From: Nick Desaulniers <ndesaulniers@google.com>
To: Nathan Chancellor <natechancellor@gmail.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Russell King <linux@armlinux.org.uk>,
Florian Fainelli <f.fainelli@gmail.com>,
Arnd Bergmann <arnd@arndb.de>,
Abbott Liu <liuwenliang@huawei.com>,
Linus Walleij <linus.walleij@linaro.org>,
Jian Cai <jiancai@google.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Mike Rapoport <rppt@linux.ibm.com>,
Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Ard Biesheuvel <ardb@kernel.org>,
Fangrui Song <maskray@google.com>, Dan Rue <dan.rue@linaro.org>,
Mark Brown <broonie@kernel.org>
Subject: Re: [PATCH] kbuild: Always link with '-z norelro'
Date: Wed, 18 Nov 2020 15:05:45 -0800 [thread overview]
Message-ID: <CAKwvOdnauFdUgS0Ww=O-PHrXWhXQEEYd806NUcy8_7MOG0Uo2g@mail.gmail.com> (raw)
In-Reply-To: <CAKwvOdk1ir=D---9xVAxcErJWSGVxK1Mv6AC=TK3RVwNdcvFjw@mail.gmail.com>
On Fri, Nov 13, 2020 at 11:34 AM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> On Thu, Nov 12, 2020 at 10:06 PM Ard Biesheuvel <ardb@kernel.org> wrote:
> >
> > On Fri, 13 Nov 2020 at 01:53, Nathan Chancellor
> > <natechancellor@gmail.com> wrote:
> > >
> > > On Thu, Nov 12, 2020 at 04:44:46PM -0800, Nick Desaulniers wrote:
> > > > On Thu, Nov 12, 2020 at 10:41 AM Nathan Chancellor
> > > > <natechancellor@gmail.com> wrote:
> > > > >
> > > > > Commit 3bbd3db86470 ("arm64: relocatable: fix inconsistencies in linker
> > > > > script and options") added '-z norelro' to the arm64 Makefile when
> > > > > CONFIG_RELOCATABLE was set to help support ld.lld because ld.lld
> > > > > defaults to '-z relro' but the kernel does not use program headers or
> > > > > adhere to the section layout that is required for RELRO to work.
> > > > >
> > > > > Commit 3b92fa7485eb ("arm64: link with -z norelro regardless of
> > > > > CONFIG_RELOCATABLE") unconditionally added it to LDFLAGS_vmlinux because
> > > > > an error occurs with CONFIG_KASAN set even when CONFIG_RELOCATABLE is
> > > > > unset.
> > > > >
> > > > > As it turns out, ARM experiences the same error after CONFIG_KASAN was
> > > > > implemented, meaning that '-z norelro' needs to be added to that
> > > > > Makefile as well (multi_v7_defconfig + CONFIG_KASAN=y + LD=ld.lld):
> > > > >
> > > > > $ make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- LLVM=1 zImage
> > > > > ld.lld: error: section: .exit.data is not contiguous with other relro sections
> > > > >
> > > > > To avoid playing whack-a-mole with different architectures over time,
> > > > > hoist '-z norelro' into the main Makefile. This does not affect ld.bfd
> > > > > because '-z norelro' is the default for it.
Fangrui pointed out off list that this might need an ld-option wrapper
for older versions of GNU binutils. Dan was showing me some build
logs today, and I thought I spotted such warnings about `-z norelro
will be ignored`.
--
Thanks,
~Nick Desaulniers
next prev parent reply other threads:[~2020-11-18 23:06 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-12 18:38 [PATCH] kbuild: Always link with '-z norelro' Nathan Chancellor
2020-11-13 0:44 ` Nick Desaulniers
2020-11-13 0:53 ` Nathan Chancellor
2020-11-13 6:06 ` Ard Biesheuvel
2020-11-13 19:34 ` Nick Desaulniers
2020-11-18 23:05 ` Nick Desaulniers [this message]
2020-11-18 23:06 ` Ard Biesheuvel
2020-11-18 23:24 ` Nick Desaulniers
2020-11-19 19:33 ` Nathan Chancellor
2020-11-16 12:31 ` Catalin Marinas
2020-11-17 21:17 ` Linus Walleij
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