diff options
| author | Steve Capper <steve.capper@arm.com> | 2019-08-07 16:55:17 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2019-08-09 11:17:16 +0100 |
| commit | 90ec95cda91a021d82351c976896a63aa364ebf1 (patch) | |
| tree | 6f5295463a65f0cda5e79bd47998ab10df11c0f6 /arch/arm64/kernel | |
| parent | 99426e5e8c9f11b9de65e7c1200868e8a9ceaa47 (diff) | |
arm64: mm: Introduce VA_BITS_MIN
In order to support 52-bit kernel addresses detectable at boot time, the
kernel needs to know the most conservative VA_BITS possible should it
need to fall back to this quantity due to lack of hardware support.
A new compile time constant VA_BITS_MIN is introduced in this patch and
it is employed in the KASAN end address, KASLR, and EFI stub.
For Arm, if 52-bit VA support is unavailable the fallback is to 48-bits.
In other words: VA_BITS_MIN = min (48, VA_BITS)
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Steve Capper <steve.capper@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel')
| -rw-r--r-- | arch/arm64/kernel/head.S | 2 | ||||
| -rw-r--r-- | arch/arm64/kernel/kaslr.c | 6 |
2 files changed, 4 insertions, 4 deletions
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 2cdacd1c141b..ac58c69993ec 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -314,7 +314,7 @@ __create_page_tables: mov x5, #52 cbnz x6, 1f #endif - mov x5, #VA_BITS + mov x5, #VA_BITS_MIN 1: adr_l x6, vabits_user str x5, [x6] diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c index 708051655ad9..5a59f7567f9c 100644 --- a/arch/arm64/kernel/kaslr.c +++ b/arch/arm64/kernel/kaslr.c @@ -116,15 +116,15 @@ u64 __init kaslr_early_init(u64 dt_phys) /* * OK, so we are proceeding with KASLR enabled. Calculate a suitable * kernel image offset from the seed. Let's place the kernel in the - * middle half of the VMALLOC area (VA_BITS - 2), and stay clear of + * middle half of the VMALLOC area (VA_BITS_MIN - 2), and stay clear of * the lower and upper quarters to avoid colliding with other * allocations. * Even if we could randomize at page granularity for 16k and 64k pages, * let's always round to 2 MB so we don't interfere with the ability to * map using contiguous PTEs */ - mask = ((1UL << (VA_BITS - 2)) - 1) & ~(SZ_2M - 1); - offset = BIT(VA_BITS - 3) + (seed & mask); + mask = ((1UL << (VA_BITS_MIN - 2)) - 1) & ~(SZ_2M - 1); + offset = BIT(VA_BITS_MIN - 3) + (seed & mask); /* use the top 16 bits to randomize the linear region */ memstart_offset_seed = seed >> 48; |