Subject: Re: [PATCH v2 1/3] kprobes/x86: use instruction_pointer and instruction_pointer_set

From: Jisheng Zhang <[email-masked]>
Date: Wed, 21 Aug 2019 02:02:23 +0000

Hi Peter,

On Tue, 20 Aug 2019 15:21:10 +0200 Peter Zijlstra wrote:

> 
> 
> On Tue, Aug 20, 2019 at 09:02:59AM +0000, Jisheng Zhang wrote:
> > In v2, actually, the arm64 version's kprobe_ftrace_handler() is the same
> > as x86's, the only difference is comment, e.g
> >
> > /* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
> >
> > while in arm64
> >
> > /* Kprobe handler expects regs->pc = ip + 1 as breakpoint hit */  
> 
> What's weird; I thought ARM has fixed sized instructions and they are
> all 4 bytes? So how does a single byte offset make sense for ARM?

I believe the "+1" here means + one kprobe_opcode_t.

Thanks

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