From: Daniel Axtens <dja@axtens.net>
To: Christophe Leroy <christophe.leroy@c-s.fr>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
linux-xtensa@linux-xtensa.org, linux-arch@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, kasan-dev@googlegroups.com,
aneesh.kumar@linux.ibm.com, bsingharora@gmail.com
Subject: Re: [PATCH v2 4/4] powerpc: Book3S 64-bit "heavyweight" KASAN support
Date: Fri, 13 Dec 2019 00:41:14 +1100 [thread overview]
Message-ID: <87tv65br0l.fsf@dja-thinkpad.axtens.net> (raw)
In-Reply-To: <414293e0-3b75-8e78-90d8-2c14182f3739@c-s.fr>
Hi Christophe,
I think I've covered everything you've mentioned in the v3 I'm about to
send, except for:
>> + /* mark early shadow region as RO and wipe */
>> + pte = __pte(__pa(kasan_early_shadow_page) |
>> + pgprot_val(PAGE_KERNEL_RO) | _PAGE_PTE);
>
> Any reason for _PAGE_PTE being required here and not being included in
> PAGE_KERNEL_RO ?
I'm not 100% sure quite what you mean here. I think you're asking: why
do we need to supply _PAGE_PTE here, shouldn't PAGE_KERNEL_RO set that
bit or cover that case?
_PAGE_PTE is defined by section 5.7.10.2 of Book III of ISA 3.0: bit 1
(linux bit 62) is 'Leaf (entry is a PTE)' I originally had this because
it was set in Balbir's original implementation, but the bit is also set
by pte_mkpte which is called in set_pte_at, so I also think it's right
to set it.
I don't know why it's not included in the permission classes; I suspect
it's because it's not conceptually a permission, it's set and cleared in
things like swp entry code.
Does that answer your question?
Regards,
Daniel
next prev parent reply other threads:[~2019-12-12 13:41 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-10 4:47 [PATCH v2 0/4] KASAN for powerpc64 radix, plus generic mm change Daniel Axtens
2019-12-10 4:47 ` [PATCH v2 1/4] mm: define MAX_PTRS_PER_{PTE,PMD,PUD} Daniel Axtens
2019-12-10 6:35 ` Christophe Leroy
2019-12-10 9:35 ` Balbir Singh
2019-12-10 10:39 ` kbuild test robot
2019-12-10 4:47 ` [PATCH v2 2/4] kasan: use MAX_PTRS_PER_* for early shadow Daniel Axtens
2019-12-10 6:40 ` Christophe Leroy
2019-12-10 9:36 ` Balbir Singh
2019-12-10 14:39 ` Christophe Leroy
2019-12-10 4:47 ` [PATCH v2 3/4] kasan: Document support on 32-bit powerpc Daniel Axtens
2019-12-10 6:40 ` Christophe Leroy
2019-12-10 4:47 ` [PATCH v2 4/4] powerpc: Book3S 64-bit "heavyweight" KASAN support Daniel Axtens
2019-12-10 7:21 ` Christophe Leroy
2019-12-12 13:41 ` Daniel Axtens [this message]
2019-12-10 10:57 ` Balbir Singh
2019-12-11 5:21 ` Daniel Axtens
2019-12-11 8:57 ` Balbir Singh
2019-12-11 14:24 ` Daniel Axtens
2019-12-12 7:42 ` Balbir Singh
2019-12-12 9:38 ` Christophe Leroy
2019-12-12 9:56 ` Andrey Ryabinin
2019-12-10 11:20 ` kbuild test robot
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