rust: fix the default format for CONFIG_{RUSTC,BINDGEN}_VERSION_TEXT

[ Upstream commit aacf93e87f0d808ef46e621aa56caea336b4433c ]

Another oddity in these config entries is their default value can f

rust: fix the default format for CONFIG_{RUSTC,BINDGEN}_VERSION_TEXT

[ Upstream commit aacf93e87f0d808ef46e621aa56caea336b4433c ]

Another oddity in these config entries is their default value can fall
back to 'n', which is a value for bool or tristate symbols.

The '|| echo n' is an incorrect workaround to avoid the syntax error.
This is not a big deal, as the entry is hidden by 'depends on RUST' in
situations where '$(RUSTC) --version' or '$(BINDGEN) --version' fails.
Anyway, it looks odd.

The default of a string type symbol should be a double-quoted string
literal. Turn it into an empty string when the version command fails.

Fixes: 2f7ab1267dc9 ("Kbuild: add Rust support")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20240727140302.1806011-2-masahiroy@kernel.org
[ Rebased on top of v6.11-rc1. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

rust: suppress error messages from CONFIG_{RUSTC,BINDGEN}_VERSION_TEXT

[ Upstream commit 5ce86c6c861352c9346ebb5c96ed70cb67414aa3 ]

While this is a somewhat unusual case, I encountered odd error me

rust: suppress error messages from CONFIG_{RUSTC,BINDGEN}_VERSION_TEXT

[ Upstream commit 5ce86c6c861352c9346ebb5c96ed70cb67414aa3 ]

While this is a somewhat unusual case, I encountered odd error messages
when I ran Kconfig in a foreign architecture chroot.

$ make allmodconfig
sh: 1: rustc: not found
sh: 1: bindgen: not found
#
# configuration written to .config
#

The successful execution of 'command -v rustc' does not necessarily mean
that 'rustc --version' will succeed.

$ sh -c 'command -v rustc'
/home/masahiro/.cargo/bin/rustc
$ sh -c 'rustc --version'
sh: 1: rustc: not found

Here, 'rustc' is built for x86, and I ran it in an arm64 system.

The current code:

command -v $(RUSTC) >/dev/null 2>&1 && $(RUSTC) --version || echo n

can be turned into:

command -v $(RUSTC) >/dev/null 2>&1 && $(RUSTC) --version 2>/dev/null || echo n

However, I did not understand the necessity of 'command -v $(RUSTC)'.

I simplified it to:

$(RUSTC) --version 2>/dev/null || echo n

Fixes: 2f7ab1267dc9 ("Kbuild: add Rust support")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20240727140302.1806011-1-masahiroy@kernel.org
[ Rebased on top of v6.11-rc1. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

rust: work around `bindgen` 0.69.0 issue

[ Upstream commit 9e98db17837093cb0f4dcfcc3524739d93249c45 ]

`bindgen` 0.69.0 contains a bug: `--version` does not work without
providing a header [1]:

rust: work around `bindgen` 0.69.0 issue

[ Upstream commit 9e98db17837093cb0f4dcfcc3524739d93249c45 ]

`bindgen` 0.69.0 contains a bug: `--version` does not work without
providing a header [1]:

error: the following required arguments were not provided:
<HEADER>

Usage: bindgen <FLAGS> <OPTIONS> <HEADER> -- <CLANG_ARGS>...

Thus, in preparation for supporting several `bindgen` versions, work
around the issue by passing a dummy argument.

Include a comment so that we can remove the workaround in the future.

Link: https://github.com/rust-lang/rust-bindgen/pull/2678 [1]
Reviewed-by: Finn Behrens <me@kloenk.dev>
Tested-by: Benno Lossin <benno.lossin@proton.me>
Tested-by: Andreas Hindborg <a.hindborg@samsung.com>
Link: https://lore.kernel.org/r/20240709160615.998336-9-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Stable-dep-of: 5ce86c6c8613 ("rust: suppress error messages from CONFIG_{RUSTC,BINDGEN}_VERSION_TEXT")
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

rust: SHADOW_CALL_STACK is incompatible with Rust

commit f126745da81783fb1d082e67bf14c6795e489a88 upstream.

When using the shadow call stack sanitizer, all code must be compiled
with the -ffixed-x1

rust: SHADOW_CALL_STACK is incompatible with Rust

commit f126745da81783fb1d082e67bf14c6795e489a88 upstream.

When using the shadow call stack sanitizer, all code must be compiled
with the -ffixed-x18 flag, but this flag is not currently being passed
to Rust. This results in crashes that are extremely difficult to debug.

To ensure that nobody else has to go through the same debugging session
that I had to, prevent configurations that enable both SHADOW_CALL_STACK
and RUST.

It is rather common for people to backport 724a75ac9542 ("arm64: rust:
Enable Rust support for AArch64"), so I recommend applying this fix all
the way back to 6.1.

Cc: stable@vger.kernel.org # 6.1 and later
Fixes: 724a75ac9542 ("arm64: rust: Enable Rust support for AArch64")
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/r/20240729-shadow-call-stack-v4-1-2a664b082ea4@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

rust: make mutually exclusive with CFI_CLANG

commit 8933cf4651e02853ca679be7b2d978dfcdcc5e0c upstream.

On RISC-V and arm64, and presumably x86, if CFI_CLANG is enabled,
loading a rust module will t

rust: make mutually exclusive with CFI_CLANG

commit 8933cf4651e02853ca679be7b2d978dfcdcc5e0c upstream.

