diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 00a2f06e38fd994446cae085be386281b16a7353..1b8d8cdd35750f7b9fc4f2fffb044f300e6bade9 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -1070,8 +1070,8 @@ int btf__dedup(struct btf *btf, struct btf_ext *btf_ext,
return err;
}
-#define BTF_DEDUP_TABLE_SIZE_LOG 14
-#define BTF_DEDUP_TABLE_MOD ((1 << BTF_DEDUP_TABLE_SIZE_LOG) - 1)
+#define BTF_DEDUP_TABLE_DEFAULT_SIZE (1 << 14)
+#define BTF_DEDUP_TABLE_MAX_SIZE_LOG 31
#define BTF_UNPROCESSED_ID ((__u32)-1)
#define BTF_IN_PROGRESS_ID ((__u32)-2)
@@ -1128,18 +1128,21 @@ static inline __u32 hash_combine(__u32 h, __u32 value)
#undef GOLDEN_RATIO_PRIME
}
-#define for_each_hash_node(table, hash, node) \
- for (node = table[hash & BTF_DEDUP_TABLE_MOD]; node; node = node->next)
+#define for_each_dedup_cand(d, hash, node) \
+ for (node = d->dedup_table[hash & (d->opts.dedup_table_size - 1)]; \
+ node; \
+ node = node->next)
static int btf_dedup_table_add(struct btf_dedup *d, __u32 hash, __u32 type_id)
{
struct btf_dedup_node *node = malloc(sizeof(struct btf_dedup_node));
+ int bucket = hash & (d->opts.dedup_table_size - 1);
if (!node)
return -ENOMEM;
node->type_id = type_id;
- node->next = d->dedup_table[hash & BTF_DEDUP_TABLE_MOD];
- d->dedup_table[hash & BTF_DEDUP_TABLE_MOD] = node;
+ node->next = d->dedup_table[bucket];
+ d->dedup_table[bucket] = node;
return 0;
}
@@ -1177,7 +1180,7 @@ static void btf_dedup_table_free(struct btf_dedup *d)
if (!d->dedup_table)
return;
- for (i = 0; i < (1 << BTF_DEDUP_TABLE_SIZE_LOG); i++) {
+ for (i = 0; i < d->opts.dedup_table_size; i++) {
while (d->dedup_table[i]) {
tmp = d->dedup_table[i];
d->dedup_table[i] = tmp->next;
@@ -1212,19 +1215,37 @@ static void btf_dedup_free(struct btf_dedup *d)
free(d);
}
+/* Find closest power of two >= to size, capped at 2^max_size_log */
+static __u32 roundup_pow2_max(__u32 size, int max_size_log)
+{
+ int i;
+
+ for (i = 0; i < max_size_log && (1U << i) < size; i++)
+ ;
+ return 1U << i;
+}
+
+
static struct btf_dedup *btf_dedup_new(struct btf *btf, struct btf_ext *btf_ext,
const struct btf_dedup_opts *opts)
{
struct btf_dedup *d = calloc(1, sizeof(struct btf_dedup));
int i, err = 0;
+ __u32 sz;
if (!d)
return ERR_PTR(-ENOMEM);
+ d->opts.dont_resolve_fwds = opts && opts->dont_resolve_fwds;
+ sz = opts && opts->dedup_table_size ? opts->dedup_table_size
+ : BTF_DEDUP_TABLE_DEFAULT_SIZE;
+ sz = roundup_pow2_max(sz, BTF_DEDUP_TABLE_MAX_SIZE_LOG);
+ d->opts.dedup_table_size = sz;
+
d->btf = btf;
d->btf_ext = btf_ext;
- d->dedup_table = calloc(1 << BTF_DEDUP_TABLE_SIZE_LOG,
+ d->dedup_table = calloc(d->opts.dedup_table_size,
sizeof(struct btf_dedup_node *));
if (!d->dedup_table) {
err = -ENOMEM;
@@ -1249,8 +1270,6 @@ static struct btf_dedup *btf_dedup_new(struct btf *btf, struct btf_ext *btf_ext,
for (i = 0; i <= btf->nr_types; i++)
d->hypot_map[i] = BTF_UNPROCESSED_ID;
- d->opts.dont_resolve_fwds = opts && opts->dont_resolve_fwds;
-
done:
if (err) {
btf_dedup_free(d);
@@ -1644,7 +1663,7 @@ static __u32 btf_hash_struct(struct btf_type *t)
* IDs. This check is performed during type graph equivalence check and
* referenced types equivalence is checked separately.
