selftests/bpf: Add tests for ENUMVAL_EXISTS/ENUMVAL_VALUE relocations

Add tests validating existence and value relocations for enum value-based
relocations. If __builtin_preserve_enum_value() built-in is not supported,
skip tests.

Signed-off-by: Andrii Nakryiko <[e-mail]>
Signed-off-by: Alexei Starovoitov <[e-mail]>
Acked-by: Yonghong Song <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

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

···
 	.fails = true,							\
 }
 
+#define ENUMVAL_CASE_COMMON(name)					\
+	.case_name = #name,						\
+	.bpf_obj_file = "test_core_reloc_enumval.o",			\
+	.btf_src_file = "btf__core_reloc_" #name ".o"			\
+
+#define ENUMVAL_CASE(name, ...) {					\
+	ENUMVAL_CASE_COMMON(name),					\
+	.output = STRUCT_TO_CHAR_PTR(core_reloc_enumval_output)		\
+			__VA_ARGS__,					\
+	.output_len = sizeof(struct core_reloc_enumval_output),		\
+}
+
+#define ENUMVAL_ERR_CASE(name) {					\
+	ENUMVAL_CASE_COMMON(name),					\
+	.fails = true,							\
+}
+
 struct core_reloc_test_case;
 
 typedef int (*setup_test_fn)(struct core_reloc_test_case *test);
···
 	/* BTF_TYPE_ID_LOCAL/BTF_TYPE_ID_TARGET tests */
 	TYPE_ID_CASE(type_id, setup_type_id_case_success),
 	TYPE_ID_CASE(type_id___missing_targets, setup_type_id_case_failure),
+
+	/* Enumerator value existence and value relocations */
+	ENUMVAL_CASE(enumval, {
+		.named_val1_exists = true,
+		.named_val2_exists = true,
+		.named_val3_exists = true,
+		.anon_val1_exists = true,
+		.anon_val2_exists = true,
+		.anon_val3_exists = true,
+		.named_val1 = 1,
+		.named_val2 = 2,
+		.anon_val1 = 0x10,
+		.anon_val2 = 0x20,
+	}),
+	ENUMVAL_CASE(enumval___diff, {
+		.named_val1_exists = true,
+		.named_val2_exists = true,
+		.named_val3_exists = true,
+		.anon_val1_exists = true,
+		.anon_val2_exists = true,
+		.anon_val3_exists = true,
+		.named_val1 = 101,
+		.named_val2 = 202,
+		.anon_val1 = 0x11,
+		.anon_val2 = 0x22,
+	}),
+	ENUMVAL_CASE(enumval___val3_missing, {
+		.named_val1_exists = true,
+		.named_val2_exists = true,
+		.named_val3_exists = false,
+		.anon_val1_exists = true,
+		.anon_val2_exists = true,
+		.anon_val3_exists = false,
+		.named_val1 = 111,
+		.named_val2 = 222,
+		.anon_val1 = 0x111,
+		.anon_val2 = 0x222,
+	}),
+	ENUMVAL_ERR_CASE(enumval___err_missing),
 };
 
 struct data {

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

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

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

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

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

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

tools/testing/selftests/bpf/progs/btf__core_reloc_enumval___val3_missing.c

···
+#include "core_reloc_types.h"
+
+void f(struct core_reloc_enumval___val3_missing x) {}

