On Thu Aug 14, 2025 at 3:54 PM CEST, Alexey Gladkov wrote:
> On Thu, Aug 14, 2025 at 03:26:53PM +0200, Danilo Krummrich wrote:
>> On Thu Aug 14, 2025 at 3:07 PM CEST, Alexey Gladkov wrote:
>> > At this point, if a symbol is compiled as part of the kernel,
>> > information about which module the symbol belongs to is lost.
>> >
>> > To save this it is possible to add the module name to the alias name.
>> > It's not very pretty, but it's possible for now.
>> >
>> > Cc: Miguel Ojeda <oj...@kernel.org>
>> > Cc: Andreas Hindborg <a.hindb...@kernel.org>
>> > Cc: Danilo Krummrich <d...@kernel.org>
>> > Cc: Alex Gaynor <alex.gay...@gmail.com>
>> > Cc: rust-for-li...@vger.kernel.org
>> > Signed-off-by: Alexey Gladkov <leg...@kernel.org>
>> > ---
>> > include/linux/module.h | 14 +++++++++++++-
>> > rust/kernel/device_id.rs | 8 ++++----
>> > scripts/mod/file2alias.c | 18 ++++++++++++++----
>> > 3 files changed, 31 insertions(+), 9 deletions(-)
>> >
>> > diff --git a/include/linux/module.h b/include/linux/module.h
>> > index 3319a5269d28..e31ee29fac6b 100644
>> > --- a/include/linux/module.h
>> > +++ b/include/linux/module.h
>> > @@ -244,10 +244,22 @@ struct module_kobject
>> > *lookup_or_create_module_kobject(const char *name);
>> > /* What your module does. */
>> > #define MODULE_DESCRIPTION(_description) MODULE_INFO(description,
>> > _description)
>> >
>> > +/*
>> > + * Format: __mod_device_table__kmod_<modname>__<type>__<name>
>> > + * Parts of the string `__kmod_` and `__` are used as delimiters when
>> > parsing
>> > + * a symbol in file2alias.c
>> > + */
>> > +#define __mod_device_table(type, name) \
>> > + __PASTE(__mod_device_table__, \
>> > + __PASTE(__KBUILD_MODNAME, \
>> > + __PASTE(__, \
>> > + __PASTE(type, \
>> > + __PASTE(__, name)))))
>> > +
>> > #ifdef MODULE
>> > /* Creates an alias so file2alias.c can find device table. */
>> > #define MODULE_DEVICE_TABLE(type, name)
>> > \
>> > -static typeof(name) __mod_device_table__##type##__##name \
>> > +static typeof(name) __mod_device_table(type, name)
>> > \
>> > __attribute__ ((used, alias(__stringify(name))))
>> > #else /* !MODULE */
>> > #define MODULE_DEVICE_TABLE(type, name)
>> > diff --git a/rust/kernel/device_id.rs b/rust/kernel/device_id.rs
>> > index 70d57814ff79..62c42da12e9d 100644
>> > --- a/rust/kernel/device_id.rs
>> > +++ b/rust/kernel/device_id.rs
>> > @@ -195,10 +195,10 @@ macro_rules! module_device_table {
>> > ($table_type: literal, $module_table_name:ident, $table_name:ident)
>> > => {
>> > #[rustfmt::skip]
>> > #[export_name =
>> > - concat!("__mod_device_table__", $table_type,
>> > - "__", module_path!(),
>> > - "_", line!(),
>> > - "_", stringify!($table_name))
>> > + concat!("__mod_device_table__", line!(),
>>
>> Why do we have line!() between "__mod_device_table__" and "__kmod_", while
>> the
>> format is defined as "__mod_device_table__kmod_<modname>__<type>__<name>"
>> above?
>
> The "__mod_device_table__" is used to filter symbols.
> The meaning part starts after "__kmod_" part. After that, order becomes
> important.
>
>> The previous logic was to create a unique name with
>> using "<module_path>_<line>_<table_name>" as "<name>". So, I think this
>> should
>> actually be:
>>
>> concat!("__mod_device_table__kmod_",
>> module_path!(),
>> "__", $table_type,
>> "__", stringify!($table_name),
>> "_", line!())
>>
>> rather than the below.
>
> No. "stringify!($table_name)" should be the last thing in this string.
> This is the a symbol name that will be searched for in the elf to generate
> modalias.
$table_name is not guaranteed to be unique for a certain module_path!(), hence
we need line!() to guarantee uniqueness.
The symbol name will be unique no matter where you place line!() of course, but
$table_name + line!() is the unique table name, which I think is what we want?
>>
>> > + "__kmod_", module_path!(),
>> > + "__", $table_type,
>> > + "__", stringify!($table_name))
>> > ]
>> > static $module_table_name: [::core::mem::MaybeUninit<u8>;
>> > $table_name.raw_ids().size()] =
>> > unsafe { ::core::mem::transmute_copy($table_name.raw_ids()) };
>>
>
> --
> Rgrds, legion
