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Commit a067d94d authored by Catalin Marinas's avatar Catalin Marinas Committed by Will Deacon
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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: afd0e5a8 ("arm64: kaslr: Fix up the kernel image alignment")
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 4a23e56a

arch/arm64/kernel/kaslr.c

+3 −7
Original line number Diff line number Diff line
@@ -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))

		/*