Thread (18 messages) 18 messages, 5 authors, 2019-08-23

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

From: Jisheng Zhang <hidden>
Date: 2019-08-21 02:09:20
Also in: linux-doc, lkml

Hi,

On Wed, 21 Aug 2019 10:52:47 +0900 Masami Hiramatsu wrote:

Hi Jisheng,

On Tue, 20 Aug 2019 09:02:59 +0000
Jisheng Zhang [off-list ref] wrote:
quoted
Hi Thomas,

On Tue, 20 Aug 2019 10:53:58 +0200 (CEST) Thomas Gleixner wrote:
 
quoted

On Tue, 20 Aug 2019, Jisheng Zhang wrote:
 
quoted
This is to make the x86 kprobe_ftrace_handler() more common so that
the code could be reused in future.  
While I agree with the change in general, I can't find anything which
reuses that code. So the change log is pretty useless and I have no idea
how this is related to the rest of the series.  
In v1, this code is moved from x86 to common kprobes.c [1]
But I agree with Masami, consolidation could be done when arm64 kprobes
on ftrace is stable.  
We'll revisit to consolidate the code after we got 3rd or 4th clones.
quoted
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 */  
As Peter pointed, on arm64, is that really 1 or 4 bytes?
This part is heavily depends on the processor software-breakpoint
implementation.
Per my understanding, the "+1" here means "+ one kprobe_opcode_t".
quoted

W/ above, any suggestion about the suitable change log?  
I think you just need to keep the first half of the description.
Since this patch itself is not related to the series, could you update
the description and resend it as a single cleanup patch out of the series?
Got it. Will do today.

Thanks a lot

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