EFI and exiting user
     tasks

   - fix FP register leak when a task_struct is re-allocated

   - fix potential use-after-free in FP state tracking used by KVM"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64/sve: Avoid dereference of dead task_struct in KVM guest entry
  arm64: SW PAN: Update saved ttbr0 value on enter_lazy_tlb
  arm64: SW PAN: Point saved ttbr0 at the zero page when switching to init_mm
  arm64: fpsimd: Abstract out binding of task's fpsimd context to the cpu.
  arm64: fpsimd: Prevent registers leaking from dead tasks

Pull ACPI fix from Rafael Wysocki:
 "This fixes an out of bounds warning from KASAN in the ACPI CPPC
  driver"

* tag 'acpi-4.15-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI / CPPC: Fix KASAN global out of bounds warning

Pull power management fix from Rafael Wysocki:
 "This fixes an issue in the device runtime PM framework that prevents
  customer devices from resuming if runtime PM is disabled for one or
  more of their supplier devices (as reflected by device links between
  those devices)"

* tag 'pm-4.15-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PM / runtime: Fix handling of suppliers with disabled runtime PM

When wiring up the socket system calls the compat entries were
incorrectly set. Not all of them point to the corresponding compat
wrapper functions, which clear the upper 33 bits of user space
pointers, like it is required.

Fixes: 977108f8

 ("s390: wire up separate socketcalls system calls")
Cc: <stable@vger.kernel.org> # v4.3+
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Pull kgdb fixes from Jason Wessel:

 - Fix long standing problem with kdb kallsyms_symbol_next() return
   value

 - Add new co-maintainer Daniel Thompson

* tag 'for_linus-4.15-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb:
  kgdb/kdb/debug_core: Add co-maintainer Daniel Thompson
  kdb: Fix handling of kallsyms_symbol_next() return value

It's a user pointer, and while the permissions of the file are pretty
questionable (should it really be readable to everybody), hashing the
pointer isn't going to be the solution.

We should take a closer look at more of the /proc/<pid> file permissions
in general.  Sure, we do want many of them to often be readable (for
'ps' and friends), but I think we should probably do a few conversions
from S_IRUGO to S_IRUSR.

Reported-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull m68knommu fixes from Greg Ungerer:
 "There are two fixes here. One to add a missing linker section to the
  m68k architecture linker scripts, the other to fix a defconfig build
  problem"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu:
  m68k/defconfig: fix stmark2 broken local compilation
  m68k: add missing SOFTIRQENTRY_TEXT linker section

Pull misc x86 fixes from Ingo Molnar:

 - make CR4 handling irq-safe, which bug vmware guests ran into

 - don't crash on early IRQs in Xen guests

 - don't crash secondary CPU bringup if #UD assisted WARN()ings are
   triggered

 - make X86_BUG_FXSAVE_LEAK optional on newer AMD CPUs that have the fix

 - fix AMD Fam17h microcode loading

 - fix broadcom_postcore_init() if ACPI is disabled

 - fix resume regression in __restore_processor_context()

 - fix Sparse warnings

 - fix a GCC-8 warning

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/vdso: Change time() prototype to match __vdso_time()
  x86: Fix Sparse warnings about non-static functions
  x86/power: Fix some ordering bugs in __restore_processor_context()
  x86/PCI: Make broadcom_postcore_init() check acpi_disabled
  x86/microcode/AMD: Add support for fam17h microcode loading
  x86/cpufeatures: Make X86_BUG_FXSAVE_LEAK detectable in CPUID on AMD
  x86/idt: Load idt early in start_secondary
  x86/xen: Support early interrupts in xen pv guests
  x86/tlb: Disable interrupts when changing CR4
  x86/tlb: Refactor CR4 setting and shadow write

Pull CPU hotplug fix from Ingo Molnar:
 "A single fix moving the smp-call queue flush step to the intended
  point in the state machine"

* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  smp/hotplug: Move step CPUHP_AP_SMPCFD_DYING to the correct place

Pull scheduler fixes from Ingo Molnar:
 "This includes a fix for the add_wait_queue() queue ordering brown
  paperbag bug, plus PELT accounting fixes for cgroups scheduling
  artifacts"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Update and fix the runnable propagation rule
  sched/wait: Fix add_wait_queue() behavioral change

