From a067d94d37ed590fd17684d18c3edf52110d305a Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Tue, 22 Aug 2017 15:39:00 +0100 Subject: [PATCH] arm64: kaslr: Adjust the offset to avoid Image across alignment boundary With 16KB pages and a kernel Image larger than 16MB, the current kaslr_early_init() logic for avoiding mappings across swapper table boundaries fails since increasing the offset by kimg_sz just moves the problem to the next boundary. This patch rounds the offset down to (1 << SWAPPER_TABLE_SHIFT) if the Image crosses a PMD_SIZE boundary. Fixes: afd0e5a87670 ("arm64: kaslr: Fix up the kernel image alignment") Cc: Ard Biesheuvel Cc: Mark Rutland Cc: Will Deacon Cc: Neeraj Upadhyay Signed-off-by: Catalin Marinas Signed-off-by: Will Deacon --- arch/arm64/kernel/kaslr.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c index 1d95c204186b..47080c49cc7e 100644 --- a/arch/arm64/kernel/kaslr.c +++ b/arch/arm64/kernel/kaslr.c @@ -131,8 +131,7 @@ u64 __init kaslr_early_init(u64 dt_phys) /* * The kernel Image should not extend across a 1GB/32MB/512MB alignment * boundary (for 4KB/16KB/64KB granule kernels, respectively). If this - * happens, increase the KASLR offset by the size of the kernel image - * rounded up by SWAPPER_BLOCK_SIZE. + * happens, round down the KASLR offset by (1 << SWAPPER_TABLE_SHIFT). * * NOTE: The references to _text and _end below will already take the * modulo offset (the physical displacement modulo 2 MB) into @@ -141,11 +140,8 @@ u64 __init kaslr_early_init(u64 dt_phys) * mapping we choose. */ if ((((u64)_text + offset) >> SWAPPER_TABLE_SHIFT) != - (((u64)_end + offset) >> SWAPPER_TABLE_SHIFT)) { - u64 kimg_sz = _end - _text; - offset = (offset + round_up(kimg_sz, SWAPPER_BLOCK_SIZE)) - & mask; - } + (((u64)_end + offset) >> SWAPPER_TABLE_SHIFT)) + offset = round_down(offset, 1 << SWAPPER_TABLE_SHIFT); if (IS_ENABLED(CONFIG_KASAN)) /* -- 2.20.1