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This commit adds a flow-sensitive, context-sensitive, path-insensitive data flow analysis for live stack slots: - flow-sensitive: uses program control flow graph to compute data flow values; - context-sensitive: collects data flow values for each possible call chain in a program; - path-insensitive: does not distinguish between separate control flow graph paths reaching the same instruction. Compared to the current path-sensitive analysis, this approach trades some precision for not having to enumerate every path in the program. This gives a theoretical capability to run the analysis before main verification pass. See cover letter for motivation. The basic idea is as follows: - Data flow values indicate stack slots that might be read and stack slots that are definitely written. - Data flow values are collected for each (call chain, instruction number) combination in the program. - Within a subprogram, data flow values are propagated using control flow graph. - Data flow values are transferred from entry instructions of callee subprograms to call sites in caller subprograms. In other words, a tree of all possible call chains is constructed. Each node of this tree represents a subprogram. Read and write marks are collected for each instruction of each node. Live stack slots are first computed for lower level nodes. Then, information about outer stack slots that might be read or are definitely written by a subprogram is propagated one level up, to the corresponding call instructions of the upper nodes. Procedure repeats until root node is processed. In the absence of value range analysis, stack read/write marks are collected during main verification pass, and data flow computation is triggered each time verifier.c:states_equal() needs to query the information. Implementation details are documented in kernel/bpf/liveness.c. Quantitative data about verification performance changes and memory consumption is in the cover letter. Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20250918-callchain-sensitive-liveness-v3-6-c3cd27bacc60@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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 reStructuredText 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.