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authorYueyi Li <liyueyi@live.com>2018-12-24 07:40:07 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-04-17 08:36:44 +0200
commitda6c4933cd5795e115124e50f93bc5426dec19a0 (patch)
tree0d0722e543852ec74350a77dc41107a5d3989969
parent91f69a3c910f97215e8f49207497084c472d1fa3 (diff)
arm64: kaslr: Reserve size of ARM64_MEMSTART_ALIGN in linear region
[ Upstream commit c8a43c18a97845e7f94ed7d181c11f41964976a2 ] 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. 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> Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>
-rw-r--r--arch/arm64/mm/init.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index fa6b2fad7a3d..5d3df68272f5 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -272,7 +272,7 @@ 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);
}