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This patch makes the necessary changes at the x86 architecture
specific layer to enable the use of queued spinlocks for x86-64. As
x86-32 machines are typically not multi-socket. The benefit of queue
spinlock may not be apparent. So queued spinlocks are not enabled.
Currently, there is some incompatibilities between the para-virtualized
spinlock code (which hard-codes the use of ticket spinlock) and the
queued spinlocks. Therefore, the use of queued spinlocks is disabled
when the para-virtualized spinlock is enabled.
The arch/x86/include/asm/qspinlock.h header file includes some x86
specific optimization which will make the queueds spinlock code
perform better than the generic implementation.
Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Daniel J Blueman <daniel@numascale.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Douglas Hatch <doug.hatch@hp.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paolo Bonzini <paolo.bonzini@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1429901803-29771-3-git-send-email-Waiman.Long@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management and ACPI fixes from Rafael Wysocki:
"These include three regression fixes (PCI resources management,
ACPI/PNP device enumeration, ACPI SBS on MacBook) and two ACPI
documentation fixes related to GPIO.
Specifics:
- Fix for a PCI resources management regression introduced during the
4.0 cycle and related to the handling of ACPI resources'
Producer/Consumer flags that turn out to be useless (Jiang Liu)
- Fix for a MacBook regression related to the Smart Battery Subsystem
(SBS) driver causing various problems (stalls on boot, failure to
detect or report battery) to happen and introduced during the 3.18
cycle (Chris Bainbridge)
- Fix for an ACPI/PNP device enumeration regression introduced during
the 3.16 cycle caused by failing to include two PNP device IDs into
the list of IDs that PNP device objects need to be created for
(Witold Szczeponik)
- Fixes for two minor mistakes in the ACPI GPIO properties
documentation (Antonio Ospite, Rafael J Wysocki)"
* tag 'pm+acpi-4.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
ACPI / PNP: add two IDs to list for PNPACPI device enumeration
ACPI / documentation: Fix ambiguity in the GPIO properties document
ACPI / documentation: fix a sentence about GPIO resources
ACPI / SBS: Add 5 us delay to fix SBS hangs on MacBook
x86/PCI/ACPI: Make all resources except [io 0xcf8-0xcff] available on PCI bus
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* acpi-resources:
x86/PCI/ACPI: Make all resources except [io 0xcf8-0xcff] available on PCI bus
* acpi-battery:
ACPI / SBS: Add 5 us delay to fix SBS hangs on MacBook
* acpi-doc:
ACPI / documentation: Fix ambiguity in the GPIO properties document
ACPI / documentation: fix a sentence about GPIO resources
* acpi-pnp:
ACPI / PNP: add two IDs to list for PNPACPI device enumeration
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git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen bug fixes from David Vrabel:
- fix blkback regression if using persistent grants
- fix various event channel related suspend/resume bugs
- fix AMD x86 regression with X86_BUG_SYSRET_SS_ATTRS
- SWIOTLB on ARM now uses frames <4 GiB (if available) so device only
capable of 32-bit DMA work.
* tag 'for-linus-4.1b-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen: Add __GFP_DMA flag when xen_swiotlb_init gets free pages on ARM
hypervisor/x86/xen: Unset X86_BUG_SYSRET_SS_ATTRS on Xen PV guests
xen/events: Set irq_info->evtchn before binding the channel to CPU in __startup_pirq()
xen/console: Update console event channel on resume
xen/xenbus: Update xenbus event channel on resume
xen/events: Clear cpu_evtchn_mask before resuming
xen-pciback: Add name prefix to global 'permissive' variable
xen: Suspend ticks on all CPUs during suspend
xen/grant: introduce func gnttab_unmap_refs_sync()
xen/blkback: safely unmap purge persistent grants
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Ingo Molnar:
"EFI fixes, and FPU fix, a ticket spinlock boundary condition fix and
two build fixes"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/fpu: Always restore_xinit_state() when use_eager_cpu()
x86: Make cpu_tss available to external modules
efi: Fix error handling in add_sysfs_runtime_map_entry()
x86/spinlocks: Fix regression in spinlock contention detection
x86/mm: Clean up types in xlate_dev_mem_ptr()
x86/efi: Store upper bits of command line buffer address in ext_cmd_line_ptr
efivarfs: Ensure VariableName is NUL-terminated
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Ingo Molnar:
"Mostly tooling fixes, but also an uncore PMU driver fix and an uncore
PMU driver hardware-enablement addition"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf probe: Fix segfault if passed with ''.
perf report: Fix -T/--threads option to work again
perf bench numa: Fix immediate meeting of convergence condition
perf bench numa: Fixes of --quiet argument
perf bench futex: Fix hung wakeup tasks after requeueing
perf probe: Fix bug with global variables handling
perf top: Fix a segfault when kernel map is restricted.
tools lib traceevent: Fix build failure on 32-bit arch
perf kmem: Fix compiles on RHEL6/OL6
tools lib api: Undefine _FORTIFY_SOURCE before setting it
perf kmem: Consistently use PRIu64 for printing u64 values
perf trace: Disable events and drain events when forked workload ends
perf trace: Enable events when doing system wide tracing and starting a workload
perf/x86/intel/uncore: Move PCI IDs for IMC to uncore driver
perf/x86/intel/uncore: Add support for Intel Haswell ULT (lower power Mobile Processor) IMC uncore PMUs
perf/x86/intel: Add cpu_(prepare|starting|dying) for core_pmu
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Make sure that xen_swiotlb_init allocates buffers that are DMA capable
when at least one memblock is available below 4G. Otherwise we assume
that all devices on the SoC can cope with >4G addresses. We do this on
ARM and ARM64, where dom0 is mapped 1:1, so pfn == mfn in this case.
