perf test: Add landlock workload

We'll use it to add a regression test for the BTF augmentation of enum
arguments for tracepoints in 'perf trace':

root@x1:~# perf trace -e landlock_add_rule perf test -w landlock
0.000 ( 0.009 ms): perf/747160 landlock_add_rule(ruleset_fd: 11, rule_type: LANDLOCK_RULE_PATH_BENEATH, rule_attr: 0x7ffd8e258594, flags: 45) = -1 EINVAL (Invalid argument)
0.011 ( 0.002 ms): perf/747160 landlock_add_rule(ruleset_fd: 11, rule_type: LANDLOCK_RULE_NET_PORT, rule_attr: 0x7ffd8e2585a0, flags: 45) = -1 EINVAL (Invalid argument)
root@x1:~#

Committer notes:

It was agreed on the discussion (see Link below) to shorten then name of
the workload from 'landlock_add_rule' to 'landlock', and I moved it to a
separate patch.

Also, to address a build failure from Namhyung, I stopped loading
linux/landlock.h and instead added the used defines, enums and types to
make this build in older systems. All we want is to emit the syscall and
intercept it.

Suggested-by: Arnaldo Carvalho de Melo <[e-mail]>
Signed-off-by: Howard Chu <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Link: https://lore.kernel.org/lkml/[e-mail]
Link: https://lore.kernel.org/r/[e-mail]
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/tests/builtin-test.c

···
 	&workload__sqrtloop,
 	&workload__brstack,
 	&workload__datasym,
+	&workload__landlock,
 };
 
 static int num_subtests(const struct test_suite *t)

tools/perf/tests/tests.h

···
 DECLARE_WORKLOAD(sqrtloop);
 DECLARE_WORKLOAD(brstack);
 DECLARE_WORKLOAD(datasym);
+DECLARE_WORKLOAD(landlock);
 
 extern const char *dso_to_test;
 extern const char *test_objdump_path;

tools/perf/tests/workloads/Build

···
 perf-test-y += sqrtloop.o
 perf-test-y += brstack.o
 perf-test-y += datasym.o
+perf-test-y += landlock.o
 
 CFLAGS_sqrtloop.o         = -g -O0 -fno-inline -U_FORTIFY_SOURCE
 CFLAGS_leafloop.o         = -g -O0 -fno-inline -fno-omit-frame-pointer -U_FORTIFY_SOURCE

tools/perf/tests/workloads/landlock.c

···
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/compiler.h>
+#include <linux/types.h>
+#include <unistd.h>
+#include "../tests.h"
+
+/* This workload was initially added to test enum augmentation with BTF in perf
+ * trace because its the only syscall that has an enum argument. Since it is
+ * a recent addition to the Linux kernel (at the time of the introduction of this
+ * 'perf test' workload) we just add the required types and defines here instead
+ * of including linux/landlock, that isn't available in older systems.
+ *
+ * We are not interested in the the result of the syscall, just in intercepting
+ * its arguments.
+ */
+
+#ifndef __NR_landlock_add_rule
+#define __NR_landlock_add_rule 445
+#endif
+
+#ifndef LANDLOCK_ACCESS_FS_READ_FILE
+#define LANDLOCK_ACCESS_FS_READ_FILE	(1ULL << 2)
+
+#define LANDLOCK_RULE_PATH_BENEATH	1
+
+struct landlock_path_beneath_attr {
+        __u64 allowed_access;
+        __s32 parent_fd;
+};
+#endif
+
+#ifndef LANDLOCK_ACCESS_NET_CONNECT_TCP
+#define LANDLOCK_ACCESS_NET_CONNECT_TCP	(1ULL << 1)
+
+#define LANDLOCK_RULE_NET_PORT		2
+
+struct landlock_net_port_attr {
+	__u64 allowed_access;
+	__u64 port;
+};
+#endif
+
+static int landlock(int argc __maybe_unused, const char **argv __maybe_unused)
+{
+	int fd = 11, flags = 45;
+
+	struct landlock_path_beneath_attr path_beneath_attr = {
+		.allowed_access = LANDLOCK_ACCESS_FS_READ_FILE,
+		.parent_fd = 14,
+	};
+
+	struct landlock_net_port_attr net_port_attr = {
+		.port = 19,
+		.allowed_access = LANDLOCK_ACCESS_NET_CONNECT_TCP,
+	};
+
+	syscall(__NR_landlock_add_rule, fd, LANDLOCK_RULE_PATH_BENEATH,
+		&path_beneath_attr, flags);
+
+	syscall(__NR_landlock_add_rule, fd, LANDLOCK_RULE_NET_PORT,
+		&net_port_attr, flags);
+
+	return 0;
+}
+
+DEFINE_WORKLOAD(landlock);