#define __weak __attribute__((weak))
#endif
+/*
+ * Use __hidden attribute to mark a non-static BPF subprogram effectively
+ * static for BPF verifier's verification algorithm purposes, allowing more
+ * extensive and permissive BPF verification process, taking into account
+ * subprogram's caller context.
+ */
+#define __hidden __attribute__((visibility("hidden")))
+
/* When utilizing vmlinux.h with BPF CO-RE, user BPF programs can't include
* any system-level headers (such as stddef.h, linux/version.h, etc), and
* commonly-used macros like NULL and KERNEL_VERSION aren't available through
static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
static const struct btf_type *
skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id);
+static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog);
static int __base_pr(enum libbpf_print_level level, const char *format,
va_list args)
bpf_program_clear_priv_t clear_priv;
bool load;
+ bool mark_btf_static;
enum bpf_prog_type type;
enum bpf_attach_type expected_attach_type;
int prog_ifindex;
if (err)
return err;
+ /* if function is a global/weak symbol, but has hidden
+ * visibility (STV_HIDDEN), mark its BTF FUNC as static to
+ * enable more permissive BPF verification mode with more
+ * outside context available to BPF verifier
+ */
+ if (GELF_ST_BIND(sym.st_info) != STB_LOCAL
+ && GELF_ST_VISIBILITY(sym.st_other) == STV_HIDDEN)
+ prog->mark_btf_static = true;
+
nr_progs++;
obj->nr_programs = nr_progs;
{
struct btf *kern_btf = obj->btf;
bool btf_mandatory, sanitize;
- int err = 0;
+ int i, err = 0;
if (!obj->btf)
return 0;
return 0;
}
+ /* Even though some subprogs are global/weak, user might prefer more
+ * permissive BPF verification process that BPF verifier performs for
+ * static functions, taking into account more context from the caller
+ * functions. In such case, they need to mark such subprogs with
+ * __attribute__((visibility("hidden"))) and libbpf will adjust
+ * corresponding FUNC BTF type to be marked as static and trigger more
+ * involved BPF verification process.
+ */
+ for (i = 0; i < obj->nr_programs; i++) {
+ struct bpf_program *prog = &obj->programs[i];
+ struct btf_type *t;
+ const char *name;
+ int j, n;
+
+ if (!prog->mark_btf_static || !prog_is_subprog(obj, prog))
+ continue;
+
+ n = btf__get_nr_types(obj->btf);
+ for (j = 1; j <= n; j++) {
+ t = btf_type_by_id(obj->btf, j);
+ if (!btf_is_func(t) || btf_func_linkage(t) != BTF_FUNC_GLOBAL)
+ continue;
+
+ name = btf__str_by_offset(obj->btf, t->name_off);
+ if (strcmp(name, prog->name) != 0)
+ continue;
+
+ t->info = btf_type_info(BTF_KIND_FUNC, BTF_FUNC_STATIC, 0);
+ break;
+ }
+ }
+
sanitize = btf_needs_sanitization(obj);
if (sanitize) {
const void *raw_data;
#pragma GCC poison reallocarray
#include "libbpf.h"
+#include "btf.h"
#ifndef EM_BPF
#define EM_BPF 247
struct btf_type *btf_type_by_id(struct btf *btf, __u32 type_id);
+static inline __u32 btf_type_info(int kind, int vlen, int kflag)
+{
+ return (kflag << 31) | (kind << 24) | vlen;
+}
+
void *libbpf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,
size_t cur_cnt, size_t max_cnt, size_t add_cnt);
int libbpf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt);