Add selftest validating various aspects of statically linking global
variables:
- correct resolution of extern variables across .bss, .data, and .rodata
sections;
- correct handling of weak definitions;
- correct de-duplication of repeating special externs (.kconfig, .ksyms).
Acked-by: Yonghong Song <yhs@xxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
tools/testing/selftests/bpf/Makefile | 3 +-
.../selftests/bpf/prog_tests/linked_vars.c | 43 +++++++++++++++
.../selftests/bpf/progs/linked_vars1.c | 54 ++++++++++++++++++
.../selftests/bpf/progs/linked_vars2.c | 55 +++++++++++++++++++
4 files changed, 154 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/linked_vars.c
create mode 100644 tools/testing/selftests/bpf/progs/linked_vars1.c
create mode 100644 tools/testing/selftests/bpf/progs/linked_vars2.c
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index ab7b129a8408..411e2cf07ba5 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -309,10 +309,11 @@ endef
SKEL_BLACKLIST := btf__% test_pinning_invalid.c test_sk_assign.c
-LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h
+LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h linked_vars.skel.h
test_static_linked.skel.h-deps := test_static_linked1.o test_static_linked2.o
linked_funcs.skel.h-deps := linked_funcs1.o linked_funcs2.o
+linked_vars.skel.h-deps := linked_vars1.o linked_vars2.o
LINKED_BPF_SRCS := $(patsubst %.o,%.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps)))
diff --git a/tools/testing/selftests/bpf/prog_tests/linked_vars.c b/tools/testing/selftests/bpf/prog_tests/linked_vars.c
new file mode 100644
index 000000000000..267166abe4c1
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/linked_vars.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include <test_progs.h>
+#include <sys/syscall.h>
+#include "linked_vars.skel.h"
+
+void test_linked_vars(void)
+{
+ int err;
+ struct linked_vars *skel;
+
+ skel = linked_vars__open();
+ if (!ASSERT_OK_PTR(skel, "skel_open"))
+ return;
+
+ skel->bss->input_bss1 = 1000;
+ skel->bss->input_bss2 = 2000;
+ skel->bss->input_bss_weak = 3000;
+
+ err = linked_vars__load(skel);
+ if (!ASSERT_OK(err, "skel_load"))
+ goto cleanup;
+
+ err = linked_vars__attach(skel);
+ if (!ASSERT_OK(err, "skel_attach"))
+ goto cleanup;
+
+ /* trigger */
+ syscall(SYS_getpgid);
+
+ ASSERT_EQ(skel->bss->output_bss1, 1000 + 2000 + 3000, "output_bss1");
+ ASSERT_EQ(skel->bss->output_bss2, 1000 + 2000 + 3000, "output_bss2");
+ /* 10 comes from "winner" input_data_weak in first obj file */
+ ASSERT_EQ(skel->bss->output_data1, 1 + 2 + 10, "output_bss1");
+ ASSERT_EQ(skel->bss->output_data2, 1 + 2 + 10, "output_bss2");
+ /* 100 comes from "winner" input_rodata_weak in first obj file */
+ ASSERT_EQ(skel->bss->output_rodata1, 11 + 22 + 100, "output_weak1");
+ ASSERT_EQ(skel->bss->output_rodata2, 11 + 22 + 100, "output_weak2");
+
+cleanup:
+ linked_vars__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/linked_vars1.c b/tools/testing/selftests/bpf/progs/linked_vars1.c
new file mode 100644
index 000000000000..ef9e9d0bb0ca
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/linked_vars1.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+extern int LINUX_KERNEL_VERSION __kconfig;
+/* this weak extern will be strict due to the other file's strong extern */
+extern bool CONFIG_BPF_SYSCALL __kconfig __weak;
+extern const void bpf_link_fops __ksym __weak;
+
+int input_bss1;
+int input_data1 = 1;
+const volatile int input_rodata1 = 11;
+
+int input_bss_weak __weak;
+/* these two definitions should win */
+int input_data_weak __weak = 10;
+const volatile int input_rodata_weak __weak = 100;
+
+extern int input_bss2;
+extern int input_data2;
+extern const int input_rodata2;
+
+int output_bss1;
+int output_data1;
+int output_rodata1;
+
+long output_sink1;
+
+static __noinline int get_bss_res(void)
+{
+ /* just make sure all the relocations work against .text as well */
+ return input_bss1 + input_bss2 + input_bss_weak;
+}
+
+SEC("raw_tp/sys_enter")
+int BPF_PROG(handler1)
+{
+ output_bss1 = get_bss_res();
+ output_data1 = input_data1 + input_data2 + input_data_weak;
+ output_rodata1 = input_rodata1 + input_rodata2 + input_rodata_weak;
+
+ /* make sure we actually use above special externs, otherwise compiler
+ * will optimize them out
+ */
+ output_sink1 = LINUX_KERNEL_VERSION
+ + CONFIG_BPF_SYSCALL
+ + (long)&bpf_link_fops;
+ return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/linked_vars2.c b/tools/testing/selftests/bpf/progs/linked_vars2.c
new file mode 100644
index 000000000000..e4f5bd388a3c
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/linked_vars2.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+extern int LINUX_KERNEL_VERSION __kconfig;
+/* when an extern is defined as both strong and weak, resulting symbol will be strong */
+extern bool CONFIG_BPF_SYSCALL __kconfig;
+extern const void __start_BTF __ksym;
+
+int input_bss2;
+int input_data2 = 2;
+const volatile int input_rodata2 = 22;
+
+int input_bss_weak __weak;
+/* these two weak variables should lose */
+int input_data_weak __weak = 20;
+const volatile int input_rodata_weak __weak = 200;
+
+extern int input_bss1;
+extern int input_data1;
+extern const int input_rodata1;
+
+int output_bss2;
+int output_data2;
+int output_rodata2;
+
+int output_sink2;
+
+static __noinline int get_data_res(void)
+{
+ /* just make sure all the relocations work against .text as well */
+ return input_data1 + input_data2 + input_data_weak;
+}
+
+SEC("raw_tp/sys_enter")
+int BPF_PROG(handler2)
+{
+ output_bss2 = input_bss1 + input_bss2 + input_bss_weak;
+ output_data2 = get_data_res();
+ output_rodata2 = input_rodata1 + input_rodata2 + input_rodata_weak;
+
+ /* make sure we actually use above special externs, otherwise compiler
+ * will optimize them out
+ */
+ output_sink2 = LINUX_KERNEL_VERSION
+ + CONFIG_BPF_SYSCALL
+ + (long)&__start_BTF;
+
+ return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";
--
2.30.2
