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struct setup_data.len is the length of data field. In case of
SETUP_INDIRECT, it should be sizeof(setup_indirect).
Signed-off-by: Cao jin <jojing64@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Link: https://lore.kernel.org/r/20210127084911.63438-1-jojing64@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Pull documentation updates from Jonathan Corbet:
"A much quieter cycle for documentation (happily), with, one hopes, the
bulk of the churn behind us. Significant stuff in this pull includes:
- A set of new Chinese translations
- Italian translation updates
- A mechanism from Mauro to automatically format
Documentation/features for the built docs
- Automatic cross references without explicit :ref: markup
- A new reset-controller document
- An extensive new document on reporting problems from Thorsten
That last patch also adds the CC-BY-4.0 license to LICENSES/dual;
there was some discussion on this, but we seem to have consensus and
an ack from Greg for that addition"
* tag 'docs-5.11' of git://git.lwn.net/linux: (50 commits)
docs: fix broken cross reference in translations/zh_CN
docs: Note that sphinx 1.7 will be required soon
docs: update requirements to install six module
docs: reporting-issues: move 'outdated, need help' note to proper place
docs: Update documentation to reflect what TAINT_CPU_OUT_OF_SPEC means
docs: add a reset controller chapter to the driver API docs
docs: make reporting-bugs.rst obsolete
docs: Add a new text describing how to report bugs
LICENSES: Add the CC-BY-4.0 license
Documentation: fix multiple typos found in the admin-guide subdirectory
Documentation: fix typos found in admin-guide subdirectory
kernel-doc: Fix example in Nested structs/unions
docs: clean up sysctl/kernel: titles, version
docs: trace: fix event state structure name
docs: nios2: add missing ReST file
scripts: get_feat.pl: reduce table width for all features output
scripts: get_feat.pl: change the group by order
scripts: get_feat.pl: make complete table more coincise
scripts: kernel-doc: fix parsing function-like typedefs
Documentation: fix typos found in process, dev-tools, and doc-guide subdirectories
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cache resource control updates from Borislav Petkov:
- add logic to correct MBM total and local values fixing errata SKX99
and BDF102 (Fenghua Yu)
- cleanups
* tag 'x86_cache_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/resctrl: Clean up unused function parameter in rmdir path
x86/resctrl: Constify kernfs_ops
x86/resctrl: Correct MBM total and local values
Documentation/x86: Rename resctrl_ui.rst and add two errata to the file
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cpuid updates from Borislav Petkov:
"Only AMD-specific changes this time:
- Save the AMD physical die ID into cpuinfo_x86.cpu_die_id and
convert all code to use it (Yazen Ghannam)
- Remove a dead and unused TSEG region remapping workaround on AMD
(Arvind Sankar)"
* tag 'x86_cpu_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/cpu/amd: Remove dead code for TSEG region remapping
x86/topology: Set cpu_die_id only if DIE_TYPE found
EDAC/mce_amd: Use struct cpuinfo_x86.cpu_die_id for AMD NodeId
x86/CPU/AMD: Remove amd_get_nb_id()
x86/CPU/AMD: Save AMD NodeId as cpu_die_id
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Add a feature list matrix for each architecture to their
respective Kernel books.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/9c39d4dd93e05c0008205527d2c3450912f029ed.1606748711.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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AMD systems provide a "NodeId" value that represents a global ID
indicating to which "Node" a logical CPU belongs. The "Node" is a
physical structure equivalent to a Die, and it should not be confused
with logical structures like NUMA nodes. Logical nodes can be adjusted
based on firmware or other settings whereas the physical nodes/dies are
fixed based on hardware topology.
The NodeId value can be used when a physical ID is needed by software.
Save the AMD NodeId to struct cpuinfo_x86.cpu_die_id. Use the value
from CPUID or MSR as appropriate. Default to phys_proc_id otherwise.
Do so for both AMD and Hygon systems.
Drop the node_id parameter from cacheinfo_*_init_llc_id() as it is no
longer needed.
Update the x86 topology documentation.
Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20201109210659.754018-2-Yazen.Ghannam@amd.com
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Document the Intel SGX kernel architecture. The fine-grained architecture
details can be looked up from Intel SDM Volume 3D.
Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Jethro Beekman <jethro@fortanix.com>
Cc: linux-doc@vger.kernel.org
Link: https://lkml.kernel.org/r/20201112220135.165028-24-jarkko@kernel.org
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Intel Memory Bandwidth Monitoring (MBM) counters may report system
memory bandwidth incorrectly on some Intel processors. This is reported
in documented in erratum SKX99, erratum BDF102 and in the RDT reference
manual, see Documentation/x86/index.rst.
To work around the errata, MBM total and local readings are corrected
using a correction factor table.
Since the correction factor table is not publicly documented anywhere,
document the table and the errata in Documentation/x86/resctrl.rst for
future reference.
