From: Peter Zijlstra <peterz@infradead.org>
To: Igor Stoppa <igor.stoppa@gmail.com>
Cc: Igor Stoppa <igor.stoppa@huawei.com>,
Andy Lutomirski <luto@amacapital.net>,
Nadav Amit <nadav.amit@gmail.com>,
Matthew Wilcox <willy@infradead.org>,
Kees Cook <keescook@chromium.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Mimi Zohar <zohar@linux.vnet.ibm.com>,
Thiago Jung Bauermann <bauerman@linux.ibm.com>,
Ahmed Soliman <ahmedsoliman@mena.vt.edu>,
linux-integrity@vger.kernel.org,
kernel-hardening@lists.openwall.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v5 03/12] __wr_after_init: Core and default arch
Date: Fri, 15 Feb 2019 09:57:36 +0100 [thread overview]
Message-ID: <20190215085736.GO32494@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <6e9ec71c-ee75-9b1e-9ff8-a3210030e85d@gmail.com>
On Fri, Feb 15, 2019 at 01:10:33AM +0200, Igor Stoppa wrote:
>
>
> On 14/02/2019 13:28, Peter Zijlstra wrote:
> > On Thu, Feb 14, 2019 at 12:41:32AM +0200, Igor Stoppa wrote:
>
> [...]
>
> > > +#define wr_rcu_assign_pointer(p, v) ({ \
> > > + smp_mb(); \
> > > + wr_assign(p, v); \
> > > + p; \
> > > +})
> >
> > This requires that wr_memcpy() (through wr_assign) is single-copy-atomic
> > for native types. There is not a comment in sight that states this.
>
> Right, I kinda expected native-aligned <-> atomic, but it's not necessarily
> true. It should be confirmed when enabling write rare on a new architecture.
> I'll add the comment.
>
> > Also, is this true of x86/arm64 memcpy ?
>
>
> For x86_64:
> https://elixir.bootlin.com/linux/v5.0-rc6/source/arch/x86/include/asm/uaccess.h#L462
> the mov"itype" part should deal with atomic copy of native, aligned types.
>
>
> For arm64:
> https://elixir.bootlin.com/linux/v5.0-rc6/source/arch/arm64/lib/copy_template.S#L110
> .Ltiny15 deals with copying less than 16 bytes, which includes pointers.
> When the data is aligned, the copy of a pointer should be atomic.
>
Where are the comments and Changelog notes ? How is an arch maintainer
to be aware of this requirement when adding support for his/her arch?
next prev parent reply other threads:[~2019-02-15 8:57 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-13 22:41 [RFC PATCH v5 00/12] hardening: statically allocated protected memory Igor Stoppa
2019-02-13 22:41 ` [RFC PATCH v5 02/12] __wr_after_init: linker section and attribute Igor Stoppa
2019-02-13 22:41 ` [RFC PATCH v5 03/12] __wr_after_init: Core and default arch Igor Stoppa
2019-02-14 11:28 ` Peter Zijlstra
2019-02-14 23:10 ` Igor Stoppa
2019-02-15 8:57 ` Peter Zijlstra [this message]
2019-02-16 15:15 ` Igor Stoppa
2019-02-13 22:41 ` [RFC PATCH v5 04/12] __wr_after_init: x86_64: randomize mapping offset Igor Stoppa
2019-02-13 22:41 ` [RFC PATCH v5 05/12] __wr_after_init: x86_64: enable Igor Stoppa
2019-02-13 22:41 ` [RFC PATCH v5 06/12] __wr_after_init: arm64: enable Igor Stoppa
2019-02-13 22:41 ` [RFC PATCH v5 07/12] __wr_after_init: Documentation: self-protection Igor Stoppa
2019-02-13 22:41 ` [RFC PATCH v5 08/12] __wr_after_init: lkdtm test Igor Stoppa
2019-02-13 22:41 ` [RFC PATCH v5 09/12] __wr_after_init: rodata_test: refactor tests Igor Stoppa
2019-02-13 22:41 ` [RFC PATCH v5 10/12] __wr_after_init: rodata_test: test __wr_after_init Igor Stoppa
2019-02-13 22:41 ` [RFC PATCH v5 11/12] __wr_after_init: test write rare functionality Igor Stoppa
2019-02-13 22:41 ` [RFC PATCH v5 12/12] IMA: turn ima_policy_flags into __wr_after_init Igor Stoppa
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=20190215085736.GO32494@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=ahmedsoliman@mena.vt.edu \
--cc=bauerman@linux.ibm.com \
--cc=dave.hansen@linux.intel.com \
--cc=igor.stoppa@gmail.com \
--cc=igor.stoppa@huawei.com \
--cc=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=luto@amacapital.net \
--cc=nadav.amit@gmail.com \
--cc=willy@infradead.org \
--cc=zohar@linux.vnet.ibm.com \
/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).