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Title: Add `@perf_event` program type with full attach/detach/count support by SiyuanSun0736 · Pull Request #18 · multikernel/kernelscript · GitHub

Open Graph Title: Add `@perf_event` program type with full attach/detach/count support by SiyuanSun0736 · Pull Request #18 · multikernel/kernelscript

X Title: Add `@perf_event` program type with full attach/detach/count support by SiyuanSun0736 · Pull Request #18 · multikernel/kernelscript

Description: Summary This PR adds first-class support for @perf_event eBPF programs in KernelScript. Users can now attach eBPF logic to hardware and software performance counters (branch misses, CPU cycles, cache misses, etc.) with a clean, safe, single-file workflow — no manual perf_event_open(2) boilerplate required. New language features @perf_event program attribute @perf_event fn on_branch_miss(ctx: *bpf_perf_event_data) -> i32 { return 0 } perf_event_attr struct literal — passed directly to attach(): var attr = perf_event_attr { counter: branch_misses, pid: -1, // all processes cpu: 0, // CPU 0 period: 1000000, wakeup: 1, inherit: false, exclude_kernel: false, exclude_user: false } var prog = load(on_branch_miss) attach(prog, attr) // two-argument perf_event form detach(prog) perf_counter enum — 9 hardware/software counters: cpu_cycles, instructions, cache_references, cache_misses, branch_instructions, branch_misses, page_faults, context_switches, cpu_migrations Compiler & codegen changes Component Change ast.ml PerfEvent program type, perf_event_attr struct, perf_counter enum type_checker.ml Validates @perf_event signature and perf_event_attr field types ir_generator.ml Recognises PerfEvent program type ebpf_c_codegen.ml Emits SEC("perf_event") and bpf_perf_event_data context context/perf_event_codegen.ml New module for perf event context field access codegen userspace_codegen.ml Full perf_event lifecycle codegen (see below) stdlib.ml attach/detach builtin resolution for perf_event form btf_parser.ml perf_event_attr BTF type extraction Generated userspace C functions (emitted when attach(prog, attr) is used): ks_open_perf_event(ks_perf_event_attr) — maps perf_counter enum → PERF_TYPE_*/PERF_COUNT_*, validates pid/cpu rules, calls syscall(SYS_perf_event_open, ...) ks_read_perf_count(int perf_fd) → int64_t — reads raw counter value via read() ks_print_perf_count(int perf_fd, const char *name) — prints [perf] : with PRId64 Attach sequence (compiler-generated, in order): attr.disabled = 1 — open without starting perf_event_open(2) → perf_fd IOC_RESET — zero the counter before BPF attachment bpf_program__attach_perf_event(prog, perf_fd) — link BPF program IOC_ENABLE — start counting Detach sequence: IOC_DISABLE → bpf_link__destroy → close(perf_fd) pid/cpu validation (enforced at runtime): pid cpu Result ≥ 0 ≥ 0 OK — specific process, specific CPU ≥ 0 -1 OK — specific process, any CPU -1 ≥ 0 OK — all processes, specific CPU (system-wide) -1 -1 Error — rejected Tests New file test_perf_event_attach.ml — 6 test cases: Test What it verifies perf_event_codegen_enforces_pid_cpu_rules pid/cpu validation, IOC_ENABLE/DISABLE, success messages perf_event_counting_starts_correctly disabled=1 → IOC_RESET → attach_perf_event → IOC_ENABLE ordering perf_event_period_and_wakeup_defaults safe defaults (1000000/1) substituted when period/wakeup = 0 perf_event_period_and_wakeup_custom runtime conditional expression emitted for custom values perf_read_count_function_generated ks_read_perf_count and ks_print_perf_count generated correctly standard_attach_uses_libbpf_error_checks all attach branches use libbpf_get_error All 6 tests pass. perf_branch_miss.ks compiles successfully end-to-end. Documentation README.md — @perf_event added to program types overview; new Hardware Performance Counter Programs section with full lifecycle example and perf_counter table SPEC.md — new § 3.1.3 Perf Event Programs: syntax, pid/cpu rules, perf_counter enum, generated C helpers table, attach/detach sequences, compiler implementation notes Testing checklist dune build — passes dune build @tests — all OCaml unit tests pass test_all_examples.sh — perf_branch_miss.ks compiles KS→C→binary successfully (remaining failures are pre-existing and unrelated to this PR)

Open Graph Description: Summary This PR adds first-class support for @perf_event eBPF programs in KernelScript. Users can now attach eBPF logic to hardware and software performance counters (branch misses, CPU cycles, cac...

X Description: Summary This PR adds first-class support for @perf_event eBPF programs in KernelScript. Users can now attach eBPF logic to hardware and software performance counters (branch misses, CPU cycles, cac...

Opengraph URL: https://github.com/multikernel/kernelscript/pull/18

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