On Mon, May 05, 2025 at 11:38:29AM +0200, Alexey Gladkov wrote:
> For some modules, modalias is generated using the modpost utility and
> the section is added to the module file.
>
> When a module is added inside vmlinux, modpost does not generate
> modalias for such modules and the information is lost.
>
> As a result kmod (which uses modules.builtin.modinfo in userspace)
> cannot determine that modalias is handled by a builtin kernel module.
>
> $ cat /sys/devices/pci0000:00/0000:00:14.0/modalias
> pci:v00008086d0000A36Dsv00001043sd00008694bc0Csc03i30
>
> $ modinfo xhci_pci
> name: xhci_pci
> filename: (builtin)
> license: GPL
> file: drivers/usb/host/xhci-pci
> description: xHCI PCI Host Controller Driver
>
> Missing modalias "pci:v*d*sv*sd*bc0Csc03i30*" which will be generated by
> modpost if the module is built separately.
>
> To fix this it is necessary to generate the same modalias for vmlinux as
> for the individual modules. Fortunately '.vmlinux.export.o' is already
> generated from which '.modinfo' can be extracted in the same way as for
> vmlinux.o.
>
> Signed-off-by: Alexey Gladkov <leg...@kernel.org>
> ---
>
> v2: As Petr Pavlu suggested, I separated the builtin modules from the external
> modules. I've also added a search for duplicate modules.
>
> ---
> include/linux/module.h | 4 ----
> scripts/mod/file2alias.c | 5 +++++
> scripts/mod/modpost.c | 35 +++++++++++++++++++++++++++--------
> scripts/mod/modpost.h | 15 ++++++++++++++-
> 4 files changed, 46 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/module.h b/include/linux/module.h
> index 7250b4a527ec..6225793ddcd4 100644
> --- a/include/linux/module.h
> +++ b/include/linux/module.h
> @@ -257,14 +257,10 @@ extern void cleanup_module(void);
> __PASTE(type, \
> __PASTE(__, name)))))))
>
> -#ifdef MODULE
> /* Creates an alias so file2alias.c can find device table. */
> #define MODULE_DEVICE_TABLE(type, name) \
> extern typeof(name) __mod_device_table(type, name) \
> __attribute__ ((unused, alias(__stringify(name))))
> -#else /* !MODULE */
> -#define MODULE_DEVICE_TABLE(type, name)
> -#endif
>
> /* Version of form [<epoch>:]<version>[-<extra-version>].
> * Or for CVS/RCS ID version, everything but the number is stripped.
> diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
> index dff1799a4c79..be221923f582 100644
> --- a/scripts/mod/file2alias.c
> +++ b/scripts/mod/file2alias.c
> @@ -1509,6 +1509,11 @@ void handle_moddevtable(struct module *mod, struct
> elf_info *info,
> typelen = name - type;
> name += strlen("__");
>
> + if (mod->is_vmlinux) {
> + mod = find_module(NULL, modname, modnamelen);
> + mod = mod ?: new_builtin_module(modname, modnamelen);
> + }
> +
> /* Handle all-NULL symbols allocated into .bss */
> if (info->sechdrs[get_secindex(info, sym)].sh_type & SHT_NOBITS) {
> zeros = calloc(1, sym->st_size);
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index be89921d60b6..db3c172d4528 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -168,22 +168,26 @@ char *get_line(char **stringp)
> return orig;
> }
>
> -/* A list of all modules we processed */
> +/* A list of all modules (vmlinux or *.ko) we processed */
> LIST_HEAD(modules);
>
> -static struct module *find_module(const char *filename, const char *modname)
> +/* A list of all builtin modules we processed */
> +LIST_HEAD(builtin_modules);
> +
> +struct module *find_module(const char *filename, const char *name, size_t
> namelen)
> {
> struct module *mod;
>
> list_for_each_entry(mod, &modules, list) {
> - if (!strcmp(mod->dump_file, filename) &&
> - !strcmp(mod->name, modname))
> + if ((mod->dump_file && !strcmp(mod->dump_file, filename)) &&
> + namelen != strlen(mod->name) &&
Of course there has to be an '==' here. I'll fix it if this patch fits.
> + !strncmp(mod->name, name, namelen))
> return mod;
> }
> return NULL;
> }
>
> -static struct module *new_module(const char *name, size_t namelen)
> +struct module *create_module(const char *name, size_t namelen, bool
> is_builtin)
> {
> struct module *mod;
>
> @@ -207,7 +211,10 @@ static struct module *new_module(const char *name,
> size_t namelen)
> */
> mod->is_gpl_compatible = true;
>
> - list_add_tail(&mod->list, &modules);
> + if (is_builtin)
> + list_add_tail(&mod->list, &builtin_modules);
> + else
> + list_add_tail(&mod->list, &modules);
>
> return mod;
> }
> @@ -2021,11 +2028,23 @@ static void write_if_changed(struct buffer *b, const
> char *fname)
> static void write_vmlinux_export_c_file(struct module *mod)
> {
> struct buffer buf = { };
> + struct module_alias *alias, *next;
>
> buf_printf(&buf,
> - "#include <linux/export-internal.h>\n");
> + "#include <linux/export-internal.h>\n"
> + "#include <linux/module.h>\n");
>
> add_exported_symbols(&buf, mod);
> +
> + list_for_each_entry(mod, &builtin_modules, list) {
> + list_for_each_entry_safe(alias, next, &mod->aliases, node) {
> + buf_printf(&buf, "MODULE_ALIAS_MODNAME(\"%s\",
> \"%s\");\n",
> + mod->name, alias->str);
> + list_del(&alias->node);
> + free(alias);
> + }
> + }
> +
> write_if_changed(&buf, ".vmlinux.export.c");
> free(buf.p);
> }
> @@ -2112,7 +2131,7 @@ static void read_dump(const char *fname)
> continue;
> }
>
> - mod = find_module(fname, modname);
> + mod = find_module(fname, modname, strlen(modname));
> if (!mod) {
> mod = new_module(modname, strlen(modname));
> mod->dump_file = fname;
> diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
> index 9133e4c3803f..1d0dd4ee944a 100644
> --- a/scripts/mod/modpost.h
> +++ b/scripts/mod/modpost.h
> @@ -107,7 +107,7 @@ struct module_alias {
> };
>
> /**
> - * struct module - represent a module (vmlinux or *.ko)
> + * struct module - represent a module (vmlinux, a builtin module, or *.ko)
> *
> * @dump_file: path to the .symvers file if loaded from a file
> * @aliases: list head for module_aliases
> @@ -199,6 +199,19 @@ static inline bool is_valid_name(struct elf_info *elf,
> Elf_Sym *sym)
> return !is_mapping_symbol(name);
> }
>
> +struct module *find_module(const char *filename, const char *name, size_t
> namelen);
> +struct module *create_module(const char *name, size_t namelen, bool
> is_builtin);
> +
> +static inline struct module *new_module(const char *name, size_t namelen)
> +{
> + return create_module(name, namelen, false);
> +}
> +
> +static inline struct module *new_builtin_module(const char *name, size_t
> namelen)
> +{
> + return create_module(name, namelen, true);
> +}
> +
> /* symsearch.c */
> void symsearch_init(struct elf_info *elf);
> void symsearch_finish(struct elf_info *elf);
> --
> 2.49.0
>
--
Rgrds, legion
