From: Igor Stoppa <igor.stoppa@gmail.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>,
Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Mimi Zohar <zohar@linux.vnet.ibm.com>,
Igor Stoppa <igor.stoppa@huawei.com>,
Nadav Amit <nadav.amit@gmail.com>,
Kees Cook <keescook@chromium.org>,
linux-integrity <linux-integrity@vger.kernel.org>,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 04/12] __wr_after_init: x86_64: __wr_op
Date: Fri, 21 Dec 2018 19:42:26 +0200 [thread overview]
Message-ID: <187b5db9-63e4-05c2-ddb4-004969edb4d2@gmail.com> (raw)
In-Reply-To: <CALCETrU8GZbF2oWYeKUVKBURuh1zeMqcHM5RMTchiDsdrSSVPA@mail.gmail.com>
On 21/12/2018 19:23, Andy Lutomirski wrote:
> On Thu, Dec 20, 2018 at 11:19 AM Igor Stoppa <igor.stoppa@gmail.com> wrote:
>>
>>
>>
>> On 20/12/2018 20:49, Matthew Wilcox wrote:
>>
>>> I think you're causing yourself more headaches by implementing this "op"
>>> function.
>>
>> I probably misinterpreted the initial criticism on my first patchset,
>> about duplication. Somehow, I'm still thinking to the endgame of having
>> higher-level functions, like list management.
>>
>>> Here's some generic code:
>>
>> thank you, I have one question, below
>>
>>> void *wr_memcpy(void *dst, void *src, unsigned int len)
>>> {
>>> wr_state_t wr_state;
>>> void *wr_poking_addr = __wr_addr(dst);
>>>
>>> local_irq_disable();
>>> wr_enable(&wr_state);
>>> __wr_memcpy(wr_poking_addr, src, len);
>>
>> Is __wraddr() invoked inside wm_memcpy() instead of being invoked
>> privately within __wr_memcpy() because the code is generic, or is there
>> some other reason?
>>
>>> wr_disable(&wr_state);
>>> local_irq_enable();
>>>
>>> return dst;
>>> }
>>>
>>> Now, x86 can define appropriate macros and functions to use the temporary_mm
>>> functionality, and other architectures can do what makes sense to them.
> I suspect that most architectures will want to do this exactly like
> x86, though, but sure, it could be restructured like this.
In spirit, I think yes, but already I couldn't find a clean ways to do
multi-arch wr_enable(&wr_state), so I made that too become arch_dependent.
Maybe after implementing write rare for a few archs, it becomes more
clear (to me, any advice is welcome) which parts can be considered common.
> On x86, I *think* that __wr_memcpy() will want to special-case len ==
> 1, 2, 4, and (on 64-bit) 8 byte writes to keep them atomic. i'm
> guessing this is the same on most or all architectures.
I switched to xxx_user() approach, as you suggested.
For x86_64 I'm using copy_user() and i added a memset_user(), based on
copy_user().
It's already assembly code optimized for dealing with multiples of
8-byte words or subsets. You can see this in the first patch of the
patchset, even this one.
I'll send out the v3 patchset in a short while.
--
igor
next prev parent reply other threads:[~2018-12-21 17:42 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-19 21:33 [RFC v2 PATCH 0/12] hardening: statically allocated protected memory Igor Stoppa
2018-12-19 21:33 ` [PATCH 01/12] x86_64: memset_user() Igor Stoppa
2018-12-19 21:33 ` [PATCH 02/12] __wr_after_init: linker section and label Igor Stoppa
2018-12-19 21:33 ` [PATCH 03/12] __wr_after_init: generic header Igor Stoppa
2018-12-21 19:38 ` Nadav Amit
2018-12-21 19:45 ` Matthew Wilcox
2018-12-23 2:28 ` Igor Stoppa
2018-12-19 21:33 ` [PATCH 04/12] __wr_after_init: x86_64: __wr_op Igor Stoppa
2018-12-20 16:53 ` Igor Stoppa
2018-12-20 17:20 ` Thiago Jung Bauermann
2018-12-20 17:46 ` Igor Stoppa
2018-12-20 18:49 ` Matthew Wilcox
2018-12-20 19:19 ` Igor Stoppa
2018-12-20 19:27 ` Matthew Wilcox
2018-12-21 17:23 ` Andy Lutomirski
2018-12-21 17:42 ` Igor Stoppa [this message]
2018-12-19 21:33 ` [PATCH 05/12] __wr_after_init: x86_64: debug writes Igor Stoppa
2018-12-19 21:33 ` [PATCH 06/12] __wr_after_init: Documentation: self-protection Igor Stoppa
2018-12-19 21:33 ` [PATCH 07/12] __wr_after_init: lkdtm test Igor Stoppa
2018-12-19 21:33 ` [PATCH 08/12] rodata_test: refactor tests Igor Stoppa
2018-12-19 21:33 ` [PATCH 09/12] rodata_test: add verification for __wr_after_init Igor Stoppa
2018-12-19 21:33 ` [PATCH 10/12] __wr_after_init: test write rare functionality Igor Stoppa
2018-12-19 21:33 ` [PATCH 11/12] IMA: turn ima_policy_flags into __wr_after_init Igor Stoppa
2018-12-20 17:30 ` Thiago Jung Bauermann
2018-12-20 17:49 ` Igor Stoppa
2018-12-19 21:33 ` [PATCH 12/12] x86_64: __clear_user as case of __memset_user Igor Stoppa
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