btf_loader issues a warning when it sees several BTF_DECL_TAGs
pointing to the same type. Such situation is possible in practice
after patch [0], that marks certain functions with kfunc and
bpf_fastcall tags. E.g.:
$ pfunct vmlinux -F btf -f bpf_rdonly_cast
WARNING: still unsuported BTF_KIND_DECL_TAG(bpf_fastcall) for bpf_cast_to_kern_ctx already with attribute (bpf_kfunc), ignoring
WARNING: still unsuported BTF_KIND_DECL_TAG(bpf_fastcall) for bpf_rdonly_cast already with attribute (bpf_kfunc), ignoring
bpf_kfunc void * bpf_rdonly_cast(const void * obj__ign, u32 btf_id__k);
This commit extends 'struct tag' to allow attaching multiple
attributes. Define 'struct attributes' as follows:
struct attributes {
uint64_t cnt;
const char *values[];
};
In order to avoid adding counter field in 'struct tag',
as not many instances of 'struct tag' would have attributes.
Same command after this patch:
$ pfunct vmlinux -F btf -f bpf_rdonly_cast
bpf_kfunc bpf_fastcall void * bpf_rdonly_cast(const void * obj__ign, u32 btf_id__k);
[0] https://lore.kernel.org/dwarves/094b626d44e817240ae8e44b6f7933b13c26d879.camel@xxxxxxxxx/T/#m8a6cb49a99d1b2ba38d616495a540ae8fc5f3a76
Reported-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Closes: https://lore.kernel.org/dwarves/Z1dFXVFYmQ-nHSVO@x1/
Signed-off-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
---
btf_loader.c | 31 +++++++++++++++++++++++--------
dwarf_loader.c | 2 +-
dwarves.c | 3 +++
dwarves.h | 8 +++++++-
dwarves_fprintf.c | 6 ++++--
tests/btf_functions.sh | 2 +-
6 files changed, 39 insertions(+), 13 deletions(-)
diff --git a/btf_loader.c b/btf_loader.c
index 4814f29..af9e1db 100644
--- a/btf_loader.c
+++ b/btf_loader.c
@@ -459,9 +459,28 @@ static int create_new_tag(struct cu *cu, int type, const struct btf_type *tp, ui
return 0;
}
+static struct attributes *attributes__realloc(struct attributes *attributes, const char *value)
+{
+ struct attributes *result;
+ uint64_t cnt;
+ size_t sz;
+
+ cnt = attributes ? attributes->cnt : 0;
+ sz = sizeof(*attributes) + (cnt + 1) * sizeof(*attributes->values);
+ result = realloc(attributes, sz);
+ if (!result)
+ return NULL;
+ if (!attributes)
+ result->cnt = 0;
+ result->values[cnt] = value;
+ result->cnt++;
+ return result;
+}
+
static int process_decl_tag(struct cu *cu, const struct btf_type *tp)
{
struct tag *tag = cu__type(cu, tp->type);
+ struct attributes *tmp;
if (tag == NULL)
tag = cu__function(cu, tp->type);
@@ -475,15 +494,11 @@ static int process_decl_tag(struct cu *cu, const struct btf_type *tp)
}
const char *attribute = cu__btf_str(cu, tp->name_off);
+ tmp = attributes__realloc(tag->attributes, attribute);
+ if (!tmp)
+ return -ENOMEM;
- if (tag->attribute != NULL) {
- char bf[128];
-
- fprintf(stderr, "WARNING: still unsuported BTF_KIND_DECL_TAG(%s) for %s already with attribute (%s), ignoring\n",
- attribute, tag__name(tag, cu, bf, sizeof(bf), NULL), tag->attribute);
- } else {
- tag->attribute = attribute;
- }
+ tag->attributes = tmp;
return 0;
}
diff --git a/dwarf_loader.c b/dwarf_loader.c
index 598fde4..34376b2 100644
--- a/dwarf_loader.c
+++ b/dwarf_loader.c
@@ -513,7 +513,7 @@ static void tag__init(struct tag *tag, struct cu *cu, Dwarf_Die *die)
dwarf_tag__set_attr_type(dtag, abstract_origin, die, DW_AT_abstract_origin);
tag->recursivity_level = 0;
- tag->attribute = NULL;
+ tag->attributes = NULL;
if (cu->extra_dbg_info) {
pthread_mutex_lock(&libdw__lock);
diff --git a/dwarves.c b/dwarves.c
index ae512b9..f970dd2 100644
--- a/dwarves.c
+++ b/dwarves.c
@@ -210,6 +210,9 @@ void tag__delete(struct tag *tag, struct cu *cu)
assert(list_empty(&tag->node));
+ if (tag->attributes)
+ free(tag->attributes);
+
switch (tag->tag) {
case DW_TAG_union_type:
type__delete(tag__type(tag), cu); break;
diff --git a/dwarves.h b/dwarves.h
index 1cb0d62..0a4d5a2 100644
--- a/dwarves.h
+++ b/dwarves.h
@@ -516,10 +516,16 @@ int cu__for_all_tags(struct cu *cu,
struct cu *cu, void *cookie),
void *cookie);
+struct attributes {
+ uint64_t cnt;
+ const char *values[];
+};
+
/** struct tag - basic representation of a debug info element
* @priv - extra data, for instance, DWARF offset, id, decl_{file,line}
* @top_level -
* @shared_tags: used by struct namespace
+ * @attributes - attributes specified by BTF_DECL_TAGs targeting this tag
*/
struct tag {
struct list_head node;
@@ -530,7 +536,7 @@ struct tag {
bool has_btf_type_tag:1;
bool shared_tags:1;
uint8_t recursivity_level;
- const char *attribute;
+ struct attributes *attributes;
};
// To use with things like type->type_enum == perf_event_type+perf_user_event_type
diff --git a/dwarves_fprintf.c b/dwarves_fprintf.c
index e16a6b4..c3e7f3c 100644
--- a/dwarves_fprintf.c
+++ b/dwarves_fprintf.c
@@ -1405,9 +1405,11 @@ static size_t function__fprintf(const struct tag *tag, const struct cu *cu,
struct ftype *ftype = func->btf ? tag__ftype(cu__type(cu, func->proto.tag.type)) : &func->proto;
size_t printed = 0;
bool inlined = !conf->strip_inline && function__declared_inline(func);
+ int i;
- if (tag->attribute)
- printed += fprintf(fp, "%s ", tag->attribute);
+ if (tag->attributes)
+ for (i = 0; i < tag->attributes->cnt; ++i)
+ printed += fprintf(fp, "%s ", tag->attributes->values[i]);
if (func->virtuality == DW_VIRTUALITY_virtual ||
func->virtuality == DW_VIRTUALITY_pure_virtual)
diff --git a/tests/btf_functions.sh b/tests/btf_functions.sh
index 61f8a00..c92e5ae 100755
--- a/tests/btf_functions.sh
+++ b/tests/btf_functions.sh
@@ -66,7 +66,7 @@ pfunct --all --no_parm_names --format_path=dwarf $vmlinux | \
sort|uniq > $outdir/dwarf.funcs
# all functions from BTF (removing bpf_kfunc prefix where found)
pfunct --all --no_parm_names --format_path=btf $outdir/vmlinux.btf 2>/dev/null|\
- awk '{ gsub("^bpf_kfunc ",""); print $0}'|sort|uniq > $outdir/btf.funcs
+ awk '{ gsub("^(bpf_kfunc |bpf_fastcall )+",""); print $0}'|sort|uniq > $outdir/btf.funcs
exact=0
inline=0
--
2.47.0
