Global pages are bad for hardening because they potentially let an
exploit read the kernel image via a Meltdown-style attack which
makes it easier to find gadgets.
But, global pages are good for performance because they reduce TLB
misses when making user/kernel transitions, especially when PCIDs
are not available, such as on older hardware, or where a hypervisor
has disabled them for some reason.
This patch implements a basic, sane policy: If you have PCIDs, you
only map a minimal amount of kernel text global. If you do not have
PCIDs, you map all kernel text global.
This policy effectively makes PCIDs something that not only adds
performance but a little bit of hardening as well.
I ran a simple "lseek" microbenchmark[1] to test the benefit on
a modern Atom microserver. Most of the benefit comes from applying
the series before this patch ("entry only"), but there is still a
signifiant benefit from this patch.
No Global Lines (baseline ): 6077741 lseeks/sec
88 Global Lines (entry only): 7528609 lseeks/sec (+23.9%)
94 Global Lines (this patch): 8433111 lseeks/sec (+38.8%)
[1.] https://github.com/antonblanchard/will-it-scale/blob/master/tests/lseek1.c
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180406205518.E3D989EB@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A PTE is constructed from a physical address and a pgprotval_t.
__PAGE_KERNEL, for instance, is a pgprot_t and must be converted
into a pgprotval_t before it can be used to create a PTE. This is
done implicitly within functions like pfn_pte() by massage_pgprot().
However, this makes it very challenging to set bits (and keep them
set) if your bit is being filtered out by massage_pgprot().
This moves the bit filtering out of pfn_pte() and friends. For
users of PAGE_KERNEL*, filtering will be done automatically inside
those macros but for users of __PAGE_KERNEL*, they need to do their
own filtering now.
Note that we also just move pfn_pte/pmd/pud() over to check_pgprot()
instead of massage_pgprot(). This way, we still *look* for
unsupported bits and properly warn about them if we find them. This
might happen if an unfiltered __PAGE_KERNEL* value was passed in,
for instance.
- printk format warning fix from: Arnd Bergmann <arnd@arndb.de>
- boot crash fix from: Tom Lendacky <thomas.lendacky@amd.com>
- crash bisected by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reported-and-fixed-by: Arnd Bergmann <arnd@arndb.de>
Fixed-by: Tom Lendacky <thomas.lendacky@amd.com>
Bisected-by: Mike Galbraith <efault@gmx.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180406205509.77E1D7F6@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The __PAGE_KERNEL_* page permissions are "raw". They contain bits
that may or may not be supported on the current processor. They need
to be filtered by a mask (currently __supported_pte_mask) to turn them
into a value that we can actually set in a PTE.
These __PAGE_KERNEL_* values all contain _PAGE_GLOBAL. But, with PTI,
we want to be able to support _PAGE_GLOBAL (have the bit set in
__supported_pte_mask) but not have it appear in any of these masks by
default.
This patch creates a new mask, __default_kernel_pte_mask, and applies
it when creating all of the PAGE_KERNEL_* masks. This makes
PAGE_KERNEL_* safe to use anywhere (they only contain supported bits).
It also ensures that PAGE_KERNEL_* contains _PAGE_GLOBAL on PTI=n
kernels but clears _PAGE_GLOBAL when PTI=y.