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

···
 struct core_reloc_type_id___missing_targets {
 	/* nothing */
 };
+
+/*
+ * ENUMERATOR VALUE EXISTENCE AND VALUE RELOCATION
+ */
+struct core_reloc_enumval_output {
+	bool named_val1_exists;
+	bool named_val2_exists;
+	bool named_val3_exists;
+	bool anon_val1_exists;
+	bool anon_val2_exists;
+	bool anon_val3_exists;
+
+	int named_val1;
+	int named_val2;
+	int anon_val1;
+	int anon_val2;
+};
+
+enum named_enum {
+	NAMED_ENUM_VAL1 = 1,
+	NAMED_ENUM_VAL2 = 2,
+	NAMED_ENUM_VAL3 = 3,
+};
+
+typedef enum {
+	ANON_ENUM_VAL1 = 0x10,
+	ANON_ENUM_VAL2 = 0x20,
+	ANON_ENUM_VAL3 = 0x30,
+} anon_enum;
+
+struct core_reloc_enumval {
+	enum named_enum f1;
+	anon_enum f2;
+};
+
+/* differing enumerator values */
+enum named_enum___diff {
+	NAMED_ENUM_VAL1___diff = 101,
+	NAMED_ENUM_VAL2___diff = 202,
+	NAMED_ENUM_VAL3___diff = 303,
+};
+
+typedef enum {
+	ANON_ENUM_VAL1___diff = 0x11,
+	ANON_ENUM_VAL2___diff = 0x22,
+	ANON_ENUM_VAL3___diff = 0x33,
+} anon_enum___diff;
+
+struct core_reloc_enumval___diff {
+	enum named_enum___diff f1;
+	anon_enum___diff f2;
+};
+
+/* missing (optional) third enum value */
+enum named_enum___val3_missing {
+	NAMED_ENUM_VAL1___val3_missing = 111,
+	NAMED_ENUM_VAL2___val3_missing = 222,
+};
+
+typedef enum {
+	ANON_ENUM_VAL1___val3_missing = 0x111,
+	ANON_ENUM_VAL2___val3_missing = 0x222,
+} anon_enum___val3_missing;
+
+struct core_reloc_enumval___val3_missing {
+	enum named_enum___val3_missing f1;
+	anon_enum___val3_missing f2;
+};
+
+/* missing (mandatory) second enum value, should fail */
+enum named_enum___err_missing {
+	NAMED_ENUM_VAL1___err_missing = 1,
+	NAMED_ENUM_VAL3___err_missing = 3,
+};
+
+typedef enum {
+	ANON_ENUM_VAL1___err_missing = 0x111,
+	ANON_ENUM_VAL3___err_missing = 0x222,
+} anon_enum___err_missing;
+
+struct core_reloc_enumval___err_missing {
+	enum named_enum___err_missing f1;
+	anon_enum___err_missing f2;
+};

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

···
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2020 Facebook
+
+#include <linux/bpf.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_core_read.h>
+
+char _license[] SEC("license") = "GPL";
+
+struct {
+	char in[256];
+	char out[256];
+	bool skip;
+} data = {};
+
+enum named_enum {
+	NAMED_ENUM_VAL1 = 1,
+	NAMED_ENUM_VAL2 = 2,
+	NAMED_ENUM_VAL3 = 3,
+};
+
+typedef enum {
+	ANON_ENUM_VAL1 = 0x10,
+	ANON_ENUM_VAL2 = 0x20,
+	ANON_ENUM_VAL3 = 0x30,
+} anon_enum;
+
+struct core_reloc_enumval_output {
+	bool named_val1_exists;
+	bool named_val2_exists;
+	bool named_val3_exists;
+	bool anon_val1_exists;
+	bool anon_val2_exists;
+	bool anon_val3_exists;
+
+	int named_val1;
+	int named_val2;
+	int anon_val1;
+	int anon_val2;
+};
+
+SEC("raw_tracepoint/sys_enter")
+int test_core_enumval(void *ctx)
+{
+#if __has_builtin(__builtin_preserve_enum_value)
+	struct core_reloc_enumval_output *out = (void *)&data.out;
+	enum named_enum named = 0;
+	anon_enum anon = 0;
+
+	out->named_val1_exists = bpf_core_enum_value_exists(named, NAMED_ENUM_VAL1);
+	out->named_val2_exists = bpf_core_enum_value_exists(enum named_enum, NAMED_ENUM_VAL2);
+	out->named_val3_exists = bpf_core_enum_value_exists(enum named_enum, NAMED_ENUM_VAL3);
+
+	out->anon_val1_exists = bpf_core_enum_value_exists(anon, ANON_ENUM_VAL1);
+	out->anon_val2_exists = bpf_core_enum_value_exists(anon_enum, ANON_ENUM_VAL2);
+	out->anon_val3_exists = bpf_core_enum_value_exists(anon_enum, ANON_ENUM_VAL3);
+
+	out->named_val1 = bpf_core_enum_value(named, NAMED_ENUM_VAL1);
+	out->named_val2 = bpf_core_enum_value(named, NAMED_ENUM_VAL2);
+	/* NAMED_ENUM_VAL3 value is optional */
+
+	out->anon_val1 = bpf_core_enum_value(anon, ANON_ENUM_VAL1);
+	out->anon_val2 = bpf_core_enum_value(anon, ANON_ENUM_VAL2);
+	/* ANON_ENUM_VAL3 value is optional */
+#else
+	data.skip = true;
+#endif
+
+	return 0;
+}