Commit 92b57121 authored by Okash Khawaja's avatar Okash Khawaja Committed by Daniel Borkmann
Browse files

bpf: btf: export btf types and name by offset from lib 



This patch introduces btf__resolve_type() function and exports two
existing functions from libbpf. btf__resolve_type follows modifier
types like const and typedef until it hits a type which actually takes
up memory, and then returns it. This function follows similar pattern
to btf__resolve_size but instead of computing size, it just returns
the type.

These  functions will be used in the followig patch which parses
information inside array of `struct btf_type *`. btf_name_by_offset is
used for printing variable names.

Signed-off-by: default avatarOkash Khawaja <osk@fb.com>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Reviewed-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent db42a21a

tools/lib/bpf/btf.c

+45 −20
Original line number Original line Diff line number Diff line
@@ -17,6 +17,11 @@ 




#define BTF_MAX_NR_TYPES 65535

#define BTF_MAX_NR_TYPES 65535





#define IS_MODIFIER(k) (((k) == BTF_KIND_TYPEDEF) || \

		((k) == BTF_KIND_VOLATILE) || \

		((k) == BTF_KIND_CONST) || \

		((k) == BTF_KIND_RESTRICT))



static struct btf_type btf_void;

static struct btf_type btf_void;





struct btf {

struct btf {
@@ -33,14 +38,6 @@ struct btf { 
	int fd;

	int fd;

};

};





static const char *btf_name_by_offset(const struct btf *btf, uint32_t offset)

{

	if (offset < btf->hdr->str_len)

		return &btf->strings[offset];

	else

		return NULL;

}



static int btf_add_type(struct btf *btf, struct btf_type *t)

static int btf_add_type(struct btf *btf, struct btf_type *t)

{

{

	if (btf->types_size - btf->nr_types < 2) {

	if (btf->types_size - btf->nr_types < 2) {
@@ -190,15 +187,6 @@ static int btf_parse_type_sec(struct btf *btf, btf_print_fn_t err_log) 
	return 0;

	return 0;

}

}





static const struct btf_type *btf_type_by_id(const struct btf *btf,

					     uint32_t type_id)

{

	if (type_id > btf->nr_types)

		return NULL;



	return btf->types[type_id];

}



static bool btf_type_is_void(const struct btf_type *t)

static bool btf_type_is_void(const struct btf_type *t)

{

{

	return t == &btf_void || BTF_INFO_KIND(t->info) == BTF_KIND_FWD;

	return t == &btf_void || BTF_INFO_KIND(t->info) == BTF_KIND_FWD;
@@ -234,7 +222,7 @@ int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id) 
	int64_t size = -1;

	int64_t size = -1;

	int i;

	int i;





	t = btf_type_by_id(btf, type_id);

	t = btf__type_by_id(btf, type_id);

	for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t);

	for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t);

	     i++) {

	     i++) {

		size = btf_type_size(t);

		size = btf_type_size(t);
@@ -259,7 +247,7 @@ int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id) 
			return -EINVAL;

			return -EINVAL;

		}

		}





		t = btf_type_by_id(btf, type_id);

		t = btf__type_by_id(btf, type_id);

	}

	}





	if (size < 0)

	if (size < 0)
@@ -271,6 +259,26 @@ int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id) 
	return nelems * size;

	return nelems * size;

}

}





int btf__resolve_type(const struct btf *btf, __u32 type_id)

{

	const struct btf_type *t;

	int depth = 0;



	t = btf__type_by_id(btf, type_id);

	while (depth < MAX_RESOLVE_DEPTH &&

	       !btf_type_is_void_or_null(t) &&

	       IS_MODIFIER(BTF_INFO_KIND(t->info))) {

		type_id = t->type;

		t = btf__type_by_id(btf, type_id);

		depth++;

	}



	if (depth == MAX_RESOLVE_DEPTH || btf_type_is_void_or_null(t))

		return -EINVAL;



	return type_id;

}



int32_t btf__find_by_name(const struct btf *btf, const char *type_name)

int32_t btf__find_by_name(const struct btf *btf, const char *type_name)

{

{

	uint32_t i;

	uint32_t i;
@@ -280,7 +288,7 @@ int32_t btf__find_by_name(const struct btf *btf, const char *type_name) 




	for (i = 1; i <= btf->nr_types; i++) {

	for (i = 1; i <= btf->nr_types; i++) {

		const struct btf_type *t = btf->types[i];

		const struct btf_type *t = btf->types[i];

		const char *name = btf_name_by_offset(btf, t->name_off);

		const char *name = btf__name_by_offset(btf, t->name_off);





		if (name && !strcmp(type_name, name))

		if (name && !strcmp(type_name, name))

			return i;

			return i;
@@ -371,3 +379,20 @@ int btf__fd(const struct btf *btf) 
{

{

	return btf->fd;

	return btf->fd;

}

}



const char *btf__name_by_offset(const struct btf *btf, __u32 offset)

{

	if (offset < btf->hdr->str_len)

		return &btf->strings[offset];

	else

		return NULL;

}



const struct btf_type *btf__type_by_id(const struct btf *btf,

				       __u32 type_id)

{

	if (type_id > btf->nr_types)

		return NULL;



	return btf->types[type_id];

}

tools/lib/bpf/btf.h

+3 −0
Original line number Original line Diff line number Diff line
@@ -17,6 +17,9 @@ void btf__free(struct btf *btf); 
struct btf *btf__new(uint8_t *data, uint32_t size, btf_print_fn_t err_log);

struct btf *btf__new(uint8_t *data, uint32_t size, btf_print_fn_t err_log);

int32_t btf__find_by_name(const struct btf *btf, const char *type_name);

int32_t btf__find_by_name(const struct btf *btf, const char *type_name);

int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id);

int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id);

int btf__resolve_type(const struct btf *btf, __u32 type_id);

int btf__fd(const struct btf *btf);

int btf__fd(const struct btf *btf);

const char *btf__name_by_offset(const struct btf *btf, __u32 offset);

const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id);





#endif
 
#endif

CRA Git | Maintained and supported by SUSTech CRA and CCSE