We also make __default_kernel_pte_mask a non-GPL exported symbol
because there are plenty of driver-available interfaces that take
PAGE_KERNEL_* permissions.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180406205506.030DB6B6@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Consistently use types provided by <linux/types.h> to fix the following
asm/bootparam.h userspace compilation errors:
/usr/include/asm/bootparam.h:140:2: error: unknown type name 'u16'
u16 version;
/usr/include/asm/bootparam.h:141:2: error: unknown type name 'u16'
u16 compatible_version;
/usr/include/asm/bootparam.h:142:2: error: unknown type name 'u16'
u16 pm_timer_address;
/usr/include/asm/bootparam.h:143:2: error: unknown type name 'u16'
u16 num_cpus;
/usr/include/asm/bootparam.h:144:2: error: unknown type name 'u64'
u64 pci_mmconfig_base;
/usr/include/asm/bootparam.h:145:2: error: unknown type name 'u32'
u32 tsc_khz;
/usr/include/asm/bootparam.h:146:2: error: unknown type name 'u32'
u32 apic_khz;
/usr/include/asm/bootparam.h:147:2: error: unknown type name 'u8'
u8 standard_ioapic;
/usr/include/asm/bootparam.h:148:2: error: unknown type name 'u8'
u8 cpu_ids[255];
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Acked-by: Jan Kiszka <jan.kiszka@siemens.com>
Cc: <stable@vger.kernel.org> # v4.16
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 4a362601ba ("x86/jailhouse: Add infrastructure for running in non-root cell")
Link: http://lkml.kernel.org/r/20180405043210.GA13254@altlinux.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull EFI updates from Ingo Molnar:
"The main EFI changes in this cycle were:
- Fix the apple-properties code (Andy Shevchenko)
- Add WARN() on arm64 if UEFI Runtime Services corrupt the reserved
x18 register (Ard Biesheuvel)
- Use efi_switch_mm() on x86 instead of manipulating %cr3 directly
(Sai Praneeth)
- Fix early memremap leak in ESRT code (Ard Biesheuvel)
- Switch to L"xxx" notation for wide string literals (Ard Biesheuvel)
- ... plus misc other cleanups and bugfixes"
* 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/efi: Use efi_switch_mm() rather than manually twiddling with %cr3
x86/efi: Replace efi_pgd with efi_mm.pgd
efi: Use string literals for efi_char16_t variable initializers
efi/esrt: Fix handling of early ESRT table mapping
efi: Use efi_mm in x86 as well as ARM
efi: Make const array 'apple' static
efi/apple-properties: Use memremap() instead of ioremap()
efi: Reorder pr_notice() with add_device_randomness() call
x86/efi: Replace GFP_ATOMIC with GFP_KERNEL in efi_query_variable_store()
efi/arm64: Check whether x18 is preserved by runtime services calls
efi/arm*: Stop printing addresses of virtual mappings
efi/apple-properties: Remove redundant attribute initialization from unmarshal_key_value_pairs()
efi/arm*: Only register page tables when they exist
Pull x86 dma mapping updates from Ingo Molnar:
"This tree, by Christoph Hellwig, switches over the x86 architecture to
the generic dma-direct and swiotlb code, and also unifies more of the
dma-direct code between architectures. The now unused x86-only
primitives are removed"
* 'x86-dma-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
dma-mapping: Don't clear GFP_ZERO in dma_alloc_attrs
swiotlb: Make swiotlb_{alloc,free}_buffer depend on CONFIG_DMA_DIRECT_OPS
dma/swiotlb: Remove swiotlb_{alloc,free}_coherent()
dma/direct: Handle force decryption for DMA coherent buffers in common code
dma/direct: Handle the memory encryption bit in common code
dma/swiotlb: Remove swiotlb_set_mem_attributes()
set_memory.h: Provide set_memory_{en,de}crypted() stubs
x86/dma: Remove dma_alloc_coherent_gfp_flags()
iommu/intel-iommu: Enable CONFIG_DMA_DIRECT_OPS=y and clean up intel_{alloc,free}_coherent()
iommu/amd_iommu: Use CONFIG_DMA_DIRECT_OPS=y and dma_direct_{alloc,free}()
x86/dma/amd_gart: Use dma_direct_{alloc,free}()
x86/dma/amd_gart: Look at dev->coherent_dma_mask instead of GFP_DMA
x86/dma: Use generic swiotlb_ops
x86/dma: Use DMA-direct (CONFIG_DMA_DIRECT_OPS=y)
x86/dma: Remove dma_alloc_coherent_mask()
Pull x86 timer updates from Ingo Molnar:
"Two changes: add the new convert_art_ns_to_tsc() API for upcoming
Intel Goldmont+ drivers, and remove the obsolete rdtscll() API"
