On Tue, 20 Aug 2019 15:45:24 +0530 "Naveen N. Rao" wrote:
>
>
> Jisheng Zhang wrote:
> > For KPROBES_ON_FTRACE case, we need to adjust the kprobe's addr
> > correspondingly.
> >
> > Signed-off-by: Jisheng Zhang <Jisheng.Zhang@xxxxxxxxxxxxx>
> > ---
> > kernel/kprobes.c | 10 +++++++---
> > 1 file changed, 7 insertions(+), 3 deletions(-)
> >
> > diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> > index 9873fc627d61..3fd2f68644da 100644
> > --- a/kernel/kprobes.c
> > +++ b/kernel/kprobes.c
> > @@ -1484,15 +1484,19 @@ static inline int check_kprobe_rereg(struct kprobe *p)
> >
> > int __weak arch_check_ftrace_location(struct kprobe *p)
> > {
> > - unsigned long ftrace_addr;
> > + unsigned long ftrace_addr, addr = (unsigned long)p->addr;
> >
> > - ftrace_addr = ftrace_location((unsigned long)p->addr);
> > +#ifdef CONFIG_KPROBES_ON_FTRACE
> > + addr = ftrace_call_adjust(addr);
> > +#endif
>
> Looking at the commit message for patch 3/3, it looks like you want the
> probe to be placed on ftrace entry by default, and this patch seems to
> be aimed at that.
Yeah.
>
> If so, this is not the right approach. As I mentioned previously, you
> would want to over-ride kprobe_lookup_name(). This ensures that the
> address is changed only if the user provided a symbol, and not if the
> user wanted to probe at a very specific address. See commit
Great! Now I understand the reason.
> 24bd909e94776 ("powerpc/kprobes: Prefer ftrace when probing function
> entry").
Now, I got your meaning. You are right. I will update the patch in newer
version.
Thanks a lot!
>
> If this patch is for some other purpose, then it isn't clear from the
> commit log. Please provide a better explanation.
>
>
> - Naveen
>
