linux-kernel - [PATCH bpf-next v3 0/6] resolve_btfids: Support for BTF modifications

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Message-ID: <20251205223046.4155870-1-ihor.solodrai@linux.dev>
Date: Fri,  5 Dec 2025 14:30:40 -0800
From: Ihor Solodrai <ihor.solodrai@...ux.dev>
To: Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrii Nakryiko <andrii@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Eduard Zingerman <eddyz87@...il.com>,
	Song Liu <song@...nel.org>,
	Yonghong Song <yonghong.song@...ux.dev>,
	John Fastabend <john.fastabend@...il.com>,
	KP Singh <kpsingh@...nel.org>,
	Stanislav Fomichev <sdf@...ichev.me>,
	Hao Luo <haoluo@...gle.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Nicolas Schier <nsc@...nel.org>,
	Tejun Heo <tj@...nel.org>,
	David Vernet <void@...ifault.com>,
	Andrea Righi <arighi@...dia.com>,
	Changwoo Min <changwoo@...lia.com>,
	Shuah Khan <shuah@...nel.org>,
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	Alan Maguire <alan.maguire@...cle.com>,
	Donglin Peng <dolinux.peng@...il.com>
Cc: bpf@...r.kernel.org,
	dwarves@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-kbuild@...r.kernel.org
Subject: [PATCH bpf-next v3 0/6] resolve_btfids: Support for BTF modifications

This series changes resolve_btfids and kernel build scripts to enable
BTF transformations in resolve_btfids. Main motivation for enhancing
resolve_btfids is to reduce dependency of the kernel build on pahole
capabilities [1] and enable BTF features and optimizations [2][3]
particular to the kernel.

Patches #1-#3 in the series are non-functional refactoring in
resolve_btfids.

Patch #4 changes minimum version of pahole required for
CONFIG_DEBUG_INFO_BTF to v1.22

Patch #5 makes a small prep change in selftests/bpf build.

The last patch (#6) makes significant changes in resolve_btfids and
introduces scripts/gen-btf.sh. See implementation details in the patch
description.

Successful CI run: https://github.com/kernel-patches/bpf/actions/runs/19976024062?pr=10438

[1] https://lore.kernel.org/dwarves/ba1650aa-fafd-49a8-bea4-bdddee7c38c9@linux.dev/
[2] https://lore.kernel.org/bpf/20251029190113.3323406-1-ihor.solodrai@linux.dev/
[3] https://lore.kernel.org/bpf/20251119031531.1817099-1-dolinux.peng@gmail.com/

---

v2->v3:
  - add patch #4 bumping minimum pahole version (Andrii, Alan)
  - add patch #5 pre-fixing resolve_btfids test (Donglin)
  - add GEN_BTF var and assemble RESOLVE_BTFIDS_FLAGS in Makefile.btf (Alan)
  - implement --distill_base flag in resolve_btfids, set it depending
    on KBUILD_EXTMOD in Makefile.btf (Eduard)
  - various implementation nits, see the v2 thread for details (Andrii, Eduard)

v2: https://lore.kernel.org/bpf/20251127185242.3954132-1-ihor.solodrai@linux.dev/

v1->v2:
  - gen-btf.sh and other shell script fixes (Donglin)
  - update selftests build (Donglin)
  - generate .BTF.base only when KBUILD_EXTMOD is set (Alan)
  - proper endianness handling for cross-compilation
  - change elf_begin mode from ELF_C_RDWR_MMAP to ELF_C_READ_MMAP_PRIVATE
  - remove compressed_section_fix()
  - nit NULL check in patch #3 (suggested by AI)

v1: https://lore.kernel.org/bpf/20251126012656.3546071-1-ihor.solodrai@linux.dev/

Ihor Solodrai (6):
  resolve_btfids: Rename object btf field to btf_path
  resolve_btfids: Factor out load_btf()
  resolve_btfids: Introduce enum btf_id_kind
  lib/Kconfig.debug: Set the minimum required pahole version to v1.22
  selftests/bpf: Run resolve_btfids only for relevant .test.o objects
  resolve_btfids: change in-place update with raw binary output

 MAINTAINERS                                   |   1 +
 lib/Kconfig.debug                             |  13 +-
 scripts/Makefile.btf                          |  26 +-
 scripts/Makefile.modfinal                     |   5 +-
 scripts/Makefile.vmlinux                      |   2 +-
 scripts/gen-btf.sh                            | 157 ++++++++
 scripts/link-vmlinux.sh                       |  46 +--
 tools/bpf/resolve_btfids/main.c               | 355 ++++++++++++------
 tools/sched_ext/README.md                     |   1 -
 tools/testing/selftests/bpf/.gitignore        |   3 +
 tools/testing/selftests/bpf/Makefile          |  11 +-
 .../selftests/bpf/prog_tests/resolve_btfids.c |   4 +-
 12 files changed, 434 insertions(+), 190 deletions(-)
 create mode 100755 scripts/gen-btf.sh

-- 
2.52.0