btf: Make test for ld64imm CO-RE relocations

Added a test which makes sure we do not mess up offsets when replacing a ld64imm with poisoned instructions. Signed-off-by: Dylan Reimerink <[email protected]>
cilium · Feb 21, 2024 · b24722c · b24722c
1 parent 59cb715
commit b24722c
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diff --git a/Makefile b/Makefile
@@ -47,6 +47,7 @@ TARGETS := \
 	btf/testdata/relocs \
 	btf/testdata/relocs_read \
 	btf/testdata/relocs_read_tgt \
+	btf/testdata/relocs_enum \
 	cmd/bpf2go/testdata/minimal
 
 .PHONY: all clean container-all container-shell generate

diff --git a/btf/core_reloc_test.go b/btf/core_reloc_test.go
@@ -110,3 +110,30 @@ func TestCORERelocationRead(t *testing.T) {
 		}
 	})
 }
+
+func TestLD64IMMReloc(t *testing.T) {
+	testutils.SkipOnOldKernel(t, "5.4", "vmlinux BTF in sysfs")
+
+	testutils.Files(t, testutils.Glob(t, "testdata/relocs_enum-*.elf"), func(t *testing.T, file string) {
+		fh, err := os.Open(file)
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer fh.Close()
+
+		spec, err := ebpf.LoadCollectionSpecFromReader(fh)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if spec.ByteOrder != internal.NativeEndian {
+			return
+		}
+
+		coll, err := ebpf.NewCollection(spec)
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer coll.Close()
+	})
+}
diff --git a/btf/testdata/relocs_enum-eb.elf b/btf/testdata/relocs_enum-eb.elf
diff --git a/btf/testdata/relocs_enum-el.elf b/btf/testdata/relocs_enum-el.elf
diff --git a/btf/testdata/relocs_enum.c b/btf/testdata/relocs_enum.c
@@ -0,0 +1,16 @@
+#include "bpf_core_read.h"
+
+enum cgroup_subsys_id {
+	cpuset_cgrp_id,
+	cpuset_cgrp_id_lublub,
+	CGROUP_SUBSYS_COUNT,
+};
+
+#define __section(NAME) __attribute__((section(NAME), used))
+
+__section("socket/core_ld64imm") int core_ld64imm() {
+	if (bpf_core_enum_value_exists(enum cgroup_subsys_id, cpuset_cgrp_id_lublub)) {
+		__attribute__((unused)) const volatile int val = bpf_core_enum_value(enum cgroup_subsys_id, cpuset_cgrp_id_lublub);
+	}
+	return 0;
+}