Add BTF layout to BTF#11316
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Add BTF layout to BTF#11316kernel-patches-daemon-bpf[bot] wants to merge 8 commits intobpf-net_basefrom
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BTF kind layouts provide information to parse BTF kinds. By separating parsing BTF from using all the information it provides, we allow BTF to encode new features even if they cannot be used by readers. This will be helpful in particular for cases where older tools are used to parse newer BTF with kinds the older tools do not recognize; the BTF can still be parsed in such cases using kind layout. The intent is to support encoding of kind layouts optionally so that tools like pahole can add this information. For each kind, we record - length of singular element following struct btf_type - length of each of the btf_vlen() elements following - a (currently unused) flags field The ideas here were discussed at [1], [2]; hence Suggested-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alan Maguire <alan.maguire@oracle.com> [1] https://lore.kernel.org/bpf/CAEf4BzYjWHRdNNw4B=eOXOs_ONrDwrgX4bn=Nuc1g8JPFC34MA@mail.gmail.com/ [2] https://lore.kernel.org/bpf/20230531201936.1992188-1-alan.maguire@oracle.com/
Support reading in layout fixing endian issues on reading; also support writing layout section to raw BTF object. There is not yet an API to populate the layout with meaningful information. As part of this, we need to consider multiple valid BTF header sizes; the original or the layout-extended headers. So to support this, the "struct btf" representation is modified to contain a "struct btf_header" and we copy the valid portion from the raw data to it; this means we can always safely check fields like btf->hdr.layout_len Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
This allows BTF parsing to proceed even if we do not know the kind. Fall back to base BTF layout if layout information is not in split BTF. Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Support encoding of BTF layout data via btf__new_empty_opts(). Current supported opts are base_btf and add_layout. Layout information is maintained in btf.c in the layouts[] array; when BTF is created with the add_layout option it represents the current view of supported BTF kinds. Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
BTF parsing can use layout to navigate unknown kinds, so btf_validate_type() should take layout information into account to avoid failure when an unrecognized kind is met. Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Validate layout if present, but because the kernel must be strict in what it accepts, reject BTF with unsupported kinds, even if they are in the layout information. Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
verify btf__new_empty_opts() adds layouts for all kinds supported, and after adding kind-related types for an unknown kind, ensure that parsing uses this info when that kind is encountered rather than giving up. Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
The "layout" feature will add metadata about BTF kinds to the generated BTF; its absence in pahole will not trigger an error so it is safe to add unconditionally as it will simply be ignored if pahole does not support it. Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=1062522 expired. Closing PR. |
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Pull request for series with
subject: Add BTF layout to BTF
version: 13
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=1062522