From: Michael Ellerman <mpe@ellerman.id.au>
To: Alexandre Ghiti <alex@ghiti.fr>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
linux-riscv@lists.infradead.org
Cc: Alexandre Ghiti <alex@ghiti.fr>, Anup Patel <anup@brainfault.org>
Subject: Re: [PATCH v6 2/3] powerpc: Move script to check relocations at compile time in scripts/
Date: Wed, 19 May 2021 11:09:39 +1000 [thread overview]
Message-ID: <877djvjzqk.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20210518101252.1484465-3-alex@ghiti.fr>
Alexandre Ghiti <alex@ghiti.fr> writes:
> Relocating kernel at runtime is done very early in the boot process, so
> it is not convenient to check for relocations there and react in case a
> relocation was not expected.
>
> Powerpc architecture has a script that allows to check at compile time
> for such unexpected relocations: extract the common logic to scripts/
> so that other architectures can take advantage of it.
>
> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
> Reviewed-by: Anup Patel <anup@brainfault.org>
> ---
> arch/powerpc/tools/relocs_check.sh | 18 ++----------------
> scripts/relocs_check.sh | 20 ++++++++++++++++++++
> 2 files changed, 22 insertions(+), 16 deletions(-)
> create mode 100755 scripts/relocs_check.sh
I'm not sure that script is really big/complicated enough to warrant
sharing vs just copying, but I don't mind either.
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
cheers
> diff --git a/arch/powerpc/tools/relocs_check.sh b/arch/powerpc/tools/relocs_check.sh
> index 014e00e74d2b..e367895941ae 100755
> --- a/arch/powerpc/tools/relocs_check.sh
> +++ b/arch/powerpc/tools/relocs_check.sh
> @@ -15,21 +15,8 @@ if [ $# -lt 3 ]; then
> exit 1
> fi
>
> -# Have Kbuild supply the path to objdump and nm so we handle cross compilation.
> -objdump="$1"
> -nm="$2"
> -vmlinux="$3"
> -
> -# Remove from the bad relocations those that match an undefined weak symbol
> -# which will result in an absolute relocation to 0.
> -# Weak unresolved symbols are of that form in nm output:
> -# " w _binary__btf_vmlinux_bin_end"
> -undef_weak_symbols=$($nm "$vmlinux" | awk '$1 ~ /w/ { print $2 }')
> -
> bad_relocs=$(
> -$objdump -R "$vmlinux" |
> - # Only look at relocation lines.
> - grep -E '\<R_' |
> +${srctree}/scripts/relocs_check.sh "$@" |
> # These relocations are okay
> # On PPC64:
> # R_PPC64_RELATIVE, R_PPC64_NONE
> @@ -43,8 +30,7 @@ R_PPC_ADDR16_LO
> R_PPC_ADDR16_HI
> R_PPC_ADDR16_HA
> R_PPC_RELATIVE
> -R_PPC_NONE' |
> - ([ "$undef_weak_symbols" ] && grep -F -w -v "$undef_weak_symbols" || cat)
> +R_PPC_NONE'
> )
>
> if [ -z "$bad_relocs" ]; then
> diff --git a/scripts/relocs_check.sh b/scripts/relocs_check.sh
> new file mode 100755
> index 000000000000..137c660499f3
> --- /dev/null
> +++ b/scripts/relocs_check.sh
> @@ -0,0 +1,20 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0-or-later
> +
> +# Get a list of all the relocations, remove from it the relocations
> +# that are known to be legitimate and return this list to arch specific
> +# script that will look for suspicious relocations.
> +
> +objdump="$1"
> +nm="$2"
> +vmlinux="$3"
> +
> +# Remove from the possible bad relocations those that match an undefined
> +# weak symbol which will result in an absolute relocation to 0.
> +# Weak unresolved symbols are of that form in nm output:
> +# " w _binary__btf_vmlinux_bin_end"
> +undef_weak_symbols=$($nm "$vmlinux" | awk '$1 ~ /w/ { print $2 }')
> +
> +$objdump -R "$vmlinux" |
> + grep -E '\<R_' |
> + ([ "$undef_weak_symbols" ] && grep -F -w -v "$undef_weak_symbols" || cat)
> --
> 2.30.2
>
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
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next prev parent reply other threads:[~2021-05-19 1:10 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-18 10:12 [PATCH v6 0/3] Introduce 64b relocatable kernel Alexandre Ghiti
2021-05-18 10:12 ` [PATCH v6 1/3] riscv: Introduce CONFIG_RELOCATABLE Alexandre Ghiti
2021-05-18 10:12 ` [PATCH v6 2/3] powerpc: Move script to check relocations at compile time in scripts/ Alexandre Ghiti
2021-05-19 1:09 ` Michael Ellerman [this message]
2021-05-18 10:12 ` [PATCH v6 3/3] riscv: Check relocations at compile time Alexandre Ghiti
2021-06-17 13:33 ` [PATCH v6 0/3] Introduce 64b relocatable kernel Alex Ghiti
2021-07-01 5:42 ` Palmer Dabbelt
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