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Nicolas Pitre 7e5a69e83b ARM: 6007/1: fix highmem with VIPT cache and DMA 
The VIVT cache of a highmem page is always flushed before the page
is unmapped.  This cache flush is explicit through flush_cache_kmaps()
in flush_all_zero_pkmaps(), or through __cpuc_flush_dcache_area() in
kunmap_atomic().  There is also an implicit flush of those highmem pages
that were part of a process that just terminated making those pages free
as the whole VIVT cache has to be flushed on every task switch. Hence
unmapped highmem pages need no cache maintenance in that case.

However unmapped pages may still be cached with a VIPT cache because the
cache is tagged with physical addresses.  There is no need for a whole
cache flush during task switching for that reason, and despite the
explicit cache flushes in flush_all_zero_pkmaps() and kunmap_atomic(),
some highmem pages that were mapped in user space end up still cached
even when they become unmapped.

So, we do have to perform cache maintenance on those unmapped highmem
pages in the context of DMA when using a VIPT cache.  Unfortunately,
it is not possible to perform that cache maintenance using physical
addresses as all the L1 cache maintenance coprocessor functions accept
virtual addresses only.  Therefore we have no choice but to set up a
temporary virtual mapping for that purpose.

And of course the explicit cache flushing when unmapping a highmem page
on a system with a VIPT cache now can go, which should increase
performance.

While at it, because the code in __flush_dcache_page() has to be modified
anyway, let's also make sure the mapped highmem pages are pinned with
kmap_high_get() for the duration of the cache maintenance operation.
Because kunmap() does unmap highmem pages lazily, it was reported by
Gary King <GKing@nvidia.com> that those pages ended up being unmapped
during cache maintenance on SMP causing segmentation faults.

Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-04-14 11:11:27 +01:00
..
boot ARM: 6031/1: fix Thumb-2 decompressor 2010-04-07 21:11:29 +01:00
common include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
configs Merge branch 'omap-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap-2.6 2010-03-18 16:59:30 -07:00
include/asm ARM: 6007/1: fix highmem with VIPT cache and DMA 2010-04-14 11:11:27 +01:00
kernel Merge branch 'master' into export-slabh 2010-04-05 11:37:28 +09:00
lib Merge branch 'master' into export-slabh 2010-04-05 11:37:28 +09:00
mach-aaec2000 include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-at91 ARM: 5975/1: AT91 slow-clock suspend: don't wait when turning PLLs off 2010-04-14 11:08:43 +01:00
mach-bcmring ARM: 6024/1: bcmring: fix missing down on semaphore in dma.c 2010-04-07 21:11:27 +01:00
mach-clps711x
mach-davinci Merge branch 'davinci-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/khilman/linux-davinci 2010-04-07 11:03:06 -07:00
mach-dove Merge branch 'origin' into devel-stable 2010-03-08 20:21:04 +00:00
mach-ebsa110
mach-ep93xx ARM: 6029/1: ep93xx: gpio.c: local functions should be static 2010-04-07 21:11:28 +01:00
mach-footbridge Merge branch 'misc2' into devel 2010-02-25 22:09:41 +00:00
mach-gemini Merge branch 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm 2010-03-01 09:15:15 -08:00
mach-h720x include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-integrator include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-iop13xx include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-iop32x include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-iop33x include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-ixp4xx include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-ixp23xx include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-ixp2000 include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-kirkwood include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-ks8695
mach-l7200
mach-lh7a40x include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-loki Merge branch 'misc2' into devel 2010-02-25 22:09:41 +00:00
mach-mmp [ARM] mmp: fix for variables in uncompress.h being discarded 2010-03-22 12:03:05 +08:00
mach-msm Merge branch 'misc2' into devel 2010-02-25 22:09:41 +00:00
mach-mv78xx0 Merge branch 'origin' into devel-stable 2010-03-08 20:21:04 +00:00
mach-mx1 Merge branch 'origin' into devel-stable 2010-03-08 20:21:04 +00:00
mach-mx2 Merge branch 'origin' into devel-stable 2010-03-08 20:21:04 +00:00
mach-mx3 Merge branch 'for-rmk' of git://git.pengutronix.de/git/imx/linux-2.6 2010-04-08 10:47:05 +01:00
mach-mx5 i.MX51: remove NFC AXI static mapping 2010-03-19 11:18:27 +01:00
mach-mx25 Merge branch 'origin' into devel-stable 2010-03-08 20:21:04 +00:00
mach-mxc91231 Merge branch 'origin' into devel-stable 2010-03-08 20:21:04 +00:00
mach-netx include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-nomadik include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-ns9xxx include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-nuc93x
mach-omap1 include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-omap2 include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-orion5x include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-pnx4008 include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-pxa include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-realview include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-rpc include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-s3c24a0/include/mach Merge branch 'origin' into devel-stable 2010-03-08 20:21:04 +00:00
mach-s3c64xx include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-s3c2400
mach-s3c2410 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2010-03-12 16:04:50 -08:00
mach-s3c2412
mach-s3c2440 ARM: S3C2440: Fix s3c2440 cpufreq compilation post move. 2010-03-15 22:43:12 +00:00
mach-s3c2443 ARM: Merge next-samsung-s3c2443-clock 2010-03-07 22:56:19 +00:00
mach-s5p6440 ARM: SAMSUNG: Fixup commit 4e6d488af3 2010-03-15 23:11:41 +00:00
mach-s5p6442 ARM: SAMSUNG: Fixup commit 4e6d488af3 2010-03-15 23:11:41 +00:00
mach-s5pc100 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2010-03-12 16:04:50 -08:00
mach-s5pv210 Merge branch 'origin' into devel-stable 2010-03-08 20:21:04 +00:00
mach-sa1100 include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-shark
mach-shmobile ARM: mach-shmobile: ap4evb SDHI0 platform data V2 2010-03-15 12:06:47 +09:00
mach-stmp37xx
mach-stmp378x
mach-u300 include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-ux500 Merge branch 'master' into for-linus 2010-03-08 20:24:11 +00:00
mach-versatile include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mach-w90x900 include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mm ARM: 6007/1: fix highmem with VIPT cache and DMA 2010-04-14 11:11:27 +01:00
nwfpe
oprofile
plat-iop
plat-mxc Merge branch 'for-rmk' of git://git.pengutronix.de/git/imx/linux-2.6 2010-04-08 10:47:05 +01:00
plat-nomadik Merge branch 'origin' into devel-stable 2010-03-08 20:21:04 +00:00
plat-omap include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
plat-orion
plat-pxa include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
plat-s3c24xx include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
plat-s5p ARM: S5PV210: Update Kconfig and Makefiles 2010-02-24 22:47:23 +00:00
plat-s5pc1xx
plat-samsung include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
plat-stmp3xxx include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
tools ARM: Update mach-types 2010-03-20 15:37:39 +00:00
vfp ARM: 5997/1: ARM: Correct the VFPv3 detection 2010-03-28 10:40:14 +01:00
Kconfig ARM: Fix sorting of platform group config options and includes 2010-03-15 19:03:06 +00:00
Kconfig-nommu
Kconfig.debug
Makefile Merge branch 'origin' into devel-stable 2010-03-08 20:21:04 +00:00