From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 08AC946AF0A; Thu, 8 Oct 2026 08:50:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791449417; cv=none; b=B3/88Cyug9TGNYL4LJJimz+1jcCyX/S3Aj2jwru2or8EsDIKRvE5MY42COUv2aCbFhi8a5kIeju9nAldjXJxuvuCayNKsSgXBUelKBYWRcqa2tdgS9KyLJGtq6O80OFjvEw3tRRlAM88ZVhhFBeY6gnQpB+gP9SqR7fOLhyiwpI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791449417; c=relaxed/simple; bh=Y81cjMEOGGoKTTzPC6sX5h2TI6CFz1ACqqBTB/kZF9o=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=X8wDuwFC5TYHsTNXyiT5CkLkh/9Tjwfx+HrwixI71Fnn3/g10ro4ep6xwpawdEROCapWq1pLGdDuhJyaheiu4IQP16m5WCeU0bNjhOOMlg5dwjhb3M9eMPzLeGzh50bRvJGSAQLKJkosFniccaVySQVTQ5os11pHYVu+vFklC+4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mGPOeGbs; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mGPOeGbs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 578F21F000FF; Thu, 8 Oct 2026 08:50:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791449413; bh=a4DZfgRtRM1DfMkYwTNcvGcIRfoRHzGzJb+Heok6HXU=; h=From:To:Cc:Subject:Date; b=mGPOeGbsJ/bnNsddkZbUm/ydGEL0szfbmw6AdL97ACeU3sTLPEkyRS7f3RiWIqxvm /MxFgsw0TaQ35kQFj+940bytBDQpSoxbyOKTat4qiT0/eQBbr4eHWHa9vkddp2bWeX HQhtzEcVnOvcy7fqzsjZyMjeFzxMPH8RQtOjecjVVyVqJB7YeufNKpxacbDQMxJXZ9 7CcyLzCmtPk74kfmB7aEUL3I24Wi6SHz7vaq87HV9D8ke74ODRQep0fK6dW22Dhl6P aT2UpAVpul/lC/zwYDnTvRpNAgU5XDuRpt+iLlAD9lOJplrDuOcuarRKjq7y14iEhU ccw+iySavEnrw== From: Sasha Levin To: linux-api@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Sasha Levin , linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kselftest@vger.kernel.org, workflows@vger.kernel.org, tools@kernel.org, x86@kernel.org, Thomas Gleixner , "Paul E . McKenney" , Greg Kroah-Hartman , Jonathan Corbet , Dmitry Vyukov , Randy Dunlap , Cyril Hrubis , Kees Cook , Jake Edge , David Laight , Gabriele Paoloni , Mauro Carvalho Chehab , Christian Brauner , Alexander Viro , Andrew Morton , Masahiro Yamada , Shuah Khan , Arnd Bergmann , Nathan Chancellor , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers Subject: [PATCH v5 00/11] Kernel API Specification Framework Date: Thu, 8 Oct 2026 04:49:40 -0400 Message-ID: <20261008084956.2911790-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This series adds machinery for documenting kernel APIs in a machine-readable form. The kernel promises not to break user space, but the contract of each interface is written down only as prose in man pages and comments, which tools cannot check. Specifications can document parameter types, valid ranges, constraints, and alignment requirements. They capture return value semantics including success conditions and error codes with their meaning. Execution context requirements, capabilities, locking constraints, signal handling behavior, and side effects can all be formally specified. These specifications live alongside the code they document and are both human-readable and machine-parseable. They can be validated at runtime when CONFIG_KAPI_RUNTIME_CHECKS is enabled, exported via debugfs for userspace tools, and extracted from either vmlinux or source code. The intent is for static analyzers, test generators and documentation tools to consume these specifications. This series adds the framework, the extraction tool, and specifications for five syscalls. The implementation includes a core framework with ELF section storage, kerneldoc integration for inline specification, a debugfs interface for runtime querying, ftrace tracepoints that report each spec'd syscall's parameters and return value, and a Rust-based extraction tool (tools/kapi) supporting JSON, RST, and plain text output formats. Example specifications are provided for the four fundamental file syscalls (sys_open, sys_close, sys_read, sys_write) and for sys_madvise. The series also includes a KUnit test suite with 33 tests and a runtime verification selftest with 31 TAP tests. The series is also available in the "spec" branch of: https://git.kernel.org/pub/scm/linux/kernel/git/sashal/kapi.git Changes since v4: - Rebase onto