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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Tue, 27 Oct 2020 11:20:14 +0100
Message-ID: <CAMuHMdVkLXmJEiV-uwOqKnfGQZX65tMFMTjs0O8q5BJsAhCGzg@mail.gmail.com>
Subject: Re: [PATCH v6 13/29] arm64/build: Assert for unwanted sections
To:     Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc:     Ard Biesheuvel <ardb@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Linux-Arch <linux-arch@vger.kernel.org>,
        linux-efi <linux-efi@vger.kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Masahiro Yamada <masahiroy@kernel.org>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Russell King <linux@armlinux.org.uk>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        Arvind Sankar <nivedita@alum.mit.edu>,
        Ingo Molnar <mingo@redhat.com>,
        James Morse <james.morse@arm.com>,
        Nathan Chancellor <natechancellor@gmail.com>,
        Borislav Petkov <bp@suse.de>,
        Peter Collingbourne <pcc@google.com>,
        Ingo Molnar <mingo@kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>
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Hi Jean-Philippe,

On Tue, Oct 27, 2020 at 11:09 AM Jean-Philippe Brucker
<jean-philippe@linaro.org> wrote:
> On Mon, Oct 26, 2020 at 06:38:46PM +0100, Ard Biesheuvel wrote:
> > > > > Note that even on plain be2881824ae9eb92, I get:
> > > > >
> > > > >     aarch64-linux-gnu-ld: Unexpected GOT/PLT entries detected!
> > > > >     aarch64-linux-gnu-ld: Unexpected run-time procedure linkages detected!
> > > > >
> > > > > The parent commit obviously doesn't show that (but probably still has
> > > > > the problem).
> > >
> > > Reverting both
> > > b3e5d80d0c48c0cc ("arm64/build: Warn on orphan section placement")
> > > be2881824ae9eb92 ("arm64/build: Assert for unwanted sections")
> > > seems to solve my problems, without any ill effects?
> > >
> >
> > I cannot reproduce the issue here with my distro GCC+binutils (Debian 8.3.0)
>
> I have the same problem with one of my debug configs and Linux v5.10-rc1,
> and can reproduce with the Debian 8.3.0 toolchain, by using the arm64
> defconfig and disabling CONFIG_MODULES:
>
> ld -EL -maarch64elf --no-undefined -X -z norelro -shared -Bsymbolic -z notext --no-apply-dynamic-relocs --fix-cortex-a53-843419 --orphan-handling=warn --build-id=sha1 --strip-debug -o .tmp_vmlinux.kallsyms1 -T ./arch/arm64/kernel/vmlinux.lds --whole-archive arch/arm64/kernel/head.o init/built-in.a usr/built-in.a arch/arm64/built-in.a kernel/built-in.a certs/built-in.a mm/built-in.a fs/built-in.a ipc/built-in.a security/built-in.a crypto/built-in.a block/built-in.a arch/arm64/lib/built-in.a lib/built-in.a drivers/built-in.a sound/built-in.a net/built-in.a virt/built-in.a --no-whole-archive --start-group arch/arm64/lib/lib.a lib/lib.a ./drivers/firmware/efi/libstub/lib.a --end-group
> ld: Unexpected GOT/PLT entries detected!
> ld: Unexpected run-time procedure linkages detected!
>
> Adding -fno-pie to this command doesn't fix the problem.
>
> Note that when cross-building with a GCC 10.2 and binutils 2.35.1 I also
> get several "aarch64-linux-gnu-ld: warning: -z norelro ignored" in
> addition to the error, but I don't get that warning with the 8.3.0
> toolchain.

Thanks, my config (renesas_defconfig) also had CONFIG_MODULES disabled.
Enabling that fixes the link error due to unexpected entries, but the
.eh_frame orphan section warning is still there.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds