selftests/bpf: add CO-RE relocs nesting tests

Add a bunch of test validating correct handling of nested
structs/unions.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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

@@ -28,6 +28,29 @@
 	.fails = true,							\
 }
 
+#define NESTING_DATA(struct_name) STRUCT_TO_CHAR_PTR(struct_name) {	\
+	.a = { .a = { .a = 42 } },					\
+	.b = { .b = { .b = 0xc001 } },					\
+}
+
+#define NESTING_CASE_COMMON(name)					\
+	.case_name = #name,						\
+	.bpf_obj_file = "test_core_reloc_nesting.o",			\
+	.btf_src_file = "btf__core_reloc_" #name ".o"
+
+#define NESTING_CASE(name) {						\
+	NESTING_CASE_COMMON(name),					\
+	.input = NESTING_DATA(core_reloc_##name),			\
+	.input_len = sizeof(struct core_reloc_##name),			\
+	.output = NESTING_DATA(core_reloc_nesting),			\
+	.output_len = sizeof(struct core_reloc_nesting)			\
+}
+
+#define NESTING_ERR_CASE(name) {					\
+	NESTING_CASE_COMMON(name),					\
+	.fails = true,							\
+}
+
 struct core_reloc_test_case {
 	const char *case_name;
 	const char *bpf_obj_file;
@@ -57,6 +80,22 @@ static struct core_reloc_test_case test_cases[] = {
 	FLAVORS_CASE(flavors),
 
 	FLAVORS_ERR_CASE(flavors__err_wrong_name),
+
+	/* various struct/enum nesting and resolution scenarios */
+	NESTING_CASE(nesting),
+	NESTING_CASE(nesting___anon_embed),
+	NESTING_CASE(nesting___struct_union_mixup),
+	NESTING_CASE(nesting___extra_nesting),
+	NESTING_CASE(nesting___dup_compat_types),
+
+	NESTING_ERR_CASE(nesting___err_missing_field),
+	NESTING_ERR_CASE(nesting___err_array_field),
+	NESTING_ERR_CASE(nesting___err_missing_container),
+	NESTING_ERR_CASE(nesting___err_nonstruct_container),
+	NESTING_ERR_CASE(nesting___err_array_container),
+	NESTING_ERR_CASE(nesting___err_dup_incompat_types),
+	NESTING_ERR_CASE(nesting___err_partial_match_dups),
+	NESTING_ERR_CASE(nesting___err_too_deep),
 };
 
 struct data {

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

+#include "core_reloc_types.h"
+
+void f(struct core_reloc_nesting x) {}

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

+#include "core_reloc_types.h"
+
+void f(struct core_reloc_nesting___anon_embed x) {}

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

+#include "core_reloc_types.h"
+
+void f1(struct core_reloc_nesting___dup_compat_types x) {}
+void f2(struct core_reloc_nesting___dup_compat_types__2 x) {}
+void f3(struct core_reloc_nesting___dup_compat_types__3 x) {}

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

+#include "core_reloc_types.h"
+
+void f(struct core_reloc_nesting___err_array_container x) {}

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

+#include "core_reloc_types.h"
+
+void f(struct core_reloc_nesting___err_array_field x) {}

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

+#include "core_reloc_types.h"
+
+void f1(struct core_reloc_nesting___err_dup_incompat_types__1 x) {}
+void f2(struct core_reloc_nesting___err_dup_incompat_types__2 x) {}

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

+#include "core_reloc_types.h"
+
+void f(struct core_reloc_nesting___err_missing_container x) {}

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

+#include "core_reloc_types.h"
+
+void f(struct core_reloc_nesting___err_missing_field x) {}

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

+#include "core_reloc_types.h"
+
+void f(struct core_reloc_nesting___err_nonstruct_container x) {}

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

+#include "core_reloc_types.h"
+
+void f1(struct core_reloc_nesting___err_partial_match_dups__a x) {}
+void f2(struct core_reloc_nesting___err_partial_match_dups__b x) {}

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

+#include "core_reloc_types.h"
+
+void f(struct core_reloc_nesting___err_too_deep x) {}

