Re: [PATCH V2 3/3] Update Linux loader to follow the kernel's preferences

[Keshav P R]

On Mon, Feb 6, 2012 at 21:58, Keshav P R <address@hidden> wrote:
> On Mon, Feb 6, 2012 at 21:23, Matthew Garrett <address@hidden> 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.
>> ---
>>
>> I managed to screw up the rebase, so this is a fixed version. Also, the code
>> now follows the old path if the kernel isn't relocatable - we can't move it,
>> so better to try it and just hope that everything works out.
>>
>>  ChangeLog                     |    8 +++++
>>  grub-core/loader/i386/linux.c |   67 
>> ++++++++++++++++++++++++++++++++++------
>>  2 files changed, 65 insertions(+), 10 deletions(-)
>>
>> diff --git a/ChangeLog b/ChangeLog
>> index 33e5dda..aedf4bc 100644
>> --- a/ChangeLog
>> +++ b/ChangeLog
>> @@ -1,5 +1,13 @@
>>  2012-02-06  Matthew Garrett  <address@hidden>
>>
>> +       * 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.
>> +
>> +2012-02-06  Matthew Garrett  <address@hidden>
>> +
>>        * 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;
>>  }
>>
>>  /* Allocate pages for the real mode code and the protected mode code
>>    for linux as well as a memory map buffer.  */
>>  static grub_err_t
>> -allocate_pages (grub_size_t prot_size)
>> +allocate_pages (grub_size_t prot_size, grub_size_t *align,
>> +               grub_size_t min_align, int relocatable)
>>  {
>>   grub_size_t real_size, mmap_size;
>>   grub_err_t err;
>> @@ -269,18 +270,38 @@ allocate_pages (grub_size_t prot_size)
>>                                            + efi_mmap_size), 0);
>>     if (err)
>>       goto fail;
>> +
>> +    grub_errno = GRUB_ERR_NONE;
>>     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--)
>> +         {
>> +           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;
>> +             }
>> +         }
>> +      }
>> +
>>     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;
>>   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
>> address@hidden
>> https://lists.gnu.org/mailman/listinfo/grub-devel
>
> Boot fine in VirtualBox X64 UEFI (UEFI 2.1 Tianocore OVMF). Patch V1
> 3/3 failed with premature end of file error.
>
> Regards.
>
> Keshav

Compile error for grub2-bios (i386-pc target)

gcc -DHAVE_CONFIG_H -I. -I..  -Wall -W -I../include -I../include
-DGRUB_MACHINE_PCBIOS=1 -DGRUB_MACHINE=I386_PC
-DGRUB_TARGET_CPU_I386=1 -m32 -nostdinc -isystem
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/include
-DGRUB_FILE=\"loader/i386/pc/plan9.c\" -I. -I. -I.. -I.. -I../include
-I../include     -Os -Wall -W -Wshadow -Wpointer-arith
-Wmissing-prototypes -Wundef -Wstrict-prototypes -g -falign-jumps=1
-falign-loops=1 -falign-functions=1 -mno-mmx -mno-sse -mno-sse2
-mno-3dnow -fno-dwarf2-cfi-asm -fno-asynchronous-unwind-tables -m32
-fno-stack-protector -mno-stack-arg-probe -Wno-trampolines
-DUSE_ASCII_FAILBACK=1 -DHAVE_UNIFONT_WIDTHSPEC=1  -mrtd -mregparm=3
    -ffreestanding   -MT loader/i386/pc/plan9_module-plan9.o -MD -MP
-MF loader/i386/pc/.deps-core/plan9_module-plan9.Tpo -c -o
loader/i386/pc/plan9_module-plan9.o `test -f 'loader/i386/pc/plan9.c'
|| echo './'`loader/i386/pc/plan9.c
loader/i386/pc/plan9.c: In function 'grub_cmd_plan9':
loader/i386/pc/plan9.c:420:9: error: too few arguments to function
'grub_relocator_alloc_chunk_addr'
../include/grub/relocator.h:34:1: note: declared here
loader/i386/pc/plan9.c:451:9: error: too few arguments to function
'grub_relocator_alloc_chunk_addr'
../include/grub/relocator.h:34:1: note: declared here
make[3]: *** [loader/i386/pc/plan9_module-plan9.o] Error 1


with all the three V2 patches applied in order (didn't try V1). No
error in x86_64-efi compile.

- Keshav