diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c
index 01b56939a835b77f71b419c9431d3eb9322d07da..b4fff912dce24d42af3bcf16e53f090ef5f2ed12 100644
--- a/tools/lib/bpf/linker.c
+++ b/tools/lib/bpf/linker.c
@@ -32,12 +32,17 @@ struct src_sec {
int dst_off;
/* whether section is omitted from the final ELF file */
bool skipped;
+ /* whether section is an ephemeral section, not mapped to an ELF section */
+ bool ephemeral;
/* ELF info */
size_t sec_idx;
Elf_Scn *scn;
Elf64_Shdr *shdr;
Elf_Data *data;
+
+ /* corresponding BTF DATASEC type ID */
+ int sec_type_id;
};
struct src_obj {
@@ -49,12 +54,24 @@ struct src_obj {
/* SYMTAB section index */
size_t symtab_sec_idx;
- /* List of sections. Slot zero is unused. */
+ struct btf *btf;
+ struct btf_ext *btf_ext;
+
+ /* List of sections (including ephemeral). Slot zero is unused. */
struct src_sec *secs;
int sec_cnt;
/* mapping of symbol indices from src to dst ELF */
int *sym_map;
+ /* mapping from the src BTF type IDs to dst ones */
+ int *btf_type_map;
+};
+
+/* single .BTF.ext data section */
+struct btf_ext_sec_data {
+ size_t rec_cnt;
+ __u32 rec_sz;
+ void *recs;
};
struct dst_sec {
@@ -75,6 +92,15 @@ struct dst_sec {
/* corresponding STT_SECTION symbol index in SYMTAB */
int sec_sym_idx;
+
+ /* section's DATASEC variable info, emitted on BTF finalization */
+ int sec_var_cnt;
+ struct btf_var_secinfo *sec_vars;
+
+ /* section's .BTF.ext data */
+ struct btf_ext_sec_data func_info;
+ struct btf_ext_sec_data line_info;
+ struct btf_ext_sec_data core_relo_info;
};
struct bpf_linker {
@@ -90,6 +116,9 @@ struct bpf_linker {
struct strset *strtab_strs; /* STRTAB unique strings */
size_t strtab_sec_idx; /* STRTAB section index */
size_t symtab_sec_idx; /* SYMTAB section index */
+
+ struct btf *btf;
+ struct btf_ext *btf_ext;
};
#define pr_warn_elf(fmt, ...) \
@@ -101,9 +130,17 @@ static int init_output_elf(struct bpf_linker *linker, const char *file);
static int linker_load_obj_file(struct bpf_linker *linker, const char *filename, struct src_obj *obj);
static int linker_sanity_check_elf(struct src_obj *obj);
+static int linker_sanity_check_btf(struct src_obj *obj);
+static int linker_sanity_check_btf_ext(struct src_obj *obj);
+static int linker_fixup_btf(struct src_obj *obj);
static int linker_append_sec_data(struct bpf_linker *linker, struct src_obj *obj);
static int linker_append_elf_syms(struct bpf_linker *linker, struct src_obj *obj);
static int linker_append_elf_relos(struct bpf_linker *linker, struct src_obj *obj);
+static int linker_append_btf(struct bpf_linker *linker, struct src_obj *obj);
+static int linker_append_btf_ext(struct bpf_linker *linker, struct src_obj *obj);
+
+static int finalize_btf(struct bpf_linker *linker);
+static int finalize_btf_ext(struct bpf_linker *linker);
void bpf_linker__free(struct bpf_linker *linker)
{
@@ -122,11 +159,19 @@ void bpf_linker__free(struct bpf_linker *linker)
strset__free(linker->strtab_strs);
+ btf__free(linker->btf);
+ btf_ext__free(linker->btf_ext);
+
for (i = 1; i < linker->sec_cnt; i++) {
struct dst_sec *sec = &linker->secs[i];
free(sec->sec_name);
free(sec->raw_data);
