The logic follows that of BTF_KIND_INT most of the time. Sanitization
replaces BTF_KIND_FLOATs with equally-sized empty BTF_KIND_STRUCTs on
older kernels, for example, the following:
[4] FLOAT 'float' size=4
becomes the following:
[4] STRUCT '(anon)' size=4 vlen=0
Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
tools/lib/bpf/btf.c | 49 +++++++++++++++++++++++++++++++++
tools/lib/bpf/btf.h | 6 ++++
tools/lib/bpf/btf_dump.c | 4 +++
tools/lib/bpf/libbpf.c | 26 ++++++++++++++++-
tools/lib/bpf/libbpf.map | 5 ++++
tools/lib/bpf/libbpf_internal.h | 2 ++
6 files changed, 91 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 313f62a78626..488464307c0f 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -292,6 +292,7 @@ static int btf_type_size(const struct btf_type *t)
case BTF_KIND_PTR:
case BTF_KIND_TYPEDEF:
case BTF_KIND_FUNC:
+ case BTF_KIND_FLOAT:
return base_size;
case BTF_KIND_INT:
return base_size + sizeof(__u32);
@@ -339,6 +340,7 @@ static int btf_bswap_type_rest(struct btf_type *t)
case BTF_KIND_PTR:
case BTF_KIND_TYPEDEF:
case BTF_KIND_FUNC:
+ case BTF_KIND_FLOAT:
return 0;
case BTF_KIND_INT:
*(__u32 *)(t + 1) = bswap_32(*(__u32 *)(t + 1));
@@ -579,6 +581,7 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
case BTF_KIND_UNION:
case BTF_KIND_ENUM:
case BTF_KIND_DATASEC:
+ case BTF_KIND_FLOAT:
size = t->size;
goto done;
case BTF_KIND_PTR:
@@ -622,6 +625,7 @@ int btf__align_of(const struct btf *btf, __u32 id)
switch (kind) {
case BTF_KIND_INT:
case BTF_KIND_ENUM:
+ case BTF_KIND_FLOAT:
return min(btf_ptr_sz(btf), (size_t)t->size);
case BTF_KIND_PTR:
return btf_ptr_sz(btf);
@@ -1783,6 +1787,47 @@ int btf__add_int(struct btf *btf, const char *name, size_t byte_sz, int encoding
return btf_commit_type(btf, sz);
}
+/*
+ * Append new BTF_KIND_FLOAT type with:
+ * - *name* - non-empty, non-NULL type name;
+ * - *sz* - size of the type, in bytes;
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_float(struct btf *btf, const char *name, size_t byte_sz)
+{
+ struct btf_type *t;
+ int sz, name_off;
+
+ /* non-empty name */
+ if (!name || !name[0])
+ return -EINVAL;
+
+ /* byte_sz must be one of the explicitly allowed values */
+ if (byte_sz != 2 && byte_sz != 4 && byte_sz != 8 && byte_sz != 12 &&
+ byte_sz != 16)
+ return -EINVAL;
+
+ if (btf_ensure_modifiable(btf))
+ return -ENOMEM;
+
+ sz = sizeof(struct btf_type);
+ t = btf_add_type_mem(btf, sz);
+ if (!t)
+ return -ENOMEM;
+
+ name_off = btf__add_str(btf, name);
+ if (name_off < 0)
+ return name_off;
+
+ t->name_off = name_off;
+ t->info = btf_type_info(BTF_KIND_FLOAT, 0, 0);
+ t->size = byte_sz;
+
+ return btf_commit_type(btf, sz);
+}
+
/* it's completely legal to append BTF types with type IDs pointing forward to
* types that haven't been appended yet, so we only make sure that id looks
* sane, we can't guarantee that ID will always be valid
@@ -3653,6 +3698,7 @@ static int btf_dedup_prep(struct btf_dedup *d)
case BTF_KIND_FWD:
case BTF_KIND_TYPEDEF:
case BTF_KIND_FUNC:
+ case BTF_KIND_FLOAT:
h = btf_hash_common(t);
break;
case BTF_KIND_INT:
@@ -3749,6 +3795,7 @@ static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
break;
case BTF_KIND_FWD:
+ case BTF_KIND_FLOAT:
h = btf_hash_common(t);
for_each_dedup_cand(d, hash_entry, h) {
cand_id = (__u32)(long)hash_entry->value;
@@ -4010,6 +4057,7 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
return btf_compat_enum(cand_type, canon_type);
case BTF_KIND_FWD:
+ case BTF_KIND_FLOAT:
return btf_equal_common(cand_type, canon_type);
case BTF_KIND_CONST:
@@ -4506,6 +4554,7 @@ static int btf_dedup_remap_type(struct btf_dedup *d, __u32 type_id)
switch (btf_kind(t)) {
case BTF_KIND_INT:
case BTF_KIND_ENUM:
+ case BTF_KIND_FLOAT:
break;
case BTF_KIND_FWD:
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 1237bcd1dd17..029a9cfc8c2d 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -95,6 +95,7 @@ LIBBPF_API int btf__find_str(struct btf *btf, const char *s);
LIBBPF_API int btf__add_str(struct btf *btf, const char *s);
LIBBPF_API int btf__add_int(struct btf *btf, const char *name, size_t byte_sz, int encoding);
+LIBBPF_API int btf__add_float(struct btf *btf, const char *name, size_t byte_sz);
LIBBPF_API int btf__add_ptr(struct btf *btf, int ref_type_id);
LIBBPF_API int btf__add_array(struct btf *btf,
int index_type_id, int elem_type_id, __u32 nr_elems);
@@ -294,6 +295,11 @@ static inline bool btf_is_datasec(const struct btf_type *t)
