#!/bin/sh
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# SPDX-License-Identifier: GPL-2.0
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#
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# link vmlinux
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#
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# vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_INIT) and
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# $(KBUILD_VMLINUX_MAIN) and $(KBUILD_VMLINUX_LIBS). Most are built-in.a files
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# from top-level directories in the kernel tree, others are specified in
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# arch/$(ARCH)/Makefile. Ordering when linking is important, and
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# $(KBUILD_VMLINUX_INIT) must be first. $(KBUILD_VMLINUX_LIBS) are archives
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# which are linked conditionally (not within --whole-archive), and do not
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# require symbol indexes added.
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#
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# vmlinux
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# ^
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# |
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# +-< $(KBUILD_VMLINUX_INIT)
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# | +--< init/version.o + more
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# |
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# +--< $(KBUILD_VMLINUX_MAIN)
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# | +--< drivers/built-in.a mm/built-in.a + more
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# |
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# +--< $(KBUILD_VMLINUX_LIBS)
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# | +--< lib/lib.a + more
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# |
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# +-< ${kallsymso} (see description in KALLSYMS section)
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#
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# vmlinux version (uname -v) cannot be updated during normal
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# descending-into-subdirs phase since we do not yet know if we need to
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# update vmlinux.
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# Therefore this step is delayed until just before final link of vmlinux.
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#
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# System.map is generated to document addresses of all kernel symbols
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# Error out on error
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set -e
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# Nice output in kbuild format
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# Will be supressed by "make -s"
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info()
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{
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if [ "${quiet}" != "silent_" ]; then
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printf " %-7s %s\n" ${1} ${2}
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fi
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}
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# Thin archive build here makes a final archive with symbol table and indexes
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# from vmlinux objects INIT and MAIN, which can be used as input to linker.
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# KBUILD_VMLINUX_LIBS archives should already have symbol table and indexes
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# added.
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#
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# Traditional incremental style of link does not require this step
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#
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# built-in.a output file
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#
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archive_builtin()
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{
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info AR built-in.a
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rm -f built-in.a;
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${AR} rcsTP${KBUILD_ARFLAGS} built-in.a \
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${KBUILD_VMLINUX_INIT} \
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${KBUILD_VMLINUX_MAIN}
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# rebuild with llvm-ar to update the symbol table
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if [ -n "${CONFIG_LTO_CLANG}" ]; then
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mv -f built-in.a built-in.a.tmp
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${LLVM_AR} rcsT${KBUILD_ARFLAGS} built-in.a $(${AR} t built-in.a.tmp)
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rm -f built-in.a.tmp
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fi
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}
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# If CONFIG_LTO_CLANG is selected, generate a linker script to ensure correct
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# ordering of initcalls, and with CONFIG_MODVERSIONS also enabled, collect the
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# previously generated symbol versions into the same script.
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lto_lds()
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{
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if [ -z "${CONFIG_LTO_CLANG}" ]; then
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return
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fi
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${srctree}/scripts/generate_initcall_order.pl \
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built-in.a ${KBUILD_VMLINUX_LIBS} \
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> .tmp_lto.lds
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if [ -n "${CONFIG_MODVERSIONS}" ]; then
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for a in built-in.a ${KBUILD_VMLINUX_LIBS}; do
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for o in $(${AR} t $a); do
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if [ -f ${o}.symversions ]; then
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cat ${o}.symversions >> .tmp_lto.lds
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fi
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done
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done
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fi
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echo "-T .tmp_lto.lds"
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}
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# Link of vmlinux.o used for section mismatch analysis
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# ${1} output file
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modpost_link()
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{
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local objects
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objects="--whole-archive \
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built-in.a \
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--no-whole-archive \
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--start-group \
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${KBUILD_VMLINUX_LIBS} \
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--end-group"
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if [ -n "${CONFIG_LTO_CLANG}" ]; then
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# This might take a while, so indicate that we're doing
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# an LTO link
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info LTO vmlinux.o
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fi
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${LD} ${KBUILD_LDFLAGS} -r -o ${1} $(lto_lds) ${objects}
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}
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# If CONFIG_LTO_CLANG is selected, we postpone running recordmcount until
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# we have compiled LLVM IR to an object file.
