enable btf for offload.o & test.o
The objdump -x visible changes between old and new versions of the
mainline shipped .o files are really very minimal: just the inclusion
of a new .BTF section and changes/removals of some 'l' entries from
the symbol table. However, it turns out a change to symbol ordering
is incompatible with BpfLoader <v0.10 which doesn't know to skip
non-function symbols, and as such enabling btf requires a little
bit of gymnastics.
After:
$ adbz shell ls -l /apex/com.android.tethering/etc/bpf/*.o
-rw-r--r-- 1 system system 118352 1969-12-31 16:00 /apex/com.android.tethering/etc/bpf/offload.o
-rw-r--r-- 1 system system 123424 1969-12-31 16:00 /apex/com.android.tethering/etc/bpf/offload@btf.o
-rw-r--r-- 1 system system 2232 1969-12-31 16:00 /apex/com.android.tethering/etc/bpf/test.o
-rw-r--r-- 1 system system 6376 1969-12-31 16:00 /apex/com.android.tethering/etc/bpf/test@btf.o
$ adbz shell logcat -d | egrep offload.*[.]o
07-15 13:10:43.358 0 0 D LibBpfLoader: Loading critical for tethering ELF object /apex/com.android.tethering/etc/bpf/offload.o with license Apache 2.0
07-15 13:10:43.359 0 0 I LibBpfLoader: BpfLoader version 0x00019 ignoring ELF object /apex/com.android.tethering/etc/bpf/offload.o with max ver 0x00019
07-15 13:10:43.359 0 0 I bpfloader: Loaded object: /apex/com.android.tethering/etc/bpf/offload.o
07-15 13:10:43.374 0 0 D LibBpfLoader: Loading critical for tethering ELF object /apex/com.android.tethering/etc/bpf/offload@btf.o with license Apache 2.0
07-15 13:10:43.375 0 0 I LibBpfLoader: BpfLoader version 0x00019 processing ELF object /apex/com.android.tethering/etc/bpf/offload@btf.o with ver [0x00019,0x10000)
07-15 13:10:43.452 0 0 D LibBpfLoader: map_fd found at 0 is 6 in /apex/com.android.tethering/etc/bpf/offload@btf.o
...
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Id658818d1d42763358747523615b7918d312588e
diff --git a/bpf_progs/test.c b/bpf_progs/test.c
index f2fcc8c..e22fe2a 100644
--- a/bpf_progs/test.c
+++ b/bpf_progs/test.c
@@ -18,8 +18,16 @@
#include <linux/in.h>
#include <linux/ip.h>
+#ifdef BTF
+// BTF is incompatible with bpfloaders < v0.10, hence for S (v0.2) we must
+// ship a different file than for later versions, but we need bpfloader v0.25+
+// for obj@ver.o support
+#define BPFLOADER_MIN_VER BPFLOADER_OBJ_AT_VER_VERSION
+#else /* BTF */
// The resulting .o needs to load on the Android S bpfloader
#define BPFLOADER_MIN_VER BPFLOADER_S_VERSION
+#define BPFLOADER_MAX_VER BPFLOADER_OBJ_AT_VER_VERSION
+#endif /* BTF */
#include "bpf_helpers.h"
#include "bpf_net_helpers.h"