[PATCH SLOF v3 5/5] disk-label: add support for booting from GPT FAT partition
Nikunj A Dadhania
nikunj at linux.vnet.ibm.com
Tue Jun 30 22:24:14 AEST 2015
Thomas Huth <thuth at redhat.com> writes:
> Sorry, every time I look at this gpt stuff, my eyes stumble
> over something new ...
No worries :-)
> On Tue, 30 Jun 2015 16:31:21 +0530
> Nikunj A Dadhania <nikunj at linux.vnet.ibm.com> wrote:
>
>> For a GPT+LVM combination disk, older bootloader that does not support
>> LVM, cannot load kernel from LVM.
>>
>> The patch adds support to read from BASIC_DATA UUID partitions for the
>> case that the OS installer has installed the CHRP-BOOT config on a FAT
>> file system.
>>
>> Makes GPT detection robust
>> * Check for Protective MBR Magic
>> * Check for valid GPT Signature
>> * Boundary check for allocated block size before reading into the
>> buffer
>>
>> Signed-off-by: Nikunj A Dadhania <nikunj at linux.vnet.ibm.com>
>> ---
>> slof/fs/packages/disk-label.fs | 99 +++++++++++++++++++++++++++++++++---------
>> 1 file changed, 79 insertions(+), 20 deletions(-)
>>
>> diff --git a/slof/fs/packages/disk-label.fs b/slof/fs/packages/disk-label.fs
>> index 347dc5d..5267ddb 100644
>> --- a/slof/fs/packages/disk-label.fs
>> +++ b/slof/fs/packages/disk-label.fs
> ...
>> +\ The routine checks whether the protective MBR has GPT ID and then
>> +\ reads the gpt data from the sector. Also set the seek position and
>> +\ the partition size used in caller routines.
>> +
>> +: get-gpt-partition ( -- true|false )
>> + no-gpt? IF false EXIT THEN
>> + debug-disk-label? IF cr ." GPT partition found " cr THEN
>> + 1 read-disk-buf
>> + disk-buf gpt>part-entry-lba x at -le
>> block-size * to seek-pos
>> disk-buf gpt>part-entry-size l at -le to gpt-part-size
>> - disk-buf gpt>num-part-entry l at -le dup 0= IF false EXIT THEN
>> + gpt-part-size disk-buf-size > IF
>> + cr ." GPT part size exceeds buffer allocated " cr
>> + false exit
>> + THEN
>> + disk-buf gpt>signature x@ GPT-SIGNATURE =
>> +;
>> +
>> +: load-from-gpt-prep-partition ( addr -- size )
>> + get-gpt-partition 0= IF false EXIT THEN
>> + disk-buf gpt>num-part-entry l at -le dup 0= IF false exit THEN
>> 1+ 1 ?DO
>> seek-pos 0 seek drop
>> disk-buf gpt-part-size read drop gpt-prep-partition? IF
>> - debug-disk-label? IF
>> - ." GPT PReP partition found " cr
>> - THEN
>> - disk-buf gpt-part-entry>first-lba x at -le
>> - disk-buf gpt-part-entry>last-lba x at -le
>> - over - 1+ ( addr offset len )
>> - swap ( addr len offset )
>> - block-size * to part-offset
>> - 0 0 seek drop ( addr len )
>> - block-size * read ( size )
>> + debug-disk-label? IF ." GPT PReP partition found " cr THEN
>> + disk-buf gpt-part-entry>first-lba x at -le ( addr first-lba )
>> + disk-buf gpt-part-entry>last-lba x at -le ( addr first-lba last-lba)
>> + over - 1+ ( addr first-lba blocks )
>> + swap ( addr blocks first-lba )
>> + block-size * to part-offset ( addr blocks )
>> + 0 0 seek drop ( addr blocks )
>> + block-size * read ( size )
>> + UNLOOP EXIT
>> + THEN
>> + seek-pos gpt-part-size i * + to seek-pos
>
> Is this the right way to update the seek pos?
Good catch !! its jumping ahead, should go in the order of 128byte
(gpt-part-size)
> Looks somewhat suspicious
> to me, shouldn't this rather be:
>
> seek-pos gpt-part-size + to seek-pos
Would use this. Updated patch attached.
> or maybe if you store the base value somewhere instead, something like:
>
> seek-pos-base gpt-part-size i * + to seek-pos
>
> ?