No functional changes on x86.
From: Chen Baozi <baozich@gmail.com>
Signed-off-by: Chen Baozi <baozich@gmail.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Tested-by: Chen Baozi <baozich@gmail.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
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The following commit:
f893959b0898 ("x86/fpu: Don't abuse drop_init_fpu() in flush_thread()")
removed drop_init_fpu() usage from flush_thread(). This seems to break
things for me - the Go 1.4 test suite fails all over the place with
floating point comparision errors (offending commit found through
bisection).
The functional change was that flush_thread() after this commit
only calls restore_init_xstate() when both use_eager_fpu() and
!used_math() are true. drop_init_fpu() (now fpu_reset_state()) calls
restore_init_xstate() regardless of whether current used_math() - apply
the same logic here.
Switch used_math() -> tsk_used_math(tsk) to consistently use the grabbed
tsk instead of current, like in the rest of flush_thread().
Tested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Bobby Powers <bobbypowers@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pekka Riikonen <priikone@iki.fi>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: f893959b ("x86/fpu: Don't abuse drop_init_fpu() in flush_thread()")
Link: http://lkml.kernel.org/r/1430147441-9820-1-git-send-email-bobbypowers@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/mfleming/efi into x86/urgent
Pull EFI fixes from Matt Fleming:
* Avoid garbage names in efivarfs due to buggy firmware by zeroing
EFI variable name. (Ross Lagerwall)
* Stop erroneously dropping upper 32 bits of boot command line pointer
in EFI boot stub and stash them in ext_cmd_line_ptr. (Roy Franz)
* Fix double-free bug in error handling code path of EFI runtime map
code. (Dan Carpenter)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Commit 75182b1632 ("x86/asm/entry: Switch all C consumers of
kernel_stack to this_cpu_sp0()") changed current_thread_info
to use this_cpu_sp0, and indirectly made it rely on init_tss
which was exported with EXPORT_PER_CPU_SYMBOL_GPL.
As a result some macros and inline functions such as set/get_fs,
test_thread_flag and variants have been made unusable for
external modules.
Make cpu_tss exported with EXPORT_PER_CPU_SYMBOL so that these
functions are accessible again, as they were previously.
Signed-off-by: Marc Dionne <marc.dionne@your-file-system.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/1430763404-21221-1-git-send-email-marc.dionne@your-file-system.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Commit 61f01dd941ba ("x86_64, asm: Work around AMD SYSRET SS descriptor
attribute issue") makes AMD processors set SS to __KERNEL_DS in
__switch_to() to deal with cases when SS is NULL.
This breaks Xen PV guests who do not want to load SS with__KERNEL_DS.
Since the problem that the commit is trying to address would have to be
fixed in the hypervisor (if it in fact exists under Xen) there is no
reason to set X86_BUG_SYSRET_SS_ATTRS flag for PV VPCUs here.
This can be easily achieved by adding x86_hyper_xen_hvm.set_cpu_features
op which will clear this flag. (And since this structure is no longer
HVM-specific we should do some renaming).
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
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A spinlock is regarded as contended when there is at least one waiter.
Currently, the code that checks whether there are any waiters rely on
tail value being greater than head. However, this is not true if tail
reaches the max value and wraps back to zero, so arch_spin_is_contended()
incorrectly returns 0 (not contended) when tail is smaller than head.
The original code (before regression) handled this case by casting the
(tail - head) to an unsigned value. This change simply restores that
behavior.
Fixes: d6abfdb20223 ("x86/spinlocks/paravirt: Fix memory corruption on unlock")
Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Cc: peterz@infradead.org
Cc: Waiman.Long@hp.com
Cc: borntraeger@de.ibm.com
Cc: oleg@redhat.com
Cc: raghavendra.kt@linux.vnet.ibm.com
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1430799331-20445-1-git-send-email-tahsin@google.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux
Pull powerpc fixes from Michael Ellerman:
- build fix for SMP=n in book3s_xics.c
- fix for Daniel's pci_controller_ops on powernv.
- revert the TM syscall abort patch for now.
- CPU affinity fix from Nathan.
- two EEH fixes from Gavin.
- fix for CR corruption from Sam.
- selftest build fix.
* tag 'powerpc-4.1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux:
powerpc/powernv: Restore non-volatile CRs after nap
powerpc/eeh: Delay probing EEH device during hotplug
powerpc/eeh: Fix race condition in pcibios_set_pcie_reset_state()
powerpc/pseries: Correct cpu affinity for dlpar added cpus
selftests/powerpc: Fix the pmu install rule
Revert "powerpc/tm: Abort syscalls in active transactions"
powerpc/powernv: Fix early pci_controller_ops loading.
powerpc/kvm: Fix SMP=n build error in book3s_xics.c
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git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 fixes from Will Deacon:
"Not too much here, but we've addressed a couple of nasty issues in the
dma-mapping code as well as adding the halfword and byte variants of
load_acquire/store_release following on from the CSD locking bug that
you fixed in the core.
- fix perf devicetree warnings at probe time
- fix memory leak in __dma_free()
- ensure DMA buffers are always zeroed
- show IRQ trigger in /proc/interrupts (for parity with ARM)
- implement byte and halfword access for smp_{load_acquire,store_release}"
* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: perf: Fix the pmu node name in warning message
arm64: perf: don't warn about missing interrupt-affinity property for PPIs
arm64: add missing PAGE_ALIGN() to __dma_free()
arm64: dma-mapping: always clear allocated buffers
ARM64: Enable CONFIG_GENERIC_IRQ_SHOW_LEVEL
arm64: add missing data types in smp_load_acquire/smp_store_release
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Patches 7cba160ad "powernv/cpuidle: Redesign idle states management"
and 77b54e9f2 "powernv/powerpc: Add winkle support for offline cpus"
use non-volatile condition registers (cr2, cr3 and cr4) early in the system
reset interrupt handler (system_reset_pSeries()) before it has been determined
if state loss has occurred. If state loss has not occurred, control returns via
the power7_wakeup_noloss() path which does not restore those condition
registers, leaving them corrupted.
Fix this by restoring the condition registers in the power7_wakeup_noloss()
case.
This is apparent when running a KVM guest on hardware that does not
support winkle or sleep and the guest makes use of secondary threads. In
practice this means Power7 machines, though some early unreleased Power8
machines may also be susceptible.
The secondary CPUs are taken off line before the guest is started and
they call pnv_smp_cpu_kill_self(). This checks support for sleep
states (in this case there is no support) and power7_nap() is called.
When the CPU is woken, power7_nap() returns and because the CPU is
still off line, the main while loop executes again. The sleep states
support test is executed again, but because the tested values cannot
have changed, the compiler has optimized the test away and instead we
rely on the result of the first test, which has been left in cr3
and/or cr4. With the result overwritten, the wrong branch is taken and
power7_winkle() is called on a CPU that does not support it, leading
to it stalling.
Fixes: 7cba160ad789 ("powernv/cpuidle: Redesign idle states management")
Fixes: 77b54e9f213f ("powernv/powerpc: Add winkle support for offline cpus")
[mpe: Massage change log a bit more]
Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Commit 1c509148b ("powerpc/eeh: Do probe on pci_dn") probes EEH
devices in early stage, which is reasonable to pSeries platform.
However, it's wrong for PowerNV platform because the PE# isn't
determined until the resources (IO and MMIO) are assigned to
PE in hotplug case. So we have to delay probing EEH devices
for PowerNV platform until the PE# is assigned.
Fixes: ff57b454ddb9 ("powerpc/eeh: Do probe on pci_dn")
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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When asserting reset in pcibios_set_pcie_reset_state(), the PE
is enforced to (hardware) frozen state in order to drop unexpected
PCI transactions (except PCI config read/write) automatically by
hardware during reset, which would cause recursive EEH error.
However, the (software) frozen state EEH_PE_ISOLATED is missed.
When users get 0xFF from PCI config or MMIO read, EEH_PE_ISOLATED
is set in PE state retrival backend. Unfortunately, nobody (the
reset handler or the EEH recovery functinality in host) will clear
EEH_PE_ISOLATED when the PE has been passed through to guest.
The patch sets and clears EEH_PE_ISOLATED properly during reset
in function pcibios_set_pcie_reset_state() to fix the issue.
Fixes: 28158cd ("Enhance pcibios_set_pcie_reset_state()")
Reported-by: Carol L. Soto <clsoto@us.ibm.com>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Tested-by: Carol L. Soto <clsoto@us.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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The incorrect ordering of operations during cpu dlpar add results in invalid
affinity for the cpu being added. The ibm,associativity property in the
device tree is populated with all zeroes for the added cpu which results in
invalid affinity mappings and all cpus appear to belong to node 0.
This occurs because rtas configure-connector is called prior to making the
rtas set-indicator calls. Phyp does not assign affinity information
for a cpu until the rtas set-indicator calls are made to set the isolation
and allocation state.
Correct the order of operations to make the rtas set-indicator
calls (done in dlpar_acquire_drc) before calling rtas configure-connector.
Fixes: 1a8061c46c46 ("powerpc/pseries: Add kernel based CPU DLPAR handling")
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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An IO port or MMIO resource assigned to a PCI host bridge may be
consumed by the host bridge itself or available to its child
bus/devices. The ACPI specification defines a bit (Producer/Consumer)
to tell whether the resource is consumed by the host bridge itself,
but firmware hasn't used that bit consistently, so we can't rely on it.
Before commit 593669c2ac0f ("x86/PCI/ACPI: Use common ACPI resource
interfaces to simplify implementation"), arch/x86/pci/acpi.c ignored
all IO port resources defined by acpi_resource_io and
acpi_resource_fixed_io to filter out IO ports consumed by the host
bridge itself.
Commit 593669c2ac0f ("x86/PCI/ACPI: Use common ACPI resource interfaces
to simplify implementation") started accepting all IO port and MMIO
resources, which caused a regression that IO port resources consumed
by the host bridge itself became available to its child devices.
