1 files changed, 152 insertions, 2 deletions

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index d8565c9a18a2..200fbe33d5de 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -709,7 +709,6 @@ static struct syscall_fmt {
 	  .arg = { [0] = { .scnprintf = SCA_X86_ARCH_PRCTL_CODE, /* code */ },
 		   [1] = { .scnprintf = SCA_PTR, /* arg2 */ }, }, },
 	{ .name	    = "bind",
-	  .bpf_prog_name = { .sys_enter = "!syscalls:sys_enter_connect", },
 	  .arg = { [0] = { .scnprintf = SCA_INT, /* fd */ },
 		   [1] = { .scnprintf = SCA_SOCKADDR, /* umyaddr */ },
 		   [2] = { .scnprintf = SCA_INT, /* addrlen */ }, }, },
@@ -879,7 +878,6 @@ static struct syscall_fmt {
 	  .arg = { [0] = { .scnprintf = SCA_FDAT, /* olddirfd */ },
 		   [2] = { .scnprintf = SCA_FDAT, /* newdirfd */ }, }, },
 	{ .name	    = "renameat2",
-	  .bpf_prog_name = { .sys_enter = "!syscalls:sys_enter_renameat", },
 	  .arg = { [0] = { .scnprintf = SCA_FDAT, /* olddirfd */ },
 		   [2] = { .scnprintf = SCA_FDAT, /* newdirfd */ },
 		   [4] = { .scnprintf = SCA_RENAMEAT2_FLAGS, /* flags */ }, }, },
@@ -2910,6 +2908,94 @@ static int trace__init_syscalls_bpf_map(struct trace *trace)
 	return __trace__init_syscalls_bpf_map(trace, enabled);
 }
 
+static struct bpf_program *trace__find_usable_bpf_prog_entry(struct trace *trace, struct syscall *sc)
+{
+	struct tep_format_field *field, *candidate_field;
+	int id;
+
+	/*
+	 * We're only interested in syscalls that have a pointer:
+	 */
+	for (field = sc->args; field; field = field->next) {
+		if (field->flags & TEP_FIELD_IS_POINTER)
+			goto try_to_find_pair;
+	}
+
+	return NULL;
+
+try_to_find_pair:
+	for (id = 0; id < trace->sctbl->syscalls.nr_entries; ++id) {
+		struct syscall *pair = trace__syscall_info(trace, NULL, id);
+		struct bpf_program *pair_prog;
+		bool is_candidate = false;
+
+		if (pair == NULL || pair == sc ||
+		    pair->bpf_prog.sys_enter == trace->syscalls.unaugmented_prog)
+			continue;
+
+		for (field = sc->args, candidate_field = pair->args;
+		     field && candidate_field; field = field->next, candidate_field = candidate_field->next) {
+			bool is_pointer = field->flags & TEP_FIELD_IS_POINTER,
+			     candidate_is_pointer = candidate_field->flags & TEP_FIELD_IS_POINTER;
+
+			if (is_pointer) {
+			       if (!candidate_is_pointer) {
+					// The candidate just doesn't copies our pointer arg, might copy other pointers we want.
+					continue;
+			       }
+			} else {
+				if (candidate_is_pointer) {
+					// The candidate might copy a pointer we don't have, skip it.
+					goto next_candidate;
+				}
+				continue;
+			}
+
+			if (strcmp(field->type, candidate_field->type))
+				goto next_candidate;
+
+			is_candidate = true;
+		}
+
+		if (!is_candidate)
+			goto next_candidate;
+
+		/*
+		 * Check if the tentative pair syscall augmenter has more pointers, if it has,
+		 * then it may be collecting that and we then can't use it, as it would collect
+		 * more than what is common to the two syscalls.
+		 */
+		if (candidate_field) {
+			for (candidate_field = candidate_field->next; candidate_field; candidate_field = candidate_field->next)
+				if (candidate_field->flags & TEP_FIELD_IS_POINTER)
+					goto next_candidate;
+		}
+
+		pair_prog = pair->bpf_prog.sys_enter;
+		/*
+		 * If the pair isn't enabled, then its bpf_prog.sys_enter will not
+		 * have been searched for, so search it here and if it returns the
+		 * unaugmented one, then ignore it, otherwise we'll reuse that BPF
+		 * program for a filtered syscall on a non-filtered one.
+		 *
+		 * For instance, we have "!syscalls:sys_enter_renameat" and that is
+		 * useful for "renameat2".
+		 */
+		if (pair_prog == NULL) {
+			pair_prog = trace__find_syscall_bpf_prog(trace, pair, pair->fmt ? pair->fmt->bpf_prog_name.sys_enter : NULL, "enter");
+			if (pair_prog == trace->syscalls.unaugmented_prog)
+				goto next_candidate;
+		}
+
+		pr_debug("Reusing \"%s\" BPF sys_enter augmenter for \"%s\"\n", pair->name, sc->name);
+		return pair_prog;
+	next_candidate:
+		continue;
+	}
+
+	return NULL;
+}
+
 static int trace__init_syscalls_bpf_prog_array_maps(struct trace *trace)
 {
 	int map_enter_fd = bpf_map__fd(trace->syscalls.prog_array.sys_enter),
@@ -2935,6 +3021,70 @@ static int trace__init_syscalls_bpf_prog_array_maps(struct trace *trace)
 			break;
 	}
 
