| Message ID | 20160622125905.1269359-1-arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
diff --git a/block/partitions/efi.c b/block/partitions/efi.c index bcd86e5cd546..7d83cf069574 100644 --- a/block/partitions/efi.c +++ b/block/partitions/efi.c @@ -147,10 +147,13 @@ efi_crc32(const void *buf, unsigned long len) */ static u64 last_lba(struct block_device *bdev) { + unsigned int blocksize; + if (!bdev || !bdev->bd_inode) return 0; - return div_u64(bdev->bd_inode->i_size, - bdev_logical_block_size(bdev)) - 1ULL; + + blocksize = bdev_logical_block_size(bdev); + return (bdev->bd_inode->i_size >> ilog2(blocksize)) - 1ULL; } static inline int pmbr_part_valid(gpt_mbr_record *part)
Enabling CONFIG_UBSAN_SANITIZE_ALL on ARM caused a link error: last_lba.part.0': :(.text+0xc3440): undefined reference to `____ilog2_NaN' :(.text+0xc3538): undefined reference to `__aeabi_uldivmod' :(.text+0xc38e8): undefined reference to `__aeabi_uldivmod' This is caused by gcc not behaving in the expected ways with __builtin_constant_p(), but it also points to somewhat inefficient code: As we know that the block size is a power-of-two value, we can turn the expensive 64-bit division into a simpler variable bit shift. Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- block/partitions/efi.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)