Re: [PATCH][v10] PM / hibernate: Verify the consistent of e820 memory map by md5 digest

[Rafael J. Wysocki]

On Fri, Sep 9, 2016 at 2:21 PM, Chen Yu <yu.c.chen@xxxxxxxxx> wrote:
> On some platforms, there is occasional panic triggered when trying to
> resume from hibernation, a typical panic looks like:

[cut]

> @@ -211,10 +292,15 @@ int arch_hibernation_header_save(void *addr, unsigned int max_size)
>   */
>  int arch_hibernation_header_restore(void *addr)
>  {
> +       bool e820_mismatch = false;

The extra local variable can be avoided if you structure the code
slightly differently.

>         struct restore_data_record *rdr = addr;
>
>         restore_jump_address = rdr->jump_address;
>         jump_address_phys = rdr->jump_address_phys;
>         restore_cr3 = rdr->cr3;
> -       return (rdr->magic == RESTORE_MAGIC) ? 0 : -EINVAL;
> +
> +       e820_mismatch = hibernation_e820_mismatch(rdr->e820_digest);

Also calling hibernation_e820_mismatch() before checking rdr->magic
may not be useful at all.

> +
> +       return (rdr->magic == RESTORE_MAGIC) ?
> +               (e820_mismatch ? -ENODEV : 0) : -EINVAL;

So what about:

if (rdr->magic != RESTORE_MAGIC)
        return -EINVAL;

if (hibernation_e820_mismatch(rdr->e820_digest))
        return -ENODEV;

return 0;


>  }
> --

Thanks,
Rafael