On RISC-V and arm64, and presumably x86, if CFI_CLANG is enabled,
loading a rust module will trigger a kernel panic. Support for
sanitisers, including kcfi (CFI_CLANG), is in the works, but for now
they're nightly-only options in rustc. Make RUST depend on !CFI_CLANG
to prevent configuring a kernel without symmetrical support for kfi.

[ Matthew Maurer writes [1]:

This patch is fine by me - the last patch needed for KCFI to be
functional in Rust just landed upstream last night, so we should
revisit this (in the form of enabling it) once we move to
`rustc-1.79.0` or later.

Ramon de C Valle also gave feedback [2] on the status of KCFI for
Rust and created a tracking issue [3] in upstream Rust. - Miguel ]

Fixes: 2f7ab1267dc9 ("Kbuild: add Rust support")
Cc: stable@vger.kernel.org
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/rust-for-linux/CAGSQo024u1gHJgzsO38Xg3c4or+JupoPABQx_+0BLEpPg0cOEA@mail.gmail.com/ [1]
Link: https://lore.kernel.org/rust-for-linux/CAOcBZOS2kPyH0Dm7Fuh4GC3=v7nZhyzBj_-dKu3PfAnrHZvaxg@mail.gmail.com/ [2]
Link: https://github.com/rust-lang/rust/issues/123479 [3]
Link: https://lore.kernel.org/r/20240404-providing-emporium-e652e359c711@spud
[ Added feedback from the list, links, and used Cc for the tag. ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

rust: don't select CONSTRUCTORS

commit 7d49f53af4b988b188d3932deac2c9c80fd7d9ce upstream.

This was originally part of commit 4b9a68f2e59a0 ("rust: add support for
static synchronisation primitives"

rust: don't select CONSTRUCTORS

commit 7d49f53af4b988b188d3932deac2c9c80fd7d9ce upstream.

This was originally part of commit 4b9a68f2e59a0 ("rust: add support for
static synchronisation primitives") from the old Rust branch, which used
module constructors to initialize globals containing various
synchronisation primitives with pin-init. That commit has never been
upstreamed, but the `select CONSTRUCTORS` statement ended up being
included in the patch that initially added Rust support to the Linux
Kernel.

We are not using module constructors, so let's remove the select.

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Cc: stable@vger.kernel.org
Fixes: 2f7ab1267dc9 ("Kbuild: add Rust support")
Link: https://lore.kernel.org/r/20240308-constructors-v1-1-4c811342391c@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

init/Kconfig: lower GCC version check for -Warray-bounds

commit 3e00f5802fabf2f504070a591b14b648523ede13 upstream.

We continue to see false positives from -Warray-bounds even in GCC 10,
which is ge

init/Kconfig: lower GCC version check for -Warray-bounds

commit 3e00f5802fabf2f504070a591b14b648523ede13 upstream.

We continue to see false positives from -Warray-bounds even in GCC 10,
which is getting reported in a few places[1] still:

security/security.c:811:2: warning: `memcpy' offset 32 is out of the bounds [0, 0] [-Warray-bounds]

Lower the GCC version check from 11 to 10.

Link: https://lkml.kernel.org/r/20240223170824.work.768-kees@kernel.org
Reported-by: Lu Yao <yaolu@kylinos.cn>
Closes: https://lore.kernel.org/lkml/20240117014541.8887-1-yaolu@kylinos.cn/
Link: https://lore.kernel.org/linux-next/65d84438.620a0220.7d171.81a7@mx.google.com [1]
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Paul Moore <paul@paul-moore.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Marc Aurèle La France <tsi@tuyoix.net>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

update workarounds for gcc "asm goto" issue

commit 68fb3ca0e408e00db1c3f8fccdfa19e274c033be upstream.

In commit 4356e9f841f7 ("work around gcc bugs with 'asm goto' with
outputs") I did the gcc work

update workarounds for gcc "asm goto" issue

commit 68fb3ca0e408e00db1c3f8fccdfa19e274c033be upstream.

In commit 4356e9f841f7 ("work around gcc bugs with 'asm goto' with
outputs") I did the gcc workaround unconditionally, because the cause of
the bad code generation wasn't entirely clear.

In the meantime, Jakub Jelinek debugged the issue, and has come up with
a fix in gcc [2], which also got backported to the still maintained
branches of gcc-11, gcc-12 and gcc-13.

Note that while the fix technically wasn't in the original gcc-14
branch, Jakub says:

"while it is true that no GCC 14 snapshots until today (or whenever the
fix will be committed) have the fix, for GCC trunk it is up to the
distros to use the latest snapshot if they use it at all and would
allow better testing of the kernel code without the workaround, so
that if there are other issues they won't be discovered years later.
Most userland code doesn't actually use asm goto with outputs..."

so we will consider gcc-14 to be fixed - if somebody is using gcc
snapshots of the gcc-14 before the fix, they should upgrade.

Note that while the bug goes back to gcc-11, in practice other gcc
changes seem to have effectively hidden it since gcc-12.1 as per a
bisect by Jakub. So even a gcc-14 snapshot without the fix likely
doesn't show actual problems.

Also, make the default 'asm_goto_output()' macro mark the asm as
volatile by hand, because of an unrelated gcc issue [1] where it doesn't
match the documented behavior ("asm goto is always volatile").

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103979 [1]
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921 [2]
Link: https://lore.kernel.org/all/20240208220604.140859-1-seanjc@google.com/
Requested-by: Jakub Jelinek <jakub@redhat.com>
Cc: Uros Bizjak <ubizjak@gmail.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Andrew Pinski <quic_apinski@quicinc.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

treewide: drop CONFIG_EMBEDDED

There is only one Kconfig user of CONFIG_EMBEDDED and it can be switched
to EXPERT or "if !ARCH_MULTIPLATFORM" (suggested by Arnd).

