Commit Graph

18 Commits

Author SHA1 Message Date
Linus Torvalds
2a4c0c11c0 s390 updates for 7.1 merge window
- Add support for CONFIG_PAGE_TABLE_CHECK and enable it in
   debug_defconfig. s390 can only tell user from kernel PTEs via the mm,
   so mm_struct is now passed into pxx_user_accessible_page() callbacks
 
 - Expose the PCI function UID as an arch-specific slot attribute in
   sysfs so a function can be identified by its user-defined id while
   still in standby. Introduces a generic ARCH_PCI_SLOT_GROUPS hook in
   drivers/pci/slot.c
 
 - Refresh s390 PCI documentation to reflect current behavior and cover
   previously undocumented sysfs attributes
 
 - zcrypt device driver cleanup series: consistent field types, clearer
   variable naming, a kernel-doc warning fix, and a comment explaining
   the intentional synchronize_rcu() in pkey_handler_register()
 
 - Provide an s390 arch_raw_cpu_ptr() that avoids the detour via
   get_lowcore() using alternatives, shrinking defconfig by ~27 kB
 
 - Guard identity-base randomization with kaslr_enabled() so nokaslr
   keeps the identity mapping at 0 even with
   CONFIG_RANDOMIZE_IDENTITY_BASE=y
 
 - Build S390_MODULES_SANITY_TEST as a module only by requiring
   KUNIT && m, since built-in would not exercise module loading
 
 - Remove the permanently commented-out HMCDRV_DEV_CLASS create_class()
   code in the hmcdrv driver
 
 - Drop stale ident_map_size extern conflicting with asm/page.h
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Merge tag 's390-7.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

Pull s390 updates from Vasily Gorbik:

 - Add support for CONFIG_PAGE_TABLE_CHECK and enable it in
   debug_defconfig. s390 can only tell user from kernel PTEs via the mm,
   so mm_struct is now passed into pxx_user_accessible_page() callbacks

 - Expose the PCI function UID as an arch-specific slot attribute in
   sysfs so a function can be identified by its user-defined id while
   still in standby. Introduces a generic ARCH_PCI_SLOT_GROUPS hook in
   drivers/pci/slot.c

 - Refresh s390 PCI documentation to reflect current behavior and cover
   previously undocumented sysfs attributes

 - zcrypt device driver cleanup series: consistent field types, clearer
   variable naming, a kernel-doc warning fix, and a comment explaining
   the intentional synchronize_rcu() in pkey_handler_register()

 - Provide an s390 arch_raw_cpu_ptr() that avoids the detour via
   get_lowcore() using alternatives, shrinking defconfig by ~27 kB

 - Guard identity-base randomization with kaslr_enabled() so nokaslr
   keeps the identity mapping at 0 even with RANDOMIZE_IDENTITY_BASE=y

 - Build S390_MODULES_SANITY_TEST as a module only by requiring KUNIT &&
   m, since built-in would not exercise module loading

 - Remove the permanently commented-out HMCDRV_DEV_CLASS create_class()
   code in the hmcdrv driver

 - Drop stale ident_map_size extern conflicting with asm/page.h

* tag 's390-7.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/zcrypt: Fix warning about wrong kernel doc comment
  PCI: s390: Expose the UID as an arch specific PCI slot attribute
  docs: s390/pci: Improve and update PCI documentation
  s390/pkey: Add comment about synchronize_rcu() to pkey base
  s390/hmcdrv: Remove commented out code
  s390/zcrypt: Slight rework on the agent_id field
  s390/zcrypt: Explicitly use a card variable in _zcrypt_send_cprb
  s390/zcrypt: Rework MKVP fields and handling
  s390/zcrypt: Make apfs a real unsigned int field
  s390/zcrypt: Rework domain processing within zcrypt device driver
  s390/zcrypt: Move inline function rng_type6cprb_msgx from header to code
  s390/percpu: Provide arch_raw_cpu_ptr()
  s390: Enable page table check for debug_defconfig
  s390/pgtable: Add s390 support for page table check
  s390/pgtable: Use set_pmd_bit() to invalidate PMD entry
  mm/page_table_check: Pass mm_struct to pxx_user_accessible_page()
  s390/boot: Respect kaslr_enabled() for identity randomization
  s390/Kconfig: Make modules sanity test a module-only option
  s390/setup: Drop stale ident_map_size declaration
2026-04-22 11:13:45 -07:00
Niklas Schnelle
e4f9ab031d PCI: s390: Expose the UID as an arch specific PCI slot attribute
On s390, an individual PCI function can generally be identified by two
identifiers, the FID and the UID. Which identifier is used depends on
the scope and the platform configuration.

