diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 89fecfe5cb2b307d8bb2d10e1f81406a87f4096b..fa1b147c63c61f3bca3bd39c3732e1f8af394967 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -90,6 +90,14 @@ struct btf {
struct hashmap *strs_hash;
/* whether strings are already deduplicated */
bool strs_deduped;
+ /* extra indirection layer to make strings hashmap work with stable
+ * string offsets and ability to transparently choose between
+ * btf->strs_data or btf_dedup->strs_data as a source of strings.
+ * This is used for BTF strings dedup to transfer deduplicated strings
+ * data back to struct btf without re-building strings index.
+ */
+ void **strs_data_ptr;
+
/* BTF object FD, if loaded into kernel */
int fd;
@@ -1363,17 +1371,19 @@ int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
static size_t strs_hash_fn(const void *key, void *ctx)
{
- struct btf *btf = ctx;
- const char *str = btf->strs_data + (long)key;
+ const struct btf *btf = ctx;
+ const char *strs = *btf->strs_data_ptr;
+ const char *str = strs + (long)key;
return str_hash(str);
}
static bool strs_hash_equal_fn(const void *key1, const void *key2, void *ctx)
{
- struct btf *btf = ctx;
- const char *str1 = btf->strs_data + (long)key1;
- const char *str2 = btf->strs_data + (long)key2;
+ const struct btf *btf = ctx;
+ const char *strs = *btf->strs_data_ptr;
+ const char *str1 = strs + (long)key1;
+ const char *str2 = strs + (long)key2;
return strcmp(str1, str2) == 0;
}
@@ -1418,6 +1428,9 @@ static int btf_ensure_modifiable(struct btf *btf)
memcpy(types, btf->types_data, btf->hdr->type_len);
memcpy(strs, btf->strs_data, btf->hdr->str_len);
+ /* make hashmap below use btf->strs_data as a source of strings */
+ btf->strs_data_ptr = &btf->strs_data;
+
/* build lookup index for all strings */
hash = hashmap__new(strs_hash_fn, strs_hash_equal_fn, btf);
if (IS_ERR(hash)) {
@@ -2824,19 +2837,11 @@ struct btf_dedup {
size_t hypot_cap;
/* Various option modifying behavior of algorithm */
struct btf_dedup_opts opts;
-};
-
-struct btf_str_ptr {
- const char *str;
- __u32 new_off;
- bool used;
-};
-
-struct btf_str_ptrs {
- struct btf_str_ptr *ptrs;
- const char *data;
- __u32 cnt;
- __u32 cap;
+ /* temporary strings deduplication state */
+ void *strs_data;
+ size_t strs_cap;
+ size_t strs_len;
+ struct hashmap* strs_hash;
};
static long hash_combine(long h, long value)
@@ -3063,64 +3068,41 @@ static int btf_for_each_str_off(struct btf_dedup *d, str_off_fn_t fn, void *ctx)
return 0;
}
-static int str_sort_by_content(const void *a1, const void *a2)
-{
- const struct btf_str_ptr *p1 = a1;
- const struct btf_str_ptr *p2 = a2;
-
- return strcmp(p1->str, p2->str);
-}
-
-static int str_sort_by_offset(const void *a1, const void *a2)
-{
- const struct btf_str_ptr *p1 = a1;
- const struct btf_str_ptr *p2 = a2;
-
- if (p1->str != p2->str)
- return p1->str < p2->str ? -1 : 1;
- return 0;
-}
-
-static int btf_dedup_str_ptr_cmp(const void *str_ptr, const void *pelem)
-{
- const struct btf_str_ptr *p = pelem;
-
- if (str_ptr != p->str)
- return (const char *)str_ptr < p->str ? -1 : 1;
