linux-next.git/kernel/api/kernel_api_spec.c, branch master

kernel/api: add syscall enter/exit tracepoints

2026-10-07T22:26:44+00:00

Add two tracepoints to the CONFIG_KAPI_RUNTIME_CHECKS syscall validation path so the framework's behavior can be observed without the noise and loss of pr_warn_ratelimited(): kapi_syscall_enter - the spec name, the raw argument values, and a rendered "name=value" list of the specified parameters (pointer-like values in hex, signed integers and file descriptors in decimal) kapi_syscall_exit - the spec name, the return value, and whether it matched the specification (spec_match) Both fire only for syscalls that have a KAPI specification and live inside the existing CONFIG_KAPI_RUNTIME_CHECKS region, so they exist exactly when the runtime checks do; they compile to no-ops without CONFIG_TRACEPOINTS and stay dormant until enabled. The parameter list is rendered only when the enter tracepoint is enabled. kapi_syscall_exit is also emitted on the parameter-validation rejection path -- where the validator returns -EINVAL and the real handler is skipped -- with spec_match=0, so every kapi_syscall_enter has a matching exit. Assisted-by: LLM Signed-off-by: Sasha Levin

kernel/api: introduce kernel API specification framework

2026-10-07T22:26:44+00:00

Add a framework for formally documenting kernel APIs with inline specifications. This framework provides: - Structured API documentation with parameter specifications, return values, error conditions, and execution context requirements - Runtime validation capabilities for debugging (CONFIG_KAPI_RUNTIME_CHECKS) - Support for both internal kernel APIs and system calls The framework stores specifications in a dedicated ELF section and provides infrastructure for: - Runtime querying of API documentation - Integration with existing SYSCALL_DEFINE macros A KUnit suite (CONFIG_KAPI_KUNIT_TEST) covers registration, lookup, parameter and return value validation, and JSON export. No specifications are added here; subsequent patches add them for individual syscalls. With CONFIG_KAPI_SPEC=n the SYSCALL_DEFINEx() expansion is unchanged. CONFIG_KAPI_RUNTIME_CHECKS is a debug option: a syscall whose arguments violate its specification returns -EINVAL without running. Assisted-by: LLM Signed-off-by: Sasha Levin