+ free(sec->sec_vars);
+
+ free(sec->func_info.recs);
+ free(sec->line_info.recs);
+ free(sec->core_relo_info.recs);
}
free(linker->secs);
@@ -335,6 +380,12 @@ static int init_output_elf(struct bpf_linker *linker, const char *file)
sec->shdr->sh_addralign = 8;
sec->shdr->sh_entsize = sizeof(Elf64_Sym);
+ /* .BTF */
+ linker->btf = btf__new_empty();
+ err = libbpf_get_error(linker->btf);
+ if (err)
+ return err;
+
/* add the special all-zero symbol */
init_sym = add_new_sym(linker, NULL);
if (!init_sym)
@@ -362,8 +413,13 @@ int bpf_linker__add_file(struct bpf_linker *linker, const char *filename)
err = err ?: linker_append_sec_data(linker, &obj);
err = err ?: linker_append_elf_syms(linker, &obj);
err = err ?: linker_append_elf_relos(linker, &obj);
+ err = err ?: linker_append_btf(linker, &obj);
+ err = err ?: linker_append_btf_ext(linker, &obj);
/* free up src_obj resources */
+ free(obj.btf_type_map);
+ btf__free(obj.btf);
+ btf_ext__free(obj.btf_ext);
free(obj.secs);
free(obj.sym_map);
if (obj.elf)
@@ -555,10 +611,22 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename,
break;
case SHT_PROGBITS:
if (strcmp(sec_name, BTF_ELF_SEC) == 0) {
+ obj->btf = btf__new(data->d_buf, shdr->sh_size);
+ err = libbpf_get_error(obj->btf);
+ if (err) {
+ pr_warn("failed to parse .BTF from %s: %d\n", filename, err);
+ return err;
+ }
sec->skipped = true;
continue;
}
if (strcmp(sec_name, BTF_EXT_ELF_SEC) == 0) {
+ obj->btf_ext = btf_ext__new(data->d_buf, shdr->sh_size);
+ err = libbpf_get_error(obj->btf_ext);
+ if (err) {
+ pr_warn("failed to parse .BTF.ext from '%s': %d\n", filename, err);
+ return err;
+ }
sec->skipped = true;
continue;
}
@@ -580,6 +648,9 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename,
}
err = err ?: linker_sanity_check_elf(obj);
+ err = err ?: linker_sanity_check_btf(obj);
+ err = err ?: linker_sanity_check_btf_ext(obj);
+ err = err ?: linker_fixup_btf(obj);
return err;
}
@@ -753,6 +824,69 @@ static int linker_sanity_check_elf(struct src_obj *obj)
return 0;
}
+static int check_btf_type_id(__u32 *type_id, void *ctx)
+{
+ struct btf *btf = ctx;
+
+ if (*type_id > btf__get_nr_types(btf))
+ return -EINVAL;
+
+ return 0;
+}
+
+static int check_btf_str_off(__u32 *str_off, void *ctx)
+{
+ struct btf *btf = ctx;
+ const char *s;
+
+ s = btf__str_by_offset(btf, *str_off);
+
+ if (!s)
+ return -EINVAL;
+
+ return 0;
+}
+
+static int linker_sanity_check_btf(struct src_obj *obj)
+{
+ struct btf_type *t;
+ int i, n, err = 0;
+
+ if (!obj->btf)
+ return 0;
+
+ n = btf__get_nr_types(obj->btf);
+ for (i = 1; i <= n; i++) {
+ t = btf_type_by_id(obj->btf, i);
+
+ err = err ?: btf_type_visit_type_ids(t, check_btf_type_id, obj->btf);
+ err = err ?: btf_type_visit_str_offs(t, check_btf_str_off, obj->btf);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
+static int linker_sanity_check_btf_ext(struct src_obj *obj)
+{
+ int err = 0;
+
+ if (!obj->btf_ext)
+ return 0;
+
+ /* can't use .BTF.ext without .BTF */
+ if (!obj->btf)
+ return -EINVAL;
+
+ err = err ?: btf_ext_visit_type_ids(obj->btf_ext, check_btf_type_id, obj->btf);
+ err = err ?: btf_ext_visit_str_offs(obj->btf_ext, check_btf_str_off, obj->btf);