* 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/tsc: Get rid of rdtscll()
x86/tsc: Convert ART in nanoseconds to TSC
Pull x86 platform updates from Ingo Molnar:
"The main changes in this cycle were:
- Add "Jailhouse" hypervisor support (Jan Kiszka)
- Update DeviceTree support (Ivan Gorinov)
- Improve DMI date handling (Andy Shevchenko)"
* 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/PCI: Fix a potential regression when using dmi_get_bios_year()
firmware/dmi_scan: Uninline dmi_get_bios_year() helper
x86/devicetree: Use CPU description from Device Tree
of/Documentation: Specify local APIC ID in "reg"
MAINTAINERS: Add entry for Jailhouse
x86/jailhouse: Allow to use PCI_MMCONFIG without ACPI
x86: Consolidate PCI_MMCONFIG configs
x86: Align x86_64 PCI_MMCONFIG with 32-bit variant
x86/jailhouse: Enable PCI mmconfig access in inmates
PCI: Scan all functions when running over Jailhouse
jailhouse: Provide detection for non-x86 systems
x86/devicetree: Fix device IRQ settings in DT
x86/devicetree: Initialize device tree before using it
pci: Simplify code by using the new dmi_get_bios_year() helper
ACPI/sleep: Simplify code by using the new dmi_get_bios_year() helper
x86/pci: Simplify code by using the new dmi_get_bios_year() helper
dmi: Introduce the dmi_get_bios_year() helper function
x86/platform/quark: Re-use DEFINE_SHOW_ATTRIBUTE() macro
x86/platform/atom: Re-use DEFINE_SHOW_ATTRIBUTE() macro
Pull x86 mm updates from Ingo Molnar:
- Extend the memmap= boot parameter syntax to allow the redeclaration
and dropping of existing ranges, and to support all e820 range types
(Jan H. Schönherr)
- Improve the W+X boot time security checks to remove false positive
warnings on Xen (Jan Beulich)
- Support booting as Xen PVH guest (Juergen Gross)
- Improved 5-level paging (LA57) support, in particular it's possible
now to have a single kernel image for both 4-level and 5-level
hardware (Kirill A. Shutemov)
- AMD hardware RAM encryption support (SME/SEV) fixes (Tom Lendacky)
- Preparatory commits for hardware-encrypted RAM support on Intel CPUs.
(Kirill A. Shutemov)
- Improved Intel-MID support (Andy Shevchenko)
- Show EFI page tables in page_tables debug files (Andy Lutomirski)
- ... plus misc fixes and smaller cleanups
* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (56 commits)
x86/cpu/tme: Fix spelling: "configuation" -> "configuration"
x86/boot: Fix SEV boot failure from change to __PHYSICAL_MASK_SHIFT
x86/mm: Update comment in detect_tme() regarding x86_phys_bits
x86/mm/32: Remove unused node_memmap_size_bytes() & CONFIG_NEED_NODE_MEMMAP_SIZE logic
x86/mm: Remove pointless checks in vmalloc_fault
x86/platform/intel-mid: Add special handling for ACPI HW reduced platforms
ACPI, x86/boot: Introduce the ->reduced_hw_early_init() ACPI callback
ACPI, x86/boot: Split out acpi_generic_reduce_hw_init() and export
x86/pconfig: Provide defines and helper to run MKTME_KEY_PROG leaf
x86/pconfig: Detect PCONFIG targets
x86/tme: Detect if TME and MKTME is activated by BIOS
x86/boot/compressed/64: Handle 5-level paging boot if kernel is above 4G
x86/boot/compressed/64: Use page table in trampoline memory
x86/boot/compressed/64: Use stack from trampoline memory
x86/boot/compressed/64: Make sure we have a 32-bit code segment
x86/mm: Do not use paravirtualized calls in native_set_p4d()
kdump, vmcoreinfo: Export pgtable_l5_enabled value
x86/boot/compressed/64: Prepare new top-level page table for trampoline
x86/boot/compressed/64: Set up trampoline memory
x86/boot/compressed/64: Save and restore trampoline memory
...
Pull x86 cleanups and msr updates from Ingo Molnar:
"The main change is a performance/latency improvement to /dev/msr
access. The rest are misc cleanups"
* 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/msr: Make rdmsrl_safe_on_cpu() scheduling safe as well
x86/cpuid: Allow cpuid_read() to schedule
x86/msr: Allow rdmsr_safe_on_cpu() to schedule
x86/rtc: Stop using deprecated functions
x86/dumpstack: Unify show_regs()
x86/fault: Do not print IP in show_fault_oops()
x86/MSR: Move native_* variants to msr.h
Pull x86 build updates from Ingo Molnar:
"The biggest change is the forcing of asm-goto support on x86, which
effectively increases the GCC minimum supported version to gcc-4.5 (on
