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During linking, type IDs in the resulting linked BPF object file can change, and so ldimm64 instructions corresponding to BPF_CORE_TYPE_ID_TARGET and BPF_CORE_TYPE_ID_LOCAL CO-RE relos can get their imm value out of sync with actual CO-RE relocation information that's updated by BPF linker properly during linking process. We could teach BPF linker to adjust such instructions, but it feels a bit too much for linker to re-implement good chunk of bpf_core_patch_insns logic just for this. This is a redundant safety check for TYPE_ID relocations, as the real validation is in matching CO-RE specs, so if that works fine, it's very unlikely that there is something wrong with the instruction itself. So, instead, teach libbpf (and kernel) to ignore insn->imm for BPF_CORE_TYPE_ID_TARGET and BPF_CORE_TYPE_ID_LOCAL relos. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211213010706.100231-1-andrii@kernel.org
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.