ec41817b4a
Add bpf_map__set_autocreate() API that allows user to opt-out from libbpf automatically creating BPF map during BPF object load. This is a useful feature when building CO-RE-enabled BPF application that takes advantage of some new-ish BPF map type (e.g., socket-local storage) if kernel supports it, but otherwise uses some alternative way (e.g., extra HASH map). In such case, being able to disable the creation of a map that kernel doesn't support allows to successfully create and load BPF object file with all its other maps and programs. It's still up to user to make sure that no "live" code in any of their BPF programs are referencing such map instance, which can be achieved by guarding such code with CO-RE relocation check or by using .rodata global variables. If user fails to properly guard such code to turn it into "dead code", libbpf will helpfully post-process BPF verifier log and will provide more meaningful error and map name that needs to be guarded properly. As such, instead of: ; value = bpf_map_lookup_elem(&missing_map, &zero); 4: (85) call unknown#2001000000 invalid func unknown#2001000000 ... user will see: ; value = bpf_map_lookup_elem(&missing_map, &zero); 4: <invalid BPF map reference> BPF map 'missing_map' is referenced but wasn't created Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220428041523.4089853-4-andrii@kernel.org |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| 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.