Palmer Dabbelt palmerdabbelt@google.com writes:
The current stable LLVM BPF backend fails to compile the BPF selftests due to a compiler bug. The bug has been fixed in trunk, but that fix hasn't landed in the binary packages I'm using yet (Fedora arm64). Without this workaround the tests don't compile for me.
This patch triggers a preprocessor warning on LLVM versions that definitely have the bug. The test may be conservative (ie, I'm not sure if 9.1 will have the fix), but it should at least make the current set of stable releases work together.
See https://reviews.llvm.org/D69438 for more information on the fix. I obtained the workaround from https://lore.kernel.org/linux-kselftest/aed8eda7-df20-069b-ea14-f06628984566...
Fixes: 20a9ad2e7136 ("selftests/bpf: add CO-RE relocs array tests") Signed-off-by: Palmer Dabbelt palmerdabbelt@google.com
Having to depend on the latest trunk llvm to compile the selftests is definitely unfortunate. I believe there are some tests that won't work at all without trunk llvm (the fentry/fexit stuff comes to mind; although I'm not sure if they'll fail to compile, just fail to run?). Could we extend this type of checking to any such case?
-Toke