Re: [PATCH v4 05/15] mm: introduce execmem_alloc() and execmem_free()

Mike Rapoport
2024-04-14T06:55:25Z

On Thu, Apr 11, 2024 at 12:42:05PM -0700, Luis Chamberlain wrote:
> On Thu, Apr 11, 2024 at 07:00:41PM +0300, Mike Rapoport wrote:
> > From: "Mike Rapoport (IBM)" <rppt@kernel.org>
> >
> > module_alloc() is used everywhere as a mean to allocate memory for code.
> >
> > Beside being semantically wrong, this unnecessarily ties all subsystems
> > that need to allocate code, such as ftrace, kprobes and BPF to modules and
> > puts the burden of code allocation to the modules code.
> >
> > Several architectures override module_alloc() because of various
> > constraints where the executable memory can be located and this causes
> > additional obstacles for improvements of code allocation.
> >
> > Start splitting code allocation from modules by introducing execmem_alloc()
> > and execmem_free() APIs.
> >
> > Initially, execmem_alloc() is a wrapper for module_alloc() and
> > execmem_free() is a replacement of module_memfree() to allow updating all
> > call sites to use the new APIs.
> >
> > Since architectures define different restrictions on placement,
> > permissions, alignment and other parameters for memory that can be used by
> > different subsystems that allocate executable memory, execmem_alloc() takes
> > a type argument, that will be used to identify the calling subsystem and to
> > allow architectures define parameters for ranges suitable for that
> > subsystem.
>
> It would be good to describe this is a non-fuctional change.

Ok.

> > Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
> > ---
>
> > diff --git a/mm/execmem.c b/mm/execmem.c
> > new file mode 100644
> > index 000000000000..ed2ea41a2543
> > --- /dev/null
> > +++ b/mm/execmem.c
> > @@ -0,0 +1,26 @@
> > +// SPDX-License-Identifier: GPL-2.0
>
> And this just needs to copy over the copyright notices from the main.c file.

Will do.

> Luis

--
Sincerely yours,
Mike.