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b1a1a1a09b
With LTO, LLVM bitcode won't be compiled into native code until modpost_link, or modfinal for modules. This change postpones calls to objtool until after these steps, and moves objtool_args to Makefile.lib, so the arguments can be reused in Makefile.modfinal. As we didn't have objects to process earlier, we use --duplicate when processing vmlinux.o. This change also disables unreachable instruction warnings with LTO to avoid warnings about the int3 padding between functions. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Kees Cook <keescook@chromium.org>
443 lines
11 KiB
Bash
Executable file
443 lines
11 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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LD="$1"
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KBUILD_LDFLAGS="$2"
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LDFLAGS_vmlinux="$3"
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# Nice output in kbuild format
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# Will be supressed by "make -s"
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info()
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{
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if [ "${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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# Generate a linker script to ensure correct ordering of initcalls.
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gen_initcalls()
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{
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info GEN .tmp_initcalls.lds
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${PYTHON} ${srctree}/scripts/jobserver-exec \
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${PERL} ${srctree}/scripts/generate_initcall_order.pl \
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${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS} \
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> .tmp_initcalls.lds
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}
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# If CONFIG_LTO_CLANG is selected, collect generated symbol versions into
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# .tmp_symversions.lds
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gen_symversions()
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{
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info GEN .tmp_symversions.lds
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rm -f .tmp_symversions.lds
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for o in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do
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if [ -f ${o}.symversions ]; then
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cat ${o}.symversions >> .tmp_symversions.lds
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fi
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done
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}
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# Link of vmlinux.o used for section mismatch analysis
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# ${1} output file
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modpost_link()
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{
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local objects
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local lds=""
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objects="--whole-archive \
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${KBUILD_VMLINUX_OBJS} \
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--no-whole-archive \
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--start-group \
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${KBUILD_VMLINUX_LIBS} \
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--end-group"
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if [ -n "${CONFIG_LTO_CLANG}" ]; then
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gen_initcalls
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lds="-T .tmp_initcalls.lds"
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if [ -n "${CONFIG_MODVERSIONS}" ]; then
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gen_symversions
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lds="${lds} -T .tmp_symversions.lds"
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fi
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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 ${1}
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else
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info LD ${1}
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fi
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${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects}
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}
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objtool_link()
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{
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local objtoolcmd;
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local objtoolopt;
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if [ "${CONFIG_LTO_CLANG} ${CONFIG_STACK_VALIDATION}" = "y y" ]; then
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# Don't perform vmlinux validation unless explicitly requested,
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# but run objtool on vmlinux.o now that we have an object file.
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if [ -n "${CONFIG_UNWINDER_ORC}" ]; then
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objtoolcmd="orc generate"
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fi
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objtoolopt="${objtoolopt} --duplicate"
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if [ -n "${CONFIG_FTRACE_MCOUNT_USE_OBJTOOL}" ]; then
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objtoolopt="${objtoolopt} --mcount"
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fi
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fi
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if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then
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objtoolopt="${objtoolopt} --noinstr"
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fi
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if [ -n "${objtoolopt}" ]; then
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if [ -z "${objtoolcmd}" ]; then
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objtoolcmd="check"
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fi
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objtoolopt="${objtoolopt} --vmlinux"
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if [ -z "${CONFIG_FRAME_POINTER}" ]; then
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objtoolopt="${objtoolopt} --no-fp"
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fi
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if [ -n "${CONFIG_GCOV_KERNEL}" ] || [ -n "${CONFIG_LTO_CLANG}" ]; then
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objtoolopt="${objtoolopt} --no-unreachable"
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fi
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if [ -n "${CONFIG_RETPOLINE}" ]; then
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objtoolopt="${objtoolopt} --retpoline"
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fi
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if [ -n "${CONFIG_X86_SMAP}" ]; then
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objtoolopt="${objtoolopt} --uaccess"
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fi
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info OBJTOOL ${1}
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tools/objtool/objtool ${objtoolcmd} ${objtoolopt} ${1}
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fi
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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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local strip_debug
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info LD ${output}
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# skip output file argument
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shift
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# The kallsyms linking does not need debug symbols included.
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if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
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strip_debug=-Wl,--strip-debug
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fi
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if [ "${SRCARCH}" != "um" ]; then
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if [ -n "${CONFIG_LTO_CLANG}" ]; then
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# Use vmlinux.o instead of performing the slow LTO
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# link again.
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objects="--whole-archive \
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vmlinux.o \
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--no-whole-archive \
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${@}"
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else
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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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${@}"
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fi
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${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \
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${strip_debug#-Wl,} \
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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} ${CFLAGS_vmlinux} \
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${strip_debug} \
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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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# ${2} - file to dump raw BTF data into
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gen_btf()
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{
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local pahole_ver
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if ! [ -x "$(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 "116" ]; then
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echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
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return 1
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fi
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vmlinux_link ${1}
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info "BTF" ${2}
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LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
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# Create ${2} which contains just .BTF section but no symbols. Add
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# SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
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# deletes all symbols including __start_BTF and __stop_BTF, which will
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# be redefined in the linker script. Add 2>/dev/null to suppress GNU
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# objcopy warnings: "empty loadable segment detected at ..."
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${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
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--strip-all ${1} ${2} 2>/dev/null
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# Change e_type to ET_REL so that it can be used to link final vmlinux.
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# Unlike GNU ld, lld does not allow an ET_EXEC input.
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printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
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}
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# Create ${2} .S file with all symbols from the ${1} object file
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kallsyms()
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{
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local kallsymopt;
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if [ -n "${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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info KSYMS ${2}
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${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2}
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}
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# Perform one step in kallsyms generation, including temporary linking of
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# vmlinux.
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kallsyms_step()
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{
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kallsymso_prev=${kallsymso}
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kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
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kallsymso=${kallsyms_vmlinux}.o
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kallsyms_S=${kallsyms_vmlinux}.S
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vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
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kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
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info AS ${kallsyms_S}
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${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
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${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
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-c -o ${kallsymso} ${kallsyms_S}
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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} ${2}
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}
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sorttable()
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{
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${objtree}/scripts/sorttable ${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_initcalls.lds
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rm -f .tmp_symversions.lds
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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 [ $? -ne 0 ]; then
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cleanup
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fi
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}
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trap on_exit EXIT
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on_signals()
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{
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exit 1
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}
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trap on_signals HUP INT QUIT TERM
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# Use "make V=1" to debug this script
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case "${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 "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
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#link vmlinux.o
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modpost_link vmlinux.o
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objtool_link vmlinux.o
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# modpost vmlinux.o to check for section mismatches
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${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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info GEN modules.builtin
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# The second line aids cases where multiple modules share the same object.
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tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
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tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
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btf_vmlinux_bin_o=""
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if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
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btf_vmlinux_bin_o=.btf.vmlinux.bin.o
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if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
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echo >&2 "Failed to generate BTF for vmlinux"
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echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
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exit 1
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fi
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fi
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kallsymso=""
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kallsymso_prev=""
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kallsyms_vmlinux=""
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if [ -n "${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}" ${btf_vmlinux_bin_o}
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# fill in BTF IDs
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if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then
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info BTFIDS vmlinux
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${RESOLVE_BTFIDS} vmlinux
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fi
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if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
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info SORTTAB vmlinux
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if ! sorttable vmlinux; then
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echo >&2 Failed to sort kernel tables
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exit 1
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fi
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fi
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info SYSMAP System.map
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mksysmap vmlinux System.map
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# step a (see comment above)
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if [ -n "${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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