diff options
Diffstat (limited to 'internal/generate/bpfhandler.go')
| -rw-r--r-- | internal/generate/bpfhandler.go | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/internal/generate/bpfhandler.go b/internal/generate/bpfhandler.go index 3d3db4a..7b8fea0 100644 --- a/internal/generate/bpfhandler.go +++ b/internal/generate/bpfhandler.go @@ -36,7 +36,13 @@ func generateBPFHandler(tp GeneratedTracepoint) string { // between kernel-assigned enter/exit IDs. enterName := enterConstForHandler(f.Name, isEnter) - return renderHandler(f.Name, ctxStruct, eventStruct, comment, eventTypeConst, extra, isEnter, enterName) + // Noreturn syscalls (exit, exit_group) get a special enter hook that skips + // the syscall_enter_state_map write. Their exit handler is suppressed (see + // codegen.go), so nothing would ever clear a recorded enter-state entry; + // recording it would only leak stale per-tid entries in the bounded map. + noreturn := isEnter && isNoreturnSyscall(syscallName(f.Name)) + + return renderHandler(f.Name, ctxStruct, eventStruct, comment, eventTypeConst, extra, isEnter, noreturn, enterName) } // enterConstForHandler returns the C #define constant name for the @@ -51,7 +57,7 @@ func enterConstForHandler(name string, isEnter bool) string { return strings.Replace(upper, "SYS_EXIT_", "SYS_ENTER_", 1) } -func renderHandler(name, ctxStruct, eventStruct, comment, eventTypeConst, extra string, isEnter bool, enterName string) string { +func renderHandler(name, ctxStruct, eventStruct, comment, eventTypeConst, extra string, isEnter, noreturn bool, enterName string) string { var b strings.Builder fmt.Fprintf(&b, "/// %s is a struct %s\n", name, comment) fmt.Fprintf(&b, "SEC(\"tracepoint/syscalls/%s\")\n", name) @@ -60,7 +66,15 @@ func renderHandler(name, ctxStruct, eventStruct, comment, eventTypeConst, extra b.WriteString(" if (filter(&pid, &tid))\n") b.WriteString(" return 0;\n") b.WriteString("\n") - if isEnter { + if isEnter && noreturn { + // Noreturn enter: only the sampling decision, no enter-state write. The + // syscall never returns, so its exit handler is suppressed and nothing + // would ever look up or delete a recorded enter-state entry. Skipping + // the write avoids leaking stale per-tid entries in the bounded + // syscall_enter_state_map; the enter null_event is still emitted below. + fmt.Fprintf(&b, " if (!ior_on_noreturn_syscall_enter(%s))\n", strings.ToUpper(name)) + b.WriteString(" return 0;\n") + } else if isEnter { fmt.Fprintf(&b, " if (!ior_on_syscall_enter(tid, %s))\n", strings.ToUpper(name)) b.WriteString(" return 0;\n") } else { |