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Date: Fri, 20 Mar 2009 02:11:15 +0100 From: Frederic Weisbecker <fweisbec@...il.com> To: Masami Hiramatsu <mhiramat@...hat.com> Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>, Ingo Molnar <mingo@...e.hu>, Jim Keniston <jkenisto@...ibm.com>, LKML <linux-kernel@...r.kernel.org>, systemtap-ml <systemtap@...rces.redhat.com> Subject: Re: [RFC][PATCH -tip 8/9] kprobes: support respawn probes for module probing On Thu, Mar 19, 2009 at 05:10:44PM -0400, Masami Hiramatsu wrote: > Add module_*probe API's to respawn probes on kernel modules. > kprobes which have been registered through register_module_*probe are > activated when the target module is loaded, and deactivated when unloading. > register_module_*probe require an activate_handler which is called right > before activating the probe, and if it returns !0, kprobes will be activated. > > Thus, users can check whether the target module is true target or not > (e.g. checking build-id) in activate_handler. > > Signed-off-by: Masami Hiramatsu <mhiramat@...hat.com> > Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com> > --- > include/linux/kprobes.h | 39 ++++++++ > kernel/kprobes.c | 250 +++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 289 insertions(+), 0 deletions(-) > > diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h > index 2ec6cc1..9d47d08 100644 > --- a/include/linux/kprobes.h > +++ b/include/linux/kprobes.h > @@ -37,6 +37,7 @@ > #include <linux/spinlock.h> > #include <linux/rcupdate.h> > #include <linux/mutex.h> > +#include <linux/module.h> > > #ifdef CONFIG_KPROBES > #include <asm/kprobes.h> > @@ -69,6 +70,7 @@ typedef int (*kprobe_fault_handler_t) (struct kprobe *, struct pt_regs *, > int trapnr); > typedef int (*kretprobe_handler_t) (struct kretprobe_instance *, > struct pt_regs *); > +typedef int (*probe_activate_handler_t)(void *, struct module *); I guess it could also be useful to call the handler when the module is unloaded. Be using another parameter with a LOAD/UNLOAD enum value. > > struct kprobe { > struct hlist_node hlist; > @@ -279,6 +281,16 @@ void unregister_kretprobes(struct kretprobe **rps, int num); > void kprobe_flush_task(struct task_struct *tk); > void recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head); > > +int register_module_kprobe(struct kprobe *kp, > + probe_activate_handler_t handler, void *data); > +int register_module_kretprobe(struct kretprobe *rp, > + probe_activate_handler_t handler, void *data); > +int register_module_jprobe(struct jprobe *jp, > + probe_activate_handler_t handler, void *data); > +void unregister_module_kprobe(struct kprobe *kp); > +void unregister_module_kretprobe(struct kretprobe *rp); > +void unregister_module_jprobe(struct jprobe *jp); > + > #else /* !CONFIG_KPROBES: */ > > static inline int kprobes_built_in(void) > @@ -345,5 +357,32 @@ static inline void unregister_kretprobes(struct kretprobe **rps, int num) > static inline void kprobe_flush_task(struct task_struct *tk) > { > } > +static inline int register_module_kprobe(struct kprobe *kp, > + probe_activate_handler_t handler, > + void *data) > +{ > + return -ENOSYS; > +} > +static inline int register_module_kretprobe(struct kretprobe *rp, > + probe_activate_handler_t handler, > + void *data) > +{ > + return -ENOSYS; > +} > +static inline int register_module_jprobe(struct jprobe *jp, > + probe_activate_handler_t handler, > + void *data) > +{ > + return -ENOSYS; > +} > +void unregister_module_kprobe(struct kprobe *kp) > +{ > +} > +void