Re: [PATCH v3] mbi: use per segment a separate relocator chunk

[Daniel Kiper]

On Tue, Jun 12, 2018 at 08:19:35PM +0200, Alexander Boettcher wrote:
> Instead of setting up a all comprising relocator chunk for all segments,
> use per segment a separate relocator chunk.
>
> If the ELF is non-relocatable, a single relocator chunk will comprise memory

s/If/Currently, if/

> (between the segments) which gets overridden by the relst() invocation of the
> movers code in grub_relocator16/32/64_boot().
>

Please drop this empty line and start next sentence immediately behind previous 
one.

> The overridden memory may contain reserved ranges like VGA memory or ACPI
> tables, which leads to strange boot behaviour.

s/leads/may lead to crashes or at least/

> Signed-off-by: Alexander Boettcher <address@hidden>
> ---
>  grub-core/loader/multiboot_elfxx.c | 58 
> +++++++++++++++++++++++---------------
>  1 file changed, 36 insertions(+), 22 deletions(-)
>
> diff --git a/grub-core/loader/multiboot_elfxx.c 
> b/grub-core/loader/multiboot_elfxx.c
> index 67daf59..f493b0a 100644
> --- a/grub-core/loader/multiboot_elfxx.c
> +++ b/grub-core/loader/multiboot_elfxx.c
> @@ -57,9 +57,9 @@ CONCAT(grub_multiboot_load_elf, XX) (mbi_load_data_t *mld)
>    char *phdr_base;
>    grub_err_t err;
>    grub_relocator_chunk_t ch;
> -  grub_uint32_t load_offset, load_size;
> +  grub_uint32_t load_offset = 0, load_size;
>    int i;
> -  void *source;
> +  void *source = NULL;
>
>    if (ehdr->e_ident[EI_MAG0] != ELFMAG0
>        || ehdr->e_ident[EI_MAG1] != ELFMAG1
> @@ -97,10 +97,13 @@ CONCAT(grub_multiboot_load_elf, XX) (mbi_load_data_t *mld)
>      return grub_error (GRUB_ERR_BAD_OS, "segment crosses 4 GiB border");
>  #endif
>
> -  load_size = highest_load - mld->link_base_addr;
> -
>    if (mld->relocatable)
>      {
> +      load_size = highest_load - mld->link_base_addr;
> +
> +      grub_dprintf ("multiboot_loader", "align=0x%lx, preference=0x%x, 
> load_size=0x%x avoid_efi_boot_services=%d\n",
> +                 (long) mld->align, mld->preference, load_size, 
> mld->avoid_efi_boot_services);

Too long line and lack of ",". I would like to see this:

         grub_dprintf ("multiboot_loader", "align=0x%lx, preference=0x%x, "
                       "load_size=0x%x, avoid_efi_boot_services=%d\n",
                       (long) mld->align, mld->preference, load_size,
                       mld->avoid_efi_boot_services);

>        if (load_size > mld->max_addr || mld->min_addr > mld->max_addr - 
> load_size)
>       return grub_error (GRUB_ERR_BAD_OS, "invalid min/max address and/or 
> load size");
>
> @@ -108,27 +111,21 @@ CONCAT(grub_multiboot_load_elf, XX) (mbi_load_data_t 
> *mld)
>                                             mld->min_addr, mld->max_addr - 
> load_size,
>                                             load_size, mld->align ? 
> mld->align : 1,
>                                             mld->preference, 
> mld->avoid_efi_boot_services);
> -    }
> -  else
> -    err = grub_relocator_alloc_chunk_addr (GRUB_MULTIBOOT (relocator), &ch,
> -                                        mld->link_base_addr, load_size);
>
> -  if (err)
> -    {
> -      grub_dprintf ("multiboot_loader", "Cannot allocate memory for OS 
> image\n");
> -      return err;
> -    }
> +      if (err)
> +        {
> +          grub_dprintf ("multiboot_loader", "Cannot allocate memory for OS 
> image\n");
> +          return err;
> +        }
>
> -  mld->load_base_addr = get_physical_target_address (ch);
> -  source = get_virtual_current_address (ch);
> +      mld->load_base_addr = get_physical_target_address (ch);
> +      source = get_virtual_current_address (ch);
> +    }
> +  else
> +    mld->load_base_addr = mld->link_base_addr;
>
>    grub_dprintf ("multiboot_loader", "link_base_addr=0x%x, 
> load_base_addr=0x%x, "
> -             "load_size=0x%x, relocatable=%d\n", mld->link_base_addr,
> -             mld->load_base_addr, load_size, mld->relocatable);
> -
> -  if (mld->relocatable)
> -    grub_dprintf ("multiboot_loader", "align=0x%lx, preference=0x%x, 
> avoid_efi_boot_services=%d\n",
> -               (long) mld->align, mld->preference, 
> mld->avoid_efi_boot_services);
> +             "relocatable=%d\n", mld->link_base_addr, mld->load_base_addr, 
> mld->relocatable);

I think that this would be much better:
       grub_dprintf ("multiboot_loader", "relocatable=%d, link_base_addr=0x%x, "
                     "load_base_addr=0x%x\n", mld->relocatable,
                     mld->link_base_addr, mld->load_base_addr);

As I you can see mostly nitpicks. So, I think that after next
iteration everything will be OK.

Thank you for doing the work.

Daniel