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SubjectRe: [PATCHv5 0/4] Salted build ids via ELF notes
Hi.

2018-07-04 8:21 GMT+09:00 Laura Abbott <labbott@redhat.com>:
>
> Hi,
>
> This is v5 of the series to allow unique build ids in the kernel. As a
> reminder of the context:




> ""
> In Fedora, the debug information is packaged separately (foo-debuginfo) and
> can be installed separately. There's been a long standing issue where only one
> version of a debuginfo info package can be installed at a time. Mark Wielaard
> made an effort for Fedora 27 to allow parallel installation of debuginfo (see
> https://fedoraproject.org/wiki/Changes/ParallelInstallableDebuginfo for
> more details)
>
> Part of the requirement to allow this to work is that build ids are
> unique between builds. The existing upstream rpm implementation ensures
> this by re-calculating the build-id using the version and release as a
> seed. This doesn't work 100% for the kernel because of the vDSO which is
> its own binary and doesn't get updated. After poking holes in a few of my
> ideas, there was a discussion with some people from the binutils team about
> adding --build-id-salt to let ld do the calculation debugedit is doing. There
> was a counter proposal made to add in the salt while building. The
> easiest proposal was to add an item in the linker script vs. linking in
> an object since we need the salt to go in every module as well as the
> kernel and vmlinux.
> ""

I think this information is helpful to explain the background
of this work, but the cover letter cannot be committed in git.

Could you add this in 1/4 please?


If I read only the simple log in 1/4,
I would wonder why it is useful...







> v5 uses the approach suggested by Masahiro Yamada which uses the
> existing ELF note macro to more easily add the salt (vs previous
> approaches which tried to adjust via linker section).
>
> If arch maintainers are okay, I'd like acks for this so this can go
> through the kbuild tree.
>
> Thanks,
> Laura
>
> Laura Abbott (4):
> kbuild: Add build salt to the kernel and modules
> x86: Add build salt to the vDSO
> powerpc: Add build salt to the vDSO
> arm64: Add build salt to the vDSO
>
> arch/arm64/kernel/vdso/note.S | 3 +++
> arch/powerpc/kernel/vdso32/note.S | 3 +++
> arch/x86/entry/vdso/vdso-note.S | 3 +++
> arch/x86/entry/vdso/vdso32/note.S | 3 +++
> include/linux/build-salt.h | 20 ++++++++++++++++++++
> init/Kconfig | 9 +++++++++
> init/version.c | 3 +++
> scripts/mod/modpost.c | 3 +++
> 8 files changed, 47 insertions(+)
> create mode 100644 include/linux/build-salt.h
>
> --
> 2.17.1
>
> --
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--
Best Regards
Masahiro Yamada

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