^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) #! /bin/bash
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) # SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) # (c) 2015, Quentin Casasnovas <quentin.casasnovas@oracle.com>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) obj=$1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) file ${obj} | grep -q ELF || (echo "${obj} is not and ELF file." 1>&2 ; exit 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) # Bail out early if there isn't an __ex_table section in this object file.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) objdump -hj __ex_table ${obj} 2> /dev/null > /dev/null
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) [ $? -ne 0 ] && exit 0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) white_list=.text,.fixup
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) suspicious_relocs=$(objdump -rj __ex_table ${obj} | tail -n +6 |
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) grep -v $(eval echo -e{${white_list}}) | awk '{print $3}')
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) # No suspicious relocs in __ex_table, jobs a good'un
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) [ -z "${suspicious_relocs}" ] && exit 0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) # After this point, something is seriously wrong since we just found out we
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) # have some relocations in __ex_table which point to sections which aren't
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) # white listed. If you're adding a new section in the Linux kernel, and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) # you're expecting this section to contain code which can fault (i.e. the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) # __ex_table relocation to your new section is expected), simply add your
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) # new section to the white_list variable above. If not, you're probably
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) # doing something wrong and the rest of this code is just trying to print
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) # you more information about it.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) function find_section_offset_from_symbol()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) eval $(objdump -t ${obj} | grep ${1} | sed 's/\([0-9a-f]\+\) .\{7\} \([^ \t]\+\).*/section="\2"; section_offset="0x\1" /')
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) # addr2line takes addresses in hexadecimal...
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) section_offset=$(printf "0x%016x" $(( ${section_offset} + $2 )) )
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) function find_symbol_and_offset_from_reloc()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) # Extract symbol and offset from the objdump output
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) eval $(echo $reloc | sed 's/\([^+]\+\)+\?\(0x[0-9a-f]\+\)\?/symbol="\1"; symbol_offset="\2"/')
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) # When the relocation points to the begining of a symbol or section, it
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) # won't print the offset since it is zero.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) if [ -z "${symbol_offset}" ]; then
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) symbol_offset=0x0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) fi
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) function find_alt_replacement_target()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) # The target of the .altinstr_replacement is the relocation just before
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) # the .altinstr_replacement one.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) eval $(objdump -rj .altinstructions ${obj} | grep -B1 "${section}+${section_offset}" | head -n1 | awk '{print $3}' |
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) sed 's/\([^+]\+\)+\(0x[0-9a-f]\+\)/alt_target_section="\1"; alt_target_offset="\2"/')
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) function handle_alt_replacement_reloc()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) # This will define alt_target_section and alt_target_section_offset
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) find_alt_replacement_target ${section} ${section_offset}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) echo "Error: found a reference to .altinstr_replacement in __ex_table:"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) addr2line -fip -j ${alt_target_section} -e ${obj} ${alt_target_offset} | awk '{print "\t" $0}'
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) error=true
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) function is_executable_section()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) objdump -hwj ${section} ${obj} | grep -q CODE
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) return $?
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) function handle_suspicious_generic_reloc()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) if is_executable_section ${section}; then
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) # We've got a relocation to a non white listed _executable_
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) # section, print a warning so the developper adds the section to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) # the white list or fix his code. We try to pretty-print the file
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) # and line number where that relocation was added.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) echo "Warning: found a reference to section \"${section}\" in __ex_table:"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) addr2line -fip -j ${section} -e ${obj} ${section_offset} | awk '{print "\t" $0}'
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) # Something is definitively wrong here since we've got a relocation
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) # to a non-executable section, there's no way this would ever be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) # running in the kernel.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89) echo "Error: found a reference to non-executable section \"${section}\" in __ex_table at offset ${section_offset}"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) error=true
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) fi
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) function handle_suspicious_reloc()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) case "${section}" in
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) ".altinstr_replacement")
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) handle_alt_replacement_reloc ${section} ${section_offset}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) ;;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) *)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) handle_suspicious_generic_reloc ${section} ${section_offset}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) ;;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) esac
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) function diagnose()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) for reloc in ${suspicious_relocs}; do
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) # Let's find out where the target of the relocation in __ex_table
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) # is, this will define ${symbol} and ${symbol_offset}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) find_symbol_and_offset_from_reloc ${reloc}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) # When there's a global symbol at the place of the relocation,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) # objdump will use it instead of giving us a section+offset, so
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) # let's find out which section is this symbol in and the total
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) # offset withing that section.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) find_section_offset_from_symbol ${symbol} ${symbol_offset}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) # In this case objdump was presenting us with a reloc to a symbol
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) # rather than a section. Now that we've got the actual section,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) # we can skip it if it's in the white_list.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) if [ -z "$( echo $section | grep -v $(eval echo -e{${white_list}}))" ]; then
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) fi
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) # Will either print a warning if the relocation happens to be in a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) # section we do not know but has executable bit set, or error out.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) handle_suspicious_reloc
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) done
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) function check_debug_info() {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) objdump -hj .debug_info ${obj} 2> /dev/null > /dev/null ||
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) echo -e "${obj} does not contain debug information, the addr2line output will be limited.\n" \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) "Recompile ${obj} with CONFIG_DEBUG_INFO to get a more useful output."
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) check_debug_info
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) diagnose
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) if [ "${error}" ]; then
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) exit 1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) fi
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) exit 0
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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