linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
To: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-mips@vger.kernel.org, Kees Cook <keescook@chromium.org>,
	Borislav Petkov <bp@suse.de>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	Fangrui Song <maskray@google.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/3] MIPS: Move kernel head into a standalone section
Date: Wed, 27 May 2020 15:33:56 +0200	[thread overview]
Message-ID: <20200527133356.GA16622@alpha.franken.de> (raw)
In-Reply-To: <20200527200522.23c4e86f@halation.net.flygoat.com>

On Wed, May 27, 2020 at 08:05:22PM +0800, Jiaxun Yang wrote:
> On Wed, 27 May 2020 13:53:54 +0200
> Thomas Bogendoerfer <tsbogend@alpha.franken.de> wrote:
> 
> > On Wed, May 27, 2020 at 02:34:33PM +0800, Jiaxun Yang wrote:
> > > That's what already done by Arm64 and other architectures.
> > > That would allow us put more things like PE headers safely into
> > > the header.
> > > 
> > > Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> > > ---
> > >  arch/mips/kernel/head.S        | 4 ++--
> > >  arch/mips/kernel/vmlinux.lds.S | 8 ++++++--
> > >  2 files changed, 8 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S
> > > index c7c2795837e7..8081a905a71c 100644
> > > --- a/arch/mips/kernel/head.S
> > > +++ b/arch/mips/kernel/head.S
> > > @@ -59,6 +59,8 @@
> > >  #endif
> > >  	.endm
> > >  
> > > +	__HEAD
> > > +_head:
> > >  #ifndef CONFIG_NO_EXCEPT_FILL
> > >  	/*
> > >  	 * Reserved space for exception handlers.  
> > 
> > I'm adding the missing piece, why this change ist broken:
> > 
> >          * Necessary for machines which link their kernels at KSEG0.
> > 
> > by putting something in front of that will probably break platforms
> > making use of "feature". If we can make sure, we don't need it
> > anymore, we should first remove this and then add __HEAD part.
> 
> __HEAD is just marking the section of code.
> It will not add anything to the binary.

oops, should have looked it up first. You mentioned PE headers and
I thought it will be added this way.

> Btw: I just noticed this patch may break relocatable kernel. I'll delay
> it for next merge window.

ok.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]

  reply	other threads:[~2020-05-27 13:34 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-27  6:34 [PATCH v2 0/3] Buggy bootloader workaround v2 Jiaxun Yang
2020-05-27  6:34 ` [PATCH v2 1/3] MIPS: head.S: Always jump to kernel_entry at head of text Jiaxun Yang
2020-05-27 11:41   ` Thomas Bogendoerfer
2020-05-27  6:34 ` [PATCH v2 2/3] MIPS: Move kernel head into a standalone section Jiaxun Yang
2020-05-27 11:53   ` Thomas Bogendoerfer
2020-05-27 12:05     ` Jiaxun Yang
2020-05-27 13:33       ` Thomas Bogendoerfer [this message]
2020-05-27  6:34 ` [PATCH v2 3/3] MIPS: Loongson64: select NO_EXCEPT_FILL Jiaxun Yang
2020-05-27 11:47   ` Thomas Bogendoerfer

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=20200527133356.GA16622@alpha.franken.de \
    --to=tsbogend@alpha.franken.de \
    --cc=bp@suse.de \
    --cc=heiko.carstens@de.ibm.com \
    --cc=jiaxun.yang@flygoat.com \
    --cc=keescook@chromium.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mips@vger.kernel.org \
    --cc=maskray@google.com \
    /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).