Messages in this thread | | | Date | Mon, 25 Jun 2018 11:09:15 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v12 01/11] x86: text_poke() may access uninitialized struct pages |
| |
On Mon, Jun 25, 2018 at 10:39:24AM +0200, Thomas Gleixner wrote: > On Mon, 25 Jun 2018, Peter Zijlstra wrote: > > On Thu, Jun 21, 2018 at 05:25:08PM -0400, Pavel Tatashin wrote: > > > -void *text_poke(void *addr, const void *opcode, size_t len) > > > +void __ref *text_poke(void *addr, const void *opcode, size_t len) > > > { > > > unsigned long flags; > > > char *vaddr; > > > struct page *pages[2]; > > > int i; > > > > > > + /* While boot memory allocator is runnig we cannot use struct > > > > Broken comment style.. > > > > > + * pages as they are not yet initialized. However, we also know > > > + * that this is early in boot, and it is safe to fallback to > > > + * text_poke_early. > > > + */ > > > + if (unlikely(!after_bootmem)) > > > + return text_poke_early(addr, opcode, len); > > > > I'm not entirely sure this is right.. Because not only do we need the > > whole fixmap stuff working, we also need #DB and the IPI handlers set-up > > and working. > > IPI? That's early UP boot why would you need an IPI?
Because the way this is called is from __jump_label_transform() -> text_poke_bp() -> text_poke() -> text_poke_early().
And if you look at text_poke_bp(), you'll note it relies on #DB and on_each_cpu() IPIs.
Which is of course exactly the reason I avoided text_poke_bp() entirely in the first place.
| |