[RFC PATCH v7 2/7] selftests/bpf: Add test cases for btf__permute functionality

Donglin Peng posted 7 patches 1 week, 5 days ago
There is a newer version of this series
[RFC PATCH v7 2/7] selftests/bpf: Add test cases for btf__permute functionality
Posted by Donglin Peng 1 week, 5 days ago
From: Donglin Peng <pengdonglin@xiaomi.com>

This patch introduces test cases for the btf__permute function to ensure
it works correctly with both base BTF and split BTF scenarios.

The test suite includes:
- test_permute_base: Validates permutation on base BTF
- test_permute_split: Tests permutation on split BTF
- test_permute_drop_base: Validates type dropping on base BTF
- test_permute_drop_split: Tests type dropping on split BTF
- test_permute_drop_dedup: Tests type dropping and deduping

Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Song Liu <song@kernel.org>
Cc: Xiaoqin Zhang <zhangxiaoqin@xiaomi.com>
Signed-off-by: Donglin Peng <pengdonglin@xiaomi.com>
---
 .../selftests/bpf/prog_tests/btf_permute.c    | 608 ++++++++++++++++++
 1 file changed, 608 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/btf_permute.c

diff --git a/tools/testing/selftests/bpf/prog_tests/btf_permute.c b/tools/testing/selftests/bpf/prog_tests/btf_permute.c
new file mode 100644
index 000000000000..f67bf89519b3
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/btf_permute.c
@@ -0,0 +1,608 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 Xiaomi */
+
+#include <test_progs.h>
+#include <bpf/btf.h>
+#include "btf_helpers.h"
+
+/* Ensure btf__permute work as expected with base BTF */
+static void test_permute_base(void)
+{
+	struct btf *btf;
+	__u32 permute_ids[6];
+	int start_id = 1;
+	int err;
+
+	btf = btf__new_empty();
+	if (!ASSERT_OK_PTR(btf, "empty_main_btf"))
+		return;
+
+	btf__add_int(btf, "int", 4, BTF_INT_SIGNED);	/* [1] int */
+	btf__add_ptr(btf, 1);				/* [2] ptr to int */
+	btf__add_struct(btf, "s1", 4);			/* [3] struct s1 { */
+	btf__add_field(btf, "m", 1, 0, 0);		/*       int m; */
+							/* } */
+	btf__add_struct(btf, "s2", 4);			/* [4] struct s2 { */
+	btf__add_field(btf, "m", 1, 0, 0);		/*       int m; */
+							/* } */
+	btf__add_func_proto(btf, 1);			/* [5] int (*)(int *p); */
+	btf__add_func_param(btf, "p", 2);
+	btf__add_func(btf, "f", BTF_FUNC_STATIC, 5);	/* [6] int f(int *p); */
+
+	VALIDATE_RAW_BTF(
+		btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] PTR '(anon)' type_id=1",
+		"[3] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0",
+		"[4] STRUCT 's2' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0",
+		"[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
+		"\t'p' type_id=2",
+		"[6] FUNC 'f' type_id=5 linkage=static");
+
+	permute_ids[1 - start_id] = 4; /* [1] -> [4] */
+	permute_ids[2 - start_id] = 3; /* [2] -> [3] */
+	permute_ids[3 - start_id] = 5; /* [3] -> [5] */
+	permute_ids[4 - start_id] = 1; /* [4] -> [1] */
+	permute_ids[5 - start_id] = 6; /* [5] -> [6] */
+	permute_ids[6 - start_id] = 2; /* [6] -> [2] */
+	err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
+	if (!ASSERT_OK(err, "btf__permute_base"))
+		goto done;
+
+	VALIDATE_RAW_BTF(
+		btf,
+		"[1] STRUCT 's2' size=4 vlen=1\n"
+		"\t'm' type_id=4 bits_offset=0",
+		"[2] FUNC 'f' type_id=6 linkage=static",
+		"[3] PTR '(anon)' type_id=4",
+		"[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[5] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=4 bits_offset=0",
+		"[6] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
+		"\t'p' type_id=3");
+
+	/*
+	 * For base BTF, id_map_cnt must equal to the number of types
+	 * include VOID type
+	 */
+	permute_ids[1 - start_id] = 4; /* [1] -> [4] */
+	permute_ids[2 - start_id] = 3; /* [2] -> [3] */
+	permute_ids[3 - start_id] = 5; /* [3] -> [5] */
+	permute_ids[4 - start_id] = 1; /* [4] -> [1] */
+	permute_ids[5 - start_id] = 6; /* [5] -> [6] */
+	permute_ids[6 - start_id] = 2; /* [6] -> [2] */
+	err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids) - 1, NULL);
+	if (!ASSERT_ERR(err, "btf__permute_base"))
+		goto done;
+
+	VALIDATE_RAW_BTF(
+		btf,
+		"[1] STRUCT 's2' size=4 vlen=1\n"
+		"\t'm' type_id=4 bits_offset=0",
+		"[2] FUNC 'f' type_id=6 linkage=static",
+		"[3] PTR '(anon)' type_id=4",
+		"[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[5] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=4 bits_offset=0",
+		"[6] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
+		"\t'p' type_id=3");
+
+	/* Multiple types can not be mapped to the same ID */
+	permute_ids[1 - start_id] = 4;
+	permute_ids[2 - start_id] = 4;
+	permute_ids[3 - start_id] = 5;
+	permute_ids[4 - start_id] = 1;
+	permute_ids[5 - start_id] = 6;
+	permute_ids[6 - start_id] = 2;
+	err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
+	if (!ASSERT_ERR(err, "btf__permute_base"))
+		goto done;
+
+	VALIDATE_RAW_BTF(
+		btf,
+		"[1] STRUCT 's2' size=4 vlen=1\n"
+		"\t'm' type_id=4 bits_offset=0",
+		"[2] FUNC 'f' type_id=6 linkage=static",
+		"[3] PTR '(anon)' type_id=4",
+		"[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[5] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=4 bits_offset=0",
+		"[6] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
+		"\t'p' type_id=3");
+
+	/* Type ID must be valid */
+	permute_ids[1 - start_id] = 4;
+	permute_ids[2 - start_id] = 3;
+	permute_ids[3 - start_id] = 5;
+	permute_ids[4 - start_id] = 1;
+	permute_ids[5 - start_id] = 7;
+	permute_ids[6 - start_id] = 2;
+	err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
+	if (!ASSERT_ERR(err, "btf__permute_base"))
+		goto done;
+
+	VALIDATE_RAW_BTF(
+		btf,
+		"[1] STRUCT 's2' size=4 vlen=1\n"
+		"\t'm' type_id=4 bits_offset=0",
+		"[2] FUNC 'f' type_id=6 linkage=static",
+		"[3] PTR '(anon)' type_id=4",
+		"[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[5] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=4 bits_offset=0",
+		"[6] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
+		"\t'p' type_id=3");
+
+done:
+	btf__free(btf);
+}
+
+/* Ensure btf__permute work as expected with split BTF */
+static void test_permute_split(void)
+{
+	struct btf *split_btf = NULL, *base_btf = NULL;
+	__u32 permute_ids[4];
+	int err;
+	int start_id;
+
+	base_btf = btf__new_empty();
+	if (!ASSERT_OK_PTR(base_btf, "empty_main_btf"))
+		return;
+
+	btf__add_int(base_btf, "int", 4, BTF_INT_SIGNED);	/* [1] int */
+	btf__add_ptr(base_btf, 1);				/* [2] ptr to int */
+	VALIDATE_RAW_BTF(
+		base_btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] PTR '(anon)' type_id=1");
+	split_btf = btf__new_empty_split(base_btf);
+	if (!ASSERT_OK_PTR(split_btf, "empty_split_btf"))
+		goto cleanup;
+	btf__add_struct(split_btf, "s1", 4);			/* [3] struct s1 { */
+	btf__add_field(split_btf, "m", 1, 0, 0);		/*   int m; */
+								/* } */
+	btf__add_struct(split_btf, "s2", 4);			/* [4] struct s2 { */
+	btf__add_field(split_btf, "m", 1, 0, 0);		/*   int m; */
+								/* } */
+	btf__add_func_proto(split_btf, 1);			/* [5] int (*)(int p); */
+	btf__add_func_param(split_btf, "p", 2);
+	btf__add_func(split_btf, "f", BTF_FUNC_STATIC, 5);	/* [6] int f(int *p); */
+
+	VALIDATE_RAW_BTF(
+		split_btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] PTR '(anon)' type_id=1",
+		"[3] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0",
+		"[4] STRUCT 's2' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0",
+		"[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
+		"\t'p' type_id=2",
