tools/libbpf: support bigger BTF data sizes

While it's understandable why kernel limits number of BTF types to 65535
and size of string section to 64KB, in libbpf as user-space library it's
too restrictive. E.g., pahole converting DWARF to BTF type information
for Linux kernel generates more than 3 million BTF types and more than
3MB of strings, before deduplication. So to allow btf__dedup() to do its
work, we need to be able to load bigger BTF sections using btf__new().

Singed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 8 insertions, 7 deletions

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index ade1c32fb083..68b50e9bbde1 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -16,7 +16,8 @@
 #define max(a, b) ((a) > (b) ? (a) : (b))
 #define min(a, b) ((a) < (b) ? (a) : (b))
 
-#define BTF_MAX_NR_TYPES 65535
+#define BTF_MAX_NR_TYPES 0x7fffffff
+#define BTF_MAX_STR_OFFSET 0x7fffffff
 
 #define IS_MODIFIER(k) (((k) == BTF_KIND_TYPEDEF) || \
                 ((k) == BTF_KIND_VOLATILE) || \
@@ -175,7 +176,7 @@ static int btf_parse_str_sec(struct btf *btf)
         const char *start = btf->nohdr_data + hdr->str_off;
         const char *end = start + btf->hdr->str_len;
 
-        if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_NAME_OFFSET ||
+        if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_STR_OFFSET ||
             start[0] || end[-1]) {
                 pr_debug("Invalid BTF string section\n");
                 return -EINVAL;
@@ -1882,7 +1883,7 @@ static int btf_dedup_prim_types(struct btf_dedup *d)
  */
 static inline bool is_type_mapped(struct btf_dedup *d, uint32_t type_id)
 {
-        return d->map[type_id] <= BTF_MAX_TYPE;
+        return d->map[type_id] <= BTF_MAX_NR_TYPES;
 }
 
 /*
@@ -2033,7 +2034,7 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
         canon_id = resolve_fwd_id(d, canon_id);
 
         hypot_type_id = d->hypot_map[canon_id];
-        if (hypot_type_id <= BTF_MAX_TYPE)
+        if (hypot_type_id <= BTF_MAX_NR_TYPES)
                 return hypot_type_id == cand_id;
 
         if (btf_dedup_hypot_map_add(d, canon_id, cand_id))
@@ -2252,7 +2253,7 @@ static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id)
         __u32 h;
 
         /* already deduped or is in process of deduping (loop detected) */
-        if (d->map[type_id] <= BTF_MAX_TYPE)
+        if (d->map[type_id] <= BTF_MAX_NR_TYPES)
                 return 0;
 
         t = d->btf->types[type_id];
@@ -2329,7 +2330,7 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
 
         if (d->map[type_id] == BTF_IN_PROGRESS_ID)
                 return -ELOOP;
-        if (d->map[type_id] <= BTF_MAX_TYPE)
+        if (d->map[type_id] <= BTF_MAX_NR_TYPES)
                 return resolve_type_id(d, type_id);
 
         t = d->btf->types[type_id];
@@ -2509,7 +2510,7 @@ static int btf_dedup_remap_type_id(struct btf_dedup *d, __u32 type_id)
 
         resolved_type_id = resolve_type_id(d, type_id);
         new_type_id = d->hypot_map[resolved_type_id];
-        if (new_type_id > BTF_MAX_TYPE)
+        if (new_type_id > BTF_MAX_NR_TYPES)
                 return -EINVAL;
         return new_type_id;
 }