diff options
| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2016-02-22 18:46:04 +0100 |
|---|---|---|
| committer | Jeff Vander Stoep <jeffv@google.com> | 2016-09-22 13:38:22 -0700 |
| commit | b4fd0619fedde9b2849e844db1bde3929c336a82 (patch) | |
| tree | 9171d28a74ccaf6d6d83c2ba44f9a289cfc5833b /arch/arm64/include | |
| parent | 477376b452f0d5fc564dfe2d0fc0fe8156051bb1 (diff) | |
UPSTREAM: arm64: mm: use bit ops rather than arithmetic in pa/va translations
Since PAGE_OFFSET is chosen such that it cuts the kernel VA space right
in half, and since the size of the kernel VA space itself is always a
power of 2, we can treat PAGE_OFFSET as a bitmask and replace the
additions/subtractions with 'or' and 'and-not' operations.
For the comparison against PAGE_OFFSET, a mov/cmp/branch sequence ends
up getting replaced with a single tbz instruction. For the additions and
subtractions, we save a mov instruction since the mask is folded into the
instruction's immediate field.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Bug: 30369029
Patchset: kaslr-arm64-4.4
(cherry picked from commit 8439e62a15614e8fcd43835d57b7245cd9870dc5)
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Change-Id: I1ea4ef654dd7b7693f8713dab28ca0739b8a2c62
Diffstat (limited to 'arch/arm64/include')
| -rw-r--r-- | arch/arm64/include/asm/memory.h | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index 460d09bf9442..eb798156cf56 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -88,10 +88,10 @@ */ #define __virt_to_phys(x) ({ \ phys_addr_t __x = (phys_addr_t)(x); \ - __x >= PAGE_OFFSET ? (__x - PAGE_OFFSET + PHYS_OFFSET) : \ - (__x - kimage_voffset); }) + __x & BIT(VA_BITS - 1) ? (__x & ~PAGE_OFFSET) + PHYS_OFFSET : \ + (__x - kimage_voffset); }) -#define __phys_to_virt(x) ((unsigned long)((x) - PHYS_OFFSET + PAGE_OFFSET)) +#define __phys_to_virt(x) ((unsigned long)((x) - PHYS_OFFSET) | PAGE_OFFSET) #define __phys_to_kimg(x) ((unsigned long)((x) + kimage_voffset)) /* @@ -132,6 +132,7 @@ #ifndef __ASSEMBLY__ +#include <linux/bitops.h> #include <linux/mmdebug.h> extern phys_addr_t memstart_addr; |