x86)"
* 'x86-build-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/build: Don't pass in -D__KERNEL__ multiple times
x86: Remove FAST_FEATURE_TESTS
x86: Force asm-goto
x86/build: Drop superfluous ALIGN from the linker script
Pull x86 asm fixlets from Ingo Molnar:
"A clobber list fix and cleanups"
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/asm: Trim clear_page.S includes
x86/asm: Clobber flags in clear_page()
Pull x86 apic updates from Ingo Molnar:
"The main x86 APIC/IOAPIC changes in this cycle were:
- Robustify kexec support to more carefully restore IRQ hardware
state before calling into kexec/kdump kernels. (Baoquan He)
- Clean up the local APIC code a bit (Dou Liyang)
- Remove unused callbacks (David Rientjes)"
* 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/apic: Finish removing unused callbacks
x86/apic: Drop logical_smp_processor_id() inline
x86/apic: Modernize the pending interrupt code
x86/apic: Move pending interrupt check code into it's own function
x86/apic: Set up through-local-APIC mode on the boot CPU if 'noapic' specified
x86/apic: Rename variables and functions related to x86_io_apic_ops
x86/apic: Remove the (now) unused disable_IO_APIC() function
x86/apic: Fix restoring boot IRQ mode in reboot and kexec/kdump
x86/apic: Split disable_IO_APIC() into two functions to fix CONFIG_KEXEC_JUMP=y
x86/apic: Split out restore_boot_irq_mode() from disable_IO_APIC()
x86/apic: Make setup_local_APIC() static
x86/apic: Simplify init_bsp_APIC() usage
x86/x2apic: Mark set_x2apic_phys_mode() as __init
Pull x86 RAS updates from Ingo Molnar:
"The main changes in this cycle were:
- AMD MCE support/decoding improvements (Yazen Ghannam)
- general MCE header cleanups and reorganization (Borislav Petkov)"
* 'ras-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
Revert "x86/mce/AMD: Collect error info even if valid bits are not set"
x86/MCE: Cleanup and complete struct mce fields definitions
x86/mce/AMD: Carve out SMCA get_block_address() code
x86/mce/AMD: Get address from already initialized block
x86/mce/AMD, EDAC/mce_amd: Enumerate Reserved SMCA bank type
x86/mce/AMD: Pass the bank number to smca_get_bank_type()
x86/mce/AMD: Collect error info even if valid bits are not set
x86/mce: Issue the 'mcelog --ascii' message only on !AMD
x86/mce: Convert 'struct mca_config' bools to a bitfield
x86/mce: Put private structures and definitions into the internal header
Pull perf updates from Ingo Molnar:
"The main kernel side changes were:
- Modernize the kprobe and uprobe creation/destruction tooling ABIs:
The existing text based APIs (kprobe_events and uprobe_events in
tracefs), are naive, limited ABIs in that they require user-space
to clean up after themselves, which is both difficult and fragile
if the tool is buggy or exits unexpectedly. In other words they are
not really suited for modern, robust tooling.
So introduce a modern, file descriptor based ABI that does not have
these limitations: introduce the 'perf_kprobe' and 'perf_uprobe'
PMUs and extend the perf_event_open() syscall to create events with
a kprobe/uprobe attached to them. These [k,u]probe are associated
with this file descriptor, so they are not available in tracefs.
(Song Liu)
- Intel Cannon Lake CPU support (Harry Pan)
- Intel PT cleanups (Alexander Shishkin)
- Improve the performance of pinned/flexible event groups by using RB
trees (Alexey Budankov)
- Add PERF_EVENT_IOC_MODIFY_ATTRIBUTES which allows the modification
of hardware breakpoints, which new ABI variant massively speeds up
existing tooling that uses hardware breakpoints to instrument (and
debug) memory usage.
(Milind Chabbi, Jiri Olsa)
- Various Intel PEBS handling fixes and improvements, and other Intel
PMU improvements (Kan Liang)
- Various perf core improvements and optimizations (Peter Zijlstra)
- ... misc cleanups, fixes and updates.
There's over 200 tooling commits, here's an (imperfect) list of
highlights:
- 'perf annotate' improvements:
* Recognize and handle jumps to other functions as calls, which
improves the navigation along jumps and back. (Arnaldo Carvalho
de Melo)
* Add the 'P' hotkey in TUI annotation to dump annotation output
into a file, to ease e-mail reporting of annotation details.
