module: __module_address

Impact: New API, cleanup

ksplice wants to know the bounds of a module, not just the module text.

It makes sense to have __module_address.  We then implement
is_module_address and __module_text_address in terms of this (and
change is_module_text_address() to bool while we're at it).

Also, add proper kerneldoc for them all.

Cc: Anders Kaseorg <andersk@mit.edu>
Cc: Jeff Arnold <jbarnold@mit.edu>
Cc: Tim Abbott <tabbott@mit.edu>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

2 files changed, 73 insertions, 23 deletions

diff --git a/include/linux/module.h b/include/linux/module.h
index 08e5e75d6122..fd1241e1416f 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -365,7 +365,9 @@ static inline int module_is_live(struct module *mod)
 /* Is this address in a module? (second is with no locks, for oops) */
 struct module *module_text_address(unsigned long addr);
 struct module *__module_text_address(unsigned long addr);
-int is_module_address(unsigned long addr);
+struct module *__module_address(unsigned long addr);
+bool is_module_address(unsigned long addr);
+bool is_module_text_address(unsigned long addr);
 
 static inline int within_module_core(unsigned long addr, struct module *mod)
 {
@@ -494,21 +496,29 @@ search_module_extables(unsigned long addr)
         return NULL;
 }
 
-/* Is this address in a module? */
 static inline struct module *module_text_address(unsigned long addr)
 {
         return NULL;
 }
 
-/* Is this address in a module? (don't take a lock, we're oopsing) */
+static inline struct module *__module_address(unsigned long addr)
+{
+        return NULL;
+}
+
 static inline struct module *__module_text_address(unsigned long addr)
 {
         return NULL;
 }
 
-static inline int is_module_address(unsigned long addr)
+static inline bool is_module_address(unsigned long addr)
 {
-        return 0;
+        return false;
+}
+
+static inline bool is_module_text_address(unsigned long addr)
+{
+        return false;
 }
 
 /* Get/put a kernel symbol (calls should be symmetric) */
diff --git a/kernel/module.c b/kernel/module.c
index 2f0fddf3c114..bd15a94f91c1 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -76,7 +76,7 @@ static DECLARE_WAIT_QUEUE_HEAD(module_wq);
 
 static BLOCKING_NOTIFIER_HEAD(module_notify_list);
 
-/* Bounds of module allocation, for speeding __module_text_address */
+/* Bounds of module allocation, for speeding __module_address */
 static unsigned long module_addr_min = -1UL, module_addr_max = 0;
 
 int register_module_notifier(struct notifier_block * nb)
@@ -2745,29 +2745,31 @@ const struct exception_table_entry *search_module_extables(unsigned long addr)
 }
 
 /*
- * Is this a valid module address?
+ * is_module_address - is this address inside a module?
+ * @addr: the address to check.
+ *
+ * See is_module_text_address() if you simply want to see if the address
+ * is code (not data).
  */
-int is_module_address(unsigned long addr)
+bool is_module_address(unsigned long addr)
 {
-        struct module *mod;
+        bool ret;
 
         preempt_disable();
-
-        list_for_each_entry_rcu(mod, &modules, list) {
-                if (within_module_core(addr, mod)) {
-                        preempt_enable();
-                        return 1;
-                }
-        }
-
+        ret = __module_address(addr) != NULL;
         preempt_enable();
 
-        return 0;
+        return ret;
 }
 
-
-/* Is this a valid kernel address? */
-__notrace_funcgraph struct module *__module_text_address(unsigned long addr)
+/*
+ * __module_address - get the module which contains an address.
+ * @addr: the address.
+ *
+ * Must be called with preempt disabled or module mutex held so that
+ * module doesn't get freed during this.
+ */
+__notrace_funcgraph struct module *__module_address(unsigned long addr)
 {
         struct module *mod;
 
@@ -2775,12 +2777,50 @@ __notrace_funcgraph struct module *__module_text_address(unsigned long addr)
                 return NULL;
 
         list_for_each_entry_rcu(mod, &modules, list)
-                if (within(addr, mod->module_init, mod->init_text_size)
-                    || within(addr, mod->module_core, mod->core_text_size))
+                if (within_module_core(addr, mod)
+                    || within_module_init(addr, mod))
                         return mod;
         return NULL;
 }
 
+/*
+ * is_module_text_address - is this address inside module code?
+ * @addr: the address to check.
+ *
+ * See is_module_address() if you simply want to see if the address is
+ * anywhere in a module.  See kernel_text_address() for testing if an
+ * address corresponds to kernel or module code.
+ */
+bool is_module_text_address(unsigned long addr)
+{
+        bool ret;
+
+        preempt_disable();
+        ret = __module_text_address(addr) != NULL;
+        preempt_enable();
+
+        return ret;
+}
+
+/*
+ * __module_text_address - get the module whose code contains an address.
+ * @addr: the address.
+ *
+ * Must be called with preempt disabled or module mutex held so that
+ * module doesn't get freed during this.
+ */
+struct module *__module_text_address(unsigned long addr)
+{
+        struct module *mod = __module_address(addr);
+        if (mod) {
+                /* Make sure it's within the text section. */
+                if (!within(addr, mod->module_init, mod->init_text_size)
+                    && !within(addr, mod->module_core, mod->core_text_size))
+                        mod = NULL;
+        }
+        return mod;
+}
+
 struct module *module_text_address(unsigned long addr)
 {
         struct module *mod;