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arm64: kaslr: Adjust the offset to avoid Image across alignment boundary

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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: afd0e5a876 ("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: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Catalin Marinas 2017-08-22 15:39:00 +01:00 committed by Will Deacon
parent 4a23e56ad6
commit a067d94d37
1 changed files with 3 additions and 7 deletions
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10
arch/arm64/kernel/kaslr.c
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@ -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))
/*