From 94462ad3b14739d158a1ab87bb30008c1e5a6bc1 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 29 Nov 2010 13:15:42 -0500 Subject: [PATCH] module: Move RO/NX module protection to after ftrace module update The commit: 84e1c6bb38eb318e456558b610396d9f1afaabf0 x86: Add RO/NX protection for loadable kernel modules Broke the function tracer with this output: ------------[ 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: [] warn_slowpath_common+0x85/0x9d [] ? __process_new_adapter+0x7/0x34 [i2c_core] [] ? __process_new_adapter+0x7/0x34 [i2c_core] [] warn_slowpath_null+0x1a/0x1c [] ftrace_bug+0x114/0x171 [] ? __process_new_adapter+0x7/0x34 [i2c_core] [] ftrace_process_locs+0x1ae/0x274 [] ? __process_new_adapter+0x7/0x34 [i2c_core] [] ftrace_module_notify+0x39/0x44 [] notifier_call_chain+0x37/0x63 [] __blocking_notifier_call_chain+0x46/0x5b [] blocking_notifier_call_chain+0x14/0x16 [] sys_init_module+0x73/0x1f3 [] system_call_fastpath+0x16/0x1b ---[ end trace 2aff4f4ca53ec746 ]--- ftrace faulted on writing [] __process_new_adapter+0x7/0x34 [i2c_core] The cause was that the module text was set to read only before ftrace could convert the calls to mcount to nops. Thus, the conversions failed due to not being able to write to the text locations. The simple fix is to move setting the module to read only after the module notifiers are called (where ftrace sets the module mcounts to nops). Reported-by: Peter Zijlstra Acked-by: Rusty Russell Signed-off-by: Steven Rostedt --- kernel/module.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 562f665c721f..34e00b708fad 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2816,18 +2816,6 @@ 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; @@ -2888,6 +2876,18 @@ 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) -- 2.20.1