Re: [PATCH] Added ability to vmalloc executable memory

[Xander <xandermoerkerken@gmail.com>]

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The pgprot parameter got removed because, according to the commit log, for
no other apparent reason than it being called with 'PAGE_KERNEL' as an
argument in the whole kernel. Therefore it got removed.
This removed the ability to allocate virtual memory with executing rights.
My use case comes from ioremap().
I think this is useful for others too.

I don't see why this pgprot parameter got removed but this is the
alternative to reverting it to the older 5.7 function.

On Fri, 9 Dec 2022 at 14:17, Mark Rutland <mark.rutland@arm.com> wrote:

> On Fri, Dec 09, 2022 at 02:10:52PM +0100, Xander Moerkerken wrote:
> > From: Xander Moerkerken <xander.moerkerken@gmail.com>
> >
> > Since release 5.8-rc1 the pgprot got removed from __vmalloc
> > because the only usage was PAGE_KERNEL as argument.
> > However, this removes the ability to input other arguments
> > such as 'PAGE_KERNEL_EXEC', which can be used to allocate
> > memory in which you can execute. For this reason a new
> > function is introduced called '__vmalloc_exec'.
> >
> > Signed-off-by: Xander Moerkerken <xander.moerkerken@omron.com>
>
> What is this going to be used for? There's no user from this patch alone,
> as a
> module or otherwise.
>
> Mark.
>
> > ---
> >  include/linux/vmalloc.h | 1 +
> >  mm/vmalloc.c            | 8 ++++++++
> >  2 files changed, 9 insertions(+)
> >
> > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> > index 096d48aa3437..10c46513b6b2 100644
> > --- a/include/linux/vmalloc.h
> > +++ b/include/linux/vmalloc.h
> > @@ -147,6 +147,7 @@ extern void *vzalloc_node(unsigned long size, int
> node) __alloc_size(1);
> >  extern void *vmalloc_32(unsigned long size) __alloc_size(1);
> >  extern void *vmalloc_32_user(unsigned long size) __alloc_size(1);
> >  extern void *__vmalloc(unsigned long size, gfp_t gfp_mask)
> __alloc_size(1);
> > +extern void *__vmalloc_exec(unsigned long size, gfp_t gfp_mask)
> __alloc_size(1);
> >  extern void *__vmalloc_node_range(unsigned long size, unsigned long
> align,
> >                       unsigned long start, unsigned long end, gfp_t
> gfp_mask,
> >                       pgprot_t prot, unsigned long vm_flags, int node,
> > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > index ccaa461998f3..8fd01ed7082b 100644
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -3294,6 +3294,14 @@ void *__vmalloc(unsigned long size, gfp_t
> gfp_mask)
> >  }
> >  EXPORT_SYMBOL(__vmalloc);
> >
> > +
> > +void *__vmalloc_exec(unsigned long size, gfp_t gfp_mask)
> > +{
> > +     return __vmalloc_node_prot(size, 1, gfp_mask, PAGE_KERNEL_EXEC,
> > +                               NUMA_NO_NODE,
> __builtin_return_address(0));
> > +}
> > +EXPORT_SYMBOL(__vmalloc_exec);
> > +
> >  /**
> >   * vmalloc - allocate virtually contiguous memory
> >   * @size:    allocation size
> > --
> > 2.37.2
> >
>

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