On 4/26/25 18:16, 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>
> ---
> include/linux/module.h | 4 ----
> scripts/mod/file2alias.c | 13 ++++++++++++-
> scripts/mod/modpost.c | 21 ++++++++++++++++++---
> scripts/mod/modpost.h | 7 ++++++-
> 4 files changed, 36 insertions(+), 9 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..0fa3f031b904 100644
> --- a/scripts/mod/file2alias.c
> +++ b/scripts/mod/file2alias.c
> @@ -1471,7 +1471,8 @@ static const struct devtable devtable[] = {
> /* Create MODULE_ALIAS() statements.
> * At this time, we cannot write the actual output C source yet,
> * so we write into the mod->dev_table_buf buffer. */
> -void handle_moddevtable(struct module *mod, struct elf_info *info,
> +void handle_moddevtable(struct list_head *modules,
> + struct module *mod, struct elf_info *info,
> Elf_Sym *sym, const char *symname)
> {
> void *symval;
The new modules parameter is unused.
> @@ -1509,6 +1510,16 @@ void handle_moddevtable(struct module *mod, struct
> elf_info *info,
> typelen = name - type;
> name += strlen("__");
>
> + if (mod->is_vmlinux) {
> + struct module *builtin_mod;
> +
> + builtin_mod = new_module(modname, modnamelen);
> + builtin_mod->is_vmlinux = mod->is_vmlinux;
> + builtin_mod->dump_file = MODULE_BUILTIN_FNAME;
The module.dump_file member is described in scripts/mod/modpost.h as
"path to the .symvers file if loaded from a file". However, that is not
the case here.
Similarly, the module struct in scripts/mod/modpost.h is commented as
"represent a module (vmlinux or *.ko)", but this patch expands its scope
to also include builtin modules.
I'm not sure it's best to overload this data in this way. I think mixing
actual files and "logical" modules in the modules list is somewhat
confusing.
An alternative would be to keep a single module struct for vmlinux and
record the discovered aliases under it?
--
Thanks,
Petr