(Arnaldo Carvalho de Melo)
* Add an IPC/cycles column to the TUI (Jin Yao)
* Improve s390 assembly annotation (Thomas Richter)
* Refactor the output formatting logic to better separate it into
interactive and non-interactive features and add the --stdio2
output variant to demonstrate this. (Arnaldo Carvalho de Melo)
- 'perf script' improvements:
* Add Python 3 support (Jaroslav Škarvada)
* Add --show-round-event (Jiri Olsa)
- 'perf c2c' improvements:
* Add NUMA analysis support (Jiri Olsa)
- 'perf trace' improvements:
* Improve PowerPC support (Ravi Bangoria)
- 'perf inject' improvements:
* Integrate ARM CoreSight traces (Robert Walker)
- 'perf stat' improvements:
* Add the --interval-count option (yuzhoujian)
* Add the --timeout option (yuzhoujian)
- 'perf sched' improvements (Changbin Du)
- Vendor events improvements :
* Add IBM s390 vendor events (Thomas Richter)
* Add and improve arm64 vendor events (John Garry, Ganapatrao
Kulkarni)
* Update POWER9 vendor events (Sukadev Bhattiprolu)
- Intel PT tooling improvements (Adrian Hunter)
- PMU handling improvements (Agustin Vega-Frias)
- Record machine topology in perf.data (Jiri Olsa)
- Various overwrite related cleanups (Kan Liang)
- Add arm64 dwarf post unwind support (Kim Phillips, Jean Pihet)
- ... and lots of other changes, cleanups and fixes, see the shortlog
and Git history for details"
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (262 commits)
perf/x86/intel: Enable C-state residency events for Cannon Lake
perf/x86/intel: Add Cannon Lake support for RAPL profiling
perf/x86/pt, coresight: Clean up address filter structure
perf vendor events s390: Add JSON files for IBM z14
perf vendor events s390: Add JSON files for IBM z13
perf vendor events s390: Add JSON files for IBM zEC12 zBC12
perf vendor events s390: Add JSON files for IBM z196
perf vendor events s390: Add JSON files for IBM z10EC z10BC
perf mmap: Be consistent when checking for an unmaped ring buffer
perf mmap: Fix accessing unmapped mmap in perf_mmap__read_done()
perf build: Fix check-headers.sh opts assignment
perf/x86: Update rdpmc_always_available static key to the modern API
perf annotate: Use absolute addresses to calculate jump target offsets
perf annotate: Defer searching for comma in raw line till it is needed
perf annotate: Support jumping from one function to another
perf annotate: Add "_local" to jump/offset validation routines
perf python: Reference Py_None before returning it
perf annotate: Mark jumps to outher functions with the call arrow
perf annotate: Pass function descriptor to its instruction parsing routines
perf annotate: No need to calculate notes->start twice
...
Pull locking updates from Ingo Molnar:
"The main changes in the locking subsystem in this cycle were:
- Add the Linux Kernel Memory Consistency Model (LKMM) subsystem,
which is an an array of tools in tools/memory-model/ that formally
describe the Linux memory coherency model (a.k.a.
Documentation/memory-barriers.txt), and also produce 'litmus tests'
in form of kernel code which can be directly executed and tested.
Here's a high level background article about an earlier version of
this work on LWN.net:
https://lwn.net/Articles/718628/
The design principles:
"There is reason to believe that Documentation/memory-barriers.txt
could use some help, and a major purpose of this patch is to
provide that help in the form of a design-time tool that can
produce all valid executions of a small fragment of concurrent
Linux-kernel code, which is called a "litmus test". This tool's
functionality is roughly similar to a full state-space search.
Please note that this is a design-time tool, not useful for
regression testing. However, we hope that the underlying
Linux-kernel memory model will be incorporated into other tools
capable of analyzing large bodies of code for regression-testing
purposes."
[...]
"A second tool is klitmus7, which converts litmus tests to
loadable kernel modules for direct testing. As with herd7, the
klitmus7 code is freely available from
http://diy.inria.fr/sources/index.html
(and via "git" at https://github.com/herd/herdtools7)"
[...]
Credits go to:
"This patch was the result of a most excellent collaboration
founded by Jade Alglave and also including Alan Stern, Andrea
Parri, and Luc Maranget."
... and to the gents listed in the MAINTAINERS entry:
LINUX KERNEL MEMORY CONSISTENCY MODEL (LKMM)
M: Alan Stern <stern@rowland.harvard.edu>
M: Andrea Parri <parri.andrea@gmail.com>
M: Will Deacon <will.deacon@arm.com>
M: Peter Zijlstra <peterz@infradead.org>
M: Boqun Feng <boqun.feng@gmail.com>
M: Nicholas Piggin <npiggin@gmail.com>
M: David Howells <dhowells@redhat.com>
M: Jade Alglave <j.alglave@ucl.ac.uk>
M: Luc Maranget <luc.maranget@inria.fr>
M: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
The LKMM project already found several bugs in Linux locking
primitives and improved the understanding and the documentation of
the Linux memory model all around.
