Hi, Le Mon, 29 Nov 2010 13:15:42 -0500, Steven Rostedt <rostedt@xxxxxxxxxxx> a écrit : > This patch breaks function tracer: > > ------------[ cut here ]------------ > WARNING: at kernel/trace/ftrace.c:1014 ftrace_bug+0x114/0x171() > Hardware name: Precision WorkStation 470 > Modules linked in: i2c_core(+) > Pid: 86, comm: modprobe Not tainted 2.6.37-rc2+ #68 > Call Trace: > [<ffffffff8104e957>] warn_slowpath_common+0x85/0x9d > [<ffffffffa00026db>] ? __process_new_adapter+0x7/0x34 [i2c_core] > [<ffffffffa00026db>] ? __process_new_adapter+0x7/0x34 [i2c_core] > [<ffffffff8104e989>] warn_slowpath_null+0x1a/0x1c > [<ffffffff810a9dfe>] ftrace_bug+0x114/0x171 > [<ffffffffa00026db>] ? __process_new_adapter+0x7/0x34 [i2c_core] > [<ffffffff810aa0db>] ftrace_process_locs+0x1ae/0x274 > [<ffffffffa00026db>] ? __process_new_adapter+0x7/0x34 [i2c_core] > [<ffffffff810aa29e>] ftrace_module_notify+0x39/0x44 > [<ffffffff814405cf>] notifier_call_chain+0x37/0x63 > [<ffffffff8106e054>] __blocking_notifier_call_chain+0x46/0x5b > [<ffffffff8106e07d>] blocking_notifier_call_chain+0x14/0x16 > [<ffffffff8107ffde>] sys_init_module+0x73/0x1f3 > [<ffffffff8100acf2>] system_call_fastpath+0x16/0x1b > ---[ end trace 2aff4f4ca53ec746 ]--- > ftrace faulted on writing [<ffffffffa00026db>] > __process_new_adapter+0x7/0x34 [i2c_core] > > > On Tue, Nov 16, 2010 at 10:35:16PM +0100, matthieu castet wrote: > > > > @@ -2650,6 +2810,18 @@ static struct module *load_module(void > > __user *umod, kfree(info.strmap); > > free_copy(&info); > > > > + /* Set RO and NX regions for core */ > > + set_section_ro_nx(mod->module_core, > > + mod->core_text_size, > > + mod->core_ro_size, > > + mod->core_size); > > + > > + /* Set RO and NX regions for init */ > > + set_section_ro_nx(mod->module_init, > > + mod->init_text_size, > > + mod->init_ro_size, > > + mod->init_size); > > + > > Here we set the text read only before we call the notifiers. The > function tracer changes the calls to mcount into nops via a notifier > call so this must be done after the module notifiers. > > > /* Done! */ > > trace_module_load(mod); > > return mod; > > @@ -2753,6 +2925,7 @@ SYSCALL_DEFINE3(init_module, void __user *, > > umod, mod->symtab = mod->core_symtab; > > mod->strtab = mod->core_strtab; > > #endif > > + unset_section_ro_nx(mod, mod->module_init); > > module_free(mod, mod->module_init); > > mod->module_init = NULL; > > mod->init_size = 0; > > Below is the patch that fixes this bug. > > -- Steve > > Reported-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> > Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx> > > diff --git a/kernel/module.c b/kernel/module.c > index ba421e6..5ccf52c 100644 > --- a/kernel/module.c > +++ b/kernel/module.c > @@ -2804,18 +2804,6 @@ static struct module *load_module(void __user > *umod, kfree(info.strmap); > free_copy(&info); > > - /* Set RO and NX regions for core */ > - set_section_ro_nx(mod->module_core, > - mod->core_text_size, > - mod->core_ro_size, > - mod->core_size); > - > - /* Set RO and NX regions for init */ > - set_section_ro_nx(mod->module_init, > - mod->init_text_size, > - mod->init_ro_size, > - mod->init_size); > - > /* Done! */ > trace_module_load(mod); > return mod; > @@ -2876,6 +2864,18 @@ SYSCALL_DEFINE3(init_module, void __user *, > umod, blocking_notifier_call_chain(&module_notify_list, > MODULE_STATE_COMING, mod); > > + /* Set RO and NX regions for core */ > + set_section_ro_nx(mod->module_core, > + mod->core_text_size, > + mod->core_ro_size, > + mod->core_size); > + > + /* Set RO and NX regions for init */ > + set_section_ro_nx(mod->module_init, > + mod->init_text_size, > + mod->init_ro_size, > + mod->init_size); > + > do_mod_ctors(mod); > /* Start the module */ > if (mod->init != NULL) > > That's look fine for me. But I wonder why ftrace_arch_code_modify_prepare isn't called ? It is only called when we start/stop tracing ? Matthieu -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
