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Sandipan Das authored
Once the JITed images for each function in a multi-function program
are generated after the first three JIT passes, we only need to fix
the target address for the branch instruction corresponding to each
bpf-to-bpf function call.

This introduces the following optimizations for reducing the work
done by the JIT compiler when handling multi-function programs:

  [1] Instead of doing two extra passes to fix the bpf function calls,
      do just one as that would be sufficient.

  [2] During the extra pass, only overwrite the instruction sequences
      for the bpf-to-bpf function calls as everything else would still
      remain exactly the same. This also reduces the number of writes
      to the JITed image.

  [3] Do not regenerate the prologue and the epilogue during the extra
      pass as that would be redundant.

Signed-off-by: default avatarSandipan Das <sandipan@linux.ibm.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
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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.