Then commit 63f1789ec716 ("x86/PCI/ACPI: Ignore resources consumed by
host bridge itself") ignored resources consumed by the host bridge
itself by checking the IORESOURCE_WINDOW flag, which accidently removed
MMIO resources defined by acpi_resource_memory24, acpi_resource_memory32
and acpi_resource_fixed_memory32.
On x86 and IA64 platforms, all IO port and MMIO resources are assumed
to be available to child bus/devices except one special case:
IO port [0xCF8-0xCFF] is consumed by the host bridge itself
to access PCI configuration space.
So explicitly filter out PCI CFG IO ports[0xCF8-0xCFF]. This solution
will also ease the way to consolidate ACPI PCI host bridge common code
from x86, ia64 and ARM64.
Related ACPI table are archived at:
https://bugzilla.kernel.org/show_bug.cgi?id=94221
Related discussions at:
http://patchwork.ozlabs.org/patch/461633/
https://lkml.org/lkml/2015/3/29/304
Fixes: 63f1789ec716 (Ignore resources consumed by host bridge itself)
Reported-by: Bernhard Thaler <bernhard.thaler@wvnet.at>
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: 4.0+ <stable@vger.kernel.org> # 4.0+
Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Pull kvm changes from Paolo Bonzini:
"Remove from guest code the handling of task migration during a pvclock
read; instead use the correct protocol in KVM.
This removes the need for task migration notifiers in core scheduler
code"
[ The scheduler people really hated the migration notifiers, so this was
kind of required - Linus ]
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
x86: pvclock: Really remove the sched notifier for cross-cpu migrations
kvm: x86: fix kvmclock update protocol
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With commit d5efd9cc9cf2 ("arm64: pmu: add support for interrupt-affinity
property"), we print a warning when we find a PMU SPI with a missing
missing interrupt-affinity property in a pmu node. Unfortunately, we
pass the wrong (NULL) device node to of_node_full_name, resulting in
unhelpful messages such as:
hw perfevents: Failed to parse <no-node>/interrupt-affinity[0]
This patch fixes the name to that of the pmu node.
Fixes: d5efd9cc9cf2 (arm64: pmu: add support for interrupt-affinity property)
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
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PPIs are affine by nature, so the interrupt-affinity property is not
used and therefore we shouldn't print a warning in its absence.
Reported-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
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This reverts commit feba40362b11341bee6d8ed58d54b896abbd9f84.
Although the principle of this change is good, the implementation has a
few issues.
Firstly we can sometimes fail to abort a syscall because r12 may have
been clobbered by C code if we went down the virtual CPU accounting
path, or if syscall tracing was enabled.
Secondly we have decided that it is safer to abort the syscall even
earlier in the syscall entry path, so that we avoid the syscall tracing
path when we are transactional.
So that we have time to thoroughly test those changes we have decided to
revert this for this merge window and will merge the fixed version in
the next window.
NB. Rather than reverting the selftest we just drop tm-syscall from
TEST_PROGS so that it's not run by default.
Fixes: feba40362b11 ("powerpc/tm: Abort syscalls in active transactions")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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__dma_alloc() does a PAGE_ALIGN() on the passed in size argument before
doing anything else. __dma_free() does not. And because it doesn't, it is
possible to leak memory should size not be an integer multiple of PAGE_SIZE.
The solution is to add a PAGE_ALIGN() to __dma_free() like is done in
__dma_alloc().
Additionally, this patch removes a redundant PAGE_ALIGN() from
__dma_alloc_coherent(), since __dma_alloc_coherent() can only be called
from __dma_alloc(), which already does a PAGE_ALIGN() before the call.
Cc: stable@vger.kernel.org
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Dean Nelson <dnelson@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
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Commit 77e32c89a711 ("clockevents: Manage device's state separately for
the core") decouples clockevent device's modes from states. With this
change when a Xen guest tries to resume, it won't be calling its
set_mode op which needs to be done on each VCPU in order to make the
hypervisor aware that we are in oneshot mode.
This happens because clockevents_tick_resume() (which is an intermediate
step of resuming ticks on a processor) doesn't call clockevents_set_state()
anymore and because during suspend clockevent devices on all VCPUs (except
for the one doing the suspend) are left in ONESHOT state. As result, during
resume the clockevents state machine will assume that device is already
where it should be and doesn't need to be updated.
To avoid this problem we should suspend ticks on all VCPUs during
suspend.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
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Load the PowerNV platform pci controller ops into pci controllers
after all the operations are loaded into the platform ops struct, not
before.
Otherwise we aren't actually setting the ops properly which can break
IO for some devices.
Fixes: 65ebf4b63 ("powerpc/powernv: Move controller ops from ppc_md to controller_ops")
Reported-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Commit 34cb7954c0aa "Convert ICS mutex lock to spin lock" added an
include of asm/spinlock.h, which does not work in the SMP=n case.