+	/*
+	 * Now lets do a second pass looking for enabled syscalls without
+	 * an augmenter that have a signature that is a superset of another
+	 * syscall with an augmenter so that we can auto-reuse it.
+	 *
+	 * I.e. if we have an augmenter for the "open" syscall that has
+	 * this signature:
+	 *
+	 *   int open(const char *pathname, int flags, mode_t mode);
+	 *
+	 * I.e. that will collect just the first string argument, then we
+	 * can reuse it for the 'creat' syscall, that has this signature:
+	 *
+	 *   int creat(const char *pathname, mode_t mode);
+	 *
+	 * and for:
+	 *
+	 *   int stat(const char *pathname, struct stat *statbuf);
+	 *   int lstat(const char *pathname, struct stat *statbuf);
+	 *
+	 * Because the 'open' augmenter will collect the first arg as a string,
+	 * and leave alone all the other args, which already helps with
+	 * beautifying 'stat' and 'lstat''s pathname arg.
+	 *
+	 * Then, in time, when 'stat' gets an augmenter that collects both
+	 * first and second arg (this one on the raw_syscalls:sys_exit prog
+	 * array tail call, then that one will be used.
+	 */
+	for (key = 0; key < trace->sctbl->syscalls.nr_entries; ++key) {
+		struct syscall *sc = trace__syscall_info(trace, NULL, key);
+		struct bpf_program *pair_prog;
+		int prog_fd;
+
+		if (sc == NULL || sc->bpf_prog.sys_enter == NULL)
+			continue;
+
+		/*
+		 * For now we're just reusing the sys_enter prog, and if it
+		 * already has an augmenter, we don't need to find one.
+		 */
+		if (sc->bpf_prog.sys_enter != trace->syscalls.unaugmented_prog)
+			continue;
+
+		/*
+		 * Look at all the other syscalls for one that has a signature
+		 * that is close enough that we can share:
+		 */
+		pair_prog = trace__find_usable_bpf_prog_entry(trace, sc);
+		if (pair_prog == NULL)
+			continue;
+
+		sc->bpf_prog.sys_enter = pair_prog;
+
+		/*
+		 * Update the BPF_MAP_TYPE_PROG_SHARED for raw_syscalls:sys_enter
+		 * with the fd for the program we're reusing:
+		 */
+		prog_fd = bpf_program__fd(sc->bpf_prog.sys_enter);
+		err = bpf_map_update_elem(map_enter_fd, &key, &prog_fd, BPF_ANY);
+		if (err)
+			break;
+	}
+
+
 	return err;
 }
 #else