arm64: setup: introduce kaslr_offset()

Introduce kaslr_offset() similar to x86_64 to fix kcov.

[ Updated by Will Deacon ]

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Alexander Popov <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Kefeng Wang <[email protected]>
Cc: AKASHI Takahiro <[email protected]>
Cc: Jon Masters <[email protected]>
Cc: David Daney <[email protected]>
Cc: Ganapatrao Kulkarni <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Nicolai Stange <[email protected]>
Cc: James Morse <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Alexander Popov <[email protected]>
Cc: syzkaller <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Will Deacon <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

arch/arm64/include/asm/memory.h

@@ -165,6 +165,11 @@ extern u64			kimage_vaddr;
 /* the offset between the kernel virtual and physical mappings */
 extern u64			kimage_voffset;
 
+static inline unsigned long kaslr_offset(void)
+{
+	return kimage_vaddr - KIMAGE_VADDR;
+}
+
 /*
  * Allow all memory at the discovery stage. We will clip it later.
  */

arch/arm64/kernel/setup.c

@@ -338,11 +338,11 @@ subsys_initcall(topology_init);
 static int dump_kernel_offset(struct notifier_block *self, unsigned long v,
 			      void *p)
 {
-	u64 const kaslr_offset = kimage_vaddr - KIMAGE_VADDR;
+	const unsigned long offset = kaslr_offset();
 
-	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && kaslr_offset > 0) {
-		pr_emerg("Kernel Offset: 0x%llx from 0x%lx\n",
-			 kaslr_offset, KIMAGE_VADDR);
+	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && offset > 0) {
+		pr_emerg("Kernel Offset: 0x%lx from 0x%lx\n",
+			 offset, KIMAGE_VADDR);
 	} else {
 		pr_emerg("Kernel Offset: disabled\n");
 	}