Commit 9c6c5c48 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

libbpf: Make btf_dump work with modifiable BTF 



Ensure that btf_dump can accommodate new BTF types being appended to BTF
instance after struct btf_dump was created. This came up during attemp to
use btf_dump for raw type dumping in selftests, but given changes are not
excessive, it's good to not have any gotchas in API usage, so I decided to
support such use case in general.

Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200929232843.1249318-2-andriin@fb.com
parent ea7da1d5

tools/lib/bpf/btf.c

+17 −0
Original line number Diff line number Diff line
@@ -146,6 +146,23 @@ void *btf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz, 
	return new_data + cur_cnt * elem_sz;

}



/* Ensure given dynamically allocated memory region has enough allocated space

 * to accommodate *need_cnt* elements of size *elem_sz* bytes each

 */

int btf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt)

{

	void *p;



	if (need_cnt <= *cap_cnt)

		return 0;



	p = btf_add_mem(data, cap_cnt, elem_sz, *cap_cnt, SIZE_MAX, need_cnt - *cap_cnt);

	if (!p)

		return -ENOMEM;



	return 0;

}



static int btf_add_type_idx_entry(struct btf *btf, __u32 type_off)

{

	__u32 *p;

tools/lib/bpf/btf_dump.c

+47 −22
Original line number Diff line number Diff line
@@ -60,11 +60,14 @@ struct btf_dump { 
	struct btf_dump_opts opts;

	int ptr_sz;

	bool strip_mods;

	int last_id;



	/* per-type auxiliary state */

	struct btf_dump_type_aux_state *type_states;

	size_t type_states_cap;

	/* per-type optional cached unique name, must be freed, if present */

	const char **cached_names;

	size_t cached_names_cap;



	/* topo-sorted list of dependent type definitions */

	__u32 *emit_queue;
@@ -113,6 +116,7 @@ static void btf_dump_printf(const struct btf_dump *d, const char *fmt, ...) 
}



static int btf_dump_mark_referenced(struct btf_dump *d);

static int btf_dump_resize(struct btf_dump *d);



struct btf_dump *btf_dump__new(const struct btf *btf,

			       const struct btf_ext *btf_ext,
@@ -144,37 +148,49 @@ struct btf_dump *btf_dump__new(const struct btf *btf, 
		d->ident_names = NULL;

		goto err;

	}

	d->type_states = calloc(1 + btf__get_nr_types(d->btf),

				sizeof(d->type_states[0]));

	if (!d->type_states) {

		err = -ENOMEM;

		goto err;

	}

	d->cached_names = calloc(1 + btf__get_nr_types(d->btf),

				 sizeof(d->cached_names[0]));

	if (!d->cached_names) {

		err = -ENOMEM;



	err = btf_dump_resize(d);

	if (err)

		goto err;



	return d;

err:

	btf_dump__free(d);

	return ERR_PTR(err);

}



static int btf_dump_resize(struct btf_dump *d)

{

	int err, last_id = btf__get_nr_types(d->btf);



	if (last_id <= d->last_id)

		return 0;



	if (btf_ensure_mem((void **)&d->type_states, &d->type_states_cap,

			   sizeof(*d->type_states), last_id + 1))

		return -ENOMEM;

	if (btf_ensure_mem((void **)&d->cached_names, &d->cached_names_cap,

			   sizeof(*d->cached_names), last_id + 1))

		return -ENOMEM;



	if (d->last_id == 0) {

		/* VOID is special */

		d->type_states[0].order_state = ORDERED;

		d->type_states[0].emit_state = EMITTED;

	}



	/* eagerly determine referenced types for anon enums */

	err = btf_dump_mark_referenced(d);

	if (err)

		goto err;

		return err;



	return d;

err:

	btf_dump__free(d);

	return ERR_PTR(err);

	d->last_id = last_id;

	return 0;

}



void btf_dump__free(struct btf_dump *d)

{

	int i, cnt;

	int i;



	if (IS_ERR_OR_NULL(d))

		return;
@@ -182,7 +198,7 @@ void btf_dump__free(struct btf_dump *d) 
	free(d->type_states);

	if (d->cached_names) {

		/* any set cached name is owned by us and should be freed */

		for (i = 0, cnt = btf__get_nr_types(d->btf); i <= cnt; i++) {

		for (i = 0; i <= d->last_id; i++) {

			if (d->cached_names[i])

				free((void *)d->cached_names[i]);

		}
@@ -222,6 +238,10 @@ int btf_dump__dump_type(struct btf_dump *d, __u32 id) 
	if (id > btf__get_nr_types(d->btf))

		return -EINVAL;



	err = btf_dump_resize(d);

	if (err)

		return err;



	d->emit_queue_cnt = 0;

	err = btf_dump_order_type(d, id, false);

	if (err < 0)
@@ -251,7 +271,7 @@ static int btf_dump_mark_referenced(struct btf_dump *d) 
	const struct btf_type *t;

	__u16 vlen;



	for (i = 1; i <= n; i++) {

	for (i = d->last_id + 1; i <= n; i++) {

		t = btf__type_by_id(d->btf, i);

		vlen = btf_vlen(t);
@@ -306,6 +326,7 @@ static int btf_dump_mark_referenced(struct btf_dump *d) 
	}

	return 0;

}



static int btf_dump_add_emit_queue_id(struct btf_dump *d, __u32 id)

{

	__u32 *new_queue;
@@ -1049,11 +1070,15 @@ int btf_dump__emit_type_decl(struct btf_dump *d, __u32 id, 
			     const struct btf_dump_emit_type_decl_opts *opts)

{

	const char *fname;

	int lvl;

	int lvl, err;



	if (!OPTS_VALID(opts, btf_dump_emit_type_decl_opts))

		return -EINVAL;



	err = btf_dump_resize(d);

	if (err)

		return -EINVAL;



	fname = OPTS_GET(opts, field_name, "");

	lvl = OPTS_GET(opts, indent_level, 0);

	d->strip_mods = OPTS_GET(opts, strip_mods, false);

tools/lib/bpf/libbpf_internal.h

+1 −0
Original line number Diff line number Diff line
@@ -107,6 +107,7 @@ static inline void *libbpf_reallocarray(void *ptr, size_t nmemb, size_t size) 


void *btf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,

		  size_t cur_cnt, size_t max_cnt, size_t add_cnt);

int btf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt);



static inline bool libbpf_validate_opts(const char *opts,

					size_t opts_sz, size_t user_sz,