kprobes: remove dependency on CONFIG_MODULES

kprobes depended on CONFIG_MODULES because it has to allocate memory for
code.

Since code allocations are now implemented with execmem, kprobes can be
enabled in non-modular kernels.

Add #ifdef CONFIG_MODULE guards for the code dealing with kprobes inside
modules, make CONFIG_KPROBES select CONFIG_EXECMEM and drop the
dependency of CONFIG_KPROBES on CONFIG_MODULES.

Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
[mcgrof: rebase in light of NEED_TASKS_RCU ]
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

diff --git a/arch/Kconfig b/arch/Kconfig
index ee1ccbde50ef3eec1e10deb2135bc96b703b68a1..b34946d90e4bb1d806ccde5feb0b888b6f14c6bd 100644 (file)
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -60,9 +60,9 @@ config GENERIC_ENTRY
 
 config KPROBES
        bool "Kprobes"
-       depends on MODULES
        depends on HAVE_KPROBES
        select KALLSYMS
+       select EXECMEM
        select NEED_TASKS_RCU
        help
          Kprobes allows you to trap at almost any kernel address and

diff --git a/include/linux/module.h b/include/linux/module.h
index 1153b0d99a808876f7ba62d137e5095e1e92a954..ffa1c603163c29e6da27f2cb7ccea90c99206720 100644 (file)
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -605,6 +605,11 @@ static inline bool module_is_live(struct module *mod)
        return mod->state != MODULE_STATE_GOING;
 }
 
+static inline bool module_is_coming(struct module *mod)
+{
+        return mod->state == MODULE_STATE_COMING;
+}
+
 struct module *__module_text_address(unsigned long addr);
 struct module *__module_address(unsigned long addr);
 bool is_module_address(unsigned long addr);
@@ -857,6 +862,10 @@ void *dereference_module_function_descriptor(struct module *mod, void *ptr)
        return ptr;
 }
 
+static inline bool module_is_coming(struct module *mod)
+{
+       return false;
+}
 #endif /* CONFIG_MODULES */
 
 #ifdef CONFIG_SYSFS

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index ddd7cdc16edfc4baaa8d6c2ca627654fd6c6a074..ca2c6cbd42d219dd2d2b7d5e40b7bed12c32707c 100644 (file)
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1588,7 +1588,7 @@ static int check_kprobe_address_safe(struct kprobe *p,
        }
 
        /* Get module refcount and reject __init functions for loaded modules. */
-       if (*probed_mod) {
+       if (IS_ENABLED(CONFIG_MODULES) && *probed_mod) {
                /*
                 * We must hold a refcount of the probed module while updating
                 * its code to prohibit unexpected unloading.
@@ -1603,12 +1603,13 @@ static int check_kprobe_address_safe(struct kprobe *p,
                 * kprobes in there.
                 */
                if (within_module_init((unsigned long)p->addr, *probed_mod) &&
-                   (*probed_mod)->state != MODULE_STATE_COMING) {
+                   !module_is_coming(*probed_mod)) {
                        module_put(*probed_mod);
                        *probed_mod = NULL;
                        ret = -ENOENT;
                }
        }
+
 out:
        preempt_enable();
        jump_label_unlock();
@@ -2488,24 +2489,6 @@ int kprobe_add_area_blacklist(unsigned long start, unsigned long end)
        return 0;
 }
 
-/* Remove all symbols in given area from kprobe blacklist */
-static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)
-{
-       struct kprobe_blacklist_entry *ent, *n;
-
-       list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) {
-               if (ent->start_addr < start || ent->start_addr >= end)
-                       continue;
-               list_del(&ent->list);
-               kfree(ent);
-       }
-}
-
-static void kprobe_remove_ksym_blacklist(unsigned long entry)
-{
-       kprobe_remove_area_blacklist(entry, entry + 1);
-}
-
 int __weak arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
                                   char *type, char *sym)
 {
@@ -2570,6 +2553,25 @@ static int __init populate_kprobe_blacklist(unsigned long *start,
        return ret ? : arch_populate_kprobe_blacklist();
 }
 
+#ifdef CONFIG_MODULES
+/* Remove all symbols in given area from kprobe blacklist */
+static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)
+{
+       struct kprobe_blacklist_entry *ent, *n;
+
+       list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) {
+               if (ent->start_addr < start || ent->start_addr >= end)
+                       continue;
+               list_del(&ent->list);
+               kfree(ent);
+       }
+}
+
+static void kprobe_remove_ksym_blacklist(unsigned long entry)
+{
+       kprobe_remove_area_blacklist(entry, entry + 1);
+}
+
 static void add_module_kprobe_blacklist(struct module *mod)
 {
        unsigned long start, end;
@@ -2672,6 +2674,17 @@ static struct notifier_block kprobe_module_nb = {
        .priority = 0
 };
 
+static int kprobe_register_module_notifier(void)
+{
+       return register_module_notifier(&kprobe_module_nb);
+}
+#else
+static int kprobe_register_module_notifier(void)
+{
+       return 0;
+}
+#endif /* CONFIG_MODULES */
+
 void kprobe_free_init_mem(void)
 {
        void *start = (void *)(&__init_begin);
@@ -2731,7 +2744,7 @@ static int __init init_kprobes(void)
        if (!err)
                err = register_die_notifier(&kprobe_exceptions_nb);
        if (!err)
-               err = register_module_notifier(&kprobe_module_nb);
+               err = kprobe_register_module_notifier();
 
        kprobes_initialized = (err == 0);
        kprobe_sysctls_init();

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 14099cc17fc9ed5bfad51b5be14504ef790e50a6..2cb2a3951b4f3a3ca4bc7b9dce79a5a0229cc2ab 100644 (file)
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -111,6 +111,7 @@ static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk,
        return strncmp(module_name(mod), name, len) == 0 && name[len] == ':';
 }
 
+#ifdef CONFIG_MODULES
 static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
 {
        char *p;
@@ -129,6 +130,12 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
 
        return ret;
 }
+#else
+static inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
+{
+       return false;
+}
+#endif
 
 static bool trace_kprobe_is_busy(struct dyn_event *ev)
 {
@@ -670,6 +677,7 @@ end:
        return ret;
 }
 
+#ifdef CONFIG_MODULES
 /* Module notifier call back, checking event on the module */
 static int trace_kprobe_module_callback(struct notifier_block *nb,
                                       unsigned long val, void *data)
@@ -704,6 +712,16 @@ static struct notifier_block trace_kprobe_module_nb = {
        .notifier_call = trace_kprobe_module_callback,
        .priority = 1   /* Invoked after kprobe module callback */
 };
+static int trace_kprobe_register_module_notifier(void)
+{
+       return register_module_notifier(&trace_kprobe_module_nb);
+}
+#else
+static int trace_kprobe_register_module_notifier(void)
+{
+       return 0;
+}
+#endif /* CONFIG_MODULES */
 
 static int count_symbols(void *data, unsigned long unused)
 {
@@ -1933,7 +1951,7 @@ static __init int init_kprobe_trace_early(void)
        if (ret)
                return ret;
 
-       if (register_module_notifier(&trace_kprobe_module_nb))
+       if (trace_kprobe_register_module_notifier())
                return -EINVAL;
 
        return 0;