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Message-ID: <20200929232843.1249318-2-andriin@fb.com>
Date: Tue, 29 Sep 2020 16:28:40 -0700
From: Andrii Nakryiko <andriin@...com>
To: <bpf@...r.kernel.org>, <netdev@...r.kernel.org>, <ast@...com>,
<daniel@...earbox.net>
CC: <andrii.nakryiko@...il.com>, <kernel-team@...com>,
Andrii Nakryiko <andriin@...com>
Subject: [PATCH bpf-next 1/4] 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: Andrii Nakryiko <andriin@...com>
---
tools/lib/bpf/btf.c | 17 ++++++++
tools/lib/bpf/btf_dump.c | 69 ++++++++++++++++++++++-----------
tools/lib/bpf/libbpf_internal.h | 1 +
3 files changed, 65 insertions(+), 22 deletions(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index e1dbd766c698..df4fd9132079 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -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;
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index 91310e528a3a..2f9d685bd522 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -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 @@ struct btf_dump *btf_dump__new(const struct btf *btf,
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);
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index eed5b624a784..d99bc847bf84 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -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,
--
2.24.1
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