arm64: kaslr: randomize the linear region

[firefly-linux-kernel-4.4.55.git] / arch / arm64 / mm / init.c

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 2c7a3c2868e463cdb0bbbf2e24216ebeba76eec3..58a6d3f7525c5cb9808db3fd5223dbf2b60bed6a 100644 (file)
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -196,6 +196,23 @@ void __init arm64_memblock_init(void)
                memblock_add(__pa(_text), (u64)(_end - _text));
        }
 
+       if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
+               extern u16 memstart_offset_seed;
+               u64 range = linear_region_size -
+                           (memblock_end_of_DRAM() - memblock_start_of_DRAM());
+
+               /*
+                * If the size of the linear region exceeds, by a sufficient
+                * margin, the size of the region that the available physical
+                * memory spans, randomize the linear region as well.
+                */
+               if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
+                       range = range / ARM64_MEMSTART_ALIGN + 1;
+                       memstart_addr -= ARM64_MEMSTART_ALIGN *
+                                        ((range * memstart_offset_seed) >> 16);
+               }
+       }
+
        /*
         * Register the kernel text, kernel data, initrd, and initial
         * pagetables with memblock.
@@ -365,12 +382,13 @@ void __init mem_init(void)
 #ifdef CONFIG_SPARSEMEM_VMEMMAP
                  MLG(VMEMMAP_START,
                      VMEMMAP_START + VMEMMAP_SIZE),
-                 MLM((unsigned long)virt_to_page(PAGE_OFFSET),
+                 MLM((unsigned long)phys_to_page(memblock_start_of_DRAM()),
                      (unsigned long)virt_to_page(high_memory)),
 #endif
                  MLK(FIXADDR_START, FIXADDR_TOP),
                  MLM(PCI_IO_START, PCI_IO_END),
-                 MLM(PAGE_OFFSET, (unsigned long)high_memory));
+                 MLM(__phys_to_virt(memblock_start_of_DRAM()),
+                     (unsigned long)high_memory));
 
 #undef MLK
 #undef MLM