From: Daniel Axtens <dja@axtens.net>
To: Balbir Singh <bsingharora@gmail.com>
Cc: aneesh.kumar@linux.ibm.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, kasan-dev@googlegroups.com,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v11 6/6] powerpc: Book3S 64-bit outline-only KASAN support
Date: Mon, 22 Mar 2021 16:52:00 +1100 [thread overview]
Message-ID: <87lfafburj.fsf@dja-thinkpad.axtens.net> (raw)
In-Reply-To: <20210322025934.GG77072@balbir-desktop>
Balbir Singh <bsingharora@gmail.com> writes:
> On Mon, Mar 22, 2021 at 11:55:08AM +1100, Daniel Axtens wrote:
>> Hi Balbir,
>>
>> > Could you highlight the changes from
>> > https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20170729140901.5887-1-bsingharora@gmail.com/?
>> >
>> > Feel free to use my signed-off-by if you need to and add/update copyright
>> > headers if appropriate.
>>
>> There's not really anything in common any more:
>>
>> - ppc32 KASAN landed, so there was already a kasan.h for powerpc, the
>> explicit memcpy changes, the support for non-instrumented files,
>> prom_check.sh, etc. all already landed.
>>
>> - I locate the shadow region differently and don't resize any virtual
>> memory areas.
>>
>> - The ARCH_DEFINES_KASAN_ZERO_PTE handling changed upstream and our
>> handling for that is now handled more by patch 3.
>>
>> - The outline hook is now an inline function rather than a #define.
>>
>> - The init function has been totally rewritten as it's gone from
>> supporting real mode to not supporting real mode and back.
>>
>> - The list of non-instrumented files has grown a lot.
>>
>> - There's new stuff: stack walking is now safe, KASAN vmalloc support
>> means modules are better supported now, ptdump works, and there's
>> documentation.
>>
>> It's been a while now, but I don't think when I started this process 2
>> years ago that I directly reused much of your code. So I'm not sure that
>> a signed-off-by makes sense here? Would a different tag (Originally-by?)
>> make more sense?
>>
>
> Sure
Will do.
>
>> >> + * The shadow ends before the highest accessible address
>> >> + * because we don't need a shadow for the shadow. Instead:
>> >> + * c00e000000000000 << 3 + a80e 0000 0000 0000 000 = c00fc00000000000
>> >
>> > The comment has one extra 0 in a80e.., I did the math and had to use
>> > the data from the defines :)
>>
>> 3 extra 0s, even! Fixed.
>>
>> >> +void __init kasan_init(void)
>> >> +{
>> >> + /*
>> >> + * We want to do the following things:
>> >> + * 1) Map real memory into the shadow for all physical memblocks
>> >> + * This takes us from c000... to c008...
>> >> + * 2) Leave a hole over the shadow of vmalloc space. KASAN_VMALLOC
>> >> + * will manage this for us.
>> >> + * This takes us from c008... to c00a...
>> >> + * 3) Map the 'early shadow'/zero page over iomap and vmemmap space.
>> >> + * This takes us up to where we start at c00e...
>> >> + */
>> >> +
>> >
>> > assuming we have
>> > #define VMEMMAP_END R_VMEMMAP_END
>> > and ditto for hash we probably need
>> >
>> > BUILD_BUG_ON(VMEMMAP_END + KASAN_SHADOW_OFFSET != KASAN_SHADOW_END);
>>
>> Sorry, I'm not sure what this is supposed to be testing? In what
>> situation would this trigger?
>>
>
> I am bit concerned that we have hard coded (IIR) 0xa80e... in the
> config, any changes to VMEMMAP_END, KASAN_SHADOW_OFFSET/END
> should be guarded.
>
Ah that makes sense. I'll come up with some test that should catch any
unsynchronised changes to VMEMMAP_END, KASAN_SHADOW_OFFSET or
KASAN_SHADOW_END.
Kind regards,
Daniel Axtens
> Balbir Singh.
next prev parent reply other threads:[~2021-03-22 5:52 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-19 14:40 [PATCH v11 0/6] KASAN for powerpc64 radix Daniel Axtens
2021-03-19 14:40 ` [PATCH v11 1/6] kasan: allow an architecture to disable inline instrumentation Daniel Axtens
2021-03-20 1:46 ` Balbir Singh
2021-03-22 0:29 ` Daniel Axtens
2021-03-22 11:08 ` Michael Ellerman
2021-03-22 8:18 ` Marco Elver
2021-03-19 14:40 ` [PATCH v11 2/6] kasan: allow architectures to provide an outline readiness check Daniel Axtens
2021-03-22 8:17 ` Marco Elver
2021-03-19 14:40 ` [PATCH v11 3/6] kasan: define and use MAX_PTRS_PER_* for early shadow tables Daniel Axtens
2021-03-19 14:40 ` [PATCH v11 4/6] kasan: Document support on 32-bit powerpc Daniel Axtens
2021-03-19 14:40 ` [PATCH v11 5/6] powerpc/mm/kasan: rename kasan_init_32.c to init_32.c Daniel Axtens
2021-03-19 14:40 ` [PATCH v11 6/6] powerpc: Book3S 64-bit outline-only KASAN support Daniel Axtens
2021-03-20 6:02 ` Balbir Singh
2021-03-22 0:55 ` Daniel Axtens
2021-03-22 2:59 ` Balbir Singh
2021-03-22 5:52 ` Daniel Axtens [this message]
2021-03-22 15:14 ` Christophe Leroy
2021-04-21 12:29 ` Christophe Leroy
2021-03-20 1:40 ` [PATCH v11 0/6] KASAN for powerpc64 radix Balbir Singh
2021-03-22 14:32 ` Christophe Leroy
2021-03-23 1:21 ` Daniel Axtens
2021-03-23 13:27 ` Christophe Leroy
2021-03-29 23:53 ` Michael Ellerman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87lfafburj.fsf@dja-thinkpad.axtens.net \
--to=dja@axtens.net \
--cc=aneesh.kumar@linux.ibm.com \
--cc=bsingharora@gmail.com \
--cc=kasan-dev@googlegroups.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).