+		"[6] FUNC 'f' type_id=5 linkage=static");
+
+	start_id = btf__type_cnt(base_btf);
+	permute_ids[3 - start_id] = 6; /* [3] -> [6] */
+	permute_ids[4 - start_id] = 3; /* [4] -> [3] */
+	permute_ids[5 - start_id] = 5; /* [5] -> [5] */
+	permute_ids[6 - start_id] = 4; /* [6] -> [4] */
+	err = btf__permute(split_btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
+	if (!ASSERT_OK(err, "btf__permute_split"))
+		goto cleanup;
+
+	VALIDATE_RAW_BTF(
+		split_btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] PTR '(anon)' type_id=1",
+		"[3] STRUCT 's2' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0",
+		"[4] FUNC 'f' type_id=5 linkage=static",
+		"[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
+		"\t'p' type_id=2",
+		"[6] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0");
+
+	/*
+	 * For split BTF, id_map_cnt must equal to the number of types
+	 * added on top of base BTF
+	 */
+	permute_ids[3 - start_id] = 4;
+	permute_ids[4 - start_id] = 3;
+	permute_ids[5 - start_id] = 5;
+	permute_ids[6 - start_id] = 6;
+	err = btf__permute(split_btf, permute_ids, 3, NULL);
+	if (!ASSERT_ERR(err, "btf__permute_split"))
+		goto cleanup;
+
+	VALIDATE_RAW_BTF(
+		split_btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] PTR '(anon)' type_id=1",
+		"[3] STRUCT 's2' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0",
+		"[4] FUNC 'f' type_id=5 linkage=static",
+		"[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
+		"\t'p' type_id=2",
+		"[6] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0");
+
+	/* Multiple types can not be mapped to the same ID */
+	permute_ids[3 - start_id] = 4;
+	permute_ids[4 - start_id] = 3;
+	permute_ids[5 - start_id] = 3;
+	permute_ids[6 - start_id] = 6;
+	err = btf__permute(split_btf, permute_ids, 4, NULL);
+	if (!ASSERT_ERR(err, "btf__permute_split"))
+		goto cleanup;
+
+	VALIDATE_RAW_BTF(
+		split_btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] PTR '(anon)' type_id=1",
+		"[3] STRUCT 's2' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0",
+		"[4] FUNC 'f' type_id=5 linkage=static",
+		"[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
+		"\t'p' type_id=2",
+		"[6] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0");
+
+	/* Can not map to base ID */
+	permute_ids[3 - start_id] = 4;
+	permute_ids[4 - start_id] = 2;
+	permute_ids[5 - start_id] = 5;
+	permute_ids[6 - start_id] = 6;
+	err = btf__permute(split_btf, permute_ids, 4, NULL);
+	if (!ASSERT_ERR(err, "btf__permute_split"))
+		goto cleanup;
+
+	VALIDATE_RAW_BTF(
+		split_btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] PTR '(anon)' type_id=1",
+		"[3] STRUCT 's2' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0",
+		"[4] FUNC 'f' type_id=5 linkage=static",
+		"[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
+		"\t'p' type_id=2",
+		"[6] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0");
+
+cleanup:
+	btf__free(split_btf);
+	btf__free(base_btf);
+}
+
+/* Verify btf__permute function drops types correctly with base_btf */
+static void test_permute_drop_base(void)
+{
+	struct btf *btf;
+	__u32 permute_ids[6];
+	int start_id = 1;
+	int err;
+
+	btf = btf__new_empty();
+	if (!ASSERT_OK_PTR(btf, "empty_main_btf"))
+		return;
+
+	btf__add_int(btf, "int", 4, BTF_INT_SIGNED);	/* [1] int */
+	btf__add_ptr(btf, 1);				/* [2] ptr to int */
+	btf__add_struct(btf, "s1", 4);			/* [3] struct s1 { */
+	btf__add_field(btf, "m", 1, 0, 0);		/*       int m; */
+							/* } */
+	btf__add_struct(btf, "s2", 4);			/* [4] struct s2 { */
+	btf__add_field(btf, "m", 1, 0, 0);		/*       int m; */
+							/* } */
+	btf__add_func_proto(btf, 1);			/* [5] int (*)(int *p); */
+	btf__add_func_param(btf, "p", 2);
+	btf__add_func(btf, "f", BTF_FUNC_STATIC, 5);	/* [6] int f(int *p); */
+
+	VALIDATE_RAW_BTF(
+		btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] PTR '(anon)' type_id=1",
+		"[3] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0",
+		"[4] STRUCT 's2' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0",
+		"[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
+		"\t'p' type_id=2",
+		"[6] FUNC 'f' type_id=5 linkage=static");
+
+	/* Drop ID 4 */
+	permute_ids[1 - start_id] = 5; /* [1] -> [5] */
+	permute_ids[2 - start_id] = 1; /* [2] -> [1] */
+	permute_ids[3 - start_id] = 2; /* [3] -> [2] */
+	permute_ids[4 - start_id] = 0; /* Drop [4] */
+	permute_ids[5 - start_id] = 3; /* [5] -> [3] */
+	permute_ids[6 - start_id] = 4; /* [6] -> [4] */
+	err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
+	if (!ASSERT_OK(err, "btf__permute_drop_base"))
+		goto done;
+
+	VALIDATE_RAW_BTF(
+		btf,
+		"[1] PTR '(anon)' type_id=5",
+		"[2] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=5 bits_offset=0",
+		"[3] FUNC_PROTO '(anon)' ret_type_id=5 vlen=1\n"
+		"\t'p' type_id=1",
+		"[4] FUNC 'f' type_id=3 linkage=static",
+		"[5] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED");
+
+	/* Continue dropping */
+	permute_ids[1 - start_id] = 1; /* [1] -> [1] */
+	permute_ids[2 - start_id] = 2; /* [2] -> [2] */
+	permute_ids[3 - start_id] = 3; /* [3] -> [3] */
+	permute_ids[4 - start_id] = 0; /* Drop [4] */
+	permute_ids[5 - start_id] = 4; /* [5] -> [4] */
+	err = btf__permute(btf, permute_ids, 5, NULL);
+	if (!ASSERT_OK(err, "btf__permute_drop_base_fail"))
+		goto done;
+
+
+	VALIDATE_RAW_BTF(
+		btf,
+		"[1] PTR '(anon)' type_id=4",
+		"[2] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=4 bits_offset=0",
+		"[3] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
+		"\t'p' type_id=1",
+		"[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED");
+
+	/* Cannot drop the ID referenced by others */
+	permute_ids[1 - start_id] = 2;
+	permute_ids[2 - start_id] = 3;
+	permute_ids[3 - start_id] = 1;
+	permute_ids[4 - start_id] = 0; /* [4] is referenced by others */
+	err = btf__permute(btf, permute_ids, 4, NULL);
+	if (!ASSERT_ERR(err, "btf__permute_drop_base_fail"))
+		goto done;
+
+	VALIDATE_RAW_BTF(
+		btf,
+		"[1] PTR '(anon)' type_id=4",
+		"[2] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=4 bits_offset=0",
+		"[3] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
+		"\t'p' type_id=1",
+		"[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED");
+
+	/* Drop 2 IDs at once */
+	permute_ids[1 - start_id] = 2; /* [1] -> [2] */
+	permute_ids[2 - start_id] = 0; /* Drop [2] */
+	permute_ids[3 - start_id] = 0; /* Drop [3] */
+	permute_ids[4 - start_id] = 1; /* [4] -> [1] */
+	err = btf__permute(btf, permute_ids, 4, NULL);
+	if (!ASSERT_OK(err, "btf__permute_drop_base_fail"))
+		goto done;
+
+	VALIDATE_RAW_BTF(
+		btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] PTR '(anon)' type_id=1");
+
+	/* Drop all IDs */
+	permute_ids[1 - start_id] = 0; /* Drop [1] */
+	permute_ids[2 - start_id] = 0; /* Drop [2] */
+	err = btf__permute(btf, permute_ids, 2, NULL);
+	if (!ASSERT_OK(err, "btf__permute_drop_base_fail"))
+		goto done;
+	if (!ASSERT_EQ(btf__type_cnt(btf), 1, "btf__permute_drop_base all"))
+		goto done;
+
+done:
+	btf__free(btf);
+}
+
+/* Verify btf__permute function drops types correctly with split BTF */
+static void test_permute_drop_split(void)
+{
+	struct btf *split_btf = NULL, *base_btf = NULL;
+	__u32 permute_ids[4];
+	int err;
+	int start_id;
+
+	base_btf = btf__new_empty();
+	if (!ASSERT_OK_PTR(base_btf, "empty_main_btf"))
+		return;
+
+	btf__add_int(base_btf, "int", 4, BTF_INT_SIGNED);	/* [1] int */
+	btf__add_ptr(base_btf, 1);				/* [2] ptr to int */
+	VALIDATE_RAW_BTF(
+		base_btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] PTR '(anon)' type_id=1");
+	split_btf = btf__new_empty_split(base_btf);
+	if (!ASSERT_OK_PTR(split_btf, "empty_split_btf"))
+		goto cleanup;
+	btf__add_struct(split_btf, "s1", 4);			/* [3] struct s1 { */
+	btf__add_field(split_btf, "m", 1, 0, 0);		/*   int m; */
+								/* } */
+	btf__add_struct(split_btf, "s2", 4);			/* [4] struct s2 { */
+	btf__add_field(split_btf, "m", 1, 0, 0);		/*   int m; */
+								/* } */
+	btf__add_func_proto(split_btf, 1);			/* [5] int (*)(int p); */
+	btf__add_func_param(split_btf, "p", 2);
+	btf__add_func(split_btf, "f", BTF_FUNC_STATIC, 5);	/* [6] int f(int *p); */
+
+	VALIDATE_RAW_BTF(
+		split_btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] PTR '(anon)' type_id=1",
+		"[3] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0",
+		"[4] STRUCT 's2' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0",
+		"[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
+		"\t'p' type_id=2",
+		"[6] FUNC 'f' type_id=5 linkage=static");
+
+	start_id = btf__type_cnt(base_btf);
+
+	/* Drop ID 4 */
+	permute_ids[3 - start_id] = 5; /* [3] -> [5] */
+	permute_ids[4 - start_id] = 0; /* Drop [4] */
+	permute_ids[5 - start_id] = 3; /* [5] -> [3] */
+	permute_ids[6 - start_id] = 4; /* [6] -> [4] */
+	err = btf__permute(split_btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
+	if (!ASSERT_OK(err, "btf__permute_drop_split"))
+		goto cleanup;
+
+	VALIDATE_RAW_BTF(
+		split_btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] PTR '(anon)' type_id=1",
+		"[3] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
+		"\t'p' type_id=2",
+		"[4] FUNC 'f' type_id=3 linkage=static",
+		"[5] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0");
+
+	/* Can not drop the type referenced by others */
+	permute_ids[3 - start_id] = 0; /* [3] is referenced by [4] */
+	permute_ids[4 - start_id] = 4;
+	permute_ids[5 - start_id] = 3;
+	err = btf__permute(split_btf, permute_ids, 3, NULL);
+	if (!ASSERT_ERR(err, "btf__permute_drop_split"))
+		goto cleanup;
+
+	VALIDATE_RAW_BTF(
+		split_btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] PTR '(anon)' type_id=1",
+		"[3] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
+		"\t'p' type_id=2",
+		"[4] FUNC 'f' type_id=3 linkage=static",
+		"[5] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0");
+
+	/* Continue dropping */
+	permute_ids[3 - start_id] = 0; /* Drop [3] */
+	permute_ids[4 - start_id] = 0; /* Drop [4] */
+	permute_ids[5 - start_id] = 3; /* [5] -> [3] */
+	err = btf__permute(split_btf, permute_ids, 3, NULL);
+	if (!ASSERT_OK(err, "btf__permute_drop_split"))
+		goto cleanup;
+
+	VALIDATE_RAW_BTF(
+		split_btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] PTR '(anon)' type_id=1",
+		"[3] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0");
+
+	/* Continue dropping */
+	permute_ids[3 - start_id] = 0; /* Drop [3] */
+	err = btf__permute(split_btf, permute_ids, 1, NULL);
+	if (!ASSERT_OK(err, "btf__permute_drop_split"))
+		goto cleanup;
+
+	VALIDATE_RAW_BTF(
+		split_btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] PTR '(anon)' type_id=1");
+
+cleanup:
+	btf__free(split_btf);
+	btf__free(base_btf);
+}
+
+/* Verify btf__permute then btf__dedup work correctly */
+static void test_permute_drop_dedup(void)
+{
+	struct btf *btf, *new_btf = NULL;
+	const struct btf_header *hdr;
+	const void *btf_data;
+	char expect_strs[] = "\0int\0s1\0m\0tag1\0tag2\0tag3";
+	char expect_strs_dedupped[] = "\0int\0s1\0m\0tag1";
+	__u32 permute_ids[5], btf_size;
+	int start_id = 1;
+	int err;
+
+	btf = btf__new_empty();
+	if (!ASSERT_OK_PTR(btf, "empty_main_btf"))
+		return;
+
+	btf__add_int(btf, "int", 4, BTF_INT_SIGNED);	/* [1] int */
+	btf__add_struct(btf, "s1", 4);			/* [2] struct s1 { */
+	btf__add_field(btf, "m", 1, 0, 0);		/*       int m; */
+							/* } */
+	btf__add_decl_tag(btf, "tag1", 2, -1);		/* [3] tag -> s1: tag1 */
+	btf__add_decl_tag(btf, "tag2", 2, 1);		/* [4] tag -> s1/m: tag2 */
+	btf__add_decl_tag(btf, "tag3", 2, 1);		/* [5] tag -> s1/m: tag3 */
+
+	VALIDATE_RAW_BTF(
+		btf,
+		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
+		"[2] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=1 bits_offset=0",
+		"[3] DECL_TAG 'tag1' type_id=2 component_idx=-1",
+		"[4] DECL_TAG 'tag2' type_id=2 component_idx=1",
+		"[5] DECL_TAG 'tag3' type_id=2 component_idx=1");
+
+	btf_data = btf__raw_data(btf, &btf_size);
+	if (!ASSERT_OK_PTR(btf_data, "btf__raw_data"))
+		goto done;
+	hdr = btf_data;
+	if (!ASSERT_EQ(hdr->str_len, ARRAY_SIZE(expect_strs), "expect_strs"))
+		goto done;
+
+	new_btf = btf__new(btf_data, btf_size);
+	if (!ASSERT_OK_PTR(new_btf, "btf__new"))
+		goto done;
+
+	/* Drop 2 IDs result in unreferenced strings */
+	permute_ids[1 - start_id] = 3; /* [1] -> [3] */
+	permute_ids[2 - start_id] = 1; /* [2] -> [1] */
+	permute_ids[3 - start_id] = 2; /* [3] -> [2] */
+	permute_ids[4 - start_id] = 0; /* Drop result in unreferenced "tag2" */
+	permute_ids[5 - start_id] = 0; /* Drop result in unreferenced "tag3" */
+	err = btf__permute(new_btf, permute_ids, 5, NULL);
+	if (!ASSERT_OK(err, "btf__permute"))
+		goto done;
+
+	VALIDATE_RAW_BTF(
+		new_btf,
+		"[1] STRUCT 's1' size=4 vlen=1\n"
+		"\t'm' type_id=3 bits_offset=0",
+		"[2] DECL_TAG 'tag1' type_id=1 component_idx=-1",
+		"[3] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED");
+
+	btf_data = btf__raw_data(new_btf, &btf_size);
+	if (!ASSERT_OK_PTR(btf_data, "btf__raw_data"))
+		goto done;
+	hdr = btf_data;
+	if (!ASSERT_EQ(hdr->str_len, ARRAY_SIZE(expect_strs), "expect_strs"))
+		goto done;
+
+	err = btf__dedup(new_btf, NULL);
+	if (!ASSERT_OK(err, "btf__dedup"))
+		goto done;
+
+	btf_data = btf__raw_data(new_btf, &btf_size);
+	if (!ASSERT_OK_PTR(btf_data, "btf__raw_data"))
+		goto done;
+	hdr = btf_data;
+	if (!ASSERT_EQ(hdr->str_len, ARRAY_SIZE(expect_strs_dedupped), "expect_strs_dedupped"))
+		goto done;
+
+done:
+	btf__free(btf);
+	btf__free(new_btf);
+}
+
+void test_btf_permute(void)
+{
+	if (test__start_subtest("permute_base"))
+		test_permute_base();
+	if (test__start_subtest("permute_split"))
+		test_permute_split();
+	if (test__start_subtest("permute_drop_base"))
+		test_permute_drop_base();
+	if (test__start_subtest("permute_drop_split"))
+		test_permute_drop_split();
+	if (test__start_subtest("permute_drop_dedup"))
+		test_permute_drop_dedup();
+}
-- 
2.34.1
Re: [RFC PATCH v7 2/7] selftests/bpf: Add test cases for btf__permute functionality
Posted by Eduard Zingerman 1 week, 4 days ago
On Wed, 2025-11-19 at 11:15 +0800, Donglin Peng wrote:
> From: Donglin Peng <pengdonglin@xiaomi.com>
> 
> This patch introduces test cases for the btf__permute function to ensure
> it works correctly with both base BTF and split BTF scenarios.
> 
> The test suite includes:
> - test_permute_base: Validates permutation on base BTF
> - test_permute_split: Tests permutation on split BTF
> - test_permute_drop_base: Validates type dropping on base BTF
> - test_permute_drop_split: Tests type dropping on split BTF
> - test_permute_drop_dedup: Tests type dropping and deduping
> 
> Cc: Eduard Zingerman <eddyz87@gmail.com>
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
> Cc: Alan Maguire <alan.maguire@oracle.com>
> Cc: Song Liu <song@kernel.org>
> Cc: Xiaoqin Zhang <zhangxiaoqin@xiaomi.com>
> Signed-off-by: Donglin Peng <pengdonglin@xiaomi.com>
> ---

