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Alexis Lothoré (eBPF Foundation) dc704d0cfa bpf, arm64: remove structs on stack constraint 
While introducing support for 9+ arguments for tracing programs on
ARM64, commit 9014cf56f1 ("bpf, arm64: Support up to 12 function
arguments") has also introduced a constraint preventing BPF trampolines
from being generated if the target function consumes a struct argument
passed on stack, because of uncertainties around the exact struct
location: if the struct has been marked as packed or with a custom
alignment, this info is not reflected in BTF data, and so generated
tracing trampolines could read the target function arguments at wrong
offsets.

This issue is not specific to ARM64: there has been an attempt (see [1])
to bring the same constraint to other architectures JIT compilers. But
discussions following this attempt led to the move of this constraint
out of the kernel (see [2]): instead of preventing the kernel from
generating trampolines for those functions consuming structs on stack,
it is simpler to just make sure that those functions with uncertain
struct arguments location are not encoded in BTF information, and so
that one can not even attempt to attach a tracing program to such
function. The task is then deferred to pahole (see [3]).

Now that the constraint is handled by pahole, remove it from the arm64
JIT compiler to keep it simple.

[1] https://lore.kernel.org/bpf/20250613-deny_trampoline_structs_on_stack-v1-0-5be9211768c3@bootlin.com/
[2] https://lore.kernel.org/bpf/CAADnVQ+sj9XhscN9PdmTzjVa7Eif21noAUH3y1K6x5bWcL-5pg@mail.gmail.com/
[3] https://lore.kernel.org/bpf/20250707-btf_skip_structs_on_stack-v3-0-29569e086c12@bootlin.com/

Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
Link: https://lore.kernel.org/r/20250709-arm64_relax_jit_comp-v1-1-3850fe189092@bootlin.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-07-16 18:28:30 -07:00
arch bpf, arm64: remove structs on stack constraint 2025-07-16 18:28:30 -07:00
block block-6.16-20250614 2025-06-14 09:25:22 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: ahash - Fix infinite recursion in ahash_def_finup 2025-06-18 17:02:02 +08:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf after rc3 2025-06-26 09:49:39 -07:00
drivers netkit: Remove location field in netkit_link 2025-07-11 11:01:09 -07:00
fs Merge branch 'vfs-6.17.bpf' of https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs 2025-06-26 19:01:04 -07:00
include bpf: Remove attach_type in bpf_tracing_link 2025-07-11 11:01:08 -07:00
init init: fix build warnings about export.h 2025-06-11 22:42:36 -07:00
io_uring io_uring-6.16-20250621 2025-06-21 08:40:45 -07:00
ipc - The 3 patch series "hung_task: extend blocking task stacktrace dump to 2025-05-31 19:12:53 -07:00
kernel bpf: Remove attach_type in bpf_tracing_link 2025-07-11 11:01:08 -07:00
lib 20 hotfixes. 7 are cc:stable and the remainder address post-6.15 issues 2025-06-23 09:20:39 -07:00
LICENSES LICENSES: add CC0-1.0 license text 2025-05-21 14:54:17 +02:00
mm 20 hotfixes. 7 are cc:stable and the remainder address post-6.15 issues 2025-06-23 09:20:39 -07:00
net bpf: Remove attach_type in sockmap_link 2025-07-11 10:51:55 -07:00
rust Driver core fixes for 6.16-rc3 2025-06-18 14:31:16 -07:00
samples - The 3 patch series "hung_task: extend blocking task stacktrace dump to 2025-05-31 19:12:53 -07:00
scripts gendwarfksyms: Fix structure type overrides 2025-06-16 00:49:48 +09:00
security selinux: change security_compute_sid to return the ssid or tsid on match 2025-06-19 16:13:16 -04:00
sound ALSA: hda/realtek: Enable headset Mic on Positivo P15X 2025-06-20 10:05:46 +02:00
tools selftests/bpf: Fix build error due to certain uninitialized variables 2025-07-15 14:38:58 -07:00
usr usr/include: openrisc: don't HDRTEST bpf_perf_event.h 2025-05-12 15:03:17 +09:00
virt Merge branch 'kvm-lockdep-common' into HEAD 2025-05-28 06:29:17 -04:00
.clang-format Linux 6.15-rc5 2025-05-06 16:39:25 +10:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: ignore Python compiled bytecode 2025-04-24 10:12:46 -06:00
.mailmap Including fixes from wireless. The ath12k fix to avoid FW crashes 2025-06-19 10:21:32 -07:00
.pylintrc docs: add a .pylintrc file with sys path for docs scripts 2025-04-09 12:10:33 -06:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS CREDITS: Add entry for Shannon Nelson 2025-06-21 07:34:28 -07:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS 20 hotfixes. 7 are cc:stable and the remainder address post-6.15 issues 2025-06-23 09:20:39 -07:00
Makefile Linux 6.16-rc3 2025-06-22 13:30:08 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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 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.