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

+#include "core_reloc_types.h"
+
+void f(struct core_reloc_nesting___extra_nesting x) {}

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

+#include "core_reloc_types.h"
+
+void f(struct core_reloc_nesting___struct_union_mixup x) {}

tools/testing/selftests/bpf/progs/core_reloc_types.h

@@ -13,3 +13,296 @@ struct core_reloc_flavors__err_wrong_name {
 	int b;
 	int c;
 };
+
+/*
+ * NESTING
+ */
+/* original set up, used to record relocations in BPF program */
+struct core_reloc_nesting_substruct {
+	int a;
+};
+
+union core_reloc_nesting_subunion {
+	int b;
+};
+
+struct core_reloc_nesting {
+	union {
+		struct core_reloc_nesting_substruct a;
+	} a;
+	struct {
+		union core_reloc_nesting_subunion b;
+	} b;
+};
+
+/* inlined anonymous struct/union instead of named structs in original */
+struct core_reloc_nesting___anon_embed {
+	int __just_for_padding;
+	union {
+		struct {
+			int a;
+		} a;
+	} a;
+	struct {
+		union {
+			int b;
+		} b;
+	} b;
+};
+
+/* different mix of nested structs/unions than in original */
+struct core_reloc_nesting___struct_union_mixup {
+	int __a;
+	struct {
+		int __a;
+		union {
+			char __a;
+			int a;
+		} a;
+	} a;
+	int __b;
+	union {
+		int __b;
+		union {
+			char __b;
+			int b;
+		} b;
+	} b;
+};
+
+/* extra anon structs/unions, but still valid a.a.a and b.b.b accessors */
+struct core_reloc_nesting___extra_nesting {
+	int __padding;
+	struct {
+		struct {
+			struct {
+				struct {
+					union {
+						int a;
+					} a;
+				};
+			};
+		} a;
+		int __some_more;
+		struct {
+			union {
+				union {
+					union {
+						struct {
+							int b;
+						};
+					} b;
+				};
+			} b;
+		};
+	};
+};
+
+/* three flavors of same struct with different structure but same layout for
+ * a.a.a and b.b.b, thus successfully resolved and relocatable */
+struct core_reloc_nesting___dup_compat_types {
+	char __just_for_padding;
+	/* 3 more bytes of padding */
+	struct {
+		struct {
+			int a; /* offset 4 */
+		} a;
+	} a;
+	long long __more_padding;
+	struct {
+		struct {
+			int b; /* offset 16 */
+		} b;
+	} b;
+};
+
+struct core_reloc_nesting___dup_compat_types__2 {
+	int __aligned_padding;
+	struct {
+		int __trickier_noop[0];
+		struct {
+			char __some_more_noops[0];
+			int a; /* offset 4 */
+		} a;
+	} a;
+	int __more_padding;
+	struct {
+		struct {
+			struct {
+				int __critical_padding;
+				int b; /* offset 16 */
+			} b;
+			int __does_not_matter;
+		};
+	} b;
+	int __more_irrelevant_stuff;
+};
+
+struct core_reloc_nesting___dup_compat_types__3 {
+	char __correct_padding[4];
+	struct {
+		struct {
+			int a; /* offset 4 */
+		} a;
+	} a;
+	/* 8 byte padding due to next struct's alignment */
+	struct {
+		struct {
+			int b;
+		} b;
+	} b __attribute__((aligned(16)));
+};
+
+/* b.b.b field is missing */
+struct core_reloc_nesting___err_missing_field {
+	struct {
+		struct {
+			int a;
+		} a;
+	} a;
+	struct {
+		struct {
+			int x;
+		} b;
+	} b;
+};
+
+/* b.b.b field is an array of integers instead of plain int */
+struct core_reloc_nesting___err_array_field {
+	struct {
+		struct {
+			int a;
+		} a;
+	} a;
+	struct {
+		struct {
+			int b[1];
+		} b;
+	} b;
+};
+
+/* middle b container is missing */
+struct core_reloc_nesting___err_missing_container {
