name : unrel_branch_check.sh #!/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 }