1
0

Support GUID Partition Table (GPT) disk layout

git-svn-id: svn://kolibrios.org@6827 a494cfbc-eb01-0410-851d-a64ba20cac60
This commit is contained in:
Ivan Baravy 2017-01-14 21:28:27 +00:00
parent 46ae9b5169
commit 34df6be0da
3 changed files with 312 additions and 19 deletions
kernel/trunk

View File

@ -216,6 +216,50 @@ struct PARTITION_TABLE_ENTRY
; Length of the partition in sectors.
ends
; GUID Partition Table Header, UEFI 2.6, Table 18
struct GPTH
Signature rb 8
; 'EFI PART'
Revision dd ?
; 0x00010000
HeaderSize dd ?
; Size of this header in bytes, must fit to one sector.
HeaderCRC32 dd ?
; Set this field to zero, compute CRC32 via 0xEDB88320, compare.
Reserved dd ?
; Myst be zero.
MyLBA dq ?
; LBA of the sector containing this GPT header.
AlternateLBA dq ?
; LBA of the sector containing the other GPT header.
; AlternateLBA of Primary GPTH points to Backup one and vice versa.
FirstUsableLBA dq ?
; Only sectors between first and last UsableLBA may form partitions
LastUsableLBA dq ?
DiskGUID rb 16
; Globally Unique IDentifier
PartitionEntryLBA dq ?
; First LBA of Partition Entry Array.
; Length in bytes is computed as a product of two following fields.
NumberOfPartitionEntries dd ?
; Actual number of partitions depends on the contents of Partition Entry Array.
; A partition entry is unused if zeroed.
SizeOfPartitionEntry dd ? ; in bytes
PartitionEntryArrayCRC32 dd ?
; Same CRC as for GPT header.
ends
; GPT Partition Entry, UEFI 2.6, Table 19
struct GPE
PartitionTypeGUID rb 16
UniquePartitionGUID rb 16
StartingLBA dq ?
EndingLBA dq ?
; Length in sectors is EndingLBA - StartingLBA + 1.
Attributes dq ?
PartitionName rb 72
ends
; =============================================================================
; ================================ Global data ================================
; =============================================================================
@ -667,7 +711,7 @@ disk_scan_partitions:
xor ebp, ebp ; start from sector zero
push ebp ; no extended partition yet
; 4. MBR is 512 bytes long. If sector size is less than 512 bytes,
; assume no MBR, no partitions and go to 10.
; assume no MBR, no partitions and go to 11.
cmp [esi+DISK.MediaInfo.SectorSize], 512
jb .notmbr
.new_mbr:
@ -689,9 +733,19 @@ disk_scan_partitions:
cmp word [ecx+0x40], 0xaa55
jnz .mbr_failed
; 8. The MBR is treated differently from EBRs. For MBR we additionally need to
; execute step 9 and possibly step 10.
; execute step 10 and possibly step 11.
test ebp, ebp
jnz .mbr
; 9. Handle GUID Partition Table
; 9a. Check if MBR is protective
call is_protective_mbr
jnz .no_gpt
; 9b. If so, try to scan GPT headers
call disk_scan_gpt
; 9c. If any GPT header is valid, ignore MBR
jz .done
; Otherwise process legacy/protective MBR
.no_gpt:
; The partition table can be present or not present. In the first case, we just
; read the MBR. In the second case, we just read the bootsector for a
; filesystem.
@ -703,8 +757,8 @@ disk_scan_partitions:
; byte is jmp opcode (0EBh or 0E9h), this is a bootsector which happens to
; have zeros in the place of partition table.
; C. Otherwise, this is an MBR.
; 9. Test for MBR vs bootsector.
; 9a. Check entries. If any is invalid, go to 10 (rule A).
; 10. Test for MBR vs bootsector.
; 10a. Check entries. If any is invalid, go to 11 (rule A).
call is_partition_table_entry
jc .notmbr
add ecx, 10h
@ -716,25 +770,25 @@ disk_scan_partitions:
add ecx, 10h
call is_partition_table_entry
jc .notmbr
; 9b. Check types of the entries. If at least one is nonzero, go to 11 (rule C).
; 10b. Check types of the entries. If at least one is nonzero, go to 12 (rule C).
mov al, [ecx-30h+PARTITION_TABLE_ENTRY.Type]
or al, [ecx-20h+PARTITION_TABLE_ENTRY.Type]
or al, [ecx-10h+PARTITION_TABLE_ENTRY.Type]
or al, [ecx+PARTITION_TABLE_ENTRY.Type]
jnz .mbr
