Messages in this thread Patch in this message | | | Date | Tue, 15 Oct 2019 09:28:02 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH v3 5/6] x86/ftrace: Use text_poke() |
| |
On Fri, 11 Oct 2019 14:59:03 +0200 Peter Zijlstra <peterz@infradead.org> wrote:
> On Thu, Oct 10, 2019 at 07:28:19PM +0200, Peter Zijlstra wrote: > > > Really the best solution is to move all the poking into > > ftrace_module_init(), before we mark it RO+X. That's what I'm going to > > do for jump_label and static_call as well, I just need to add that extra > > notifier callback. > > OK, so I started writing that patch... or rather, I wrote the patch and > started on the Changelog when I ran into trouble describing why we need > it. > > That is, I'm struggling to explain why we cannot flip > prepare_coming_module() and complete_formation(). > > Yes, it breaks ftrace, but I'm thinking that is all it breaks. So let me > see if we can cure that.
You are mainly worried about making text that is executable into read-write again. What if we kept my one patch that just changed the module in ftrace_module_enable() from read-only to read-write, but before we ever set it executable.
Jessica, would this patch break anything?
It moves the setting of the module execution to after calling both ftrace_module_enable() and klp_module_coming().
This would make it possible to do the module code and still keep with the no executable code becoming writable.
-- Steve
diff --git a/kernel/module.c b/kernel/module.c index ff2d7359a418..6e2fd40a6ed9 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3728,7 +3728,6 @@ static int complete_formation(struct module *mod, struct load_info *info) module_enable_ro(mod, false); module_enable_nx(mod); - module_enable_x(mod); /* Mark state as coming so strong_try_module_get() ignores us, * but kallsyms etc. can see us. */ @@ -3751,6 +3750,11 @@ static int prepare_coming_module(struct module *mod) if (err) return err; + /* Make module executable after ftrace is enabled */ + mutex_lock(&module_mutex); + module_enable_x(mod); + mutex_unlock(&module_mutex); + blocking_notifier_call_chain(&module_notify_list, MODULE_STATE_COMING, mod); return 0;
| |