*/
-static bool btf_equal_struct(struct btf_type *t1, struct btf_type *t2)
+static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2)
{
struct btf_member *m1, *m2;
__u16 vlen;
@@ -1824,7 +1843,7 @@ static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
case BTF_KIND_INT:
h = btf_hash_int(t);
- for_each_hash_node(d->dedup_table, h, cand_node) {
+ for_each_dedup_cand(d, h, cand_node) {
cand = d->btf->types[cand_node->type_id];
if (btf_equal_int(t, cand)) {
new_id = cand_node->type_id;
@@ -1835,7 +1854,7 @@ static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
case BTF_KIND_ENUM:
h = btf_hash_enum(t);
- for_each_hash_node(d->dedup_table, h, cand_node) {
+ for_each_dedup_cand(d, h, cand_node) {
cand = d->btf->types[cand_node->type_id];
if (btf_equal_enum(t, cand)) {
new_id = cand_node->type_id;
@@ -1846,7 +1865,7 @@ static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
case BTF_KIND_FWD:
h = btf_hash_common(t);
- for_each_hash_node(d->dedup_table, h, cand_node) {
+ for_each_dedup_cand(d, h, cand_node) {
cand = d->btf->types[cand_node->type_id];
if (btf_equal_common(t, cand)) {
new_id = cand_node->type_id;
@@ -2105,7 +2124,7 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
struct btf_member *cand_m, *canon_m;
__u16 vlen;
- if (!btf_equal_struct(cand_type, canon_type))
+ if (!btf_shallow_equal_struct(cand_type, canon_type))
return 0;
vlen = BTF_INFO_VLEN(cand_type->info);
cand_m = (struct btf_member *)(cand_type + 1);
@@ -2246,7 +2265,7 @@ static void btf_dedup_merge_hypot_map(struct btf_dedup *d)
static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id)
{
struct btf_dedup_node *cand_node;
- struct btf_type *t;
+ struct btf_type *cand_type, *t;
/* if we don't find equivalent type, then we are canonical */
__u32 new_id = type_id;
__u16 kind;
@@ -2263,9 +2282,23 @@ static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id)
return 0;
h = btf_hash_struct(t);
- for_each_hash_node(d->dedup_table, h, cand_node) {
+ for_each_dedup_cand(d, h, cand_node) {
int eq;
+ /*
+ * Even though btf_dedup_is_equiv() checks for
+ * btf_shallow_equal_struct() internally when checking two
+ * structs (unions) for equivalence, we need to guard here
+ * from picking matching FWD type as a dedup candidate.
+ * This can happen due to hash collision. In such case just
+ * relying on btf_dedup_is_equiv() would lead to potentially
+ * creating a loop (FWD -> STRUCT and STRUCT -> FWD), because
+ * FWD and compatible STRUCT/UNION are considered equivalent.
+ */
+ cand_type = d->btf->types[cand_node->type_id];
+ if (!btf_shallow_equal_struct(t, cand_type))
+ continue;
+
btf_dedup_clear_hypot_map(d);
eq = btf_dedup_is_equiv(d, type_id, cand_node->type_id);
if (eq < 0)
@@ -2350,7 +2383,7 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
t->type = ref_type_id;
h = btf_hash_common(t);
- for_each_hash_node(d->dedup_table, h, cand_node) {
+ for_each_dedup_cand(d, h, cand_node) {
cand = d->btf->types[cand_node->type_id];
if (btf_equal_common(t, cand)) {
new_id = cand_node->type_id;
@@ -2373,7 +2406,7 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
info->index_type = ref_type_id;
h = btf_hash_array(t);
- for_each_hash_node(d->dedup_table, h, cand_node) {
+ for_each_dedup_cand(d, h, cand_node) {
cand = d->btf->types[cand_node->type_id];
if (btf_equal_array(t, cand)) {
new_id = cand_node->type_id;
@@ -2404,7 +2437,7 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
}
h = btf_hash_fnproto(t);