v7.3-rc6: the sys_open spec accepts O_EMPTYPATH, the madvise spec follows the zap_vma_range() rename, and tools/kapi declares Rust 1.85 to match the kernel minimum. - CONFIG_KAPI_RUNTIME_CHECKS builds on 32-bit and on architectures without a syscall wrapper, and depends on X86 || !ARCH_HAS_SYSCALL_WRAPPER since other architectures never reach the hook. __SYSCALL_DEFINEx gains small hooks instead of a duplicated copy, with the prototypes in . - Correct the syscall specs against the implementation (O_CREAT|O_DIRECTORY, O_PATH flag masking, EOVERFLOW and RLIMIT_FSIZE handling, SUID/SGID clearing, close() error sources, lock descriptions, madvise locking). - kdoc_apispec.py: keep paragraph and line structure in long-desc, notes and examples, stop truncating fields at colons or 512 characters, and emit state-transition conditions and exact success values. - debugfs exports the complete spec as JSON without a fixed-size buffer. tools/kapi gives the same result from --vmlinux and --debugfs, and from --source wherever no preprocessor evaluation is needed. - kernel-doc recognises the KAPI sections only in -apispec mode, so its other output is unchanged. Kbuild generates headers only for sources with a contexts: line plus another KAPI section, regenerates them when the generator changes, and no longer reads stdin when a directory has no such sources. - Fix KAPI_CAP_ALTERNATIVE and add KAPI_SIGNAL_MASK_COUNT. Changes since v3: - Fix the build with CONFIG_KAPI_SPEC=y: scripts/Makefile.build now derives the list of instrumented sources from $(real-obj-y)/$(real-obj-m) instead of a recursive find, and the detection regex matches "contexts:" (the token the syscalls actually use). The previous "context-flags:"-only match found no files, so no *.apispec.h was generated and the guarded includes failed to compile. - Force-include the generated *.apispec.h via a per-object -include cflag in scripts/Makefile.build rather than a manual "#include" at the end of each instrumented source; the include blocks are dropped from fs/open.c and fs/read_write.c. - kernel/Makefile: drop the redundant "obj- += api/"; the obj-$(CONFIG_KAPI_SPEC) gate already covers 'make clean'. - kernel/api/Makefile: build kernel_api_spec.o with obj-y now that the subdir gate lives in kernel/Makefile. - kernel/api/Kconfig: drop the tautological "default n" from KAPI_SPEC, KAPI_RUNTIME_CHECKS and KAPI_SPEC_DEBUGFS. - Add an API specification for sys_madvise. - Add ftrace tracepoints on the runtime-check path: kapi_syscall_enter (spec name and named parameter values) and kapi_syscall_exit (return value and spec match). Changes since v2: - Replace statically sized arrays in the spec structs with const char * pointers to reduce memory footprint and remove string truncation. - Simplify the kerneldoc DSL to short tokens (e.g. `type: uint, input`, `contexts: process, softirq`, `constraint-type: range(0, KMAX)`, `side-effect: alloc_memory`) in place of raw KAPI_* enum names. - tools/kapi: commit Cargo.lock for reproducible offline builds, add a Makefile and README, expand the kerneldoc parser to cover the full DSL, and refactor the vmlinux extractor for the const-pointer layout. - tools/lib/python/kdoc/kdoc_apispec.py expanded to match the DSL so scripts/kernel-doc --apispec emits the structure the extractor consumes. References: v4: https://lore.kernel.org/all/20260529233311.1901670-1-sashal@kernel.org/ v3: https://lore.kernel.org/all/20260424165130.2306833-1-sashal@kernel.org/ v2: https://lore.kernel.org/all/20260322121026.869758-1-sashal@kernel.org/ v1: https://lore.kernel.org/all/20260313150928.2637368-1-sashal@kernel.org/ RFC v5: https://lore.kernel.org/lkml/20251218204239.4159453-1-sashal@kernel.org/ RFC v4: https://lore.kernel.org/lkml/20250825181434.3340805-1-sashal@kernel.org/ RFC v3: https://lore.kernel.org/lkml/20250711114248.2288591-1-sashal@kernel.org/ RFC v2: https://lore.kernel.org/lkml/20250624180742.5795-1-sashal@kernel.org/ RFC v1: https://lore.kernel.org/lkml/20250614134858.790460-1-sashal@kernel.org/ Sasha Levin (11): kernel/api: introduce kernel API specification framework kernel/api: enable kerneldoc-based API specifications kernel/api: add debugfs interface for kernel API specifications tools/kapi: add kernel API specification extraction tool kernel/api: add API specification for sys_open kernel/api: add API specification for sys_close kernel/api: add API specification for sys_read kernel/api: add API specification for sys_write kernel/api: add runtime verification selftest kernel/api: add API specification for sys_madvise kernel/api: add syscall enter/exit tracepoints .gitignore | 1 + Documentation/dev-tools/index.rst | 1 + Documentation/dev-tools/kernel-api-spec.rst | 648 ++++ MAINTAINERS | 13 + Makefile | 1 + arch/x86/include/asm/syscall_wrapper.h | 3 +- fs/open.c | 557 +++ fs/read_write.c | 710 ++++ include/asm-generic/vmlinux.lds.h | 14 + include/linux/kapi_syscall.h | 35 + include/linux/kernel_api_spec.h | 1226 ++++++ include/linux/syscalls.h | 42 +- include/trace/events/kapi.h | 74 + init/Kconfig | 2 + kernel/Makefile | 1 + kernel/api/Kconfig | 74 + kernel/api/Makefile | 13 + kernel/api/internal.h | 25 + kernel/api/kapi_debugfs.c | 553 +++ kernel/api/kapi_kunit.c | 720 ++++ kernel/api/kernel_api_spec.c | 1470 ++++++++ mm/madvise.c | 549 +++ scripts/Makefile.build | 26 + tools/docs/kernel-doc | 12 +- tools/kapi/.gitignore | 3 + tools/kapi/Cargo.lock | 679 ++++ tools/kapi/Cargo.toml | 20 + tools/kapi/Makefile | 33 + tools/kapi/README.md | 33 + tools/kapi/src/extractor/debugfs.rs | 1704 +++++++++ tools/kapi/src/extractor/kerneldoc_parser.rs | 3335 +++++++++++++++++ tools/kapi/src/extractor/mod.rs | 442 +++ tools/kapi/src/extractor/source_parser.rs | 531 +++ .../src/extractor/vmlinux/binary_utils.rs | 461 +++ tools/kapi/src/extractor/vmlinux/mod.rs | 1160 ++++++ tools/kapi/src/formatter/json.rs | 659 ++++ tools/kapi/src/formatter/mod.rs | 220 ++ tools/kapi/src/formatter/plain.rs | 679 ++++ tools/kapi/src/formatter/rst.rs | 802 ++++ tools/kapi/src/main.rs | 123 + tools/lib/python/kdoc/kdoc_apispec.py | 1391 +++++++ tools/lib/python/kdoc/kdoc_files.py | 12 +- tools/lib/python/kdoc/kdoc_parser.py | 101 +- tools/testing/selftests/Makefile | 1 + tools/testing/selftests/kapi/.gitignore | 2 + tools/testing/selftests/kapi/Makefile | 7 + tools/testing/selftests/kapi/kapi_test_util.h | 31 + tools/testing/selftests/kapi/test_kapi.c | 1163 ++++++ 48 files changed, 20350 insertions(+), 12 deletions(-) create mode 100644 Documentation/dev-tools/kernel-api-spec.rst create mode 100644 include/linux/kapi_syscall.h create mode 100644 include/linux/kernel_api_spec.h create mode 100644 include/trace/events/kapi.h create mode 100644 kernel/api/Kconfig create mode 100644 kernel/api/Makefile create mode 100644 kernel/api/internal.h create mode 100644 kernel/api/kapi_debugfs.c create mode 100644 kernel/api/kapi_kunit.c create mode 100644 kernel/api/kernel_api_spec.c create mode 100644 tools/kapi/.gitignore create mode 100644 tools/kapi/Cargo.lock create mode 100644 tools/kapi/Cargo.toml create mode 100644 tools/kapi/Makefile create mode 100644 tools/kapi/README.md create mode 100644 tools/kapi/src/extractor/debugfs.rs create mode 100644 tools/kapi/src/extractor/kerneldoc_parser.rs create mode 100644 tools/kapi/src/extractor/mod.rs create mode 100644 tools/kapi/src/extractor/source_parser.rs create mode 100644 tools/kapi/src/extractor/vmlinux/binary_utils.rs create mode 100644 tools/kapi/src/extractor/vmlinux/mod.rs create mode 100644 tools/kapi/src/formatter/json.rs create mode 100644 tools/kapi/src/formatter/mod.rs create mode 100644 tools/kapi/src/formatter/plain.rs create mode 100644 tools/kapi/src/formatter/rst.rs create mode 100644 tools/kapi/src/main.rs create mode 100644 tools/lib/python/kdoc/kdoc_apispec.py create mode 100644 tools/testing/selftests/kapi/.gitignore create mode 100644 tools/testing/selftests/kapi/Makefile create mode 100644 tools/testing/selftests/kapi/kapi_test_util.h create mode 100644 tools/testing/selftests/kapi/test_kapi.c -- 2.53.0