Pull perf fixes from Ingo Molnar:
 "This includes perf namespace support kernel side fixes, plus an
  accumulated set of perf tooling fixes - including UAPI header
  synchronization that should make the perf build less noisy"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (31 commits)
  tooling/headers: Synchronize updated s390 and x86 UAPI headers
  tools headers: Syncronize mman.h ABI header
  tools headers: Synchronize prctl.h ABI header
  tools headers: Synchronize KVM arch ABI headers
  tools headers: Synchronize drm/i915_drm.h
  tools headers uapi: Synchronize drm/drm.h
  tools headers: Synchronize perf_event.h header
  tools headers: Synchronize kernel ABI headers wrt SPDX tags
  tools/headers: Synchronize kernel x86 UAPI headers
  perf intel-pt: Bring instruction decoder files into line with the kernel
  perf test: Fix test 21 for s390x
  perf bench numa: Fixup discontiguous/sparse numa nodes
  perf top: Use signal interface for SIGWINCH handler
  perf top: Fix window dimensions change handling
  perf: Fix header.size for namespace events
  perf top: Ignore kptr_restrict when not sampling the kernel
  perf record: Ignore kptr_restrict when not sampling the kernel
  perf report: Ignore kptr_restrict when not sampling the kernel
  perf evlist: Add helper to check if attr.exclude_kernel is set in all evsels
  perf test shell: Fix test case probe libc's inet_pton on s390x
  ...

Pull lockdep fix from Ingo Molnar:
 "Fix a possible NULL dereference for the (rare) case when a task
  doesn't have ->xhlocks space allocated due to kmalloc() OOM-ing"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/lockdep: Fix possible NULL deref

Pull irq fixes from Ingo Molnar:
 "Two fixes: use bool type consistently, plus a irq_matrix_available()
  bugfix"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqdesc: Use bool return type instead of int
  genirq/matrix: Fix the precedence fix for real

Pull EFI fixes from Ingo Molnar:
 "Misc fixes: world-readable pointer removal from sysfs, a ESRT kfree()
  bug fix and a comment update"

* 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi: Add comment to avoid future expanding of sysfs systab
  efi/esrt: Use memunmap() instead of kfree() to free the remapping
  efi: Move some sysfs files to be read-only by root

Pull core fixes from Ingo Molnar:
 "Two fixes:

   - objtool cross-build fixes

   - removal of an obsolete CPU-hotplug state name from comments"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Fix 64-bit build on 32-bit host
  cpu/hotplug: Fix state name in takedown_cpu() comment

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

kallsyms_symbol_next() returns a boolean (true on success). Currently
kdb_read() tests the return value with an inequality that
unconditionally evaluates to true.

This is fixed in the obvious way and, since the conditional branch is
supposed to be unreachable, we also add a WARN_ON().

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

There were two trivial updates to these upstream UAPI headers:

  arch/s390/include/uapi/asm/kvm.h
  arch/s390/include/uapi/asm/kvm_perf.h
  arch/x86/lib/x86-opcode-map.txt

Synchronize them with their tooling copies.

(The x86 opcode map includes a new instruction pattern now.)

Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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

The new ORC unwinder breaks the build of a 64-bit kernel on a 32-bit
host.  Building the kernel on a i386 or x32 host fails with:

  orc_dump.c: In function 'orc_dump':
  orc_dump.c:105:26: error: passing argument 2 of 'elf_getshdrnum' from incompatible pointer type [-Werror=incompatible-pointer-types]
    if (elf_getshdrnum(elf, &nr_sections)) {
                            ^
  In file included from /usr/local/include/gelf.h:32:0,
                   from elf.h:22,
                   from warn.h:26,
                   from orc_dump.c:20:
  /usr/local/include/libelf.h:304:12: note: expected 'size_t * {aka unsigned int *}' but argument is of type 'long unsigned int *'
   extern int elf_getshdrnum (Elf *__elf, size_t *__dst);
              ^~~~~~~~~~~~~~
  orc_dump.c:190:17: error: format '%lx' expects argument of type 'long unsigned int', but argument 3 has type 'Elf64_Sxword {aka long long int}' [-Werror=format=]
      printf("%s+%lx:", name, rela.r_addend);
                 ~~^          ~~~~~~~~~~~~~
                 %llx

Fix the build failure.