It should instead include linux/spinlock.h
Fixes: 34cb7954c0aa ("KVM: PPC: Book3S HV: Convert ICS mutex lock to spin lock")
Acked-by: Paul Mackerras <paulus@samba.org>
Reviewed-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile
Pull arch/tile bugfix from Chris Metcalf:
"This just fixes a compiler warning from an old bug that only recently
started generating a warning"
* 'stable' of git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile:
tile: properly use node_isset() on a nodemask_t
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git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Martin Schwidefsky:
"One additional new feature for 4.1, a new PRNG based on SHA-512 for
the zcrypt driver.
Two memory management related changes, the page table reallocation for
KVM is removed, and with file ptes gone the encoding of page table
entries is improved.
And three bug fixes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
s390/zcrypt: Introduce new SHA-512 based Pseudo Random Generator.
s390/mm: change swap pte encoding and pgtable cleanup
s390/mm: correct transfer of dirty & young bits in __pmd_to_pte
s390/bpf: add dependency to z196 features
s390/3215: free memory in error path
s390/kvm: remove delayed reallocation of page tables for KVM
kexec: allocate the kexec control page with KEXEC_CONTROL_MEMORY_GFP
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The code accidentally used cpu_isset() previously in one place
(though properly node_isset() elsewhere).
Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
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This reverts commits 0a4e6be9ca17c54817cf814b4b5aa60478c6df27
and 80f7fdb1c7f0f9266421f823964fd1962681f6ce.
The task migration notifier was originally introduced in order to support
the pvclock vsyscall with non-synchronized TSC, but KVM only supports it
with synchronized TSC. Hence, on KVM the race condition is only needed
due to a bad implementation on the host side, and even then it's so rare
that it's mostly theoretical.
As far as KVM is concerned it's possible to fix the host, avoiding the
additional complexity in the vDSO and the (re)introduction of the task
migration notifier.
Xen, on the other hand, hasn't yet implemented vsyscall support at
all, so we do not care about its plans for non-synchronized TSC.
Reported-by: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The kvmclock spec says that the host will increment a version field to
an odd number, then update stuff, then increment it to an even number.
The host is buggy and doesn't do this, and the result is observable
when one vcpu reads another vcpu's kvmclock data.
There's no good way for a guest kernel to keep its vdso from reading
a different vcpu's kvmclock data, but we don't need to care about
changing VCPUs as long as we read a consistent data from kvmclock.
(VCPU can change outside of this loop too, so it doesn't matter if we
return a value not fit for this VCPU.)
Based on a patch by Radim Krčmář.
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Acked-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Buffers allocated by dma_alloc_coherent() are always zeroed on Alpha,
ARM (32bit), MIPS, PowerPC, x86/x86_64 and probably other architectures.
It turned out that some drivers rely on this 'feature'. Allocated buffer
might be also exposed to userspace with dma_mmap() call, so clearing it
is desired from security point of view to avoid exposing random memory
to userspace. This patch unifies dma_alloc_coherent() behavior on ARM64
architecture with other implementations by unconditionally zeroing
allocated buffer.
Cc: <stable@vger.kernel.org> # v3.14+
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
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Since several interrupt controllers including GIC support both edge and
level triggered interrupts, it's useful to provide that information in
/proc/interrupts even on ARM64 similar to ARM and PPC.
This is based on Geert Uytterhoeven's commit 7c07005eea96 ("ARM: 8339/1:
Enable CONFIG_GENERIC_IRQ_SHOW_LEVEL")
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
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Commit 8053871d0f7f ("smp: Fix smp_call_function_single_async()
locking") introduced a call to smp_load_acquire() with a u16 argument,
but we only cared about u32 and u64 types in that function so far.
This resulted in a compiler warning fortunately, pointing at an
uninitialized use. Due to the implementation structure the compiler
misses that bug in the smp_store_release(), though.
Add the u16 and u8 variants using ldarh/stlrh and ldarb/stlrb,
respectively. Together with the compiletime_assert_atomic_type() check
this should cover all cases now.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
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AMD CPUs don't reinitialize the SS descriptor on SYSRET, so SYSRET with
SS == 0 results in an invalid usermode state in which SS is apparently
equal to __USER_DS but causes #SS if used.
Work around the issue by setting SS to __KERNEL_DS __switch_to, thus
ensuring that SYSRET never happens with SS set to NULL.
This was exposed by a recent vDSO cleanup.
Fixes: e7d6eefaaa44 x86/vdso32/syscall.S: Do not load __USER32_DS to %ss
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull fourth vfs update from Al Viro:
"d_inode() annotations from David Howells (sat in for-next since before
the beginning of merge window) + four assorted fixes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
RCU pathwalk breakage when running into a symlink overmounting something
fix I_DIO_WAKEUP definition
direct-io: only inc/dec inode->i_dio_count for file systems
fs/9p: fix readdir()
VFS: assorted d_backing_inode() annotations
VFS: fs/inode.c helpers: d_inode() annotations
VFS: fs/cachefiles: d_backing_inode() annotations
VFS: fs library helpers: d_inode() annotations
VFS: assorted weird filesystems: d_inode() annotations
VFS: normal filesystems (and lustre): d_inode() annotations
VFS: security/: d_inode() annotations
VFS: security/: d_backing_inode() annotations
VFS: net/: d_inode() annotations
VFS: net/unix: d_backing_inode() annotations
VFS: kernel/: d_inode() annotations
VFS: audit: d_backing_inode() annotations
VFS: Fix up some ->d_inode accesses in the chelsio driver
VFS: Cachefiles should perform fs modifications on the top layer only
VFS: AF_UNIX sockets should call mknod on the top layer only
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Pull crypto fixes from Herbert Xu:
"This push fixes a build problem with img-hash under non-standard
configurations and a serious regression with sha512_ssse3 which can
lead to boot failures"
* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
crypto: img-hash - CRYPTO_DEV_IMGTEC_HASH should depend on HAS_DMA
crypto: x86/sha512_ssse3 - fixup for asm function prototype change
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git://git.kernel.org/pub/scm/linux/kernel/git/jesper/cris
Pull arch/cris updates from Jesper Nilsson:
"Some much needed love for the CRIS-port.
