libbpf: Support CO-RE relocations for multi-prog sections

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Fix up CO-RE relocation code to handle relocations against ELF sections
containing multiple BPF programs. This requires lookup of a BPF program by its
section name and instruction index it contains. While it could have been done
as a simple loop, it could run into performance issues pretty quickly, as
number of CO-RE relocations can be quite large in real-world applications, and
each CO-RE relocation incurs BPF program look up now. So instead of simple
loop, implement a binary search by section name + insn offset.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200903203542.15944-4-andriin@fb.com

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Andrii Nakryiko 2020-09-03 13:35:31 -07:00 • committed by Alexei Starovoitov

parent c112239272

commit db2b8b0642

1 changed files with 74 additions and 8 deletions

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tools/lib/bpf/libbpf.c

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