libbpf: enforce strict libbpf 1.0 behaviors

Remove support for legacy features and behaviors that previously had to
be disabled by calling libbpf_set_strict_mode():
  - legacy BPF map definitions are not supported now;
  - RLIMIT_MEMLOCK auto-setting, if necessary, is always on (but see
    libbpf_set_memlock_rlim());
  - program name is used for program pinning (instead of section name);
  - cleaned up error returning logic;
  - entry BPF programs should have SEC() always.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220627211527.2245459-15-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 4 insertions, 20 deletions

diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index a1ad145ffa74..9cd7829cbe41 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -15,7 +15,6 @@
 #include <linux/err.h>
 #include <fcntl.h>
 #include <unistd.h>
-#include "libbpf_legacy.h"
 #include "relo_core.h"
 
 /* make sure libbpf doesn't use kernel-only integer typedefs */
@@ -478,8 +477,6 @@ int btf_ext_visit_str_offs(struct btf_ext *btf_ext, str_off_visit_fn visit, void
 __s32 btf__find_by_name_kind_own(const struct btf *btf, const char *type_name,
 				 __u32 kind);
 
-extern enum libbpf_strict_mode libbpf_mode;
-
 typedef int (*kallsyms_cb_t)(unsigned long long sym_addr, char sym_type,
 			     const char *sym_name, void *ctx);
 
@@ -498,12 +495,8 @@ static inline int libbpf_err(int ret)
  */
 static inline int libbpf_err_errno(int ret)
 {
-	if (libbpf_mode & LIBBPF_STRICT_DIRECT_ERRS)
-		/* errno is already assumed to be set on error */
-		return ret < 0 ? -errno : ret;
-
-	/* legacy: on error return -1 directly and don't touch errno */
-	return ret;
+	/* errno is already assumed to be set on error */
+	return ret < 0 ? -errno : ret;
 }
 
 /* handle error for pointer-returning APIs, err is assumed to be < 0 always */
@@ -511,12 +504,7 @@ static inline void *libbpf_err_ptr(int err)
 {
 	/* set errno on error, this doesn't break anything */
 	errno = -err;
-
-	if (libbpf_mode & LIBBPF_STRICT_CLEAN_PTRS)
-		return NULL;
-
-	/* legacy: encode err as ptr */
-	return ERR_PTR(err);
+	return NULL;
 }
 
 /* handle pointer-returning APIs' error handling */
@@ -526,11 +514,7 @@ static inline void *libbpf_ptr(void *ret)
 	if (IS_ERR(ret))
 		errno = -PTR_ERR(ret);
 
-	if (libbpf_mode & LIBBPF_STRICT_CLEAN_PTRS)
-		return IS_ERR(ret) ? NULL : ret;
-
-	/* legacy: pass-through original pointer */
-	return ret;
+	return IS_ERR(ret) ? NULL : ret;
 }
 
 static inline bool str_is_empty(const char *s)