+ if (err)
+ return err;
+
+ return 0;
+}
+
static int init_sec(struct bpf_linker *linker, struct dst_sec *dst_sec, struct src_sec *src_sec)
{
Elf_Scn *scn;
@@ -763,6 +897,10 @@ static int init_sec(struct bpf_linker *linker, struct dst_sec *dst_sec, struct s
dst_sec->sec_sz = 0;
dst_sec->sec_idx = 0;
+ /* ephemeral sections are just thin section shells lacking most parts */
+ if (src_sec->ephemeral)
+ return 0;
+
scn = elf_newscn(linker->elf);
if (!scn)
return -1;
@@ -891,12 +1029,15 @@ static bool is_data_sec(struct src_sec *sec)
{
if (!sec || sec->skipped)
return false;
+ /* ephemeral sections are data sections, e.g., .kconfig, .ksyms */
+ if (sec->ephemeral)
+ return true;
return sec->shdr->sh_type == SHT_PROGBITS || sec->shdr->sh_type == SHT_NOBITS;
}
static bool is_relo_sec(struct src_sec *sec)
{
- if (!sec || sec->skipped)
+ if (!sec || sec->skipped || sec->ephemeral)
return false;
return sec->shdr->sh_type == SHT_REL;
}
@@ -945,6 +1086,9 @@ static int linker_append_sec_data(struct bpf_linker *linker, struct src_obj *obj
/* record mapped section index */
src_sec->dst_id = dst_sec->id;
+ if (src_sec->ephemeral)
+ continue;
+
err = extend_sec(dst_sec, src_sec);
if (err)
return err;
@@ -1120,6 +1264,339 @@ static int linker_append_elf_relos(struct bpf_linker *linker, struct src_obj *ob
return 0;
}
+static struct src_sec *find_src_sec_by_name(struct src_obj *obj, const char *sec_name)
+{
+ struct src_sec *sec;
+ int i;
+
+ for (i = 1; i < obj->sec_cnt; i++) {
+ sec = &obj->secs[i];
+
+ if (strcmp(sec->sec_name, sec_name) == 0)
+ return sec;
+ }
+
+ return NULL;
+}
+
+static Elf64_Sym *find_sym_by_name(struct src_obj *obj, size_t sec_idx,
+ int sym_type, const char *sym_name)
+{
+ struct src_sec *symtab = &obj->secs[obj->symtab_sec_idx];
+ Elf64_Sym *sym = symtab->data->d_buf;
+ int i, n = symtab->shdr->sh_size / symtab->shdr->sh_entsize;
+ int str_sec_idx = symtab->shdr->sh_link;
+ const char *name;
+
+ for (i = 0; i < n; i++, sym++) {
+ if (sym->st_shndx != sec_idx)
+ continue;
+ if (ELF64_ST_TYPE(sym->st_info) != sym_type)
+ continue;
+
+ name = elf_strptr(obj->elf, str_sec_idx, sym->st_name);
+ if (!name)
+ return NULL;
+
+ if (strcmp(sym_name, name) != 0)
+ continue;
+
+ return sym;
+ }
+
+ return NULL;
+}
+
+static int linker_fixup_btf(struct src_obj *obj)
+{
+ const char *sec_name;
+ struct src_sec *sec;
+ int i, j, n, m;
+
+ n = btf__get_nr_types(obj->btf);
+ for (i = 1; i <= n; i++) {
+ struct btf_var_secinfo *vi;
+ struct btf_type *t;
+
+ t = btf_type_by_id(obj->btf, i);
+ if (btf_kind(t) != BTF_KIND_DATASEC)
+ continue;
+
+ sec_name = btf__str_by_offset(obj->btf, t->name_off);
+ sec = find_src_sec_by_name(obj, sec_name);
+ if (sec) {
+ /* record actual section size, unless ephemeral */
+ if (sec->shdr)
+ t->size = sec->shdr->sh_size;
+ } else {
+ /* BTF can have some sections that are not represented
+ * in ELF, e.g., .kconfig and .ksyms, which are used
+ * for special extern variables. Here we'll
+ * pre-create "section shells" for them to be able to
+ * keep track of extra per-section metadata later
+ * (e.g., BTF variables).
+ */
+ sec = add_src_sec(obj, sec_name);
+ if (!sec)
+ return -ENOMEM;
+
+ sec->ephemeral = true;
+ sec->sec_idx = 0; /* will match UNDEF shndx in ELF */
+ }
+
+ /* remember ELF section and its BTF type ID match */
+ sec->sec_type_id = i;
+
+ /* fix up variable offsets */
+ vi = btf_var_secinfos(t);
+ for (j = 0, m = btf_vlen(t); j < m; j++, vi++) {
+ const struct btf_type *vt = btf__type_by_id(obj->btf, vi->type);
+ const char *var_name = btf__str_by_offset(obj->btf, vt->name_off);
+ int var_linkage = btf_var(vt)->linkage;
+ Elf64_Sym *sym;
+
+ /* no need to patch up static or extern vars */
+ if (var_linkage != BTF_VAR_GLOBAL_ALLOCATED)
+ continue;
+
+ sym = find_sym_by_name(obj, sec->sec_idx, STT_OBJECT, var_name);
+ if (!sym) {
+ pr_warn("failed to find symbol for variable '%s' in section '%s'\n", var_name, sec_name);
+ return -ENOENT;
+ }
+
+ vi->offset = sym->st_value;
+ }
+ }
+
+ return 0;
+}
+
+static int remap_type_id(__u32 *type_id, void *ctx)
+{
+ int *id_map = ctx;
+
+ *type_id = id_map[*type_id];
+
+ return 0;
+}
+
+static int linker_append_btf(struct bpf_linker *linker, struct src_obj *obj)
+{
+ const struct btf_type *t;
+ int i, j, n, start_id, id;
+
+ if (!obj->btf)
+ return 0;
+
+ start_id = btf__get_nr_types(linker->btf) + 1;
+ n = btf__get_nr_types(obj->btf);
+
+ obj->btf_type_map = calloc(n + 1, sizeof(int));
+ if (!obj->btf_type_map)
+ return -ENOMEM;
+
+ for (i = 1; i <= n; i++) {
+ t = btf__type_by_id(obj->btf, i);
+
+ /* DATASECs are handled specially below */
+ if (btf_kind(t) == BTF_KIND_DATASEC)
+ continue;
+
+ id = btf__add_type(linker->btf, obj->btf, t);
+ if (id < 0) {
+ pr_warn("failed to append BTF type #%d from file '%s'\n", i, obj->filename);
+ return id;
+ }
+
+ obj->btf_type_map[i] = id;
+ }
+
+ /* remap all the types except DATASECs */
+ n = btf__get_nr_types(linker->btf);
+ for (i = start_id; i <= n; i++) {
+ struct btf_type *dst_t = btf_type_by_id(linker->btf, i);
+
+ if (btf_type_visit_type_ids(dst_t, remap_type_id, obj->btf_type_map))
+ return -EINVAL;
+ }
+
+ /* append DATASEC info */
+ for (i = 1; i < obj->sec_cnt; i++) {
+ struct src_sec *src_sec;
+ struct dst_sec *dst_sec;
+ const struct btf_var_secinfo *src_var;
+ struct btf_var_secinfo *dst_var;
+
+ src_sec = &obj->secs[i];
+ if (!src_sec->sec_type_id || src_sec->skipped)
+ continue;
+ dst_sec = &linker->secs[src_sec->dst_id];
+
+ t = btf__type_by_id(obj->btf, src_sec->sec_type_id);
+ src_var = btf_var_secinfos(t);
+ n = btf_vlen(t);
+ for (j = 0; j < n; j++, src_var++) {
+ void *sec_vars = dst_sec->sec_vars;
+
+ sec_vars = libbpf_reallocarray(sec_vars,
+ dst_sec->sec_var_cnt + 1,
+ sizeof(*dst_sec->sec_vars));
+ if (!sec_vars)
+ return -ENOMEM;
+
+ dst_sec->sec_vars = sec_vars;
+ dst_sec->sec_var_cnt++;
+
+ dst_var = &dst_sec->sec_vars[dst_sec->sec_var_cnt - 1];
+ dst_var->type = obj->btf_type_map[src_var->type];
+ dst_var->size = src_var->size;
