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Message-ID: <a40c2a60e42b5fdff46275ca42f3e7276bf11258.camel@intel.com>
Subject: Re: [RFC PATCH v6 08/11] x86: Insert endbr32/endbr64 to vDSO
From: Yu-cheng Yu <yu-cheng.yu@intel.com>
Date: Mon, 19 Nov 2018 14:43:31 -0800
In-Reply-To: <CALCETrW9ABDotyM020V147+kuizpTRJUAANn-6kUt6-h0Qn0og@mail.gmail.com>
References: <20181119214934.6174-1-yu-cheng.yu@intel.com>
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	 <CALCETrW9ABDotyM020V147+kuizpTRJUAANn-6kUt6-h0Qn0og@mail.gmail.com>
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To: Andy Lutomirski <luto@amacapital.net>
Cc: X86 ML <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, LKML <linux-kernel@vger.kernel.org>, "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>, Linux-MM <linux-mm@kvack.org>, linux-arch <linux-arch@vger.kernel.org>, Linux API <linux-api@vger.kernel.org>, Arnd Bergmann <arnd@arndb.de>, Balbir Singh <bsingharora@gmail.com>, 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>, Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>, Peter Zijlstra <peterz@infradead.org>, Randy Dunlap <rdunlap@infradead.org>, "Ravi V. Shankar" <ravi.v.shankar@intel.com>, "Shanbhogue, Vedvyas" <vedvyas.shanbhogue@intel.com>

On Mon, 2018-11-19 at 14:17 -0800, Andy Lutomirski wrote:
> On Mon, Nov 19, 2018 at 1:55 PM Yu-cheng Yu <yu-cheng.yu@intel.com> wrote:
> > 
> > From: "H.J. Lu" <hjl.tools@gmail.com>
> > 
> > When Intel indirect branch tracking is enabled, functions in vDSO which
> > may be called indirectly must have endbr32 or endbr64 as the first
> > instruction.  Compiler must support -fcf-protection=branch so that it
> > can be used to compile vDSO.
> > 
> > Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
> > ---
> >  arch/x86/entry/vdso/.gitignore        |  4 ++++
> >  arch/x86/entry/vdso/Makefile          | 12 +++++++++++-
> >  arch/x86/entry/vdso/vdso-layout.lds.S |  1 +
> >  3 files changed, 16 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/x86/entry/vdso/.gitignore b/arch/x86/entry/vdso/.gitignore
> > index aae8ffdd5880..552941fdfae0 100644
> > --- a/arch/x86/entry/vdso/.gitignore
> > +++ b/arch/x86/entry/vdso/.gitignore
> > @@ -5,3 +5,7 @@ vdso32-sysenter-syms.lds
> >  vdso32-int80-syms.lds
> >  vdso-image-*.c
> >  vdso2c
> > +vclock_gettime.S
> > +vgetcpu.S
> > +vclock_gettime.asm
> > +vgetcpu.asm
> 
> 
> What's this hunk about?

We used to allow using non-CET capable BINUTILS and the Makefile would create
these.  I will remove them from the patch.

Yu-cheng