selftests/bpf: use canonical ftrace path

The canonical location for the tracefs filesystem is at
/sys/kernel/tracing.

But, from Documentation/trace/ftrace.rst:

  Before 4.1, all ftrace tracing control files were within the debugfs
  file system, which is typically located at /sys/kernel/debug/tracing.
  For backward compatibility, when mounting the debugfs file system,
  the tracefs file system will be automatically mounted at:

  /sys/kernel/debug/tracing

Many tests in the bpf selftest code still refer to this older debugfs
path, so let's update them to avoid confusion.
Signed-off-by: Ross Zwisler <zwisler@google.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20230313205628.1058720-3-zwisler@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/get_cgroup_id_user.c

@@ -86,8 +86,13 @@ int main(int argc, char **argv)
 	pid = getpid();
 	bpf_map_update_elem(pidmap_fd, &key, &pid, 0);
 
-	snprintf(buf, sizeof(buf),
-		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
+	if (access("/sys/kernel/tracing/trace", F_OK) == 0) {
+		snprintf(buf, sizeof(buf),
+			 "/sys/kernel/tracing/events/%s/id", probe_name);
+	} else {
+		snprintf(buf, sizeof(buf),
+			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
+	}
 	efd = open(buf, O_RDONLY, 0);
 	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
 		goto close_prog;

tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c

@@ -338,7 +338,12 @@ static int get_syms(char ***symsp, size_t *cntp, bool kernel)
 	 * Filtering out duplicates by using hashmap__add, which won't
 	 * add existing entry.
 	 */
-	f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
+
+	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
+		f = fopen("/sys/kernel/tracing/available_filter_functions", "r");
+	else
+		f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
+
 	if (!f)
 		return -EINVAL;
 

tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c

@@ -17,8 +17,13 @@ static void test_task_fd_query_tp_core(const char *probe_name,
 	if (CHECK(err, "bpf_prog_test_load", "err %d errno %d\n", err, errno))
 		goto close_prog;
 
-	snprintf(buf, sizeof(buf),
-		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
+	if (access("/sys/kernel/tracing/trace", F_OK) == 0) {
+		snprintf(buf, sizeof(buf),
+			 "/sys/kernel/tracing/events/%s/id", probe_name);
+	} else {
+		snprintf(buf, sizeof(buf),
+			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
+	}
 	efd = open(buf, O_RDONLY, 0);
 	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
 		goto close_prog;

tools/testing/selftests/bpf/prog_tests/tp_attach_query.c

@@ -16,8 +16,13 @@ void serial_test_tp_attach_query(void)
 	for (i = 0; i < num_progs; i++)
 		obj[i] = NULL;
 
-	snprintf(buf, sizeof(buf),
-		 "/sys/kernel/debug/tracing/events/sched/sched_switch/id");
+	if (access("/sys/kernel/tracing/trace", F_OK) == 0) {
+		snprintf(buf, sizeof(buf),
+			 "/sys/kernel/tracing/events/sched/sched_switch/id");
+	} else {
+		snprintf(buf, sizeof(buf),
+			 "/sys/kernel/debug/tracing/events/sched/sched_switch/id");
+	}
 	efd = open(buf, O_RDONLY, 0);
 	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
 		return;

tools/testing/selftests/bpf/prog_tests/trace_printk.c

@@ -5,7 +5,8 @@
 
 #include "trace_printk.lskel.h"
 
-#define TRACEBUF	"/sys/kernel/debug/tracing/trace_pipe"
+#define TRACEFS_PIPE	"/sys/kernel/tracing/trace_pipe"
+#define DEBUGFS_PIPE	"/sys/kernel/debug/tracing/trace_pipe"
 #define SEARCHMSG	"testing,testing"
 
 void serial_test_trace_printk(void)
@@ -34,8 +35,11 @@ void serial_test_trace_printk(void)
 	if (!ASSERT_OK(err, "trace_printk__attach"))
 		goto cleanup;
 
-	fp = fopen(TRACEBUF, "r");
-	if (!ASSERT_OK_PTR(fp, "fopen(TRACEBUF)"))
+	if (access(TRACEFS_PIPE, F_OK) == 0)
+		fp = fopen(TRACEFS_PIPE, "r");
+	else
+		fp = fopen(DEBUGFS_PIPE, "r");
+	if (!ASSERT_OK_PTR(fp, "fopen(TRACE_PIPE)"))
 		goto cleanup;
 
 	/* We do not want to wait forever if this test fails... */

tools/testing/selftests/bpf/prog_tests/trace_vprintk.c

@@ -5,7 +5,8 @@
 
 #include "trace_vprintk.lskel.h"
 
