Implement MODULE_DEVICE_TABLE for build-in modules to make it possible to generate a builtin.alias file to complement modules.alias. Signed-off-by: Allen Webb <allenwebb@xxxxxxxxxx> --- include/linux/module.h | 36 +++++++++++++++++++++++++++++------- 1 file changed, 29 insertions(+), 7 deletions(-) diff --git a/include/linux/module.h b/include/linux/module.h index 4435ad9439ab..b1cb12e06996 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -237,14 +237,36 @@ extern void cleanup_module(void); /* What your module does. */ #define MODULE_DESCRIPTION(_description) MODULE_INFO(description, _description) -#ifdef MODULE -/* Creates an alias so file2alias.c can find device table. */ +/* + * Creates an alias so file2alias.c can find device table. + * + * Use this in cases where a device table is used to match devices because it + * surfaces match-id based module aliases to userspace for: + * - Automatic module loading through modules.alias. + * - Tools like USBGuard which block devices based on policy such as which + * modules match a device. + * + * The only use-case for built-in drivers today is to enable userspace to + * prevent / allow probe for devices on certain subsystems even if the driver is + * already loaded. An example is the USB subsystem with its authorized_default + * sysfs attribute. For more details refer to the kernel's Documentation for USB + * about authorized_default. + * + * The module name is included in the alias for two reasons: + * - It avoids creating two aliases with the same name for built-in modules. + * Historically MODULE_DEVICE_TABLE was a no-op for built-in modules, so + * there was nothing to stop different modules from having the same device + * table name and consequently the same alias when building as a module. + * - The module name is needed by files2alias.c to associate a particular + * device table with its associated module for built-in modules since + * files2alias would otherwise see the module name as `vmlinuz.o`. + */ #define MODULE_DEVICE_TABLE(type, name) \ -extern typeof(name) __mod_##type##__##name##_device_table \ - __attribute__ ((unused, alias(__stringify(name)))) -#else /* !MODULE */ -#define MODULE_DEVICE_TABLE(type, name) -#endif +extern void *CONCATENATE( \ + CONCATENATE(__mod_##type##__##name##__, \ + __KBUILD_MODNAME), \ + _device_table) \ + __attribute__ ((unused, alias(__stringify(name)))) /* Version of form [<epoch>:]<version>[-<extra-version>]. * Or for CVS/RCS ID version, everything but the number is stripped. -- 2.39.2