[ bp: Move web links to the doc, massage. ]
Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20201014004927.1839452-2-fenghua.yu@intel.com
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Pull documentation fixes from Jonathan Corbet:
"A handful of late-arriving documentation fixes"
* tag 'docs-5.10-2' of git://git.lwn.net/linux:
docs: Add two missing entries in vm sysctl index
docs/vm: trivial fixes to several spelling mistakes
docs: submitting-patches: describe preserving review/test tags
Documentation: Chinese translation of Documentation/arm64/hugetlbpage.rst
Documentation: x86: fix a missing word in x86_64/mm.rst.
docs: driver-api: remove a duplicated index entry
docs: lkdtm: Modernize and improve details
docs: deprecated.rst: Expand str*cpy() replacement notes
docs/cpu-load: format the example code.
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This patch adds a missing word in x86/x86_64/mm.rst, without which
the note reads awkwardly.
Signed-off-by: Wei Lin Chang <r09922117@csie.ntu.edu.tw>
Link: https://lore.kernel.org/r/20201015062242.26296-1-r09922117@csie.ntu.edu.tw
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux
Pull devicetree updates from Rob Herring:
- Update dtc to upstream version v1.6.0-31-gcbca977ea121
- dtx_diff help text reformatting
- Speed-up validation time for binding and dtb checks using json for
intermediate files
- Add support for running yamllint on DT schema files
- Remove old booting-without-of.rst
- Extend the example schema to address common issues
- Cleanup handling of additionalProperties/unevaluatedProperties
- Ensure all DSI controller schemas reference dsi-controller.yaml
- Vendor prefixes for Zealz, Wandbord/Technexion, Embest RIoT, Rex,
DFI, and Cisco Meraki
- Convert at25, SPMI bus, TI hwlock, HiSilicon Hi3660 USB3 PHY, Arm
SP805 watchdog, Arm SP804, and Samsung 11-pin USB connector to DT
schema
- Convert HiSilicon SoC and syscon bindings to DT schema
- Convert SiFive Risc-V L2 cache, PLIC, PRCI, and PWM to DT schema
- Convert i.MX bindings for w1, crypto, rng, SIM, PM, DDR, SATA, vf610
GPIO, and UART to DT schema
- Add i.MX 8M compatible strings
- Add LM81 and DS1780 as trivial devices
- Various missing properties added to fix dtb validation warnings
* tag 'devicetree-for-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux: (111 commits)
dt-bindings: misc: explicitly add #address-cells for slave mode
spi: dt-bindings: spi-controller: explicitly require #address-cells=<0> for slave mode
dt: Remove booting-without-of.rst
dt-bindings: update usb-c-connector example
dt-bindings: arm: hisilicon: add missing properties into cpuctrl.yaml
dt-bindings: arm: hisilicon: add missing properties into sysctrl.yaml
dt-bindings: pwm: imx: document i.MX compatibles
scripts/dtc: Update to upstream version v1.6.0-31-gcbca977ea121
dt-bindings: Add running yamllint to dt_binding_check
dt-bindings: powerpc: Add a schema for the 'sleep' property
dt-bindings: pinctrl: sirf: Fix typo abitrary
dt-bindings: pinctrl: qcom: Fix typo abitrary
dt-bindings: Explicitly allow additional properties in common schemas
dt-bindings: Use 'additionalProperties' instead of 'unevaluatedProperties'
dt-bindings: Add missing 'unevaluatedProperties'
Docs: Fixing spelling errors in Documentation/devicetree/bindings/
dt-bindings: arm: hisilicon: convert Hi6220 domain controller bindings to json-schema
dt-bindings: riscv: convert pwm bindings to json-schema
dt-bindings: riscv: convert plic bindings to json-schema
dt-bindings: fu540: prci: convert PRCI bindings to json-schema
...
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Disable parsing of the HMAT for debug, to workaround broken platform
instances, or cases where it is otherwise not wanted.
[rdunlap@infradead.org: fix build when CONFIG_ACPI is not set]
Link: https://lkml.kernel.org/r/70e5ee34-9809-a997-7b49-499e4be61307@infradead.org
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Brice Goglin <Brice.Goglin@inria.fr>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Jia He <justin.he@arm.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Will Deacon <will@kernel.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Hulk Robot <hulkci@huawei.com>
Cc: Jason Yan <yanaijie@huawei.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Link: https://lkml.kernel.org/r/159643095540.4062302.732962081968036212.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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booting-without-of.rst is an ancient document that first outlined
Flattened DeviceTree on PowerPC initially. The DT world has evolved a
lot in the 15 years since and booting-without-of.rst is pretty stale.
The name of the document itself is confusing if you don't understand the
evolution from real 'OpenFirmware'. Most of what booting-without-of.rst
contains is now in the DT specification (which evolved out of the
ePAPR). The few things that weren't documented in the DT specification
are now.
All that remains is the boot entry details, so let's move these to arch
specific documents. The exception is arm which already has the same
details documented.
