Received-SPF: pass (google.com: domain of linux-kernel+bounces-93973-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Precedence: bulk
MIME-Version: 1.0
References: <20240306085622.87248-1-cuiyunhui@bytedance.com>
 <26f3e99c-8f57-4779-a679-2085e469d9cd@siemens.com> <CAEEQ3wnDKdhCH4yz+MY+Xks21jLnuFiyx-xxa7CFczokG2shvQ@mail.gmail.com>
 <CAMj1kXFxzFRQz0BUVw27xdOj+xAVtX9jPjwaLHsEOYDUSqXMOw@mail.gmail.com>
In-Reply-To: <CAMj1kXFxzFRQz0BUVw27xdOj+xAVtX9jPjwaLHsEOYDUSqXMOw@mail.gmail.com>
From: yunhui cui <cuiyunhui@bytedance.com>
Date: Wed, 6 Mar 2024 21:26:50 +0800
Message-ID: <CAEEQ3wnvTN5nGWAibjKKdMe4P3j3wPgghKn2HbOF1Xg56G=0kQ@mail.gmail.com>
Subject: Re: [External] Re: [PATCH 1/3] Revert "riscv/efistub: Ensure
 GP-relative addressing is not used"
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Jan Kiszka <jan.kiszka@siemens.com>, paul.walmsley@sifive.com, palmer@dabbelt.com, 
	aou@eecs.berkeley.edu, xuzhipeng.1973@bytedance.com, alexghiti@rivosinc.com, 
	samitolvanen@google.com, bp@alien8.de, xiao.w.wang@intel.com, 
	kirill.shutemov@linux.intel.com, nathan@kernel.org, 
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, 
	linux-efi@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

Hi Ard,

On Wed, Mar 6, 2024 at 9:11=E2=80=AFPM Ard Biesheuvel <ardb@kernel.org> wro=
te:
>
> On Wed, 6 Mar 2024 at 14:08, yunhui cui <cuiyunhui@bytedance.com> wrote:
> >
> > Hi Jan,
> >
> > On Wed, Mar 6, 2024 at 8:52=E2=80=AFPM Jan Kiszka <jan.kiszka@siemens.c=
om> wrote:
> > >
> > > On 06.03.24 09:56, Yunhui Cui wrote:
> > > > This reverts commit afb2a4fb84555ef9e61061f6ea63ed7087b295d5.
> > > >
> > >
> > > This comes without a reason - which is likely something around "will =
fix
> > > this properly later". But then you regress first and only fix
> > > afterwards. Can't that be done the other way around?
> >
> > Sorry, I don't quite understand what you mean. Can you help explain it
> > more clearly? Do you mean "delete mno-relax instead of revert
> > directly?"
> >
>
> You should order your patches in a way that does not create
> intermediate states (between 1-2 or between 2-3) where the original
> problem is being recreated.
>
> So in this case, you should
> a) fix the issue
> b) revert the existing patches in *opposite* order
Simply, I plan to remove "-mno-relax" and
"\|R_RISCV_$(BITS)\|R_RISCV_RELAX" in the third patch (fix patch).


> However, I don't think the EFI stub can use GP - please refer to my other=
 reply.
The problem we encountered is that gcc 13 will optimize efistub using gp.

Thanks,
Yunhui