Expose useful function emitting field/variable declaration compilable C syntax
of a provided BTF type. This is going to be used by bpftool when emitting data
section layout as a struct. This is not a trivial algorithm, so better to
expose it as internal API and let bpftool harness existing libbpf code. As
part of making this API useful in a stand-alone fashion, move initialization
of some of the internal btf_dumper state to early phase.
Also expose useful btf_align_of() function returning alignment of a given BTF
type. This is also used for data section layout-compatible struct definition,
specifically to determine necessary extra padding between fields/variables.
Acked-by: Martin KaFai Lau <kafai@xxxxxx>
Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
---
tools/lib/bpf/btf_dump.c | 61 ++++++++++++++++-----------------
tools/lib/bpf/libbpf_internal.h | 6 ++++
2 files changed, 36 insertions(+), 31 deletions(-)
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index cb126d8fcf75..e597eb9541f5 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -116,6 +116,8 @@ static void btf_dump_printf(const struct btf_dump *d, const char *fmt, ...)
va_end(args);
}
+static int btf_dump_mark_referenced(struct btf_dump *d);
+
struct btf_dump *btf_dump__new(const struct btf *btf,
const struct btf_ext *btf_ext,
const struct btf_dump_opts *opts,
@@ -137,18 +139,39 @@ struct btf_dump *btf_dump__new(const struct btf *btf,
if (IS_ERR(d->type_names)) {
err = PTR_ERR(d->type_names);
d->type_names = NULL;
- btf_dump__free(d);
- return ERR_PTR(err);
}
d->ident_names = hashmap__new(str_hash_fn, str_equal_fn, NULL);
if (IS_ERR(d->ident_names)) {
err = PTR_ERR(d->ident_names);
d->ident_names = NULL;
- btf_dump__free(d);
- return ERR_PTR(err);
+ 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);
+ if (err)
+ goto err;
+
return d;
+err:
+ btf_dump__free(d);
+ return ERR_PTR(err);
}
void btf_dump__free(struct btf_dump *d)
@@ -175,7 +198,6 @@ void btf_dump__free(struct btf_dump *d)
free(d);
}
-static int btf_dump_mark_referenced(struct btf_dump *d);
static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr);
static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id);
@@ -202,27 +224,6 @@ int btf_dump__dump_type(struct btf_dump *d, __u32 id)
if (id > btf__get_nr_types(d->btf))
return -EINVAL;
- /* type states are lazily allocated, as they might not be needed */
- if (!d->type_states) {
- d->type_states = calloc(1 + btf__get_nr_types(d->btf),
- sizeof(d->type_states[0]));
- if (!d->type_states)
- return -ENOMEM;
- d->cached_names = calloc(1 + btf__get_nr_types(d->btf),
- sizeof(d->cached_names[0]));
- if (!d->cached_names)
- return -ENOMEM;
-
- /* 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->emit_queue_cnt = 0;
err = btf_dump_order_type(d, id, false);
if (err < 0)
@@ -565,8 +566,6 @@ struct id_stack {
int cnt;
};
-static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
- const char *fname, int lvl);
static void btf_dump_emit_type_chain(struct btf_dump *d,
struct id_stack *decl_stack,
const char *fname, int lvl);
@@ -752,7 +751,7 @@ static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id)
}
}
-static int btf_align_of(const struct btf *btf, __u32 id)
+int btf_align_of(const struct btf *btf, __u32 id)
{
const struct btf_type *t = btf__type_by_id(btf, id);
__u16 kind = btf_kind(t);
@@ -1051,8 +1050,8 @@ static int btf_dump_push_decl_stack_id(struct btf_dump *d, __u32 id)
* of a stack frame. Some care is required to "pop" stack frames after
* processing type declaration chain.
*/
-static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
- const char *fname, int lvl)
+void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
+ const char *fname, int lvl)
{
struct id_stack decl_stack;
const struct btf_type *t;
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 7ee0c8691835..bb7fd22eb0ab 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -98,6 +98,12 @@ static inline bool libbpf_validate_opts(const char *opts,
int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
const char *str_sec, size_t str_len);
+struct btf_dump;
+
+void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id, const char *fname,
+ int lvl);
+int btf_align_of(const struct btf *btf, __u32 id);
+
int bpf_object__section_size(const struct bpf_object *obj, const char *name,
__u32 *size);
int bpf_object__variable_offset(const struct bpf_object *obj, const char *name,
--
2.17.1
