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Ard Biesheuvel 1db780bafa arm64/mm: Remove randomization of the linear map
Since commit

  97d6786e06 ("arm64: mm: account for hotplug memory when randomizing the linear region")

the decision whether or not to randomize the placement of the system's
DRAM inside the linear map is based on the capabilities of the CPU
rather than how much memory is present at boot time. This change was
necessary because memory hotplug may result in DRAM appearing in places
that are not covered by the linear region at all (and therefore
unusable) if the decision is solely based on the memory map at boot.

In the Android GKI kernel, which requires support for memory hotplug,
and is built with a reduced virtual address space of only 39 bits wide,
randomization of the linear map never happens in practice as a result.
And even on arm64 kernels built with support for 48 bit virtual
addressing, the wider PArange of recent CPUs means that linear map
randomization is slowly becoming a feature that only works on systems
that will soon be obsolete.

So let's just remove this feature. We can always bring it back in an
improved form if there is a real need for it.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250318134949.3194334-2-ardb+git@google.com
Signed-off-by: Will Deacon <will@kernel.org>
2025-04-29 13:21:49 +01:00
Documentation A set of final cleanups for the timer subsystem: 2025-04-06 08:35:37 -07:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
arch arm64/mm: Remove randomization of the linear map 2025-04-29 13:21:49 +01:00
block treewide: Switch/rename to timer_delete[_sync]() 2025-04-05 10:30:12 +02:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push fixes reverts the multibuffer hash testing as it is buggy. 2025-04-02 09:14:59 -07:00
drivers A set of final cleanups for the timer subsystem: 2025-04-06 08:35:37 -07:00
fs Miscellaneous scheduler fixes/updates: 2025-04-06 10:44:58 -07:00
include A set of final cleanups for the timer subsystem: 2025-04-06 08:35:37 -07:00
init Miscellaneous scheduler fixes/updates: 2025-04-06 10:44:58 -07:00
io_uring io_uring: always do atomic put from iowq 2025-04-03 08:31:57 -06:00
ipc treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
kernel Fix a perf events time accounting bug. 2025-04-06 10:48:12 -07:00
lib Kbuild updates for v6.15 2025-04-05 15:46:50 -07:00
mm Disable SLUB_TINY for build testing 2025-04-06 10:00:04 -07:00
net treewide: Switch/rename to timer_delete[_sync]() 2025-04-05 10:30:12 +02:00
rust Kbuild updates for v6.15 2025-04-05 15:46:50 -07:00
samples treewide: Switch/rename to timer_delete[_sync]() 2025-04-05 10:30:12 +02:00
scripts Disable SLUB_TINY for build testing 2025-04-06 10:00:04 -07:00
security mseal sysmap: kernel config and header change 2025-04-01 15:17:14 -07:00
sound soundwire fix for 6.15-rc1 2025-04-06 12:04:53 -07:00
tools tools/include: make uapi/linux/types.h usable from assembly 2025-04-06 12:55:31 -07:00
usr kbuild: hdrcheck: fix cross build with clang 2025-03-05 04:06:45 +09:00
virt ARM: 2025-03-25 14:22:07 -07:00
.clang-format clang-format: Update with v6.11-rc1's `for_each` macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: give Clippy the minimum supported Rust version 2025-01-10 00:17:25 +01:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: Create intermediate vmlinux build with relocations preserved 2025-03-17 00:29:50 +09:00
.mailmap mailmap: add an entry for Nicolas Schier 2025-04-01 15:20:45 -07:00
.rustfmt.toml
COPYING
CREDITS Including fixes from netfilter. 2025-04-04 09:15:35 -07:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Kbuild updates for v6.15 2025-04-05 15:46:50 -07:00
Makefile Linux 6.15-rc1 2025-04-06 13:11:33 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.