Merge branch 'libbpf-extern-followups'

Andrii Nakryiko says:

====================
Based on latest feedback and discussions, this patch set implements the
following changes:

- Kconfig-provided externs have to be in .kconfig section, for which
  bpf_helpers.h provides convenient __kconfig macro (Daniel);
- instead of allowing to override Kconfig file path, switch this to ability to
  extend and override system Kconfig with user-provided custom values (Alexei);
- BTF is required when externs are used.
====================

Signed-off-by: Alexei Starovoitov <[email protected]>

Author: Alexei Starovoitov

tools/bpf/bpftool/gen.c

@@ -83,8 +83,8 @@ static const char *get_map_ident(const struct bpf_map *map)
 		return "rodata";
 	else if (str_has_suffix(name, ".bss"))
 		return "bss";
-	else if (str_has_suffix(name, ".extern"))
-		return "externs"; /* extern is a C keyword */
+	else if (str_has_suffix(name, ".kconfig"))
+		return "kconfig";
 	else
 		return NULL;
 }
@@ -112,8 +112,8 @@ static int codegen_datasec_def(struct bpf_object *obj,
 		sec_ident = "bss";
 	else if (strcmp(sec_name, ".rodata") == 0)
 		sec_ident = "rodata";
-	else if (strcmp(sec_name, ".extern") == 0)
-		sec_ident = "externs"; /* extern is a C keyword */
+	else if (strcmp(sec_name, ".kconfig") == 0)
+		sec_ident = "kconfig";
 	else
 		return 0;
 

tools/lib/bpf/bpf_helpers.h

@@ -53,4 +53,6 @@ enum libbpf_tristate {
 	TRI_MODULE = 2,
 };
 
+#define __kconfig __attribute__((section(".kconfig")))
+
 #endif