Do we have an infrastructure for .btf_ext tests?

[...]
Re: [RFC PATCH v7 2/7] selftests/bpf: Add test cases for btf__permute functionality
Posted by Eduard Zingerman 1 week, 4 days ago
On Wed, 2025-11-19 at 11:15 +0800, Donglin Peng wrote:

[...]

> diff --git a/tools/testing/selftests/bpf/prog_tests/btf_permute.c b/tools/testing/selftests/bpf/prog_tests/btf_permute.c
> new file mode 100644
> index 000000000000..f67bf89519b3
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/btf_permute.c
> @@ -0,0 +1,608 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2025 Xiaomi */
> +
> +#include <test_progs.h>
> +#include <bpf/btf.h>
> +#include "btf_helpers.h"
> +
> +/* Ensure btf__permute work as expected with base BTF */
> +static void test_permute_base(void)
> +{
> +	struct btf *btf;
> +	__u32 permute_ids[6];
> +	int start_id = 1;
> +	int err;
> +
> +	btf = btf__new_empty();
> +	if (!ASSERT_OK_PTR(btf, "empty_main_btf"))
> +		return;
> +
> +	btf__add_int(btf, "int", 4, BTF_INT_SIGNED);	/* [1] int */
> +	btf__add_ptr(btf, 1);				/* [2] ptr to int */
> +	btf__add_struct(btf, "s1", 4);			/* [3] struct s1 { */
> +	btf__add_field(btf, "m", 1, 0, 0);		/*       int m; */
> +							/* } */
> +	btf__add_struct(btf, "s2", 4);			/* [4] struct s2 { */
> +	btf__add_field(btf, "m", 1, 0, 0);		/*       int m; */
> +							/* } */
> +	btf__add_func_proto(btf, 1);			/* [5] int (*)(int *p); */
> +	btf__add_func_param(btf, "p", 2);
> +	btf__add_func(btf, "f", BTF_FUNC_STATIC, 5);	/* [6] int f(int *p); */
> +
> +	VALIDATE_RAW_BTF(
> +		btf,
> +		"[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +		"[2] PTR '(anon)' type_id=1",
> +		"[3] STRUCT 's1' size=4 vlen=1\n"
> +		"\t'm' type_id=1 bits_offset=0",
> +		"[4] STRUCT 's2' size=4 vlen=1\n"
> +		"\t'm' type_id=1 bits_offset=0",
> +		"[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
> +		"\t'p' type_id=2",
> +		"[6] FUNC 'f' type_id=5 linkage=static");
> +
> +	permute_ids[1 - start_id] = 4; /* [1] -> [4] */
> +	permute_ids[2 - start_id] = 3; /* [2] -> [3] */
> +	permute_ids[3 - start_id] = 5; /* [3] -> [5] */
> +	permute_ids[4 - start_id] = 1; /* [4] -> [1] */
> +	permute_ids[5 - start_id] = 6; /* [5] -> [6] */
> +	permute_ids[6 - start_id] = 2; /* [6] -> [2] */
> +	err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
> +	if (!ASSERT_OK(err, "btf__permute_base"))
> +		goto done;
> +
> +	VALIDATE_RAW_BTF(
> +		btf,
> +		"[1] STRUCT 's2' size=4 vlen=1\n"
> +		"\t'm' type_id=4 bits_offset=0",
> +		"[2] FUNC 'f' type_id=6 linkage=static",
> +		"[3] PTR '(anon)' type_id=4",
> +		"[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +		"[5] STRUCT 's1' size=4 vlen=1\n"
> +		"\t'm' type_id=4 bits_offset=0",
> +		"[6] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
> +		"\t'p' type_id=3");
> +
> +	/*
> +	 * For base BTF, id_map_cnt must equal to the number of types
> +	 * include VOID type
> +	 */
> +	permute_ids[1 - start_id] = 4; /* [1] -> [4] */
> +	permute_ids[2 - start_id] = 3; /* [2] -> [3] */
> +	permute_ids[3 - start_id] = 5; /* [3] -> [5] */
> +	permute_ids[4 - start_id] = 1; /* [4] -> [1] */
> +	permute_ids[5 - start_id] = 6; /* [5] -> [6] */
> +	permute_ids[6 - start_id] = 2; /* [6] -> [2] */
> +	err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids) - 1, NULL);
> +	if (!ASSERT_ERR(err, "btf__permute_base"))
> +		goto done;
> +
> +	VALIDATE_RAW_BTF(
> +		btf,
> +		"[1] STRUCT 's2' size=4 vlen=1\n"
> +		"\t'm' type_id=4 bits_offset=0",
> +		"[2] FUNC 'f' type_id=6 linkage=static",
> +		"[3] PTR '(anon)' type_id=4",
> +		"[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +		"[5] STRUCT 's1' size=4 vlen=1\n"
> +		"\t'm' type_id=4 bits_offset=0",
> +		"[6] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
> +		"\t'p' type_id=3");
> +
> +	/* Multiple types can not be mapped to the same ID */
> +	permute_ids[1 - start_id] = 4;
> +	permute_ids[2 - start_id] = 4;
> +	permute_ids[3 - start_id] = 5;
> +	permute_ids[4 - start_id] = 1;
> +	permute_ids[5 - start_id] = 6;
> +	permute_ids[6 - start_id] = 2;
> +	err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
> +	if (!ASSERT_ERR(err, "btf__permute_base"))
> +		goto done;

Nit: Maybe extract the VALIDATE_RAW_BTF as a function, so that it is
     not repeated? Otherwise it is a bit harder to tell that you are
     checking for BTF to be intact if error is returned.
     Same for the test_permute_split() case.

