Re: [PATCH bpf-next 2/6] libbpf: Add BTF_KIND_FLOAT support

The logic follows that of BTF_KIND_INT most of the time. Sanitization
replaces BTF_KIND_FLOATs with equally-sized BTF_KIND_INTs on older
kernels.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
  tools/lib/bpf/btf.c             | 44 +++++++++++++++++++++++++++++++++
  tools/lib/bpf/btf.h             |  8 ++++++
  tools/lib/bpf/btf_dump.c        |  4 +++
  tools/lib/bpf/libbpf.c          | 29 +++++++++++++++++++++-
  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 d9c10830d749..07a30e98c3de 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c

@@ -291,6 +291,7 @@ 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);

@@ -338,6 +339,7 @@ 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));

@@ -578,6 +580,7 @@ __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:

@@ -621,6 +624,7 @@ 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);

@@ -2373,6 +2377,42 @@ int btf__add_datasec(struct btf *btf, const char *name, __u32 byte_sz)
  	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;