>
>> + LOOP
>> + false
>> +;
>> +
>> +: try-gpt-dos-partition ( -- true|false )
>> + get-gpt-partition 0= IF false EXIT THEN
>> + disk-buf gpt>num-part-entry l at -le dup 0= IF false EXIT THEN
>> + 1+ 1 ?DO
>> + seek-pos 0 seek drop
>> + disk-buf gpt-part-size read drop
>> + gpt-basic-data-partition? IF
>> + debug-disk-label? IF ." GPT BASIC DATA partition found " cr THEN
>> + disk-buf gpt-part-entry>first-lba x at -le ( first-lba )
>> + dup to part-start ( first-lba )
>> + disk-buf gpt-part-entry>last-lba x at -le ( first-lba last-lba )
>> + over - 1+ ( first-lba s1 )
>> + block-size * to part-size ( first-lba )
>> + block-size * to part-offset ( )
>> + 0 0 seek drop
>> + disk-buf block-size read drop
>> + disk-buf fat-bootblock? ( true|false )
>> UNLOOP EXIT
>> THEN
>> seek-pos gpt-part-size i * + to seek-pos
>
> dito (so this bug was likely there before?)
Seems was working because it happens to be the first partition. If not
would have failed.
disk-label: add support for booting from GPT FAT partition
For a GPT+LVM combination disk, older bootloader that does not support
LVM, cannot load kernel from LVM.
The patch adds support to read from BASIC_DATA UUID partitions for the
case that the OS installer has installed the CHRP-BOOT config on a FAT
file system.
Makes GPT detection robust
* Fix bug in seek-pos updation code
* Check for Protective MBR Magic
* Check for valid GPT Signature
* Boundary check for allocated block size before reading into the
buffer
Signed-off-by: Nikunj A Dadhania <nikunj at linux.vnet.ibm.com>
diff --git a/slof/fs/packages/disk-label.fs b/slof/fs/packages/disk-label.fs
index 347dc5d..fa5df27 100644
--- a/slof/fs/packages/disk-label.fs
+++ b/slof/fs/packages/disk-label.fs
@@ -179,7 +179,8 @@ CONSTANT /gpt-part-entry
\ This word returns true if the currently loaded disk-buf has _NO_ GPT partition id
: no-gpt? ( -- true|false )
0 read-disk-buf
- 1 partition>part-entry part-entry>id c@ ee <>
+ 1 partition>part-entry part-entry>id c@ ee <> IF true EXIT THEN
+ disk-buf mbr>magic w at -le aa55 <>
;
: pc-extended-partition? ( part-entry-addr -- true|false )
@@ -267,7 +268,10 @@ CONSTANT /gpt-part-entry
: try-dos-partition ( -- okay? )
\ Read partition table and check magic.
- no-mbr? IF cr ." No DOS disk-label found." cr false EXIT THEN
+ no-mbr? IF
+ debug-disk-label? IF cr ." No DOS disk-label found." cr THEN
+ false EXIT
+ THEN
count-dos-logical-partitions TO dos-logical-partitions
@@ -377,31 +381,85 @@ AA268B49521E5A8B CONSTANT GPT-PREP-PARTITION-4
8 + x@ GPT-PREP-PARTITION-4 =
;
-: load-from-gpt-prep-partition ( addr -- size )
- no-gpt? IF drop false EXIT THEN
- debug-disk-label? IF
- cr ." GPT partition found " cr
- THEN
- 1 read-disk-buf disk-buf gpt>part-entry-lba l at -le
+\ Check for GPT MSFT BASIC DATA GUID - fat based
+EBD0A0A2 CONSTANT GPT-BASIC-DATA-PARTITION-1
+B9E5 CONSTANT GPT-BASIC-DATA-PARTITION-2
+4433 CONSTANT GPT-BASIC-DATA-PARTITION-3
+87C068B6B72699C7 CONSTANT GPT-BASIC-DATA-PARTITION-4
+
+: gpt-basic-data-partition? ( -- true|false )
+ disk-buf gpt-part-entry>part-type-guid
+ dup l at -le GPT-BASIC-DATA-PARTITION-1 <> IF drop false EXIT THEN
+ dup 4 + w at -le GPT-BASIC-DATA-PARTITION-2 <> IF drop false EXIT THEN
+ dup 6 + w at -le GPT-BASIC-DATA-PARTITION-3 <> IF drop false EXIT THEN
+ 8 + x@ GPT-BASIC-DATA-PARTITION-4 =
+;
+
+\
+\ GPT Signature
+\ ("EFI PART", 45h 46h 49h 20h 50h 41h 52h 54h)
+\
+4546492050415254 CONSTANT GPT-SIGNATURE
+
+\ The routine checks whether the protective MBR has GPT ID and then
+\ reads the gpt data from the sector. Also set the seek position and
+\ the partition size used in caller routines.
