Commit 8d13c5ee authored Dec 24, 2018 by Yueyi Li Committed by Patrick Daly Mar 27, 2019

arm64: kaslr: Reserve size of ARM64_MEMSTART_ALIGN in linear region



When KASLR is enabled (CONFIG_RANDOMIZE_BASE=y), the top 4K of kernel
virtual address space may be mapped to physical addresses despite being
reserved for ERR_PTR values.

Fix the randomization of the linear region so that we avoid mapping the
last page of the virtual address space.

Change-Id: I3035dbe8e64b2a31f5d56b7dc29366958adda6ce
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: liyueyi <liyueyi@live.com>
[will: rewrote commit message; merged in suggestion from Ard]
Signed-off-by: Will Deacon <will.deacon@arm.com>
Git-commit: c8a43c18a97845e7f94ed7d181c11f41964976a2
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>

parent 1c2977d1

arch/arm64/mm/init.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -542,7 +542,7 @@ void __init arm64_memblock_init(void)
		* memory spans, randomize the linear region as well.
		*/
		if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
		range = range / ARM64_MEMSTART_ALIGN + 1;
		range /= ARM64_MEMSTART_ALIGN;
		memstart_addr -= ARM64_MEMSTART_ALIGN *
		((range * memstart_offset_seed) >> 16);
		}