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-mips@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Borislav Petkov <bp@suse.de>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Signed-off-by: Rob Herring <robh@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cache resource control updates from Borislav Petkov:
- Misc cleanups to the resctrl code in preparation for the ARM side
(James Morse)
- Add support for controlling per-thread memory bandwidth throttling
delay values on hw which supports it (Fenghua Yu)
* tag 'x86_cache_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/resctrl: Enable user to view thread or core throttling mode
x86/resctrl: Enumerate per-thread MBA controls
cacheinfo: Move resctrl's get_cache_id() to the cacheinfo header file
x86/resctrl: Add struct rdt_cache::arch_has_{sparse, empty}_bitmaps
x86/resctrl: Merge AMD/Intel parse_bw() calls
x86/resctrl: Add struct rdt_membw::arch_needs_linear to explain AMD/Intel MBA difference
x86/resctrl: Use is_closid_match() in more places
x86/resctrl: Include pid.h
x86/resctrl: Use container_of() in delayed_work handlers
x86/resctrl: Fix stale comment
x86/resctrl: Remove struct rdt_membw::max_delay
x86/resctrl: Remove unused struct mbm_state::chunks_bw
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull misc x86 fixes fromm Borislav Petkov:
- Ratelimit the message about writes to unrecognized MSRs so that they
don't spam the console log (Chris Down)
- Document how the /proc/cpuinfo machinery works for future reference
(Kyung Min Park, Ricardo Neri and Dave Hansen)
- Correct the current NMI's duration calculation (Libing Zhou)
* tag 'x86_misc_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/nmi: Fix nmi_handle() duration miscalculation
Documentation/x86: Add documentation for /proc/cpuinfo feature flags
x86/msr: Make source of unrecognised MSR writes unambiguous
x86/msr: Prevent userspace MSR access from dominating the console
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 PASID updates from Borislav Petkov:
"Initial support for sharing virtual addresses between the CPU and
devices which doesn't need pinning of pages for DMA anymore.
Add support for the command submission to devices using new x86
instructions like ENQCMD{,S} and MOVDIR64B. In addition, add support
for process address space identifiers (PASIDs) which are referenced by
those command submission instructions along with the handling of the
PASID state on context switch as another extended state.
Work by Fenghua Yu, Ashok Raj, Yu-cheng Yu and Dave Jiang"
* tag 'x86_pasid_for_5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/asm: Add an enqcmds() wrapper for the ENQCMDS instruction
x86/asm: Carve out a generic movdir64b() helper for general usage
x86/mmu: Allocate/free a PASID
x86/cpufeatures: Mark ENQCMD as disabled when configured out
mm: Add a pasid member to struct mm_struct
x86/msr-index: Define an IA32_PASID MSR
x86/fpu/xstate: Add supervisor PASID state for ENQCMD
x86/cpufeatures: Enumerate ENQCMD and ENQCMDS instructions
Documentation/x86: Add documentation for SVA (Shared Virtual Addressing)
iommu/vt-d: Change flags type to unsigned int in binding mm
drm, iommu: Change type of pasid to u32
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The file zero-page.txt does not exit. Add links to zero-page.rst
instead.
[ bp: Massage a bit. ]
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20201002190623.7489-1-xypron.glpk@gmx.de
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ENQCMD and Data Streaming Accelerator (DSA) and all of their associated
features are a complicated stack with lots of interconnected pieces.
This documentation provides a big picture overview for all of the
features.
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Co-developed-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/1600187413-163670-4-git-send-email-fenghua.yu@intel.com
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/proc/cpuinfo shows features which the kernel supports. Some of these
flags are derived from CPUID, and others are derived from other sources,
including some that are entirely software-based. Currently, there is
not any documentation in the kernel about how /proc/cpuinfo flags are
generated and what it means when they are missing.
Add documentation for /proc/cpuinfo feature flags enumeration.
Document how and when x86 feature flags are used. Also discuss what
their presence or absence mean for the kernel and users.
Suggested-by: Dave Hansen <dave.hansen@intel.com>
Co-developed-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Kyung Min Park <kyung.min.park@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20200831183500.15481-1-kyung.min.park@intel.com
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Early Intel hardware implementations of Memory Bandwidth Allocation (MBA)
could only control bandwidth at the processor core level. This meant that
when two processes with different bandwidth allocations ran simultaneously
on the same core the hardware had to resolve this difference. It did so by
applying the higher throttling value (lower bandwidth) to both processes.
Newer implementations can apply different throttling values to each
thread on a core.
Introduce a new resctrl file, "thread_throttle_mode", on Intel systems
that shows to the user how throttling values are allocated, per-core or
per-thread.
On systems that support per-core throttling, the file will display "max".
On newer systems that support per-thread throttling, the file will display
"per-thread".
