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