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author | Steve Capper <steve.capper@arm.com> | 2018-12-06 22:50:37 +0000 |
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committer | Will Deacon <will.deacon@arm.com> | 2018-12-10 18:42:17 +0000 |
commit | 363524d2b12270d86677e1154ecc1c5061f43219 (patch) | |
tree | 1b4653ee1c9509e7233e8d3a75a2f8cb8c66f62b /arch/arm64/mm | |
parent | f6795053dac8d4d2f90d4a98842dd6d2ccd544ad (diff) | |
download | linux-stable-363524d2b12270d86677e1154ecc1c5061f43219.tar.gz linux-stable-363524d2b12270d86677e1154ecc1c5061f43219.tar.bz2 linux-stable-363524d2b12270d86677e1154ecc1c5061f43219.zip |
arm64: mm: Introduce DEFAULT_MAP_WINDOW
We wish to introduce a 52-bit virtual address space for userspace but
maintain compatibility with software that assumes the maximum VA space
size is 48 bit.
In order to achieve this, on 52-bit VA systems, we make mmap behave as
if it were running on a 48-bit VA system (unless userspace explicitly
requests a VA where addr[51:48] != 0).
On a system running a 52-bit userspace we need TASK_SIZE to represent
the 52-bit limit as it is used in various places to distinguish between
kernelspace and userspace addresses.
Thus we need a new limit for mmap, stack, ELF loader and EFI (which uses
TTBR0) to represent the non-extended VA space.
This patch introduces DEFAULT_MAP_WINDOW and DEFAULT_MAP_WINDOW_64 and
switches the appropriate logic to use that instead of TASK_SIZE.
Signed-off-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/mm')
-rw-r--r-- | arch/arm64/mm/init.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 2983e0fc1786..6cde00554e9b 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -609,7 +609,7 @@ void __init mem_init(void) * detected at build time already. */ #ifdef CONFIG_COMPAT - BUILD_BUG_ON(TASK_SIZE_32 > TASK_SIZE_64); + BUILD_BUG_ON(TASK_SIZE_32 > DEFAULT_MAP_WINDOW_64); #endif #ifdef CONFIG_SPARSEMEM_VMEMMAP |