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Message-ID: <19e61a22-bbae-d0ae-8d41-158d4b46bf01@oracle.com>
Date: Fri, 11 Jan 2019 11:28:19 -0700
From: Khalid Aziz <khalid.aziz@...cle.com>
To: Tycho Andersen <tycho@...ho.ws>
Cc: juergh@...il.com, jsteckli@...zon.de, ak@...ux.intel.com,
torvalds@...ux-foundation.org, liran.alon@...cle.com,
keescook@...gle.com, konrad.wilk@...cle.com,
Juerg Haefliger <juerg.haefliger@...onical.com>,
deepa.srinivasan@...cle.com, chris.hyser@...cle.com,
tyhicks@...onical.com, dwmw@...zon.co.uk, andrew.cooper3@...rix.com,
jcm@...hat.com, boris.ostrovsky@...cle.com, kanth.ghatraju@...cle.com,
joao.m.martins@...cle.com, jmattson@...gle.com,
pradeep.vincent@...cle.com, john.haxby@...cle.com, tglx@...utronix.de,
kirill.shutemov@...ux.intel.com, hch@....de, steven.sistare@...cle.com,
kernel-hardening@...ts.openwall.com, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC PATCH v7 07/16] arm64/mm, xpfo: temporarily map dcache
regions
On 1/11/19 7:54 AM, Tycho Andersen wrote:
> On Thu, Jan 10, 2019 at 02:09:39PM -0700, Khalid Aziz wrote:
>> From: Juerg Haefliger <juerg.haefliger@...onical.com>
>>
>> If the page is unmapped by XPFO, a data cache flush results in a fatal
>> page fault, so let's temporarily map the region, flush the cache, and then
>> unmap it.
>>
>> v6: actually flush in the face of xpfo, and temporarily map the underlying
>> memory so it can be flushed correctly
>>
>> CC: linux-arm-kernel@...ts.infradead.org
>> Signed-off-by: Juerg Haefliger <juerg.haefliger@...onical.com>
>> Signed-off-by: Tycho Andersen <tycho@...ker.com>
>> Signed-off-by: Khalid Aziz <khalid.aziz@...cle.com>
>> ---
>> arch/arm64/mm/flush.c | 7 +++++++
>> 1 file changed, 7 insertions(+)
>>
>> diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c
>> index 30695a868107..f12f26b60319 100644
>> --- a/arch/arm64/mm/flush.c
>> +++ b/arch/arm64/mm/flush.c
>> @@ -20,6 +20,7 @@
>> #include <linux/export.h>
>> #include <linux/mm.h>
>> #include <linux/pagemap.h>
>> +#include <linux/xpfo.h>
>>
>> #include <asm/cacheflush.h>
>> #include <asm/cache.h>
>> @@ -28,9 +29,15 @@
>> void sync_icache_aliases(void *kaddr, unsigned long len)
>> {
>> unsigned long addr = (unsigned long)kaddr;
>> + unsigned long num_pages = XPFO_NUM_PAGES(addr, len);
>> + void *mapping[num_pages];
>
> Does this still compile with -Wvla? It was a bad hack on my part, and
> we should probably just drop it and come up with something else :)
I will make a note of it. I hope someone with better knowledge of arm64
than me can come up with a better solution ;)
--
Khalid
>
> Tycho
>
>> if (icache_is_aliasing()) {
>> + xpfo_temp_map(kaddr, len, mapping,
>> + sizeof(mapping[0]) * num_pages);
>> __clean_dcache_area_pou(kaddr, len);
>> + xpfo_temp_unmap(kaddr, len, mapping,
>> + sizeof(mapping[0]) * num_pages);
>> __flush_icache_all();
>> } else {
>> flush_icache_range(addr, addr + len);
>> --
>> 2.17.1
>>
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