in compile/remote-compile/lbc/libbpf/src/linker.c [1291:1481]
static bool glob_sym_btf_matches(const char *sym_name, bool exact,
const struct btf *btf1, __u32 id1,
const struct btf *btf2, __u32 id2)
{
const struct btf_type *t1, *t2;
bool is_static1, is_static2;
const char *n1, *n2;
int i, n;
recur:
n1 = n2 = NULL;
t1 = skip_mods_and_typedefs(btf1, id1, &id1);
t2 = skip_mods_and_typedefs(btf2, id2, &id2);
/* check if only one side is FWD, otherwise handle with common logic */
if (!exact && btf_is_fwd(t1) != btf_is_fwd(t2)) {
n1 = btf__str_by_offset(btf1, t1->name_off);
n2 = btf__str_by_offset(btf2, t2->name_off);
if (strcmp(n1, n2) != 0) {
pr_warn("global '%s': incompatible forward declaration names '%s' and '%s'\n",
sym_name, n1, n2);
return false;
}
/* validate if FWD kind matches concrete kind */
if (btf_is_fwd(t1)) {
if (btf_kflag(t1) && btf_is_union(t2))
return true;
if (!btf_kflag(t1) && btf_is_struct(t2))
return true;
pr_warn("global '%s': incompatible %s forward declaration and concrete kind %s\n",
sym_name, btf_kflag(t1) ? "union" : "struct", btf_kind_str(t2));
} else {
if (btf_kflag(t2) && btf_is_union(t1))
return true;
if (!btf_kflag(t2) && btf_is_struct(t1))
return true;
pr_warn("global '%s': incompatible %s forward declaration and concrete kind %s\n",
sym_name, btf_kflag(t2) ? "union" : "struct", btf_kind_str(t1));
}
return false;
}
if (btf_kind(t1) != btf_kind(t2)) {
pr_warn("global '%s': incompatible BTF kinds %s and %s\n",
sym_name, btf_kind_str(t1), btf_kind_str(t2));
return false;
}
switch (btf_kind(t1)) {
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
case BTF_KIND_ENUM:
case BTF_KIND_FWD:
case BTF_KIND_FUNC:
case BTF_KIND_VAR:
n1 = btf__str_by_offset(btf1, t1->name_off);
n2 = btf__str_by_offset(btf2, t2->name_off);
if (strcmp(n1, n2) != 0) {
pr_warn("global '%s': incompatible %s names '%s' and '%s'\n",
sym_name, btf_kind_str(t1), n1, n2);
return false;
}
break;
default:
break;
}
switch (btf_kind(t1)) {
case BTF_KIND_UNKN: /* void */
case BTF_KIND_FWD:
return true;
case BTF_KIND_INT:
case BTF_KIND_FLOAT:
case BTF_KIND_ENUM:
/* ignore encoding for int and enum values for enum */
if (t1->size != t2->size) {
pr_warn("global '%s': incompatible %s '%s' size %u and %u\n",
sym_name, btf_kind_str(t1), n1, t1->size, t2->size);
return false;
}
return true;
case BTF_KIND_PTR:
/* just validate overall shape of the referenced type, so no
* contents comparison for struct/union, and allowd fwd vs
* struct/union
*/
exact = false;
id1 = t1->type;
id2 = t2->type;
goto recur;
case BTF_KIND_ARRAY:
/* ignore index type and array size */
id1 = btf_array(t1)->type;
id2 = btf_array(t2)->type;
goto recur;
case BTF_KIND_FUNC:
/* extern and global linkages are compatible */
is_static1 = btf_func_linkage(t1) == BTF_FUNC_STATIC;
is_static2 = btf_func_linkage(t2) == BTF_FUNC_STATIC;
if (is_static1 != is_static2) {
pr_warn("global '%s': incompatible func '%s' linkage\n", sym_name, n1);
return false;
}
id1 = t1->type;
id2 = t2->type;
goto recur;
case BTF_KIND_VAR:
/* extern and global linkages are compatible */
is_static1 = btf_var(t1)->linkage == BTF_VAR_STATIC;
is_static2 = btf_var(t2)->linkage == BTF_VAR_STATIC;
if (is_static1 != is_static2) {
pr_warn("global '%s': incompatible var '%s' linkage\n", sym_name, n1);
return false;
}
id1 = t1->type;
id2 = t2->type;
goto recur;
case BTF_KIND_STRUCT:
case BTF_KIND_UNION: {
const struct btf_member *m1, *m2;
if (!exact)
return true;
if (btf_vlen(t1) != btf_vlen(t2)) {
pr_warn("global '%s': incompatible number of %s fields %u and %u\n",
sym_name, btf_kind_str(t1), btf_vlen(t1), btf_vlen(t2));
return false;
}
n = btf_vlen(t1);
m1 = btf_members(t1);
m2 = btf_members(t2);
for (i = 0; i < n; i++, m1++, m2++) {
n1 = btf__str_by_offset(btf1, m1->name_off);
n2 = btf__str_by_offset(btf2, m2->name_off);
if (strcmp(n1, n2) != 0) {
pr_warn("global '%s': incompatible field #%d names '%s' and '%s'\n",
sym_name, i, n1, n2);
return false;
}
if (m1->offset != m2->offset) {
pr_warn("global '%s': incompatible field #%d ('%s') offsets\n",
sym_name, i, n1);
return false;
}
if (!glob_sym_btf_matches(sym_name, exact, btf1, m1->type, btf2, m2->type))
return false;
}
return true;
}
case BTF_KIND_FUNC_PROTO: {
const struct btf_param *m1, *m2;
if (btf_vlen(t1) != btf_vlen(t2)) {
pr_warn("global '%s': incompatible number of %s params %u and %u\n",
sym_name, btf_kind_str(t1), btf_vlen(t1), btf_vlen(t2));
return false;
}
n = btf_vlen(t1);
m1 = btf_params(t1);
m2 = btf_params(t2);
for (i = 0; i < n; i++, m1++, m2++) {
/* ignore func arg names */
if (!glob_sym_btf_matches(sym_name, exact, btf1, m1->type, btf2, m2->type))
return false;
}
/* now check return type as well */
id1 = t1->type;
id2 = t2->type;
goto recur;
}
/* skip_mods_and_typedefs() make this impossible */
case BTF_KIND_TYPEDEF:
case BTF_KIND_VOLATILE:
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
/* DATASECs are never compared with each other */
case BTF_KIND_DATASEC:
default:
pr_warn("global '%s': unsupported BTF kind %s\n",
sym_name, btf_kind_str(t1));
return false;
}
}