> +
> +	VALIDATE_RAW_BTF(
> +		btf,
> +		"[1] STRUCT 's2' size=4 vlen=1\n"
> +		"\t'm' type_id=4 bits_offset=0",
> +		"[2] FUNC 'f' type_id=6 linkage=static",
> +		"[3] PTR '(anon)' type_id=4",
> +		"[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +		"[5] STRUCT 's1' size=4 vlen=1\n"
> +		"\t'm' type_id=4 bits_offset=0",
> +		"[6] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
> +		"\t'p' type_id=3");

[...]
Re: [RFC PATCH v7 2/7] selftests/bpf: Add test cases for btf__permute functionality
Posted by Donglin Peng 1 week, 3 days ago
On Fri, Nov 21, 2025 at 7:39 AM Eduard Zingerman <eddyz87@gmail.com> wrote:
>
> On Wed, 2025-11-19 at 11:15 +0800, Donglin Peng wrote:
>
> [...]
>
> > diff --git a/tools/testing/selftests/bpf/prog_tests/btf_permute.c b/tools/testing/selftests/bpf/prog_tests/btf_permute.c
> > new file mode 100644
> > index 000000000000..f67bf89519b3
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/btf_permute.c
> > @@ -0,0 +1,608 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2025 Xiaomi */
> > +
> > +#include <test_progs.h>
> > +#include <bpf/btf.h>
> > +#include "btf_helpers.h"
> > +
> > +/* Ensure btf__permute work as expected with base BTF */
> > +static void test_permute_base(void)
> > +{
> > +     struct btf *btf;
> > +     __u32 permute_ids[6];
> > +     int start_id = 1;
> > +     int err;
> > +
> > +     btf = btf__new_empty();
> > +     if (!ASSERT_OK_PTR(btf, "empty_main_btf"))
> > +             return;
> > +
> > +     btf__add_int(btf, "int", 4, BTF_INT_SIGNED);    /* [1] int */
> > +     btf__add_ptr(btf, 1);                           /* [2] ptr to int */
> > +     btf__add_struct(btf, "s1", 4);                  /* [3] struct s1 { */
> > +     btf__add_field(btf, "m", 1, 0, 0);              /*       int m; */
> > +                                                     /* } */
> > +     btf__add_struct(btf, "s2", 4);                  /* [4] struct s2 { */
> > +     btf__add_field(btf, "m", 1, 0, 0);              /*       int m; */
> > +                                                     /* } */
> > +     btf__add_func_proto(btf, 1);                    /* [5] int (*)(int *p); */
> > +     btf__add_func_param(btf, "p", 2);
> > +     btf__add_func(btf, "f", BTF_FUNC_STATIC, 5);    /* [6] int f(int *p); */
> > +
> > +     VALIDATE_RAW_BTF(
> > +             btf,
> > +             "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> > +             "[2] PTR '(anon)' type_id=1",
> > +             "[3] STRUCT 's1' size=4 vlen=1\n"
> > +             "\t'm' type_id=1 bits_offset=0",
> > +             "[4] STRUCT 's2' size=4 vlen=1\n"
> > +             "\t'm' type_id=1 bits_offset=0",
> > +             "[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
> > +             "\t'p' type_id=2",
> > +             "[6] FUNC 'f' type_id=5 linkage=static");
> > +
> > +     permute_ids[1 - start_id] = 4; /* [1] -> [4] */
> > +     permute_ids[2 - start_id] = 3; /* [2] -> [3] */
> > +     permute_ids[3 - start_id] = 5; /* [3] -> [5] */
> > +     permute_ids[4 - start_id] = 1; /* [4] -> [1] */
> > +     permute_ids[5 - start_id] = 6; /* [5] -> [6] */
> > +     permute_ids[6 - start_id] = 2; /* [6] -> [2] */
> > +     err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
> > +     if (!ASSERT_OK(err, "btf__permute_base"))
> > +             goto done;
> > +
> > +     VALIDATE_RAW_BTF(
> > +             btf,
> > +             "[1] STRUCT 's2' size=4 vlen=1\n"
> > +             "\t'm' type_id=4 bits_offset=0",
> > +             "[2] FUNC 'f' type_id=6 linkage=static",
> > +             "[3] PTR '(anon)' type_id=4",
> > +             "[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> > +             "[5] STRUCT 's1' size=4 vlen=1\n"
> > +             "\t'm' type_id=4 bits_offset=0",
> > +             "[6] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
> > +             "\t'p' type_id=3");
> > +
> > +     /*
> > +      * For base BTF, id_map_cnt must equal to the number of types
> > +      * include VOID type
> > +      */
> > +     permute_ids[1 - start_id] = 4; /* [1] -> [4] */
> > +     permute_ids[2 - start_id] = 3; /* [2] -> [3] */
> > +     permute_ids[3 - start_id] = 5; /* [3] -> [5] */
> > +     permute_ids[4 - start_id] = 1; /* [4] -> [1] */
> > +     permute_ids[5 - start_id] = 6; /* [5] -> [6] */
> > +     permute_ids[6 - start_id] = 2; /* [6] -> [2] */
> > +     err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids) - 1, NULL);
> > +     if (!ASSERT_ERR(err, "btf__permute_base"))
> > +             goto done;
> > +
> > +     VALIDATE_RAW_BTF(
> > +             btf,
> > +             "[1] STRUCT 's2' size=4 vlen=1\n"
> > +             "\t'm' type_id=4 bits_offset=0",
> > +             "[2] FUNC 'f' type_id=6 linkage=static",
> > +             "[3] PTR '(anon)' type_id=4",
> > +             "[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> > +             "[5] STRUCT 's1' size=4 vlen=1\n"
> > +             "\t'm' type_id=4 bits_offset=0",
> > +             "[6] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
> > +             "\t'p' type_id=3");
> > +
> > +     /* Multiple types can not be mapped to the same ID */
> > +     permute_ids[1 - start_id] = 4;
> > +     permute_ids[2 - start_id] = 4;
> > +     permute_ids[3 - start_id] = 5;
> > +     permute_ids[4 - start_id] = 1;
> > +     permute_ids[5 - start_id] = 6;
> > +     permute_ids[6 - start_id] = 2;
> > +     err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
> > +     if (!ASSERT_ERR(err, "btf__permute_base"))
> > +             goto done;
>
> Nit: Maybe extract the VALIDATE_RAW_BTF as a function, so that it is
>      not repeated? Otherwise it is a bit harder to tell that you are
>      checking for BTF to be intact if error is returned.
>      Same for the test_permute_split() case.

Thanks, I will make it more clear.

>
> > +
> > +     VALIDATE_RAW_BTF(
> > +             btf,
> > +             "[1] STRUCT 's2' size=4 vlen=1\n"
> > +             "\t'm' type_id=4 bits_offset=0",
> > +             "[2] FUNC 'f' type_id=6 linkage=static",
> > +             "[3] PTR '(anon)' type_id=4",
> > +             "[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> > +             "[5] STRUCT 's1' size=4 vlen=1\n"
> > +             "\t'm' type_id=4 bits_offset=0",
> > +             "[6] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
> > +             "\t'p' type_id=3");
>
> [...]
Re: [RFC PATCH v7 2/7] selftests/bpf: Add test cases for btf__permute functionality
Posted by Donglin Peng 1 week, 5 days ago
On Wed, Nov 19, 2025 at 11:21 AM Donglin Peng <dolinux.peng@gmail.com> wrote:
>
> From: Donglin Peng <pengdonglin@xiaomi.com>
>
> This patch introduces test cases for the btf__permute function to ensure
> it works correctly with both base BTF and split BTF scenarios.
>
> The test suite includes:
> - test_permute_base: Validates permutation on base BTF
> - test_permute_split: Tests permutation on split BTF
> - test_permute_drop_base: Validates type dropping on base BTF
> - test_permute_drop_split: Tests type dropping on split BTF
> - test_permute_drop_dedup: Tests type dropping and deduping
>
> Cc: Eduard Zingerman <eddyz87@gmail.com>
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
> Cc: Alan Maguire <alan.maguire@oracle.com>
> Cc: Song Liu <song@kernel.org>
> Cc: Xiaoqin Zhang <zhangxiaoqin@xiaomi.com>
> Signed-off-by: Donglin Peng <pengdonglin@xiaomi.com>
> ---
>  .../selftests/bpf/prog_tests/btf_permute.c    | 608 ++++++++++++++++++
>  1 file changed, 608 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/btf_permute.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/btf_permute.c b/tools/testing/selftests/bpf/prog_tests/btf_permute.c
> new file mode 100644
> index 000000000000..f67bf89519b3
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/btf_permute.c
> @@ -0,0 +1,608 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2025 Xiaomi */
> +
> +#include <test_progs.h>
> +#include <bpf/btf.h>
> +#include "btf_helpers.h"
> +
> +/* Ensure btf__permute work as expected with base BTF */
> +static void test_permute_base(void)
> +{
> +       struct btf *btf;
> +       __u32 permute_ids[6];
> +       int start_id = 1;
> +       int err;
> +
> +       btf = btf__new_empty();
> +       if (!ASSERT_OK_PTR(btf, "empty_main_btf"))
> +               return;
> +
> +       btf__add_int(btf, "int", 4, BTF_INT_SIGNED);    /* [1] int */
> +       btf__add_ptr(btf, 1);                           /* [2] ptr to int */
> +       btf__add_struct(btf, "s1", 4);                  /* [3] struct s1 { */
> +       btf__add_field(btf, "m", 1, 0, 0);              /*       int m; */
> +                                                       /* } */
> +       btf__add_struct(btf, "s2", 4);                  /* [4] struct s2 { */
> +       btf__add_field(btf, "m", 1, 0, 0);              /*       int m; */
> +                                                       /* } */
> +       btf__add_func_proto(btf, 1);                    /* [5] int (*)(int *p); */
> +       btf__add_func_param(btf, "p", 2);
> +       btf__add_func(btf, "f", BTF_FUNC_STATIC, 5);    /* [6] int f(int *p); */
> +
> +       VALIDATE_RAW_BTF(
> +               btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] PTR '(anon)' type_id=1",
> +               "[3] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0",
> +               "[4] STRUCT 's2' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0",
> +               "[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
> +               "\t'p' type_id=2",
> +               "[6] FUNC 'f' type_id=5 linkage=static");
> +
> +       permute_ids[1 - start_id] = 4; /* [1] -> [4] */
> +       permute_ids[2 - start_id] = 3; /* [2] -> [3] */
> +       permute_ids[3 - start_id] = 5; /* [3] -> [5] */
> +       permute_ids[4 - start_id] = 1; /* [4] -> [1] */
> +       permute_ids[5 - start_id] = 6; /* [5] -> [6] */
> +       permute_ids[6 - start_id] = 2; /* [6] -> [2] */
> +       err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
> +       if (!ASSERT_OK(err, "btf__permute_base"))
> +               goto done;
> +
> +       VALIDATE_RAW_BTF(
> +               btf,
> +               "[1] STRUCT 's2' size=4 vlen=1\n"
> +               "\t'm' type_id=4 bits_offset=0",
> +               "[2] FUNC 'f' type_id=6 linkage=static",
> +               "[3] PTR '(anon)' type_id=4",
> +               "[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[5] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=4 bits_offset=0",
> +               "[6] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
> +               "\t'p' type_id=3");
> +
> +       /*
> +        * For base BTF, id_map_cnt must equal to the number of types
> +        * include VOID type
> +        */

