Update module to use livepatch

module.c

@@ -1,63 +1,45 @@
 #include <linux/module.h>
 #include <linux/kernel.h>
-#include <linux/kallsyms.h>
-#include <linux/slab.h>
-
-#if defined __i386__
-#define ASM_HOOK_CODE "\x68\x00\x00\x00\x00\xc3" // push 0x00000000, ret
-#define ASM_HOOK_CODE_OFFSET 1
-#elif defined __x86_64__
-#define ASM_HOOK_CODE "\x48\xb8\x00\x00\x00\x00\x00\x00\x00\x00\xff\xe0" // mov rax 0x0000000000000000, jmp rax
-#define ASM_HOOK_CODE_OFFSET 2
-#else
-#error ARCH_ERROR_MESSAGE
-#endif
-
-static void *original_devmem_function = NULL;
-static char original_function_code_backup[sizeof(ASM_HOOK_CODE) - 1];
+#include <linux/livepatch.h>
+
+#include <linux/seq_file.h>
+
 
 int modified_devmem_function(unsigned long pagenr)
 {
     return 1;
 }
 
-int init_module(void)
-{
-    original_devmem_function = (void *)kallsyms_lookup_name("devmem_is_allowed");
-    if (!original_devmem_function)
+static struct klp_func funcs[] = {
     {
-        printk(KERN_INFO "Can't locate the needed symbol, is it exported?\n");
-        return -1;
-    }
+        .old_name = "devmem_is_allowed",
+        .new_func = modified_devmem_function,
+    }, { }
+};
 
-    preempt_disable();
-    write_cr0(read_cr0() & (~0x10000)); //disable write-protected memory
-
-    memcpy(original_function_code_backup, original_devmem_function, sizeof(ASM_HOOK_CODE) - 1);
-    memcpy(original_devmem_function, ASM_HOOK_CODE, sizeof(ASM_HOOK_CODE) - 1);
-    *(void **)&((char *)original_devmem_function)[ASM_HOOK_CODE_OFFSET] = modified_devmem_function;
+static struct klp_object objs[] = {
+    {
+        /* name being NULL means vmlinux */
+        .funcs = funcs,
+    }, { }
+};
 
-    write_cr0(read_cr0() | 0x10000); // enable write-protected memory
-    preempt_enable();
+static struct klp_patch patch = {
+    .mod = THIS_MODULE,
+    .objs = objs,
+};
 
-    printk(KERN_INFO "Memory access module loaded\n");
-    return 0;
+static int livepatch_init(void)
+{
+    return klp_enable_patch(&patch);
 }
 
-void cleanup_module(void)
+static void livepatch_exit(void)
 {
-    preempt_disable();
-    write_cr0(read_cr0() & (~0x10000)); //disable write-protected memory
-
-    memcpy(original_devmem_function, original_function_code_backup, sizeof(ASM_HOOK_CODE) - 1);
-
-    write_cr0(read_cr0() | 0x10000); // enable write-protected memory
-    preempt_enable();
-
-    printk(KERN_INFO "Memory access module unloaded\n");
 }
 
-MODULE_AUTHOR("Ozgun Ayaz");
-MODULE_DESCRIPTION("make /dev/mem writable beyond the first 1 MB");
+module_init(livepatch_init);
+module_exit(livepatch_exit);
 MODULE_LICENSE("GPL");
-MODULE_INFO(intree, "Y"); //bullshit lol
+MODULE_DESCRIPTION("make /dev/mem writable beyond the first 1 MB");
+MODULE_INFO(livepatch, "Y");