[PATCH 1/2] Fix the I-cache invalidation on ARMv6 and later CPUs

[Minchan Kim]

On Tue, Nov 9, 2010 at 7:38 PM, Russell King - ARM Linux
<linux at arm.linux.org.uk> wrote:
> On Tue, Nov 09, 2010 at 07:34:45PM +0900, Minchan Kim wrote:
>> On Tue, Nov 9, 2010 at 7:17 PM, Catalin Marinas <catalin.marinas at arm.com> wrote:
>> > Note that these functions are changed slightly in 2.6.37-rc1, but we
>> > still do the I-cache flushing.
>> >
>> > There reason is that the page being modified may already be mapped in
>> > user space and may be a code page as well. The kernel may call this
>>
>> Yes. That's my point. We can't know code or not in that context(ie,
>> flush_dcache_page).
>
> And because we don't know, we have to assume that the page does contain
> code, so we have to flush the I cache.
>
>> In 2.6.37-rc1, we flushes icache without VM_EXEC check in set_pte_at
>> which doesn't have VMA, either.
>> Could we move the icache flush to update_mmu_cache again?
>
> No.  We moved it to fix a race on SMP - between the PTE being established
> and the caches being coherent.  Moving it later reintroduces that race
> again.
>

Thanks, I understand the problem by your kind explanation.
So, why don't we use flush_icache_page?

page fault
read
flush_icache_page <------ here
set_pte_at
update_mmu_cache


-- 
Kind regards,
Minchan Kim