- Add KASAN instrumentation to atomic APIs (Dmitry Vyukov)
- Add RWSEM API debugging and reorganize the lock debugging Kconfig
(Waiman Long)
- ... misc cleanups and other smaller changes"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (31 commits)
locking/Kconfig: Restructure the lock debugging menu
locking/Kconfig: Add LOCK_DEBUGGING_SUPPORT to make it more readable
locking/rwsem: Add DEBUG_RWSEMS to look for lock/unlock mismatches
lockdep: Make the lock debug output more useful
locking/rtmutex: Handle non enqueued waiters gracefully in remove_waiter()
locking/atomic, asm-generic, x86: Add comments for atomic instrumentation
locking/atomic, asm-generic: Add KASAN instrumentation to atomic operations
locking/atomic/x86: Switch atomic.h to use atomic-instrumented.h
locking/atomic, asm-generic: Add asm-generic/atomic-instrumented.h
locking/xchg/alpha: Remove superfluous memory barriers from the _local() variants
tools/memory-model: Finish the removal of rb-dep, smp_read_barrier_depends(), and lockless_dereference()
tools/memory-model: Add documentation of new litmus test
tools/memory-model: Remove mention of docker/gentoo image
locking/memory-barriers: De-emphasize smp_read_barrier_depends() some more
locking/lockdep: Show unadorned pointers
mutex: Drop linkage.h from mutex.h
tools/memory-model: Remove rb-dep, smp_read_barrier_depends, and lockless_dereference
tools/memory-model: Convert underscores to hyphens
tools/memory-model: Add a S lock-based external-view litmus test
tools/memory-model: Add required herd7 version to README file
...
Pull x86 PTI fixes from Ingo Molnar:
"Two fixes: a relatively simple objtool fix that makes Clang built
kernels work with ORC debug info, plus an alternatives macro fix"
* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/alternatives: Fixup alternative_call_2
objtool: Add Clang support
A critical error was found testing the fixed UV4 HUB in that an MMR address
was found to be incorrect. This causes the virtual address space for
accessing the MMIOH1 region to be allocated with the incorrect size.
Fixes: 673aa20c55 ("x86/platform/UV: Update uv_mmrs.h to prepare for UV4A fixes")
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Cc: Russ Anderson <russ.anderson@hpe.com>
Cc: Andrew Banman <andrew.banman@hpe.com>
Link: https://lkml.kernel.org/r/20180328174011.041801248@stormcage.americas.sgi.com
BAU uses the old alloc_initr_gate90 method to setup its interrupt. This
fails silently as the BAU vector is in the range of APIC vectors that are
registered to the spurious interrupt handler. As a consequence BAU
broadcasts are not handled, and the broadcast source CPU hangs.
Update BAU to use new idt structure.
Fixes: dc20b2d526 ("x86/idt: Move interrupt gate initialization to IDT code")
Signed-off-by: Andrew Banman <abanman@hpe.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Mike Travis <mike.travis@hpe.com>
Cc: Dimitri Sivanich <sivanich@hpe.com>
Cc: Russ Anderson <rja@hpe.com>
Cc: stable@vger.kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: https://lkml.kernel.org/r/1522188546-196177-1-git-send-email-abanman@hpe.com
The following pattern fails to compile while the same pattern
with alternative_call() does:
if (...)
alternative_call_2(...);
else
alternative_call_2(...);
as it expands into
if (...)
{
}; <===
else
{
};
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20180114120504.GA11368@avx2
Pull x86 and PTI fixes from Ingo Molnar:
"Misc fixes:
- fix EFI pagetables freeing
- fix vsyscall pagetable setting on Xen PV guests
- remove ancient CONFIG_X86_PPRO_FENCE=y - x86 is TSO again
- fix two binutils (ld) development version related incompatibilities
- clean up breakpoint handling
- fix an x86 self-test"
* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/entry/64: Don't use IST entry for #BP stack
x86/efi: Free efi_pgd with free_pages()
x86/vsyscall/64: Use proper accessor to update P4D entry
x86/cpu: Remove the CONFIG_X86_PPRO_FENCE=y quirk
x86/boot/64: Verify alignment of the LOAD segment
x86/build/64: Force the linker to use 2MB page size
selftests/x86/ptrace_syscall: Fix for yet more glibc interference
Commit 99770737ca ("x86/asm/tsc: Add rdtscll() merge helper") added
rdtscll() in August 2015 along with the comment:
/* Deprecated, keep it for a cycle for easier merging: */
12 cycles later it's really overdue for removal.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The undocumented 'icebp' instruction (aka 'int1') works pretty much like
'int3' in the absense of in-circuit probing equipment (except,
obviously, that it raises #DB instead of raising #BP), and is used by
some validation test-suites as such.
