From 90ec95cda91a021d82351c976896a63aa364ebf1 Mon Sep 17 00:00:00 2001 From: Steve Capper Date: Wed, 7 Aug 2019 16:55:17 +0100 Subject: [PATCH] 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 Signed-off-by: Steve Capper Signed-off-by: Will Deacon --- arch/arm64/include/asm/efi.h | 4 ++-- arch/arm64/include/asm/memory.h | 9 ++++++++- arch/arm64/include/asm/processor.h | 2 +- arch/arm64/kernel/head.S | 2 +- arch/arm64/kernel/kaslr.c | 6 +++--- arch/arm64/mm/kasan_init.c | 3 ++- 6 files changed, 17 insertions(+), 9 deletions(-) diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h index 76a144702586..b54d3a86c444 100644 --- a/arch/arm64/include/asm/efi.h +++ b/arch/arm64/include/asm/efi.h @@ -79,7 +79,7 @@ static inline unsigned long efi_get_max_fdt_addr(unsigned long dram_base) /* * On arm64, we have to ensure that the initrd ends up in the linear region, - * which is a 1 GB aligned region of size '1UL << (VA_BITS - 1)' that is + * which is a 1 GB aligned region of size '1UL << (VA_BITS_MIN - 1)' that is * guaranteed to cover the kernel Image. * * Since the EFI stub is part of the kernel Image, we can relax the @@ -90,7 +90,7 @@ static inline unsigned long efi_get_max_fdt_addr(unsigned long dram_base) static inline unsigned long efi_get_max_initrd_addr(unsigned long dram_base, unsigned long image_addr) { - return (image_addr & ~(SZ_1G - 1UL)) + (1UL << (VA_BITS - 1)); + return (image_addr & ~(SZ_1G - 1UL)) + (1UL << (VA_BITS_MIN - 1)); } #define efi_call_early(f, ...) sys_table_arg->boottime->f(__VA_ARGS__) diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index 968659c90f5c..79e75e45d560 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -52,6 +52,13 @@ #define PCI_IO_END (VMEMMAP_START - SZ_2M) #define PCI_IO_START (PCI_IO_END - PCI_IO_SIZE) #define FIXADDR_TOP (PCI_IO_START - SZ_2M) +#if VA_BITS > 48 +#define VA_BITS_MIN (48) +#else +#define VA_BITS_MIN (VA_BITS) +#endif +#define _VA_START(va) (UL(0xffffffffffffffff) - \ + (UL(1) << ((va) - 1)) + 1) #define KERNEL_START _text #define KERNEL_END _end @@ -74,7 +81,7 @@ #define KASAN_THREAD_SHIFT 1 #else #define KASAN_THREAD_SHIFT 0 -#define KASAN_SHADOW_END (VA_START) +#define KASAN_SHADOW_END (_VA_START(VA_BITS_MIN)) #endif #define MIN_THREAD_SHIFT (14 + KASAN_THREAD_SHIFT) diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index 844e2964b0f5..0e1f2770192a 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -42,7 +42,7 @@ * TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area. */ -#define DEFAULT_MAP_WINDOW_64 (UL(1) << VA_BITS) +#define DEFAULT_MAP_WINDOW_64 (UL(1) << VA_BITS_MIN) #define TASK_SIZE_64 (UL(1) << vabits_user) #ifdef CONFIG_COMPAT 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; diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c index 05edfe9b02e4..725222271474 100644 --- a/arch/arm64/mm/kasan_init.c +++ b/arch/arm64/mm/kasan_init.c @@ -156,7 +156,8 @@ asmlinkage void __init kasan_early_init(void) { BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT))); - BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE)); + BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS), PGDIR_SIZE)); + BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS_MIN), PGDIR_SIZE)); BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, true);