Another problem is that if the user specifies HOSTCC or HOSTLD
variables, they are ignored in the objtool makefile.  Change the
Makefile to respect these variables.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sven Joachim <svenjoac@gmx.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 627fce14

 ("objtool: Add ORC unwind table generation")
Link: http://lkml.kernel.org/r/19f0e64d8e07e30a7b307cd010eb780c404fe08d.1512252895.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

gcc-8 warns that time() is an alias for __vdso_time() but the two
have different prototypes:

  arch/x86/entry/vdso/vclock_gettime.c:327:5: error: 'time' alias between functions of incompatible types 'int(time_t *)' {aka 'int(long int *)'} and 'time_t(time_t *)' {aka 'long int(long int *)'} [-Werror=attribute-alias]
   int time(time_t *t)
       ^~~~
  arch/x86/entry/vdso/vclock_gettime.c:318:16: note: aliased declaration here

I could not figure out whether this is intentional, but I see that
changing it to return time_t avoids the warning.

Returning 'int' from time() is also a bit questionable, as it causes an
overflow in y2038 even on 64-bit architectures that use a 64-bit time_t
type. On 32-bit architecture with 64-bit time_t, time() should always
be implement by the C library by calling a (to be added) clock_gettime()
variant that takes a sufficiently wide argument.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: http://lkml.kernel.org/r/20171204150203.852959-1-arnd@arndb.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

When deciding whether to invalidate FPSIMD state cached in the cpu,
the backend function sve_flush_cpu_state() attempts to dereference
__this_cpu_read(fpsimd_last_state).  However, this is not safe:
there is no guarantee that this task_struct pointer is still valid,
because the task could have exited in the meantime.

This means that we need another means to get the appropriate value
of TIF_SVE for the associated task.

This patch solves this issue by adding a cached copy of the TIF_SVE
flag in fpsimd_last_state, which we can check without dereferencing
the task pointer.

In particular, although this patch is not a KVM fix per se, this
means that this check is now done safely in the KVM world switch
path (which is currently the only user of this code).

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Pull IOMMU fix from Alex Williamson:
 "Fix VT-d handling of scatterlists where sg->offset exceeds PAGE_SIZE"

* tag 'iommu-v4.15-rc3' of git://github.com/awilliam/linux-vfio:
  iommu/vt-d: Fix scatterlist offset handling

Pull sound fixes from Takashi Iwai:
 "All fixes are small and for stable:

   - a PCM ioctl race fix

   - yet another USB-audio hardening for malicious descriptors

   - Realtek ALC257 codec support"

* tag 'sound-4.15-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: pcm: prevent UAF in snd_pcm_info
  ALSA: hda/realtek - New codec support for ALC257
  ALSA: usb-audio: Add check return value for usb_string()
  ALSA: usb-audio: Fix out-of-bound error
  ALSA: seq: Remove spurious WARN_ON() at timer check

Functions x86_vector_debug_show(), uv_handle_nmi() and uv_nmi_setup_common()
are local to the source and do not need to be in global scope, so make them
static.

Fixes up various sparse warnings.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Mike Travis <mike.travis@hpe.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Kosina <trivial@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russ Anderson <russ.anderson@hpe.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-janitors@vger.kernel.org
Cc: travis@sgi.com
Link: http://lkml.kernel.org/r/20171206173358.24388-1-colin.king@canonical.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

/sys/firmware/efi/systab shows several different values, it breaks sysfs
one file one value design.  But since there are already userspace tools
depend on it eg. kexec-tools so add code comment to alert future expanding
of this file.

Signed-off-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20171206095010.24170-4-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

The remapping result of memremap() should be freed with memunmap(), not kfree().

Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: <stable@vger.kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20171206095010.24170-3-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Thanks to the scripts/leaking_addresses.pl script, it was found that
some EFI values should not be readable by non-root users.

