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Christian Brauner 5334fc2807
Merge patch series "Allow inlining C helpers into Rust when using LTO"
Alice Ryhl <aliceryhl@google.com> says:

This patch series adds __rust_helper to every single rust helper.

These changes were generated by adding __rust_helper and running
ClangFormat. Unrelated formatting changes were removed manually.

Why is __rust_helper needed?
============================

Currently, C helpers cannot be inlined into Rust even when using LTO
because LLVM detects slightly different options on the codegen units.

* LLVM doesn't want to inline functions compiled with
  `-fno-delete-null-pointer-checks` with code compiled without. The C
  CGUs all have this enabled and Rust CGUs don't. Inlining is okay since
  this is one of the hardening features that does not change the ABI,
  and we shouldn't have null pointer dereferences in these helpers.

* LLVM doesn't want to inline functions with different list of builtins. C
  side has `-fno-builtin-wcslen`; `wcslen` is not a Rust builtin, so
  they should be compatible, but LLVM does not perform inlining due to
  attributes mismatch.

* clang and Rust doesn't have the exact target string. Clang generates
  `+cmov,+cx8,+fxsr` but Rust doesn't enable them (in fact, Rust will
  complain if `-Ctarget-feature=+cmov,+cx8,+fxsr` is used). x86-64
  always enable these features, so they are in fact the same target
  string, but LLVM doesn't understand this and so inlining is inhibited.
  This can be bypassed with `--ignore-tti-inline-compatible`, but this
  is a hidden option.

(This analysis was written by Gary Guo.)

How is this fixed?
==================

To fix this we need to add __always_inline to all helpers when compiling
with LTO. However, it should not be added when running bindgen as
bindgen will ignore functions marked inline. To achieve this, we are
using a #define called __rust_helper that is defined differently
depending on whether bindgen is running or not.

Note that __rust_helper is currently always #defined to nothing.
Changing it to __always_inline will happen separately in another patch
series.

* patches from https://patch.msgid.link/20251202-define-rust-helper-v1-0-a2e13cbc17a6@google.com:
  rust: poll: add __rust_helper to helpers
  rust: pid_namespace: add __rust_helper to helpers
  rust: fs: add __rust_helper to helpers

Link: https://patch.msgid.link/20251202-define-rust-helper-v1-0-a2e13cbc17a6@google.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
History 2025-12-15 14:13:04 +01:00
arch Misc fixes: 2025-12-14 06:10:35 +12:00
block block-6.19-20251211 2025-12-12 22:04:18 +12:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto Networking changes for 6.19. 2025-12-03 17:24:33 -08:00
Documentation Misc fixes: 2025-12-14 06:07:09 +12:00
drivers SCSI misc on 20251214 2025-12-14 15:35:35 +12:00
fs We have a patch that adds an initial set of tracepoints to the MDS 2025-12-14 15:24:10 +12:00
include We have a patch that adds an initial set of tracepoints to the MDS 2025-12-14 15:24:10 +12:00
init Significant patch series in this pull request: 2025-12-06 14:01:20 -08:00
io_uring io_uring-6.19-20251211 2025-12-12 22:01:32 +12:00
ipc Significant patch series in this pull request: 2025-12-06 14:01:20 -08:00
kernel Fix CPU hotplug callbacks to disable interrupts on UP kernels. 2025-12-14 06:12:46 +12:00
lib Miscellaneous fixes: 2025-12-14 06:04:16 +12:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm There are no significant series in this small merge. Please see the 2025-12-13 20:55:12 +12:00
net We have a patch that adds an initial set of tracepoints to the MDS 2025-12-14 15:24:10 +12:00
rust rust: poll: add __rust_helper to helpers 2025-12-15 14:13:04 +01:00
samples USB/Thunderbolt changes for 6.19-rc1 2025-12-06 18:42:12 -08:00
scripts There are no significant series in this small merge. Please see the 2025-12-13 20:55:12 +12:00
security Trivial optimization. 2025-12-14 15:21:02 +12:00
sound soundwire updates for 6.19 2025-12-13 16:26:55 +12:00
tools Futex changes for v6.19: 2025-12-10 17:21:30 +09:00
usr initramfs: add gen_init_cpio to hostprogs unconditionally 2025-11-26 21:55:40 +01:00
virt soc: driver updates for 6.19 2025-12-05 17:29:04 -08:00
.clang-format Significant patch series in this merge are as follows: 2025-12-05 13:52:43 -08:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: kbuild: add proc macro library support 2025-11-24 17:15:36 +01:00
.mailmap Significant patch series in this pull request: 2025-12-06 14:01:20 -08:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS phy-for-6.19 2025-12-09 06:31:47 +09:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Patch series in this pull request: 2025-12-13 20:35:41 +12:00
Makefile Linux 6.19-rc1 2025-12-14 16:05:07 +12:00
README README: restructure with role-based documentation and guidelines 2025-11-29 08:40:33 -07:00

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

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer - Getting started with kernel development
* Academic Researcher - Studying kernel internals and architecture
* Security Expert - Hardening and vulnerability analysis
* Backport/Maintenance Engineer - Maintaining stable kernels
* System Administrator - Configuring and troubleshooting
* Maintainer - Leading subsystems and reviewing patches
* Hardware Vendor - Writing drivers for new hardware
* Distribution Maintainer - Packaging kernels for distros


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst



Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst