summaryrefslogtreecommitdiff
path: root/scripts
diff options
context:
space:
mode:
authorMasahiro Yamada <masahiroy@kernel.org>2022-05-13 14:39:22 +0300
committerMasahiro Yamada <masahiroy@kernel.org>2022-05-24 10:33:20 +0300
commit7b4537199a4a8480b8c3ba37a2d44765ce76cd9b (patch)
tree0690afa62208ca15fd36069afcbdac85908d0676 /scripts
parentf292d875d0dc700b3af0bef04c5abc1dc7b3b62c (diff)
downloadlinux-7b4537199a4a8480b8c3ba37a2d44765ce76cd9b.tar.xz
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 <masahiroy@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nicolas Schier <nicolas@fjasle.eu> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
Diffstat (limited to 'scripts')
-rw-r--r--scripts/Makefile.build27
-rw-r--r--scripts/Makefile.vmlinux32
-rw-r--r--scripts/genksyms/genksyms.c18
-rwxr-xr-xscripts/link-vmlinux.sh10
-rw-r--r--scripts/mod/modpost.c28
5 files changed, 73 insertions, 42 deletions
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index a1023868775f..ddd9080fc028 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -128,7 +128,6 @@ $(obj)/%.i: $(src)/%.c FORCE
genksyms = scripts/genksyms/genksyms \
$(if $(1), -T $(2)) \
- $(if $(CONFIG_MODULE_REL_CRCS), -R) \
$(if $(KBUILD_PRESERVE), -p) \
-r $(or $(wildcard $(2:.symtypes=.symref)), /dev/null)
@@ -162,19 +161,11 @@ ifdef CONFIG_MODVERSIONS
# o if <file>.o doesn't contain a __ksymtab version, i.e. does
# not export symbols, it's done.
# o otherwise, we calculate symbol versions using the good old
-# genksyms on the preprocessed source and postprocess them in a way
-# that they are usable as a linker script
-# o generate .tmp_<file>.o from <file>.o using the linker to
-# replace the unresolved symbols __crc_exported_symbol with
-# the actual value of the checksum generated by genksyms
-# o remove .tmp_<file>.o to <file>.o
+# genksyms on the preprocessed source and dump them into the .cmd file.
+# o modpost will extract versions from that file and create *.c files that will
+# be compiled and linked to the kernel and/or modules.
-# Generate .o.symversions files for each .o with exported symbols, and link these
-# to the kernel and/or modules at the end.
-
-genksyms_format_rel_crc := [^_]*__crc_\([^ ]*\) = \.; LONG(\([^)]*\)).*
-genksyms_format_normal := __crc_\(.*\) = \(.*\);
-genksyms_format := $(if $(CONFIG_MODULE_REL_CRCS),$(genksyms_format_rel_crc),$(genksyms_format_normal))
+genksyms_format := __crc_\(.*\) = \(.*\);
gen_symversions = \
if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then \
@@ -188,12 +179,6 @@ gen_symversions = \
cmd_gen_symversions_c = $(call gen_symversions,c)
-cmd_modversions = \
- if [ -r $@.symversions ]; then \
- $(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ \
- -T $@.symversions; \
- mv -f $(@D)/.tmp_$(@F) $@; \
- fi
endif
ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
@@ -273,7 +258,6 @@ define rule_cc_o_c
$(call cmd,checkdoc)
$(call cmd,gen_objtooldep)
$(call cmd,gen_symversions_c)
- $(if $(CONFIG_LTO_CLANG),,$(call cmd,modversions))
$(call cmd,record_mcount)
endef
@@ -282,7 +266,6 @@ define rule_as_o_S
$(call cmd,gen_ksymdeps)
$(call cmd,gen_objtooldep)
$(call cmd,gen_symversions_S)
- $(call cmd,modversions)
endef
# Built-in and composite module parts
@@ -296,8 +279,6 @@ ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),)
quiet_cmd_cc_prelink_modules = LD [M] $@
cmd_cc_prelink_modules = \
$(LD) $(ld_flags) -r -o $@ \
- $(shell [ -s $(@:.prelink.o=.o.symversions) ] && \
- echo -T $(@:.prelink.o=.o.symversions)) \
--whole-archive $(filter-out FORCE,$^) \
$(cmd_objtool)
diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
new file mode 100644
index 000000000000..7a63abf22399
--- /dev/null
+++ b/scripts/Makefile.vmlinux
@@ -0,0 +1,32 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+include include/config/auto.conf
+include $(srctree)/scripts/Kbuild.include
+
+# for c_flags
+include $(srctree)/scripts/Makefile.lib
+
+quiet_cmd_cc_o_c = CC $@
+ cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
+
+%.o: %.c FORCE
+ $(call if_changed_dep,cc_o_c)
+
+targets := $(MAKECMDGOALS)
+
+# Add FORCE to the prequisites of a target to force it to be always rebuilt.
+# ---------------------------------------------------------------------------
+
+PHONY += FORCE
+FORCE:
+
+# Read all saved command lines and dependencies for the $(targets) we
+# may be building above, using $(if_changed{,_dep}). As an
+# optimization, we don't need to read them if the target does not
+# exist, we will rebuild anyway in that case.
