Randy,
Thanks for looking at this. I implemented your suggestions and also
changed EXPORT_SYMBOL to EXPORT_SYMBOL_GPL.
On Fri, 2006-08-04 at 09:00 -0700, Randy.Dunlap wrote:
> On Fri, 04 Aug 2006 10:17:32 -0500 David Smith wrote:
>
> > When inserting a kprobes probe into a loadable module, there isn't a way
> > for the kprobes module to get a module reference (in order to find the
> > base address of the module among perhaps other things).
> >
> > A kprobes probe needs the base address of the module in order to
> > "relocate" the addresses of probe points (since the load address of the
> > module can change from run to run of the kprobe).
> >
> > I've added a new function, module_get_byname(), that looks up a module
> > by name and returns the module reference. Note that module_get_byname()
> > also increments the module reference count. It does this so that the
> > module won't be unloaded between the time that module_get_byname() is
> > called and register_kprobe() is called.
...
Signed off by David Smith <[email protected]>
----
diff --git a/include/linux/module.h b/include/linux/module.h
index 0dfb794..9953a38 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -374,6 +374,8 @@ extern void __module_put_and_exit(struct
__attribute__((noreturn));
#define module_put_and_exit(code) __module_put_and_exit(THIS_MODULE,
code);
+int module_get_byname(const char *mod_name, struct module **mod);
+
#ifdef CONFIG_MODULE_UNLOAD
unsigned int module_refcount(struct module *mod);
void __symbol_put(const char *symbol);
@@ -549,6 +551,11 @@ static inline int is_exported(const char
return 0;
}
+static inline int module_get_byname(const char *mod_name, struct module
**mod)
+{
+ return 1;
+}
+
static inline int register_module_notifier(struct notifier_block * nb)
{
/* no events will happen anyway, so this can always succeed */
diff --git a/kernel/module.c b/kernel/module.c
index 2a19cd4..473cc0b 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -291,7 +291,27 @@ static struct module *find_module(const
}
return NULL;
}
+
+int module_get_byname(const char *mod_name, struct module **mod)
+{
+ *mod = NULL;
+ /* We must hold module_mutex before calling find_module(). */
+ if (mutex_lock_interruptible(&module_mutex) != 0)
+ return -EINTR;
+
+ *mod = find_module(mod_name);
+ mutex_unlock(&module_mutex);
+ if (*mod) {
+ if (!strong_try_module_get(*mod)) {
+ *mod = NULL;
+ return -EINVAL;
+ }
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(module_get_byname);
+
#ifdef CONFIG_SMP
/* Number of blocks used and allocated. */
static unsigned int pcpu_num_used, pcpu_num_allocated;
-
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