From: Nathan Chancellor <natechancellor@gmail.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Masahiro Yamada <masahiroy@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
Kees Cook <keescook@chromium.org>,
Russell King <linux@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, Nick Desaulniers <ndesaulniers@google.com>,
Arvind Sankar <nivedita@alum.mit.edu>,
linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org,
clang-built-linux@googlegroups.com
Subject: Re: [PATCH 1/2] kbuild: Hoist '--orphan-handling' into Kconfig
Date: Tue, 17 Nov 2020 09:22:23 -0700 [thread overview]
Message-ID: <20201117162223.GA1428250@ubuntu-m3-large-x86> (raw)
In-Reply-To: <87tuto2qke.fsf@mpe.ellerman.id.au>
On Tue, Nov 17, 2020 at 10:03:29PM +1100, Michael Ellerman wrote:
> Nathan Chancellor <natechancellor@gmail.com> writes:
> > Currently, '--orphan-handling=warn' is spread out across four different
> > architectures in their respective Makefiles, which makes it a little
> > unruly to deal with in case it needs to be disabled for a specific
> > linker version (in this case, ld.lld 10.0.1).
> >
> > To make it easier to control this, hoist this warning into Kconfig and
> > the main Makefile so that disabling it is simpler, as the warning will
> > only be enabled in a couple places (main Makefile and a couple of
> > compressed boot folders that blow away LDFLAGS_vmlinx) and making it
> > conditional is easier due to Kconfig syntax. One small additional
> > benefit of this is saving a call to ld-option on incremental builds
> > because we will have already evaluated it for CONFIG_LD_ORPHAN_WARN.
> >
> > To keep the list of supported architectures the same, introduce
> > CONFIG_ARCH_WANT_LD_ORPHAN_WARN, which an architecture can select to
> > gain this automatically after all of the sections are specified and size
> > asserted. A special thanks to Kees Cook for the help text on this
> > config.
> >
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1187
> > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> > ---
> > Makefile | 6 ++++++
> > arch/Kconfig | 9 +++++++++
> > arch/arm/Kconfig | 1 +
> > arch/arm/Makefile | 4 ----
> > arch/arm/boot/compressed/Makefile | 4 +++-
> > arch/arm64/Kconfig | 1 +
> > arch/arm64/Makefile | 4 ----
> > arch/powerpc/Kconfig | 1 +
> > arch/powerpc/Makefile | 1 -
>
> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
>
>
> > arch/x86/Kconfig | 1 +
> > arch/x86/Makefile | 3 ---
> > arch/x86/boot/compressed/Makefile | 4 +++-
> > init/Kconfig | 3 +++
> > 13 files changed, 28 insertions(+), 14 deletions(-)
> >
> > diff --git a/Makefile b/Makefile
> > index 008aba5f1a20..c443afd61886 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -984,6 +984,12 @@ ifeq ($(CONFIG_RELR),y)
> > LDFLAGS_vmlinux += --pack-dyn-relocs=relr
> > endif
> >
> > +# We never want expected sections to be placed heuristically by the
> > +# linker. All sections should be explicitly named in the linker script.
> > +ifeq ($(CONFIG_LD_ORPHAN_WARN),y)
> > +LDFLAGS_vmlinux += --orphan-handling=warn
> > +endif
>
> This is a nit, but you can use ifdef with bool CONFIG symbols in
> Makefiles, which reads a bit nicer, eg:
>
> ifdef CONFIG_LD_ORPHAN_WARN
> LDFLAGS_vmlinux += --orphan-handling=warn
> endif
That is indeed cleaner, I did not realize I could do that as long as the
config was a boolean. I will use that in v2, which I will send along
within the next few days to give Masahiro some time to comment.
Cheers,
Nathan
next prev parent reply other threads:[~2020-11-17 16:22 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-13 19:55 [PATCH 1/2] kbuild: Hoist '--orphan-handling' into Kconfig Nathan Chancellor
2020-11-13 19:55 ` [PATCH 2/2] kbuild: Disable CONFIG_LD_ORPHAN_WARN for ld.lld 10.0.1 Nathan Chancellor
2020-11-17 19:41 ` Nick Desaulniers
2020-11-18 3:12 ` Nathan Chancellor
2020-11-17 21:51 ` Kees Cook
2020-11-18 3:12 ` Nathan Chancellor
2020-11-17 1:41 ` [PATCH 1/2] kbuild: Hoist '--orphan-handling' into Kconfig Nick Desaulniers
2020-11-17 1:54 ` Nathan Chancellor
2020-11-17 19:26 ` Nick Desaulniers
2020-11-17 11:03 ` Michael Ellerman
2020-11-17 16:22 ` Nathan Chancellor [this message]
2020-11-17 21:52 ` Kees Cook
2020-11-19 20:46 ` [PATCH v2 " Nathan Chancellor
2020-11-21 0:08 ` Kees Cook
2020-12-01 13:28 ` Masahiro Yamada
2020-11-19 20:46 ` [PATCH v2 2/2] kbuild: Disable CONFIG_LD_ORPHAN_WARN for ld.lld 10.0.1 Nathan Chancellor
2020-11-19 21:13 ` Nick Desaulniers
2020-11-24 22:22 ` Kees Cook
2020-12-01 13:31 ` Masahiro Yamada
2020-12-01 20:56 ` Kees Cook
2020-12-02 2:37 ` Masahiro Yamada
2020-12-02 18:56 ` Kees Cook
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