There's a bunch of changes this time, giving the CRISv32 port a bit of
modern makeover with device-tree, irq domain and gpiolib support, and
more switchover to generic frameworks.
Some small fixes and removal of the theoretical SMP support brings up
the rear"
* tag 'cris-for-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/jesper/cris:
cris: fix integer overflow in ELF_ET_DYN_BASE
CRISv32: use GENERIC_SCHED_CLOCK
CRISv32: use MMIO clocksource
CRISv32: use generic clockevents
CRIS: use generic headers via Kbuild
CRIS: use generic cmpxchg.h
CRIS: use generic atomic.h
CRIS: use generic atomic bitops
CRISv10: remove redundant macros from system.h
CRIS: remove SMP code
CRISv32: don't enable irqs in INIT_THREAD
CRISv32: handle multiple signals
CRISv32: prevent bogus restarts on sigreturn
CRISv32: don't attempt syscall restart on irq exit
Add binding documentation for CRIS
CRIS: add Axis 88 board device tree
CRISv32: add device tree support
CRISv32: add irq domains support
CRIS: enable GPIOLIB
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git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux
Pull powerpc fixes from Michael Ellerman:
- fix for mm_dec_nr_pmds() from Scott.
- fixes for oopses seen with KVM + THP from Aneesh.
- build fixes from Aneesh & Shreyas.
* tag 'powerpc-4.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux:
powerpc/mm: Fix build error with CONFIG_PPC_TRANSACTIONAL_MEM disabled
powerpc/kvm: Fix ppc64_defconfig + PPC_POWERNV=n build error
powerpc/mm/thp: Return pte address if we find trans_splitting.
powerpc/mm/thp: Make page table walk safe against thp split/collapse
KVM: PPC: Remove page table walk helpers
KVM: PPC: Use READ_ONCE when dereferencing pte_t pointer
powerpc/hugetlb: Call mm_dec_nr_pmds() in hugetlb_free_pmd_range()
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Pull second batch of KVM changes from Paolo Bonzini:
"This mostly includes the PPC changes for 4.1, which this time cover
Book3S HV only (debugging aids, minor performance improvements and
some cleanups). But there are also bug fixes and small cleanups for
ARM, x86 and s390.
The task_migration_notifier revert and real fix is still pending
review, but I'll send it as soon as possible after -rc1"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (29 commits)
KVM: arm/arm64: check IRQ number on userland injection
KVM: arm: irqfd: fix value returned by kvm_irq_map_gsi
KVM: VMX: Preserve host CR4.MCE value while in guest mode.
KVM: PPC: Book3S HV: Use msgsnd for signalling threads on POWER8
KVM: PPC: Book3S HV: Translate kvmhv_commence_exit to C
KVM: PPC: Book3S HV: Streamline guest entry and exit
KVM: PPC: Book3S HV: Use bitmap of active threads rather than count
KVM: PPC: Book3S HV: Use decrementer to wake napping threads
KVM: PPC: Book3S HV: Don't wake thread with no vcpu on guest IPI
KVM: PPC: Book3S HV: Get rid of vcore nap_count and n_woken
KVM: PPC: Book3S HV: Move vcore preemption point up into kvmppc_run_vcpu
KVM: PPC: Book3S HV: Minor cleanups
KVM: PPC: Book3S HV: Simplify handling of VCPUs that need a VPA update
KVM: PPC: Book3S HV: Accumulate timing information for real-mode code
KVM: PPC: Book3S HV: Create debugfs file for each guest's HPT
KVM: PPC: Book3S HV: Add ICP real mode counters
KVM: PPC: Book3S HV: Move virtual mode ICP functions to real-mode
KVM: PPC: Book3S HV: Convert ICS mutex lock to spin lock
KVM: PPC: Book3S HV: Add guest->host real mode completion counters
KVM: PPC: Book3S HV: Add helpers for lock/unlock hpte
...
