CasperSecurity
#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
#
# link vmlinux
#
# vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_OBJS) and
# $(KBUILD_VMLINUX_LIBS). Most are built-in.a files from top-level directories
# in the kernel tree, others are specified in arch/$(ARCH)/Makefile.
# $(KBUILD_VMLINUX_LIBS) are archives which are linked conditionally
# (not within --whole-archive), and do not require symbol indexes added.
#
# vmlinux
# ^
# |
# +--< $(KBUILD_VMLINUX_OBJS)
# | +--< init/built-in.a drivers/built-in.a mm/built-in.a + more
# |
# +--< $(KBUILD_VMLINUX_LIBS)
# | +--< lib/lib.a + more
# |
# +-< ${kallsymso} (see description in KALLSYMS section)
#
# vmlinux version (uname -v) cannot be updated during normal
# descending-into-subdirs phase since we do not yet know if we need to
# update vmlinux.
# Therefore this step is delayed until just before final link of vmlinux.
#
# System.map is generated to document addresses of all kernel symbols
# Error out on error
set -e
LD="$1"
KBUILD_LDFLAGS="$2"
LDFLAGS_vmlinux="$3"
# Nice output in kbuild format
# Will be supressed by "make -s"
info()
{
printf " %-7s %s\n" "${1}" "${2}"
}
# Generate a linker script to ensure correct ordering of initcalls.
gen_initcalls()
{
info GEN .tmp_initcalls.lds
${PYTHON} ${srctree}/scripts/jobserver-exec \
${PERL} ${srctree}/scripts/generate_initcall_order.pl \
${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS} \
> .tmp_initcalls.lds
}
# If CONFIG_LTO_CLANG is selected, collect generated symbol versions into
# .tmp_symversions.lds
gen_symversions()
{
info GEN .tmp_symversions.lds
rm -f .tmp_symversions.lds
for o in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do
if [ -f ${o}.symversions ]; then
cat ${o}.symversions >> .tmp_symversions.lds
fi
done
}
# Link of vmlinux.o used for section mismatch analysis
# ${1} output file
modpost_link()
{
local objects
local lds=""
objects="--whole-archive \
${KBUILD_VMLINUX_OBJS} \
--no-whole-archive \
--start-group \
${KBUILD_VMLINUX_LIBS} \
--end-group"
if [ -n "${CONFIG_LTO_CLANG}" ]; then
gen_initcalls
lds="-T .tmp_initcalls.lds"
if [ -n "${CONFIG_MODVERSIONS}" ]; then
gen_symversions
lds="${lds} -T .tmp_symversions.lds"
fi
# This might take a while, so indicate that we're doing
# an LTO link
info LTO ${1}
else
info LD ${1}
fi
${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects}
}
objtool_link()
{
local objtoolcmd;
local objtoolopt;
if [ "${CONFIG_LTO_CLANG} ${CONFIG_STACK_VALIDATION}" = "y y" ]; then
# Don't perform vmlinux validation unless explicitly requested,
# but run objtool on vmlinux.o now that we have an object file.
if [ -n "${CONFIG_UNWINDER_ORC}" ]; then
objtoolcmd="orc generate"
fi
objtoolopt="${objtoolopt} --duplicate"
if [ -n "${CONFIG_FTRACE_MCOUNT_USE_OBJTOOL}" ]; then
objtoolopt="${objtoolopt} --mcount"
fi
fi
if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then
objtoolopt="${objtoolopt} --noinstr"
if is_enabled CONFIG_CPU_UNRET_ENTRY; then
objtoolopt="${objtoolopt} --unret"
fi
fi
if [ -n "${objtoolopt}" ]; then
if [ -z "${objtoolcmd}" ]; then
objtoolcmd="check"
fi
objtoolopt="${objtoolopt} --vmlinux"
if [ -z "${CONFIG_FRAME_POINTER}" ]; then
objtoolopt="${objtoolopt} --no-fp"
fi
if [ -n "${CONFIG_GCOV_KERNEL}" ] || [ -n "${CONFIG_LTO_CLANG}" ]; then
objtoolopt="${objtoolopt} --no-unreachable"
fi
if [ -n "${CONFIG_RETPOLINE}" ]; then
objtoolopt="${objtoolopt} --retpoline"
fi
if [ -n "${CONFIG_X86_SMAP}" ]; then
objtoolopt="${objtoolopt} --uaccess"
fi
if [ -n "${CONFIG_SLS}" ]; then
objtoolopt="${objtoolopt} --sls"
fi
info OBJTOOL ${1}
tools/objtool/objtool ${objtoolcmd} ${objtoolopt} ${1}
fi
}
# Link of vmlinux
# ${1} - output file
# ${2}, ${3}, ... - optional extra .o files
vmlinux_link()
{
local output=${1}
local objs
local libs
local ld
local ldflags
local ldlibs
info LD ${output}
# skip output file argument
shift
if [ -n "${CONFIG_LTO_CLANG}" ]; then
# Use vmlinux.o instead of performing the slow LTO link again.
objs=vmlinux.o
libs=
else
objs="${KBUILD_VMLINUX_OBJS}"
libs="${KBUILD_VMLINUX_LIBS}"
fi
if [ "${SRCARCH}" = "um" ]; then
wl=-Wl,
ld="${CC}"
ldflags="${CFLAGS_vmlinux}"
ldlibs="-lutil -lrt -lpthread"
else
wl=
ld="${LD}"
ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}"
