commit 07375e26a376107b564a3f3837345b6c0fbce5be
author Maciej Żenczykowski <maze@google.com> Wed Feb 19 14:23:59 2020 -0800
committer Maciej Żenczykowski <maze@google.com> Wed Feb 19 15:46:23 2020 -0800
tree c5043bd1554dd62c7fdd3cf8fd9edfc9a93d4795
parent cd994cd63768ff79ae5c13c136a54887dd6c2701

add support for marking ebpf programs as being only for some kernel versions

Some ebpf code cannot be loaded on too old kernels.

Sometimes we want a different - more advanced - version of an ebpf program
to be loaded on a newer kernel.

Test: build, atest
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I9e93e7246951916e6d60544575337a7a19c82886

libbpf_android/Loader.cpp

diff --git a/libbpf_android/Loader.cpp b/libbpf_android/Loader.cpp
index 8f139a3..ce710a4 100644
--- a/libbpf_android/Loader.cpp
+++ b/libbpf_android/Loader.cpp
@@ -30,6 +30,7 @@
 
 #include "../progs/include/bpf_map_def.h"
 #include "LoaderUtils.h"
+#include "bpf/BpfUtils.h"
 #include "include/libbpf_android.h"
 
 #include <cstdlib>
@@ -531,9 +532,10 @@
 }
 
 static int loadCodeSections(const char* elfPath, vector<codeSection>& cs, const string& license) {
-    int ret, fd, kvers;
+    unsigned kvers = kernelVersion();
+    int ret, fd;
 
-    if ((kvers = getMachineKvers()) < 0) return -1;
+    if (!kvers) return -1;
 
     string fname = pathToFilename(string(elfPath), true);
 
@@ -541,6 +543,11 @@
         string progPinLoc;
         bool reuse = false;
 
+        if (cs[i].prog_def.has_value()) {
+            if (kvers < cs[i].prog_def->min_kver) continue;
+            if (kvers >= cs[i].prog_def->max_kver) continue;
+        }
+
         // Format of pin location is
         // /sys/fs/bpf/prog_<filename>_<mapname>
         progPinLoc = string(BPF_FS_PATH) + "prog_" + fname + "_" + cs[i].name;