So make them root-only, and to do that, add a __ATTR_RO_MODE() macro to
make this easier, and use it in other places at the same time.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Cc: stable <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20171206095010.24170-2-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Unlike running, the runnable part can't be directly propagated through
the hierarchy when we migrate a task. The main reason is that runnable
time can be shared with other sched_entities that stay on the rq and
this runnable time will also remain on prev cfs_rq and must not be
removed.

Instead, we can estimate what should be the new runnable of the prev
cfs_rq and check that this estimation stay in a possible range. The
prop_runnable_sum is a good estimation when adding runnable_sum but
fails most often when we remove it. Instead, we could use the formula
below instead:

  gcfs_rq's runnable_sum = gcfs_rq->avg.load_sum / gcfs_rq->load.weight

which assumes that tasks are equally runnable which is not true but
easy to compute.

Beside these estimates, we have several simple rules that help us to filter
out wrong ones:

 - ge->avg.runnable_sum <= than LOAD_AVG_MAX
 - ge->avg.runnable_sum >= ge->avg.running_sum (ge->avg.util_sum << LOAD_AVG_MAX)
 - ge->avg.runnable_sum can't increase when we detach a task

The effect of these fixes is better cgroups balancing.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Chris Mason <clm@fb.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yuyang Du <yuyang.du@intel.com>
Link: http://lkml.kernel.org/r/1510842112-21028-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

The following cleanup commit:

  50816c48

 ("sched/wait: Standardize internal naming of wait-queue entries")

... unintentionally changed the behavior of add_wait_queue() from
inserting the wait entry at the head of the wait queue to the tail
of the wait queue.

Beyond a negative performance impact this change in behavior
theoretically also breaks wait queues which mix exclusive and
non-exclusive waiters, as non-exclusive waiters will not be
woken up if they are queued behind enough exclusive waiters.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-team@fb.com
Fixes: ("sched/wait: Standardize internal naming of wait-queue entries")
Link: http://lkml.kernel.org/r/a16c8ccffd39bd08fdaa45a5192294c784b803a7.1512544324.git.osandov@fb.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

We can't invalidate xhlocks when we've not yet allocated any.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Fixes: f52be570

 ("locking/lockdep: Untangle xhlock history save/restore from task independence")
Signed-off-by: Ingo Molnar <mingo@kernel.org>

CPUHP_AP_SCHED_MIGRATE_DYING doesn't exist, it looks like this was
supposed to refer to CPUHP_AP_SCHED_STARTING's teardown callback,
i.e. sched_cpu_dying().

Signed-off-by: Brendan Jackman <brendan.jackman@arm.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171206105911.28093-1-brendan.jackman@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

enter_lazy_tlb is called when a kernel thread rides on the back of
another mm, due to a context switch or an explicit call to unuse_mm
where a call to switch_mm is elided.

In these cases, it's important to keep the saved ttbr value up to date
with the active mm, otherwise we can end up with a stale value which
points to a potentially freed page table.

This patch implements enter_lazy_tlb for arm64, so that the saved ttbr0
is kept up-to-date with the active mm for kernel threads.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: <stable@vger.kernel.org>
Fixes: 39bc88e5

 ("arm64: Disable TTBR0_EL1 during normal kernel execution")
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Reported-by: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

update_saved_ttbr0 mandates that mm->pgd is not swapper, since swapper
contains kernel mappings and should never be installed into ttbr0. However,
this means that callers must avoid passing the init_mm to update_saved_ttbr0
which in turn can cause the saved ttbr0 value to be out-of-date in the context
of the idle thread. For example, EFI runtime services may leave the saved ttbr0
pointing at the EFI page table, and kernel threads may end up with stale
references to freed page tables.

This patch changes update_saved_ttbr0 so that the init_mm points the saved
ttbr0 value to the empty zero page, which always exists and never contains
valid translations. EFI and switch can then call into update_saved_ttbr0
unconditionally.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: <stable@vger.kernel.org>
Fixes: 39bc88e5

 ("arm64: Disable TTBR0_EL1 during normal kernel execution")
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Reported-by: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

There is currently some duplicate logic to associate current's
FPSIMD context with the cpu when loading FPSIMD state into the cpu
regs.

