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Mon, 16 Mar 2026 06:25:29 +0000 (GMT) From: Sathvika Vasireddy To: linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: nathan@kernel.org, masahiroy@kernel.org, kees@kernel.org, naveen@kernel.org, jpoimboe@kernel.org, peterz@infradead.org, npiggin@gmail.com, maddy@linux.ibm.com, segher@kernel.crashing.org, christophe.leroy@csgroup.eu, mingo@kernel.org, mpe@ellerman.id.au, sv@linux.ibm.com, nsc@kernel.org Subject: [RFC PATCH v4 0/6] objtool: Fixup alternate feature relative addresses Date: Mon, 16 Mar 2026 11:52:31 +0530 Message-ID: <20260316062237.30948-1-sv@linux.ibm.com> X-Mailer: git-send-email 2.50.1 Precedence: bulk X-Mailing-List: linux-kbuild@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: nYEJmDpLY7HyH9eAZN9vUpMeD8kg7JyA X-Proofpoint-ORIG-GUID: jDfODcr_XMnMU7nqBxJ61fZD6tbyC3lA X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzE2MDA0NSBTYWx0ZWRfXwu/RuX7imXF3 gAY9kdaV+dIJAhJ3K4s8mLLCPvBAroLN7R4neftSHdntKG5dJ9SQDgn7x8r6XVRT0izkhrUGHsq 8bCRCqw5c0czm89NOIhaeIPcgdSvl3AhXHnnzp3EBwL4PePYTbiezhmlmSK8vOkrC3/O2pR/vGh +CWuWw598wy1lER+ik/VtaxeDuZlMrJRd/KZnVkgOKQLLQyIawXVque9oF0GTWemupLFLLTnYzQ bAGeCDyrY8DPFdmtQkndahhKiaAhRPv8kL7e6F6+sj6Xhdh6rLFRkzWnm6lyBiIeeGr+qPMYPbS w3dg7j/0/MlTbUrSKD2euUpPHaRJWGpTfR0yXbgG/LCaBUVjpJLJhlbAMsFIe6K+bhbgy55/sJo OSODXxrQ2pZEZL9X+8SgP70qoW03P8/LnsJBttLRiKsmC3u3/5lufb92gsw/gjueG1l6CgDLCdi 1mZMnK6Ap//2OM1Pt5g== X-Authority-Analysis: v=2.4 cv=Hf8ZjyE8 c=1 sm=1 tr=0 ts=69b7a262 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=voM4FWlXAAAA:8 a=pGLkceISAAAA:8 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=1UX6Do5GAAAA:8 a=cBShpBCZYLthc8V9hoIA:9 a=IC2XNlieTeVoXbcui8wp:22 a=Et2XPkok5AAZYJIKzHr1:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-16_02,2026-03-13_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 malwarescore=0 lowpriorityscore=0 impostorscore=0 bulkscore=0 suspectscore=0 priorityscore=1501 spamscore=0 adultscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2603160045 This patch series implements build-time fixup of alternate feature relative addresses for powerpc. Previously, Nicholas Piggin proposed a build-time solution using a custom PowerPC tool [1], which provided the foundation for this approach. The current implementation leverages objtool's existing ELF parsing infrastructure to do the same. This patchset applies atop powerpc/merge branch. Links and History: [1] Original PowerPC tool approach: http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20170521010130.13552-1-npiggin@gmail.com/ [2] Initial RFC v1: https://lore.kernel.org/linuxppc-dev/20240422092206.147078-1-sv@linux.ibm.com/T/#t [3] PowerPC instruction decoder borrowed from: https://lore.kernel.org/linuxppc-dev/bfa8364da047d8610a09458a1cd924a0566aedbb.1736955567.git.christophe.leroy@csgroup.eu/#Z31tools:objtool:arch:powerpc:decode.c Testing: Build and Boot tested on ppc64le, ppc64be, and ppc32be configs. Changes in V4: - consolidate emit-relocs remove-section logic for CONFIG_ARCH_VMLINUX_NEEDS_RELOCS and CONFIG_HAVE_OBJTOOL_FTR_FIXUP configs as suggested by Nathan Chancellor. Changes in V3: - Split code into individual patches - Put objtool call into cmd_link_vmlinux - Move HAVE_OBJTOOL_FEATURE_FIXUP from arch/Kconfig to arch/powerpc/Kconfig Changes in V2: - Added implementation support for ppc64 LE, BE, ppc32 BE. Sathvika Vasireddy (6): objtool/powerpc: Add build-time fixup of alternate feature branch targets objtool: Set ELF_F_LAYOUT flag to preserve vmlinux segment layout objtool: Fix "can't find starting instruction" warnings on vmlinux objtool/powerpc: Skip jump destination analysis and unnanotated intra-function call warnings for --ftr-fixup kbuild: Add objtool integration for PowerPC feature fixups powerpc: Enable build-time feature fixup processing by default Sathvika Vasireddy (6): objtool/powerpc: Add build-time fixup of alternate feature branch targets objtool: Set ELF_F_LAYOUT flag to preserve vmlinux segment layout objtool: Fix "can't find starting instruction" warnings on vmlinux objtool/powerpc: Skip jump destination analysis and unnanotated intra-function call warnings for --ftr-fixup kbuild: Add objtool integration for PowerPC feature fixups powerpc: Enable build-time feature fixup processing by default Makefile | 7 + arch/powerpc/Kconfig | 3 + arch/powerpc/Makefile | 5 + arch/powerpc/include/asm/feature-fixups.h | 2 +- arch/powerpc/kernel/vmlinux.lds.S | 8 +- arch/powerpc/lib/feature-fixups.c | 12 - scripts/Makefile.lib | 4 +- scripts/Makefile.vmlinux | 11 +- tools/objtool/arch/powerpc/decode.c | 15 +- tools/objtool/arch/powerpc/special.c | 437 ++++++++++++++++++++++ tools/objtool/builtin-check.c | 2 + tools/objtool/check.c | 42 ++- tools/objtool/elf.c | 4 + tools/objtool/include/objtool/builtin.h | 1 + tools/objtool/include/objtool/special.h | 56 +++ tools/objtool/special.c | 29 ++ 16 files changed, 612 insertions(+), 26 deletions(-) -- 2.43.0