2 files changed, 72 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index adea3a22fa00..9973a7e2e0ac 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1312,6 +1312,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         for working out where the kernel is dying during
                         startup.
 
+        initcall_blacklist=  [KNL] Do not execute a comma-separated list of
+                        initcall functions.  Useful for debugging built-in
+                        modules and initcalls.
+
         initrd=         [BOOT] Specify the location of the initial ramdisk
 
         inport.irq=     [HW] Inport (ATI XL and Microsoft) busmouse driver
diff --git a/init/main.c b/init/main.c
index 9d3a7b84de5c..8ac3833f2bdf 100644
--- a/init/main.c
+++ b/init/main.c
@@ -77,6 +77,7 @@
 #include <linux/sched_clock.h>
 #include <linux/context_tracking.h>
 #include <linux/random.h>
+#include <linux/list.h>
 
 #include <asm/io.h>
 #include <asm/bugs.h>
@@ -665,6 +666,70 @@ static void __init do_ctors(void)
 bool initcall_debug;
 core_param(initcall_debug, initcall_debug, bool, 0644);
 
+#ifdef CONFIG_KALLSYMS
+struct blacklist_entry {
+        struct list_head next;
+        char *buf;
+};
+
+static __initdata_or_module LIST_HEAD(blacklisted_initcalls);
+
+static int __init initcall_blacklist(char *str)
+{
+        char *str_entry;
+        struct blacklist_entry *entry;
+
+        /* str argument is a comma-separated list of functions */
+        do {
+                str_entry = strsep(&str, ",");
+                if (str_entry) {
+                        pr_debug("blacklisting initcall %s\n", str_entry);
+                        entry = alloc_bootmem(sizeof(*entry));
+                        entry->buf = alloc_bootmem(strlen(str_entry) + 1);
+                        strcpy(entry->buf, str_entry);
+                        list_add(&entry->next, &blacklisted_initcalls);
+                }
+        } while (str_entry);
+
+        return 0;
+}
+
+static bool __init_or_module initcall_blacklisted(initcall_t fn)
+{
+        struct list_head *tmp;
+        struct blacklist_entry *entry;
+        char *fn_name;
+
+        fn_name = kasprintf(GFP_KERNEL, "%pf", fn);
+        if (!fn_name)
+                return false;
+
+        list_for_each(tmp, &blacklisted_initcalls) {
+                entry = list_entry(tmp, struct blacklist_entry, next);
+                if (!strcmp(fn_name, entry->buf)) {
+                        pr_debug("initcall %s blacklisted\n", fn_name);
+                        kfree(fn_name);
+                        return true;
+                }
+        }
+
+        kfree(fn_name);
+        return false;
+}
+#else
+static int __init initcall_blacklist(char *str)
+{
+        pr_warn("initcall_blacklist requires CONFIG_KALLSYMS\n");
+        return 0;
+}
+
+static bool __init_or_module initcall_blacklisted(initcall_t fn)
+{
+        return false;
+}
+#endif
+__setup("initcall_blacklist=", initcall_blacklist);
+
 static int __init_or_module do_one_initcall_debug(initcall_t fn)
 {
         ktime_t calltime, delta, rettime;
@@ -689,6 +754,9 @@ int __init_or_module do_one_initcall(initcall_t fn)
         int ret;
         char msgbuf[64];
 
+        if (initcall_blacklisted(fn))
+                return -EPERM;
+
         if (initcall_debug)
                 ret = do_one_initcall_debug(fn);
         else