Link: https://lkml.kernel.org/r/20

treewide: drop CONFIG_EMBEDDED

There is only one Kconfig user of CONFIG_EMBEDDED and it can be switched
to EXPERT or "if !ARCH_MULTIPLATFORM" (suggested by Arnd).

Link: https://lkml.kernel.org/r/20230816055010.31534-1-rdunlap@infradead.org
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com> [RISC-V]
Acked-by: Greg Ungerer <gerg@linux-m68k.org>
Acked-by: Jason A. Donenfeld <Jason@zx2c4.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc]
Cc: Russell King <linux@armlinux.org.uk>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

show more ...

kexec: consolidate kexec and crash options into kernel/Kconfig.kexec

Patch series "refactor Kconfig to consolidate KEXEC and CRASH options", v6.

The Kconfig is refactored to consolidate KEXEC and C

kexec: consolidate kexec and crash options into kernel/Kconfig.kexec

Patch series "refactor Kconfig to consolidate KEXEC and CRASH options", v6.

The Kconfig is refactored to consolidate KEXEC and CRASH options from
various arch/<arch>/Kconfig files into new file kernel/Kconfig.kexec.

The Kconfig.kexec is now a submenu titled "Kexec and crash features"
located under "General Setup".

The following options are impacted:

- KEXEC
- KEXEC_FILE
- KEXEC_SIG
- KEXEC_SIG_FORCE
- KEXEC_IMAGE_VERIFY_SIG
- KEXEC_BZIMAGE_VERIFY_SIG
- KEXEC_JUMP
- CRASH_DUMP

Over time, these options have been copied between Kconfig files and
are very similar to one another, but with slight differences.

The following architectures are impacted by the refactor (because of
use of one or more KEXEC/CRASH options):

- arm
- arm64
- ia64
- loongarch
- m68k
- mips
- parisc
- powerpc
- riscv
- s390
- sh
- x86

More information:

In the patch series "crash: Kernel handling of CPU and memory hot
un/plug"

https://lore.kernel.org/lkml/20230503224145.7405-1-eric.devolder@oracle.com/

the new kernel feature introduces the config option CRASH_HOTPLUG.

In reviewing, Thomas Gleixner requested that the new config option
not be placed in x86 Kconfig. Rather the option needs a generic/common
home. To Thomas' point, the KEXEC and CRASH options have largely been
duplicated in the various arch/<arch>/Kconfig files, with minor
differences. This kind of proliferation is to be avoid/stopped.

https://lore.kernel.org/lkml/875y91yv63.ffs@tglx/

To that end, I have refactored the arch Kconfigs so as to consolidate
the various KEXEC and CRASH options. Generally speaking, this work has
the following themes:

- KEXEC and CRASH options are moved into new file kernel/Kconfig.kexec
- These items from arch/Kconfig:
CRASH_CORE KEXEC_CORE KEXEC_ELF HAVE_IMA_KEXEC
- These items from arch/x86/Kconfig form the common options:
KEXEC KEXEC_FILE KEXEC_SIG KEXEC_SIG_FORCE
KEXEC_BZIMAGE_VERIFY_SIG KEXEC_JUMP CRASH_DUMP
- These items from arch/arm64/Kconfig form the common options:
KEXEC_IMAGE_VERIFY_SIG
- The crash hotplug series appends CRASH_HOTPLUG to Kconfig.kexec
- The Kconfig.kexec is now a submenu titled "Kexec and crash features"
and is now listed in "General Setup" submenu from init/Kconfig.
- To control the common options, each has a new ARCH_SUPPORTS_<option>
option. These gateway options determine whether the common options
options are valid for the architecture.
- To account for the slight differences in the original architecture
coding of the common options, each now has a corresponding
ARCH_SELECTS_<option> which are used to elicit the same side effects
as the original arch/<arch>/Kconfig files for KEXEC and CRASH options.

An example, 'make menuconfig' illustrating the submenu:

> General setup > Kexec and crash features
[*] Enable kexec system call
[*] Enable kexec file based system call
[*] Verify kernel signature during kexec_file_load() syscall
[ ] Require a valid signature in kexec_file_load() syscall
[ ] Enable bzImage signature verification support
[*] kexec jump
[*] kernel crash dumps
[*] Update the crash elfcorehdr on system configuration changes

In the process of consolidating the common options, I encountered
slight differences in the coding of these options in several of the
architectures. As a result, I settled on the following solution:

- Each of the common options has a 'depends on ARCH_SUPPORTS_<option>'
statement. For example, the KEXEC_FILE option has a 'depends on
ARCH_SUPPORTS_KEXEC_FILE' statement.

This approach is needed on all common options so as to prevent
options from appearing for architectures which previously did
not allow/enable them. For example, arm supports KEXEC but not
KEXEC_FILE. The arch/arm/Kconfig does not provide
ARCH_SUPPORTS_KEXEC_FILE and so KEXEC_FILE and related options
are not available to arm.

- The boolean ARCH_SUPPORTS_<option> in effect allows the arch to
determine when the feature is allowed. Archs which don't have the
feature simply do not provide the corresponding ARCH_SUPPORTS_<option>.
For each arch, where there previously were KEXEC and/or CRASH
options, these have been replaced with the corresponding boolean
ARCH_SUPPORTS_<option>, and an appropriate def_bool statement.

