From: Mark Rutland <mark.rutland@arm.com>
To: Tycho Andersen <tycho@docker.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
kernel-hardening@lists.openwall.com,
Marco Benatto <marco.antonio.780@gmail.com>,
Juerg Haefliger <juerg.haefliger@canonical.com>,
Juerg Haefliger <juerg.haefliger@hpe.com>
Subject: Re: [kernel-hardening] [PATCH v5 07/10] arm64/mm: Don't flush the data cache if the page is unmapped by XPFO
Date: Sat, 12 Aug 2017 12:57:37 +0100 [thread overview]
Message-ID: <20170812115736.GC16374@remoulade> (raw)
In-Reply-To: <20170809200755.11234-8-tycho@docker.com>
On Wed, Aug 09, 2017 at 02:07:52PM -0600, Tycho Andersen wrote:
> From: Juerg Haefliger <juerg.haefliger@hpe.com>
>
> If the page is unmapped by XPFO, a data cache flush results in a fatal
> page fault. So don't flush in that case.
Do you have an example callchain where that happens? We might need to shuffle
things around to cater for that case.
> @@ -30,7 +31,9 @@ void sync_icache_aliases(void *kaddr, unsigned long len)
> unsigned long addr = (unsigned long)kaddr;
>
> if (icache_is_aliasing()) {
> - __clean_dcache_area_pou(kaddr, len);
> + /* Don't flush if the page is unmapped by XPFO */
> + if (!xpfo_page_is_unmapped(virt_to_page(kaddr)))
> + __clean_dcache_area_pou(kaddr, len);
> __flush_icache_all();
> } else {
> flush_icache_range(addr, addr + len);
I don't think this patch is correct. If data cache maintenance is required in
the absence of XPFO, I don't see why it wouldn't be required in the presence of
XPFO.
I'm not immediately sure why the non-aliasing case misses data cache
maintenance. I couldn't spot where that happens otherwise.
On a more general note, in future it would be good to Cc the arm64 maintainers
and the linux-arm-kernel mailing list for patches affecting arm64.
Thanks,
Mark.
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next prev parent reply other threads:[~2017-08-12 11:57 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-09 20:07 [PATCH v5 00/10] Add support for eXclusive Page Frame Ownership Tycho Andersen
2017-08-09 20:07 ` [PATCH v5 01/10] mm: add MAP_HUGETLB support to vm_mmap Tycho Andersen
2017-08-09 20:07 ` [PATCH v5 02/10] mm, x86: Add support for eXclusive Page Frame Ownership (XPFO) Tycho Andersen
2017-08-14 18:51 ` Laura Abbott
2017-08-14 22:30 ` Laura Abbott
2017-08-15 3:47 ` Tycho Andersen
2017-08-15 3:51 ` Tycho Andersen
2017-08-09 20:07 ` [PATCH v5 03/10] swiotlb: Map the buffer if it was unmapped by XPFO Tycho Andersen
2017-08-10 13:01 ` Konrad Rzeszutek Wilk
2017-08-10 16:22 ` Tycho Andersen
2017-09-20 16:19 ` Dave Hansen
2017-09-20 22:47 ` Tycho Andersen
2017-09-20 23:25 ` Dave Hansen
2017-08-09 20:07 ` [PATCH v5 04/10] arm64: Add __flush_tlb_one() Tycho Andersen
2017-08-12 11:26 ` [kernel-hardening] " Mark Rutland
2017-08-14 16:35 ` Tycho Andersen
2017-08-14 16:50 ` Mark Rutland
2017-08-14 17:01 ` Tycho Andersen
2017-08-23 16:58 ` Tycho Andersen
2017-08-23 17:04 ` Mark Rutland
2017-08-23 17:13 ` Tycho Andersen
2017-08-24 15:45 ` Mark Rutland
2017-08-29 17:24 ` Tycho Andersen
2017-08-30 5:31 ` Juerg Haefliger
2017-08-30 16:47 ` Tycho Andersen
2017-08-31 9:43 ` Juerg Haefliger
2017-08-31 9:47 ` Mark Rutland
2017-08-31 21:21 ` Tycho Andersen
2017-08-09 20:07 ` [PATCH v5 05/10] arm64/mm: Add support for XPFO Tycho Andersen
2017-08-11 18:01 ` [kernel-hardening] " Laura Abbott
2017-08-11 20:19 ` Tycho Andersen
2017-08-09 20:07 ` [PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled Tycho Andersen
2017-08-11 17:25 ` [kernel-hardening] " Laura Abbott
2017-08-11 21:13 ` Tycho Andersen
2017-08-11 21:52 ` Tycho Andersen
2017-08-12 11:17 ` Mark Rutland
2017-08-14 16:22 ` Tycho Andersen
2017-08-14 18:42 ` Laura Abbott
2017-08-14 20:28 ` Tycho Andersen
2017-08-09 20:07 ` [PATCH v5 07/10] arm64/mm: Don't flush the data cache if the page is unmapped by XPFO Tycho Andersen
2017-08-12 11:57 ` Mark Rutland [this message]
2017-08-14 16:54 ` [kernel-hardening] " Mark Rutland
2017-08-14 20:27 ` Tycho Andersen
2017-08-15 9:39 ` Mark Rutland
2017-08-09 20:07 ` [PATCH v5 08/10] arm64/mm: Add support for XPFO to swiotlb Tycho Andersen
2017-08-10 13:11 ` Konrad Rzeszutek Wilk
2017-08-10 16:35 ` Tycho Andersen
2017-08-09 20:07 ` [PATCH v5 09/10] mm: add a user_virt_to_phys symbol Tycho Andersen
2017-08-09 20:07 ` [PATCH v5 10/10] lkdtm: Add test for XPFO Tycho Andersen
2017-08-12 20:24 ` kbuild test robot
2017-08-14 16:21 ` Tycho Andersen
2017-08-12 21:05 ` kbuild test robot
2017-08-14 19:10 ` Kees Cook
2017-08-14 20:29 ` Tycho Andersen
2017-08-11 23:35 ` [kernel-hardening] [PATCH v5 00/10] Add support for eXclusive Page Frame Ownership Laura Abbott
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