+ dst_var->offset = src_sec->dst_off + src_var->offset;
+ }
+ }
+
+ return 0;
+}
+
+static void *add_btf_ext_rec(struct btf_ext_sec_data *ext_data, const void *src_rec)
+{
+ void *tmp;
+
+ tmp = libbpf_reallocarray(ext_data->recs, ext_data->rec_cnt + 1, ext_data->rec_sz);
+ if (!tmp)
+ return NULL;
+ ext_data->recs = tmp;
+
+ tmp += ext_data->rec_cnt * ext_data->rec_sz;
+ memcpy(tmp, src_rec, ext_data->rec_sz);
+
+ ext_data->rec_cnt++;
+
+ return tmp;
+}
+
+static int linker_append_btf_ext(struct bpf_linker *linker, struct src_obj *obj)
+{
+ const struct btf_ext_info_sec *ext_sec;
+ const char *sec_name, *s;
+ struct src_sec *src_sec;
+ struct dst_sec *dst_sec;
+ int rec_sz, str_off, i;
+
+ if (!obj->btf_ext)
+ return 0;
+
+ rec_sz = obj->btf_ext->func_info.rec_size;
+ for_each_btf_ext_sec(&obj->btf_ext->func_info, ext_sec) {
+ struct bpf_func_info_min *src_rec, *dst_rec;
+
+ sec_name = btf__name_by_offset(obj->btf, ext_sec->sec_name_off);
+ src_sec = find_src_sec_by_name(obj, sec_name);
+ if (!src_sec) {
+ pr_warn("can't find section '%s' referenced from .BTF.ext\n", sec_name);
+ return -EINVAL;
+ }
+ dst_sec = &linker->secs[src_sec->dst_id];
+
+ if (dst_sec->func_info.rec_sz == 0)
+ dst_sec->func_info.rec_sz = rec_sz;
+ if (dst_sec->func_info.rec_sz != rec_sz) {
+ pr_warn("incompatible .BTF.ext record sizes for section '%s'\n", sec_name);
+ return -EINVAL;
+ }
+
+ for_each_btf_ext_rec(&obj->btf_ext->func_info, ext_sec, i, src_rec) {
+ dst_rec = add_btf_ext_rec(&dst_sec->func_info, src_rec);
+ if (!dst_rec)
+ return -ENOMEM;
+
+ dst_rec->insn_off += src_sec->dst_off;
+ dst_rec->type_id = obj->btf_type_map[dst_rec->type_id];
+ }
+ }
+
+ rec_sz = obj->btf_ext->line_info.rec_size;
+ for_each_btf_ext_sec(&obj->btf_ext->line_info, ext_sec) {
+ struct bpf_line_info_min *src_rec, *dst_rec;
+
+ sec_name = btf__name_by_offset(obj->btf, ext_sec->sec_name_off);
+ src_sec = find_src_sec_by_name(obj, sec_name);
+ if (!src_sec) {
+ pr_warn("can't find section '%s' referenced from .BTF.ext\n", sec_name);
+ return -EINVAL;
+ }
+ dst_sec = &linker->secs[src_sec->dst_id];
+
+ if (dst_sec->line_info.rec_sz == 0)
+ dst_sec->line_info.rec_sz = rec_sz;
+ if (dst_sec->line_info.rec_sz != rec_sz) {
+ pr_warn("incompatible .BTF.ext record sizes for section '%s'\n", sec_name);
+ return -EINVAL;
+ }
+
+ for_each_btf_ext_rec(&obj->btf_ext->line_info, ext_sec, i, src_rec) {
+ dst_rec = add_btf_ext_rec(&dst_sec->line_info, src_rec);
+ if (!dst_rec)
+ return -ENOMEM;
+
+ dst_rec->insn_off += src_sec->dst_off;
+
+ s = btf__str_by_offset(obj->btf, src_rec->file_name_off);
+ str_off = btf__add_str(linker->btf, s);
+ if (str_off < 0)
+ return -ENOMEM;
+ dst_rec->file_name_off = str_off;
+
+ s = btf__str_by_offset(obj->btf, src_rec->line_off);
+ str_off = btf__add_str(linker->btf, s);
+ if (str_off < 0)
+ return -ENOMEM;
+ dst_rec->line_off = str_off;
+
+ /* dst_rec->line_col is fine */
