Re: [PATCH v6 2/3] powerpc: Move script to check relocations at compile time in scripts/

[Michael Ellerman]

Alexandre Ghiti <alex@xxxxxxxx> 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@xxxxxxxx>
> Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>
> ---
>  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@xxxxxxxxxxxxxx> (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
>
>
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