diff options
| author | Stuart Menefy <stuart.menefy@st.com> | 2009-10-27 15:14:06 +0000 |
|---|---|---|
| committer | Paul Mundt <lethal@linux-sh.org> | 2009-11-24 17:13:35 +0900 |
| commit | 39ac11c1607f1d566e7cf885acd403fa4f07f8a2 (patch) | |
| tree | a47e6bd8526742f9dfdc177253654e2cac5b829f /arch/sh/include | |
| parent | 49fb2cd2571e0134e5a12c5abab227696e4940c7 (diff) | |
sh: Improve performance of SH4 versions of copy/clear_user_highpage
The previous implementation of clear_user_highpage and copy_user_highpage
checked to see if there was a D-cache aliasing issue between the user
and kernel mappings of a page, but if there was they always did a
flush with writeback on the dirtied kernel alias.
However as we now have the ability to map a page into kernel space
with the same cache colour as the user mapping, there is no need to
write back this data.
Currently we also invalidate the kernel alias as a precaution, however
I'm not sure if this is actually required.
Also correct the definition of FIX_CMAP_END so that the mappings created
by kmap_coherent() are actually at the correct colour.
Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Diffstat (limited to 'arch/sh/include')
| -rw-r--r-- | arch/sh/include/asm/fixmap.h | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/sh/include/asm/fixmap.h b/arch/sh/include/asm/fixmap.h index 76c5a3099cb..5ac1e40a511 100644 --- a/arch/sh/include/asm/fixmap.h +++ b/arch/sh/include/asm/fixmap.h @@ -46,9 +46,15 @@ * fix-mapped? */ enum fixed_addresses { + /* + * The FIX_CMAP entries are used by kmap_coherent() to get virtual + * addresses which are of a known color, and so their values are + * important. __fix_to_virt(FIX_CMAP_END - n) must give an address + * which is the same color as a page (n<<PAGE_SHIFT). + */ #define FIX_N_COLOURS 8 FIX_CMAP_BEGIN, - FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS), + FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS) - 1, FIX_UNCACHED, #ifdef CONFIG_HIGHMEM FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */ |