Re: [PATCH v1 3/5] kbuild/modpost: integrate klp-convert

[Marcos Paulo de Souza]

On Mon, 2023-11-06 at 17:25 +0100, Lukas Hruska wrote:
> From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> 
> Update the modpost program so that it does not warn about unresolved
> symbols matching the expected format which will be then resolved by
> klp-convert.
> 
> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> Signed-off-by: Lukas Hruska <lhruska@xxxxxxx>

Reviewed-by: Marcos Paulo de Souza <mpdesouza@xxxxxxxx>

(The patch currently conflicts with Linus tree on Makefile and
modpost.c, but nothing to worry, AFAICS)

> ---
>  .gitignore                |  1 +
>  Makefile                  | 10 ++++++----
>  scripts/Makefile.modfinal | 15 +++++++++++++++
>  scripts/Makefile.modpost  |  5 +++++
>  scripts/mod/modpost.c     | 36 ++++++++++++++++++++++++++++++++++--
>  scripts/mod/modpost.h     |  3 +++
>  6 files changed, 64 insertions(+), 6 deletions(-)
> 
> diff --git a/.gitignore b/.gitignore
> index 9fd4c9533b3d..628caf76b617 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -69,6 +69,7 @@ modules.order
>  /Module.markers
>  /modules.builtin
>  /modules.builtin.modinfo
> +/modules.livepatch
>  /modules.nsdeps
>  
>  #
> diff --git a/Makefile b/Makefile
> index 2fdd8b40b7e0..459b9c9fe0a8 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1185,6 +1185,7 @@ PHONY += prepare0
>  export extmod_prefix = $(if $(KBUILD_EXTMOD),$(KBUILD_EXTMOD)/)
>  export MODORDER := $(extmod_prefix)modules.order
>  export MODULES_NSDEPS := $(extmod_prefix)modules.nsdeps
> +export MODULES_LIVEPATCH := $(extmod-prefix)modules.livepatch
>  
>  ifeq ($(KBUILD_EXTMOD),)
>  
> @@ -1535,8 +1536,8 @@ endif
>  #
>  
>  # *.ko are usually independent of vmlinux, but
> CONFIG_DEBUG_INFO_BTF_MODULES
> -# is an exception.
> -ifdef CONFIG_DEBUG_INFO_BTF_MODULES
> +# and CONFIG_LIVEPATCH are exceptions.
> +ifneq ($(or $(CONFIG_DEBUG_INFO_BTF_MODULES),$(CONFIG_LIVEPATCH)),)
>  KBUILD_BUILTIN := 1
>  modules: vmlinux
>  endif
> @@ -1595,8 +1596,9 @@ endif
>  # Directories & files removed with 'make clean'
>  CLEAN_FILES += include/ksym vmlinux.symvers modules-only.symvers \
>  	       modules.builtin modules.builtin.modinfo
> modules.nsdeps \
> -	       compile_commands.json .thinlto-cache rust/test
> rust/doc \
> -	       rust-project.json .vmlinux.objs .vmlinux.export.c
> +	       modules.livepatch compile_commandsjson .thinlto-
> cache \
> +	       rust/test rust/doc rust-project.json .vmlinux.objs \
> +	       .vmlinux.export.c
>  
>  # Directories & files removed with 'make mrproper'
>  MRPROPER_FILES += include/config include/generated          \
> diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
> index fc19f67039bd..155d07476a2c 100644
> --- a/scripts/Makefile.modfinal
> +++ b/scripts/Makefile.modfinal
> @@ -14,6 +14,7 @@ include $(srctree)/scripts/Makefile.lib
>  
>  # find all modules listed in modules.order
>  modules := $(call read-file, $(MODORDER))
> +modules-klp := $(call read-file, $(MODULES_LIVEPATCH))
>  
>  __modfinal: $(modules:%.o=%.ko)
>  	@:
> @@ -65,6 +66,20 @@ endif
>  
>  targets += $(modules:%.o=%.ko) $(modules:%.o=%.mod.o)
>  
> +# Livepatch
> +# ------------------------------------------------------------------
> ---------
> +
> +%.tmp.ko: %.o %.mod.o FORCE
> +	+$(call if_changed,ld_ko_o)
> +
> +quiet_cmd_klp_convert = KLP     $@
> +      cmd_klp_convert = scripts/livepatch/klp-convert $< $@
> +
> +$(modules-klp:%.o=%.ko): %.ko: %.tmp.ko FORCE
> +	$(call if_changed,klp_convert)
> +
> +targets += $(modules-klp:.ko=.tmp.ko)
> +
>  # Add FORCE to the prequisites of a target to force it to be always
> rebuilt.
>  # ------------------------------------------------------------------
> ---------
>  
> diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
> index 39472e834b63..c757f5eddc3e 100644
> --- a/scripts/Makefile.modpost
> +++ b/scripts/Makefile.modpost
> @@ -47,6 +47,7 @@ modpost-args
> =										\
>  	$(if $(KBUILD_MODPOST_WARN),-
> w)							\
>  	$(if $(KBUILD_NSDEPS),-d
> $(MODULES_NSDEPS))					\
>  	$(if
> $(CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS)$(KBUILD_NSDEPS),-
> N)	\
> +	$(if $(CONFIG_LIVEPATCH),-l
> $(MODULES_LIVEPATCH))				\
>  	$(if $(findstring 1, $(KBUILD_EXTRA_WARN)),-
> W)					\
>  	-o $@
>  
> @@ -144,6 +145,10 @@ $(output-symdump): $(modpost-deps) FORCE
>  	$(call if_changed,modpost)
>  
>  __modpost: $(output-symdump)
> +ifndef CONFIG_LIVEPATCH
> +	$(Q)rm -f $(MODULES_LIVEPATCH)
> +	$(Q)touch $(MODULES_LIVEPATCH)
> +endif
>  PHONY += FORCE
>  FORCE:
>  
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index b29b29707f10..f6afa2e10601 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -1733,6 +1733,10 @@ static void read_symbols(const char *modname)
>  		}
>  	}
>  
> +	/* Livepatch modules have unresolved symbols resolved by
> klp-convert */
> +	if (get_modinfo(&info, "livepatch"))
> +		mod->is_livepatch = true;
> +
>  	if (extra_warn && !get_modinfo(&info, "description"))
>  		warn("missing MODULE_DESCRIPTION() in %s\n",
> modname);
>  	for (sym = info.symtab_start; sym < info.symtab_stop; sym++)
> {
> @@ -1821,10 +1825,18 @@ static void check_exports(struct module *mod)
>  		const char *basename;
>  		exp = find_symbol(s->name);
>  		if (!exp) {
> -			if (!s->weak && nr_unresolved++ <
> MAX_UNRESOLVED_REPORTS)
> +			if (!s->weak && nr_unresolved++ <
> MAX_UNRESOLVED_REPORTS) {
> +				/*
> +				 * In case of livepatch module we
> allow
> +				 * unresolved symbol with a specific
> format
> +				 */
> +				if (mod->is_livepatch &&
> +				    strncmp(s->name, KLP_SYM_RELA,
> strlen(KLP_SYM_RELA)) == 0)
> +					break;
>  				modpost_log(warn_unresolved ?
> LOG_WARN : LOG_ERROR,
>  					    "\"%s\" [%s.ko]
> undefined!\n",
>  					    s->name, mod->name);
> +			}
>  			continue;
>  		}
>  		if (exp->module == mod) {
> @@ -2257,6 +2269,20 @@ static void write_namespace_deps_files(const
> char *fname)
>  	free(ns_deps_buf.p);
>  }
>  
> +static void write_livepatch_modules(const char *fname)
> +{
> +	struct buffer buf = { };
> +	struct module *mod;
> +
> +	list_for_each_entry(mod, &modules, list) {
> +		if (mod->is_livepatch)
> +			buf_printf(&buf, "%s.o\n", mod->name);
> +	}
> +
> +	write_if_changed(&buf, fname);
> +	free(buf.p);
> +}
> +
>  struct dump_list {
>  	struct list_head list;
>  	const char *file;
> @@ -2268,11 +2294,12 @@ int main(int argc, char **argv)
>  	char *missing_namespace_deps = NULL;
>  	char *unused_exports_white_list = NULL;
>  	char *dump_write = NULL, *files_source = NULL;
> +	char *livepatch_modules = NULL;
>  	int opt;
>  	LIST_HEAD(dump_lists);
>  	struct dump_list *dl, *dl2;
>  
> -	while ((opt = getopt(argc, argv, "ei:mnT:to:au:WwENd:")) !=
> -1) {
> +	while ((opt = getopt(argc, argv, "ei:l:mnT:to:au:WwENd:"))
> != -1) {
>  		switch (opt) {
>  		case 'e':
>  			external_module = true;
> @@ -2282,6 +2309,9 @@ int main(int argc, char **argv)
>  			dl->file = optarg;
>  			list_add_tail(&dl->list, &dump_lists);
>  			break;
> +		case 'l':
> +			livepatch_modules = optarg;
> +			break;
>  		case 'm':
>  			modversions = true;
>  			break;
> @@ -2361,6 +2391,8 @@ int main(int argc, char **argv)
>  
>  	if (dump_write)
>  		write_dump(dump_write);
> +	if (livepatch_modules)
> +		write_livepatch_modules(livepatch_modules);
>  	if (sec_mismatch_count && !sec_mismatch_warn_only)
>  		error("Section mismatches detected.\n"
>  		      "Set CONFIG_SECTION_MISMATCH_WARN_ONLY=y to
> allow them.\n");
> diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
> index dfdb9484e325..7cb8d604d739 100644
> --- a/scripts/mod/modpost.h
> +++ b/scripts/mod/modpost.h
> @@ -98,6 +98,8 @@ static inline void __endian(const void *src, void
> *dest, unsigned int size)
>  
>  #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
>  
> +#define KLP_SYM_RELA ".klp.sym.rela."
> +
>  void *do_nofail(void *ptr, const char *expr);
>  
>  struct buffer {
> @@ -119,6 +121,7 @@ struct module {
>  	bool is_gpl_compatible;
>  	bool from_dump;		/* true if module was loaded
> from *.symvers */
>  	bool is_vmlinux;
> +	bool is_livepatch;
>  	bool seen;
>  	bool has_init;
>  	bool has_cleanup;