kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS
include/{linux,asm-generic}/export.h defines a weak symbol, __crc_*
as a placeholder.
Genksyms writes the version CRCs into the linker script, which will be
used for filling the __crc_* symbols. The linker script format depends
on CONFIG_MODULE_REL_CRCS. If it is enabled, __crc_* holds the offset
to the reference of CRC.
It is time to get rid of this complexity.
Now that modpost parses text files (.*.cmd) to collect all the CRCs,
it can generate C code that will be linked to the vmlinux or modules.
Generate a new C file, .vmlinux.export.c, which contains the CRCs of
symbols exported by vmlinux. It is compiled and linked to vmlinux in
scripts/link-vmlinux.sh.
Put the CRCs of symbols exported by modules into the existing *.mod.c
files. No additional build step is needed for modules. As before,
*.mod.c are compiled and linked to *.ko in scripts/Makefile.modfinal.
No linker magic is used here. The new C implementation works in the
same way, whether CONFIG_RELOCATABLE is enabled or not.
CONFIG_MODULE_REL_CRCS is no longer needed.
Previously, Kbuild invoked additional $(LD) to update the CRCs in
objects, but this step is unneeded too.
Signed-off-by: Masahiro Yamada <[email protected]>
Tested-by: Nathan Chancellor <[email protected]>
Tested-by: Nicolas Schier <[email protected]>
Reviewed-by: Nicolas Schier <[email protected]>
Tested-by: Sedat Dilek <[email protected]> # LLVM-14 (x86-64)
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index eceb3ee..db34dc3 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -90,7 +90,6 @@
if is_enabled CONFIG_MODVERSIONS; then
gen_symversions
- lds="${lds} -T .tmp_symversions.lds"
fi
# This might take a while, so indicate that we're doing
@@ -183,6 +182,10 @@
libs="${KBUILD_VMLINUX_LIBS}"
fi
+ if is_enabled CONFIG_MODULES; then
+ objs="${objs} .vmlinux.export.o"
+ fi
+
if [ "${SRCARCH}" = "um" ]; then
wl=-Wl,
ld="${CC}"
@@ -312,6 +315,7 @@
rm -f vmlinux.o
rm -f .vmlinux.d
rm -f .vmlinux.objs
+ rm -f .vmlinux.export.c
}
# Use "make V=1" to debug this script
@@ -363,6 +367,10 @@
tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
+if is_enabled CONFIG_MODULES; then
+ ${MAKE} -f "${srctree}/scripts/Makefile.vmlinux" .vmlinux.export.o
+fi
+
btf_vmlinux_bin_o=""
if is_enabled CONFIG_DEBUG_INFO_BTF; then
btf_vmlinux_bin_o=.btf.vmlinux.bin.o
