Re: CVS commit: src/sys/arch/mips/include

[Joerg Sonnenberger <joerg%britannica.bec.de@localhost>]

On Tue, Jul 22, 2014 at 10:40:02PM +0100, Alexander Nasonov wrote:
> Matt Thomas wrote:
> > 
> > On Jul 22, 2014, at 2:27 PM, Alexander Nasonov <alnsn%yandex.ru@localhost> 
> > wrote:
> > > I allocate with the X flag and it seems to work:
> > > 
> > > /* in sljitExecAllocator.c */
> > >        return (void *)uvm_km_alloc(module_map, size,
> > >            PAGE_SIZE, UVM_KMF_WIRED | UVM_KMF_ZERO | UVM_KMF_EXEC);
> > 
> > ok.  Then you need don't a hook for cache flushing
> > 
> > pmap_protect(vm_map_pamp(module_map), va, size) will do that for you.
> > At least for arm/mips/ppc/vax.  (e.g. changing a writeable exec page
> > to read-only automatically causes it exec cleaned).
> 
> sljit allocates 64K exec chucks which are managed by a special allocator.
> You need to run pmap_protect for each chunk. I think it's cheaper to
> flush icache.

Wouldn't it be preferable to have *two* mappings for the code? One which
is writeable and another which is executable?

Joerg