mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/
synced 2026-10-31 05:15:34 +00:00
No description
- C 96.8%
- Assembly 0.9%
- Rust 0.7%
- Shell 0.6%
- Python 0.5%
- Other 0.3%
4ca24d6abb
Many arm64 and x86_64 CPUs can compute two SHA-256 hashes in nearly the same speed as one, if the instructions are interleaved. This is because SHA-256 is serialized block-by-block, and two interleaved hashes take much better advantage of the CPU's instruction-level parallelism. Meanwhile, a very common use case for SHA-256 hashing in the Linux kernel is dm-verity and fs-verity. Both use a Merkle tree that has a fixed block size, usually 4096 bytes with an empty or 32-byte salt prepended. Usually, many blocks need to be hashed at a time. This is an ideal scenario for 2-way interleaved hashing. To enable this optimization, add a new function sha256_finup_2x() to the SHA-256 library API. It computes the hash of two equal-length messages, starting from a common initial context. For now it always falls back to sequential processing. Later patches will wire up arm64 and x86_64 optimized implementations. Note that the interleaving factor could in principle be higher than 2x. However, that runs into many practical difficulties and CPU throughput limitations. Thus, both the implementations I'm adding are 2x. In the interest of using the simplest solution, the API matches that. Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20250915160819.140019-2-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@kernel.org> |
History
|
|
|---|---|---|
| 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.