- for_each_hash_node(d->dedup_table, h, cand_node) {
+ for_each_dedup_cand(d, h, cand_node) {
cand = d->btf->types[cand_node->type_id];
if (btf_equal_fnproto(t, cand)) {
new_id = cand_node->type_id;
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 94bbc249b0f1ddcbeb8dc7504fc29dc2449e8041..28a1e1e59861927dc31783b74ee11be302667f32 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -76,7 +76,7 @@ LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
LIBBPF_API struct btf_ext *btf_ext__new(__u8 *data, __u32 size);
LIBBPF_API void btf_ext__free(struct btf_ext *btf_ext);
-LIBBPF_API const void *btf_ext__get_raw_data(const struct btf_ext* btf_ext,
+LIBBPF_API const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext,
__u32 *size);
LIBBPF_API int btf_ext__reloc_func_info(const struct btf *btf,
const struct btf_ext *btf_ext,
@@ -90,6 +90,7 @@ LIBBPF_API __u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext);
LIBBPF_API __u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext);
struct btf_dedup_opts {
+ unsigned int dedup_table_size;
bool dont_resolve_fwds;
};
diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
index e47168d1257d9437f5a84fe8daf10b83a19bd091..3b74d23fffabe46e5fac0f78b4c28be5dce6d13c 100644
--- a/tools/testing/selftests/bpf/.gitignore
+++ b/tools/testing/selftests/bpf/.gitignore
@@ -14,6 +14,7 @@ feature
test_libbpf_open
test_sock
test_sock_addr
+test_sock_fields
urandom_read
test_btf
test_sockmap
diff --git a/tools/testing/selftests/bpf/test_btf.c b/tools/testing/selftests/bpf/test_btf.c
index 02d314383a9c8fae85b318807921a9a59f78fb7e..38797aa627a732f31d333aaa6cf8020ceb3a211d 100644
--- a/tools/testing/selftests/bpf/test_btf.c
+++ b/tools/testing/selftests/bpf/test_btf.c
@@ -5731,6 +5731,51 @@ const struct btf_dedup_test dedup_tests[] = {
.dont_resolve_fwds = false,
},
},
+{
+ .descr = "dedup: struct <-> fwd resolution w/ hash collision",
+ /*
+ * // CU 1:
+ * struct x;
+ * struct s {
+ * struct x *x;
+ * };
+ * // CU 2:
+ * struct x {};
+ * struct s {
+ * struct x *x;
+ * };
+ */
+ .input = {
+ .raw_types = {
+ /* CU 1 */
+ BTF_FWD_ENC(NAME_TBD, 0 /* struct fwd */), /* [1] fwd x */
+ BTF_PTR_ENC(1), /* [2] ptr -> [1] */
+ BTF_STRUCT_ENC(NAME_TBD, 1, 8), /* [3] struct s */
+ BTF_MEMBER_ENC(NAME_TBD, 2, 0),
+ /* CU 2 */
+ BTF_STRUCT_ENC(NAME_TBD, 0, 0), /* [4] struct x */
+ BTF_PTR_ENC(4), /* [5] ptr -> [4] */
+ BTF_STRUCT_ENC(NAME_TBD, 1, 8), /* [6] struct s */
+ BTF_MEMBER_ENC(NAME_TBD, 5, 0),
+ BTF_END_RAW,
+ },
+ BTF_STR_SEC("\0x\0s\0x\0x\0s\0x\0"),
+ },
+ .expect = {
+ .raw_types = {
+ BTF_PTR_ENC(3), /* [1] ptr -> [3] */
+ BTF_STRUCT_ENC(NAME_TBD, 1, 8), /* [2] struct s */
+ BTF_MEMBER_ENC(NAME_TBD, 1, 0),
+ BTF_STRUCT_ENC(NAME_NTH(2), 0, 0), /* [3] struct x */
+ BTF_END_RAW,
+ },
+ BTF_STR_SEC("\0s\0x"),
+ },
+ .opts = {
+ .dont_resolve_fwds = false,
+ .dedup_table_size = 1, /* force hash collisions */
+ },
+},
{
.descr = "dedup: all possible kinds (no duplicates)",
.input = {
@@ -5936,9 +5981,9 @@ static int do_test_dedup(unsigned int test_num)
}
test_hdr = test_btf_data;
- test_strs = test_btf_data + test_hdr->str_off;
+ test_strs = test_btf_data + sizeof(*test_hdr) + test_hdr->str_off;
expect_hdr = expect_btf_data;
- expect_strs = expect_btf_data + expect_hdr->str_off;
+ expect_strs = expect_btf_data + sizeof(*test_hdr) + expect_hdr->str_off;
if (CHECK(test_hdr->str_len != expect_hdr->str_len,
"test_hdr->str_len:%u != expect_hdr->str_len:%u",
test_hdr->str_len, expect_hdr->str_len)) {