#!/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()
  {
  	if [ "${quiet}" != "silent_" ]; then

  		printf "  %-7s %s
  " "${1}" "${2}"

  	fi
  }

  # 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"
  	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
  		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 lds="${objtree}/${KBUILD_LDS}"

  	local output=${1}

  	local objects

  	local strip_debug

  	info LD ${output}

  	# skip output file argument
  	shift

  	# The kallsyms linking does not need debug symbols included.
  	if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
  		strip_debug=-Wl,--strip-debug
  	fi

  	if [ "${SRCARCH}" != "um" ]; then

  		if [ -n "${CONFIG_LTO_CLANG}" ]; then
  			# Use vmlinux.o instead of performing the slow LTO
  			# link again.
  			objects="--whole-archive		\
  				vmlinux.o 			\
  				--no-whole-archive		\
  				${@}"
  		else
  			objects="--whole-archive		\
  				${KBUILD_VMLINUX_OBJS}		\
  				--no-whole-archive		\
  				--start-group			\
  				${KBUILD_VMLINUX_LIBS}		\
  				--end-group			\
  				${@}"
  		fi

  		${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}	\

  			${strip_debug#-Wl,}			\

  			-o ${output}				\

  			-T ${lds} ${objects}

  	else

  		objects="-Wl,--whole-archive			\

  			${KBUILD_VMLINUX_OBJS}			\

  			-Wl,--no-whole-archive			\
  			-Wl,--start-group			\
  			${KBUILD_VMLINUX_LIBS}			\
  			-Wl,--end-group				\

  			${@}"

  		${CC} ${CFLAGS_vmlinux}				\

  			${strip_debug}				\

  			-o ${output}				\

  			-Wl,-T,${lds}				\
  			${objects}				\

  			-lutil -lrt -lpthread

  		rm -f linux
  	fi
  }

  # 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 ${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} ${2} 2>/dev/null
  	# Change e_type to ET_REL so that it can be used to link final vmlinux.
  	# Unlike GNU ld, lld does not allow an ET_EXEC input.
  	printf '\1' | dd of=${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 ${kallsyms_S}
  	${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.o
  }

  on_exit()
  {
  	if [ $? -ne 0 ]; then
  		cleanup
  	fi
  }
  trap on_exit EXIT
  
  on_signals()
  {
  	exit 1
  }
  trap on_signals HUP INT QUIT TERM

  # 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' '
  ' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
  	tr ' ' '
  ' | 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