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Viktor Malik ea6992784d perf trace: Refactor augmented_raw_syscalls using bpf_for
The loop for processing syscall args in augment_raw_syscalls has a
history of breaking with Clang updates, see e.g. commit 013eb043f3
("perf trace: Fix BPF loading failure (-E2BIG)") from Clang 15 to 16.

Now, a similar thing happened between Clang 21 and 22. While the issue
is mitigated on the main line by a recent verifier update, it remains
broken on the 6.12 and 6.18 stable branches:

    [linux-6.18.y]# sudo perf trace true
    libbpf: prog 'sys_enter': BPF program load failed: -E2BIG
    libbpf: prog 'sys_enter': -- BEGIN PROG LOAD LOG --
    [...]
    BPF program is too large. Processed 1000001 insn
    processed 1000001 insns (limit 1000000) max_states_per_insn 40 total_states 37941 peak_states 232 mark_read 0
    -- END PROG LOAD LOG --
    libbpf: prog 'sys_enter': failed to load: -E2BIG
    libbpf: failed to load object 'augmented_raw_syscalls_bpf'
    libbpf: failed to load BPF skeleton 'augmented_raw_syscalls_bpf': -E2BIG
    Error: failed to get syscall or beauty map fd
    [...]

The reason is that the loop is quite complex and the BPF verifier often
struggles to prove that it terminates.

Fix the issue by replacing the standard for loop with the bpf_for macro,
which uses a numeric BPF iterator. This should prevent future breakages
of this kind since the verifier has a much easier job proving that the
loop terminates.

Small adjustments were necessary for the loop to make it work.  The main
problem is that the verifier sometimes has problems with bpf_for loops
that use a carry-over state, such as the `payload_offset` and `output`
vars here, since the verifier tries to track their values too precisely
and cannot prove loop convergence. To resolve the issue, we (1)
explicitly recompute `payload_offset` in every iteration and (2) use a
trick with adding a global zero to `output` to help the verifier forget
its precise state and use a range instead.

Finally, to keep backwards compatibility with older kernel versions that
don't have bpf_for (i.e. numeric iterators), fall back to standard loop.

Signed-off-by: Viktor Malik <vmalik@redhat.com>
Cc: stable@vger.kernel.org
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Fixes: a68fd6a6cd ("perf trace: Collect augmented data using BPF")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
History 2026-07-16 10:57:40 -07:00
arch LoongArch changes for v7.2 2026-06-26 08:42:49 -07:00
block block: handle REQ_OP_ZONE_APPEND in __bio_integrity_action 2026-06-24 06:53:25 -06:00
certs treewide: fix indentation and whitespace in Kconfig files 2026-05-28 21:24:42 -07:00
crypto mm.git review status for mm-hotfixes-stable..mm-nonmm-stable 2026-06-21 13:20:19 -07:00
Documentation RTC for 7.2 2026-06-27 11:00:18 -07:00
drivers NTB updates include an EPF bug fix to prevent an invalid unmap during 2026-06-28 07:46:12 -07:00
fs fscrypt fixes for 7.2 2026-06-27 09:20:16 -07:00
include NTB updates include an EPF bug fix to prevent an invalid unmap during 2026-06-28 07:46:12 -07:00
init mm.git review status for mm-hotfixes-stable..mm-nonmm-stable 2026-06-21 13:20:19 -07:00
io_uring io_uring-7.2-20260625 2026-06-25 09:53:31 -07:00
ipc kernel-7.2-rc1.misc 2026-06-15 03:05:50 +05:30
kernel Power management fixes for 7.2-rc1 2026-06-26 13:14:18 -07:00
lib Misc fixes: 2026-06-23 16:05:54 -07:00
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 block-7.2-20260625 2026-06-25 09:56:47 -07:00
net bpf-fixes 2026-06-25 14:09:26 -07:00
rust Rust changes for v7.2 (addendum) 2026-06-24 15:11:08 -07:00
samples Char/Misc/IIO/FPGA/GPIB/etc driver updates for 7.2-rc1 2026-06-22 12:20:21 -07:00
scripts Second round of Kbuild changes for 7.2 2026-06-25 09:06:12 -07:00
security * add Georgia Garcia as co-maintainer of apparmor 2026-06-24 12:33:40 -07:00
sound sound fixes for 7.2-rc1 2026-06-27 12:15:23 -07:00
tools perf trace: Refactor augmented_raw_syscalls using bpf_for 2026-07-16 10:57:40 -07:00
usr kbuild: uapi: also test UAPI headers against C++ compilers 2026-03-25 13:24:42 +01:00
virt s390: 2026-06-25 10:21:13 -07:00
.clang-format clang-format: fix formatting of guard() and scoped_guard() statements 2026-05-28 21:24:41 -07:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add myself 2026-04-02 16:48:25 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore SPDX patches for 7.2-rc1 2026-06-22 12:06:22 -07:00
.mailmap Including fixes from netfilter and IPsec. 2026-06-25 12:25:36 -07:00
.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 mm.git review status for mm-hotfixes-stable..mm-nonmm-stable 2026-06-21 13:20:19 -07:00
Kbuild checksyscalls: move instance functionality into generic code 2026-04-05 09:21:32 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Including fixes from netfilter and IPsec. 2026-06-25 12:25:36 -07:00
Makefile Linux 7.2-rc1 2026-06-28 12:01:31 -07:00
README docs: add AI Coding Assistants documentation 2026-01-06 14:55:06 -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
* AI Coding Assistant - LLMs and AI-powered development tools


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

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


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