mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-05 20:33:49 -04:00
389f263b60
This is the main patch for the logics of BPF-to-BPF calls in the nfp driver. The functions called on BPF_JUMP | BPF_CALL and BPF_JUMP | BPF_EXIT were used to call helpers and exit from the program, respectively; make them usable for calling into, or returning from, a BPF subprogram as well. For all calls, push the return address as well as the callee-saved registers (R6 to R9) to the stack, and pop them upon returning from the calls. In order to limit the overhead in terms of instruction number, this is done through dedicated subroutines. Jumping to the callee actually consists in jumping to the subroutine, that "returns" to the callee: this will require some fixup for passing the address in a later patch. Similarly, returning consists in jumping to the subroutine, which pops registers and then return directly to the caller (but no fixup is needed here). Return to the caller is performed with the RTN instruction newly added to the JIT. For the few steps where we need to know what subprogram an instruction belongs to, the struct nfp_insn_meta is extended with a new subprog_idx field. Note that checks on the available stack size, to take into account the additional requirements associated to BPF-to-BPF calls (storing R6-R9 and return addresses), are added in a later patch. Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com> Signed-off-by: Jiong Wang <jiong.wang@netronome.com> Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.