8f50d5c423
Kui-Feng Lee says: ==================== The BPF struct_ops previously only allowed for one page to be used for the trampolines of all links in a map. However, we have recently run out of space due to the large number of BPF program links. By allocating additional pages when we exhaust an existing page, we can accommodate more links in a single map. The variable st_map->image has been changed to st_map->image_pages, and its type has been changed to an array of pointers to buffers of PAGE_SIZE. Additional pages are allocated when all existing pages are exhausted. The test case loads a struct_ops maps having 40 programs. Their trampolines takes about 6.6k+ bytes over 1.5 pages on x86. --- Major differences from v3: - Refactor buffer allocations to bpf_struct_ops_tramp_buf_alloc() and bpf_struct_ops_tramp_buf_free(). Major differences from v2: - Move image buffer allocation to bpf_struct_ops_prepare_trampoline(). Major differences from v1: - Always free pages if failing to update. - Allocate 8 pages at most. v3: https://lore.kernel.org/all/20240224030302.1500343-1-thinker.li@gmail.com/ v2: https://lore.kernel.org/all/20240221225911.757861-1-thinker.li@gmail.com/ v1: https://lore.kernel.org/all/20240216182828.201727-1-thinker.li@gmail.com/ ==================== Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
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.