Messages in this thread | | | Date | Wed, 22 Sep 2010 11:28:34 -0400 | From | Jason Baron <> | Subject | Re: [PATCH 2/2] Rewrite jump_label.c to use binary search |
| |
On Wed, Sep 22, 2010 at 11:02:50AM -0400, Mathieu Desnoyers wrote: > * Andi Kleen (andi@firstfloor.org) wrote: > > > > > > > >>> + for (; entry < stop && entry->key == key; entry++) > > >>> + if (kernel_text_address(entry->code)) > > >> > > >> This does not work for modules I'm afraid, only for the core kernel. You > > >> should test for __module_text_address() somewhere. > > > > > > I thought it was shared now, but ok. > > > > Double checked. This is ok because kernel_text_address() > > already checks for modules. You were probably thinking > > of __kernel_text_address() > > Ah right, > > Although we have another problem: > > __module_text_address() includes module init text, which defeats the > purpose of the check put in there by Jason. > > So the check works for the core kernel, but not for modules. > > Mathieu >
it works for modules too...it does:
struct module *__module_text_address(unsigned long addr) { struct module *mod = __module_address(addr); if (mod) { /* Make sure it's within the text section. */ if (!within(addr, mod->module_init, mod->init_text_size) && !within(addr, mod->module_core, mod->core_text_size)) mod = NULL; } return mod; }
and then in kernel/module.c we have :
module_free(mod, mod->module_init); mod->module_init = NULL;
So, I was relying on the fact module_init gets set to NULL after the free happens. However, there a small race there in that the vfree() happens before module_init() is set to NULL. So that is probably most easily fixed be wrapping those two lines with the jump_label_mutex.
thanks,
-Jason
| |