My bad. I will remove those comments.

> +       permute_ids[1 - start_id] = 4; /* [1] -> [4] */
> +       permute_ids[2 - start_id] = 3; /* [2] -> [3] */
> +       permute_ids[3 - start_id] = 5; /* [3] -> [5] */
> +       permute_ids[4 - start_id] = 1; /* [4] -> [1] */
> +       permute_ids[5 - start_id] = 6; /* [5] -> [6] */
> +       permute_ids[6 - start_id] = 2; /* [6] -> [2] */
> +       err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids) - 1, NULL);
> +       if (!ASSERT_ERR(err, "btf__permute_base"))
> +               goto done;
> +
> +       VALIDATE_RAW_BTF(
> +               btf,
> +               "[1] STRUCT 's2' size=4 vlen=1\n"
> +               "\t'm' type_id=4 bits_offset=0",
> +               "[2] FUNC 'f' type_id=6 linkage=static",
> +               "[3] PTR '(anon)' type_id=4",
> +               "[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[5] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=4 bits_offset=0",
> +               "[6] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
> +               "\t'p' type_id=3");
> +
> +       /* Multiple types can not be mapped to the same ID */
> +       permute_ids[1 - start_id] = 4;
> +       permute_ids[2 - start_id] = 4;
> +       permute_ids[3 - start_id] = 5;
> +       permute_ids[4 - start_id] = 1;
> +       permute_ids[5 - start_id] = 6;
> +       permute_ids[6 - start_id] = 2;
> +       err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
> +       if (!ASSERT_ERR(err, "btf__permute_base"))
> +               goto done;
> +
> +       VALIDATE_RAW_BTF(
> +               btf,
> +               "[1] STRUCT 's2' size=4 vlen=1\n"
> +               "\t'm' type_id=4 bits_offset=0",
> +               "[2] FUNC 'f' type_id=6 linkage=static",
> +               "[3] PTR '(anon)' type_id=4",
> +               "[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[5] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=4 bits_offset=0",
> +               "[6] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
> +               "\t'p' type_id=3");
> +
> +       /* Type ID must be valid */
> +       permute_ids[1 - start_id] = 4;
> +       permute_ids[2 - start_id] = 3;
> +       permute_ids[3 - start_id] = 5;
> +       permute_ids[4 - start_id] = 1;
> +       permute_ids[5 - start_id] = 7;
> +       permute_ids[6 - start_id] = 2;
> +       err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
> +       if (!ASSERT_ERR(err, "btf__permute_base"))
> +               goto done;
> +
> +       VALIDATE_RAW_BTF(
> +               btf,
> +               "[1] STRUCT 's2' size=4 vlen=1\n"
> +               "\t'm' type_id=4 bits_offset=0",
> +               "[2] FUNC 'f' type_id=6 linkage=static",
> +               "[3] PTR '(anon)' type_id=4",
> +               "[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[5] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=4 bits_offset=0",
> +               "[6] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
> +               "\t'p' type_id=3");
> +
> +done:
> +       btf__free(btf);
> +}
> +
> +/* Ensure btf__permute work as expected with split BTF */
> +static void test_permute_split(void)
> +{
> +       struct btf *split_btf = NULL, *base_btf = NULL;
> +       __u32 permute_ids[4];
> +       int err;
> +       int start_id;
> +
> +       base_btf = btf__new_empty();
> +       if (!ASSERT_OK_PTR(base_btf, "empty_main_btf"))
> +               return;
> +
> +       btf__add_int(base_btf, "int", 4, BTF_INT_SIGNED);       /* [1] int */
> +       btf__add_ptr(base_btf, 1);                              /* [2] ptr to int */
> +       VALIDATE_RAW_BTF(
> +               base_btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] PTR '(anon)' type_id=1");
> +       split_btf = btf__new_empty_split(base_btf);
> +       if (!ASSERT_OK_PTR(split_btf, "empty_split_btf"))
> +               goto cleanup;
> +       btf__add_struct(split_btf, "s1", 4);                    /* [3] struct s1 { */
> +       btf__add_field(split_btf, "m", 1, 0, 0);                /*   int m; */
> +                                                               /* } */
> +       btf__add_struct(split_btf, "s2", 4);                    /* [4] struct s2 { */
> +       btf__add_field(split_btf, "m", 1, 0, 0);                /*   int m; */
> +                                                               /* } */
> +       btf__add_func_proto(split_btf, 1);                      /* [5] int (*)(int p); */
> +       btf__add_func_param(split_btf, "p", 2);
> +       btf__add_func(split_btf, "f", BTF_FUNC_STATIC, 5);      /* [6] int f(int *p); */
> +
> +       VALIDATE_RAW_BTF(
> +               split_btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] PTR '(anon)' type_id=1",
> +               "[3] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0",
> +               "[4] STRUCT 's2' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0",
> +               "[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
> +               "\t'p' type_id=2",
> +               "[6] FUNC 'f' type_id=5 linkage=static");
> +
> +       start_id = btf__type_cnt(base_btf);
> +       permute_ids[3 - start_id] = 6; /* [3] -> [6] */
> +       permute_ids[4 - start_id] = 3; /* [4] -> [3] */
> +       permute_ids[5 - start_id] = 5; /* [5] -> [5] */
> +       permute_ids[6 - start_id] = 4; /* [6] -> [4] */
> +       err = btf__permute(split_btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
> +       if (!ASSERT_OK(err, "btf__permute_split"))
> +               goto cleanup;
> +
> +       VALIDATE_RAW_BTF(
> +               split_btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] PTR '(anon)' type_id=1",
> +               "[3] STRUCT 's2' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0",
> +               "[4] FUNC 'f' type_id=5 linkage=static",
> +               "[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
> +               "\t'p' type_id=2",
> +               "[6] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0");
> +
> +       /*
> +        * For split BTF, id_map_cnt must equal to the number of types
> +        * added on top of base BTF
> +        */
> +       permute_ids[3 - start_id] = 4;
> +       permute_ids[4 - start_id] = 3;
> +       permute_ids[5 - start_id] = 5;
> +       permute_ids[6 - start_id] = 6;
> +       err = btf__permute(split_btf, permute_ids, 3, NULL);
> +       if (!ASSERT_ERR(err, "btf__permute_split"))
> +               goto cleanup;
> +
> +       VALIDATE_RAW_BTF(
> +               split_btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] PTR '(anon)' type_id=1",
> +               "[3] STRUCT 's2' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0",
> +               "[4] FUNC 'f' type_id=5 linkage=static",
> +               "[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
> +               "\t'p' type_id=2",
> +               "[6] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0");
> +
> +       /* Multiple types can not be mapped to the same ID */
> +       permute_ids[3 - start_id] = 4;
> +       permute_ids[4 - start_id] = 3;
> +       permute_ids[5 - start_id] = 3;
> +       permute_ids[6 - start_id] = 6;
> +       err = btf__permute(split_btf, permute_ids, 4, NULL);
> +       if (!ASSERT_ERR(err, "btf__permute_split"))
> +               goto cleanup;
> +
> +       VALIDATE_RAW_BTF(
> +               split_btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] PTR '(anon)' type_id=1",
> +               "[3] STRUCT 's2' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0",
> +               "[4] FUNC 'f' type_id=5 linkage=static",