For example, if the arch supports KEXEC_FILE, then the
ARCH_SUPPORTS_KEXEC_FILE simply has a 'def_bool y'. This permits
the KEXEC_FILE option to be available.

If the arch has a 'depends on' statement in its original coding
of the option, then that expression becomes part of the def_bool
expression. For example, arm64 had:

config KEXEC
depends on PM_SLEEP_SMP

and in this solution, this converts to:

config ARCH_SUPPORTS_KEXEC
def_bool PM_SLEEP_SMP


- In order to account for the architecture differences in the
coding for the common options, the ARCH_SELECTS_<option> in the
arch/<arch>/Kconfig is used. This option has a 'depends on
<option>' statement to couple it to the main option, and from
there can insert the differences from the common option and the
arch original coding of that option.

For example, a few archs enable CRYPTO and CRYTPO_SHA256 for
KEXEC_FILE. These require a ARCH_SELECTS_KEXEC_FILE and
'select CRYPTO' and 'select CRYPTO_SHA256' statements.

Illustrating the option relationships:

For each of the common KEXEC and CRASH options:
ARCH_SUPPORTS_<option> <- <option> <- ARCH_SELECTS_<option>

<option> # in Kconfig.kexec
ARCH_SUPPORTS_<option> # in arch/<arch>/Kconfig, as needed
ARCH_SELECTS_<option> # in arch/<arch>/Kconfig, as needed


For example, KEXEC:
ARCH_SUPPORTS_KEXEC <- KEXEC <- ARCH_SELECTS_KEXEC

KEXEC # in Kconfig.kexec
ARCH_SUPPORTS_KEXEC # in arch/<arch>/Kconfig, as needed
ARCH_SELECTS_KEXEC # in arch/<arch>/Kconfig, as needed


To summarize, the ARCH_SUPPORTS_<option> permits the <option> to be
enabled, and the ARCH_SELECTS_<option> handles side effects (ie.
select statements).

Examples:
A few examples to show the new strategy in action:

===== x86 (minus the help section) =====
Original:
config KEXEC
bool "kexec system call"
select KEXEC_CORE

config KEXEC_FILE
bool "kexec file based system call"
select KEXEC_CORE
select HAVE_IMA_KEXEC if IMA
depends on X86_64
depends on CRYPTO=y
depends on CRYPTO_SHA256=y

config ARCH_HAS_KEXEC_PURGATORY
def_bool KEXEC_FILE

config KEXEC_SIG
bool "Verify kernel signature during kexec_file_load() syscall"
depends on KEXEC_FILE

config KEXEC_SIG_FORCE
bool "Require a valid signature in kexec_file_load() syscall"
depends on KEXEC_SIG

config KEXEC_BZIMAGE_VERIFY_SIG
bool "Enable bzImage signature verification support"
depends on KEXEC_SIG
depends on SIGNED_PE_FILE_VERIFICATION
select SYSTEM_TRUSTED_KEYRING

config CRASH_DUMP
bool "kernel crash dumps"
depends on X86_64 || (X86_32 && HIGHMEM)

config KEXEC_JUMP
bool "kexec jump"
depends on KEXEC && HIBERNATION
help

becomes...
New:
config ARCH_SUPPORTS_KEXEC
def_bool y

config ARCH_SUPPORTS_KEXEC_FILE
def_bool X86_64 && CRYPTO && CRYPTO_SHA256

config ARCH_SELECTS_KEXEC_FILE
def_bool y
depends on KEXEC_FILE
select HAVE_IMA_KEXEC if IMA

config ARCH_SUPPORTS_KEXEC_PURGATORY
def_bool KEXEC_FILE

config ARCH_SUPPORTS_KEXEC_SIG
def_bool y

config ARCH_SUPPORTS_KEXEC_SIG_FORCE
def_bool y

config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
def_bool y

config ARCH_SUPPORTS_KEXEC_JUMP
def_bool y

config ARCH_SUPPORTS_CRASH_DUMP
def_bool X86_64 || (X86_32 && HIGHMEM)


===== powerpc (minus the help section) =====
Original:
config KEXEC
bool "kexec system call"
depends on PPC_BOOK3S || PPC_E500 || (44x && !SMP)
select KEXEC_CORE

config KEXEC_FILE
bool "kexec file based system call"
select KEXEC_CORE
select HAVE_IMA_KEXEC if IMA
select KEXEC_ELF
depends on PPC64
depends on CRYPTO=y
depends on CRYPTO_SHA256=y

config ARCH_HAS_KEXEC_PURGATORY
def_bool KEXEC_FILE

config CRASH_DUMP
bool "Build a dump capture kernel"
depends on PPC64 || PPC_BOOK3S_32 || PPC_85xx || (44x && !SMP)
select RELOCATABLE if PPC64 || 44x || PPC_85xx

becomes...
New:
config ARCH_SUPPORTS_KEXEC
def_bool PPC_BOOK3S || PPC_E500 || (44x && !SMP)

config ARCH_SUPPORTS_KEXEC_FILE
def_bool PPC64 && CRYPTO=y && CRYPTO_SHA256=y

config ARCH_SUPPORTS_KEXEC_PURGATORY
def_bool KEXEC_FILE

config ARCH_SELECTS_KEXEC_FILE
def_bool y
depends on KEXEC_FILE
select KEXEC_ELF
select HAVE_IMA_KEXEC if IMA

config ARCH_SUPPORTS_CRASH_DUMP
def_bool PPC64 || PPC_BOOK3S_32 || PPC_85xx || (44x && !SMP)

config ARCH_SELECTS_CRASH_DUMP
def_bool y
depends on CRASH_DUMP
select RELOCATABLE if PPC64 || 44x || PPC_85xx


Testing Approach and Results

There are 388 config files in the arch/<arch>/configs directories.
For each of these config files, a .config is generated both before and
after this Kconfig series, and checked for equivalence. This approach
allows for a rather rapid check of all architectures and a wide
variety of configs wrt/ KEXEC and CRASH, and avoids requiring
compiling for all architectures and running kernels and run-time
testing.

