Re: mmotm-1113: efi.c: __divdi3 undefined (i386)

[Randy Dunlap]

On Mon, 16 Nov 2009 13:19:57 +0100 Karel Zak wrote:

> On Sun, Nov 15, 2009 at 10:46:31AM -0800, Randy Dunlap wrote:
> > on i386 builds:
> > 
> > fs/built-in.o: In function `last_lba':
> > efi.c:(.text+0x9d9fe): undefined reference to `__divdi3'
> > 
> > 
> > -       return (bdev->bd_inode->i_size >> 9) - 1ULL;
> > +       return (bdev->bd_inode->i_size / bdev_logical_block_size(bdev)) - 1ULL;
> 
>  Ah.. I guess that div_u64() is more portable. Updated
>  partitions-use-sector-size-for-efi-gpt.patch is below.
> 
>     Karel

Acked-by: Randy Dunlap <randy.dunlap@xxxxxxxxxx>

Thanks.



> From fbb0c11cf349545f2499d382469749543fdc03d0 Mon Sep 17 00:00:00 2001
> From: Karel Zak <kzak@xxxxxxxxxx>
> Date: Mon, 16 Nov 2009 12:19:25 +0100
> Subject: [PATCH] partitions: use sector size for EFI GPT
> 
> Currently, kernel uses strictly 512-byte sectors for EFI GPT parsing.
> That's wrong.
> 
> UEFI standard (version 2.3, May 2009, 5.3.1 GUID Format overview, page
> 95) defines that LBA is always based on the logical block size. It
> means bdev_logical_block_size() (aka BLKSSZGET) for Linux.
> 
> This patch removes static sector size from EFI GPT parser.
> 
> The problem is reproducible with the latest GNU Parted:
> 
>  # modprobe scsi_debug dev_size_mb=50 sector_size=4096
> 
>   # ./parted /dev/sdb print
>   Model: Linux scsi_debug (scsi)
>   Disk /dev/sdb: 52.4MB
>   Sector size (logical/physical): 4096B/4096B
>   Partition Table: gpt
> 
>   Number  Start   End     Size    File system  Name     Flags
>    1      24.6kB  3002kB  2978kB               primary
>    2      3002kB  6001kB  2998kB               primary
>    3      6001kB  9003kB  3002kB               primary
> 
>   # blockdev --rereadpt /dev/sdb
>   # dmesg | tail -1
>    sdb: unknown partition table      <---- !!!
> 
> with this patch:
> 
>   # blockdev --rereadpt /dev/sdb
>   # dmesg | tail -1
>    sdb: sdb1 sdb2 sdb3
> 
> Signed-off-by: Karel Zak <kzak@xxxxxxxxxx>
> Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
> ---
>  fs/partitions/efi.c |   23 +++++++++++++++--------
>  1 files changed, 15 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/partitions/efi.c b/fs/partitions/efi.c
> index 038a602..80eeff5 100644
> --- a/fs/partitions/efi.c
> +++ b/fs/partitions/efi.c
> @@ -1,7 +1,9 @@
>  /************************************************************
>   * EFI GUID Partition Table handling
> - * Per Intel EFI Specification v1.02
> - * http://developer.intel.com/technology/efi/efi.htm
> + *
> + * http://www.uefi.org/specs/
> + * http://www.intel.com/technology/efi/
> + *
>   * efi.[ch] by Matt Domsch <Matt_Domsch@xxxxxxxx>
>   *   Copyright 2000,2001,2002,2004 Dell Inc.
>   *
> @@ -92,6 +94,7 @@
>   *
>   ************************************************************/
>  #include <linux/crc32.h>
> +#include <linux/math64.h>
>  #include "check.h"
>  #include "efi.h"
>  
> @@ -141,7 +144,8 @@ last_lba(struct block_device *bdev)
>  {
>  	if (!bdev || !bdev->bd_inode)
>  		return 0;
> -	return (bdev->bd_inode->i_size >> 9) - 1ULL;
> +	return div_u64(bdev->bd_inode->i_size,
> +		       bdev_logical_block_size(bdev)) - 1ULL;
>  }
>  
>  static inline int
> @@ -188,6 +192,7 @@ static size_t
>  read_lba(struct block_device *bdev, u64 lba, u8 * buffer, size_t count)
>  {
>  	size_t totalreadcount = 0;
> +	sector_t n = lba * (bdev_logical_block_size(bdev) / 512);
>  
>  	if (!bdev || !buffer || lba > last_lba(bdev))
>                  return 0;
> @@ -195,7 +200,7 @@ read_lba(struct block_device *bdev, u64 lba, u8 * buffer, size_t count)
>  	while (count) {
>  		int copied = 512;
>  		Sector sect;
> -		unsigned char *data = read_dev_sector(bdev, lba++, &sect);
> +		unsigned char *data = read_dev_sector(bdev, n++, &sect);
>  		if (!data)
>  			break;
>  		if (copied > count)
> @@ -601,6 +606,7 @@ efi_partition(struct parsed_partitions *state, struct block_device *bdev)
>  	gpt_header *gpt = NULL;
>  	gpt_entry *ptes = NULL;
>  	u32 i;
> +	unsigned ssz = bdev_logical_block_size(bdev) / 512;
>  
>  	if (!find_valid_gpt(bdev, &gpt, &ptes) || !gpt || !ptes) {
>  		kfree(gpt);
> @@ -611,13 +617,14 @@ efi_partition(struct parsed_partitions *state, struct block_device *bdev)
>  	pr_debug("GUID Partition Table is valid!  Yea!\n");
>  
>  	for (i = 0; i < le32_to_cpu(gpt->num_partition_entries) && i < state->limit-1; i++) {
> +		u64 start = le64_to_cpu(ptes[i].starting_lba);
> +		u64 size = le64_to_cpu(ptes[i].ending_lba) -
> +			   le64_to_cpu(ptes[i].starting_lba) + 1ULL;
> +
>  		if (!is_pte_valid(&ptes[i], last_lba(bdev)))
>  			continue;
>  
> -		put_partition(state, i+1, le64_to_cpu(ptes[i].starting_lba),
> -				 (le64_to_cpu(ptes[i].ending_lba) -
> -                                  le64_to_cpu(ptes[i].starting_lba) +
> -				  1ULL));
> +		put_partition(state, i+1, start * ssz, size * ssz);
>  
>  		/* If this is a RAID volume, tell md */
>  		if (!efi_guidcmp(ptes[i].partition_type_guid,
> -- 
> 1.6.5.1
> 
> 


---
~Randy
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