> > --- a/arch/powerpc/lib/code-patching.c
> > +++ b/arch/powerpc/lib/code-patching.c
> > @@ -23,11 +23,33 @@
> > #include <asm/code-patching.h>
> > #include <asm/setup.h>
> >
> > +
>
> This blank line is not needed
Ack
>
> > +static inline bool in_init_section(unsigned int *patch_addr)
> > +{
> > + if (patch_addr < (unsigned int *)__init_begin)
> > + return false;
> > + if (patch_addr >= (unsigned int *)__init_end)
> > + return false;
> > + return true;
> > +}
>
> Can we use the existing function init_section_contains() instead of this
> new function ?
Nice, I was looking for something like that...
> > +
> > +static inline bool init_freed(void)
> > +{
> > + return (system_state >= SYSTEM_RUNNING);
> > +}
> > +
>
> I would call this function differently, for instance init_is_finished(),
> because as you mentionned it doesn't exactly mean that init memory is freed.
Talking to Nick and mpe offline I think we are going to have to add a flag when
we free init mem rather than doing what we have now since what we have now has a
potential race. That change will eliminate the function entirely.
> > static int __patch_instruction(unsigned int *exec_addr, unsigned int
> > instr,
> > unsigned int *patch_addr)
> > {
> > int err;
> >
> > + /* Make sure we aren't patching a freed init section */
> > + if (in_init_section(patch_addr) && init_freed()) {
>
> The test must be done on exec_addr, not on patch_addr, as patch_addr is
> the address where the instruction as been remapped RW for allowing its
> modification.
Thanks for the catch
> Also I think it should be tested the other way round, because the
> init_freed() is a simpler test which will be false most of the time once
> the system is running so it should be checked first.
ok, I'll change.
> > + printk(KERN_DEBUG "Skipping init section patching addr:
> > 0x%lx\n",
>
> Maybe use pr_debug() instead.
Sure.
>
> > + (unsigned long)patch_addr);
>
> Please align second line as per Codying style.
Sorry I can't see what's wrong. You're (or Cody :-P) going to have to spell it
this out for me...
>
> > + return 0;
> > + }
> > +
> > __put_user_size(instr, patch_addr, 4, err);
> > if (err)
> > return err;
> >
>
> I think it would be better to put this verification in
> patch_instruction() instead, to avoid RW mapping/unmapping the
> instruction to patch when we are not going to do the patching.
If we do it there then we miss the raw_patch_intruction case.
IMHO I don't think we need to optimise this rare and non-critical path.
Mikey