AMD confirmed in [1] that AMD bandwidth allocation is already at thread
level but that the AMD implementation does not use a memory delay
throttle mode. So to avoid confusion the thread throttling mode would be
UNDEFINED on AMD systems and the "thread_throttle_mode" file will not be
visible.
Originally-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/1598296281-127595-3-git-send-email-fenghua.yu@intel.com
Link: [1] https://lore.kernel.org/lkml/18d277fd-6523-319c-d560-66b63ff606b8@amd.com
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Pull documentation updates from Jonathan Corbet:
"It's been a busy cycle for documentation - hopefully the busiest for a
while to come. Changes include:
- Some new Chinese translations
- Progress on the battle against double words words and non-HTTPS
URLs
- Some block-mq documentation
- More RST conversions from Mauro. At this point, that task is
essentially complete, so we shouldn't see this kind of churn again
for a while. Unless we decide to switch to asciidoc or
something...:)
- Lots of typo fixes, warning fixes, and more"
* tag 'docs-5.9' of git://git.lwn.net/linux: (195 commits)
scripts/kernel-doc: optionally treat warnings as errors
docs: ia64: correct typo
mailmap: add entry for <alobakin@marvell.com>
doc/zh_CN: add cpu-load Chinese version
Documentation/admin-guide: tainted-kernels: fix spelling mistake
MAINTAINERS: adjust kprobes.rst entry to new location
devices.txt: document rfkill allocation
PCI: correct flag name
docs: filesystems: vfs: correct flag name
docs: filesystems: vfs: correct sync_mode flag names
docs: path-lookup: markup fixes for emphasis
docs: path-lookup: more markup fixes
docs: path-lookup: fix HTML entity mojibake
CREDITS: Replace HTTP links with HTTPS ones
docs: process: Add an example for creating a fixes tag
doc/zh_CN: add Chinese translation prefer section
doc/zh_CN: add clearing-warn-once Chinese version
doc/zh_CN: add admin-guide index
doc:it_IT: process: coding-style.rst: Correct __maybe_unused compiler label
futex: MAINTAINERS: Re-add selftests directory
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fsgsbase from Thomas Gleixner:
"Support for FSGSBASE. Almost 5 years after the first RFC to support
it, this has been brought into a shape which is maintainable and
actually works.
This final version was done by Sasha Levin who took it up after Intel
dropped the ball. Sasha discovered that the SGX (sic!) offerings out
there ship rogue kernel modules enabling FSGSBASE behind the kernels
back which opens an instantanious unpriviledged root hole.
The FSGSBASE instructions provide a considerable speedup of the
context switch path and enable user space to write GSBASE without
kernel interaction. This enablement requires careful handling of the
exception entries which go through the paranoid entry path as they
can no longer rely on the assumption that user GSBASE is positive (as
enforced via prctl() on non FSGSBASE enabled systemn).
All other entries (syscalls, interrupts and exceptions) can still just
utilize SWAPGS unconditionally when the entry comes from user space.
Converting these entries to use FSGSBASE has no benefit as SWAPGS is
only marginally slower than WRGSBASE and locating and retrieving the
kernel GSBASE value is not a free operation either. The real benefit
of RD/WRGSBASE is the avoidance of the MSR reads and writes.
The changes come with appropriate selftests and have held up in field
testing against the (sanitized) Graphene-SGX driver"
* tag 'x86-fsgsbase-2020-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
x86/fsgsbase: Fix Xen PV support
x86/ptrace: Fix 32-bit PTRACE_SETREGS vs fsbase and gsbase
selftests/x86/fsgsbase: Add a missing memory constraint
selftests/x86/fsgsbase: Fix a comment in the ptrace_write_gsbase test
selftests/x86: Add a syscall_arg_fault_64 test for negative GSBASE
selftests/x86/fsgsbase: Test ptracer-induced GS base write with FSGSBASE
selftests/x86/fsgsbase: Test GS selector on ptracer-induced GS base write
Documentation/x86/64: Add documentation for GS/FS addressing mode
x86/elf: Enumerate kernel FSGSBASE capability in AT_HWCAP2
x86/cpu: Enable FSGSBASE on 64bit by default and add a chicken bit
x86/entry/64: Handle FSGSBASE enabled paranoid entry/exit
x86/entry/64: Introduce the FIND_PERCPU_BASE macro
x86/entry/64: Switch CR3 before SWAPGS in paranoid entry
x86/speculation/swapgs: Check FSGSBASE in enabling SWAPGS mitigation
x86/process/64: Use FSGSBASE instructions on thread copy and ptrace
x86/process/64: Use FSBSBASE in switch_to() if available
x86/process/64: Make save_fsgs_for_kvm() ready for FSGSBASE
x86/fsgsbase/64: Enable FSGSBASE instructions in helper functions
x86/fsgsbase/64: Add intrinsics for FSGSBASE instructions
x86/cpu: Add 'unsafe_fsgsbase' to enable CR4.FSGSBASE
...
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- Add support for zstd compressed kernel
- Define __DISABLE_EXPORTS in Makefile
- Remove __DISABLE_EXPORTS definition from kaslr.c
- Bump the heap size for zstd.
- Update the documentation.
Integrates the ZSTD decompression code to the x86 pre-boot code.
Zstandard requires slightly more memory during the kernel decompression
on x86 (192 KB vs 64 KB), and the memory usage is independent of the
window size.
__DISABLE_EXPORTS is now defined in the Makefile, which covers both
the existing use in kaslr.c, and the use needed by the zstd decompressor
in misc.c.
This patch has been boot tested with both a zstd and gzip compressed
kernel on i386 and x86_64 using buildroot and QEMU.
Additionally, this has been tested in production on x86_64 devices.
We saw a 2 second boot time reduction by switching kernel compression
from xz to zstd.
Signed-off-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200730190841.2071656-7-nickrterrell@gmail.com
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Drop the doubled word "and".
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: https://lore.kernel.org/r/20200703213107.30758-2-rdunlap@infradead.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
|
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Drop the doubled word "see".
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: https://lore.kernel.org/r/20200703213107.30758-3-rdunlap@infradead.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
|
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Explain how the GS/FS based addressing can be utilized in user space
applications along with the differences between the generic prctl() based
GS/FS base control and the FSGSBASE version available on newer CPUs.
Originally-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20200528201402.1708239-15-sashal@kernel.org
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Pull documentation updates from Jonathan Corbet:
"A fair amount of stuff this time around, dominated by yet another
massive set from Mauro toward the completion of the RST conversion. I
*really* hope we are getting close to the end of this. Meanwhile,
those patches reach pretty far afield to update document references
around the tree; there should be no actual code changes there. There
will be, alas, more of the usual trivial merge conflicts.
Beyond that we have more translations, improvements to the sphinx
scripting, a number of additions to the sysctl documentation, and lots
of fixes"
* tag 'docs-5.8' of git://git.lwn.net/linux: (130 commits)
Documentation: fixes to the maintainer-entry-profile template
zswap: docs/vm: Fix typo accept_threshold_percent in zswap.rst
tracing: Fix events.rst section numbering
docs: acpi: fix old http link and improve document format
docs: filesystems: add info about efivars content
Documentation: LSM: Correct the basic LSM description
mailmap: change email for Ricardo Ribalda
docs: sysctl/kernel: document unaligned controls
Documentation: admin-guide: update bug-hunting.rst
docs: sysctl/kernel: document ngroups_max
nvdimm: fixes to maintainter-entry-profile
Documentation/features: Correct RISC-V kprobes support entry
Documentation/features: Refresh the arch support status files
Revert "docs: sysctl/kernel: document ngroups_max"
docs: move locking-specific documents to locking/
docs: move digsig docs to the security book
docs: move the kref doc into the core-api book
docs: add IRQ documentation at the core-api book
docs: debugging-via-ohci1394.txt: add it to the core-api book
docs: fix references for ipmi.rst file
...
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Signed-off-by: Flavio Suligoi <f.suligoi@asem.it>
Link: https://lore.kernel.org/r/1588080745-21999-1-git-send-email-f.suligoi@asem.it
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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The EFI handover protocol was introduced on x86 to permit the boot
loader to pass a populated boot_params structure as an additional
function argument to the entry point. This allows the bootloader to
pass the base and size of a initrd image, which is more flexible
than relying on the EFI stub's file I/O routines, which can only
access the file system from which the kernel image itself was loaded
from firmware.
This approach requires a fair amount of internal knowledge regarding
the layout of the boot_params structure on the part of the boot loader,
as well as knowledge regarding the allowed placement of the initrd in
memory, and so it has been deprecated in favour of a new initrd loading
method that is based on existing UEFI protocols and best practices.
So update the x86 boot protocol documentation to clarify that the EFI
handover protocol has been deprecated, and while at it, add a note that
invoking the EFI handover protocol still requires the PE/COFF image to
be loaded properly (as opposed to simply being copied into memory).
Also, drop the code32_start header field from the list of values that
need to be provided, as this is no longer required.
