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

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (c) 2020 Facebook */
   3 #define _GNU_SOURCE
   4 #include <string.h>
   5 #include <byteswap.h>
   6 #include <test_progs.h>
   7 #include <bpf/btf.h>
   8
   9 static int duration = 0;
  10
  11 void test_btf_endian() {
  12 #if __BYTE_ORDER == __LITTLE_ENDIAN
  13         enum btf_endianness endian = BTF_LITTLE_ENDIAN;
  14 #elif __BYTE_ORDER == __BIG_ENDIAN
  15         enum btf_endianness endian = BTF_BIG_ENDIAN;
  16 #else
  17 #error "Unrecognized __BYTE_ORDER"
  18 #endif
  19         enum btf_endianness swap_endian = 1 - endian;
  20         struct btf *btf = NULL, *swap_btf = NULL;
  21         const void *raw_data, *swap_raw_data;
  22         const struct btf_type *t;
  23         const struct btf_header *hdr;
  24         __u32 raw_sz, swap_raw_sz;
  25         int var_id;
  26
  27         /* Load BTF in native endianness */
  28         btf = btf__parse_elf("btf_dump_test_case_syntax.o", NULL);
  29         if (!ASSERT_OK_PTR(btf, "parse_native_btf"))
  30                 goto err_out;
  31
  32         ASSERT_EQ(btf__endianness(btf), endian, "endian");
  33         btf__set_endianness(btf, swap_endian);
  34         ASSERT_EQ(btf__endianness(btf), swap_endian, "endian");
  35
  36         /* Get raw BTF data in non-native endianness... */
  37         raw_data = btf__get_raw_data(btf, &raw_sz);
  38         if (!ASSERT_OK_PTR(raw_data, "raw_data_inverted"))
  39                 goto err_out;
  40
  41         /* ...and open it as a new BTF instance */
  42         swap_btf = btf__new(raw_data, raw_sz);
  43         if (!ASSERT_OK_PTR(swap_btf, "parse_swap_btf"))
  44                 goto err_out;
  45
  46         ASSERT_EQ(btf__endianness(swap_btf), swap_endian, "endian");
  47         ASSERT_EQ(btf__get_nr_types(swap_btf), btf__get_nr_types(btf), "nr_types");
  48
  49         swap_raw_data = btf__get_raw_data(swap_btf, &swap_raw_sz);
  50         if (!ASSERT_OK_PTR(swap_raw_data, "swap_raw_data"))
  51                 goto err_out;
  52
  53         /* both raw data should be identical (with non-native endianness) */
  54         ASSERT_OK(memcmp(raw_data, swap_raw_data, raw_sz), "mem_identical");
  55
  56         /* make sure that at least BTF header data is really swapped */
  57         hdr = swap_raw_data;
  58         ASSERT_EQ(bswap_16(hdr->magic), BTF_MAGIC, "btf_magic_swapped");
  59         ASSERT_EQ(raw_sz, swap_raw_sz, "raw_sizes");
  60
  61         /* swap it back to native endianness */
  62         btf__set_endianness(swap_btf, endian);
  63         swap_raw_data = btf__get_raw_data(swap_btf, &swap_raw_sz);
  64         if (!ASSERT_OK_PTR(swap_raw_data, "swap_raw_data"))
  65                 goto err_out;
  66
  67         /* now header should have native BTF_MAGIC */
  68         hdr = swap_raw_data;
  69         ASSERT_EQ(hdr->magic, BTF_MAGIC, "btf_magic_native");
  70         ASSERT_EQ(raw_sz, swap_raw_sz, "raw_sizes");
  71
  72         /* now modify original BTF */
  73         var_id = btf__add_var(btf, "some_var", BTF_VAR_GLOBAL_ALLOCATED, 1);
  74         CHECK(var_id <= 0, "var_id", "failed %d\n", var_id);
  75
  76         btf__free(swap_btf);
  77         swap_btf = NULL;
  78
  79         btf__set_endianness(btf, swap_endian);
  80         raw_data = btf__get_raw_data(btf, &raw_sz);
  81         if (!ASSERT_OK_PTR(raw_data, "raw_data_inverted"))
  82                 goto err_out;
  83
  84         /* and re-open swapped raw data again */
  85         swap_btf = btf__new(raw_data, raw_sz);
  86         if (!ASSERT_OK_PTR(swap_btf, "parse_swap_btf"))
  87                 goto err_out;
  88
  89         ASSERT_EQ(btf__endianness(swap_btf), swap_endian, "endian");
  90         ASSERT_EQ(btf__get_nr_types(swap_btf), btf__get_nr_types(btf), "nr_types");
  91
  92         /* the type should appear as if it was stored in native endianness */
  93         t = btf__type_by_id(swap_btf, var_id);
  94         ASSERT_STREQ(btf__str_by_offset(swap_btf, t->name_off), "some_var", "var_name");
  95         ASSERT_EQ(btf_var(t)->linkage, BTF_VAR_GLOBAL_ALLOCATED, "var_linkage");
  96         ASSERT_EQ(t->type, 1, "var_type");
  97
  98 err_out:
  99         btf__free(btf);
 100         btf__free(swap_btf);
 101 }