mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-14 04:09:18 -04:00
d352eca266
Eduard Zingerman says:
====================
support bpf_fastcall patterns for calls to kfuncs
As an extension of [1], allow bpf_fastcall patterns for kfuncs:
- pattern rules are the same as for helpers;
- spill/fill removal is allowed only for kfuncs listed in the
is_fastcall_kfunc_call (under assumption that such kfuncs would
always be members of special_kfunc_list).
Allow bpf_fastcall rewrite for bpf_cast_to_kern_ctx() and
bpf_rdonly_cast() in order to conjure selftests for this feature.
After this patch-set verifier would rewrite the program below:
r2 = 1
*(u64 *)(r10 - 32) = r2
call %[bpf_cast_to_kern_ctx]
r2 = *(u64 *)(r10 - 32)
r0 = r2;"
As follows:
r2 = 1 /* spill/fill at r10[-32] is removed */
r0 = r1 /* replacement for bpf_cast_to_kern_ctx() */
r0 = r2
exit
Also, attribute used by LLVM implementation of the feature had been
changed from no_caller_saved_registers to bpf_fastcall (see [2]).
This patch-set replaces references to nocsr by references to
bpf_fastcall to keep LLVM and Kernel parts in sync.
[1] no_caller_saved_registers attribute for helper calls
https://lore.kernel.org/bpf/20240722233844.1406874-1-eddyz87@gmail.com/
[2] [BPF] introduce __attribute__((bpf_fastcall))
https://github.com/llvm/llvm-project/pull/105417
Changes v2->v3:
- added a patch fixing arch_mask handling in test_loader,
otherwise newly added tests for the feature were skipped
(a fix for regression introduced by a recent commit);
- fixed warning regarding unused 'params' variable;
- applied stylistical fixes suggested by Yonghong;
- added acks from Yonghong;
Changes v1->v2:
- added two patches replacing all mentions of nocsr by bpf_fastcall
(suggested by Andrii);
- removed KF_NOCSR flag (suggested by Yonghong).
v1: https://lore.kernel.org/bpf/20240812234356.2089263-1-eddyz87@gmail.com/
v2: https://lore.kernel.org/bpf/20240817015140.1039351-1-eddyz87@gmail.com/
====================
Link: https://lore.kernel.org/r/20240822084112.3257995-1-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@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 reStructuredText 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.