The first identifier, the FID, is always available and identifies a PCI
device uniquely within a machine. The FID may be virtualized by
hypervisors, but on the LPAR level, the machine scope makes it
impossible to create the same configuration based on FIDs on two
different LPARs of the same machine, and difficult to reuse across
machines.

Such matching LPAR configurations are useful, though, allowing
standardized setups and booting a Linux installation on different LPARs.
To this end the UID, or user-defined identifier, was introduced. While
it is only guaranteed to be unique within an LPAR and only if indicated
by firmware, it allows users to replicate PCI device setups.

On s390, which uses a machine hypervisor, a per PCI function hotplug
model is used. The shortcoming with the UID then is, that it is not
visible to the user without first attaching the PCI function and
accessing the "uid" device attribute. The FID, on the other hand, is
used as the slot name and is thus known even with the PCI function in
standby.

Remedy this shortcoming by providing the UID as an attribute on the slot
allowing the user to identify a PCI function based on the UID without
having to first attach it. Do this via a macro mechanism analogous to
what was introduced by commit 265baca69a ("s390/pci: Stop usurping
pdev->dev.groups") for the PCI device attributes.

Reviewed-by: Gerd Bayer <gbayer@linux.ibm.com>
Reviewed-by: Julian Ruess <julianr@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com> # drivers/pci/slot.c
Link: https://lore.kernel.org/r/20260407-uid_slot-v8-2-15ae4409d2ce@linux.ibm.com
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2026-04-11 11:18:15 +02:00
Niklas Schnelle
737c4f4a24 docs: s390/pci: Improve and update PCI documentation
Update the s390 specific PCI documentation to better reflect current
behavior and terms such as the handling of Isolated VFs via commit
25f39d3dcb ("s390/pci: Ignore RID for isolated VFs").

Add a descriptions for /sys/firmware/clp/uid_checking which was added
in commit b043a81ce3 ("s390/pci: Expose firmware provided UID Checking
state in sysfs") but missed documentation.

Similarly add documentation for the fidparm attribute added by commit
99ad39306a ("s390/pci: Expose FIDPARM attribute in sysfs") and
add a list of pft values and their names.

Finally improve formatting of the different attribute descriptions by
adding a separating colon.

Reviewed-by: Farhan Ali <alifm@linux.ibm.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Gerd Bayer <gbayer@linux.ibm.com>
Link: https://lore.kernel.org/r/20260407-uid_slot-v8-1-15ae4409d2ce@linux.ibm.com
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2026-04-11 11:18:15 +02:00
Paolo Bonzini
3c443ec743 vfio: remove dead notifier code
group->notifier is dead code. VFIO initializes it and checks it for
emptiness on teardown, but nobody ever registers on it or triggers it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Anthony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20260407175934.1602711-1-pbonzini@redhat.com
Signed-off-by: Alex Williamson <alex@shazbot.org>
2026-04-10 13:32:25 -06:00
Linus Torvalds
72c395024d A slightly calmer cycle for docs this time around, though there is still a
fair amount going on, including:
 
 - Some signs of life on the long-moribund Japanese translation
 
 - Documentation on policies around the use of generative tools for patch
   submissions, and a separate document intended for consumption by
   generative tools.
 
 - The completion of the move of the documentation tools to tools/docs.  For
   now we're leaving a /scripts/kernel-doc symlink behind to avoid breaking
   scripts.
 