For each config file, the olddefconfig, allnoconfig and allyesconfig
targets are utilized. In testing the randconfig has revealed problems
as well, but is not used in the before and after equivalence check
since one can not generate the "same" .config for before and after,
even if using the same KCONFIG_SEED since the option list is
different.

As such, the following script steps compare the before and after
of 'make olddefconfig'. The new symbols introduced by this series
are filtered out, but otherwise the config files are PASS only if
they were equivalent, and FAIL otherwise.

The script performs the test by doing the following:

# Obtain the "golden" .config output for given config file
# Reset test sandbox
git checkout master
git branch -D test_Kconfig
git checkout -B test_Kconfig master
make distclean
# Write out updated config
cp -f <config file> .config
make ARCH=<arch> olddefconfig
# Track each item in .config, LHSB is "golden"
scoreboard .config

# Obtain the "changed" .config output for given config file
# Reset test sandbox
make distclean
# Apply this Kconfig series
git am <this Kconfig series>
# Write out updated config
cp -f <config file> .config
make ARCH=<arch> olddefconfig
# Track each item in .config, RHSB is "changed"
scoreboard .config

# Determine test result
# Filter-out new symbols introduced by this series
# Filter-out symbol=n which not in either scoreboard
# Compare LHSB "golden" and RHSB "changed" scoreboards and issue PASS/FAIL

The script was instrumental during the refactoring of Kconfig as it
continually revealed problems. The end result being that the solution
presented in this series passes all configs as checked by the script,
with the following exceptions:

- arch/ia64/configs/zx1_config with olddefconfig
This config file has:
# CONFIG_KEXEC is not set
CONFIG_CRASH_DUMP=y
and this refactor now couples KEXEC to CRASH_DUMP, so it is not
possible to enable CRASH_DUMP without KEXEC.

- arch/sh/configs/* with allyesconfig
The arch/sh/Kconfig codes CRASH_DUMP as dependent upon BROKEN_ON_MMU
(which clearly is not meant to be set). This symbol is not provided
but with the allyesconfig it is set to yes which enables CRASH_DUMP.
But KEXEC is coded as dependent upon MMU, and is set to no in
arch/sh/mm/Kconfig, so KEXEC is not enabled.
This refactor now couples KEXEC to CRASH_DUMP, so it is not
possible to enable CRASH_DUMP without KEXEC.

While the above exceptions are not equivalent to their original,
the config file produced is valid (and in fact better wrt/ CRASH_DUMP
handling).


This patch (of 14)

The config options for kexec and crash features are consolidated
into new file kernel/Kconfig.kexec. Under the "General Setup" submenu
is a new submenu "Kexec and crash handling". All the kexec and
crash options that were once in the arch-dependent submenu "Processor
type and features" are now consolidated in the new submenu.

The following options are impacted:

- KEXEC
- KEXEC_FILE
- KEXEC_SIG
- KEXEC_SIG_FORCE
- KEXEC_BZIMAGE_VERIFY_SIG
- KEXEC_JUMP
- CRASH_DUMP

The three main options are KEXEC, KEXEC_FILE and CRASH_DUMP.

Architectures specify support of certain KEXEC and CRASH features with
similarly named new ARCH_SUPPORTS_<option> config options.

Architectures can utilize the new ARCH_SELECTS_<option> config
options to specify additional components when <option> is enabled.

To summarize, the ARCH_SUPPORTS_<option> permits the <option> to be
enabled, and the ARCH_SELECTS_<option> handles side effects (ie.
select statements).

Link: https://lkml.kernel.org/r/20230712161545.87870-1-eric.devolder@oracle.com
Link: https://lkml.kernel.org/r/20230712161545.87870-2-eric.devolder@oracle.com
Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Cc. "H. Peter Anvin" <hpa@zytor.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com> # for x86
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Juerg Haefliger <juerg.haefliger@canonical.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Marc Aurèle La France <tsi@tuyoix.net>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Sebastian Reichel <sebastian.reichel@collabora.com>
Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Xin Li <xin3.li@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

show more ...

sched/psi: Select KERNFS as needed

Users of KERNFS should select it to enforce its being built, so
do this to prevent a build error.

In file included from ../kernel/sched/build_utility.c:97:
../ker

sched/psi: Select KERNFS as needed

Users of KERNFS should select it to enforce its being built, so
do this to prevent a build error.

In file included from ../kernel/sched/build_utility.c:97:
../kernel/sched/psi.c: In function 'psi_trigger_poll':
../kernel/sched/psi.c:1479:17: error: implicit declaration of function 'kernfs_generic_poll' [-Werror=implicit-function-declaration]
1479 | kernfs_generic_poll(t->of, wait);

Fixes: aff037078eca ("sched/psi: use kernfs polling functions for PSI trigger polling")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Suren Baghdasaryan <surenb@google.com>
Link: lore.kernel.org/r/202307310732.r65EQFY0-lkp@intel.com

show more ...

cachestat: implement cachestat syscall

There is currently no good way to query the page cache state of large file
sets and directory trees. There is mincore(), but it scales poorly: the
kernel writ

cachestat: implement cachestat syscall

There is currently no good way to query the page cache state of large file
sets and directory trees. There is mincore(), but it scales poorly: the
kernel writes out a lot of bitmap data that userspace has to aggregate,
when the user really doesn not care about per-page information in that
case. The user also needs to mmap and unmap each file as it goes along,
which can be quite slow as well.