+ }
+ }
+
+ rec_sz = obj->btf_ext->core_relo_info.rec_size;
+ for_each_btf_ext_sec(&obj->btf_ext->core_relo_info, ext_sec) {
+ struct bpf_core_relo *src_rec, *dst_rec;
+
+ sec_name = btf__name_by_offset(obj->btf, ext_sec->sec_name_off);
+ src_sec = find_src_sec_by_name(obj, sec_name);
+ if (!src_sec) {
+ pr_warn("can't find section '%s' referenced from .BTF.ext\n", sec_name);
+ return -EINVAL;
+ }
+ dst_sec = &linker->secs[src_sec->dst_id];
+
+ if (dst_sec->core_relo_info.rec_sz == 0)
+ dst_sec->core_relo_info.rec_sz = rec_sz;
+ if (dst_sec->core_relo_info.rec_sz != rec_sz) {
+ pr_warn("incompatible .BTF.ext record sizes for section '%s'\n", sec_name);
+ return -EINVAL;
+ }
+
+ for_each_btf_ext_rec(&obj->btf_ext->core_relo_info, ext_sec, i, src_rec) {
+ dst_rec = add_btf_ext_rec(&dst_sec->core_relo_info, src_rec);
+ if (!dst_rec)
+ return -ENOMEM;
+
+ dst_rec->insn_off += src_sec->dst_off;
+ dst_rec->type_id = obj->btf_type_map[dst_rec->type_id];
+
+ s = btf__str_by_offset(obj->btf, src_rec->access_str_off);
+ str_off = btf__add_str(linker->btf, s);
+ if (str_off < 0)
+ return -ENOMEM;
+ dst_rec->access_str_off = str_off;
+
+ /* dst_rec->kind is fine */
+ }
+ }
+
+ return 0;
+}
+
int bpf_linker__finalize(struct bpf_linker *linker)
{
struct dst_sec *sec;
@@ -1130,6 +1607,10 @@ int bpf_linker__finalize(struct bpf_linker *linker)
if (!linker->elf)
return -EINVAL;
+ err = finalize_btf(linker);
+ if (err)
+ return err;
+
/* Finalize strings */
strs_sz = strset__data_size(linker->strtab_strs);
strs = strset__data(linker->strtab_strs);
@@ -1149,6 +1630,10 @@ int bpf_linker__finalize(struct bpf_linker *linker)
if (sec->sec_idx == linker->strtab_sec_idx)
continue;
+ /* special ephemeral sections (.ksyms, .kconfig, etc) */
+ if (!sec->scn)
+ continue;
+
sec->data->d_buf = sec->raw_data;
}
@@ -1174,3 +1659,283 @@ int bpf_linker__finalize(struct bpf_linker *linker)
return 0;
}
+
+static int emit_elf_data_sec(struct bpf_linker *linker, const char *sec_name,
+ size_t align, const void *raw_data, size_t raw_sz)
+{
+ Elf_Scn *scn;
+ Elf_Data *data;
+ Elf64_Shdr *shdr;
+ int name_off;
+
+ name_off = strset__add_str(linker->strtab_strs, sec_name);
+ if (name_off < 0)
+ return name_off;
+
+ scn = elf_newscn(linker->elf);
+ if (!scn)
+ return -ENOMEM;
+ data = elf_newdata(scn);
+ if (!data)
+ return -ENOMEM;
+ shdr = elf64_getshdr(scn);
+ if (!shdr)
+ return -EINVAL;
+
+ shdr->sh_name = name_off;
+ shdr->sh_type = SHT_PROGBITS;
+ shdr->sh_flags = 0;
+ shdr->sh_size = raw_sz;
+ shdr->sh_link = 0;
+ shdr->sh_info = 0;
+ shdr->sh_addralign = align;
+ shdr->sh_entsize = 0;
+
+ data->d_type = ELF_T_BYTE;
+ data->d_size = raw_sz;
+ data->d_buf = (void *)raw_data;
+ data->d_align = align;
+ data->d_off = 0;
+
+ return 0;
+}
+
+static int finalize_btf(struct bpf_linker *linker)
+{
+ struct btf *btf = linker->btf;
+ const void *raw_data;
+ int i, j, id, err;
