mirror of
https://github.com/torvalds/linux.git
synced 2026-07-29 02:31:27 +02:00
Linux kernel source tree
aaf043a568
When building with Clang 20 or newer, there are some objtool warnings from unexpected fallthroughs to other functions: vmlinux.o: warning: objtool: mlx5e_mpwrq_mtts_per_wqe() falls through to next function mlx5e_mpwrq_max_num_entries() vmlinux.o: warning: objtool: mlx5e_mpwrq_max_log_rq_size() falls through to next function mlx5e_get_linear_rq_headroom() LLVM 20 contains an (admittedly problematic [1]) optimization [2] to convert divide by zero into the equivalent of __builtin_unreachable(), which invokes undefined behavior and destroys code generation when it is encountered in a control flow graph. mlx5e_mpwrq_umr_entry_size() returns 0 in the default case of an unrecognized mlx5e_mpwrq_umr_mode value. mlx5e_mpwrq_mtts_per_wqe(), which is inlined into mlx5e_mpwrq_max_log_rq_size(), uses the result of mlx5e_mpwrq_umr_entry_size() in a divide operation without checking for zero, so LLVM is able to infer there will be a divide by zero in this case and invokes undefined behavior. While there is some proposed work to isolate this undefined behavior and avoid the destructive code generation that results in these objtool warnings, code should still be defensive against divide by zero. As the WARN_ONCE() implies that an invalid value should be handled gracefully, return 1 instead of 0 in the default case so that the results of this division operation is always valid. Fixes: |
||
|---|---|---|
| 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.