Re: [PATCH V3 3/3] Update Linux loader to follow the kernel's preferences

["Vladimir 'φ-coder/phcoder' Serbinenko" <phcoder@gmail.com>]

On 08.02.2012 17:55, Matthew Garrett wrote:
> We should attempt to load the kernel at its preferred address, and if we
> can't do that then we should at lesat align it correctly. When doing so
> we should also make sure to avoid putting the kernel on top of any regions
> being used by the firmware.
> ---
>   ChangeLog                     |    8 +++++
>   grub-core/loader/i386/linux.c |   67 ++++++++++++++++++++++++++++++++++------
>   2 files changed, 65 insertions(+), 10 deletions(-)
>
> diff --git a/ChangeLog b/ChangeLog
> index 8bef256..162f82b 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,5 +1,13 @@
>   2012-02-08  Matthew Garrett<mjg@redhat.com>
>
> +	* grub-core/loader/i386/linux.c (allocate_pages): Attempt to obtain
> +	appropriately aligned memory if the desired target is unavailable
> +	(grub_cmd_linux): Update to match newer Linux boot protocols, and
> +	attempt to load the kernel at its preferred address rather than
> +	hardcoding.
> +
> +2012-02-08  Matthew Garrett<mjg@redhat.com>
> +
>   	* grub-core/lib/efi/relocator.c (grub_relocator_alloc_chunk_addr):
>   	Add argument to fail allocation when target address overlaps
>   	firmware regions. All users updated.
> diff --git a/grub-core/loader/i386/linux.c b/grub-core/loader/i386/linux.c
> index 67a4533..3eb8fa0 100644
> --- a/grub-core/loader/i386/linux.c
> +++ b/grub-core/loader/i386/linux.c
> @@ -183,13 +183,14 @@ free_pages (void)
>     grub_relocator_unload (relocator);
>     relocator = NULL;
>     real_mode_mem = prot_mode_mem = initrd_mem = 0;
> -  real_mode_target = prot_mode_target = initrd_mem_target = 0;
> +  real_mode_target = initrd_mem_target = 0;
Any reason not to clean prot_mode_target? Looks like you wanted to 
remove its use. If so, can you remove declaration as well?
> @@ -269,18 +270,38 @@ allocate_pages (grub_size_t prot_size)
>   					    + efi_mmap_size), 0);
>       if (err)
>         goto fail;
> +
> +    grub_errno = GRUB_ERR_NONE;
Why do you reset error here?
>       real_mode_mem = get_virtual_current_address (ch);
>     }
>     efi_mmap_buf = (grub_uint8_t *) real_mode_mem + real_size + mmap_size;
>
> -  prot_mode_target = GRUB_LINUX_BZIMAGE_ADDR;
> -
>     {
>       grub_relocator_chunk_t ch;
>       err = grub_relocator_alloc_chunk_addr (relocator,&ch,
> -					   prot_mode_target, prot_size, 0);
> +					   prot_mode_target, prot_size,
> +					   relocatable);
> +    if (err)
> +      {
> +	unsigned int i;
> +	for (i = *align; i>= min_align; i--)
> +	  {
I see here no check that kernel is relocatable.
> +	    err = grub_relocator_alloc_chunk_align (relocator,&ch,
> +						    0x1000000, 0xffffffff,
> +						    prot_size, 1<<  i,
> +						    GRUB_RELOCATOR_PREFERENCE_LOW);
> +	    if (!err)
> +	      {
> +		*align = i;
> +		prot_mode_target = get_physical_target_address (ch);
> +		break;
> +	      }
Here you need to clean grub_errno since you ignore error
> +	  }
> +      }
> +
You need to restore grub_errno here (you can use grub_error_save and 
grub_error_load).
>       if (err)
>         goto fail;
> +
>       prot_mode_mem = get_virtual_current_address (ch);
>     }
>
> @@ -631,8 +652,9 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
>     struct linux_kernel_header lh;
>     struct linux_kernel_params *params;
>     grub_uint8_t setup_sects;
> -  grub_size_t real_size, prot_size;
> +  grub_size_t real_size, prot_size, prot_file_size, align = 0, min_align = 0;
>     grub_ssize_t len;
> +  int relocatable = 0;
>     int i;
>
>     grub_dl_ref (my_mod);
> @@ -705,9 +727,32 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
>       setup_sects = GRUB_LINUX_DEFAULT_SETUP_SECTS;
>
>     real_size = setup_sects<<  GRUB_DISK_SECTOR_BITS;
> -  prot_size = grub_file_size (file) - real_size - GRUB_DISK_SECTOR_SIZE;
>
> -  if (allocate_pages (prot_size))
> +  if (grub_le_to_cpu16 (lh.version)>= 0x205)
> +    {
> +      for (align = 0; align<  32; align++)
> +	{
> +	  if (grub_le_to_cpu32 (lh.kernel_alignment)&  (1<<  align))
> +	    break;
> +	}
> +      relocatable = grub_le_to_cpu32 (lh.relocatable);
> +    }
> +
> +  if (grub_le_to_cpu16 (lh.version)>= 0x020a)
> +    {
> +      min_align = lh.min_alignment;
> +      prot_size = grub_le_to_cpu32 (lh.init_size);
> +      prot_mode_target = grub_le_to_cpu64 (lh.pref_address);
> +    }
> +  else
> +    {
> +      min_align = 0;
> +      prot_size = grub_file_size (file) - real_size - GRUB_DISK_SECTOR_SIZE;
> +      prot_mode_target = grub_le_to_cpu32 (lh.code32_start);
> +    }
> +
> +  prot_file_size = grub_file_size (file) - real_size - GRUB_DISK_SECTOR_SIZE;
> +  if (allocate_pages (prot_size,&align, min_align, relocatable))
>       goto fail;
>
>     params = (struct linux_kernel_params *) real_mode_mem;
> @@ -715,6 +760,8 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
>     grub_memcpy (&params->setup_sects,&lh.setup_sects, sizeof (lh) - 0x1F1);
>
>     params->ps_mouse = params->padding10 =  0;
> +  params->code32_start = prot_mode_target;
> +  params->kernel_alignment = (1<<  align);
>
>     len = 0x400 - sizeof (lh);
>     if (grub_file_read (file, (char *) real_mode_mem + sizeof (lh), len) != len)
> @@ -774,7 +821,7 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
>     grub_file_seek (file, real_size + GRUB_DISK_SECTOR_SIZE);
>
>     grub_dprintf ("linux", "bzImage, setup=0x%x, size=0x%x\n",
> -		(unsigned) real_size, (unsigned) prot_size);
> +		(unsigned) real_size, (unsigned) prot_file_size);
>
>     /* Look for memory size and video mode specified on the command line.  */
>     linux_mem_size = 0;
> @@ -911,7 +958,7 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
>   			      maximal_cmdline_size
>   			      - (sizeof (LINUX_IMAGE) - 1));
>
> -  len = prot_size;
> +  len = prot_file_size;
Any reason for rename?
>     if (grub_file_read (file, prot_mode_mem, len) != len&&  !grub_errno)
>       grub_error (GRUB_ERR_FILE_READ_ERROR, N_("premature end of file %s"),
>   		argv[0]);
> -- 1.7.7.6 _______________________________________________ Grub-devel 
> mailing list Grub-devel@gnu.org 
> https://lists.gnu.org/mailman/listinfo/grub-devel


-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko