Revert "x86, 64bit, mm: Mark data/bss/brk to nx"

This reverts commit e105c818 which
was commit 72212675 upstream.

This caused suspend/resume to stop working on at least some systems -
specifically, the system would reboot when woken.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Steven Rostedt <rostedt@goodmis.org>

arch/x86/mm/init_64.c

@@ -778,7 +778,6 @@ void mark_rodata_ro(void)
 	unsigned long text_end = PAGE_ALIGN((unsigned long) &__stop___ex_table);
 	unsigned long rodata_end = PAGE_ALIGN((unsigned long) &__end_rodata);
 	unsigned long data_start = (unsigned long) &_sdata;
-	unsigned long all_end = PFN_ALIGN(&_end);
 
 	printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
 	       (end - start) >> 10);
@@ -787,10 +786,10 @@ void mark_rodata_ro(void)
 	kernel_set_to_readonly = 1;
 
 	/*
-	 * The rodata/data/bss/brk section (but not the kernel text!)
-	 * should also be not-executable.
+	 * The rodata section (but not the kernel text!) should also be
+	 * not-executable.
 	 */
-	set_memory_nx(rodata_start, (all_end - rodata_start) >> PAGE_SHIFT);
+	set_memory_nx(rodata_start, (end - rodata_start) >> PAGE_SHIFT);
 
 	rodata_test();