Some use cases where this information could come in handy:
* Allowing database to decide whether to perform an index scan or
direct table queries based on the in-memory cache state of the
index.
* Visibility into the writeback algorithm, for performance issues
diagnostic.
* Workload-aware writeback pacing: estimating IO fulfilled by page
cache (and IO to be done) within a range of a file, allowing for
more frequent syncing when and where there is IO capacity, and
batching when there is not.
* Computing memory usage of large files/directory trees, analogous to
the du tool for disk usage.

More information about these use cases could be found in the following
thread:

https://lore.kernel.org/lkml/20230315170934.GA97793@cmpxchg.org/

This patch implements a new syscall that queries cache state of a file and
summarizes the number of cached pages, number of dirty pages, number of
pages marked for writeback, number of (recently) evicted pages, etc. in a
given range. Currently, the syscall is only wired in for x86
architecture.

NAME
cachestat - query the page cache statistics of a file.

SYNOPSIS
#include <sys/mman.h>

struct cachestat_range {
__u64 off;
__u64 len;
};

struct cachestat {
__u64 nr_cache;
__u64 nr_dirty;
__u64 nr_writeback;
__u64 nr_evicted;
__u64 nr_recently_evicted;
};

int cachestat(unsigned int fd, struct cachestat_range *cstat_range,
struct cachestat *cstat, unsigned int flags);

DESCRIPTION
cachestat() queries the number of cached pages, number of dirty
pages, number of pages marked for writeback, number of evicted
pages, number of recently evicted pages, in the bytes range given by
`off` and `len`.

An evicted page is a page that is previously in the page cache but
has been evicted since. A page is recently evicted if its last
eviction was recent enough that its reentry to the cache would
indicate that it is actively being used by the system, and that
there is memory pressure on the system.

These values are returned in a cachestat struct, whose address is
given by the `cstat` argument.

The `off` and `len` arguments must be non-negative integers. If
`len` > 0, the queried range is [`off`, `off` + `len`]. If `len` ==
0, we will query in the range from `off` to the end of the file.

The `flags` argument is unused for now, but is included for future
extensibility. User should pass 0 (i.e no flag specified).

Currently, hugetlbfs is not supported.

Because the status of a page can change after cachestat() checks it
but before it returns to the application, the returned values may
contain stale information.

RETURN VALUE
On success, cachestat returns 0. On error, -1 is returned, and errno
is set to indicate the error.

ERRORS
EFAULT cstat or cstat_args points to an invalid address.

EINVAL invalid flags.

EBADF invalid file descriptor.

EOPNOTSUPP file descriptor is of a hugetlbfs file

[nphamcs@gmail.com: replace rounddown logic with the existing helper]
Link: https://lkml.kernel.org/r/20230504022044.3675469-1-nphamcs@gmail.com
Link: https://lkml.kernel.org/r/20230503013608.2431726-3-nphamcs@gmail.com
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

show more ...

gcc: disable '-Warray-bounds' for gcc-13 too

We started disabling '-Warray-bounds' for gcc-12 originally on s390,
because it resulted in some warnings that weren't realistically fixable
(commit 8b20

gcc: disable '-Warray-bounds' for gcc-13 too

We started disabling '-Warray-bounds' for gcc-12 originally on s390,
because it resulted in some warnings that weren't realistically fixable
(commit 8b202ee21839: "s390: disable -Warray-bounds").

That s390-specific issue was then found to be less common elsewhere, but
generic (see f0be87c42cbd: "gcc-12: disable '-Warray-bounds' universally
for now"), and then later expanded the version check was expanded to
gcc-11 (5a41237ad1d4: "gcc: disable -Warray-bounds for gcc-11 too").

And it turns out that I was much too optimistic in thinking that it's
all going to go away, and here we are with gcc-13 showing all the same
issues. So instead of expanding this one version at a time, let's just
disable it for gcc-11+, and put an end limit to it only when we actually
find a solution.

Yes, I'm sure some of this is because the kernel just does odd things
(like our "container_of()" use, but also knowingly playing games with
things like linker tables and array layouts).

And yes, some of the warnings are likely signs of real bugs, but when
there are hundreds of false positives, that doesn't really help.

Oh well.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

mm/slob: remove CONFIG_SLOB

Remove SLOB from Kconfig and Makefile. Everything under #ifdef
CONFIG_SLOB, and mm/slob.c is now dead code.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Hye

mm/slob: remove CONFIG_SLOB

Remove SLOB from Kconfig and Makefile. Everything under #ifdef
CONFIG_SLOB, and mm/slob.c is now dead code.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>

show more ...

Remove orphaned CONFIG_PRINTK_SAFE_LOG_BUF_SHIFT

After the commit 93d102f094be9beab2 ("printk: remove safe buffers"),
CONFIG_PRINTK_SAFE_LOG_BUF_SHIFT is no longer useful. Remove it.

Signed-off-by

Remove orphaned CONFIG_PRINTK_SAFE_LOG_BUF_SHIFT

After the commit 93d102f094be9beab2 ("printk: remove safe buffers"),
CONFIG_PRINTK_SAFE_LOG_BUF_SHIFT is no longer useful. Remove it.

Signed-off-by: Marc Aurèle La France <tsi@tuyoix.net>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
[pmladek@suse.cz: Cleaned up the commit message.]
Signed-off-by: Petr Mladek <pmladek@suse.com>
Fixes: 93d102f094be9beab ("printk: remove safe buffers")
Link: https://lore.kernel.org/r/5c19e248-1b6b-330c-7c4c-a824688daefe@tuyoix.net

show more ...

driver core: remove CONFIG_SYSFS_DEPRECATED and CONFIG_SYSFS_DEPRECATED_V2

CONFIG_SYSFS_DEPRECATED was added in commit 88a22c985e35
("CONFIG_SYSFS_DEPRECATED") in 2006 to allow systems with older ve

driver core: remove CONFIG_SYSFS_DEPRECATED and CONFIG_SYSFS_DEPRECATED_V2

CONFIG_SYSFS_DEPRECATED was added in commit 88a22c985e35
("CONFIG_SYSFS_DEPRECATED") in 2006 to allow systems with older versions
of some tools (i.e. Fedora 3's version of udev) to boot properly. Four
years later, in 2010, the option was attempted to be removed as most of
userspace should have been fixed up properly by then, but some kernel
developers clung to those old systems and refused to update, so we added
CONFIG_SYSFS_DEPRECATED_V2 in commit e52eec13cd6b ("SYSFS: Allow boot
time switching between deprecated and modern sysfs layout") to allow
them to continue to boot properly, and we allowed a boot time parameter
to be used to switch back to the old format if needed.

Over time, the logic that was covered under these config options was
slowly removed from individual driver subsystems successfully, removed,
and the only thing that is now left in the kernel are some changes in
the block layer's representation in sysfs where real directories are
used instead of symlinks like normal.

Because the original changes were done to userspace tools in 2006, and
all distros that use those tools are long end-of-life, and older
non-udev-based systems do not care about the block layer's sysfs
representation, it is time to finally remove this old logic and the
config entries from the kernel.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: linux-block@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Acked-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20230223073326.2073220-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

bootconfig: Default BOOT_CONFIG_FORCE to y if BOOT_CONFIG_EMBED

When a kernel is built with CONFIG_BOOT_CONFIG_EMBED=y, the intention
will normally be to unconditionally provide the specified kernel

bootconfig: Default BOOT_CONFIG_FORCE to y if BOOT_CONFIG_EMBED

When a kernel is built with CONFIG_BOOT_CONFIG_EMBED=y, the intention
will normally be to unconditionally provide the specified kernel-boot
arguments to the kernel, as opposed to requiring a separately provided
bootconfig parameter. Therefore, make the BOOT_CONFIG_FORCE Kconfig
option default to y in kernels built with CONFIG_BOOT_CONFIG_EMBED=y.

The old semantics may be obtained by manually overriding this default.

Link: https://lore.kernel.org/all/20230107162202.GA4028633@paulmck-ThinkPad-P17-Gen-1/

Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

show more ...

Allow forcing unconditional bootconfig processing

The BOOT_CONFIG family of Kconfig options allows a bootconfig file
containing kernel boot parameters to be embedded into an initrd or into
the kerne

Allow forcing unconditional bootconfig processing

The BOOT_CONFIG family of Kconfig options allows a bootconfig file
containing kernel boot parameters to be embedded into an initrd or into
the kernel itself. This can be extremely useful when deploying kernels
in cases where some of the boot parameters depend on the kernel version
rather than on the server hardware, firmware, or workload.

Unfortunately, the "bootconfig" kernel parameter must be specified in
order to cause the kernel to look for the embedded bootconfig file,
and it clearly does not help to embed this "bootconfig" kernel parameter
into that file.

Therefore, provide a new BOOT_CONFIG_FORCE Kconfig option that causes the
kernel to act as if the "bootconfig" kernel parameter had been specified.
In other words, kernels built with CONFIG_BOOT_CONFIG_FORCE=y will look
for the embedded bootconfig file even when the "bootconfig" kernel
parameter is omitted. This permits kernel-version-dependent kernel
boot parameters to be embedded into the kernel image without the need to
(for example) update large numbers of boot loaders.

Link: https://lore.kernel.org/all/20230105005838.GA1772817@paulmck-ThinkPad-P17-Gen-1/

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <linux-doc@vger.kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

show more ...

init: Remove "select SRCU"

Now that the SRCU Kconfig option is unconditionally selected, there is
no longer any point in selecting it. Therefore, remove the "select SRCU"
Kconfig statements.

Signe

init: Remove "select SRCU"

Now that the SRCU Kconfig option is unconditionally selected, there is
no longer any point in selecting it. Therefore, remove the "select SRCU"
Kconfig statements.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: John Ogness <john.ogness@linutronix.de>

show more ...

scripts: remove bin2c

Commit 80f8be7af03f ("tomoyo: Omit use of bin2c") removed the last
use of bin2c.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fja

scripts: remove bin2c

Commit 80f8be7af03f ("tomoyo: Omit use of bin2c") removed the last
use of bin2c.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com>

show more ...

btf, scripts: Exclude Rust CUs with pahole

Version 1.24 of pahole has the capability to exclude compilation units (CUs)
of specific languages [1] [2]. Rust, as of writing, is not currently supported

btf, scripts: Exclude Rust CUs with pahole

Version 1.24 of pahole has the capability to exclude compilation units (CUs)
of specific languages [1] [2]. Rust, as of writing, is not currently supported
by pahole and if it's used with a build that has BTF debugging enabled it
results in malformed kernel and module binaries [3]. So it's better for pahole
to exclude Rust CUs until support for it arrives.

