bpfloader - add writeProcSysFile failure mode comment
as discovered on some sunfish 4.14 kernels
Note that CONFIG_BPF_JIT=y is required for 4.14-r,
but sunfish was 4.14-q and thus missed VINTF enforcement of this
(it was enabled for b1c1[blueline/crosshatch]/bonito & floral[flame/coral]).
Bug: 262115216
Test: N/A, comment only
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: If6ee9f7f9e449526602fd0e5cffd49f132e681a2
diff --git a/bpfloader/BpfLoader.cpp b/bpfloader/BpfLoader.cpp
index 313b097..1ad5a7d 100644
--- a/bpfloader/BpfLoader.cpp
+++ b/bpfloader/BpfLoader.cpp
@@ -264,9 +264,13 @@
// Enable the eBPF JIT -- but do note that on 64-bit kernels it is likely
// already force enabled by the kernel config option BPF_JIT_ALWAYS_ON
+ // (Note: this (open) will fail with ENOENT 'No such file or directory' if
+ // kernel does not have CONFIG_BPF_JIT=y)
if (writeProcSysFile("/proc/sys/net/core/bpf_jit_enable", "1\n")) return 1;
// Enable JIT kallsyms export for privileged users only
+ // (Note: this (open) will fail with ENOENT 'No such file or directory' if
+ // kernel does not have CONFIG_HAVE_EBPF_JIT=y)
if (writeProcSysFile("/proc/sys/net/core/bpf_jit_kallsyms", "1\n")) return 1;
// This is ugly... but this allows InProcessTethering which runs as system_server,