Daniel Borkmann 7514cd2f6d bpf, x64: increase number of passes
commit 6007b080d2e2adb7af22bf29165f0594ea12b34c upstream.

In Cilium some of the main programs we run today are hitting 9 passes
on x64's JIT compiler, and we've had cases already where we surpassed
the limit where the JIT then punts the program to the interpreter
instead, leading to insertion failures due to CONFIG_BPF_JIT_ALWAYS_ON
or insertion failures due to the prog array owner being JITed but the
program to insert not (both must have the same JITed/non-JITed property).

One concrete case the program image shrunk from 12,767 bytes down to
10,288 bytes where the image converged after 16 steps. I've measured
that this took 340us in the JIT until it converges on my i7-6600U. Thus,
increase the original limit we had from day one where the JIT covered
cBPF only back then before we run into the case (as similar with the
complexity limit) where we trip over this and hit program rejections.
Also add a cond_resched() into the compilation loop, the JIT process
runs without any locks and may sleep anyway.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-28 18:24:51 +02:00
2018-03-28 18:24:51 +02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.
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