Co-developed-by: Eric Curtin <ecurtin@redhat.com>
Signed-off-by: Eric Curtin <ecurtin@redhat.com>
Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Eric Curtin <ecurtin@redhat.com>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?id=49358dfe2aaae4e90b072332c3e324019826783f [1]
Link: https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?id=8ee363790b7437283c53090a85a9fec2f0b0fbc4 [2]
Link: https://github.com/Rust-for-Linux/linux/issues/735 [3]
Link: https://lore.kernel.org/bpf/20230111152050.559334-1-yakoyoku@gmail.com

show more ...

init/Kconfig: fix typo (usafe -> unsafe)

Fix the help text for the PRINTK_SAFE_LOG_BUF_SHIFT setting.

Link: https://lkml.kernel.org/r/20230109201837.23873-1-eliasfleckenstein@web.de
Signed-off-by:

init/Kconfig: fix typo (usafe -> unsafe)

Fix the help text for the PRINTK_SAFE_LOG_BUF_SHIFT setting.

Link: https://lkml.kernel.org/r/20230109201837.23873-1-eliasfleckenstein@web.de
Signed-off-by: Lizzy Fleckenstein <eliasfleckenstein@web.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

show more ...

init/Kconfig: fix LOCALVERSION_AUTO help text

It was never guaranteed to be exactly eight, but since commit
548b8b5168c9 ("scripts/setlocalversion: make git describe output more
reliable"), it has b

init/Kconfig: fix LOCALVERSION_AUTO help text

It was never guaranteed to be exactly eight, but since commit
548b8b5168c9 ("scripts/setlocalversion: make git describe output more
reliable"), it has been exactly 12.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

show more ...

gcc: disable -Warray-bounds for gcc-11 too

We had already disabled this warning for gcc-12 due to bugs in the value
range analysis, but it turns out we end up having some similar problems
with gcc-1

gcc: disable -Warray-bounds for gcc-11 too

We had already disabled this warning for gcc-12 due to bugs in the value
range analysis, but it turns out we end up having some similar problems
with gcc-11.3 too, so let's disable it there too.

Older gcc versions end up being increasingly less relevant, and
hopefully clang and newer version of gcc (ie gcc-13) end up working
reliably enough that we still get the build coverage even when we
disable this for some versions.

Link: https://lore.kernel.org/all/20221227002941.GA2691687@roeck-us.net/
Link: https://lore.kernel.org/all/D8BDBF66-E44C-45D4-9758-BAAA4F0C1998@kernel.org/
Cc: Kees Cook <kees@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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sched: Introduce per-memory-map concurrency ID

This feature allows the scheduler to expose a per-memory map concurrency
ID to user-space. This concurrency ID is within the possible cpus range,
and i

sched: Introduce per-memory-map concurrency ID

This feature allows the scheduler to expose a per-memory map concurrency
ID to user-space. This concurrency ID is within the possible cpus range,
and is temporarily (and uniquely) assigned while threads are actively
running within a memory map. If a memory map has fewer threads than
cores, or is limited to run on few cores concurrently through sched
affinity or cgroup cpusets, the concurrency IDs will be values close
to 0, thus allowing efficient use of user-space memory for per-cpu
data structures.

This feature is meant to be exposed by a new rseq thread area field.

The primary purpose of this feature is to do the heavy-lifting needed
by memory allocators to allow them to use per-cpu data structures
efficiently in the following situations:

- Single-threaded applications,
- Multi-threaded applications on large systems (many cores) with limited
cpu affinity mask,
- Multi-threaded applications on large systems (many cores) with
restricted cgroup cpuset per container.

One of the key concern from scheduler maintainers is the overhead
associated with additional spin locks or atomic operations in the
scheduler fast-path. This is why the following optimization is
implemented.

On context switch between threads belonging to the same memory map,
transfer the mm_cid from prev to next without any atomic ops. This
takes care of use-cases involving frequent context switch between
threads belonging to the same memory map.

Additional optimizations can be done if the spin locks added when
context switching between threads belonging to different memory maps end
up being a performance bottleneck. Those are left out of this patch
though. A performance impact would have to be clearly demonstrated to
justify the added complexity.

The credit goes to Paul Turner (Google) for the original virtual cpu id
idea. This feature is implemented based on the discussions with Paul
Turner and Peter Oskolkov (Google), but I took the liberty to implement
scheduler fast-path optimizations and my own NUMA-awareness scheme. The
rumor has it that Google have been running a rseq vcpu_id extension
internally in production for a year. The tcmalloc source code indeed has
comments hinting at a vcpu_id prototype extension to the rseq system
call [1].

The following benchmarks do not show any significant overhead added to
the scheduler context switch by this feature:

* perf bench sched messaging (process)

Baseline: 86.5±0.3 ms
With mm_cid: 86.7±2.6 ms

* perf bench sched messaging (threaded)

Baseline: 84.3±3.0 ms
With mm_cid: 84.7±2.6 ms

* hackbench (process)

Baseline: 82.9±2.7 ms
With mm_cid: 82.9±2.9 ms

* hackbench (threaded)

Baseline: 85.2±2.6 ms
With mm_cid: 84.4±2.9 ms

[1] https://github.com/google/tcmalloc/blob/master/tcmalloc/internal/linux_syscall_support.h#L26

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221122203932.231377-8-mathieu.desnoyers@efficios.com

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