Re: [PATCH 1/4] kprobes: adjust kprobe addr for KPROBES_ON_FTRACE

[Jisheng Zhang <Jisheng.Zhang@synaptics.com>]

On Mon, 19 Aug 2019 22:13:02 +0530 "Naveen N. Rao"  wrote:

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> 
> 
> Jisheng Zhang wrote:
> > For KPROBES_ON_FTRACE case, we need to adjust the kprobe's addr
> > correspondingly.
> >
> > Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
> > ---
> >  kernel/kprobes.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> > index 9873fc627d61..f8400753a8a9 100644
> > --- a/kernel/kprobes.c
> > +++ b/kernel/kprobes.c
> > @@ -1560,6 +1560,9 @@ int register_kprobe(struct kprobe *p)
> >       addr = kprobe_addr(p);
> >       if (IS_ERR(addr))
> >               return PTR_ERR(addr);
> > +#ifdef CONFIG_KPROBES_ON_FTRACE
> > +     addr = (kprobe_opcode_t *)ftrace_call_adjust((unsigned long)addr);
> > +#endif
> >       p->addr = addr;  
> 
> I'm not sure what this is achieving, but looks wrong to me.

Indeed, I didn't take care of non-ftrace addr when KPROBES_ON_FTRACE, will
update in next version.

thanks

> 
> If you intend to have kprobes default to using ftrace entry for probing
> functions, consider over-riding kprobe_lookup_name() -- see powerpc
> variant for example.
> 
> 
> - Naveen
>