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authorCatalin Marinas <catalin.marinas@arm.com>2017-08-22 15:39:00 +0100
committerWill Deacon <will.deacon@arm.com>2017-08-22 18:15:42 +0100
commita067d94d37ed590fd17684d18c3edf52110d305a (patch)
treea9a77b734e1d41672784140020add86574b48e08 /arch/arm64/kernel
parentarm64: kaslr: ignore modulo offset when validating virtual displacement (diff)
downloadlinux-dev-a067d94d37ed590fd17684d18c3edf52110d305a.tar.xz
linux-dev-a067d94d37ed590fd17684d18c3edf52110d305a.zip
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 <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>
Diffstat (limited to 'arch/arm64/kernel')
-rw-r--r--arch/arm64/kernel/kaslr.c10
1 files 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))
/*