e7d5184b24
Martin KaFai says: ==================== The verifier currently does not save the reg state when spilling <8byte bounded scalar to the stack. The bpf program will be incorrectly rejected when this scalar is refilled to the reg and then used to offset into a packet header. The later patch has a simplified bpf prog from a real use case to demonstrate this case. The current work around is to reparse the packet again such that this offset scalar is close to where the packet data will be accessed to avoid the spill. Thus, the header is parsed twice. The llvm patch [1] will align the <8bytes spill to the 8-byte stack address. This set is to make the necessary changes in verifier to support <8byte scalar spill and refill. [1] https://reviews.llvm.org/D109073 v2: - Changed the xdpwall selftest in patch 3 to trigger a u32 spill at a non 8-byte aligned stack address. The v1 has simplified the real example too much such that it only triggers a u32 spill but does not spill at a non 8-byte aligned stack address. - Changed README.rst in patch 3 to explain the llvm dependency for the xdpwall test. ==================== Signed-off-by: Alexei Starovoitov <ast@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 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.