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Commit cd26ea6d authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo
Browse files

perf trace: Fix setting of augmented payload when using eBPF + raw_syscalls 

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
(sizeof(long)) 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.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-nlslrg8apxdsobt4pwl3n7ur@git.kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 3c5e3dab

tools/perf/builtin-trace.c

+30 −7
Original line number Diff line number Diff line
@@ -108,6 +108,7 @@ struct trace { 
	} stats;

	unsigned int		max_stack;

	unsigned int		min_stack;

	bool			raw_augmented_syscalls;

	bool			not_ev_qualifier;

	bool			live;

	bool			full_time;
@@ -1724,13 +1725,28 @@ static int trace__fprintf_sample(struct trace *trace, struct perf_evsel *evsel, 
	return printed;

}



static void *syscall__augmented_args(struct syscall *sc, struct perf_sample *sample, int *augmented_args_size)

static void *syscall__augmented_args(struct syscall *sc, struct perf_sample *sample, int *augmented_args_size, bool raw_augmented)

{

	void *augmented_args = NULL;

	/*

	 * 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 (sizeof(long)) 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.

	 */

	int args_size = raw_augmented ? (8 * (int)sizeof(long)) : sc->args_size;



	*augmented_args_size = sample->raw_size - sc->args_size;

	*augmented_args_size = sample->raw_size - args_size;

	if (*augmented_args_size > 0)

		augmented_args = sample->raw_data + sc->args_size;

		augmented_args = sample->raw_data + args_size;



	return augmented_args;

}
@@ -1780,7 +1796,7 @@ static int trace__sys_enter(struct trace *trace, struct perf_evsel *evsel, 
	 * here and avoid using augmented syscalls when the evsel is the raw_syscalls one.

	 */

	if (evsel != trace->syscalls.events.sys_enter)

		augmented_args = syscall__augmented_args(sc, sample, &augmented_args_size);

		augmented_args = syscall__augmented_args(sc, sample, &augmented_args_size, trace->raw_augmented_syscalls);

	ttrace->entry_time = sample->time;

	msg = ttrace->entry_str;

	printed += scnprintf(msg + printed, trace__entry_str_size - printed, "%s(", sc->name);
@@ -1833,7 +1849,7 @@ static int trace__fprintf_sys_enter(struct trace *trace, struct perf_evsel *evse 
		goto out_put;



	args = perf_evsel__sc_tp_ptr(evsel, args, sample);

	augmented_args = syscall__augmented_args(sc, sample, &augmented_args_size);

	augmented_args = syscall__augmented_args(sc, sample, &augmented_args_size, trace->raw_augmented_syscalls);

	syscall__scnprintf_args(sc, msg, sizeof(msg), args, augmented_args, augmented_args_size, trace, thread);

	fprintf(trace->output, "%s", msg);

	err = 0;
@@ -3501,8 +3517,15 @@ int cmd_trace(int argc, const char **argv) 
		evsel->handler = trace__sys_enter;



		evlist__for_each_entry(trace.evlist, evsel) {

			if (strstarts(perf_evsel__name(evsel), "syscalls:sys_exit_") ||

			    strcmp(perf_evsel__name(evsel), "raw_syscalls:sys_exit") == 0) {

			bool raw_syscalls_sys_exit = strcmp(perf_evsel__name(evsel), "raw_syscalls:sys_exit") == 0;



			if (raw_syscalls_sys_exit) {

				trace.raw_augmented_syscalls = true;

				goto init_augmented_syscall_tp;

			}



			if (strstarts(perf_evsel__name(evsel), "syscalls:sys_exit_")) {

init_augmented_syscall_tp:

				perf_evsel__init_augmented_syscall_tp(evsel);

				perf_evsel__init_augmented_syscall_tp_ret(evsel);

				evsel->handler = trace__sys_exit;