ldlibs=
fi
ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
# The kallsyms linking does not need debug symbols included.
if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
ldflags="${ldflags} ${wl}--strip-debug"
fi
if [ -n "${CONFIG_VMLINUX_MAP}" ]; then
ldflags="${ldflags} ${wl}-Map=${output}.map"
fi
${ld} ${ldflags} -o ${output} \
${wl}--whole-archive ${objs} ${wl}--no-whole-archive \
${wl}--start-group ${libs} ${wl}--end-group \
$@ ${ldlibs}
}
# generate .BTF typeinfo from DWARF debuginfo
# ${1} - vmlinux image
# ${2} - file to dump raw BTF data into
gen_btf()
{
local pahole_ver
if ! [ -x "$(command -v ${PAHOLE})" ]; then
echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
return 1
fi
pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
if [ "${pahole_ver}" -lt "116" ]; then
echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
return 1
fi
vmlinux_link ${1}
info "BTF" ${2}
LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}
# Create ${2} which contains just .BTF section but no symbols. Add
# SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
# deletes all symbols including __start_BTF and __stop_BTF, which will
# be redefined in the linker script. Add 2>/dev/null to suppress GNU
# objcopy warnings: "empty loadable segment detected at ..."
${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
--strip-all ${1} ${2} 2>/dev/null
# Change e_type to ET_REL so that it can be used to link final vmlinux.
# GNU ld 2.35+ and lld do not allow an ET_EXEC input.
if [ -n "${CONFIG_CPU_BIG_ENDIAN}" ]; then
et_rel='\0\1'
else
et_rel='\1\0'
fi
printf "${et_rel}" | dd of=${2} conv=notrunc bs=1 seek=16 status=none
}
# Create ${2} .S file with all symbols from the ${1} object file
kallsyms()
{
local kallsymopt;
if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
kallsymopt="${kallsymopt} --all-symbols"
fi
if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
kallsymopt="${kallsymopt} --absolute-percpu"
fi
if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
kallsymopt="${kallsymopt} --base-relative"
fi
info KSYMS ${2}
${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2}
}
# Perform one step in kallsyms generation, including temporary linking of
# vmlinux.
kallsyms_step()
{
kallsymso_prev=${kallsymso}
kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
kallsymso=${kallsyms_vmlinux}.o
kallsyms_S=${kallsyms_vmlinux}.S
vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
info AS ${kallsymso}
${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
-c -o ${kallsymso} ${kallsyms_S}
}
# Create map file with all symbols from ${1}
# See mksymap for additional details
mksysmap()
{
${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
}
sorttable()
{
${objtree}/scripts/sorttable ${1}
}
# Delete output files in case of error
cleanup()
{
rm -f .btf.*
rm -f .tmp_System.map
rm -f .tmp_initcalls.lds
rm -f .tmp_symversions.lds
rm -f .tmp_vmlinux*
rm -f System.map
rm -f vmlinux
rm -f vmlinux.map
rm -f vmlinux.o
rm -f .vmlinux.d
}
# Use "make V=1" to debug this script
case "${KBUILD_VERBOSE}" in
*1*)
set -x
;;
esac
if [ "$1" = "clean" ]; then
cleanup
exit 0
fi
# We need access to CONFIG_ symbols
. include/config/auto.conf
# Update version
info GEN .version
if [ -r .version ]; then
VERSION=$(expr 0$(cat .version) + 1)
echo $VERSION > .version
else
rm -f .version
echo 1 > .version
fi;
# final build of init/
${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
#link vmlinux.o
modpost_link vmlinux.o
objtool_link vmlinux.o
# modpost vmlinux.o to check for section mismatches
${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
info MODINFO modules.builtin.modinfo
${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
info GEN modules.builtin
# The second line aids cases where multiple modules share the same object.
tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
btf_vmlinux_bin_o=""
if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
btf_vmlinux_bin_o=.btf.vmlinux.bin.o
if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
echo >&2 "Failed to generate BTF for vmlinux"
echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
exit 1
fi
fi
kallsymso=""
kallsymso_prev=""
kallsyms_vmlinux=""
if [ -n "${CONFIG_KALLSYMS}" ]; then
# kallsyms support
# Generate section listing all symbols and add it into vmlinux
# It's a three step process:
# 1) Link .tmp_vmlinux1 so it has all symbols and sections,
# but __kallsyms is empty.
# Running kallsyms on that gives us .tmp_kallsyms1.o with
# the right size
# 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of
# the right size, but due to the added section, some
# addresses have shifted.
# From here, we generate a correct .tmp_kallsyms2.o
# 3) That link may have expanded the kernel image enough that
# more linker branch stubs / trampolines had to be added, which
# introduces new names, which further expands kallsyms. Do another
# pass if that is the case. In theory it's possible this results
# in even more stubs, but unlikely.
# KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
# other bugs.
# 4) The correct ${kallsymso} is linked into the final vmlinux.
#
# a) Verify that the System.map from vmlinux matches the map from
# ${kallsymso}.
kallsyms_step 1
kallsyms_step 2
# step 3
size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
kallsyms_step 3
fi
fi
vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
# fill in BTF IDs
if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then
info BTFIDS vmlinux
${RESOLVE_BTFIDS} vmlinux
fi
if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
info SORTTAB vmlinux
if ! sorttable vmlinux; then
echo >&2 Failed to sort kernel tables
exit 1
fi
fi
info SYSMAP System.map
mksysmap vmlinux System.map
# step a (see comment above)
if [ -n "${CONFIG_KALLSYMS}" ]; then
mksysmap ${kallsyms_vmlinux} .tmp_System.map
if ! cmp -s System.map .tmp_System.map; then
echo >&2 Inconsistent kallsyms data
echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
exit 1
fi
fi
# For fixdep
echo "vmlinux: $0" > .vmlinux.d