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recordmcount()
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{
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if [ -z "${CONFIG_LTO_CLANG}" ]; then
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return
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fi
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if [ -n "${CONFIG_FTRACE_MCOUNT_RECORD}" ]; then
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scripts/recordmcount ${RECORDMCOUNT_FLAGS} $*
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fi
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}
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# Link of vmlinux
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# ${1} - optional extra .o files
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# ${2} - output file
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vmlinux_link()
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{
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local lds="${objtree}/${KBUILD_LDS}"
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local objects
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if [ "${SRCARCH}" != "um" ]; then
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if [ -z "${CONFIG_LTO_CLANG}" ]; then
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objects="--whole-archive \
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built-in.a \
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--no-whole-archive \
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--start-group \
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${KBUILD_VMLINUX_LIBS} \
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--end-group \
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${1}"
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else
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objects="--start-group \
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vmlinux.o \
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--end-group \
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${1}"
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fi
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${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} -o ${2} \
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-T ${lds} ${objects}
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else
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objects="-Wl,--whole-archive \
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built-in.a \
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-Wl,--no-whole-archive \
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-Wl,--start-group \
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${KBUILD_VMLINUX_LIBS} \
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-Wl,--end-group \
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${1}"
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${CC} ${CFLAGS_vmlinux} -o ${2} \
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-Wl,-T,${lds} \
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${objects} \
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-lutil -lrt -lpthread
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rm -f linux
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fi
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}
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# Create ${2} .o file with all symbols from the ${1} object file
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kallsyms()
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{
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info KSYM ${2}
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local kallsymopt;
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if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
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kallsymopt="${kallsymopt} --all-symbols"
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fi
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if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
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kallsymopt="${kallsymopt} --absolute-percpu"
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fi
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if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
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kallsymopt="${kallsymopt} --base-relative"
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fi
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local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
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${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
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local afile="`basename ${2} .o`.S"
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${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile}
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${CC} ${aflags} -c -o ${2} ${afile}
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}
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# Create map file with all symbols from ${1}
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# See mksymap for additional details
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mksysmap()
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{
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${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
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}
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sortextable()
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{
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${objtree}/scripts/sortextable ${1}
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}
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# Delete output files in case of error
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cleanup()
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{
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rm -f .tmp_System.map
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rm -f .tmp_kallsyms*
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rm -f .tmp_lto.lds
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rm -f .tmp_vmlinux*
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rm -f built-in.a
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rm -f System.map
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rm -f vmlinux
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rm -f vmlinux.o
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}
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on_exit()
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{
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if [ $? -ne 0 ]; then
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cleanup
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fi
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}
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trap on_exit EXIT
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on_signals()
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{
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exit 1
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}
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trap on_signals HUP INT QUIT TERM
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#
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#
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# Use "make V=1" to debug this script
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case "${KBUILD_VERBOSE}" in
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*1*)
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set -x
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;;
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esac
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if [ "$1" = "clean" ]; then
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cleanup
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exit 0
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fi
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# We need access to CONFIG_ symbols
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. include/config/auto.conf
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# Update version
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info GEN .version
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if [ -r .version ]; then
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VERSION=$(expr 0$(cat .version) + 1)
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echo $VERSION > .version
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else
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rm -f .version
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echo 1 > .version
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fi;
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# final build of init/
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${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
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archive_builtin
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#link vmlinux.o
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modpost_link vmlinux.o
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# modpost vmlinux.o to check for section mismatches
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${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o
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if [ -n "${CONFIG_LTO_CLANG}" ]; then
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# Call recordmcount if needed
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recordmcount vmlinux.o
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fi
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kallsymso=""
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kallsyms_vmlinux=""
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if [ -n "${CONFIG_KALLSYMS}" ]; then
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# kallsyms support
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# Generate section listing all symbols and add it into vmlinux
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# It's a three step process:
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# 1) Link .tmp_vmlinux1 so it has all symbols and sections,
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# but __kallsyms is empty.
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# Running kallsyms on that gives us .tmp_kallsyms1.o with
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# the right size
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# 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of
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# the right size, but due to the added section, some
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# addresses have shifted.
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# From here, we generate a correct .tmp_kallsyms2.o
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# 3) That link may have expanded the kernel image enough that
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# more linker branch stubs / trampolines had to be added, which
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# introduces new names, which further expands kallsyms. Do another
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# pass if that is the case. In theory it's possible this results
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# in even more stubs, but unlikely.
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# KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
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# other bugs.
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# 4) The correct ${kallsymso} is linked into the final vmlinux.
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#
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# a) Verify that the System.map from vmlinux matches the map from
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# ${kallsymso}.
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kallsymso=.tmp_kallsyms2.o
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kallsyms_vmlinux=.tmp_vmlinux2
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# step 1
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vmlinux_link "" .tmp_vmlinux1
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kallsyms .tmp_vmlinux1 .tmp_kallsyms1.o
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# step 2
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vmlinux_link .tmp_kallsyms1.o .tmp_vmlinux2
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kallsyms .tmp_vmlinux2 .tmp_kallsyms2.o
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# step 3
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size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" .tmp_kallsyms1.o)
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size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" .tmp_kallsyms2.o)
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if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
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kallsymso=.tmp_kallsyms3.o
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kallsyms_vmlinux=.tmp_vmlinux3
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vmlinux_link .tmp_kallsyms2.o .tmp_vmlinux3
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kallsyms .tmp_vmlinux3 .tmp_kallsyms3.o
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fi
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fi
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info LD vmlinux
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vmlinux_link "${kallsymso}" vmlinux
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if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
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info SORTEX vmlinux
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sortextable vmlinux
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fi
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info SYSMAP System.map
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mksysmap vmlinux System.map
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# step a (see comment above)
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if [ -n "${CONFIG_KALLSYMS}" ]; then
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mksysmap ${kallsyms_vmlinux} .tmp_System.map
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if ! cmp -s System.map .tmp_System.map; then
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echo >&2 Inconsistent kallsyms data
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echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
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exit 1
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fi
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fi
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