+	struct {
+		struct {
+			int a;
+		} a;
+	} a;
+	struct {
+		int x;
+	} b;
+};
+
+/* middle b container is referenced through pointer instead of being embedded */
+struct core_reloc_nesting___err_nonstruct_container {
+	struct {
+		struct {
+			int a;
+		} a;
+	} a;
+	struct {
+		struct {
+			int b;
+		} *b;
+	} b;
+};
+
+/* middle b container is an array of structs instead of plain struct */
+struct core_reloc_nesting___err_array_container {
+	struct {
+		struct {
+			int a;
+		} a;
+	} a;
+	struct {
+		struct {
+			int b;
+		} b[1];
+	} b;
+};
+
+/* two flavors of same struct with incompatible layout for b.b.b */
+struct core_reloc_nesting___err_dup_incompat_types__1 {
+	struct {
+		struct {
+			int a; /* offset 0 */
+		} a;
+	} a;
+	struct {
+		struct {
+			int b; /* offset 4 */
+		} b;
+	} b;
+};
+
+struct core_reloc_nesting___err_dup_incompat_types__2 {
+	struct {
+		struct {
+			int a; /* offset 0 */
+		} a;
+	} a;
+	int __extra_padding;
+	struct {
+		struct {
+			int b; /* offset 8 (!) */
+		} b;
+	} b;
+};
+
+/* two flavors of same struct having one of a.a.a and b.b.b, but not both */
+struct core_reloc_nesting___err_partial_match_dups__a {
+	struct {
+		struct {
+			int a;
+		} a;
+	} a;
+};
+
+struct core_reloc_nesting___err_partial_match_dups__b {
+	struct {
+		struct {
+			int b;
+		} b;
+	} b;
+};
+
+struct core_reloc_nesting___err_too_deep {
+	struct {
+		struct {
+			int a;
+		} a;
+	} a;
+	/* 65 levels of nestedness for b.b.b */
+	struct {
+		struct {
+			struct { struct { struct { struct { struct {
+			struct { struct { struct { struct { struct {
+			struct { struct { struct { struct { struct {
+			struct { struct { struct { struct { struct {
+			struct { struct { struct { struct { struct {
+			struct { struct { struct { struct { struct {
+			struct { struct { struct { struct { struct {
+			struct { struct { struct { struct { struct {
+			struct { struct { struct { struct { struct {
+			struct { struct { struct { struct { struct {
+			struct { struct { struct { struct { struct {
+			struct { struct { struct { struct { struct {
+				/* this one is one too much */
+				struct {
+					int b;
+				};
+			}; }; }; }; };
+			}; }; }; }; };
+			}; }; }; }; };
+			}; }; }; }; };
+			}; }; }; }; };
+			}; }; }; }; };
+			}; }; }; }; };
+			}; }; }; }; };
+			}; }; }; }; };
+			}; }; }; }; };
+			}; }; }; }; };
+			}; }; }; }; };
+		} b;
+	} b;
+};

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

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+
+#include <linux/bpf.h>
+#include <stdint.h>
+#include "bpf_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+
+static volatile struct data {
+	char in[256];
+	char out[256];
+} data;
+
+struct core_reloc_nesting_substruct {
+	int a;
+};
+
+union core_reloc_nesting_subunion {
+	int b;
+};
+
+/* int a.a.a and b.b.b accesses */
+struct core_reloc_nesting {
+	union {
+		struct core_reloc_nesting_substruct a;
+	} a;
+	struct {
+		union core_reloc_nesting_subunion b;
+	} b;
+};
+
+SEC("raw_tracepoint/sys_enter")
+int test_core_nesting(void *ctx)
+{
+	struct core_reloc_nesting *in = (void *)&data.in;
+	struct core_reloc_nesting *out = (void *)&data.out;
+
+	if (BPF_CORE_READ(&out->a.a.a, &in->a.a.a))
+		return 1;
+	if (BPF_CORE_READ(&out->b.b.b, &in->b.b.b))
+		return 1;
+
+	return 0;
+}
+