Reviewed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200409130434.6736-7-ardb@kernel.org
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cleanups from Ingo Molnar:
"This topic tree contains more commits than usual:
- most of it are uaccess cleanups/reorganization by Al
- there's a bunch of prototype declaration (--Wmissing-prototypes)
cleanups
- misc other cleanups all around the map"
* 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
x86/mm/set_memory: Fix -Wmissing-prototypes warnings
x86/efi: Add a prototype for efi_arch_mem_reserve()
x86/mm: Mark setup_emu2phys_nid() static
x86/jump_label: Move 'inline' keyword placement
x86/platform/uv: Add a missing prototype for uv_bau_message_interrupt()
kill uaccess_try()
x86: unsafe_put-style macro for sigmask
x86: x32_setup_rt_frame(): consolidate uaccess areas
x86: __setup_rt_frame(): consolidate uaccess areas
x86: __setup_frame(): consolidate uaccess areas
x86: setup_sigcontext(): list user_access_{begin,end}() into callers
x86: get rid of put_user_try in __setup_rt_frame() (both 32bit and 64bit)
x86: ia32_setup_rt_frame(): consolidate uaccess areas
x86: ia32_setup_frame(): consolidate uaccess areas
x86: ia32_setup_sigcontext(): lift user_access_{begin,end}() into the callers
x86/alternatives: Mark text_poke_loc_init() static
x86/cpu: Fix a -Wmissing-prototypes warning for init_ia32_feat_ctl()
x86/mm: Drop pud_mknotpresent()
x86: Replace setup_irq() by request_irq()
x86/configs: Slightly reduce defconfigs
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull EFI updates from Ingo Molnar:
"The EFI changes in this cycle are much larger than usual, for two
(positive) reasons:
- The GRUB project is showing signs of life again, resulting in the
introduction of the generic Linux/UEFI boot protocol, instead of
x86 specific hacks which are increasingly difficult to maintain.
There's hope that all future extensions will now go through that
boot protocol.
- Preparatory work for RISC-V EFI support.
The main changes are:
- Boot time GDT handling changes
- Simplify handling of EFI properties table on arm64
- Generic EFI stub cleanups, to improve command line handling, file
I/O, memory allocation, etc.
- Introduce a generic initrd loading method based on calling back
into the firmware, instead of relying on the x86 EFI handover
protocol or device tree.
- Introduce a mixed mode boot method that does not rely on the x86
EFI handover protocol either, and could potentially be adopted by
other architectures (if another one ever surfaces where one
execution mode is a superset of another)
- Clean up the contents of 'struct efi', and move out everything that
doesn't need to be stored there.
- Incorporate support for UEFI spec v2.8A changes that permit
firmware implementations to return EFI_UNSUPPORTED from UEFI
runtime services at OS runtime, and expose a mask of which ones are
supported or unsupported via a configuration table.
- Partial fix for the lack of by-VA cache maintenance in the
decompressor on 32-bit ARM.
- Changes to load device firmware from EFI boot service memory
regions
- Various documentation updates and minor code cleanups and fixes"
* 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (114 commits)
efi/libstub/arm: Fix spurious message that an initrd was loaded
efi/libstub/arm64: Avoid image_base value from efi_loaded_image
partitions/efi: Fix partition name parsing in GUID partition entry
efi/x86: Fix cast of image argument
efi/libstub/x86: Use ULONG_MAX as upper bound for all allocations
efi: Fix a mistype in comments mentioning efivar_entry_iter_begin()
efi/libstub: Avoid linking libstub/lib-ksyms.o into vmlinux
efi/x86: Preserve %ebx correctly in efi_set_virtual_address_map()
efi/x86: Ignore the memory attributes table on i386
efi/x86: Don't relocate the kernel unless necessary
efi/x86: Remove extra headroom for setup block
efi/x86: Add kernel preferred address to PE header
efi/x86: Decompress at start of PE image load address
x86/boot/compressed/32: Save the output address instead of recalculating it
efi/libstub/x86: Deal with exit() boot service returning
x86/boot: Use unsigned comparison for addresses
efi/x86: Avoid using code32_start
efi/x86: Make efi32_pe_entry() more readable
efi/x86: Respect 32-bit ABI in efi32_pe_entry()
efi/x86: Annotate the LOADED_IMAGE_PROTOCOL_GUID with SYM_DATA
...
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Provide more information about __ex_table sorting post link.
The exception tables and fixup tables use a commonly recurring pattern
in the kernel of storing the address of labels as date in custom ELF
sections, then finding these sections, iterating elements within them,
and possibly revisiting them or modifying the data at these addresses.
Sorting readonly arrays to minimize runtime penalties is quite clever.
Suggested-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20200327000951.84071-1-ndesaulniers@google.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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finally
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Changeset 58ad30cf91f0 ("docs: fix reference to core-api/namespaces.rst")
enabled a new feature at Sphinx: it will now generate index for each
document title, plus to each chapter inside it.
There's a drawback, though: one document cannot have two sections
with the same name anymore.
A followup patch will change the logic of autosectionlabel to
avoid most creating references for every single section title,
but still we need to be able to reference the chapters inside
a document.
There are a few places where there are two chapters with the
same name. This patch renames one of the chapters, in order to
avoid symbol conflict within the same document.
PS.: as I don't speach Chinese, I had some help from a friend
(Wen Liu) at the Chinese translation for "publishing patches"
for this document:
Documentation/translations/zh_CN/process/5.Posting.rst
Fixes: 58ad30cf91f0 ("docs: fix reference to core-api/namespaces.rst")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/2bffb91e4a63d41bf5fae1c23e1e8b3bba0b8806.1584716446.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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MPX was removed in commit 45fc24e89b7c ("x86/mpx: remove MPX from
arch/x86"), this removes the corresponding entry in the x86 toc.
