diff options
| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2015-03-19 16:42:27 +0000 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2015-03-23 11:35:29 +0000 |
| commit | dd006da21646f1c86f0242eb8f527d093303127a (patch) | |
| tree | b67ea3943e04f7d6b643b0f38c4cba7f3db42ace /arch/arm64/include/asm/page.h | |
| parent | 6232cfd0fa01fe392df0b18a3a06628f130b83b2 (diff) | |
| download | linux-dd006da21646f1c86f0242eb8f527d093303127a.tar.bz2 | |
arm64: mm: increase VA range of identity map
The page size and the number of translation levels, and hence the supported
virtual address range, are build-time configurables on arm64 whose optimal
values are use case dependent. However, in the current implementation, if
the system's RAM is located at a very high offset, the virtual address range
needs to reflect that merely because the identity mapping, which is only used
to enable or disable the MMU, requires the extended virtual range to map the
physical memory at an equal virtual offset.
This patch relaxes that requirement, by increasing the number of translation
levels for the identity mapping only, and only when actually needed, i.e.,
when system RAM's offset is found to be out of reach at runtime.
Tested-by: Laura Abbott <lauraa@codeaurora.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/include/asm/page.h')
| -rw-r--r-- | arch/arm64/include/asm/page.h | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h index 22b16232bd60..3d02b1869eb8 100644 --- a/arch/arm64/include/asm/page.h +++ b/arch/arm64/include/asm/page.h @@ -33,7 +33,9 @@ * image. Both require pgd, pud (4 levels only) and pmd tables to (section) * map the kernel. With the 64K page configuration, swapper and idmap need to * map to pte level. The swapper also maps the FDT (see __create_page_tables - * for more information). + * for more information). Note that the number of ID map translation levels + * could be increased on the fly if system RAM is out of reach for the default + * VA range, so 3 pages are reserved in all cases. */ #ifdef CONFIG_ARM64_64K_PAGES #define SWAPPER_PGTABLE_LEVELS (CONFIG_ARM64_PGTABLE_LEVELS) @@ -42,7 +44,7 @@ #endif #define SWAPPER_DIR_SIZE (SWAPPER_PGTABLE_LEVELS * PAGE_SIZE) -#define IDMAP_DIR_SIZE (SWAPPER_DIR_SIZE) +#define IDMAP_DIR_SIZE (3 * PAGE_SIZE) #ifndef __ASSEMBLY__ |