Re: [PATCH v6 18/26] perf trace: Remove unused code

[Aaron Tomlin]

On Mon, Sep 28, 2026 at 11:25:57AM -0700, Ian Rogers wrote:
> From: Namhyung Kim <namhyung@xxxxxxxxxx>
> 
> Now syscall init for augmented arguments is simplified.  Let's get rid
> of dead code.
> 
> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/20250814071754.193265-5-namhyung@xxxxxxxxxx
> Assisted-by: Antigravity:gemini-3.1-pro
> Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> ---
>  tools/perf/builtin-trace.c | 110 -------------------------------------
>  1 file changed, 110 deletions(-)
> 
> diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> index 3dd40f3c3cbb..1be355a3ae22 100644
> --- a/tools/perf/builtin-trace.c
> +++ b/tools/perf/builtin-trace.c
> @@ -490,38 +490,6 @@ static int evsel__init_syscall_tp(struct evsel *evsel)
>  	return -ENOMEM;
>  }
>  
> -static int evsel__init_augmented_syscall_tp(struct evsel *evsel, struct evsel *tp)
> -{
> -	struct syscall_tp *sc = evsel__syscall_tp(evsel);
> -
> -	if (sc != NULL) {
> -		struct tep_format_field *syscall_id = evsel__field(tp, "id");
> -		if (syscall_id == NULL)
> -			syscall_id = evsel__field(tp, "__syscall_nr");
> -		if (syscall_id == NULL ||
> -		    __tp_field__init_uint(&sc->id, syscall_id->size, syscall_id->offset, evsel->needs_swap))
> -			return -EINVAL;
> -
> -		return 0;
> -	}
> -
> -	return -ENOMEM;
> -}
> -
> -static int evsel__init_augmented_syscall_tp_args(struct evsel *evsel)
> -{
> -	struct syscall_tp *sc = __evsel__syscall_tp(evsel);
> -
> -	return __tp_field__init_ptr(&sc->args, sc->id.offset + sizeof(u64));
> -}
> -
> -static int evsel__init_augmented_syscall_tp_ret(struct evsel *evsel)
> -{
> -	struct syscall_tp *sc = __evsel__syscall_tp(evsel);
> -
> -	return __tp_field__init_uint(&sc->ret, sizeof(u64), sc->id.offset + sizeof(u64), evsel->needs_swap);
> -}
> -
>  static int evsel__init_raw_syscall_tp(struct evsel *evsel, void *handler)
>  {
>  	if (evsel__syscall_tp(evsel) != NULL) {
> @@ -5914,7 +5882,6 @@ int cmd_trace(int argc, const char **argv)
>  	};
>  	bool __maybe_unused max_stack_user_set = true;
>  	bool mmap_pages_user_set = true;
> -	struct evsel *evsel;
>  	const char * const trace_subcommands[] = { "record", NULL };
>  	int err = -1;
>  	char bf[BUFSIZ];
> @@ -6080,83 +6047,6 @@ int cmd_trace(int argc, const char **argv)
>  		}
>  	}
>  
> -	/*
> -	 * If we are augmenting syscalls, then combine what we put in the
> -	 * __augmented_syscalls__ BPF map with what is in the
> -	 * syscalls:sys_exit_FOO tracepoints, i.e. just like we do without BPF,
> -	 * combining raw_syscalls:sys_enter with raw_syscalls:sys_exit.
> -	 *
> -	 * We'll switch to look at two BPF maps, one for sys_enter and the
> -	 * other for sys_exit when we start augmenting the sys_exit paths with
> -	 * buffers that are being copied from kernel to userspace, think 'read'
> -	 * syscall.
> -	 */
> -	if (trace.syscalls.events.bpf_output) {
> -		evlist__for_each_entry(trace.evlist, evsel) {
> -			bool raw_syscalls_sys_exit = evsel__name_is(evsel, "raw_syscalls:sys_exit");
> -
> -			if (raw_syscalls_sys_exit) {
> -				trace.raw_augmented_syscalls = true;
> -				goto init_augmented_syscall_tp;
> -			}
> -
> -			if (trace.syscalls.events.bpf_output->priv == NULL &&
> -			    strstr(evsel__name(evsel), "syscalls:sys_enter")) {
> -				struct evsel *augmented = trace.syscalls.events.bpf_output;
> -				if (evsel__init_augmented_syscall_tp(augmented, evsel) ||
> -				    evsel__init_augmented_syscall_tp_args(augmented))
> -					goto out;
> -				/*
> -				 * Augmented is __augmented_syscalls__ BPF_OUTPUT event
> -				 * Above we made sure we can get from the payload the tp fields
> -				 * that we get from syscalls:sys_enter tracefs format file.
> -				 */
> -				augmented->handler = trace__sys_enter;
> -				/*
> -				 * Now we do the same for the *syscalls:sys_enter event so that
> -				 * if we handle it directly, i.e. if the BPF prog returns 0 so
> -				 * as not to filter it, then we'll handle it just like we would
> -				 * for the BPF_OUTPUT one:
> -				 */
> -				if (evsel__init_augmented_syscall_tp(evsel, evsel) ||
> -				    evsel__init_augmented_syscall_tp_args(evsel))
> -					goto out;
> -				evsel->handler = trace__sys_enter;
> -			}
> -
> -			if (strstarts(evsel__name(evsel), "syscalls:sys_exit_")) {
> -				struct syscall_tp *sc;
> -init_augmented_syscall_tp:
> -				if (evsel__init_augmented_syscall_tp(evsel, evsel))
> -					goto out;
> -				sc = __evsel__syscall_tp(evsel);
> -				/*
> -				 * For now with BPF raw_augmented we hook into
> -				 * raw_syscalls:sys_enter and there we get all
> -				 * 6 syscall args plus the tracepoint common
> -				 * fields and the syscall_nr (another long).
> -				 * So we check if that is the case and if so
> -				 * don't look after the sc->args_size but
> -				 * always after the full raw_syscalls:sys_enter
> -				 * payload, which is fixed.
> -				 *
> -				 * We'll revisit this later to pass
> -				 * s->args_size to the BPF augmenter (now
> -				 * tools/perf/examples/bpf/augmented_raw_syscalls.c,
> -				 * so that it copies only what we need for each
> -				 * syscall, like what happens when we use
> -				 * syscalls:sys_enter_NAME, so that we reduce
> -				 * the kernel/userspace traffic to just what is
> -				 * needed for each syscall.
> -				 */
> -				if (trace.raw_augmented_syscalls)
> -					trace.raw_augmented_syscalls_args_size = (6 + 1) * sizeof(long) + sc->id.offset;
> -				evsel__init_augmented_syscall_tp_ret(evsel);
> -				evsel->handler = trace__sys_exit;
> -			}
> -		}
> -	}
> -
>  	if ((argc >= 1) && (strcmp(argv[0], "record") == 0)) {
>  		err = trace__record(&trace, argc-1, &argv[1]);
>  		goto out;
> -- 
> 2.56.0.rc1.315.gc6ed9934b7-goog
> 

Reviewed-by: Aaron Tomlin <atomlin@xxxxxxxxxxx>

-- 
Aaron Tomlin