This was suggested by a Sphinx warning.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Fixes: 45fc24e89b7cc ("x86/mpx: remove MPX from arch/x86")
Acked-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Commit a24e785111a3 ("i386: paravirt boot sequence") added this flag for
use by paravirtualized environments such as Xen. However, Xen never made
use of this flag [1], and it was only ever used by lguest [2].
Commit ecda85e70277 ("x86/lguest: Remove lguest support") removed
lguest, so KEEP_SEGMENTS has lost its last user.
[1] https://lore.kernel.org/lkml/4D4B097C.5050405@goop.org
[2] https://www.mail-archive.com/lguest@lists.ozlabs.org/msg00469.html
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200202171353.3736319-2-nivedita@alum.mit.edu
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/daveh/x86-mpx
Pull x86 MPX removal from Dave Hansen:
"MPX requires recompiling applications, which requires compiler
support. Unfortunately, GCC 9.1 is expected to be be released without
support for MPX. This means that there was only a relatively small
window where folks could have ever used MPX. It failed to gain wide
adoption in the industry, and Linux was the only mainstream OS to ever
support it widely.
Support for the feature may also disappear on future processors.
This set completes the process that we started during the 5.4 merge
window when the MPX prctl()s were removed. XSAVE support is left in
place, which allows MPX-using KVM guests to continue to function"
* tag 'mpx-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/daveh/x86-mpx:
x86/mpx: remove MPX from arch/x86
mm: remove arch_bprm_mm_init() hook
x86/mpx: remove bounds exception code
x86/mpx: remove build infrastructure
x86/alternatives: add missing insn.h include
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Pull documentation updates from Jonathan Corbet:
"It has been a relatively quiet cycle for documentation, but there's
still a couple of things of note:
- Conversion of the NFS documentation to RST
- A new document on how to help with documentation (and a maintainer
profile entry too)
Plus the usual collection of typo fixes, etc"
* tag 'docs-5.6' of git://git.lwn.net/linux: (40 commits)
docs: filesystems: add overlayfs to index.rst
docs: usb: remove some broken references
scripts/find-unused-docs: Fix massive false positives
docs: nvdimm: use ReST notation for subsection
zram: correct documentation about sysfs node of huge page writeback
Documentation: zram: various fixes in zram.rst
Add a maintainer entry profile for documentation
Add a document on how to contribute to the documentation
docs: Keep up with the location of NoUri
Documentation: Call out example SYM_FUNC_* usage as x86-specific
Documentation: nfs: fault_injection: convert to ReST
Documentation: nfs: pnfs-scsi-server: convert to ReST
Documentation: nfs: convert pnfs-block-server to ReST
Documentation: nfs: idmapper: convert to ReST
Documentation: convert nfsd-admin-interfaces to ReST
Documentation: nfs-rdma: convert to ReST
Documentation: nfsroot.rst: COSMETIC: refill a paragraph
Documentation: nfsroot.txt: convert to ReST
Documentation: convert nfs.txt to ReST
Documentation: filesystems: convert vfat.txt to RST
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cleanups from Ingo Molnar:
"Misc cleanups all around the map"
* 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/CPU/AMD: Remove amd_get_topology_early()
x86/tsc: Remove redundant assignment
x86/crash: Use resource_size()
x86/cpu: Add a missing prototype for arch_smt_update()
x86/nospec: Remove unused RSB_FILL_LOOPS
x86/vdso: Provide missing include file
x86/Kconfig: Correct spelling and punctuation
Documentation/x86/boot: Fix typo
x86/boot: Fix a comment's incorrect file reference
x86/process: Remove set but not used variables prev and next
x86/Kconfig: Fix Kconfig indentation
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From: Dave Hansen <dave.hansen@linux.intel.com>
MPX is being removed from the kernel due to a lack of support
in the toolchain going forward (gcc).
This removes all the remaining (dead at this point) MPX handling
code remaining in the tree. The only remaining code is the XSAVE
support for MPX state which is currently needd for KVM to handle
VMs which might use MPX.
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: x86@kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
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Fix WARNING: Inline emphasis start-string without end-string.
This warning was due to wrong syntax being used.
Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com>
Link: https://lore.kernel.org/r/20191223033121.1584930-1-dwlsalmeida@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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ioremap has provided non-cached semantics by default since the Linux 2.6
days, so remove the additional ioremap_nocache interface.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
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Fix a spelling typo in mm.rst.
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Link: https://lore.kernel.org/r/20191226162138.17601-1-standby24x7@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Fix a Sphinx documentation format warning by breaking a long line
into 2 lines.
Also drop the ':' usage after the Protocol version numbers since
other Protocol versions don't use colons.
Documentation/x86/boot.rst:72: WARNING: Malformed table.
Text in column margin in table line 57.
