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Commit 020d044f authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Catalin Marinas
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arm64: mm: treat memstart_addr as a signed quantity 



Commit c031a421 ("arm64: kaslr: randomize the linear region")
implements randomization of the linear region, by subtracting a random
multiple of PUD_SIZE from memstart_addr. This causes the virtual mapping
of system RAM to move upwards in the linear region, and at the same time
causes memstart_addr to assume a value which may be negative if the offset
of system RAM in the physical space is smaller than its offset relative to
PAGE_OFFSET in the virtual space.

Since memstart_addr is effectively an offset now, redefine its type as s64
so that expressions involving shifting or division preserve its sign.

Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent a6e1f727

arch/arm64/include/asm/memory.h

+1 −1
Original line number Diff line number Diff line
@@ -135,7 +135,7 @@ 
#include <linux/bitops.h>

#include <linux/mmdebug.h>



extern phys_addr_t		memstart_addr;

extern s64			memstart_addr;

/* PHYS_OFFSET - the physical address of the start of memory. */

#define PHYS_OFFSET		({ VM_BUG_ON(memstart_addr & 1); memstart_addr; })

arch/arm64/mm/init.c

+2 −2
Original line number Diff line number Diff line
@@ -54,7 +54,7 @@ 
 * executes, which assigns it its actual value. So use a default value

 * that cannot be mistaken for a real physical address.

 */

phys_addr_t memstart_addr __read_mostly = ~0ULL;

s64 memstart_addr __read_mostly = -1;

phys_addr_t arm64_dma_phys_limit __read_mostly;



#ifdef CONFIG_BLK_DEV_INITRD
@@ -181,7 +181,7 @@ void __init arm64_memblock_init(void) 
	 * linear mapping. Take care not to clip the kernel which may be

	 * high in memory.

	 */

	memblock_remove(max(memstart_addr + linear_region_size, __pa(_end)),

	memblock_remove(max_t(u64, memstart_addr + linear_region_size, __pa(_end)),

			ULLONG_MAX);

	if (memblock_end_of_DRAM() > linear_region_size)

		memblock_remove(0, memblock_end_of_DRAM() - linear_region_size);