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) -- 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
