mark kernel_set_to_readonly as __ro_after_init

This change was extracted from PaX where it's part of KERNEXEC.

Signed-off-by: Daniel Micay <danielmicay@gmail.com>

Author: thestinger

arch/x86/mm/init_32.c

@@ -872,7 +872,7 @@ int arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
 #endif
 #endif
 
-int kernel_set_to_readonly __read_mostly;
+int kernel_set_to_readonly __ro_after_init;
 
 void set_kernel_text_rw(void)
 {
@@ -924,12 +924,11 @@ void mark_rodata_ro(void)
 	unsigned long start = PFN_ALIGN(_text);
 	unsigned long size = (unsigned long)__end_rodata - start;
 
+	kernel_set_to_readonly = 1;
 	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
 	pr_info("Write protecting kernel text and read-only data: %luk\n",
 		size >> 10);
 
-	kernel_set_to_readonly = 1;
-
 #ifdef CONFIG_CPA_DEBUG
 	pr_info("Testing CPA: Reverting %lx-%lx\n", start, start + size);
 	set_pages_rw(virt_to_page(start), size >> PAGE_SHIFT);

arch/x86/mm/init_64.c

@@ -1206,7 +1206,7 @@ void __init mem_init(void)
 	mem_init_print_info(NULL);
 }
 
-int kernel_set_to_readonly;
+int kernel_set_to_readonly __ro_after_init;
 
 void set_kernel_text_rw(void)
 {
@@ -1255,9 +1255,8 @@ void mark_rodata_ro(void)
 
 	printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
 	       (end - start) >> 10);
-	set_memory_ro(start, (end - start) >> PAGE_SHIFT);
-
 	kernel_set_to_readonly = 1;
+	set_memory_ro(start, (end - start) >> PAGE_SHIFT);
 
 	/*
 	 * The rodata/data/bss/brk section (but not the kernel text!)