From: Bill Wendling <morbo@google.com>
To: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Juergen Gross <jgross@suse.com>,
"Srivatsa S. Bhat (VMware)" <srivatsa@csail.mit.edu>,
Alexey Makhalov <amakhalov@vmware.com>,
VMware PV-Drivers Reviewers <pv-drivers@vmware.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
virtualization@lists.linux-foundation.org,
LKML <linux-kernel@vger.kernel.org>,
Nathan Chancellor <nathan@kernel.org>,
clang-built-linux <llvm@lists.linux.dev>,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH 2/2] x86/paravirt: add extra clobbers with ZERO_CALL_USED_REGS enabled
Date: Thu, 8 Sep 2022 22:16:04 +0100 [thread overview]
Message-ID: <CAGG=3QUcQCQXff9Hk+eHrvbAhPT16BmFGNuAGcd-N0d-G8yBKg@mail.gmail.com> (raw)
In-Reply-To: <202209071609.BE5BF18D6@keescook>
On Thu, Sep 8, 2022 at 12:10 AM Kees Cook <keescook@chromium.org> wrote:
>
> On Wed, Sep 07, 2022 at 10:50:03AM +0200, Peter Zijlstra wrote:
> > On Tue, Sep 06, 2022 at 11:00:07PM -0700, Nick Desaulniers wrote:
> > > On Sun, Sep 4, 2022 at 11:02 PM Bill Wendling <morbo@google.com> wrote:
> > > >
> > > > On Sat, Sep 3, 2022 at 12:18 AM Kees Cook <keescook@chromium.org> wrote:
> > > > >
> > > > > On Fri, Sep 02, 2022 at 09:37:50PM +0000, Bill Wendling wrote:
> > > > > > [...]
> > > > > > callq *pv_ops+536(%rip)
> > > > >
> > > > > Do you know which pv_ops function is this? I can't figure out where
> > > > > pte_offset_kernel() gets converted into a pv_ops call....
> > > > >
> > > > This one is _paravirt_ident_64, I believe. I think that the original
> > > > issue Nathan was seeing was with another seemingly innocuous function.
> > >
> > > _paravirt_ident_64 is marked noinstr, which makes me suspect that it
> > > really needs to not be touched at all by the compiler for
> > > these...special features.
> >
> > My source tree sayeth:
> >
> > u64 notrace _paravirt_ident_64(u64 x)
>
> I don't see noinstr either. But it seems a reasonable thing to do?
>
> Bill, does fixing up the noinstr macro and adding it here fix the
> problem?
>
[sorry for late response]
Let me give it a shot. I'll also test out Peter's suggestion, which
might be a better option in the long run. I suspect that we'll need to
devise similar patches for other places, but it shouldn't be hard to
find them all.
-bw
-bw
next prev parent reply other threads:[~2022-09-08 21:16 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-02 21:37 [PATCH 0/2] fix clobbers list with ZERO_CALL_USED_REGS feature Bill Wendling
2022-09-02 21:37 ` [PATCH 1/2] x86/paravirt: clean up typos and grammaros Bill Wendling
2022-09-03 4:28 ` Borislav Petkov
2022-09-04 2:13 ` Bill Wendling
2022-09-02 21:37 ` [PATCH 2/2] x86/paravirt: add extra clobbers with ZERO_CALL_USED_REGS enabled Bill Wendling
2022-09-03 7:18 ` Kees Cook
2022-09-05 6:02 ` Bill Wendling
2022-09-07 6:00 ` Nick Desaulniers
2022-09-07 8:50 ` Peter Zijlstra
2022-09-07 23:10 ` Kees Cook
2022-09-08 21:16 ` Bill Wendling [this message]
2022-09-14 14:40 ` Nathan Chancellor
2022-09-14 15:49 ` Bill Wendling
[not found] ` <20220914162149.71271-1-morbo@google.com>
2022-09-15 6:59 ` [PATCH v2 1/1] x86/paravirt: write paravirt ident function in assembly Juergen Gross
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