- return 0;
-}
-
-static int btf_str_mark_as_used(__u32 *str_off_ptr, void *ctx)
+static int strs_dedup_remap_str_off(__u32 *str_off_ptr, void *ctx)
{
- struct btf_str_ptrs *strs;
- struct btf_str_ptr *s;
+ struct btf_dedup *d = ctx;
+ long old_off, new_off, len;
+ const char *s;
+ void *p;
+ int err;
if (*str_off_ptr == 0)
return 0;
- strs = ctx;
- s = bsearch(strs->data + *str_off_ptr, strs->ptrs, strs->cnt,
- sizeof(struct btf_str_ptr), btf_dedup_str_ptr_cmp);
- if (!s)
- return -EINVAL;
- s->used = true;
- return 0;
-}
+ s = btf__str_by_offset(d->btf, *str_off_ptr);
+ len = strlen(s) + 1;
-static int btf_str_remap_offset(__u32 *str_off_ptr, void *ctx)
-{
- struct btf_str_ptrs *strs;
- struct btf_str_ptr *s;
+ new_off = d->strs_len;
+ p = btf_add_mem(&d->strs_data, &d->strs_cap, 1, new_off, BTF_MAX_STR_OFFSET, len);
+ if (!p)
+ return -ENOMEM;
- if (*str_off_ptr == 0)
- return 0;
+ memcpy(p, s, len);
- strs = ctx;
- s = bsearch(strs->data + *str_off_ptr, strs->ptrs, strs->cnt,
- sizeof(struct btf_str_ptr), btf_dedup_str_ptr_cmp);
- if (!s)
- return -EINVAL;
- *str_off_ptr = s->new_off;
+ /* Now attempt to add the string, but only if the string with the same
+ * contents doesn't exist already (HASHMAP_ADD strategy). If such
+ * string exists, we'll get its offset in old_off (that's old_key).
+ */
+ err = hashmap__insert(d->strs_hash, (void *)new_off, (void *)new_off,
+ HASHMAP_ADD, (const void **)&old_off, NULL);
+ if (err == -EEXIST) {
+ *str_off_ptr = old_off;
+ } else if (err) {
+ return err;
+ } else {
+ *str_off_ptr = new_off;
+ d->strs_len += len;
+ }
return 0;
}
@@ -3137,118 +3119,69 @@ static int btf_str_remap_offset(__u32 *str_off_ptr, void *ctx)
*/
static int btf_dedup_strings(struct btf_dedup *d)
{
- char *start = d->btf->strs_data;
- char *end = start + d->btf->hdr->str_len;
- char *p = start, *tmp_strs = NULL;
- struct btf_str_ptrs strs = {
- .cnt = 0,
- .cap = 0,
- .ptrs = NULL,
- .data = start,
- };
- int i, j, err = 0, grp_idx;
- bool grp_used;
+ char *s;
+ int err;
if (d->btf->strs_deduped)
return 0;
- /* build index of all strings */
- while (p < end) {
- if (strs.cnt + 1 > strs.cap) {
- struct btf_str_ptr *new_ptrs;
-
- strs.cap += max(strs.cnt / 2, 16U);
- new_ptrs = libbpf_reallocarray(strs.ptrs, strs.cap, sizeof(strs.ptrs[0]));
- if (!new_ptrs) {
- err = -ENOMEM;
- goto done;
- }
- strs.ptrs = new_ptrs;
- }
-
- strs.ptrs[strs.cnt].str = p;
- strs.ptrs[strs.cnt].used = false;
-
- p += strlen(p) + 1;
- strs.cnt++;
- }
-
- /* temporary storage for deduplicated strings */
- tmp_strs = malloc(d->btf->hdr->str_len);
- if (!tmp_strs) {
- err = -ENOMEM;
- goto done;
- }
-
- /* mark all used strings */
- strs.ptrs[0].used = true;
- err = btf_for_each_str_off(d, btf_str_mark_as_used, &strs);
- if (err)
- goto done;
-
- /* sort strings by context, so that we can identify duplicates */
- qsort(strs.ptrs, strs.cnt, sizeof(strs.ptrs[0]), str_sort_by_content);
+ s = btf_add_mem(&d->strs_data, &d->strs_cap, 1, d->strs_len, BTF_MAX_STR_OFFSET, 1);
+ if (!s)
+ return -ENOMEM;
+ /* initial empty string */
+ s[0] = 0;
+ d->strs_len = 1;
