@@ -792,6 +792,10 @@ config ARM64_VA_BITS
default 47 if ARM64_VA_BITS_47
default 48 if ARM64_VA_BITS_48 || ARM64_USER_VA_BITS_52
+config ARM64_VA_BITS_MIN
+ int
+ default ARM64_VA_BITS
+
choice
prompt "Physical address space size"
default ARM64_PA_BITS_48
@@ -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__)
@@ -63,6 +63,9 @@
#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)
+#define VA_BITS_MIN (CONFIG_ARM64_VA_BITS_MIN)
+#define _VA_START(va) (UL(0xffffffffffffffff) - \
+ (UL(1) << ((va) - 1)) + 1)
#define KERNEL_START _text
#define KERNEL_END _end
@@ -89,7 +92,7 @@
#endif
#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)
@@ -53,7 +53,7 @@
* 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
@@ -325,7 +325,7 @@ __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]
@@ -119,15 +119,15 @@ 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;
@@ -158,7 +158,8 @@ static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
/* The early shadow maps everything to a single page of zeroes */
asmlinkage void __init kasan_early_init(void)
{
- 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);
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) Signed-off-by: Steve Capper <steve.capper@arm.com> --- arch/arm64/Kconfig | 4 ++++ arch/arm64/include/asm/efi.h | 4 ++-- arch/arm64/include/asm/memory.h | 5 ++++- 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 ++- 7 files changed, 17 insertions(+), 9 deletions(-)