Merge tag 'for-linus-20170825' of git://git.infradead.org/linux-mtd

[mirror_ubuntu-artful-kernel.git] / arch / arm64 / kernel / kaslr.c

diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
index a9710efb8c017a735f9aa6518463d11b8d6264c9..47080c49cc7e77a3df120f061f7b10f90a8c2ec5 100644 (file)
--- a/arch/arm64/kernel/kaslr.c
+++ b/arch/arm64/kernel/kaslr.c
@@ -75,7 +75,7 @@ extern void *__init __fixmap_remap_fdt(phys_addr_t dt_phys, int *size,
  * containing function pointers) to be reinitialized, and zero-initialized
  * .bss variables will be reset to 0.
  */
-u64 __init kaslr_early_init(u64 dt_phys, u64 modulo_offset)
+u64 __init kaslr_early_init(u64 dt_phys)
 {
        void *fdt;
        u64 seed, offset, mask, module_range;
@@ -131,15 +131,17 @@ u64 __init kaslr_early_init(u64 dt_phys, u64 modulo_offset)
        /*
         * 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
+        *       account, given that the physical placement is controlled by
+        *       the loader, and will not change as a result of the virtual
+        *       mapping we choose.
         */
-       if ((((u64)_text + offset + modulo_offset) >> SWAPPER_TABLE_SHIFT) !=
-           (((u64)_end + offset + modulo_offset) >> SWAPPER_TABLE_SHIFT)) {
-               u64 kimg_sz = _end - _text;
-               offset = (offset + round_up(kimg_sz, SWAPPER_BLOCK_SIZE))
-                               & mask;
-       }
+       if ((((u64)_text + offset) >> SWAPPER_TABLE_SHIFT) !=
+           (((u64)_end + offset) >> SWAPPER_TABLE_SHIFT))
+               offset = round_down(offset, 1 << SWAPPER_TABLE_SHIFT);
 
        if (IS_ENABLED(CONFIG_KASAN))
                /*