> +               "[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
> +               "\t'p' type_id=2",
> +               "[6] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0");
> +
> +       /* Can not map to base ID */
> +       permute_ids[3 - start_id] = 4;
> +       permute_ids[4 - start_id] = 2;
> +       permute_ids[5 - start_id] = 5;
> +       permute_ids[6 - start_id] = 6;
> +       err = btf__permute(split_btf, permute_ids, 4, NULL);
> +       if (!ASSERT_ERR(err, "btf__permute_split"))
> +               goto cleanup;
> +
> +       VALIDATE_RAW_BTF(
> +               split_btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] PTR '(anon)' type_id=1",
> +               "[3] STRUCT 's2' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0",
> +               "[4] FUNC 'f' type_id=5 linkage=static",
> +               "[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
> +               "\t'p' type_id=2",
> +               "[6] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0");
> +
> +cleanup:
> +       btf__free(split_btf);
> +       btf__free(base_btf);
> +}
> +
> +/* Verify btf__permute function drops types correctly with base_btf */
> +static void test_permute_drop_base(void)
> +{
> +       struct btf *btf;
> +       __u32 permute_ids[6];
> +       int start_id = 1;
> +       int err;
> +
> +       btf = btf__new_empty();
> +       if (!ASSERT_OK_PTR(btf, "empty_main_btf"))
> +               return;
> +
> +       btf__add_int(btf, "int", 4, BTF_INT_SIGNED);    /* [1] int */
> +       btf__add_ptr(btf, 1);                           /* [2] ptr to int */
> +       btf__add_struct(btf, "s1", 4);                  /* [3] struct s1 { */
> +       btf__add_field(btf, "m", 1, 0, 0);              /*       int m; */
> +                                                       /* } */
> +       btf__add_struct(btf, "s2", 4);                  /* [4] struct s2 { */
> +       btf__add_field(btf, "m", 1, 0, 0);              /*       int m; */
> +                                                       /* } */
> +       btf__add_func_proto(btf, 1);                    /* [5] int (*)(int *p); */
> +       btf__add_func_param(btf, "p", 2);
> +       btf__add_func(btf, "f", BTF_FUNC_STATIC, 5);    /* [6] int f(int *p); */
> +
> +       VALIDATE_RAW_BTF(
> +               btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] PTR '(anon)' type_id=1",
> +               "[3] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0",
> +               "[4] STRUCT 's2' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0",
> +               "[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
> +               "\t'p' type_id=2",
> +               "[6] FUNC 'f' type_id=5 linkage=static");
> +
> +       /* Drop ID 4 */
> +       permute_ids[1 - start_id] = 5; /* [1] -> [5] */
> +       permute_ids[2 - start_id] = 1; /* [2] -> [1] */
> +       permute_ids[3 - start_id] = 2; /* [3] -> [2] */
> +       permute_ids[4 - start_id] = 0; /* Drop [4] */
> +       permute_ids[5 - start_id] = 3; /* [5] -> [3] */
> +       permute_ids[6 - start_id] = 4; /* [6] -> [4] */
> +       err = btf__permute(btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
> +       if (!ASSERT_OK(err, "btf__permute_drop_base"))
> +               goto done;
> +
> +       VALIDATE_RAW_BTF(
> +               btf,
> +               "[1] PTR '(anon)' type_id=5",
> +               "[2] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=5 bits_offset=0",
> +               "[3] FUNC_PROTO '(anon)' ret_type_id=5 vlen=1\n"
> +               "\t'p' type_id=1",
> +               "[4] FUNC 'f' type_id=3 linkage=static",
> +               "[5] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED");
> +
> +       /* Continue dropping */
> +       permute_ids[1 - start_id] = 1; /* [1] -> [1] */
> +       permute_ids[2 - start_id] = 2; /* [2] -> [2] */
> +       permute_ids[3 - start_id] = 3; /* [3] -> [3] */
> +       permute_ids[4 - start_id] = 0; /* Drop [4] */
> +       permute_ids[5 - start_id] = 4; /* [5] -> [4] */
> +       err = btf__permute(btf, permute_ids, 5, NULL);
> +       if (!ASSERT_OK(err, "btf__permute_drop_base_fail"))
> +               goto done;
> +
> +
> +       VALIDATE_RAW_BTF(
> +               btf,
> +               "[1] PTR '(anon)' type_id=4",
> +               "[2] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=4 bits_offset=0",
> +               "[3] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
> +               "\t'p' type_id=1",
> +               "[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED");
> +
> +       /* Cannot drop the ID referenced by others */
> +       permute_ids[1 - start_id] = 2;
> +       permute_ids[2 - start_id] = 3;
> +       permute_ids[3 - start_id] = 1;
> +       permute_ids[4 - start_id] = 0; /* [4] is referenced by others */
> +       err = btf__permute(btf, permute_ids, 4, NULL);
> +       if (!ASSERT_ERR(err, "btf__permute_drop_base_fail"))
> +               goto done;
> +
> +       VALIDATE_RAW_BTF(
> +               btf,
> +               "[1] PTR '(anon)' type_id=4",
> +               "[2] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=4 bits_offset=0",
> +               "[3] FUNC_PROTO '(anon)' ret_type_id=4 vlen=1\n"
> +               "\t'p' type_id=1",
> +               "[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED");
> +
> +       /* Drop 2 IDs at once */
> +       permute_ids[1 - start_id] = 2; /* [1] -> [2] */
> +       permute_ids[2 - start_id] = 0; /* Drop [2] */
> +       permute_ids[3 - start_id] = 0; /* Drop [3] */
> +       permute_ids[4 - start_id] = 1; /* [4] -> [1] */
> +       err = btf__permute(btf, permute_ids, 4, NULL);
> +       if (!ASSERT_OK(err, "btf__permute_drop_base_fail"))
> +               goto done;
> +
> +       VALIDATE_RAW_BTF(
> +               btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] PTR '(anon)' type_id=1");
> +
> +       /* Drop all IDs */
> +       permute_ids[1 - start_id] = 0; /* Drop [1] */
> +       permute_ids[2 - start_id] = 0; /* Drop [2] */
> +       err = btf__permute(btf, permute_ids, 2, NULL);
> +       if (!ASSERT_OK(err, "btf__permute_drop_base_fail"))
> +               goto done;
> +       if (!ASSERT_EQ(btf__type_cnt(btf), 1, "btf__permute_drop_base all"))
> +               goto done;
> +
> +done:
> +       btf__free(btf);
> +}
> +
> +/* Verify btf__permute function drops types correctly with split BTF */
> +static void test_permute_drop_split(void)
> +{
> +       struct btf *split_btf = NULL, *base_btf = NULL;
> +       __u32 permute_ids[4];
> +       int err;
> +       int start_id;
> +
> +       base_btf = btf__new_empty();
> +       if (!ASSERT_OK_PTR(base_btf, "empty_main_btf"))
> +               return;
> +
> +       btf__add_int(base_btf, "int", 4, BTF_INT_SIGNED);       /* [1] int */
> +       btf__add_ptr(base_btf, 1);                              /* [2] ptr to int */
> +       VALIDATE_RAW_BTF(
> +               base_btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] PTR '(anon)' type_id=1");
> +       split_btf = btf__new_empty_split(base_btf);
> +       if (!ASSERT_OK_PTR(split_btf, "empty_split_btf"))
> +               goto cleanup;
> +       btf__add_struct(split_btf, "s1", 4);                    /* [3] struct s1 { */
> +       btf__add_field(split_btf, "m", 1, 0, 0);                /*   int m; */
> +                                                               /* } */
> +       btf__add_struct(split_btf, "s2", 4);                    /* [4] struct s2 { */
> +       btf__add_field(split_btf, "m", 1, 0, 0);                /*   int m; */
