Re: [RFC 2/3] arm: mm: Define set_memory_* functions for ARM

[Will Deacon <will.deacon@arm.com>]

On Wed, Jun 19, 2013 at 02:48:28AM +0100, Laura Abbott wrote:
> On 6/18/2013 4:09 AM, Will Deacon wrote:
> > On Wed, Jun 12, 2013 at 06:23:29PM +0100, Laura Abbott wrote:
> >> Other architectures define various set_memory functions to allow
> >> attributes to be changed (e.g. set_memory_x, set_memory_rw, etc.)
> >> Currently, these functions are missing on ARM. Define these in an
> >> appropriate manner for ARM.
> >>
> >> Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
> >> ---
> >>   arch/arm/include/asm/cacheflush.h |    5 ++
> >>   arch/arm/mm/mmu.c                 |   86 +++++++++++++++++++++++++++++++++++++
> >>   2 files changed, 91 insertions(+), 0 deletions(-)
> >>
> >> diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h
> >> index bff7138..55ed26b 100644
> >> --- a/arch/arm/include/asm/cacheflush.h
> >> +++ b/arch/arm/include/asm/cacheflush.h
> >> @@ -438,4 +438,9 @@ static inline void __sync_cache_range_r(volatile void *p, size_t size)
> >>   #define sync_cache_w(ptr) __sync_cache_range_w(ptr, sizeof *(ptr))
> >>   #define sync_cache_r(ptr) __sync_cache_range_r(ptr, sizeof *(ptr))
> >>
> >> +int set_memory_ro(unsigned long addr, int numpages);
> >> +int set_memory_rw(unsigned long addr, int numpages);
> >> +int set_memory_x(unsigned long addr, int numpages);
> >> +int set_memory_nx(unsigned long addr, int numpages);
> >
> > This seems like a pretty clunky interface with a horribly generic name, but
> > that seems to be what x86 and s390 are using. I wonder if there would be any
> > interest in tidying it up a bit? It really looks like something that is
> > x86-specific but has started to grow users in core code (set_memory_4k?!).
> >
> 
> I think cleanup would be beneficial. Nothing else really uses the 
> set_memory_* functions and s390 explicitly defined them so they could 
> use CONFIG_DEBUG_SET_MODULE_RONX as well. Perhaps the work I did with 
> apply_to_page_range could apply across all architectures?

It's certainly worth a look, and would probably warrant changing the
function prototypes to take the size rather than the number of pages too.

Will