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Jie Meng c8f0ee969f bpf: Exhaustive test coverage for signed division and modulo
Extend lib/test_bpf.c to provide comprehensive test coverage for BPF
signed division (SDIV) and signed modulo (SMOD) instructions, both
32-bit and 64-bit variants with immediate operands.

Introduce F_ALU32 and F_SIGNED flags to replace the less readable
bool alu32 and s16 off parameters throughout the test helpers. The
BPF instruction 'off' field is derived from flags only at the point
of instruction encoding.

Changes:
- Add enum { F_ALU32 = 1, F_SIGNED = 2 } for readable test flags.
- __bpf_alu_result(): take u32 flags instead of separate signed/alu32
  parameters. Narrows operands internally for ALU32 (unsigned via u32
  cast, signed via s32 cast) before computing the reference result.
- __bpf_emit_alu64_imm(), __bpf_emit_alu32_imm(): pass flags through
  to __bpf_alu_result, derive 'off' for instruction encoding locally.
- __bpf_fill_alu_imm_regs(): take u32 flags, use F_ALU32/F_SIGNED for
  operand setup and single-line __bpf_alu_result() call.
- __bpf_fill_alu_shift(), __bpf_fill_alu_shift_same_reg(): convert
  bool alu32 parameter to u32 flags for consistency.
- New test fill functions: bpf_fill_alu{32,64}_{sdiv,smod}_imm() and
  bpf_fill_alu{32,64}_{sdiv,smod}_imm_regs(), each testing all
  immediate value magnitudes and all register pair combinations.
- All existing unsigned tests updated to use flags (0 or F_ALU32),
  preserving backward compatibility.

8 new test cases added:
  ALU64_SDIV_K, ALU64_SMOD_K (immediate magnitudes + register combos)
  ALU32_SDIV_K, ALU32_SMOD_K (immediate magnitudes + register combos)

Test results:
  test_bpf: Summary: 1061 PASSED, 0 FAILED, [1049/1049 JIT'ed]
  test_bpf: test_tail_calls: Summary: 10 PASSED, 0 FAILED, [10/10 JIT'ed]
  test_bpf: test_skb_segment: Summary: 2 PASSED, 0 FAILED

Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Jie Meng <jmeng@fb.com>
Link: https://lore.kernel.org/r/20260413172311.3918767-1-jmeng@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-04-20 17:57:36 -07:00
arch parisc architecture fixes and updates for kernel v7.1-rc1: 2026-04-18 11:37:36 -07:00
block for-7.1/block-20260411 2026-04-13 15:51:31 -07:00
certs extract-cert: drop unused definition of PKEY_ID_PKCS7 2026-03-24 21:42:37 +00:00
crypto mm.git review status for linus..mm-nonmm-stable 2026-04-16 20:11:56 -07:00
Documentation Documentation/bpf: Update btf doc with updated vlen, kind sizes 2026-04-20 17:52:48 -07:00
drivers parisc architecture fixes and updates for kernel v7.1-rc1: 2026-04-18 11:37:36 -07:00
fs bpf: Refactor dynptr mutability tracking 2026-04-19 15:16:44 +02:00
include bpf: Extend BTF UAPI vlen, kinds to use unused bits 2026-04-20 17:52:48 -07:00
init memblock: updates for 7.0-rc1 2026-04-18 11:29:14 -07:00
io_uring Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
ipc Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
kernel bpf: Extend BTF UAPI vlen, kinds to use unused bits 2026-04-20 17:52:48 -07:00
lib bpf: Exhaustive test coverage for signed division and modulo 2026-04-20 17:57:36 -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 memblock: updates for 7.0-rc1 2026-04-18 11:29:14 -07:00
net bpf-fixes 2026-04-17 15:58:22 -07:00
rust mm.git review status for linus..mm-stable 2026-04-15 12:59:16 -07:00
samples soc: drivers for 7.1 2026-04-16 20:34:34 -07:00
scripts parisc architecture fixes and updates for kernel v7.1-rc1: 2026-04-18 11:37:36 -07:00
security integrity-v7.1 2026-04-17 15:42:01 -07:00
sound rpmsg updates for v7.1 2026-04-17 14:18:55 -07:00
tools selftests/bpf: Fix up __u16 vlen assumptions 2026-04-20 17:52:48 -07:00
usr kbuild: uapi: also test UAPI headers against C++ compilers 2026-03-25 13:24:42 +01:00
virt Arm: 2026-04-17 07:18:03 -07:00
.clang-format Devicetree updates for v7.0: 2026-02-11 18:27:08 -08:00
.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 Askar 2026-04-15 02:15:02 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rust: provide an option to inline C helpers into Rust 2026-03-30 02:03:52 +02:00
.mailmap CXL changes for v7.1 2026-04-17 15:52:58 -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 Major changes: 2026-04-17 16:35:49 -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 Major changes: 2026-04-17 16:35:49 -07:00
Makefile Kbuild/Kconfig updates for 7.1 2026-04-14 09:18:40 -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