From: Nick Desaulniers <ndesaulniers@google.com>
To: Arvind Sankar <nivedita@alum.mit.edu>
Cc: "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
Date: Mon, 21 Dec 2020 13:40:44 -0800 [thread overview]
Message-ID: <CAKwvOd=y7J8ehoEaFBLwS0UdC_mPbACenfRL9ssSy+UPUFGwTQ@mail.gmail.com> (raw)
In-Reply-To: <X+ESNP6HdYQpd7g3@rani.riverdale.lan>
On Mon, Dec 21, 2020 at 1:23 PM Arvind Sankar <nivedita@alum.mit.edu> wrote:
>
> 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?
Oh, sorry, I missed any email that it was merged (and didn't look in
git log). Just linux-next, so no wonder I didn't see any jump tables.
:^P
--
Thanks,
~Nick Desaulniers
prev parent reply other threads:[~2020-12-21 21:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-03 2:30 [PATCH] x86/cmdline: Disable jump tables for cmdline.c Arvind Sankar
2020-09-03 9:00 ` [tip: x86/urgent] " tip-bot2 for Arvind Sankar
2020-12-21 19:14 ` [PATCH] " Nick Desaulniers
2020-12-21 21:23 ` Arvind Sankar
2020-12-21 21:40 ` Nick Desaulniers [this message]
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='CAKwvOd=y7J8ehoEaFBLwS0UdC_mPbACenfRL9ssSy+UPUFGwTQ@mail.gmail.com' \
--to=ndesaulniers@google.com \
--cc=bp@alien8.de \
--cc=clang-built-linux@googlegroups.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=nivedita@alum.mit.edu \
--cc=tglx@linutronix.de \
--cc=thomas.lendacky@amd.com \
--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).