diff options
author | Will Deacon <will.deacon@arm.com> | 2012-08-10 12:51:19 -0400 |
---|---|---|
committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2012-08-11 04:15:59 -0400 |
commit | f5f2025ef3e2cdb593707cbf87378761f17befbe (patch) | |
tree | 92e3e13ae25f950781294c112a4a03176e39fd10 | |
parent | 47f1204329237a0f8655f5a9f14a38ac81946ca1 (diff) |
ARM: 7488/1: mm: use 5 bits for swapfile type encoding
Page migration encodes the pfn in the offset field of a swp_entry_t.
For LPAE, we support physical addresses of up to 36 bits (due to
sparsemem limitations with the size of page flags), requiring 24 bits
to represent a pfn. A further 3 bits are used to encode a swp_entry into
a pte, leaving 5 bits for the type field. Furthermore, the core code
defines MAX_SWAPFILES_SHIFT as 5, so the additional type bit does not
get used.
This patch reduces the width of the type field to 5 bits, allowing us
to create up to 31 swapfiles of 64GB each.
Cc: <stable@vger.kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r-- | arch/arm/include/asm/pgtable.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h index d88f9f049e95..41dc31f834c3 100644 --- a/arch/arm/include/asm/pgtable.h +++ b/arch/arm/include/asm/pgtable.h | |||
@@ -253,13 +253,13 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) | |||
253 | * | 253 | * |
254 | * 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 | 254 | * 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 |
255 | * 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 | 255 | * 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 |
256 | * <--------------- offset --------------------> <- type --> 0 0 0 | 256 | * <--------------- offset ----------------------> < type -> 0 0 0 |
257 | * | 257 | * |
258 | * This gives us up to 63 swap files and 32GB per swap file. Note that | 258 | * This gives us up to 31 swap files and 64GB per swap file. Note that |
259 | * the offset field is always non-zero. | 259 | * the offset field is always non-zero. |
260 | */ | 260 | */ |
261 | #define __SWP_TYPE_SHIFT 3 | 261 | #define __SWP_TYPE_SHIFT 3 |
262 | #define __SWP_TYPE_BITS 6 | 262 | #define __SWP_TYPE_BITS 5 |
263 | #define __SWP_TYPE_MASK ((1 << __SWP_TYPE_BITS) - 1) | 263 | #define __SWP_TYPE_MASK ((1 << __SWP_TYPE_BITS) - 1) |
264 | #define __SWP_OFFSET_SHIFT (__SWP_TYPE_BITS + __SWP_TYPE_SHIFT) | 264 | #define __SWP_OFFSET_SHIFT (__SWP_TYPE_BITS + __SWP_TYPE_SHIFT) |
265 | 265 | ||