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From:   Guo Ren <guoren@kernel.org>
Date:   Wed, 23 Feb 2022 20:42:26 +0800
Message-ID: <CAJF2gTRcfvd6Sin=3Dv91WZO6DxLsUsB=ap+F1WehKb6=w5fkA@mail.gmail.com>
Subject: Re: [PATCH V5 17/21] riscv: compat: vdso: Add setup additional pages implementation
To:     Rolf Eike Beer <eb@emlix.com>
Cc:     Palmer Dabbelt <palmer@dabbelt.com>, Arnd Bergmann <arnd@arndb.de>,
        Anup Patel <anup@brainfault.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        liush <liush@allwinnertech.com>, Wei Fu <wefu@redhat.com>,
        Drew Fustini <drew@beagleboard.org>,
        Wang Junqiang <wangjunqiang@iscas.ac.cn>,
        Christoph Hellwig <hch@lst.de>,
        linux-arch <linux-arch@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        linux-csky@vger.kernel.org,
        linux-s390 <linux-s390@vger.kernel.org>,
        sparclinux <sparclinux@vger.kernel.org>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        Parisc List <linux-parisc@vger.kernel.org>,
        "open list:BROADCOM NVRAM DRIVER" <linux-mips@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        Guo Ren <guoren@linux.alibaba.com>
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On Wed, Feb 23, 2022 at 8:19 PM Rolf Eike Beer <eb@emlix.com> wrote:
>
> > @@ -66,35 +68,35 @@ static int vdso_mremap(const struct vm_special_mapp=
ing
> > *sm, return 0;
> >  }
> >
> > -static int __init __vdso_init(void)
> > +static int __init __vdso_init(struct __vdso_info *vdso_info)
> >  {
> >       unsigned int i;
> >       struct page **vdso_pagelist;
> >       unsigned long pfn;
> >
> > -     if (memcmp(vdso_info.vdso_code_start, "\177ELF", 4)) {
> > +     if (memcmp(vdso_info->vdso_code_start, "\177ELF", 4)) {
> >               pr_err("vDSO is not a valid ELF object!\n");
> >               return -EINVAL;
> >       }
> >
>
> Does anyone actually guarantee that this is at least this 4 bytes long?

You can ref:
arch/arm64/kernel/vdso.c
arch/arm/kernel/vdso.c
arch/nds32/kernel/vdso.c

and in arch/powerpc/boot/elf.h:
arch/powerpc/kernel/fadump.c:   memcpy(elf->e_ident, ELFMAG, SELFMAG);
arch/powerpc/boot/elf.h:#define ELFMAG0         0x7f    /* EI_MAG */
arch/powerpc/boot/elf.h:#define ELFMAG1         'E'
arch/powerpc/boot/elf.h:#define ELFMAG2         'L'
arch/powerpc/boot/elf.h:#define ELFMAG3         'F'
arch/powerpc/boot/elf.h:#define ELFMAG          "\177ELF"
arch/powerpc/boot/elf.h:#define SELFMAG         4


>
> Eike
> --
> Rolf Eike Beer, emlix GmbH, https://www.emlix.com
> Fon +49 551 30664-0, Fax +49 551 30664-11
> Gothaer Platz 3, 37083 G=C3=B6ttingen, Germany
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> Gesch=C3=A4ftsf=C3=BChrung: Heike Jordan, Dr. Uwe Kracke =E2=80=93 Ust-Id=
Nr.: DE 205 198 055
>
> emlix - smart embedded open source


--=20
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/