perf bench breakpoint: Skip run if no breakpoints available

Based on commit 7d54a4ac ("perf test: Skip watchpoint tests if
no watchpoints available"), hardware breakpoints are not available for
power9 platform and because of that 'perf bench breakpoint' run fails on
power9 platform.

Add code to check for the return value of perf_event_open() in the
breakpoint run and skip the 'perf bench breakpoint' run, if hardware
breakpoints are not available.

Result on power9 system before patch changes:

  [command]# perf bench breakpoint thread
  perf_event_open: No such device

Result on power9 system after patch changes:

  [command]# ./perf bench breakpoint thread
  Skipping perf bench breakpoint thread: No hardware support
Reported-by: Disha Goel <disgoel@linux.vnet.ibm.com>
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Acked-by: Naveen N Rao <naveen@kernel.org>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Disha Goel <disgoel@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20230823075103.190565-1-kjain@linux.ibm.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/bench/breakpoint.c

@@ -47,6 +47,7 @@ struct breakpoint {
 static int breakpoint_setup(void *addr)
 {
 	struct perf_event_attr attr = { .size = 0, };
+	int fd;
 
 	attr.type = PERF_TYPE_BREAKPOINT;
 	attr.size = sizeof(attr);
@@ -56,7 +57,12 @@ static int breakpoint_setup(void *addr)
 	attr.bp_addr = (unsigned long)addr;
 	attr.bp_type = HW_BREAKPOINT_RW;
 	attr.bp_len = HW_BREAKPOINT_LEN_1;
-	return syscall(SYS_perf_event_open, &attr, 0, -1, -1, 0);
+	fd = syscall(SYS_perf_event_open, &attr, 0, -1, -1, 0);
+
+	if (fd < 0)
+		fd = -errno;
+
+	return fd;
 }
 
 static void *passive_thread(void *arg)
@@ -122,9 +128,15 @@ int bench_breakpoint_thread(int argc, const char **argv)
 
 	for (i = 0; i < thread_params.nbreakpoints; i++) {
 		breakpoints[i].fd = breakpoint_setup(&breakpoints[i].watched);
-		if (breakpoints[i].fd == -1)
+
+		if (breakpoints[i].fd < 0) {
+			if (breakpoints[i].fd == -ENODEV) {
+				printf("Skipping perf bench breakpoint thread: No hardware support\n");
+				return 0;
+			}
 			exit((perror("perf_event_open"), EXIT_FAILURE));
 		}
+	}
 	gettimeofday(&start, NULL);
 	for (i = 0; i < thread_params.nparallel; i++) {
 		if (pthread_create(&parallel[i], NULL, breakpoint_thread, &repeat))
@@ -196,8 +208,14 @@ int bench_breakpoint_enable(int argc, const char **argv)
 		exit(EXIT_FAILURE);
 	}
 	fd = breakpoint_setup(&watched);
-	if (fd == -1)
+
+	if (fd < 0) {
+		if (fd == -ENODEV) {
+			printf("Skipping perf bench breakpoint enable: No hardware support\n");
+			return 0;
+		}
 		exit((perror("perf_event_open"), EXIT_FAILURE));
+	}
 	nthreads = enable_params.npassive + enable_params.nactive;
 	threads = calloc(nthreads, sizeof(threads[0]));
 	if (!threads)