+ __u32 raw_sz;
+
+ /* bail out if no BTF data was produced */
+ if (btf__get_nr_types(linker->btf) == 0)
+ return 0;
+
+ for (i = 1; i < linker->sec_cnt; i++) {
+ struct dst_sec *sec = &linker->secs[i];
+
+ if (!sec->sec_var_cnt)
+ continue;
+
+ id = btf__add_datasec(btf, sec->sec_name, sec->sec_sz);
+ if (id < 0) {
+ pr_warn("failed to add consolidated BTF type for datasec '%s': %d\n",
+ sec->sec_name, id);
+ return id;
+ }
+
+ for (j = 0; j < sec->sec_var_cnt; j++) {
+ struct btf_var_secinfo *vi = &sec->sec_vars[j];
+
+ if (btf__add_datasec_var_info(btf, vi->type, vi->offset, vi->size))
+ return -EINVAL;
+ }
+ }
+
+ err = finalize_btf_ext(linker);
+ if (err) {
+ pr_warn(".BTF.ext generation failed: %d\n", err);
+ return err;
+ }
+
+ err = btf__dedup(linker->btf, linker->btf_ext, NULL);
+ if (err) {
+ pr_warn("BTF dedup failed: %d\n", err);
+ return err;
+ }
+
+ /* Emit .BTF section */
+ raw_data = btf__get_raw_data(linker->btf, &raw_sz);
+ if (!raw_data)
+ return -ENOMEM;
+
+ err = emit_elf_data_sec(linker, BTF_ELF_SEC, 8, raw_data, raw_sz);
+ if (err) {
+ pr_warn("failed to write out .BTF ELF section: %d\n", err);
+ return err;
+ }
+
+ /* Emit .BTF.ext section */
+ if (linker->btf_ext) {
+ raw_data = btf_ext__get_raw_data(linker->btf_ext, &raw_sz);
+ if (!raw_data)
+ return -ENOMEM;
+
+ err = emit_elf_data_sec(linker, BTF_EXT_ELF_SEC, 8, raw_data, raw_sz);
+ if (err) {
+ pr_warn("failed to write out .BTF.ext ELF section: %d\n", err);
+ return err;
+ }
+ }
+
+ return 0;
+}
+
+static int emit_btf_ext_data(struct bpf_linker *linker, void *output,
+ const char *sec_name, struct btf_ext_sec_data *sec_data)
+{
+ struct btf_ext_info_sec *sec_info;
+ void *cur = output;
+ int str_off;
+ size_t sz;
+
+ if (!sec_data->rec_cnt)
+ return 0;
+
+ str_off = btf__add_str(linker->btf, sec_name);
+ if (str_off < 0)
+ return -ENOMEM;
+
+ sec_info = cur;
+ sec_info->sec_name_off = str_off;
+ sec_info->num_info = sec_data->rec_cnt;
+ cur += sizeof(struct btf_ext_info_sec);
+
+ sz = sec_data->rec_cnt * sec_data->rec_sz;
+ memcpy(cur, sec_data->recs, sz);
+ cur += sz;
+
+ return cur - output;
+}
+
+static int finalize_btf_ext(struct bpf_linker *linker)
+{
+ size_t funcs_sz = 0, lines_sz = 0, core_relos_sz = 0, total_sz = 0;
+ size_t func_rec_sz = 0, line_rec_sz = 0, core_relo_rec_sz = 0;
+ struct btf_ext_header *hdr;
+ void *data, *cur;
+ int i, err, sz;
+
+ /* validate that all sections have the same .BTF.ext record sizes
+ * and calculate total data size for each type of data (func info,
+ * line info, core relos)
+ */
+ for (i = 1; i < linker->sec_cnt; i++) {
+ struct dst_sec *sec = &linker->secs[i];
+
+ if (sec->func_info.rec_cnt) {
+ if (func_rec_sz == 0)
+ func_rec_sz = sec->func_info.rec_sz;
+ if (func_rec_sz != sec->func_info.rec_sz) {
+ pr_warn("mismatch in func_info record size %zu != %u\n",
+ func_rec_sz, sec->func_info.rec_sz);
+ return -EINVAL;
+ }
+
