Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <39d3b56e3265e70d26e1d08698b461d81c3e1c1d.camel@xry111.site>
Subject: Re: [PATCH 1/5] LoongArch: Add section of GOT for kernel module
From:   Xi Ruoyao <xry111@xry111.site>
To:     Youling Tang <tangyouling@loongson.cn>, loongarch@lists.linux.dev
Cc:     linux-kernel@vger.kernel.org, WANG Xuerui <kernel@xen0n.name>,
        Huacai Chen <chenhuacai@kernel.org>
Date:   Thu, 28 Jul 2022 18:53:24 +0800
In-Reply-To: <fac4319d-26ee-1702-518c-2d6fbb1a0d57@loongson.cn>
References: <385f63bcbee8e37c42f479ce9cdc7e7d731d419b.camel@xry111.site>
         <3f43d51d530344f73a0a7087407799ff9dff3ba8.camel@xry111.site>
         <849f514e-f78a-72a2-b94e-6974074b75eb@loongson.cn>
         <00914cf65b64e06f370213fdc079111aa2a27145.camel@xry111.site>
         <fac4319d-26ee-1702-518c-2d6fbb1a0d57@loongson.cn>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
User-Agent: Evolution 3.44.3 
MIME-Version: 1.0
Precedence: bulk

On Thu, 2022-07-28 at 17:21 +0800, Youling Tang wrote:
>=20
>=20
> On 07/28/2022 05:02 PM, Xi Ruoyao wrote:
> > On Thu, 2022-07-28 at 16:29 +0800, Youling Tang wrote:
> > > On 07/28/2022 12:26 AM, Xi Ruoyao wrote:
> > > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0mod->arch.got.shdr->sh_t=
ype =3D SHT_NOBITS;
> > > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0mod->arch.got.shdr->sh_f=
lags =3D SHF_ALLOC;
> > > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0mod->arch.got.shdr->sh_a=
ddralign =3D L1_CACHE_BYTES;
> > > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0mod->arch.got.shdr->sh_s=
ize =3D (num_plts + 1) *
> > > > sizeof(struct plt_entry);
> > > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0mod->arch.got.num_entrie=
s =3D 0;
> > > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0mod->arch.got.max_entrie=
s =3D num_plts;
> > > =C2=A0Hi, Ruoyao
> > >=20
> > > =C2=A0 We should use num_gots instead of num_plts when creating .got
> > > section.
> >=20
> > Yes, it's a stupid error and I'll fix it in V2.
> >=20
> > But why didn't this cause a malfunction on my system? :(.
>=20
> Maybe num_plts is greater than num_gots, and the size of plt_entry is=20
> equivalent to the size of four got_entry, so that when the module is=20
> loaded, it just allocates a larger space without causing the module to
> fail to load.

I'll write a module to load address of 10 kernel symbols with only one
printk call to test before sending V2 :).

--=20
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University