Re: [PATCH v11 8/9] arm64: Add kernel return probes support (kretprobes)

[David Long]

On 03/17/2016 08:58 AM, 平松雅巳 / HIRAMATU，MASAMI wrote:
> > From: 平松雅巳 / HIRAMATU，MASAMI [mailto:masami.hiramatsu.pt@xxxxxxxxxxx]
> >
> > Hi,
> >
> > > From: Sandeepa Prabhu <sandeepa.s.prabhu@xxxxxxxxx>
> > >
> > > The pre-handler of this special 'trampoline' kprobe executes the return
> > > probe handler functions and restores original return address in ELR_EL1.
> > > This way the saved pt_regs still hold the original register context to be
> > > carried back to the probed kernel function.
> >
> > This patch seems not well separated.
> >
> > > diff --git a/arch/arm64/kernel/kprobes.c b/arch/arm64/kernel/kprobes.c
> > > index bd3f233..13d3333 100644
> > > --- a/arch/arm64/kernel/kprobes.c
> > > +++ b/arch/arm64/kernel/kprobes.c
> >
> > [snip]
> >
> > > +void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
> > > +				      struct pt_regs *regs)
> > > +{
> > > +	ri->ret_addr = (kprobe_opcode_t *)regs->regs[30];
> > > +
> > > +	/* replace return addr (x30) with trampoline */
> > > +	regs->regs[30] = (long)&kretprobe_trampoline;
> >
> > So, where is the kretprobe_trampoline? It seems that function is
> > defined in other patch.
> >
> > > +}
> > > +
> > > +int __kprobes arch_trampoline_kprobe(struct kprobe *p)
> > > +{
> > > +	return 0;
> > > }
> >
> > And what this function is for??
>
> Ah, sorry, this was my fault. Yes, this function is required.
> But this implementation also means there is an asm-based trampoline
> function which should be included in this patch.
>
> David, could you tell me the repository which I can get the latest
> version of this series? I'd like to see the whole code of kprobes/arm64.
>
> Thank you,

It can be found in:

http://git.linaro.org/people/dave.long/linux.git

...in the kprobes64-v11 branch.

Thanks,
-dl