+ funcs_sz += sizeof(struct btf_ext_info_sec) + func_rec_sz * sec->func_info.rec_cnt;
+ }
+ if (sec->line_info.rec_cnt) {
+ if (line_rec_sz == 0)
+ line_rec_sz = sec->line_info.rec_sz;
+ if (line_rec_sz != sec->line_info.rec_sz) {
+ pr_warn("mismatch in line_info record size %zu != %u\n",
+ line_rec_sz, sec->line_info.rec_sz);
+ return -EINVAL;
+ }
+
+ lines_sz += sizeof(struct btf_ext_info_sec) + line_rec_sz * sec->line_info.rec_cnt;
+ }
+ if (sec->core_relo_info.rec_cnt) {
+ if (core_relo_rec_sz == 0)
+ core_relo_rec_sz = sec->core_relo_info.rec_sz;
+ if (core_relo_rec_sz != sec->core_relo_info.rec_sz) {
+ pr_warn("mismatch in core_relo_info record size %zu != %u\n",
+ core_relo_rec_sz, sec->core_relo_info.rec_sz);
+ return -EINVAL;
+ }
+
+ core_relos_sz += sizeof(struct btf_ext_info_sec) + core_relo_rec_sz * sec->core_relo_info.rec_cnt;
+ }
+ }
+
+ if (!funcs_sz && !lines_sz && !core_relos_sz)
+ return 0;
+
+ total_sz += sizeof(struct btf_ext_header);
+ if (funcs_sz) {
+ funcs_sz += sizeof(__u32); /* record size prefix */
+ total_sz += funcs_sz;
+ }
+ if (lines_sz) {
+ lines_sz += sizeof(__u32); /* record size prefix */
+ total_sz += lines_sz;
+ }
+ if (core_relos_sz) {
+ core_relos_sz += sizeof(__u32); /* record size prefix */
+ total_sz += core_relos_sz;
+ }
+
+ cur = data = calloc(1, total_sz);
+ if (!data)
+ return -ENOMEM;
+
+ hdr = cur;
+ hdr->magic = BTF_MAGIC;
+ hdr->version = BTF_VERSION;
+ hdr->flags = 0;
+ hdr->hdr_len = sizeof(struct btf_ext_header);
+ cur += sizeof(struct btf_ext_header);
+
+ /* All offsets are in bytes relative to the end of this header */
+ hdr->func_info_off = 0;
+ hdr->func_info_len = funcs_sz;
+ hdr->line_info_off = funcs_sz;
+ hdr->line_info_len = lines_sz;
+ hdr->core_relo_off = funcs_sz + lines_sz;;
+ hdr->core_relo_len = core_relos_sz;
+
+ if (funcs_sz) {
+ *(__u32 *)cur = func_rec_sz;
+ cur += sizeof(__u32);
+
+ for (i = 1; i < linker->sec_cnt; i++) {
+ struct dst_sec *sec = &linker->secs[i];
+
+ sz = emit_btf_ext_data(linker, cur, sec->sec_name, &sec->func_info);
+ if (sz < 0)
+ return sz;
+
+ cur += sz;
+ }
+ }
+
+ if (lines_sz) {
+ *(__u32 *)cur = line_rec_sz;
+ cur += sizeof(__u32);
+
+ for (i = 1; i < linker->sec_cnt; i++) {
+ struct dst_sec *sec = &linker->secs[i];
+
+ sz = emit_btf_ext_data(linker, cur, sec->sec_name, &sec->line_info);
+ if (sz < 0)
+ return sz;
+
+ cur += sz;
+ }
+ }
+
+ if (core_relos_sz) {
+ *(__u32 *)cur = core_relo_rec_sz;
+ cur += sizeof(__u32);
+
+ for (i = 1; i < linker->sec_cnt; i++) {
+ struct dst_sec *sec = &linker->secs[i];
+
+ sz = emit_btf_ext_data(linker, cur, sec->sec_name, &sec->core_relo_info);
+ if (sz < 0)
+ return sz;
+
+ cur += sz;
+ }
+ }
+
+ linker->btf_ext = btf_ext__new(data, total_sz);
+ err = libbpf_get_error(linker->btf_ext);
+ if (err) {
+ linker->btf_ext = NULL;
+ pr_warn("failed to parse final .BTF.ext data: %d\n", err);
+ return err;
+ }
+
+ return 0;
+}