Subsequent patches will update that logic, so in order to ensure it
only needs to be done in one place, this patch factors the relevant
code out into a new function fpsimd_bind_to_cpu().

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Currently, loading of a task's fpsimd state into the CPU registers
is skipped if that task's state is already present in the registers
of that CPU.

However, the code relies on the struct fpsimd_state * (and by
extension struct task_struct *) to unambiguously identify a task.

There is a particular case in which this doesn't work reliably:
when a task exits, its task_struct may be recycled to describe a
new task.

Consider the following scenario:

 1) Task P loads its fpsimd state onto cpu C.
        per_cpu(fpsimd_last_state, C) := P;
        P->thread.fpsimd_state.cpu := C;

 2) Task X is scheduled onto C and loads its fpsimd state on C.
        per_cpu(fpsimd_last_state, C) := X;
        X->thread.fpsimd_state.cpu := C;

 3) X exits, causing X's task_struct to be freed.

 4) P forks a new child T, which obtains X's recycled task_struct.
	T == X.
	T->thread.fpsimd_state.cpu == C (inherited from P).

 5) T is scheduled on C.
	T's fpsimd state is not loaded, because
	per_cpu(fpsimd_last_state, C) == T (== X) &&
	T->thread.fpsimd_state.cpu == C.

        (This is the check performed by fpsimd_thread_switch().)

So, T gets X's registers because the last registers loaded onto C
were those of X, in (2).

This patch fixes the problem by ensuring that the sched-in check
fails in (5): fpsimd_flush_task_state(T) is called when T is
forked, so that T->thread.fpsimd_state.cpu == C cannot be true.
This relies on the fact that T is not schedulable until after
copy_thread() completes.

Once T's fpsimd state has been loaded on some CPU C there may still
be other cpus D for which per_cpu(fpsimd_last_state, D) ==
&X->thread.fpsimd_state.  But D is necessarily != C in this case,
and the check in (5) must fail.

An alternative fix would be to do refcounting on task_struct.  This
would result in each CPU holding a reference to the last task whose
fpsimd state was loaded there.  It's not clear whether this is
preferable, and it involves higher overhead than the fix proposed
in this patch.  It would also move all the task_struct freeing
work into the context switch critical section, or otherwise some
deferred cleanup mechanism would need to be introduced, neither of
which seems obviously justified.

Cc: <stable@vger.kernel.org>
Fixes: 005f78cd

 ("arm64: defer reloading a task's FPSIMD state to userland resume")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
[will: word-smithed the comment so it makes more sense]
Signed-off-by: Will Deacon <will.deacon@arm.com>

Since commit ad67b74d

 ("printk: hash addresses printed with %p")
pointers printed with %p are hashed, ie. you don't see the actual
pointer value but rather a cryptographic hash of its value.

In xmon we want to see the actual pointer values, because xmon is a
debugger, so replace %p with %px which prints the actual pointer
value.

We justify doing this in xmon because 1) xmon is a kernel crash
debugger, it's only accessible via the console 2) xmon doesn't print
to dmesg, so the pointers it prints are not able to be leaked that
way.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

kexec can leave MMU registers set when booting into a new kernel,
the PIDR (Process Identification Register) in particular. The boot
sequence does not zero PIDR, so it only gets set when CPUs first
switch to a userspace processes (until then it's running a kernel
thread with effective PID = 0).

This leaves a window where a process table entry and page tables are
set up due to user processes running on other CPUs, that happen to
match with a stale PID. The CPU with that PID may cause speculative
accesses that address quadrant 0 (aka userspace addresses), which will
result in cached translations and PWC (Page Walk Cache) for that
process, on a CPU which is not in the mm_cpumask and so they will not
be invalidated properly.

The most common result is the kernel hanging in infinite page fault
loops soon after kexec (usually in schedule_tail, which is usually the
first non-speculative quadrant 0 access to a new PID) due to a stale
PWC. However being a stale translation error, it could result in
anything up to security and data corruption problems.

Fix this by zeroing out PIDR at boot and kexec.

Fixes: 7e381c0f

 ("powerpc/mm/radix: Add mmu context handling callback for radix")
Cc: stable@vger.kernel.org # v4.7+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>