 - Ongoing build-system work includes the incorporation of documentation in
   Python code, better support for documenting variables, and lots of
   improvements and fixes.
 
 - Automatic linking of man-page references -- cat(1), for example -- to
   the online pages in the HTML build.
 
 ...and the usual array of typo fixes and such.
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Merge tag 'docs-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/docs/linux

Pull documentation updates from Jonathan Corbet:
 "A slightly calmer cycle for docs this time around, though there is
  still a fair amount going on, including:

   - Some signs of life on the long-moribund Japanese translation

   - Documentation on policies around the use of generative tools for
     patch submissions, and a separate document intended for consumption
     by generative tools

   - The completion of the move of the documentation tools to
     tools/docs. For now we're leaving a /scripts/kernel-doc symlink
     behind to avoid breaking scripts

   - Ongoing build-system work includes the incorporation of
     documentation in Python code, better support for documenting
     variables, and lots of improvements and fixes

   - Automatic linking of man-page references -- cat(1), for example --
     to the online pages in the HTML build

  ...and the usual array of typo fixes and such"

* tag 'docs-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/docs/linux: (107 commits)
  doc: development-process: add notice on testing
  tools: sphinx-build-wrapper: improve its help message
  docs: sphinx-build-wrapper: allow -v override -q
  docs: kdoc: Fix pdfdocs build for tools
  docs: ja_JP: process: translate 'Obtain a current source tree'
  docs: fix 're-use' -> 'reuse' in documentation
  docs: ioctl-number: fix a typo in ioctl-number.rst
  docs: filesystems: ensure proc pid substitutable is complete
  docs: automarkup.py: Skip common English words as C identifiers
  Documentation: use a source-read extension for the index link boilerplate
  docs: parse_features: make documentation more consistent
  docs: add parse_features module documentation
  docs: jobserver: do some documentation improvements
  docs: add jobserver module documentation
  docs: kabi: helpers: add documentation for each "enum" value
  docs: kabi: helpers: add helper for debug bits 7 and 8
  docs: kabi: system_symbols: end docstring phrases with a dot
  docs: python: abi_regex: do some improvements at documentation
  docs: python: abi_parser: do some improvements at documentation
  docs: add kabi modules documentation
  ...
2026-02-09 20:53:18 -08:00
Rhys Tumelty
78a00cac1e docs: fix 're-use' -> 'reuse' in documentation
Signed-off-by: Rhys Tumelty <rhys@tumelty.co.uk>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20260128220233.179439-1-rhys@tumelty.co.uk>
2026-02-02 09:54:15 -07:00
Gerd Bayer
0d453ba040 s390/Kconfig: Define non-zero ILLEGAL_POINTER_VALUE
Define CONFIG_ILLEGAL_POINTER_VALUE to the eye-catching non-zero value
of 0xdead000000000000, consistent with other architectures. Assert at
compile-time that the poison pointers that include/linux/poison.h
defines based on this illegal pointer are beyond the largest useful
virtual addresses. Also, assert at compile-time that the range of poison
pointers per include/linux/poison.h (currently a range of less than
0x10000 addresses) does not overlap with the range used for address
handles for s390's non-MIO PCI instructions.

This enables s390 to track the DMA mappings by the network stack's
page_pool that was introduced with [0]. Other functional changes are not
intended.

Other archictectures have introduced this for various other reasons with
commit 5c178472af ("riscv: define ILLEGAL_POINTER_VALUE for 64bit")
commit f6853eb561 ("powerpc/64: Define ILLEGAL_POINTER_VALUE for 64-bit")
commit bf0c4e0473 ("arm64: kconfig: Move LIST_POISON to a safe value")
commit a29815a333 ("core, x86: make LIST_POISON less deadly")

[0] https://lore.kernel.org/all/20250409-page-pool-track-dma-v9-0-6a9ef2e0cba8@redhat.com/

Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Gerd Bayer <gbayer@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2026-01-27 12:21:20 +01:00
Jani Nikula
a592a36e49 Documentation: use a source-read extension for the index link boilerplate
The root document usually has a special :ref:`genindex` link to the
generated index. This is also the case for Documentation/index.rst. The
other index.rst files deeper in the directory hierarchy usually don't.

