sh: Handle fixmap TLB eviction more coherently.
authorPaul Mundt <lethal@linux-sh.org>
Mon, 10 Nov 2008 11:00:45 +0000 (20:00 +0900)
committerPaul Mundt <lethal@linux-sh.org>
Mon, 10 Nov 2008 11:00:45 +0000 (20:00 +0900)
commitacca4f4d9bd657e8bc7e1665ba5077465138f133
tree39b107c67d9dc59e6064e528457ca97ba4396ba2
parentf7160c7573615ec82c691e294cf80d920b5d588d
sh: Handle fixmap TLB eviction more coherently.

There was a race in the kmap_coherent() implementation. While we
guarded against preemption, there was nothing preventing eviction of
the pre-faulted fixmap entry from the UTLB. Under certain workloads
this would result in the fixmap entries used for cache colouring being
evicted from the UTLB in the midst of a copy_page().

In addition to pre-faulting, we also make sure to preserve the PTEs
in the kernel page table and introduce a cached PTE for kmap_coherent()
usage. This follows a similar change on MIPS ("[MIPS] Fix aliasing bug
in copy_to_user_page / copy_from_user_page").

Reported-by: Hideo Saito <saito@densan.co.jp>
Reported-by: CHIKAMA Masaki <masaki.chikama@gmail.com>
Tested-by: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
arch/sh/include/asm/pgtable.h
arch/sh/mm/init.c
arch/sh/mm/pg-sh4.c