kprobes: Support NOKPROBE_SYMBOL() in modules

Support NOKPROBE_SYMBOL() in modules. NOKPROBE_SYMBOL() records only symbol
address in "_kprobe_blacklist" section in the module.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134059.771170126@linutronix.de

include/linux/module.h

@@ -492,6 +492,8 @@ struct module {
 #ifdef CONFIG_KPROBES
 	void *kprobes_text_start;
 	unsigned int kprobes_text_size;
+	unsigned long *kprobe_blacklist;
+	unsigned int num_kprobe_blacklist;
 #endif
 
 #ifdef CONFIG_LIVEPATCH

kernel/kprobes.c

@@ -2192,6 +2192,11 @@ static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)
 	}
 }
 
+static void kprobe_remove_ksym_blacklist(unsigned long entry)
+{
+	kprobe_remove_area_blacklist(entry, entry + 1);
+}
+
 int __init __weak arch_populate_kprobe_blacklist(void)
 {
 	return 0;
@@ -2231,6 +2236,12 @@ static int __init populate_kprobe_blacklist(unsigned long *start,
 static void add_module_kprobe_blacklist(struct module *mod)
 {
 	unsigned long start, end;
+	int i;
+
+	if (mod->kprobe_blacklist) {
+		for (i = 0; i < mod->num_kprobe_blacklist; i++)
+			kprobe_add_ksym_blacklist(mod->kprobe_blacklist[i]);
+	}
 
 	start = (unsigned long)mod->kprobes_text_start;
 	if (start) {
@@ -2242,6 +2253,12 @@ static void add_module_kprobe_blacklist(struct module *mod)
 static void remove_module_kprobe_blacklist(struct module *mod)
 {
 	unsigned long start, end;
+	int i;
+
+	if (mod->kprobe_blacklist) {
+		for (i = 0; i < mod->num_kprobe_blacklist; i++)
+			kprobe_remove_ksym_blacklist(mod->kprobe_blacklist[i]);
+	}
 
 	start = (unsigned long)mod->kprobes_text_start;
 	if (start) {

kernel/module.c

@@ -3197,6 +3197,9 @@ static int find_module_sections(struct module *mod, struct load_info *info)
 #ifdef CONFIG_KPROBES
 	mod->kprobes_text_start = section_objs(info, ".kprobes.text", 1,
 						&mod->kprobes_text_size);
+	mod->kprobe_blacklist = section_objs(info, "_kprobe_blacklist",
+						sizeof(unsigned long),
+						&mod->num_kprobe_blacklist);
 #endif
 	mod->extable = section_objs(info, "__ex_table",
 				    sizeof(*mod->extable), &mod->num_exentries);