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Under register pressure the llvm may spill registers with bounds into the stack. The verifier has to track them through spill/fill otherwise many kinds of bound errors will be seen. The spill/fill of induction variables was already happening. This patch extends this logic from tracking spill/fill of a constant into any bounded register. There is no need to track spill/fill of unbounded, since no new information will be retrieved from the stack during register fill. Though extra stack difference could cause state pruning to be less effective, no adverse affects were seen from this patch on selftests and on cilium programs. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20201009011240.48506-3-alexei.starovoitov@gmail.com
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.