On Mon, Sep 2, 2024 at 2:56 AM Thomas Weißschuh <linux@xxxxxxxxxxxxxx> wrote: > > Various information about modules is compiled into the info sections. > For that a dedicated .mod.c file is generated by modpost for each module > and then linked into the module. > However most of the information in the .mod.c is the same for all > modules, internal and external. > Split the shared information into a dedicated source file that is > compiled once and then linked into all modules. > > This avoids frequent rebuilds for all .mod.c files when using > CONFIG_LOCALVERSION_AUTO because the local version ends up in .mod.c > through UTS_RELEASE and VERMAGIC_STRING. > The modules are still relinked in this case. > > The code is also easier to maintain as it's now in a proper source file > instead of an inline string literal. > > Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx> Applied to linux-kbuild. Thanks! > --- > Changes in v2: > - Remove RFC status > - Incorporate Masahiro's proposals > - Rename modinfo.o to .module-common.o > - Build a dedicated .module-common.o for external modules > - Link to v1: https://lore.kernel.org/r/20240824-modinfo-const-v1-1-485f9c64b868@xxxxxxxxxxxxxx > --- > Masahiro, feel free to add some attribution for yourself when applying. > The new appraoch is pleasantly simpler. > --- > scripts/Makefile.modfinal | 7 +++++-- > scripts/mod/modpost.c | 23 ----------------------- > scripts/module-common.c | 25 +++++++++++++++++++++++++ > 3 files changed, 30 insertions(+), 25 deletions(-) > > diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal > index 306a6bb86e4d..6b1b72257b29 100644 > --- a/scripts/Makefile.modfinal > +++ b/scripts/Makefile.modfinal > @@ -30,6 +30,9 @@ quiet_cmd_cc_o_c = CC [M] $@ > %.mod.o: %.mod.c FORCE > $(call if_changed_dep,cc_o_c) > > +$(extmod_prefix).module-common.o: $(srctree)/scripts/module-common.c FORCE > + $(call if_changed_dep,cc_o_c) > + > quiet_cmd_ld_ko_o = LD [M] $@ > cmd_ld_ko_o += \ > $(LD) -r $(KBUILD_LDFLAGS) \ > @@ -54,13 +57,13 @@ if_changed_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check), \ > printf '%s\n' 'savedcmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:) > > # Re-generate module BTFs if either module's .ko or vmlinux changed > -%.ko: %.o %.mod.o scripts/module.lds $(and $(CONFIG_DEBUG_INFO_BTF_MODULES),$(KBUILD_BUILTIN),vmlinux) FORCE > +%.ko: %.o %.mod.o $(extmod_prefix).module-common.o scripts/module.lds $(and $(CONFIG_DEBUG_INFO_BTF_MODULES),$(KBUILD_BUILTIN),vmlinux) FORCE > +$(call if_changed_except,ld_ko_o,vmlinux) > ifdef CONFIG_DEBUG_INFO_BTF_MODULES > +$(if $(newer-prereqs),$(call cmd,btf_ko)) > endif > > -targets += $(modules:%.o=%.ko) $(modules:%.o=%.mod.o) > +targets += $(modules:%.o=%.ko) $(modules:%.o=%.mod.o) $(extmod_prefix).module-common.o > > # Add FORCE to the prerequisites of a target to force it to be always rebuilt. > # --------------------------------------------------------------------------- > diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c > index c8cd5d822bb6..107393a8c48a 100644 > --- a/scripts/mod/modpost.c > +++ b/scripts/mod/modpost.c > @@ -1755,26 +1755,9 @@ static void check_modname_len(struct module *mod) > static void add_header(struct buffer *b, struct module *mod) > { > buf_printf(b, "#include <linux/module.h>\n"); > - /* > - * Include build-salt.h after module.h in order to > - * inherit the definitions. > - */ > - 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"); > - buf_printf(b, "#ifdef CONFIG_UNWINDER_ORC\n"); > - buf_printf(b, "#include <asm/orc_header.h>\n"); > - buf_printf(b, "ORC_HEADER;\n"); > - buf_printf(b, "#endif\n"); > - buf_printf(b, "\n"); > - buf_printf(b, "BUILD_SALT;\n"); > - buf_printf(b, "BUILD_LTO_INFO;\n"); > - buf_printf(b, "\n"); > - buf_printf(b, "MODULE_INFO(vermagic, VERMAGIC_STRING);\n"); > buf_printf(b, "MODULE_INFO(name, KBUILD_MODNAME);\n"); > buf_printf(b, "\n"); > buf_printf(b, "__visible struct module __this_module\n"); > @@ -1792,12 +1775,6 @@ static void add_header(struct buffer *b, struct module *mod) > if (!external_module) > buf_printf(b, "\nMODULE_INFO(intree, \"Y\");\n"); > > - buf_printf(b, > - "\n" > - "#ifdef CONFIG_MITIGATION_RETPOLINE\n" > - "MODULE_INFO(retpoline, \"Y\");\n" > - "#endif\n"); > - > if (strstarts(mod->name, "drivers/staging")) > buf_printf(b, "\nMODULE_INFO(staging, \"Y\");\n"); > > diff --git a/scripts/module-common.c b/scripts/module-common.c > new file mode 100644 > index 000000000000..12fbc6d3aae8 > --- /dev/null > +++ b/scripts/module-common.c > @@ -0,0 +1,25 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +#include <linux/module.h> > +/* > + * Include build-salt.h after module.h in order to > + * inherit the definitions. > + */ > +#define INCLUDE_VERMAGIC > +#include <linux/build-salt.h> > +#include <linux/elfnote-lto.h> > +#include <linux/vermagic.h> > + > +#ifdef CONFIG_UNWINDER_ORC > +#include <asm/orc_header.h> > +ORC_HEADER; > +#endif > + > +BUILD_SALT; > +BUILD_LTO_INFO; > + > +MODULE_INFO(vermagic, VERMAGIC_STRING); > + > +#ifdef CONFIG_MITIGATION_RETPOLINE > +MODULE_INFO(retpoline, "Y"); > +#endif > > --- > base-commit: 9f18baf3dd656e7ca166038d51e0b54a892d87db > change-id: 20240824-modinfo-const-6f0d67e2b301 > > Best regards, > -- > Thomas Weißschuh <linux@xxxxxxxxxxxxxx> > -- Best Regards Masahiro Yamada