-#define TRACEBUF	"/sys/kernel/debug/tracing/trace_pipe"
+#define TRACEFS_PIPE	"/sys/kernel/tracing/trace_pipe"
+#define DEBUGFS_PIPE	"/sys/kernel/debug/tracing/trace_pipe"
 #define SEARCHMSG	"1,2,3,4,5,6,7,8,9,10"
 
 void serial_test_trace_vprintk(void)
@@ -27,8 +28,11 @@ void serial_test_trace_vprintk(void)
 	if (!ASSERT_OK(err, "trace_vprintk__attach"))
 		goto cleanup;
 
-	fp = fopen(TRACEBUF, "r");
-	if (!ASSERT_OK_PTR(fp, "fopen(TRACEBUF)"))
+	if (access(TRACEFS_PIPE, F_OK) == 0)
+		fp = fopen(TRACEFS_PIPE, "r");
+	else
+		fp = fopen(DEBUGFS_PIPE, "r");
+	if (!ASSERT_OK_PTR(fp, "fopen(TRACE_PIPE)"))
 		goto cleanup;
 
 	/* We do not want to wait forever if this test fails... */

tools/testing/selftests/bpf/progs/test_stacktrace_map.c

@@ -38,7 +38,7 @@ struct {
 	__type(value, stack_trace_t);
 } stack_amap SEC(".maps");
 
-/* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
+/* taken from /sys/kernel/tracing/events/sched/sched_switch/format */
 struct sched_switch_args {
 	unsigned long long pad;
 	char prev_comm[TASK_COMM_LEN];

tools/testing/selftests/bpf/progs/test_tracepoint.c

@@ -4,7 +4,7 @@
 #include <vmlinux.h>
 #include <bpf/bpf_helpers.h>
 
-/* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
+/* taken from /sys/kernel/tracing/events/sched/sched_switch/format */
 struct sched_switch_args {
 	unsigned long long pad;
 	char prev_comm[TASK_COMM_LEN];

tools/testing/selftests/bpf/test_ftrace.sh

 #!/bin/bash
 
-TR=/sys/kernel/debug/tracing/
+if [[ -e /sys/kernel/tracing/trace ]]; then
+    TR=/sys/kernel/tracing/
+else
+    TR=/sys/kernel/debug/tracing/
+fi
+
 clear_trace() { # reset trace output
     echo > $TR/trace
 }

tools/testing/selftests/bpf/test_tunnel.sh

@@ -571,8 +571,13 @@ setup_xfrm_tunnel()
 
 test_xfrm_tunnel()
 {
+	if [[ -e /sys/kernel/tracing/trace ]]; then
+		TRACE=/sys/kernel/tracing/trace
+	else
+		TRACE=/sys/kernel/debug/tracing/trace
+	fi
 	config_device
-	> /sys/kernel/debug/tracing/trace
+	> ${TRACE}
 	setup_xfrm_tunnel
 	mkdir -p ${BPF_PIN_TUNNEL_DIR}
 	bpftool prog loadall ${BPF_FILE} ${BPF_PIN_TUNNEL_DIR}
@@ -581,11 +586,11 @@ test_xfrm_tunnel()
 		${BPF_PIN_TUNNEL_DIR}/xfrm_get_state
 	ip netns exec at_ns0 ping $PING_ARG 10.1.1.200
 	sleep 1
-	grep "reqid 1" /sys/kernel/debug/tracing/trace
+	grep "reqid 1" ${TRACE}
 	check_err $?
-	grep "spi 0x1" /sys/kernel/debug/tracing/trace
+	grep "spi 0x1" ${TRACE}
 	check_err $?
-	grep "remote ip 0xac100164" /sys/kernel/debug/tracing/trace
+	grep "remote ip 0xac100164" ${TRACE}
 	check_err $?
 	cleanup
 

tools/testing/selftests/bpf/trace_helpers.c

@@ -12,7 +12,8 @@
 #include <sys/mman.h>
 #include "trace_helpers.h"
 
-#define DEBUGFS "/sys/kernel/debug/tracing/"
+#define TRACEFS_PIPE	"/sys/kernel/tracing/trace_pipe"
+#define DEBUGFS_PIPE	"/sys/kernel/debug/tracing/trace_pipe"
 
 #define MAX_SYMS 300000
 static struct ksym syms[MAX_SYMS];
@@ -136,7 +137,10 @@ void read_trace_pipe(void)
 {
 	int trace_fd;
 
-	trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
+	if (access(TRACEFS_PIPE, F_OK) == 0)
+		trace_fd = open(TRACEFS_PIPE, O_RDONLY, 0);
+	else
+		trace_fd = open(DEBUGFS_PIPE, O_RDONLY, 0);
 	if (trace_fd < 0)
 		return;