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b0920abe0d
The length of PERF_RECORD_KSYMBOL for BPF is a size of JITed code so it'd be 0 when it's not JITed. The ksymbol is needed to symbolize the code when it gets samples in the region but non-JITed code cannot get samples. Thus it'd be ok to ignore them. Actually it caused a performance issue in the perf tools on old ARM kernels where it can refuse to JIT some BPF codes. It ended up splitting the existing kernel map (kallsyms). And later lookup for a kernel symbol would create a new kernel map from kallsyms and then split it again and again. :( Probably there's a bug in the kernel map/symbol handling in perf tools. But I think we need to fix this anyway. Reported-by: Kevin Nomura <nomurak@google.com> Acked-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/r/20250305232838.128692-1-namhyung@kernel.org Signed-off-by: Namhyung Kim <namhyung@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 reStructuredText 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.