selftests/bpf: Add CO-RE relos and SEC("?...") to linked_funcs selftests

Enhance linked_funcs selftest with two tricky features that might not
obviously work correctly together. We add CO-RE relocations to entry BPF
programs and mark those programs as non-autoloadable with SEC("?...")
annotation. This makes sure that libbpf itself handles .BTF.ext CO-RE
relocation data matching correctly for SEC("?...") programs, as well as
ensures that BPF static linker handles this correctly (this was the case
before, no changes are necessary, but it wasn't explicitly tested).

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220426004511.2691730-6-andrii@kernel.org

diff --git a/tools/testing/selftests/bpf/prog_tests/linked_funcs.c b/tools/testing/selftests/bpf/prog_tests/linked_funcs.c
index e9916f2817ecf6656c07a9c3d2ed50763263b1ad..cad6645469129d8162c38ca12a931ff946b9a38b 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/linked_funcs.c
+++ b/tools/testing/selftests/bpf/prog_tests/linked_funcs.c
@@ -14,6 +14,12 @@ void test_linked_funcs(void)
        if (!ASSERT_OK_PTR(skel, "skel_open"))
                return;
 
+       /* handler1 and handler2 are marked as SEC("?raw_tp/sys_enter") and
+        * are set to not autoload by default
+        */
+       bpf_program__set_autoload(skel->progs.handler1, true);
+       bpf_program__set_autoload(skel->progs.handler2, true);
+
        skel->rodata->my_tid = syscall(SYS_gettid);
        skel->bss->syscall_id = SYS_getpgid;
 

diff --git a/tools/testing/selftests/bpf/progs/linked_funcs1.c b/tools/testing/selftests/bpf/progs/linked_funcs1.c
index 963b393c37e887eff1d66912636b48dc54e4f1d2..b05571bc67d5b6d768bcb7cb4127873133fe4ce2 100644 (file)
--- a/tools/testing/selftests/bpf/progs/linked_funcs1.c
+++ b/tools/testing/selftests/bpf/progs/linked_funcs1.c
@@ -61,12 +61,17 @@ extern int set_output_val2(int x);
 /* here we'll force set_output_ctx2() to be __hidden in the final obj file */
 __hidden extern void set_output_ctx2(__u64 *ctx);
 
-SEC("raw_tp/sys_enter")
+SEC("?raw_tp/sys_enter")
 int BPF_PROG(handler1, struct pt_regs *regs, long id)
 {
+       static volatile int whatever;
+
        if (my_tid != (u32)bpf_get_current_pid_tgid() || id != syscall_id)
                return 0;
 
+       /* make sure we have CO-RE relocations in main program */
+       whatever = bpf_core_type_size(struct task_struct);
+
        set_output_val2(1000);
        set_output_ctx2(ctx); /* ctx definition is hidden in BPF_PROG macro */
 

diff --git a/tools/testing/selftests/bpf/progs/linked_funcs2.c b/tools/testing/selftests/bpf/progs/linked_funcs2.c
index db195872f4eb5d9d555dee214ab51904b9b59675..ee7e3848ee4fe2be14fbb01c4a515fc6e7733a4c 100644 (file)
--- a/tools/testing/selftests/bpf/progs/linked_funcs2.c
+++ b/tools/testing/selftests/bpf/progs/linked_funcs2.c
@@ -61,12 +61,17 @@ extern int set_output_val1(int x);
 /* here we'll force set_output_ctx1() to be __hidden in the final obj file */
 __hidden extern void set_output_ctx1(__u64 *ctx);
 
-SEC("raw_tp/sys_enter")
+SEC("?raw_tp/sys_enter")
 int BPF_PROG(handler2, struct pt_regs *regs, long id)
 {
+       static volatile int whatever;
+
        if (my_tid != (u32)bpf_get_current_pid_tgid() || id != syscall_id)
                return 0;
 
+       /* make sure we have CO-RE relocations in main program */
+       whatever = bpf_core_type_size(struct task_struct);
+
        set_output_val1(2000);
        set_output_ctx1(ctx); /* ctx definition is hidden in BPF_PROG macro */