- /*
- * iterate groups of equal strings and if any instance in a group was
- * referenced, emit single instance and remember new offset
+ /* temporarily switch to use btf_dedup's strs_data for strings for hash
+ * functions; later we'll just transfer hashmap to struct btf as is,
+ * along the strs_data
*/
- p = tmp_strs;
- grp_idx = 0;
- grp_used = strs.ptrs[0].used;
- /* iterate past end to avoid code duplication after loop */
- for (i = 1; i <= strs.cnt; i++) {
- /*
- * when i == strs.cnt, we want to skip string comparison and go
- * straight to handling last group of strings (otherwise we'd
- * need to handle last group after the loop w/ duplicated code)
- */
- if (i < strs.cnt &&
- !strcmp(strs.ptrs[i].str, strs.ptrs[grp_idx].str)) {
- grp_used = grp_used || strs.ptrs[i].used;
- continue;
- }
+ d->btf->strs_data_ptr = &d->strs_data;
- /*
- * this check would have been required after the loop to handle
- * last group of strings, but due to <= condition in a loop
- * we avoid that duplication
- */
- if (grp_used) {
- int new_off = p - tmp_strs;
- __u32 len = strlen(strs.ptrs[grp_idx].str);
-
- memmove(p, strs.ptrs[grp_idx].str, len + 1);
- for (j = grp_idx; j < i; j++)
- strs.ptrs[j].new_off = new_off;
- p += len + 1;
- }
-
- if (i < strs.cnt) {
- grp_idx = i;
- grp_used = strs.ptrs[i].used;
- }
+ d->strs_hash = hashmap__new(strs_hash_fn, strs_hash_equal_fn, d->btf);
+ if (IS_ERR(d->strs_hash)) {
+ err = PTR_ERR(d->strs_hash);
+ d->strs_hash = NULL;
+ goto err_out;
}
- /* replace original strings with deduped ones */
- d->btf->hdr->str_len = p - tmp_strs;
- memmove(start, tmp_strs, d->btf->hdr->str_len);
- end = start + d->btf->hdr->str_len;
-
- /* restore original order for further binary search lookups */
- qsort(strs.ptrs, strs.cnt, sizeof(strs.ptrs[0]), str_sort_by_offset);
+ /* insert empty string; we won't be looking it up during strings
+ * dedup, but it's good to have it for generic BTF string lookups
+ */
+ err = hashmap__insert(d->strs_hash, (void *)0, (void *)0,
+ HASHMAP_ADD, NULL, NULL);
+ if (err)
+ goto err_out;
/* remap string offsets */
- err = btf_for_each_str_off(d, btf_str_remap_offset, &strs);
+ err = btf_for_each_str_off(d, strs_dedup_remap_str_off, d);
if (err)
- goto done;
+ goto err_out;
- d->btf->hdr->str_len = end - start;
+ /* replace BTF string data and hash with deduped ones */
+ free(d->btf->strs_data);
+ hashmap__free(d->btf->strs_hash);
+ d->btf->strs_data = d->strs_data;
+ d->btf->strs_data_cap = d->strs_cap;
+ d->btf->hdr->str_len = d->strs_len;
+ d->btf->strs_hash = d->strs_hash;
+ /* now point strs_data_ptr back to btf->strs_data */
+ d->btf->strs_data_ptr = &d->btf->strs_data;
+
+ d->strs_data = d->strs_hash = NULL;
+ d->strs_len = d->strs_cap = 0;
d->btf->strs_deduped = true;
+ return 0;
+
+err_out:
+ free(d->strs_data);
+ hashmap__free(d->strs_hash);
+ d->strs_data = d->strs_hash = NULL;
+ d->strs_len = d->strs_cap = 0;
+
+ /* restore strings pointer for existing d->btf->strs_hash back */
+ d->btf->strs_data_ptr = &d->strs_data;
-done:
- free(tmp_strs);
- free(strs.ptrs);
return err;
}