> +                                                               /* } */
> +       btf__add_func_proto(split_btf, 1);                      /* [5] int (*)(int p); */
> +       btf__add_func_param(split_btf, "p", 2);
> +       btf__add_func(split_btf, "f", BTF_FUNC_STATIC, 5);      /* [6] int f(int *p); */
> +
> +       VALIDATE_RAW_BTF(
> +               split_btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] PTR '(anon)' type_id=1",
> +               "[3] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0",
> +               "[4] STRUCT 's2' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0",
> +               "[5] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
> +               "\t'p' type_id=2",
> +               "[6] FUNC 'f' type_id=5 linkage=static");
> +
> +       start_id = btf__type_cnt(base_btf);
> +
> +       /* Drop ID 4 */
> +       permute_ids[3 - start_id] = 5; /* [3] -> [5] */
> +       permute_ids[4 - start_id] = 0; /* Drop [4] */
> +       permute_ids[5 - start_id] = 3; /* [5] -> [3] */
> +       permute_ids[6 - start_id] = 4; /* [6] -> [4] */
> +       err = btf__permute(split_btf, permute_ids, ARRAY_SIZE(permute_ids), NULL);
> +       if (!ASSERT_OK(err, "btf__permute_drop_split"))
> +               goto cleanup;
> +
> +       VALIDATE_RAW_BTF(
> +               split_btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] PTR '(anon)' type_id=1",
> +               "[3] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
> +               "\t'p' type_id=2",
> +               "[4] FUNC 'f' type_id=3 linkage=static",
> +               "[5] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0");
> +
> +       /* Can not drop the type referenced by others */
> +       permute_ids[3 - start_id] = 0; /* [3] is referenced by [4] */
> +       permute_ids[4 - start_id] = 4;
> +       permute_ids[5 - start_id] = 3;
> +       err = btf__permute(split_btf, permute_ids, 3, NULL);
> +       if (!ASSERT_ERR(err, "btf__permute_drop_split"))
> +               goto cleanup;
> +
> +       VALIDATE_RAW_BTF(
> +               split_btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] PTR '(anon)' type_id=1",
> +               "[3] FUNC_PROTO '(anon)' ret_type_id=1 vlen=1\n"
> +               "\t'p' type_id=2",
> +               "[4] FUNC 'f' type_id=3 linkage=static",
> +               "[5] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0");
> +
> +       /* Continue dropping */
> +       permute_ids[3 - start_id] = 0; /* Drop [3] */
> +       permute_ids[4 - start_id] = 0; /* Drop [4] */
> +       permute_ids[5 - start_id] = 3; /* [5] -> [3] */
> +       err = btf__permute(split_btf, permute_ids, 3, NULL);
> +       if (!ASSERT_OK(err, "btf__permute_drop_split"))
> +               goto cleanup;
> +
> +       VALIDATE_RAW_BTF(
> +               split_btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] PTR '(anon)' type_id=1",
> +               "[3] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0");
> +
> +       /* Continue dropping */
> +       permute_ids[3 - start_id] = 0; /* Drop [3] */
> +       err = btf__permute(split_btf, permute_ids, 1, NULL);
> +       if (!ASSERT_OK(err, "btf__permute_drop_split"))
> +               goto cleanup;
> +
> +       VALIDATE_RAW_BTF(
> +               split_btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] PTR '(anon)' type_id=1");
> +
> +cleanup:
> +       btf__free(split_btf);
> +       btf__free(base_btf);
> +}
> +
> +/* Verify btf__permute then btf__dedup work correctly */
> +static void test_permute_drop_dedup(void)
> +{
> +       struct btf *btf, *new_btf = NULL;
> +       const struct btf_header *hdr;
> +       const void *btf_data;
> +       char expect_strs[] = "\0int\0s1\0m\0tag1\0tag2\0tag3";
> +       char expect_strs_dedupped[] = "\0int\0s1\0m\0tag1";
> +       __u32 permute_ids[5], btf_size;
> +       int start_id = 1;
> +       int err;
> +
> +       btf = btf__new_empty();
> +       if (!ASSERT_OK_PTR(btf, "empty_main_btf"))
> +               return;
> +
> +       btf__add_int(btf, "int", 4, BTF_INT_SIGNED);    /* [1] int */
> +       btf__add_struct(btf, "s1", 4);                  /* [2] struct s1 { */
> +       btf__add_field(btf, "m", 1, 0, 0);              /*       int m; */
> +                                                       /* } */
> +       btf__add_decl_tag(btf, "tag1", 2, -1);          /* [3] tag -> s1: tag1 */
> +       btf__add_decl_tag(btf, "tag2", 2, 1);           /* [4] tag -> s1/m: tag2 */
> +       btf__add_decl_tag(btf, "tag3", 2, 1);           /* [5] tag -> s1/m: tag3 */
> +
> +       VALIDATE_RAW_BTF(
> +               btf,
> +               "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> +               "[2] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=1 bits_offset=0",
> +               "[3] DECL_TAG 'tag1' type_id=2 component_idx=-1",
> +               "[4] DECL_TAG 'tag2' type_id=2 component_idx=1",
> +               "[5] DECL_TAG 'tag3' type_id=2 component_idx=1");
> +
> +       btf_data = btf__raw_data(btf, &btf_size);
> +       if (!ASSERT_OK_PTR(btf_data, "btf__raw_data"))
> +               goto done;
> +       hdr = btf_data;
> +       if (!ASSERT_EQ(hdr->str_len, ARRAY_SIZE(expect_strs), "expect_strs"))
> +               goto done;
> +
> +       new_btf = btf__new(btf_data, btf_size);
> +       if (!ASSERT_OK_PTR(new_btf, "btf__new"))
> +               goto done;
> +
> +       /* Drop 2 IDs result in unreferenced strings */
> +       permute_ids[1 - start_id] = 3; /* [1] -> [3] */
> +       permute_ids[2 - start_id] = 1; /* [2] -> [1] */
> +       permute_ids[3 - start_id] = 2; /* [3] -> [2] */
> +       permute_ids[4 - start_id] = 0; /* Drop result in unreferenced "tag2" */
> +       permute_ids[5 - start_id] = 0; /* Drop result in unreferenced "tag3" */
> +       err = btf__permute(new_btf, permute_ids, 5, NULL);
> +       if (!ASSERT_OK(err, "btf__permute"))
> +               goto done;
> +
> +       VALIDATE_RAW_BTF(
> +               new_btf,
> +               "[1] STRUCT 's1' size=4 vlen=1\n"
> +               "\t'm' type_id=3 bits_offset=0",
> +               "[2] DECL_TAG 'tag1' type_id=1 component_idx=-1",
> +               "[3] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED");
> +
> +       btf_data = btf__raw_data(new_btf, &btf_size);
> +       if (!ASSERT_OK_PTR(btf_data, "btf__raw_data"))
> +               goto done;
> +       hdr = btf_data;
> +       if (!ASSERT_EQ(hdr->str_len, ARRAY_SIZE(expect_strs), "expect_strs"))
> +               goto done;
> +
> +       err = btf__dedup(new_btf, NULL);
> +       if (!ASSERT_OK(err, "btf__dedup"))
> +               goto done;
> +
> +       btf_data = btf__raw_data(new_btf, &btf_size);
> +       if (!ASSERT_OK_PTR(btf_data, "btf__raw_data"))
> +               goto done;
> +       hdr = btf_data;
> +       if (!ASSERT_EQ(hdr->str_len, ARRAY_SIZE(expect_strs_dedupped), "expect_strs_dedupped"))
> +               goto done;
> +
> +done:
> +       btf__free(btf);
> +       btf__free(new_btf);
> +}
> +
> +void test_btf_permute(void)
> +{
> +       if (test__start_subtest("permute_base"))
> +               test_permute_base();
> +       if (test__start_subtest("permute_split"))
> +               test_permute_split();
> +       if (test__start_subtest("permute_drop_base"))
> +               test_permute_drop_base();
> +       if (test__start_subtest("permute_drop_split"))
> +               test_permute_drop_split();
> +       if (test__start_subtest("permute_drop_dedup"))
> +               test_permute_drop_dedup();
> +}
> --
> 2.34.1
>