+
+: get-gpt-partition ( -- true|false )
+ no-gpt? IF false EXIT THEN
+ debug-disk-label? IF cr ." GPT partition found " cr THEN
+ 1 read-disk-buf
+ disk-buf gpt>part-entry-lba x at -le
block-size * to seek-pos
disk-buf gpt>part-entry-size l at -le to gpt-part-size
- disk-buf gpt>num-part-entry l at -le dup 0= IF false EXIT THEN
+ gpt-part-size disk-buf-size > IF
+ cr ." GPT part size exceeds buffer allocated " cr
+ false exit
+ THEN
+ disk-buf gpt>signature x@ GPT-SIGNATURE =
+;
+
+: load-from-gpt-prep-partition ( addr -- size )
+ get-gpt-partition 0= IF false EXIT THEN
+ disk-buf gpt>num-part-entry l at -le dup 0= IF false exit THEN
1+ 1 ?DO
seek-pos 0 seek drop
disk-buf gpt-part-size read drop gpt-prep-partition? IF
- debug-disk-label? IF
- ." GPT PReP partition found " cr
- THEN
- disk-buf gpt-part-entry>first-lba x at -le
- disk-buf gpt-part-entry>last-lba x at -le
- over - 1+ ( addr offset len )
- swap ( addr len offset )
- block-size * to part-offset
- 0 0 seek drop ( addr len )
- block-size * read ( size )
+ debug-disk-label? IF ." GPT PReP partition found " cr THEN
+ disk-buf gpt-part-entry>first-lba x at -le ( addr first-lba )
+ disk-buf gpt-part-entry>last-lba x at -le ( addr first-lba last-lba)
+ over - 1+ ( addr first-lba blocks )
+ swap ( addr blocks first-lba )
+ block-size * to part-offset ( addr blocks )
+ 0 0 seek drop ( addr blocks )
+ block-size * read ( size )
+ UNLOOP EXIT
+ THEN
+ seek-pos gpt-part-size + to seek-pos
+ LOOP
+ false
+;
+
+: try-gpt-dos-partition ( -- true|false )
+ get-gpt-partition 0= IF false EXIT THEN
+ disk-buf gpt>num-part-entry l at -le dup 0= IF false EXIT THEN
+ 1+ 1 ?DO
+ seek-pos 0 seek drop
+ disk-buf gpt-part-size read drop
+ gpt-basic-data-partition? IF
+ debug-disk-label? IF ." GPT BASIC DATA partition found " cr THEN
+ disk-buf gpt-part-entry>first-lba x at -le ( first-lba )
+ dup to part-start ( first-lba )
+ disk-buf gpt-part-entry>last-lba x at -le ( first-lba last-lba )
+ over - 1+ ( first-lba s1 )
+ block-size * to part-size ( first-lba )
+ block-size * to part-offset ( )
+ 0 0 seek drop
+ disk-buf block-size read drop
+ disk-buf fat-bootblock? ( true|false )
UNLOOP EXIT
THEN
- seek-pos gpt-part-size i * + to seek-pos
+ seek-pos gpt-part-size + to seek-pos
LOOP
false
;
@@ -491,7 +549,7 @@ AA268B49521E5A8B CONSTANT GPT-PREP-PARTITION-4
debug-disk-label? IF ." Trying CHRP boot " .s cr THEN
1 disk-chrp-boot !
- dup load-chrp-boot-file ?dup 0 <> IF .s cr nip EXIT THEN
+ dup load-chrp-boot-file ?dup 0 <> IF nip EXIT THEN
0 disk-chrp-boot !
debug-disk-label? IF ." Trying GPT boot " .s cr THEN
@@ -591,6 +649,7 @@ AA268B49521E5A8B CONSTANT GPT-PREP-PARTITION-4
: try-partitions ( -- found? )
try-dos-partition IF try-files EXIT THEN
+ try-gpt-dos-partition IF try-files EXIT THEN
\ try-iso9660-partition IF try-files EXIT THEN
\ ... more partition types here...
false
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