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It's straightforward to prove that kptr_struct_meta must be non-NULL for
any valid call to these kfuncs:
* btf_parse_struct_metas in btf.c creates a btf_struct_meta for any
struct in user BTF with a special field (e.g. bpf_refcount,
{rb,list}_node). These are stored in that BTF's struct_meta_tab.
* __process_kf_arg_ptr_to_graph_node in verifier.c ensures that nodes
have {rb,list}_node field and that it's at the correct offset.
Similarly, check_kfunc_args ensures bpf_refcount field existence for
node param to bpf_refcount_acquire.
* So a btf_struct_meta must have been created for the struct type of
node param to these kfuncs
* That BTF and its struct_meta_tab are guaranteed to still be around.
Any arbitrary {rb,list} node the BPF program interacts with either:
came from bpf_obj_new or a collection removal kfunc in the same
program, in which case the BTF is associated with the program and
still around; or came from bpf_kptr_xchg, in which case the BTF was
associated with the map and is still around
Instead of silently continuing with NULL struct_meta, which caused
confusing bugs such as those addressed by commit
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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 | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .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 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.