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![Chris Down](/assets/img/avatar_default.png)
When trying to compile with CONFIG_DEBUG_INFO_BTF enabled, I got this error: % make -s Failed to generate BTF for vmlinux Try to disable CONFIG_DEBUG_INFO_BTF make[3]: *** [vmlinux] Error 1 Compiling again without -s shows the true error (that pahole is missing), but since this is fatal, we should show the error unconditionally on stderr as well, not silence it using the `info` function. With this patch: % make -s BTF: .tmp_vmlinux.btf: pahole (pahole) is not available Failed to generate BTF for vmlinux Try to disable CONFIG_DEBUG_INFO_BTF make[3]: *** [vmlinux] Error 1 Signed-off-by: Chris Down <chris@chrisdown.name> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200122000110.GA310073@chrisdown.name
324 lines
7.7 KiB
Bash
Executable file
324 lines
7.7 KiB
Bash
Executable file
#!/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_OBJS) and
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# $(KBUILD_VMLINUX_LIBS). Most are built-in.a files from top-level directories
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# in the kernel tree, others are specified in arch/$(ARCH)/Makefile.
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# $(KBUILD_VMLINUX_LIBS) are archives which are linked conditionally
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# (not within --whole-archive), and do not 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_OBJS)
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# | +--< init/built-in.a 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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# Link of vmlinux.o used for section mismatch analysis
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# ${1} output file
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modpost_link()
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{
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local objects
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objects="--whole-archive \
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${KBUILD_VMLINUX_OBJS} \
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--no-whole-archive \
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--start-group \
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${KBUILD_VMLINUX_LIBS} \
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--end-group"
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${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${objects}
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}
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# Link of vmlinux
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# ${1} - output file
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# ${2}, ${3}, ... - optional extra .o files
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vmlinux_link()
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{
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local lds="${objtree}/${KBUILD_LDS}"
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local output=${1}
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local objects
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info LD ${output}
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# skip output file argument
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shift
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if [ "${SRCARCH}" != "um" ]; then
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objects="--whole-archive \
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${KBUILD_VMLINUX_OBJS} \
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--no-whole-archive \
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--start-group \
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${KBUILD_VMLINUX_LIBS} \
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--end-group \
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${@}"
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${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \
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-o ${output} \
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-T ${lds} ${objects}
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else
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objects="-Wl,--whole-archive \
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${KBUILD_VMLINUX_OBJS} \
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-Wl,--no-whole-archive \
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-Wl,--start-group \
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${KBUILD_VMLINUX_LIBS} \
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-Wl,--end-group \
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${@}"
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${CC} ${CFLAGS_vmlinux} \
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-o ${output} \
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-Wl,-T,${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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# generate .BTF typeinfo from DWARF debuginfo
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# ${1} - vmlinux image
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# ${2} - file to dump raw BTF data into
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gen_btf()
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{
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local pahole_ver
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local bin_arch
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if ! [ -x "$(command -v ${PAHOLE})" ]; then
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echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
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return 1
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fi
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pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
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if [ "${pahole_ver}" -lt "113" ]; then
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echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13"
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return 1
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fi
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info "BTF" ${2}
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vmlinux_link ${1}
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LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
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# dump .BTF section into raw binary file to link with final vmlinux
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bin_arch=$(LANG=C ${OBJDUMP} -f ${1} | grep architecture | \
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cut -d, -f1 | cut -d' ' -f2)
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bin_format=$(LANG=C ${OBJDUMP} -f ${1} | grep 'file format' | \
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awk '{print $4}')
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${OBJCOPY} --change-section-address .BTF=0 \
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--set-section-flags .BTF=alloc -O binary \
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--only-section=.BTF ${1} .btf.vmlinux.bin
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${OBJCOPY} -I binary -O ${bin_format} -B ${bin_arch} \
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--rename-section .data=.BTF .btf.vmlinux.bin ${2}
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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} ${afile}
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}
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# Perform one step in kallsyms generation, including temporary linking of
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# vmlinux.
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kallsyms_step()
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{
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kallsymso_prev=${kallsymso}
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kallsymso=.tmp_kallsyms${1}.o
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kallsyms_vmlinux=.tmp_vmlinux${1}
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vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
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kallsyms ${kallsyms_vmlinux} ${kallsymso}
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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 .btf.*
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rm -f .tmp_System.map
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rm -f .tmp_kallsyms*
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rm -f .tmp_vmlinux*
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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 "${srctree}/scripts/Makefile.build" obj=init
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#link vmlinux.o
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info LD vmlinux.o
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modpost_link vmlinux.o
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# modpost vmlinux.o to check for section mismatches
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${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
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info MODINFO modules.builtin.modinfo
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${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
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btf_vmlinux_bin_o=""
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if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
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if gen_btf .tmp_vmlinux.btf .btf.vmlinux.bin.o ; then
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btf_vmlinux_bin_o=.btf.vmlinux.bin.o
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else
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echo >&2 "Failed to generate BTF for vmlinux"
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echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
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exit 1
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fi
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fi
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kallsymso=""
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kallsymso_prev=""
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kallsyms_vmlinux=""
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if [ -n "${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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# ${kallsymso}.
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kallsyms_step 1
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kallsyms_step 2
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# step 3
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size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
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size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
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if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
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kallsyms_step 3
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fi
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fi
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vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
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if [ -n "${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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