; 9c. Empty partition table or bootsector with many zeroes? (rule B)
; 10c. Empty partition table or bootsector with many zeroes? (rule B)
cmp byte [ebx], 0EBh
jz .notmbr
cmp byte [ebx], 0E9h
jnz .mbr
.notmbr:
; 10. This is not an MBR. The media is not partitioned. Create one partition
; 11. This is not an MBR. The media is not partitioned. Create one partition
; which covers all the media and abort the loop.
stdcall disk_add_partition, 0, 0, \
dword [esi+DISK.MediaInfo.Capacity], dword [esi+DISK.MediaInfo.Capacity+4], esi
jmp .done
.mbr:
; 11. Process all entries of the new MBR/EBR
; 12. Process all entries of the new MBR/EBR
lea ecx, [ebx+0x1be] ; ecx -> partition table
push 0 ; assume no extended partition
call process_partition_table_entry
@ -745,12 +799,12 @@ disk_scan_partitions:
add ecx, 10h
call process_partition_table_entry
pop ebp
; 12. Test whether we found a new EBR and should continue the loop.
; 12a. If there was no next EBR, return.
; 13. Test whether we found a new EBR and should continue the loop.
; 13a. If there was no next EBR, return.
test ebp, ebp
jz .done
; Ok, we have EBR.
; 12b. EBRs addresses are relative to the start of extended partition.
; 13b. EBRs addresses are relative to the start of extended partition.
; For simplicity, just abort if an 32-bit overflow occurs; large disks
; are most likely partitioned with GPT, not MBR scheme, since the precise
; calculation here would increase limit just twice at the price of big
@ -758,34 +812,231 @@ disk_scan_partitions:
pop eax ; load extended partition
add ebp, eax
jc .mbr_failed
; 12c. If extended partition has not yet started, start it.
; 13c. If extended partition has not yet started, start it.
test eax, eax
jnz @f
mov eax, ebp
@@:
; 12c. If the limit is not exceeded, continue the loop.
; 13d. If the limit is not exceeded, continue the loop.
dec dword [esp]
push eax ; store extended partition
jnz .new_mbr
.mbr_failed:
.done:
; 13. Cleanup after the loop.
; 14. Cleanup after the loop.
pop eax ; not important anymore
pop eax ; not important anymore
pop ebp ; restore ebp
; 14. Release the buffer.
; 14a. Test whether it is the global buffer or we have allocated it.
; 15. Release the buffer.
; 15a. Test whether it is the global buffer or we have allocated it.
cmp ebx, mbr_buffer
jz .release_partition_buffer
; 14b. If we have allocated it, free it.
; 15b. If we have allocated it, free it.
xchg eax, ebx
call free
jmp .nothing
; 14c. Otherwise, release reference.
; 15c. Otherwise, release reference.
.release_partition_buffer:
lock dec [partition_buffer_users]
.nothing:
; 15. Return.
; 16. Return.
ret
; This function is called from disk_scan_partitions to validate and parse
; primary and backup GPTs.
proc disk_scan_gpt
; Scan primary GPT (second sector)
stdcall scan_gpt, 1, 0
test eax, eax
; There is no code to restore backup GPT if it's corrupt.
; Therefore just exit if Primary GPT has been parsed successfully.
jz .exit
DEBUGF 1, 'K : Primary GPT is corrupt, trying backup one\n'
mov eax, dword[esi+DISK.MediaInfo.Capacity+0]
mov edx, dword[esi+DISK.MediaInfo.Capacity+4]
sub eax, 1
sbb edx, 0
; Scan backup GPT (last sector)
stdcall scan_gpt, eax, edx
test eax, eax
jz .exit
DEBUGF 1, 'K : Backup GPT is also corrupt, fallback to legacy MBR\n'
.exit:
; Return value is ZF
ret
endp
; This function is called from disk_scan_gpt to process a single GPT.
proc scan_gpt _mylba:qword
locals
GPEA_len dd ? ; Length of GPT Partition Entry Array in bytes
endl
push ebx edi
; Allocalte memory for GPT header
mov eax, [esi+DISK.MediaInfo.SectorSize]
stdcall kernel_alloc, eax
test eax, eax
jz .fail
; Save pointer to stack, just in case
push eax
mov ebx, eax
; Read GPT header
mov al, DISKFUNC.read
push 1
stdcall disk_call_driver, ebx, dword[_mylba+0], dword[_mylba+4], esp
pop ecx