+
+existing-targets := $(wildcard $(sort $(targets)))
+
+-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
+
+.PHONY: $(PHONY)
diff --git a/scripts/genksyms/genksyms.c b/scripts/genksyms/genksyms.c
index 4827c5abe5b7..67b23cc0df0f 100644
--- a/scripts/genksyms/genksyms.c
+++ b/scripts/genksyms/genksyms.c
@@ -33,7 +33,7 @@ char *cur_filename;
int in_source_file;
static int flag_debug, flag_dump_defs, flag_reference, flag_dump_types,
- flag_preserve, flag_warnings, flag_rel_crcs;
+ flag_preserve, flag_warnings;
static int errors;
static int nsyms;
@@ -680,11 +680,7 @@ void export_symbol(const char *name)
if (flag_dump_defs)
fputs(">\n", debugfile);
- /* Used as a linker script. */
- printf(!flag_rel_crcs ? "__crc_%s = 0x%08lx;\n" :
- "SECTIONS { .rodata : ALIGN(4) { "
- "__crc_%s = .; LONG(0x%08lx); } }\n",
- name, crc);
+ printf("__crc_%s = 0x%08lx;\n", name, crc);
}
}
@@ -733,7 +729,6 @@ static void genksyms_usage(void)
" -q, --quiet Disable warnings (default)\n"
" -h, --help Print this message\n"
" -V, --version Print the release version\n"
- " -R, --relative-crc Emit section relative symbol CRCs\n"
#else /* __GNU_LIBRARY__ */
" -s Select symbol prefix\n"
" -d Increment the debug level (repeatable)\n"
@@ -745,7 +740,6 @@ static void genksyms_usage(void)
" -q Disable warnings (default)\n"
" -h Print this message\n"
" -V Print the release version\n"
- " -R Emit section relative symbol CRCs\n"
#endif /* __GNU_LIBRARY__ */
, stderr);
}
@@ -766,14 +760,13 @@ int main(int argc, char **argv)
{"preserve", 0, 0, 'p'},
{"version", 0, 0, 'V'},
{"help", 0, 0, 'h'},
- {"relative-crc", 0, 0, 'R'},
{0, 0, 0, 0}
};
- while ((o = getopt_long(argc, argv, "s:dwqVDr:T:phR",
+ while ((o = getopt_long(argc, argv, "s:dwqVDr:T:ph",
&long_opts[0], NULL)) != EOF)
#else /* __GNU_LIBRARY__ */
- while ((o = getopt(argc, argv, "s:dwqVDr:T:phR")) != EOF)
+ while ((o = getopt(argc, argv, "s:dwqVDr:T:ph")) != EOF)
#endif /* __GNU_LIBRARY__ */
switch (o) {
case 'd':
@@ -813,9 +806,6 @@ int main(int argc, char **argv)
case 'h':
genksyms_usage();
return 0;
- case 'R':
- flag_rel_crcs = 1;
- break;
default:
genksyms_usage();
return 1;
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index eceb3ee7ec06..db34dc3163ae 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -90,7 +90,6 @@ modpost_link()
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 @@ vmlinux_link()
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 @@ cleanup()
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 @@ info GEN modules.builtin
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
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 1e2949775e1b..42e949cbc255 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2234,6 +2234,7 @@ static void add_header(struct buffer *b, struct module *mod)
buf_printf(b, "#define INCLUDE_VERMAGIC\n");
buf_printf(b, "#include <linux/build-salt.h>\n");
buf_printf(b, "#include <linux/elfnote-lto.h>\n");
+ buf_printf(b, "#include <linux/export-internal.h>\n");
buf_printf(b, "#include <linux/vermagic.h>\n");
buf_printf(b, "#include <linux/compiler.h>\n");
buf_printf(b, "\n");
@@ -2268,20 +2269,26 @@ static void add_header(struct buffer *b, struct module *mod)
buf_printf(b, "\nMODULE_INFO(staging, \"Y\");\n");
}
-static void check_symversions(struct module *mod)
+static void add_exported_symbols(struct buffer *buf, struct module *mod)
{
struct symbol *sym;
if (!modversions)
return;
+ /* record CRCs for exported symbols */
+ buf_printf(buf, "\n");
list_for_each_entry(sym, &mod->exported_symbols, list) {
if (!sym->crc_valid) {
warn("EXPORT symbol \"%s\" [%s%s] version generation failed, symbol will not be versioned.\n"
"Is \"%s\" prototyped in <asm/asm-prototypes.h>?\n",
sym->name, mod->name, mod->is_vmlinux ? "" : ".ko",
sym->name);
+ continue;
}
+
+ buf_printf(buf, "SYMBOL_CRC(%s, 0x%08x, \"%s\");\n",
+ sym->name, sym->crc, sym->is_gpl_only ? "_gpl" : "");
}
}
@@ -2418,6 +2425,18 @@ static void write_if_changed(struct buffer *b, const char *fname)
write_buf(b, fname);
}
+static void write_vmlinux_export_c_file(struct module *mod)
+{
+ struct buffer buf = { };
+
+ buf_printf(&buf,
+ "#include <linux/export-internal.h>\n");
+
+ add_exported_symbols(&buf, mod);
+ write_if_changed(&buf, ".vmlinux.export.c");
+ free(buf.p);
+}
+
/* do sanity checks, and generate *.mod.c file */
static void write_mod_c_file(struct module *mod)
{
@@ -2429,6 +2448,7 @@ static void write_mod_c_file(struct module *mod)
check_exports(mod);
add_header(&buf, mod);
+ add_exported_symbols(&buf, mod);
add_versions(&buf, mod);
add_depends(&buf, mod);
add_moddevtable(&buf, mod);
@@ -2626,9 +2646,9 @@ int main(int argc, char **argv)
if (mod->from_dump)
continue;
- check_symversions(mod);
-
- if (!mod->is_vmlinux)
+ if (mod->is_vmlinux)
+ write_vmlinux_export_c_file(mod);
+ else
write_mod_c_file(mod);
}