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Pull slave-dmaengine updates from Vinod Koul:
- new drivers for:
- Ingenic JZ4780 controller
- APM X-Gene controller
- Freescale RaidEngine device
- Renesas USB Controller
- remove device_alloc_chan_resources dummy handlers
- sh driver cleanups for peri peri and related emmc and asoc patches
as well
- fixes and enhancements spread over the drivers
* 'for-linus' of git://git.infradead.org/users/vkoul/slave-dma: (59 commits)
dmaengine: dw: don't prompt for DW_DMAC_CORE
dmaengine: shdmac: avoid unused variable warnings
dmaengine: fix platform_no_drv_owner.cocci warnings
dmaengine: pch_dma: fix memory leak on failure path in pch_dma_probe()
dmaengine: at_xdmac: unlock spin lock before return
dmaengine: xgene: devm_ioremap() returns NULL on error
dmaengine: xgene: buffer overflow in xgene_dma_init_channels()
dmaengine: usb-dmac: Fix dereferencing freed memory 'desc'
dmaengine: sa11x0: report slave capabilities to upper layers
dmaengine: vdma: Fix compilation warnings
dmaengine: fsl_raid: statify fsl_re_chan_probe
dmaengine: Driver support for FSL RaidEngine device.
dmaengine: xgene_dma_init_ring_mngr() can be static
Documentation: dma: Add documentation for the APM X-Gene SoC DMA device DTS binding
arm64: dts: Add APM X-Gene SoC DMA device and DMA clock DTS nodes
dmaengine: Add support for APM X-Gene SoC DMA engine driver
dmaengine: usb-dmac: Add Renesas USB DMA Controller (USB-DMAC) driver
dmaengine: renesas,usb-dmac: Add device tree bindings documentation
dmaengine: edma: fixed wrongly initialized data parameter to the edma callback
dmaengine: ste_dma40: fix implicit conversion
...
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git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux
Pull second batch of devicetree updates from Rob Herring:
"As Grant mentioned in the first devicetree pull request, here is the
2nd batch of DT changes for 4.1. The main remaining item here is the
endianness bindings and related 8250 driver support.
- DT endianness specification bindings
- big-endian 8250 serial support
- DT overlay unittest updates
- various DT doc updates
- compile fixes for OF_IRQ=n"
* tag 'devicetree-for-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux:
frv: add io{read,write}{16,32}be functions
mn10300: add io{read,write}{16,32}be functions
Documentation: DT bindings: add doc for Altera's SoCFPGA platform
of: base: improve of_get_next_child() kernel-doc
Doc: dt: arch_timer: discourage clock-frequency use
of: unittest: overlay: Keep track of created overlays
of/fdt: fix allocation size for device node path
serial: of_serial: Support big-endian register accesses
serial: 8250: Add support for big-endian MMIO accesses
of: Document {little,big,native}-endian bindings
of/fdt: Add endianness helper function for early init code
of: Add helper function to check MMIO register endianness
of/fdt: Remove "reg" data prints from early_init_dt_scan_memory
of: add vendor prefix for Artesyn
of: Add dummy of_irq_to_resource_table() for IRQ_OF=n
of: OF_IRQ should depend on IRQ_DOMAIN
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git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull initial ACPI support for arm64 from Will Deacon:
"This series introduces preliminary ACPI 5.1 support to the arm64
kernel using the "hardware reduced" profile. We don't support any
peripherals yet, so it's fairly limited in scope:
- MEMORY init (UEFI)
- ACPI discovery (RSDP via UEFI)
- CPU init (FADT)
- GIC init (MADT)
- SMP boot (MADT + PSCI)
- ACPI Kconfig options (dependent on EXPERT)
ACPI for arm64 has been in development for a while now and hardware
has been available that can boot with either FDT or ACPI tables. This
has been made possible by both changes to the ACPI spec to cater for
ARM-based machines (known as "hardware-reduced" in ACPI parlance) but
also a Linaro-driven effort to get this supported on top of the Linux
kernel. This pull request is the result of that work.
These changes allow us to initialise the CPUs, interrupt controller,
and timers via ACPI tables, with memory information and cmdline coming
from EFI. We don't support a hybrid ACPI/FDT scheme. Of course,
there is still plenty of work to do (a serial console would be nice!)
but I expect that to happen on a per-driver basis after this core
series has been merged.
Anyway, the diff stat here is fairly horrible, but splitting this up
and merging it via all the different subsystems would have been
extremely painful. Instead, we've got all the relevant Acks in place
and I've not seen anything other than trivial (Kconfig) conflicts in
-next (for completeness, I've included my resolution below). Nearly
half of the insertions fall under Documentation/.
So, we'll see how this goes. Right now, it all depends on EXPERT and
I fully expect people to use FDT by default for the immediate future"
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (31 commits)
ARM64 / ACPI: make acpi_map_gic_cpu_interface() as void function
ARM64 / ACPI: Ignore the return error value of acpi_map_gic_cpu_interface()
ARM64 / ACPI: fix usage of acpi_map_gic_cpu_interface
ARM64: kernel: acpi: honour acpi=force command line parameter
ARM64: kernel: acpi: refactor ACPI tables init and checks
ARM64: kernel: psci: let ACPI probe PSCI version
ARM64: kernel: psci: factor out probe function
ACPI: move arm64 GSI IRQ model to generic GSI IRQ layer
ARM64 / ACPI: Don't unflatten device tree if acpi=force is passed
ARM64 / ACPI: additions of ACPI documentation for arm64
Documentation: ACPI for ARM64
ARM64 / ACPI: Enable ARM64 in Kconfig
XEN / ACPI: Make XEN ACPI depend on X86
ARM64 / ACPI: Select ACPI_REDUCED_HARDWARE_ONLY if ACPI is enabled on ARM64
clocksource / arch_timer: Parse GTDT to initialize arch timer
irqchip: Add GICv2 specific ACPI boot support
ARM64 / ACPI: Introduce ACPI_IRQ_MODEL_GIC and register device's gsi
ACPI / processor: Make it possible to get CPU hardware ID via GICC
ACPI / processor: Introduce phys_cpuid_t for CPU hardware ID
ARM64 / ACPI: Parse MADT for SMP initialization
...