For SPHINXDIRS builds, the root document isn't Documentation/index.rst,
but some other index.rst in the hierarchy. Currently they have a
".. only::" block to add the index link when doing SPHINXDIRS html
builds.

This is obviously very tedious and repetitive. The link is also added to
all index.rst files in the hierarchy for SPHINXDIRS builds, not just the
root document.

Put the boilerplate in a sphinx-includes/subproject-index.rst file, and
include it at the end of the root document for subproject builds in an
ad-hoc source-read extension defined in conf.py.

For now, keep having the boilerplate in translations, because this
approach currently doesn't cover translated index link headers.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Tested-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
[jc: did s/doctree/kern_doc_dir/ ]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20260123143149.2024303-1-jani.nikula@intel.com>
2026-01-23 11:59:34 -07:00
Peter Oberparleiter
2a2153a2ba s390/debug: Update description of resize operation
With commit 1204777867 ("s390/debug: keep debug data on resize")
the behavior of a debug area resize operation was changed. Update the
associated documentation to reflect this change.

Fixes: 1204777867 ("s390/debug: keep debug data on resize")
Reported-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-11-17 11:55:16 +01:00
Nagamani PV
727258025b s390/net: Remove NETIUCV device driver
The netiucv driver creates TCP/IP interfaces over IUCV between Linux
guests on z/VM and other z/VM entities.

Rationale for removal:
- NETIUCV connections are only supported for compatibility with
  earlier versions and not to be used for new network setups,
  since at least Linux kernel 4.0.
- No known active users, use cases, or product dependencies
- The driver is no longer relevant for z/VM networking;
  preferred methods include:
	* Device pass-through (e.g., OSA, RoCE)
	* z/VM Virtual Switch (VSWITCH)

The IUCV mechanism itself remains supported and is actively used
via AF_IUCV, hvc_iucv, and smsg_iucv.

Signed-off-by: Nagamani PV <nagamani@linux.ibm.com>
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250715074210.3999296-1-wintera@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-07-16 17:53:40 -07:00
Aswin Karuvally
6cccb3bb05 s390/net: Remove LCS driver
The original Open Systems Adapter (OSA) was introduced by IBM in the
mid-90s. These were then superseded by OSA-Express in 1999 which used
Queued Direct IO to greatly improve throughput. The newer cards
retained the older, slower non-QDIO (OSE) modes for compatibility with
older systems. In Linux, the lcs driver was responsible for cards
operating in the older OSE mode and the qeth driver was introduced to
allow the OSA-Express cards to operate in the newer QDIO (OSD) mode.

For an S390 machine from 1998 or later, there is no reason to use the
OSE mode and lcs driver as all OSA cards since 1999 provide the faster
OSD mode. As a result, it's been years since we have heard of a
customer configuration involving the lcs driver.

This patch removes the lcs driver. The technology it supports has been
obsolete for past 25+ years and is irrelevant for current use cases.

Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Aswin Karuvally <aswin@linux.ibm.com>
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250204103135.1619097-1-wintera@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-02-05 18:19:01 -08:00
Jason J. Herne
2d8721364c s390/vfio-ap: Driver feature advertisement
Advertise features of the driver for the benefit of automated tooling
like Libvirt and mdevctl.

Signed-off-by: Jason J. Herne <jjherne@linux.ibm.com>
Reviewed-by: Anthony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Boris Fiuczynski <fiuczy@linux.ibm.com>
Link: https://lore.kernel.org/r/20240916120123.11484-1-jjherne@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-09-23 17:57:04 +02:00
Jason J. Herne
3113a29e25 docs: Update s390 vfio-ap doc for ap_config sysfs attribute
A new sysfs attribute, ap_config, for the vfio_ap driver is
documented.

