perf test: Skip watchpoint tests if no watchpoints available

On IBM Power9, perf watchpoint tests fail since no hardware breakpoints
are available. Detect this by checking the error returned by
perf_event_open() and skip the tests in that case.
Reported-by: Disha Goel <disgoel@linux.vnet.ibm.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Ian Rogers <irogers@google.com>
Reviewed-by: Kajol Jain<kjain@linux.ibm.com>
Tested-by: Kajol Jain<kjain@linux.ibm.com>
Link: https://lore.kernel.org/r/20221121102747.208289-1-naveen.n.rao@linux.vnet.ibm.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-perf-users@vger.kernel.org

tools/perf/tests/wp.c

@@ -59,8 +59,10 @@ static int __event(int wp_type, void *wp_addr, unsigned long wp_len)
 	get__perf_event_attr(&attr, wp_type, wp_addr, wp_len);
 	fd = sys_perf_event_open(&attr, 0, -1, -1,
 				 perf_event_open_cloexec_flag());
-	if (fd < 0)
+	if (fd < 0) {
+		fd = -errno;
 		pr_debug("failed opening event %x\n", attr.bp_type);
+	}
 
 	return fd;
 }
@@ -77,7 +79,7 @@ static int test__wp_ro(struct test_suite *test __maybe_unused,
 
 	fd = __event(HW_BREAKPOINT_R, (void *)&data1, sizeof(data1));
 	if (fd < 0)
-		return -1;
+		return fd == -ENODEV ? TEST_SKIP : -1;
 
 	tmp = data1;
 	WP_TEST_ASSERT_VAL(fd, "RO watchpoint", 1);
@@ -101,7 +103,7 @@ static int test__wp_wo(struct test_suite *test __maybe_unused,
 
 	fd = __event(HW_BREAKPOINT_W, (void *)&data1, sizeof(data1));
 	if (fd < 0)
-		return -1;
+		return fd == -ENODEV ? TEST_SKIP : -1;
 
 	tmp = data1;
 	WP_TEST_ASSERT_VAL(fd, "WO watchpoint", 0);
@@ -126,7 +128,7 @@ static int test__wp_rw(struct test_suite *test __maybe_unused,
 	fd = __event(HW_BREAKPOINT_R | HW_BREAKPOINT_W, (void *)&data1,
 		     sizeof(data1));
 	if (fd < 0)
-		return -1;
+		return fd == -ENODEV ? TEST_SKIP : -1;
 
 	tmp = data1;
 	WP_TEST_ASSERT_VAL(fd, "RW watchpoint", 1);
@@ -150,7 +152,7 @@ static int test__wp_modify(struct test_suite *test __maybe_unused, int subtest _
 
 	fd = __event(HW_BREAKPOINT_W, (void *)&data1, sizeof(data1));
 	if (fd < 0)
-		return -1;
+		return fd == -ENODEV ? TEST_SKIP : -1;
 
 	data1 = tmp;
 	WP_TEST_ASSERT_VAL(fd, "Modify watchpoint", 1);