return btf_kind(t) == BTF_KIND_DATASEC;
}
+static inline bool btf_is_float(const struct btf_type *t)
+{
+ return btf_kind(t) == BTF_KIND_FLOAT;
+}
+
static inline __u8 btf_int_encoding(const struct btf_type *t)
{
return BTF_INT_ENCODING(*(__u32 *)(t + 1));
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index 2f9d685bd522..5e957fcceee6 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -279,6 +279,7 @@ static int btf_dump_mark_referenced(struct btf_dump *d)
case BTF_KIND_INT:
case BTF_KIND_ENUM:
case BTF_KIND_FWD:
+ case BTF_KIND_FLOAT:
break;
case BTF_KIND_VOLATILE:
@@ -453,6 +454,7 @@ static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr)
switch (btf_kind(t)) {
case BTF_KIND_INT:
+ case BTF_KIND_FLOAT:
tstate->order_state = ORDERED;
return 0;
@@ -1133,6 +1135,7 @@ static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
case BTF_KIND_TYPEDEF:
+ case BTF_KIND_FLOAT:
goto done;
default:
pr_warn("unexpected type in decl chain, kind:%u, id:[%u]\n",
@@ -1247,6 +1250,7 @@ static void btf_dump_emit_type_chain(struct btf_dump *d,
switch (kind) {
case BTF_KIND_INT:
+ case BTF_KIND_FLOAT:
btf_dump_emit_mods(d, decls);
name = btf_name_of(d, t->name_off);
btf_dump_printf(d, "%s", name);
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index d43cc3f29dae..d3ccd2aec6d2 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -178,6 +178,8 @@ enum kern_feature_id {
FEAT_PROG_BIND_MAP,
/* Kernel support for module BTFs */
FEAT_MODULE_BTF,
+ /* BTF_KIND_FLOAT support */
+ FEAT_BTF_FLOAT,
__FEAT_CNT,
};
@@ -1935,6 +1937,7 @@ static const char *btf_kind_str(const struct btf_type *t)
case BTF_KIND_FUNC_PROTO: return "func_proto";
case BTF_KIND_VAR: return "var";
case BTF_KIND_DATASEC: return "datasec";
+ case BTF_KIND_FLOAT: return "float";
default: return "unknown";
}
}
@@ -2384,15 +2387,17 @@ static bool btf_needs_sanitization(struct bpf_object *obj)
{
bool has_func_global = kernel_supports(FEAT_BTF_GLOBAL_FUNC);
bool has_datasec = kernel_supports(FEAT_BTF_DATASEC);
+ bool has_float = kernel_supports(FEAT_BTF_FLOAT);
bool has_func = kernel_supports(FEAT_BTF_FUNC);
- return !has_func || !has_datasec || !has_func_global;
+ return !has_func || !has_datasec || !has_func_global || !has_float;
}
static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
{
bool has_func_global = kernel_supports(FEAT_BTF_GLOBAL_FUNC);
bool has_datasec = kernel_supports(FEAT_BTF_DATASEC);
+ bool has_float = kernel_supports(FEAT_BTF_FLOAT);
bool has_func = kernel_supports(FEAT_BTF_FUNC);
struct btf_type *t;
int i, j, vlen;
@@ -2445,6 +2450,10 @@ static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
} else if (!has_func_global && btf_is_func(t)) {
/* replace BTF_FUNC_GLOBAL with BTF_FUNC_STATIC */
t->info = BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0);
+ } else if (!has_float && btf_is_float(t)) {
+ /* replace FLOAT with an equally-sized empty STRUCT */
+ t->name_off = 0;
+ t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 0);
}
}
}
@@ -3882,6 +3891,18 @@ static int probe_kern_btf_datasec(void)
strs, sizeof(strs)));
}
+static int probe_kern_btf_float(void)
+{
+ static const char strs[] = "\0float";
+ __u32 types[] = {
+ /* float */
+ BTF_TYPE_FLOAT_ENC(1, 4),
+ };
+
+ return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+ strs, sizeof(strs)));
+}
+
static int probe_kern_array_mmap(void)
{
struct bpf_create_map_attr attr = {
@@ -4061,6 +4082,9 @@ static struct kern_feature_desc {
[FEAT_MODULE_BTF] = {
"module BTF support", probe_module_btf,
},
+ [FEAT_BTF_FLOAT] = {
+ "BTF_KIND_FLOAT support", probe_kern_btf_float,
+ },
};
static bool kernel_supports(enum kern_feature_id feat_id)
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 1c0fd2dd233a..ec898f464ab9 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -350,3 +350,8 @@ LIBBPF_0.3.0 {
xsk_setup_xdp_prog;
xsk_socket__update_xskmap;
} LIBBPF_0.2.0;
+
+LIBBPF_0.4.0 {
+ global:
+ btf__add_float;
+} LIBBPF_0.3.0;
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 969d0ac592ba..343f6eb05637 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -31,6 +31,8 @@
#define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset)
#define BTF_PARAM_ENC(name, type) (name), (type)
#define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size)
+#define BTF_TYPE_FLOAT_ENC(name, sz) \
+ BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_FLOAT, 0, 0), sz)
#ifndef likely
#define likely(x) __builtin_expect(!!(x), 1)
--
2.29.2
