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

[Matt Thomas <matt%3am-software.com@localhost>]

On Jul 22, 2014, at 2:27 PM, Alexander Nasonov <alnsn%yandex.ru@localhost> 
wrote:

> Matt Thomas wrote:
>> 
>> On Jul 22, 2014, at 12:54 PM, Alexander Nasonov <alnsn%netbsd.org@localhost> 
>> wrote:
>> 
>>> Module Name:        src
>>> Committed By:       alnsn
>>> Date:               Tue Jul 22 19:54:55 UTC 2014
>>> 
>>> Modified Files:
>>>     src/sys/arch/mips/include: sljitarch.h
>>> 
>>> Log Message:
>>> Define SLJIT_CACHE_FLUSH() for mips.
>> 
>> Actually, this isn't enough.  You need to allocate a page of mapped
>> memory as RWX and then when you are done use pmap_protect to change
>> it to RX followed by pmap_update() and the pmap will automagically
>> sync the page for you.
> 
> 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).