Re: [PATCH V5 17/21] riscv: compat: vdso: Add setup additional pages implementation

[Guo Ren]

On Wed, Feb 23, 2022 at 8:19 PM Rolf Eike Beer <eb@xxxxxxxxx> wrote:
>
> > @@ -66,35 +68,35 @@ static int vdso_mremap(const struct vm_special_mapping
> > *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
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>
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-- 
Best Regards
 Guo Ren

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