kpatch-build: fix ppc64le trampoline handling after BPF changes #1477
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joe-lawrence
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Sep 5, 2025
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Code changes look fine. As we discussed off list, we could be more deliberate about detecting one or two NOPs, but since this is only a minor assertion it's not worth the effort.
A few nits with the commit msg:
- I usually use my email alias in this repo: Joe Lawrence joe.lawrence@redhat.com
- As I understand the patchset: [PATCH v7 00/17] powerpc: Core ftrace rework, support for ftrace direct and bpf trampolines:
- We don't need to specify that these were "BPF changes", I think it could just say, "Moving the ftrace stubs out-of-line modified the prologue ..."
- And then regarding vmlinux.arch.o, "... excluded from
instrumentation, since it only contains the out-of-line ftrace stubs for vmlinux. The module loader will create any necessary (livepatch) module ftrace stubs, so we don't care about modifications to this file."
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/packit test --labels integration-pr |
Starting from linux commit eec37961a56a (powerpc64/ftrace: Move ftrace sequence out of line) the kpatch-build fails Extracting new and modified ELF sections create-diff-object: ERROR: fs/proc/cmdline.o: kpatch_create_ftrace_callsite_sections: 3860: cmdline_proc_show: unexpected instruction in patch section of function fs/proc/cmdline.o: changed function: cmdline_proc_show doing "deep find" for parent object ERROR: invalid ancestor arch/powerpc/tools/vmlinux.arch.o for arch/powerpc/tools/vmlinux.arch.o. Check /root/.kpatch/build.log for more details. Moving the ftrace stubs out-of-line modified the prologue on ppc64le and it now uses a single nop instead of two. Update the nop check in create-diff-object.c accordingly. Also add vmlinux.arch.o to the list of objects excluded from instrumentation, since it only contains the out-of-line ftrace stubs for vmlinux. The module loader will create any necessary (livepatch) module ftrace stubs, so we don't care about modifications to this file. Closes: dynup#1470 ("cs-10: ppc64le builds fail") Reported-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Radomir Vrbovsky <rvrbovsk@redhat.com>
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kpatch-build: fix ppc64le trampoline handling after BPF changes
Starting from linux commit eec37961a56a (powerpc64/ftrace: Move
ftrace sequence out of line) the kpatch-build fails
Moving the ftrace stubs out-of-line modified the prologue on ppc64le
and it now uses a single nop instead of two.
Update the nop check in create-diff-object.c accordingly.
Also add vmlinux.arch.o to the list of objects excluded from
instrumentation, since it only contains the out-of-line ftrace stubs
for vmlinux.
The module loader will create any necessary (livepatch) module
ftrace stubs, so we don't care about modifications to this file.
Closes: #1470 ("cs-10: ppc64le builds fail")
Reported-by: Joe Lawrence joe.lawrence@redhat.com
Signed-off-by: Radomir Vrbovsky rvrbovsk@redhat.com