From: Catalin Marinas <catalin.marinas@arm.com>
Date: Tue, 22 Aug 2017 15:39:00 +0100
Subject: arm64: kaslr: Adjust the offset to avoid Image across alignment
boundary
Git-commit: a067d94d37ed590fd17684d18c3edf52110d305a
Patch-mainline: v4.13-rc7
References: fate#325844
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 <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>
Signed-off-by: Matthias Brugger <mbrugger@suse.com>
---
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))
/*
--
2.19.0