Signed-off-by: "Jason J. Herne" <jjherne@linux.ibm.com>
Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
Link: https://lore.kernel.org/r/20240415152555.13152-6-jjherne@linux.ibm.com
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
2024-04-22 12:49:18 +02:00
Alexander Gordeev
c98d2ecae0 s390/mm: Uncouple physical vs virtual address spaces
The uncoupling physical vs virtual address spaces brings
the following benefits to s390:

- virtual memory layout flexibility;
- closes the address gap between kernel and modules, it
  caused s390-only problems in the past (e.g. 'perf' bugs);
- allows getting rid of trampolines used for module calls
  into kernel;
- allows simplifying BPF trampoline;
- minor performance improvement in branch prediction;
- kernel randomization entropy is magnitude bigger, as it is
  derived from the amount of available virtual, not physical
  memory;

The whole change could be described in two pictures below:
before and after the change.

Some aspects of the virtual memory layout setup are not
clarified (number of page levels, alignment, DMA memory),
since these are not a part of this change or secondary
with regard to how the uncoupling itself is implemented.

The focus of the pictures is to explain why __va() and __pa()
macros are implemented the way they are.

        Memory layout in V==R mode:

|    Physical      |    Virtual       |
+- 0 --------------+- 0 --------------+ identity mapping start
|                  | S390_lowcore     | Low-address memory
|                  +- 8 KB -----------+
|                  |                  |
|                  | identity         | phys == virt
|                  | mapping          | virt == phys
|                  |                  |
+- AMODE31_START --+- AMODE31_START --+ .amode31 rand. phys/virt start
|.amode31 text/data|.amode31 text/data|
+- AMODE31_END ----+- AMODE31_END ----+ .amode31 rand. phys/virt start
|                  |                  |
|                  |                  |
+- __kaslr_offset, __kaslr_offset_phys| kernel rand. phys/virt start
|                  |                  |
| kernel text/data | kernel text/data | phys == kvirt
|                  |                  |
+------------------+------------------+ kernel phys/virt end
|                  |                  |
|                  |                  |
|                  |                  |
|                  |                  |
+- ident_map_size -+- ident_map_size -+ identity mapping end
                   |                  |
                   |  ... unused gap  |
                   |                  |
                   +---- vmemmap -----+ 'struct page' array start
                   |                  |
                   | virtually mapped |
                   | memory map       |
                   |                  |
                   +- __abs_lowcore --+
                   |                  |
                   | Absolute Lowcore |
                   |                  |
                   +- __memcpy_real_area
                   |                  |
                   |  Real Memory Copy|
                   |                  |
                   +- VMALLOC_START --+ vmalloc area start
                   |                  |
                   |  vmalloc area    |
                   |                  |
                   +- MODULES_VADDR --+ modules area start
                   |                  |
                   |  modules area    |
                   |                  |
                   +------------------+ UltraVisor Secure Storage limit
                   |                  |
                   |  ... unused gap  |
                   |                  |
                   +KASAN_SHADOW_START+ KASAN shadow memory start
                   |                  |
                   |   KASAN shadow   |
                   |                  |
                   +------------------+ ASCE limit

        Memory layout in V!=R mode:

|    Physical      |    Virtual       |
+- 0 --------------+- 0 --------------+
|                  | S390_lowcore     | Low-address memory
|                  +- 8 KB -----------+
|                  |                  |
|                  |                  |
|                  | ... unused gap   |
|                  |                  |
+- AMODE31_START --+- AMODE31_START --+ .amode31 rand. phys/virt start
|.amode31 text/data|.amode31 text/data|
+- AMODE31_END ----+- AMODE31_END ----+ .amode31 rand. phys/virt end (<2GB)
|                  |                  |
|                  |                  |
+- __kaslr_offset_phys		     | kernel rand. phys start
|                  |                  |
| kernel text/data |                  |
|                  |                  |
+------------------+		     | kernel phys end
|                  |                  |
|                  |                  |
|                  |                  |
|                  |                  |
+- ident_map_size -+		     |
                   |                  |
                   |  ... unused gap  |
                   |                  |
                   +- __identity_base + identity mapping start (>= 2GB)
                   |                  |
                   | identity         | phys == virt - __identity_base
                   | mapping          | virt == phys + __identity_base
                   |                  |
                   |                  |
                   |                  |
                   |                  |
                   |                  |
                   |                  |
                   |                  |
                   |                  |
                   |                  |
                   |                  |
                   |                  |
                   |                  |
                   |                  |
                   |                  |
                   |                  |
                   |                  |
                   |                  |
                   +---- vmemmap -----+ 'struct page' array start
                   |                  |
                   | virtually mapped |
                   | memory map       |
                   |                  |
                   +- __abs_lowcore --+
                   |                  |
                   | Absolute Lowcore |
                   |                  |
                   +- __memcpy_real_area
                   |                  |
                   |  Real Memory Copy|
                   |                  |
                   +- VMALLOC_START --+ vmalloc area start
                   |                  |
                   |  vmalloc area    |
                   |                  |
                   +- MODULES_VADDR --+ modules area start
                   |                  |
                   |  modules area    |
                   |                  |
                   +- __kaslr_offset -+ kernel rand. virt start
                   |                  |
                   | kernel text/data | phys == (kvirt - __kaslr_offset) +
                   |                  |         __kaslr_offset_phys
                   +- kernel .bss end + kernel rand. virt end
                   |                  |
                   |  ... unused gap  |
                   |                  |
                   +------------------+ UltraVisor Secure Storage limit
                   |                  |
                   |  ... unused gap  |
                   |                  |
                   +KASAN_SHADOW_START+ KASAN shadow memory start
                   |                  |
                   |   KASAN shadow   |
                   |                  |
                   +------------------+ ASCE limit

Unused gaps in the virtual memory layout could be present
or not - depending on how partucular system is configured.
No page tables are created for the unused gaps.

The relative order of vmalloc, modules and kernel image in
virtual memory is defined by following considerations:

- start of the modules area and end of the kernel should reside
  within 4GB to accommodate relative 32-bit jumps. The best way
  to achieve that is to place kernel next to modules;

- vmalloc and module areas should locate next to each other
  to prevent failures and extra reworks in user level tools
  (makedumpfile, crash, etc.) which treat vmalloc and module
  addresses similarily;

- kernel needs to be the last area in the virtual memory
  layout to easily distinguish between kernel and non-kernel
  virtual addresses. That is needed to (again) simplify
  handling of addresses in user level tools and make __pa()
  macro faster (see below);

Concluding the above, the relative order of the considered
virtual areas in memory is: vmalloc - modules - kernel.
Therefore, the only change to the current memory layout is
moving kernel to the end of virtual address space.

With that approach the implementation of __pa() macro is
straightforward - all linear virtual addresses less than
kernel base are considered identity mapping:

	phys == virt - __identity_base

All addresses greater than kernel base are kernel ones:

	phys == (kvirt - __kaslr_offset) + __kaslr_offset_phys

By contrast, __va() macro deals only with identity mapping
addresses:

	virt == phys + __identity_base

.amode31 section is mapped separately and is not covered by
__pa() macro. In fact, it could have been handled easily by
checking whether a virtual address is within the section or
not, but there is no need for that. Thus, let __pa() code
do as little machine cycles as possible.

The KASAN shadow memory is located at the very end of the
virtual memory layout, at addresses higher than the kernel.
However, that is not a linear mapping and no code other than
KASAN instrumentation or API is expected to access it.

When KASLR mode is enabled the kernel base address randomized
within a memory window that spans whole unused virtual address
space. The size of that window depends from the amount of
physical memory available to the system, the limit imposed by
UltraVisor (if present) and the vmalloc area size as provided
by vmalloc= kernel command line parameter.

In case the virtual memory is exhausted the minimum size of
the randomization window is forcefully set to 2GB, which
amounts to in 15 bits of entropy if KASAN is enabled or 17
bits of entropy in default configuration.

