x86: check vmlinux limits, 64-bit

these build-time and link-time checks would have prevented the
vmlinux size regression.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/head64.c

@@ -82,6 +82,19 @@ void __init x86_64_start_kernel(char * real_mode_data)
 {
 	int i;
 
+	/*
+	 * Build-time sanity checks on the kernel image and module
+	 * area mappings. (these are purely build-time and produce no code)
+	 */
+	BUILD_BUG_ON(MODULES_VADDR < KERNEL_IMAGE_START);
+	BUILD_BUG_ON(MODULES_VADDR-KERNEL_IMAGE_START < KERNEL_IMAGE_SIZE);
+	BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
+	BUILD_BUG_ON((KERNEL_IMAGE_START & ~PMD_MASK) != 0);
+	BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
+	BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
+	BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
+				(__START_KERNEL & PGDIR_MASK)));
+
 	/* clear bss before set_intr_gate with early_idt_handler */
 	clear_bss();
 

arch/x86/kernel/vmlinux_64.lds.S

@@ -247,3 +247,9 @@ SECTIONS
 
   DWARF_DEBUG
 }
+
+/*
+ * Build-time check on the image size:
+ */
+ASSERT((_end - _text <= KERNEL_IMAGE_SIZE),
+	"kernel image bigger than KERNEL_IMAGE_SIZE")

arch/x86/mm/fault.c

@@ -976,9 +976,5 @@ void vmalloc_sync_all(void)
 		if (address == start)
 			start = address + PGDIR_SIZE;
 	}
-	/* Check that there is no need to do the same for the modules area. */
-	BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
-	BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
-				(__START_KERNEL & PGDIR_MASK)));
 #endif
 }