But Andy Lutomirski noticed that his test suite acted differently in kvm
than on bare hardware.
The reason is that kvm used an inexact test for the icebp instruction:
it just assumed that an all-zero VM exit qualification value meant that
the VM exit was due to icebp.
That is not unlike the guess that do_debug() does for the actual
exception handling case, but it's purely a heuristic, not an absolute
rule. do_debug() does it because it wants to ascribe _some_ reasons to
the #DB that happened, and an empty %dr6 value means that 'icebp' is the
most likely casue and we have no better information.
But kvm can just do it right, because unlike the do_debug() case, kvm
actually sees the real reason for the #DB in the VM-exit interruption
information field.
So instead of relying on an inexact heuristic, just use the actual VM
exit information that says "it was 'icebp'".
Right now the 'icebp' instruction isn't technically documented by Intel,
but that will hopefully change. The special "privileged software
exception" information _is_ actually mentioned in the Intel SDM, even
though the cause of it isn't enumerated.
Reported-by: Andy Lutomirski <luto@kernel.org>
Tested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Give the basic phys_to_dma() and dma_to_phys() helpers a __-prefix and add
the memory encryption mask to the non-prefixed versions. Use the
__-prefixed versions directly instead of clearing the mask again in
various places.
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jon Mason <jdmason@kudzu.us>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Muli Ben-Yehuda <mulix@mulix.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: iommu@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/20180319103826.12853-13-hch@lst.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that set_memory_decrypted() is always available we can just call it
directly.
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jon Mason <jdmason@kudzu.us>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Muli Ben-Yehuda <mulix@mulix.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: iommu@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/20180319103826.12853-12-hch@lst.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
All dma_ops implementations used on x86 now take care of setting their own
required GFP_ masks for the allocation. And given that the common code
now clears harmful flags itself that means we can stop the flags in all
the IOMMU implementations as well.
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jon Mason <jdmason@kudzu.us>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Muli Ben-Yehuda <mulix@mulix.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: iommu@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/20180319103826.12853-10-hch@lst.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The generic swiotlb DMA ops were based on the x86 ones and provide
equivalent functionality, so use them.
Also fix the sta2x11 case. For that SOC the DMA map ops need an
additional physical to DMA address translations. For swiotlb buffers
that is done throught the phys_to_dma helper, but the sta2x11_dma_ops
also added an additional translation on the return value from
x86_swiotlb_alloc_coherent, which is only correct if that functions
returns a direct allocation and not a swiotlb buffer. With the
generic swiotlb and DMA-direct code phys_to_dma is not always used
and the separate sta2x11_dma_ops can be replaced with a simple
bit that marks if the additional physical to DMA address translation
is needed.
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jon Mason <jdmason@kudzu.us>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Muli Ben-Yehuda <mulix@mulix.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: iommu@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/20180319103826.12853-5-hch@lst.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The generic DMA-direct (CONFIG_DMA_DIRECT_OPS=y) implementation is now
functionally equivalent to the x86 nommu dma_map implementation, so
switch over to using it.
That includes switching from using x86_dma_supported in various IOMMU
drivers to use dma_direct_supported instead, which provides the same
functionality.
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jon Mason <jdmason@kudzu.us>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Muli Ben-Yehuda <mulix@mulix.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: iommu@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/20180319103826.12853-4-hch@lst.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
These days all devices (including the ISA fallback device) have a coherent
DMA mask set, so remove the workaround.
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jon Mason <jdmason@kudzu.us>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Muli Ben-Yehuda <mulix@mulix.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: iommu@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/20180319103826.12853-3-hch@lst.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There were only a few Pentium Pro multiprocessors systems where this
errata applied. They are more than 20 years old now, and we've slowly
dropped places which put the workarounds in and discouraged anyone
from enabling the workaround.
Get rid of it for good.
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jon Mason <jdmason@kudzu.us>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Muli Ben-Yehuda <mulix@mulix.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: iommu@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/20180319103826.12853-2-hch@lst.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86/pti updates from Thomas Gleixner:
"Another set of melted spectrum updates:
- Iron out the last late microcode loading issues by actually
checking whether new microcode is present and preventing the CPU
synchronization to run into a timeout induced hang.