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Pull ARM fixes from Russell King:
"A few fixes for the recently merged development updates:
- the update to convert a code branch in the procinfo structure
forgot to update the nommu code.
- VDSO only supported for V7 CPUs and later.
- VDSO build creates files which should be ignored by git but are not.
- ensure that make arch/arm/vdso/ doesn't build if it isn't enabled"
* 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm:
ARM: 8344/1: VDSO: honor CONFIG_VDSO in Makefile
ARM: 8343/1: VDSO: add build artifacts to .gitignore
ARM: Fix nommu booting
ARM: 8342/1: VDSO: depend on CPU_V7
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Pull arch/nios2 updates from Ley Foon Tan:
- update cache management code
- rework trap handler with new define trap #.
- fix on check header warning.
* tag 'nios2-v4.1-rc1' of git://git.rocketboards.org/linux-socfpga-next:
nios2: rework cache
nios2: Add types.h header required for __u32 type
nios2: rework trap handler
nios2: remove end address checking for initda
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git://git.kernel.org/pub/scm/linux/kernel/git/realmz6/blackfin-linux
Pull blackfin updates from Steven Miao.
* tag 'blackfin-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/realmz6/blackfin-linux:
eth: bf609 eth clock: add pclk clock for stmmac driver probe
blackfin: Wire up missing syscalls
arch: blackfin: kernel: kgdb: Remove unused function
dma: fix build error after update to v3.19
blackfin: io: define __raw_readx/writex with bfin_readx/writex
bf609: add resources for lcd nl8048
pm: sometimes wake up from suspend to RAM would fail
debug-mmrs: Eliminate all traces of the USB_PHY_TEST MMR
bf609: remove softswitch i2c configuration from adv7842 and adv7511 platform data
bf609: add platform data for soft switch devices on the video extenders
bf609: enable soft switch gpio driver by default
bf609: add gpio soft switch platform data for mcp23017 i2c devices
bf609: use new SND_BF6XX_PCM to choose audio pcm driver
bug[220] kgdb: change the smp cross core function entry
arch: blackfin: kernel: setup.c: Cleaning up missing null-terminate in conjunction with strncpy
blackfin: defconfigs: cleanup unused CONFIG_MTD_CHAR, add MTD_SPI_NOR for BF537-STAMP
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git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/metag
Pull Metag architecture updates from James Hogan:
"Just the one change for v4.1-rc1. A minor cleanup of copy_thread()"
* tag 'metag-for-v4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/metag:
metag: copy_thread(): rename 'arg' argument to 'kthread_arg'
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git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc
Pull ARC updates from Vineet Gupta:
- perf fixes/improvements
- misc cleanups
* tag 'arc-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
ARC: perf: don't add code for impossible case
ARC: perf: Rename DT binding to not confuse with power mgmt
ARC: perf: add user space attribution in callchains
ARC: perf: Add kernel callchain support
ARC: perf: support cache hit/miss ratio
ARC: perf: Add some comments/debug stuff
ARC: perf: make @arc_pmu static global
ARC: mem init spring cleaning - No functional changes
ARC: Fix RTT boot printing
ARC: fold __builtin_constant_p() into test_bit()
ARC: rename unhandled exception handler
ARC: cosmetic: Remove unused ECR bitfield masks
ARC: Fix WRITE_BCR
ARC: [nsimosci] Update defconfig
arc: copy_thread(): rename 'arg' argument to 'kthread_arg'
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Commit cae2a173fe94 ("x86: clean up/fix 'copy_in_user()' tail zeroing")
fixed the failure case tail zeroing of one special case of the x86-64
generic user-copy routine, namely when used for the user-to-user case
("copy_in_user()").
But in the process it broke an even more unusual case: using the user
copy routine for kernel-to-kernel copying.
Now, normally kernel-kernel copies are obviously done using memcpy(),
but we have a couple of special cases when we use the user-copy
functions. One is when we pass a kernel buffer to a regular user-buffer
routine, using set_fs(KERNEL_DS). That's a "normal" case, and continued
to work fine, because it never takes any faults (with the possible
exception of a silent and successful vmalloc fault).
But Jan Beulich pointed out another, very unusual, special case: when we
use the user-copy routines not because it's a path that expects a user
pointer, but for a couple of ftrace/kgdb cases that want to do a kernel
copy, but do so using "unsafe" buffers, and use the user-copy routine to
gracefully handle faults. IOW, for probe_kernel_write().
And that broke for the case of a faulting kernel destination, because we
saw the kernel destination and wanted to try to clear the tail of the
buffer. Which doesn't work, since that's what faults.
This only triggers for things like kgdb and ftrace users (eg trying
setting a breakpoint on read-only memory), but it's definitely a bug.
The fix is to not compare against the kernel address start (TASK_SIZE),
but instead use the same limits "access_ok()" uses.
Reported-and-tested-by: Jan Beulich <jbeulich@suse.com>
Cc: stable@vger.kernel.org # 4.0
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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