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Milk-V Jupiter Linux kernel
c22dfdd215
The old behavior of bpf_map_meta_equal was that it compared timer_off to be equal (but not spin_lock_off, because that was not allowed), and did memcmp of kptr_off_tab. Now, we memcmp the btf_record of two bpf_map structs, which has all fields. We preserve backwards compat as we kzalloc the array, so if only spin lock and timer exist in map, we only compare offset while the rest of unused members in the btf_field struct are zeroed out. In case of kptr, btf and everything else is of vmlinux or module, so as long type is same it will match, since kernel btf, module, dtor pointer will be same across maps. Now with list_head in the mix, things are a bit complicated. We implicitly add a requirement that both BTFs are same, because struct btf_field_list_head has btf and value_rec members. We obviously shouldn't force BTFs to be equal by default, as that breaks backwards compatibility. Currently it is only implicitly required due to list_head matching struct btf and value_rec member. value_rec points back into a btf_record stashed in the map BTF (btf member of btf_field_list_head). So that pointer and btf member has to match exactly. Document all these subtle details so that things don't break in the future when touching this code. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Link: https://lore.kernel.org/r/20221118015614.2013203-19-memxor@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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| 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.