unregister_module_kretprobe(struct kretprobe *rp) > +{ > +} > +void unregister_module_jprobe(struct jprobe *jp) > +{ > +} Shouldn't the unregister_* be inlined too? I think they all could be static inlined too in case of !CONFIG_MODULE > #endif /* CONFIG_KPROBES */ > #endif /* _LINUX_KPROBES_H */ > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 5016bfb..f16a54e 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -1416,6 +1416,256 @@ static int __kprobes debugfs_kprobe_init(void) > late_initcall(debugfs_kprobe_init); > #endif /* CONFIG_DEBUG_FS */ > > +/* Kprobes module respawn support */ > +enum probe_type { > + PROBE_TYPE_KPROBE, > + PROBE_TYPE_KRETPROBE, > + PROBE_TYPE_JPROBE, > +}; > + > +struct module_probe_client { > + struct list_head list; > + const char *module; /* including symbol name */ > + int active; > + void *data; > + probe_activate_handler_t handler; > + enum probe_type type; > + union { > + struct kprobe *kp; > + struct kretprobe *rp; > + struct jprobe *jp; > + }; > +}; #ifdef CONFIG_MODULE ? Frederic. > +static DEFINE_MUTEX(module_probe_mutex); > +static LIST_HEAD(module_probe_list); > + > +static int activate_module_probe(struct module_probe_client *pc) > +{ > + int ret = 0; > + if (pc->active) > + return 0; > + switch (pc->type) { > + case PROBE_TYPE_KPROBE: > + ret = register_kprobe(pc->kp); > + break; > + case PROBE_TYPE_KRETPROBE: > + ret = register_kretprobe(pc->rp); > + break; > + case PROBE_TYPE_JPROBE: > + ret = register_jprobe(pc->jp); > + break; > + default: > + WARN_ON(1); > + break; > + } > + if (!ret) > + pc->active = 1; > + return ret; > +} > + > +static void deactivate_module_probe(struct module_probe_client *pc) > +{ > + if (!pc->active) > + return; > + switch (pc->type) { > + case PROBE_TYPE_KPROBE: > + unregister_kprobe(pc->kp); > + break; > + case PROBE_TYPE_KRETPROBE: > + unregister_kretprobe(pc->rp); > + break; > + case PROBE_TYPE_JPROBE: > + unregister_jprobe(pc->jp); > + break; > + default: > + WARN_ON(1); > + break; > + } > + pc->active = 0; > +} > + > +static const char *probed_module_name(struct kprobe *kp) > +{ > + if ((kp->symbol_name) && strchr(kp->symbol_name, ':')) > + return kp->symbol_name; > + return NULL; > +} > + > +static int module_is_exist(const char *module) > +{ > + char buf[MODULE_NAME_LEN + 8]; > + snprintf(buf, MODULE_NAME_LEN + 8, "%s:__stext", module); > + return module_kallsyms_lookup_name(buf) ? 1 : 0; > +} > + > +static int add_module_probe(const char *module, void *p, enum probe_type type, > + probe_activate_handler_t handler, void *data) > +{ > + struct module_probe_client *pc; > + int ret = 0; > + > + if (!handler) > + return -EINVAL; > + > + pc = kzalloc(sizeof(struct module_probe_client), GFP_KERNEL); > + pc->kp = p; > + pc->type = type; > + pc->module = module; > + pc->handler = handler; > + pc->data = data; > + INIT_LIST_HEAD(&pc->list); > + > + mutex_lock(&module_probe_mutex); > + if (module_is_exist(module)) > + ret = activate_module_probe(pc); > + if (ret) > + kfree(pc); > + else > + list_add_tail(&pc->list, &module_probe_list); > + mutex_unlock(&module_probe_mutex); > + return ret; > +} > + > +static void __del_module_probe(struct module_probe_client *pc) > +{ > + list_del(&pc->list); > + deactivate_module_probe(pc); > + kfree(pc); > +} > + > +static int del_module_probe(void *p) > +{ > + struct module_probe_client *pc; > + int ret; > + > + mutex_lock(&module_probe_mutex); > + list_for_each_entry(pc, &module_probe_list, list) > + if (pc->kp == p) { > + /* don't need safe loop, we exit soon */ > + __del_module_probe(pc); > + goto found; > + } > + ret = -ENOENT; > +found: > + mutex_unlock(&module_probe_mutex); > + return ret; > +} > + > +int __kprobes > +register_module_kprobe(struct kprobe *kp, > + probe_activate_handler_t handler, void *data) > +{ > + const char *module; > + module = probed_module_name(kp); > + if (!module) > + return register_kprobe(kp); > + return add_module_probe(module, kp, PROBE_TYPE_KPROBE, > + handler, data); > +} > +EXPORT_SYMBOL_GPL(register_module_kprobe); > + > +int __kprobes > +register_module_kretprobe(struct kretprobe *rp, > + probe_activate_handler_t handler, void *data) > +{ > + const char *module; > + module = probed_module_name(&rp->kp); > + if (!module) > + return register_kretprobe(rp); > + return add_module_probe(module, rp, PROBE_TYPE_KRETPROBE, > + handler, data); > +} > +EXPORT_SYMBOL_GPL(register_module_kretprobe); > + > +int __kprobes > +register_module_jprobe(struct jprobe *jp, > + probe_activate_handler_t handler, void *data) > +{ > + const char *module; > + module = probed_module_name(&jp->kp); > + if (!module) > + return register_jprobe(jp); > + return add_module_probe(module, jp, PROBE_TYPE_JPROBE, > + handler, data); > +} > +EXPORT_SYMBOL_GPL(register_module_jprobe); > + > +void __kprobes unregister_module_kprobe(struct kprobe *kp) > +{ > + const char *module; > + module = probed_module_name(kp); > + if (!module) > + unregister_kprobe(kp); > + else > + del_module_probe(kp); > +} > +EXPORT_SYMBOL_GPL(unregister_module_kprobe); > + > +void __kprobes unregister_module_kretprobe(struct kretprobe *rp) > +{ > + const char *module; > + module = probed_module_name(&rp->kp); > + if (!module) > + unregister_kretprobe(rp); > + else > + del_module_probe(rp); > +} > +EXPORT_SYMBOL_GPL(unregister_module_kretprobe); > + > +void __kprobes unregister_module_jprobe(struct jprobe *jp) > +{ > + const char *module; > + module = probed_module_name(&jp->kp); > + if (!module) > + unregister_jprobe(jp); > + else > + del_module_probe(jp); > +} > +EXPORT_SYMBOL_GPL(unregister_module_jprobe); > + > +static int module_is_probed(const char *mod, const char *sym) > +{ > + int len = strlen(mod); > + return strncmp(mod, sym, len) == 0 && sym[len] == ':'; > +} > + > +static int module_probe_callback(struct notifier_block *nb, > + unsigned long state, void *module) > +{ > + struct module_probe_client *pc; > + struct module *mod = module; > + if (state == MODULE_STATE_LIVE) > + return NOTIFY_DONE; > + > + mutex_lock(&module_probe_mutex); > + list_for_each_entry(pc, &module_probe_list, list) { > + if (!module_is_probed(mod->name, pc->module)) > + continue; > + if (state == MODULE_STATE_COMING && > + pc->handler(pc->data, module)) { > + activate_module_probe(pc); > + } else if (state == MODULE_STATE_GOING) > + deactivate_module_probe(pc); > + } > + mutex_unlock(&module_probe_mutex); > + return NOTIFY_DONE; > +} > + > +struct notifier_block module_probe_nb = { > + .notifier_call = module_probe_callback > +}; > + > +static int __init init_module_probes(void) > +{ > + int ret; > + ret = register_module_notifier(&module_probe_nb); > + if (ret) > + pr_warning("Failed to register module notifier\n"); > + return ret; > +} > +module_init(init_module_probes); > + > module_init(init_kprobes); > > EXPORT_SYMBOL_GPL(register_kprobe); > -- > Masami Hiramatsu > > Software Engineer > Hitachi Computer Products (America) Inc. > Software Solutions Division > > e-mail: mhiramat@...hat.com > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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