test eax, eax
jnz .fail_free_gpt
; Check signature
cmp dword[ebx+GPTH.Signature+0], 'EFI '
jnz .fail_free_gpt
cmp dword[ebx+GPTH.Signature+4], 'PART'
jnz .fail_free_gpt
; Check Revision
cmp [ebx+GPTH.Revision], 0x00010000
jnz .fail_free_gpt
; Compute and check CRC32
xor edx, edx
xchg edx, [ebx+GPTH.HeaderCRC32]
mov eax, -1
stdcall crc_32, 0xEDB88320, ebx, [ebx+GPTH.HeaderSize]
xor eax, -1
cmp eax, edx
jnz .fail_free_gpt
; Reserved must be zero
cmp [ebx+GPTH.Reserved], 0
jnz .fail_free_gpt
; MyLBA of GPT header at LBA X must equal X
mov eax, dword[ebx+GPTH.MyLBA+0]
mov edx, dword[ebx+GPTH.MyLBA+4]
cmp eax, dword[_mylba+0]
jnz .fail_free_gpt
cmp edx, dword[_mylba+4]
jnz .fail_free_gpt
; Capacity - MyLBA = AlternateLBA
mov eax, dword[esi+DISK.MediaInfo.Capacity+0]
mov edx, dword[esi+DISK.MediaInfo.Capacity+4]
sub eax, dword[_mylba+0]
sbb edx, dword[_mylba+4]
cmp eax, dword[ebx+GPTH.AlternateLBA+0]
; DISK.MediaInfo.Capacity is -1 for ATA devices, disable this check for now.
; jnz .fail_free_gpt
cmp edx, dword[ebx+GPTH.AlternateLBA+4]
; jnz .fail_free_gpt
; Compute GPT Partition Entry Array (GPEA) length in bytes
mov eax, [ebx+GPTH.NumberOfPartitionEntries]
mul [ebx+GPTH.SizeOfPartitionEntry]
test edx, edx ; far too big
jnz .fail_free_gpt
; Round up to sector boundary
mov ecx, [esi+DISK.MediaInfo.SectorSize] ; power of two
dec ecx
add eax, ecx
jc .fail_free_gpt ; too big
not ecx
and eax, ecx
; We will need this length to compute CRC32 of GPEA
mov [GPEA_len], eax
; Allocate memory for GPEA
stdcall kernel_alloc, eax
test eax, eax
jz .fail_free_gpt
; Save to not juggle with registers
push eax
mov edi, eax
mov eax, [GPEA_len]
xor edx, edx
; Get the number of sectors GPEA fits into
div [esi+DISK.MediaInfo.SectorSize]
push eax ; esp = pointer to the number of sectors
mov al, DISKFUNC.read
stdcall disk_call_driver, edi, dword[ebx+GPTH.PartitionEntryLBA+0], \
dword[ebx+GPTH.PartitionEntryLBA+4], esp
pop ecx
test eax, eax
jnz .fail_free_gpea_gpt
; Compute and check CRC32 of GPEA
mov edx, [ebx+GPTH.PartitionEntryArrayCRC32]
mov eax, -1
stdcall crc_32, 0xEDB88320, edi, [GPEA_len]
xor eax, -1
cmp eax, edx
jnz .fail_free_gpea_gpt
; Process partitions, skip zeroed ones.
.next_gpe:
xor eax, eax
mov ecx, [ebx+GPTH.SizeOfPartitionEntry]
repz scasb
jz .skip
add edi, ecx
sub edi, [ebx+GPTH.SizeOfPartitionEntry]
; Length of a partition in sectors is EndingLBA - StartingLBA + 1
mov eax, dword[edi+GPE.EndingLBA+0]
mov edx, dword[edi+GPE.EndingLBA+4]
sub eax, dword[edi+GPE.StartingLBA+0]
sbb edx, dword[edi+GPE.StartingLBA+4]
add eax, 1
adc edx, 0
stdcall disk_add_partition, dword[edi+GPE.StartingLBA+0], \
dword[edi+GPE.StartingLBA+4], eax, edx, esi
add edi, [ebx+GPTH.SizeOfPartitionEntry]
.skip:
dec [ebx+GPTH.NumberOfPartitionEntries]
jnz .next_gpe
; Pointers to GPT header and GPEA are on the stack
stdcall kernel_free
stdcall kernel_free
pop edi ebx
xor eax, eax
ret
.fail_free_gpea_gpt:
stdcall kernel_free
.fail_free_gpt:
stdcall kernel_free
.fail:
pop edi ebx
xor eax, eax
inc eax
ret
endp
; ecx = pointer to partition records array (MBR + 446)
is_protective_mbr:
push ecx edi
xor eax, eax
cmp [ecx-6], eax
jnz .exit
cmp [ecx-2], eax
jnz .exit
; Partition record 0 has specific fields
cmp dword[ecx+0], 0x00020000
jnz .exit
cmp byte[ecx+4], 0xEE
jnz .exit
cmp dword[ecx+8], 1
jnz .exit
; DISK.MediaInfo.Capacity is -1 for ATA devices, disable this check for now.
; cmp dword[esi+DISK.MediaInfo.Capacity+4], eax
; mov edi, 0xFFFFFFFF
; jnz @f
; mov edi, dword[esi+DISK.MediaInfo.Capacity+0]
; dec edi
;@@:
; cmp dword[ecx+12], edi
; jnz .exit
; Check that partition records 1-3 are filled with zero
lea edi, [ecx+16]
mov ecx, 16*3/2 ; 3 partitions
repz scasw
.exit:
pop edi ecx
; Return value is ZF
ret
; This is an internal function called from disk_scan_partitions. It checks