Fixes: 2c33c27fd603 ("x86/boot: Introduce kernel_info")
Fixes: 00cd1c154d56 ("x86/boot: Introduce kernel_info.setup_type_max")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: https://lore.kernel.org/r/c6fbf592-0aca-69d9-e903-e869221a041a@infradead.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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s/Fileds/Fields/g
Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191203113314.26810-1-info@metux.net
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 boot updates from Ingo Molnar:
"The main changes were:
- Extend the boot protocol to allow future extensions without hitting
the setup_header size limit.
- Add quirk to devicetree systems to disable the RTC unless it's
listed as a supported device.
- Fix ld.lld linker pedantry"
* 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/boot: Introduce setup_indirect
x86/boot: Introduce kernel_info.setup_type_max
x86/boot: Introduce kernel_info
x86/init: Allow DT configured systems to disable RTC at boot time
x86/realmode: Explicitly set entry point via ENTRY in linker script
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The setup_data is a bit awkward to use for extremely large data objects,
both because the setup_data header has to be adjacent to the data object
and because it has a 32-bit length field. However, it is important that
intermediate stages of the boot process have a way to identify which
chunks of memory are occupied by kernel data. Thus introduce an uniform
way to specify such indirect data as setup_indirect struct and
SETUP_INDIRECT type.
And finally bump setup_header version in arch/x86/boot/header.S.
Suggested-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Ross Philipson <ross.philipson@oracle.com>
Reviewed-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: ard.biesheuvel@linaro.org
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: dave.hansen@linux.intel.com
Cc: eric.snowberg@oracle.com
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Juergen Gross <jgross@suse.com>
Cc: kanth.ghatraju@oracle.com
Cc: linux-doc@vger.kernel.org
Cc: linux-efi <linux-efi@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: rdunlap@infradead.org
Cc: ross.philipson@oracle.com
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Cc: xen-devel@lists.xenproject.org
Link: https://lkml.kernel.org/r/20191112134640.16035-4-daniel.kiper@oracle.com
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This field contains maximal allowed type for setup_data.
Do not bump setup_header version in arch/x86/boot/header.S because it
will be followed by additional changes coming into the Linux/x86 boot
protocol.
Suggested-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Ross Philipson <ross.philipson@oracle.com>
Reviewed-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: ard.biesheuvel@linaro.org
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: dave.hansen@linux.intel.com
Cc: eric.snowberg@oracle.com
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Juergen Gross <jgross@suse.com>
Cc: kanth.ghatraju@oracle.com
Cc: linux-doc@vger.kernel.org
Cc: linux-efi <linux-efi@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: rdunlap@infradead.org
Cc: ross.philipson@oracle.com
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Cc: xen-devel@lists.xenproject.org
Link: https://lkml.kernel.org/r/20191112134640.16035-3-daniel.kiper@oracle.com
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The relationships between the headers are analogous to the various data
sections:
setup_header = .data
boot_params/setup_data = .bss
What is missing from the above list? That's right:
kernel_info = .rodata
We have been (ab)using .data for things that could go into .rodata or .bss for
a long time, for lack of alternatives and -- especially early on -- inertia.
Also, the BIOS stub is responsible for creating boot_params, so it isn't
available to a BIOS-based loader (setup_data is, though).
setup_header is permanently limited to 144 bytes due to the reach of the
2-byte jump field, which doubles as a length field for the structure, combined
with the size of the "hole" in struct boot_params that a protected-mode loader
or the BIOS stub has to copy it into. It is currently 119 bytes long, which
leaves us with 25 very precious bytes. This isn't something that can be fixed
without revising the boot protocol entirely, breaking backwards compatibility.
boot_params proper is limited to 4096 bytes, but can be arbitrarily extended
by adding setup_data entries. It cannot be used to communicate properties of
the kernel image, because it is .bss and has no image-provided content.
kernel_info solves this by providing an extensible place for information about
the kernel image. It is readonly, because the kernel cannot rely on a
bootloader copying its contents anywhere, but that is OK; if it becomes
necessary it can still contain data items that an enabled bootloader would be
expected to copy into a setup_data chunk.
Do not bump setup_header version in arch/x86/boot/header.S because it
will be followed by additional changes coming into the Linux/x86 boot
protocol.
Suggested-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Ross Philipson <ross.philipson@oracle.com>
Reviewed-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: ard.biesheuvel@linaro.org
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: dave.hansen@linux.intel.com
Cc: eric.snowberg@oracle.com
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Juergen Gross <jgross@suse.com>
Cc: kanth.ghatraju@oracle.com
Cc: linux-doc@vger.kernel.org
Cc: linux-efi <linux-efi@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: rdunlap@infradead.org
Cc: ross.philipson@oracle.com
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Cc: xen-devel@lists.xenproject.org
Link: https://lkml.kernel.org/r/20191112134640.16035-2-daniel.kiper@oracle.com
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