Messages in this thread Patch in this message | | | Subject | Re: [PATCH] module interface improvement for kprobes | From | David Smith <> | Date | Fri, 04 Aug 2006 14:51:01 -0500 |
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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 <dsmith@redhat.com>
---- 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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