arm64: Avoid aligning normal memory pointers in __memcpy_{to,from}io

__memcpy_{to,from}io fall back to byte-at-a-time copying if both the
source and destination pointers are not 8-byte aligned. Since one of the
pointers always points at normal memory, this is unnecessary and
detrimental to performance, so only do byte copying until we hit an 8-byte
boundary for the device pointer.

This change was motivated by performance issues in the pstore driver.
On a test platform, measuring probe time for pstore, console buffer
size of 1/4MB and pmsg of 1/2MB, was in the 90-107ms region. Change
managed to reduce it to 10-25ms, an improvement in boot time.

Cc: Kees Cook <[email protected]>
Cc: Anton Vorontsov <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Anton Vorontsov <[email protected]>
Cc: Robin Murphy <[email protected]>
Signed-off-by: Mark Salyzyn <[email protected]>
Signed-off-by: Will Deacon <[email protected]>

0 files changed, 0 insertions, 0 deletions