The default kernel offset 0x100000 is used as a magic value
both in the decompressor code and vmlinux linker script, but
it will be removed with a follow-up change.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
2024-04-17 13:38:01 +02:00
Holger Dengler
123760841a s390/ap: modularize ap bus
There is no hard requirement to have the ap bus statically in the
kernel, so add an option to compile it as module.

Cc: Tony Krowiak <akrowiak@linux.ibm.com>
Cc: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Holger Dengler <dengler@linux.ibm.com>
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Anthony Krowiak <akrowiak@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
2024-04-09 17:29:56 +02:00
Vegard Nossum
c48a7c44a1 docs: kernel_feat.py: fix potential command injection
The kernel-feat directive passes its argument straight to the shell.
This is unfortunate and unnecessary.

Let's always use paths relative to $srctree/Documentation/ and use
subprocess.check_call() instead of subprocess.Popen(shell=True).

This also makes the code shorter.

This is analogous to commit 3231dd5862 ("docs: kernel_abi.py: fix
command injection") where we did exactly the same thing for
kernel_abi.py, somehow I completely missed this one.

Link: https://fosstodon.org/@jani/111676532203641247
Reported-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240110174758.3680506-1-vegard.nossum@oracle.com
2024-01-11 09:21:01 -07:00
Linus Torvalds
cd99b9eb4b Documentation work keeps chugging along; stuff for 6.6 includes:
- Work from Carlos Bilbao to integrate rustdoc output into the generated
   HTML documentation.  This took some work to figure out how to do it
   without slowing the docs build and without creating people who don't have
   Rust installed, but Carlos got there.
 
 - Move the loongarch and mips architecture documentation under
   Documentation/arch/.
 
 - Some more maintainer documentation from Jakub
 
 ...plus the usual assortment of updates, translations, and fixes.
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Merge tag 'docs-6.6' of git://git.lwn.net/linux

Pull documentation updates from Jonathan Corbet:
 "Documentation work keeps chugging along; this includes:

   - Work from Carlos Bilbao to integrate rustdoc output into the
     generated HTML documentation. This took some work to figure out how
     to do it without slowing the docs build and without creating people
     who don't have Rust installed, but Carlos got there

   - Move the loongarch and mips architecture documentation under
     Documentation/arch/

   - Some more maintainer documentation from Jakub

  ... plus the usual assortment of updates, translations, and fixes"

* tag 'docs-6.6' of git://git.lwn.net/linux: (56 commits)
  Docu: genericirq.rst: fix irq-example
  input: docs: pxrc: remove reference to phoenix-sim
  Documentation: serial-console: Fix literal block marker
  docs/mm: remove references to hmm_mirror ops and clean typos
  docs/zh_CN: correct regi_chg(),regi_add() to region_chg(),region_add()
  Documentation: Fix typos
  Documentation/ABI: Fix typos
  scripts: kernel-doc: fix macro handling in enums
  scripts: kernel-doc: parse DEFINE_DMA_UNMAP_[ADDR|LEN]
  Documentation: riscv: Update boot image header since EFI stub is supported
  Documentation: riscv: Add early boot document
  Documentation: arm: Add bootargs to the table of added DT parameters
  docs: kernel-parameters: Refer to the correct bitmap function
  doc: update params of memhp_default_state=
  docs: Add book to process/kernel-docs.rst
  docs: sparse: fix invalid link addresses
  docs: vfs: clean up after the iterate() removal
  docs: Add a section on surveys to the researcher guidelines
  docs: move mips under arch
  docs: move loongarch under arch
  ...
2023-08-30 20:05:42 -07:00
Costa Shulyupin
37002bc6b6 docs: move s390 under arch
and fix all in-tree references.

Architecture-specific documentation is being moved into Documentation/arch/
as a way of cleaning up the top-level documentation directory and making
the docs hierarchy more closely match the source hierarchy.

Signed-off-by: Costa Shulyupin <costa.shul@redhat.com>
Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20230718045550.495428-1-costa.shul@redhat.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2023-07-24 12:12:24 +02:00