x86: make sure initmem is writable

When we free initmem, various rodata and CPA checks may have left
memory read only.. this patch ensures that the memory is writable
before we free it.
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

arch/x86/mm/init_32.c

@@ -780,6 +780,13 @@ void free_init_pages(char *what, unsigned long begin, unsigned long end)
 {
 	unsigned long addr;
 
+	/*
+	 * We just marked the kernel text read only above, now that
+	 * we are going to free part of that, we need to make that
+	 * writeable first.
+	 */
+	set_memory_rw(begin, (end - begin) >> PAGE_SHIFT);
+
 	for (addr = begin; addr < end; addr += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(addr));
 		init_page_count(virt_to_page(addr));

arch/x86/mm/init_64.c

@@ -570,6 +570,7 @@ void free_init_pages(char *what, unsigned long begin, unsigned long end)
 	 * 2Mb kernel mapping just for this debug feature.
 	 */
 	if (begin >= __START_KERNEL_map) {
+		set_memory_rw(begin, (end - begin)/PAGE_SIZE);
 		set_memory_np(begin, (end - begin)/PAGE_SIZE);
 		set_memory_nx(begin, (end - begin)/PAGE_SIZE);
 	}