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 <[email protected]>
> > Cc: Andreas Hindborg <[email protected]>
> > Cc: Danilo Krummrich <[email protected]>
> > Cc: Alex Gaynor <[email protected]>
> > Cc: [email protected]
> > Signed-off-by: Alexey Gladkov <[email protected]>
> > ---
> > 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.
>
> > + "__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
