From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-mm@kvack.org, linux-arch@vger.kernel.org,
linux-api@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Andy Lutomirski <luto@amacapital.net>,
Balbir Singh <bsingharora@gmail.com>,
Borislav Petkov <bp@alien8.de>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Eugene Syromiatnikov <esyr@redhat.com>,
Florian Weimer <fweimer@redhat.com>,
"H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
Jonathan Corbet <corbet@lwn.net>,
Kees Cook <keescook@chromium.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Nadav Amit <nadav.amit@gmail.com>
Subject: Re: [PATCH v8 11/27] x86/mm: Introduce _PAGE_DIRTY_SW
Date: Wed, 28 Aug 2019 07:57:41 -0700 [thread overview]
Message-ID: <29e6afa9cd7a7b0069ec6b999a2830cbbbe50a56.camel@intel.com> (raw)
In-Reply-To: <20190828070308.GJ2332@hirez.programming.kicks-ass.net>
On Wed, 2019-08-28 at 09:03 +0200, Peter Zijlstra wrote:
> On Tue, Aug 27, 2019 at 03:37:12PM -0700, Yu-cheng Yu wrote:
> > On Fri, 2019-08-23 at 16:02 +0200, Peter Zijlstra wrote:
> > > On Tue, Aug 13, 2019 at 01:52:09PM -0700, Yu-cheng Yu wrote:
> > >
> > > > +static inline pte_t pte_move_flags(pte_t pte, pteval_t from, pteval_t
> > > > to)
> > > > +{
> > > > + if (pte_flags(pte) & from)
> > > > + pte = pte_set_flags(pte_clear_flags(pte, from), to);
> > > > + return pte;
> > > > +}
> > >
> > > Aside of the whole conditional thing (I agree it would be better to have
> > > this unconditionally); the function doesn't really do as advertised.
> > >
> > > That is, if @from is clear, it doesn't endeavour to make sure @to is
> > > also clear.
> > >
> > > Now it might be sufficient, but in that case it really needs a comment
> > > and or different name.
> > >
> > > An implementation that actually moves the bit is something like:
> > >
> > > pteval_t a,b;
> > >
> > > a = native_pte_value(pte);
> > > b = (a >> from_bit) & 1;
> > > a &= ~((1ULL << from_bit) | (1ULL << to_bit));
> > > a |= b << to_bit;
> > > return make_native_pte(a);
> >
> > There can be places calling pte_wrprotect() on a PTE that is already RO +
> > DIRTY_SW. Then in pte_move_flags(pte, _PAGE_DIRTY_HW, _PAGE_DIRTY_SW) we do
> > not
> > want to clear _PAGE_DIRTY_SW. But, I will look into this and make it more
> > obvious.
>
> Well, then the name 'move' is just wrong, because that is not the
> semantics you're looking for.
>
> So the thing is; if you provide a generic function that 'munges' two
> bits, then it's name had better be accurate. But AFAICT you only ever
> used this for the DIRTY bits, so it might be better to have a function
> specifically for that and with a comment that spells out the exact
> semantics and reasons for them.
Yes, I will work on that.
Yu-cheng
next prev parent reply other threads:[~2019-08-28 14:57 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-13 20:51 [PATCH v8 00/27] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2019-08-13 20:51 ` [PATCH v8 01/27] Documentation/x86: Add CET description Yu-cheng Yu
2019-08-14 8:07 ` Florian Weimer
2019-08-14 15:57 ` Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 02/27] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2019-08-21 10:20 ` Borislav Petkov
2019-08-21 14:46 ` Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 03/27] x86/fpu/xstate: Change names to separate XSAVES system and user states Yu-cheng Yu
2019-08-21 14:45 ` Borislav Petkov
2019-08-13 20:52 ` [PATCH v8 04/27] x86/fpu/xstate: Introduce XSAVES system states Yu-cheng Yu
2019-08-16 19:56 ` Thomas Gleixner
2019-08-16 19:59 ` Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 05/27] x86/fpu/xstate: Introduce CET MSR " Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 06/27] x86/cet: Add control protection exception handler Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 07/27] x86/cet/shstk: Add Kconfig option for user-mode shadow stack Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 08/27] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 09/27] mm/mmap: Prevent Shadow Stack VMA merges Yu-cheng Yu
2019-08-13 22:34 ` Dave Hansen
2019-08-14 16:20 ` Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 10/27] x86/mm: Change _PAGE_DIRTY to _PAGE_DIRTY_HW Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 11/27] x86/mm: Introduce _PAGE_DIRTY_SW Yu-cheng Yu
2019-08-13 23:02 ` Dave Hansen
2019-08-13 23:49 ` Andy Lutomirski
2019-08-14 16:42 ` Yu-cheng Yu
2019-08-14 16:58 ` Dave Hansen
2019-08-23 14:02 ` Peter Zijlstra
2019-08-27 22:37 ` Yu-cheng Yu
2019-08-28 7:03 ` Peter Zijlstra
2019-08-28 14:57 ` Yu-cheng Yu [this message]
2019-08-13 20:52 ` [PATCH v8 12/27] drm/i915/gvt: Update _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 13/27] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 14/27] x86/mm: Shadow stack page fault error checking Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 15/27] mm: Handle shadow stack page fault Yu-cheng Yu
2019-08-13 22:55 ` Andy Lutomirski
2019-08-14 16:27 ` Yu-cheng Yu
2019-08-14 16:48 ` Dave Hansen
2019-08-14 17:00 ` Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 16/27] mm: Handle THP/HugeTLB " Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 17/27] mm: Update can_follow_write_pte/pmd for shadow stack Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 18/27] mm: Introduce do_mmap_locked() Yu-cheng Yu
2019-08-20 1:02 ` Sean Christopherson
2019-08-20 16:08 ` Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 19/27] x86/cet/shstk: User-mode shadow stack support Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 20/27] x86/cet/shstk: Introduce WRUSS instruction Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 21/27] x86/cet/shstk: Handle signals for shadow stack Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 22/27] binfmt_elf: Extract .note.gnu.property from an ELF file Yu-cheng Yu
2019-08-16 13:55 ` Dave Martin
2019-08-20 10:02 ` Dave Martin
2019-08-13 20:52 ` [PATCH v8 23/27] x86/cet/shstk: ELF header parsing of Shadow Stack Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 24/27] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 25/27] mm/mmap: Add Shadow stack pages to memory accounting Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 26/27] x86/cet/shstk: Add arch_prctl functions for Shadow Stack Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 27/27] x86/cet/shstk: Add Shadow Stack instructions to opcode map Yu-cheng Yu
2019-11-08 13:27 ` Adrian Hunter
2019-11-08 18:09 ` Yu-cheng Yu
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=29e6afa9cd7a7b0069ec6b999a2830cbbbe50a56.camel@intel.com \
--to=yu-cheng.yu@intel.com \
--cc=arnd@arndb.de \
--cc=bp@alien8.de \
--cc=bsingharora@gmail.com \
--cc=corbet@lwn.net \
--cc=dave.hansen@linux.intel.com \
--cc=esyr@redhat.com \
--cc=fweimer@redhat.com \
--cc=gorcunov@gmail.com \
--cc=hjl.tools@gmail.com \
--cc=hpa@zytor.com \
--cc=jannh@google.com \
--cc=keescook@chromium.org \
--cc=linux-api@vger.kernel.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=luto@amacapital.net \
--cc=mike.kravetz@oracle.com \
--cc=mingo@redhat.com \
--cc=nadav.amit@gmail.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=x86@kernel.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).