arch/powerpc/tools/unrel_branch_check.sh

   1 #!/bin/bash
   2 # SPDX-License-Identifier: GPL-2.0+
   3 # Copyright © 2016,2020 IBM Corporation
   4 #
   5 # This script checks the unrelocated code of a vmlinux for "suspicious"
   6 # branches to relocated code (head_64.S code).
   7
   8 # Have Kbuild supply the path to objdump and nm so we handle cross compilation.
   9 objdump="$1"
  10 nm="$2"
  11 vmlinux="$3"
  12
  13 kstart=0xc000000000000000
  14
  15 end_intr=0x$($nm -p "$vmlinux" |
  16         sed -E -n '/\s+[[:alpha:]]\s+__end_interrupts\s*$/{s///p;q}')
  17 if [ "$end_intr" = "0x" ]; then
  18         exit 0
  19 fi
  20
  21 # we know that there is a correct branch to
  22 # __start_initialization_multiplatform, so find its address
  23 # so we can exclude it.
  24 sim=0x$($nm -p "$vmlinux" |
  25         sed -E -n '/\s+[[:alpha:]]\s+__start_initialization_multiplatform\s*$/{s///p;q}')
  26
  27 $objdump -D --no-show-raw-insn --start-address="$kstart" --stop-address="$end_intr" "$vmlinux" |
  28 sed -E -n '
  29 # match lines that start with a kernel address
  30 /^c[0-9a-f]*:\s*b/ {
  31         # drop branches via ctr or lr
  32         /\<b.?.?(ct|l)r/d
  33         # cope with some differences between Clang and GNU objdumps
  34         s/\<bt.?\s*[[:digit:]]+,/beq/
  35         s/\<bf.?\s*[[:digit:]]+,/bne/
  36         # tidy up
  37         s/\s0x/ /
  38         s/://
  39         # format for the loop below
  40         s/^(\S+)\s+(\S+)\s+(\S+)\s*(\S*).*$/\1:\2:\3:\4/
  41         # strip out condition registers
  42         s/:cr[0-7],/:/
  43         p
  44 }' | {
  45
  46 all_good=true
  47 while IFS=: read -r from branch to sym; do
  48         case "$to" in
  49         c*)     to="0x$to"
  50                 ;;
  51         .+*)
  52                 to=${to#.+}
  53                 if [ "$branch" = 'b' ]; then
  54                         if (( to >= 0x2000000 )); then
  55                                 to=$(( to - 0x4000000 ))
  56                         fi
  57                 elif (( to >= 0x8000 )); then
  58                         to=$(( to - 0x10000 ))
  59                 fi
  60                 printf -v to '0x%x' $(( "0x$from" + to ))
  61                 ;;
  62         *)      printf 'Unkown branch format\n'
  63                 ;;
  64         esac
  65         if [ "$to" = "$sim" ]; then
  66                 continue
  67         fi
  68         if (( to > end_intr )); then
  69                 if $all_good; then
  70                         printf '%s\n' 'WARNING: Unrelocated relative branches'
  71                         all_good=false
  72                 fi
  73                 printf '%s %s-> %s %s\n' "$from" "$branch" "$to" "$sym"
  74         fi
  75 done
  76
  77 $all_good
  78
  79 }