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Re: [PATCHv2 2/6] x86/vdso: introduce do_map_vdso() and vdso_type enum

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On Wed, Jun 29, 2016 at 3:57 AM, Dmitry Safonov <dsafonov@virtuozzo.com> wrote:
> Make in-kernel API to map vDSO blobs on x86.

I think the addr calculation was already confusing and is now even
worse.  How about simplifying it?  Get rid of calculate_addr entirely
and push the vdso_addr calls into arch_setup_additional_pages, etc.
Then just use addr directly in the map_vdso code.

> +int do_map_vdso(vdso_type type, unsigned long addr, bool randomize_addr)
>  {
> -       if (vdso32_enabled != 1)  /* Other values all mean "disabled" */
> -               return 0;
> -
> -       return map_vdso(&vdso_image_32, false);
> -}
> +       switch (type) {
> +#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
> +       case VDSO_32:
> +               if (vdso32_enabled != 1)  /* Other values all mean "disabled" */
> +                       return 0;
> +               /* vDSO aslr turned off for i386 vDSO */
> +               return map_vdso(&vdso_image_32, addr, false);
> +#endif
> +#ifdef CONFIG_X86_64
> +       case VDSO_64:
> +               if (!vdso64_enabled)
> +                       return 0;
> +               return map_vdso(&vdso_image_64, addr, randomize_addr);
> +#endif
> +#ifdef CONFIG_X86_X32_ABI
> +       case VDSO_X32:
> +               if (!vdso64_enabled)
> +                       return 0;
> +               return map_vdso(&vdso_image_x32, addr, randomize_addr);
>  #endif
> +       default:
> +               return -EINVAL;
> +       }
> +}

Why is this better than just passing the vdso_image pointer in?

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Re: [PATCHv2 2/6] x86/vdso: introduce do_map_vdso() and vdso_type enum Andy Lutomirski <luto@amacapital.net> - 2016-07-06 16:30 +0200

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