selftests/bpf: Validate skeleton gen handles skipped fields

Adjust static_linked selftests to test a mix of global and static variables
and their handling of bpftool's skeleton generation code.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210513233643.194711-1-andrii@kernel.org

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

@@ -27,8 +27,8 @@ void test_static_linked(void)
 	/* trigger */
 	usleep(1);
 
-	ASSERT_EQ(skel->bss->var1, 1 * 2 + 2 + 3, "var1");
-	ASSERT_EQ(skel->bss->var2, 4 * 3 + 5 + 6, "var2");
+	ASSERT_EQ(skel->data->var1, 1 * 2 + 2 + 3, "var1");
+	ASSERT_EQ(skel->data->var2, 4 * 3 + 5 + 6, "var2");
 
 cleanup:
 	test_static_linked__destroy(skel);

tools/testing/selftests/bpf/progs/linked_maps1.c

@@ -75,7 +75,7 @@ int BPF_PROG(handler_exit1)
 	val = bpf_map_lookup_elem(&map_weak, &key);
 	if (val)
 		output_weak1 = *val;
-	
+
 	return 0;
 }
 

tools/testing/selftests/bpf/progs/test_static_linked1.c

@@ -7,7 +7,7 @@
 /* 8-byte aligned .data */
 static volatile long static_var1 = 2;
 static volatile int static_var2 = 3;
-int var1 = 0;
+int var1 = -1;
 /* 4-byte aligned .rodata */
 const volatile int rovar1;
 

tools/testing/selftests/bpf/progs/test_static_linked2.c

@@ -7,7 +7,7 @@
 /* 4-byte aligned .data */
 static volatile int static_var1 = 5;
 static volatile int static_var2 = 6;
-int var2 = 0;
+int var2 = -1;
 /* 8-byte aligned .rodata */
 const volatile long rovar2;