linux/linux-5.18.11/arch/powerpc/tools/unrel_branch_check.sh

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#!/bin/bash
# SPDX-License-Identifier: GPL-2.0+
# Copyright © 2016,2020 IBM Corporation
#
# This script checks the unrelocated code of a vmlinux for "suspicious"
# branches to relocated code (head_64.S code).
# Have Kbuild supply the path to objdump and nm so we handle cross compilation.
objdump="$1"
nm="$2"
vmlinux="$3"
kstart=0xc000000000000000
end_intr=0x$($nm -p "$vmlinux" |
sed -E -n '/\s+[[:alpha:]]\s+__end_interrupts\s*$/{s///p;q}')
if [ "$end_intr" = "0x" ]; then
exit 0
fi
# we know that there is a correct branch to
# __start_initialization_multiplatform, so find its address
# so we can exclude it.
sim=0x$($nm -p "$vmlinux" |
sed -E -n '/\s+[[:alpha:]]\s+__start_initialization_multiplatform\s*$/{s///p;q}')
$objdump -D --no-show-raw-insn --start-address="$kstart" --stop-address="$end_intr" "$vmlinux" |
sed -E -n '
# match lines that start with a kernel address
/^c[0-9a-f]*:\s*b/ {
# drop branches via ctr or lr
/\<b.?.?(ct|l)r/d
# cope with some differences between Clang and GNU objdumps
s/\<bt.?\s*[[:digit:]]+,/beq/
s/\<bf.?\s*[[:digit:]]+,/bne/
# tidy up
s/\s0x/ /
s/://
# format for the loop below
s/^(\S+)\s+(\S+)\s+(\S+)\s*(\S*).*$/\1:\2:\3:\4/
# strip out condition registers
s/:cr[0-7],/:/
p
}' | {
all_good=true
while IFS=: read -r from branch to sym; do
case "$to" in
c*) to="0x$to"
;;
.+*)
to=${to#.+}
if [ "$branch" = 'b' ]; then
if (( to >= 0x2000000 )); then
to=$(( to - 0x4000000 ))
fi
elif (( to >= 0x8000 )); then
to=$(( to - 0x10000 ))
fi
printf -v to '0x%x' $(( "0x$from" + to ))
;;
*) printf 'Unkown branch format\n'
;;
esac
if [ "$to" = "$sim" ]; then
continue
fi
if (( to > end_intr )); then
if $all_good; then
printf '%s\n' 'WARNING: Unrelocated relative branches'
all_good=false
fi
printf '%s %s-> %s %s\n' "$from" "$branch" "$to" "$sym"
fi
done
$all_good
}