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| author |   John David Anglin <dave.anglin@bell.net> | 2013-02-03 22:59:09 +0000 |
|---|---|---|
| committer |   Helge Deller <deller@gmx.de> | 2013-02-20 22:49:19 +0100 |
| commit | 7633453978c54874849c5f40487ac9e14d43fc12 (patch) | |
| tree | 552bc9a01785d2bcdca5cb283b6b2b3af5e3e5b8 /arch/parisc/kernel/parisc_ksyms.c | |
| parent | drivers/parisc/pdc_stable.c: use WARN (diff) | |
| download | linux-dev-7633453978c54874849c5f40487ac9e14d43fc12.tar.xz linux-dev-7633453978c54874849c5f40487ac9e14d43fc12.zip | |
parisc: fixes and cleanups in page cache flushing (1/4)
This is the first patch in a series of 4, with which the page cache flushing of
parisc will gets fixed and enhanced. This even fixes the nasty "minifail" bug
(http://wiki.parisc-linux.org/TestCases?highlight=%28minifail%29) which
prevented parisc to stay an official debian port. Basically the flush in
copy_user_page together with the TLB patch from commit
7139bc1579901b53db7e898789e916ee2fb52d78 is what fixes the minifail bug.
This patch still uses the TMPALIAS approach. The new copy_user_page
implementation calls flush_dcache_page_asm to flush the user dcache page
(crucial for minifail fix) via a kernel TMPALIAS mapping. After that, it just
copies the page using the kernel mapping. It does a final flush if needed.
Generally it is hard to avoid doing some cache flushes using the kernel mapping
(e.g., copy_to_user_page and copy_from_user_page).
This patch depends on a subsequent change to pacache.S implementing
clear_page_asm and copy_page_asm. These are optimized routines to clear and
copy a page. The calls in clear_user_page and copy_user_page could be replaced
by calls to memset and memcpy, respectively. I tested prefetch optimizations
in clear_page_asm and copy_page_asm but didn't see any significant performance
improvement on rp3440. I'm not sure if these are routines are significantly
faster than memset and/or memcpy, but they are there for further performance
evaluation.
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Diffstat (limited to 'arch/parisc/kernel/parisc_ksyms.c')
| -rw-r--r-- | arch/parisc/kernel/parisc_ksyms.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/parisc/kernel/parisc_ksyms.c b/arch/parisc/kernel/parisc_ksyms.c index ceec85de6290..6795dc6c995f 100644 --- a/arch/parisc/kernel/parisc_ksyms.c +++ b/arch/parisc/kernel/parisc_ksyms.c @@ -157,5 +157,6 @@ extern void _mcount(void); EXPORT_SYMBOL(_mcount); #endif -/* from pacache.S -- needed for copy_page */ -EXPORT_SYMBOL(copy_user_page_asm); +/* from pacache.S -- needed for clear/copy_page */ +EXPORT_SYMBOL(clear_page_asm); +EXPORT_SYMBOL(copy_page_asm); |