On Thu, 25 Jun 2015 12:15:29 +0530
Nikunj A Dadhania <nik...@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 <nik...@linux.vnet.ibm.com>
> ---
> slof/fs/packages/disk-label.fs | 96
> +++++++++++++++++++++++++++++++++---------
> 1 file changed, 76 insertions(+), 20 deletions(-)
>
> diff --git a/slof/fs/packages/disk-label.fs b/slof/fs/packages/disk-label.fs
> index 7ed5526..e5759a3 100644
> --- a/slof/fs/packages/disk-label.fs
> +++ b/slof/fs/packages/disk-label.fs
...
> @@ -378,29 +382,80 @@ AA268B49521E5A8B CONSTANT GPT-PREP-PARTITION-4
> true
> ;
>
> -: 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@-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@-le GPT-BASIC-DATA-PARTITION-1 <> IF drop false EXIT THEN
> + dup 4 + w@-le GPT-BASIC-DATA-PARTITION-2 <> IF drop false EXIT THEN
> + dup 6 + w@-le GPT-BASIC-DATA-PARTITION-3 <> IF drop false EXIT THEN
> + 8 + x@ GPT-BASIC-DATA-PARTITION-4 <> IF false EXIT THEN
> + true
> +;
You could remove the "<> IF false EXIT THEN true" at the end and
replace it with a simple "=".
> +\
> +\ GPT Signature
> +\ ("EFI PART", 45h 46h 49h 20h 50h 41h 52h 54h)
> +\
> +4546492050415254 CONSTANT GPT-SIGNATURE
> +
> +: verify-gpt-partition ( -- true | false )
I'd prefer if you could write "true|false" without spaces around the
"|" so that it is clear at a glance that there is only one item on the
stack.
Could you maybe also add a comment above the function that it sets up
gpt-part-size with the size of partition entry and seek-pos with the
position of the partition entry? ...since these are non-obvious
side-effect of this function... All in all, maybe you should also name
the function differently, since it does more than just verifying.
> + 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@-le
> block-size * to seek-pos
> disk-buf gpt>part-entry-size l@-le to gpt-part-size
> - disk-buf gpt>num-part-entry l@-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 )
> + verify-gpt-partition 0= IF false EXIT THEN
> + disk-buf gpt>num-part-entry l@-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@-le
> - disk-buf gpt-part-entry>last-lba x@-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@-le ( addr first-lba )
> + disk-buf gpt-part-entry>last-lba x@-le ( addr first-lba last-lba)
> + over - 1+ ( addr first-lba blocks )
> + swap ( addr blocks )
The stack comment looks wrong here, should this be:
( 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
> + LOOP
> + false
> +;
> +
> +: try-gpt-dos-partition ( -- true | false )
"true | false" --> "true|false" ?
> + verify-gpt-partition 0= IF false EXIT THEN
> + disk-buf gpt>num-part-entry l@-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 LINUX DATA partition found " cr THEN
I think that string should maybe rather talk about "basic data
partition" instead of "LINUX data partition" ?
> + disk-buf gpt-part-entry>first-lba x@-le ( first-lba )
> + dup to part-start ( first-lba )
> + disk-buf gpt-part-entry>last-lba x@-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? 0= IF false UNLOOP EXIT THEN
> + true UNLOOP EXIT
You could simplify the above two lines to:
disk-buf fat-bootblock?
UNLOOP EXIT
> THEN
> seek-pos gpt-part-size i * + to seek-pos
> LOOP
> @@ -492,7 +547,7 @@ 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
> @@ -592,6 +647,7 @@ 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
Thomas
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