07d90c72ef
Andrii Nakryiko says: ==================== This patch set fixes and improves BPF verifier's precision tracking logic for SCALAR registers. Patches #1 and #2 are bug fixes discovered while working on these changes. Patch #3 enables precision tracking for BPF programs that contain subprograms. This was disabled before and prevent any modern BPF programs that use subprograms from enjoying the benefits of SCALAR (im)precise logic. Patch #4 is few lines of code changes and many lines of explaining why those changes are correct. We establish why ignoring precise markings in current state is OK. Patch #5 build on explanation in patch #4 and pushes it to the limit by forcefully forgetting inherited precise markins. Patch #4 by itself doesn't prevent current state from having precise=true SCALARs, so patch #5 is necessary to prevent such stray precise=true registers from creeping in. Patch #6 adjusts test_align selftests to work around BPF verifier log's limitations when it comes to interactions between state output and precision backtracking output. Overall, the goal of this patch set is to make BPF verifier's state tracking a bit more efficient by trying to preserve as much generality in checkpointed states as possible. v1->v2: - adjusted patch #1 commit message to make it clear we are fixing forward step, not precision backtracking (Alexei); - moved last_idx/first_idx verbose logging up to make it clear when global func reaches the first empty state (Alexei). ==================== 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.