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libbpf: Make btf_dump work with modifiable BTF

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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: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200929232843.1249318-2-andriin@fb.com
This commit is contained in:
Andrii Nakryiko
2020-09-29 16:28:40 -07:00
committed by Andrii Nakryiko
parent 80c7838600
commit 317ef1c295
3 changed files with 65 additions and 22 deletions
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69
src/btf_dump.c
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@@ -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,
@@ -144,25 +148,8 @@ 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;
goto err;
}
/* 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);
err = btf_dump_resize(d);
if (err)
goto err;
@@ -172,9 +159,38 @@ err:
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)
return 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);