- Remove Skylake C2 from the microcode blacklist according to the
latest Intel documentation
- Fix the VM86 POPF emulation which traps if VIP is set, but VIF is
not. Enhance the selftests to catch that kind of issue
- Annotate indirect calls/jumps for objtool on 32bit. This is not a
functional issue, but for consistency sake its the right thing to
do.
- Fix a jump label build warning observed on SPARC64 which uses 32bit
storage for the code location which is casted to 64 bit pointer w/o
extending it to 64bit first.
- Add two new cpufeature bits. Not really an urgent issue, but
provides them for both x86 and x86/kvm work. No impact on the
current kernel"
* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/microcode: Fix CPU synchronization routine
x86/microcode: Attempt late loading only when new microcode is present
x86/speculation: Remove Skylake C2 from Speculation Control microcode blacklist
jump_label: Fix sparc64 warning
x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32-bit kernels
x86/vm86/32: Fix POPF emulation
selftests/x86/entry_from_vm86: Add test cases for POPF
selftests/x86/entry_from_vm86: Exit with 1 if we fail
x86/cpufeatures: Add Intel PCONFIG cpufeature
x86/cpufeatures: Add Intel Total Memory Encryption cpufeature
Return UCODE_NEW from the scanning functions to denote that new microcode
was found and only then attempt the expensive synchronization dance.
Reported-by: Emanuel Czirai <xftroxgpx@protonmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Emanuel Czirai <xftroxgpx@protonmail.com>
Tested-by: Ashok Raj <ashok.raj@intel.com>
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lkml.kernel.org/r/20180314183615.17629-1-bp@alien8.de
Device drivers use get_device_system_crosststamp() to produce precise
system/device cross-timestamps. The PHC clock and ALSA interfaces, for
example, make the cross-timestamps available to user applications. On
Intel platforms, get_device_system_crosststamp() requires a TSC value
derived from ART (Always Running Timer) to compute the monotonic raw and
realtime system timestamps.
Starting with Intel Goldmont platforms, the PCIe root complex supports the
PTM time sync protocol. PTM requires all timestamps to be in units of
nanoseconds. The Intel root complex hardware propagates system time derived
from ART in units of nanoseconds performing the conversion as follows:
ART_NS = ART * 1e9 / <crystal frequency>
When user software requests a cross-timestamp, the system timestamps
(generally read from device registers) must be converted to TSC by the
driver software as follows:
TSC = ART_NS * TSC_KHZ / 1e6
This is valid when CPU feature flag X86_FEATURE_TSC_KNOWN_FREQ is set
indicating that tsc_khz is derived from CPUID[15H]. Drivers should check
whether this flag is set before conversion to TSC is attempted.
Suggested-by: Christopher S. Hall <christopher.s.hall@intel.com>
Signed-off-by: Rajvi Jingar <rajvi.jingar@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: peterz@infradead.org
Link: https://lkml.kernel.org/r/1520530116-4925-1-git-send-email-rajvi.jingar@intel.com
In the following commit:
9e0e3c5130 ("x86/speculation, objtool: Annotate indirect calls/jumps for objtool")
... we added annotations for CALL_NOSPEC/JMP_NOSPEC on 64-bit x86 kernels,
but we did not annotate the 32-bit path.
Annotate it similarly.
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: 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/20180314112427.22351-1-apw@canonical.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Some ACPI hardware reduced platforms need to initialize certain devices
defined by the ACPI hardware specification even though in principle
those devices should not be present in an ACPI hardware reduced platform.
To allow that to happen, make it possible to override the generic
x86_init callbacks and provide a custom legacy_pic value, add a new
->reduced_hw_early_init() callback to struct x86_init_acpi and make
acpi_reduced_hw_init() use it.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-acpi@vger.kernel.org
Link: http://lkml.kernel.org/r/20180220180506.65523-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This is a preparation patch to allow override the hardware reduced
initialization on ACPI enabled platforms.
No functional change intended.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-acpi@vger.kernel.org
Link: http://lkml.kernel.org/r/20180220180506.65523-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The comments are factored out from the code changes to make them
easier to read. Add them separately to explain some non-obvious
aspects.
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: kasan-dev@googlegroups.com
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/cc595efc644bb905407012d82d3eb8bac3368e7a.1517246437.git.dvyukov@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add arch_ prefix to all atomic operations and include
<asm-generic/atomic-instrumented.h>. This will allow
to add KASAN instrumentation to all atomic ops.
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: kasan-dev@googlegroups.com
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/54f0eb64260b84199e538652e079a89b5423ad41.1517246437.git.dvyukov@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