40
kernel/trunk/crc.inc Normal file
View File

@ -0,0 +1,40 @@
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; ;;
;; Copyright (C) KolibriOS team 2004-2017. All rights reserved. ;;
;; Distributed under terms of the GNU General Public License. ;;
;; ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; This crc32 routine doesn't use precomputed table to allow different
; polynomials, which is the first param.
; Partial hash in assumed to be eax (both in and out).
; Usage:
; 1. mov eax, -1
; 2. stdcall crypto.crc32 zero or more times
; 3. xor eax, -1
proc crc_32 _poly, _buffer, _length
push ebx ecx edx esi
mov esi, [_buffer]
.next_byte:
dec [_length]
js .done
movzx ebx, byte[esi]
inc esi
mov ecx, 8
.next_bit:
mov edx, eax
xor edx, ebx
shr eax, 1
test edx, 1
jz @f
xor eax, [_poly]
@@:
shr ebx, 1
dec ecx
jnz .next_bit
jmp .next_byte
.done:
pop esi edx ecx ebx
ret
endp

View File

@ -65,6 +65,8 @@ include "fs/fs_lfn.inc" ; sysfunction 70
include "network/stack.inc"
include "crc.inc" ; checksums
; include "imports.inc"
; include "core/ext_lib.inc"
; include "core/conf_lib.inc"