Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Sender: Arvind Sankar <niveditas98@gmail.com>
From:   Arvind Sankar <nivedita@alum.mit.edu>
Date:   Mon, 21 Dec 2020 16:23:00 -0500
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Arvind Sankar <nivedita@alum.mit.edu>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86/cmdline: Disable jump tables for cmdline.c
Message-ID: <X+ESNP6HdYQpd7g3@rani.riverdale.lan>
References: <20200903023056.3914690-1-nivedita@alum.mit.edu>
 <CAKwvOdm8qUpueOdO7e-rQotO5UynrgU2TZ9DEe=O4f9eU5EY0g@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <CAKwvOdm8qUpueOdO7e-rQotO5UynrgU2TZ9DEe=O4f9eU5EY0g@mail.gmail.com>
Precedence: bulk

On Mon, Dec 21, 2020 at 11:14:39AM -0800, Nick Desaulniers wrote:
> On Wed, Sep 2, 2020 at 7:31 PM Arvind Sankar <nivedita@alum.mit.edu> wrote:
> >
> > When CONFIG_RETPOLINE is disabled, Clang uses a jump table for the
> > switch statement in cmdline_find_option (jump tables are disabled when
> > CONFIG_RETPOLINE is enabled). This function is called very early in boot
> > from sme_enable() if CONFIG_AMD_MEM_ENCRYPT is enabled. At this time,
> 
> Hi Arvind, sorry I missed this when you first sent it.  I'm going
> through and mass deleting my inbox (email bankruptcy) but noticed
> this.  I couldn't reproduce jump tables in cmdline_find_option with
> CONFIG_RETPOLINE disabled but CONFIG_AMD_MEM_ENCRYPT on today's
> linux-next. Can you please confirm that this is still an issue? I will
> reread the disassembly, but it looks like a bunch of cmp/test+jumps.
> 

The patch got merged and is in v5.10 -- are you testing with it reverted
or just plain linux-next?