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From: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Jonathan Corbet <corbet@lwn.net>, Will Deacon <will@kernel.org>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
	Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 1/3] kprobes/x86: use instruction_pointer and instruction_pointer_set
Date: Wed, 21 Aug 2019 02:02:23 +0000	[thread overview]
Message-ID: <20190821095109.34c8a47f@xhacker.debian> (raw)
In-Reply-To: <20190820132110.GP2332@hirez.programming.kicks-ass.net>

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

WARNING: multiple messages have this Message-ID (diff)
From: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>,
	Catalin Marinas <catalin.marinas@arm.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Will Deacon <will@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 1/3] kprobes/x86: use instruction_pointer and instruction_pointer_set
Date: Wed, 21 Aug 2019 02:02:23 +0000	[thread overview]
Message-ID: <20190821095109.34c8a47f@xhacker.debian> (raw)
In-Reply-To: <20190820132110.GP2332@hirez.programming.kicks-ass.net>

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

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2019-08-21  2:02 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-20  3:50 [PATCH v2 0/3] arm64: KPROBES_ON_FTRACE Jisheng Zhang
2019-08-20  3:50 ` Jisheng Zhang
2019-08-20  3:52 ` [PATCH v2 1/3] kprobes/x86: use instruction_pointer and instruction_pointer_set Jisheng Zhang
2019-08-20  3:52   ` Jisheng Zhang
2019-08-20  8:53   ` Thomas Gleixner
2019-08-20  8:53     ` Thomas Gleixner
2019-08-20  9:02     ` Jisheng Zhang
2019-08-20  9:02       ` Jisheng Zhang
2019-08-20  9:20       ` Jisheng Zhang
2019-08-20  9:20         ` Jisheng Zhang
2019-08-20 13:21       ` Peter Zijlstra
2019-08-20 13:21         ` Peter Zijlstra
2019-08-21  2:02         ` Jisheng Zhang [this message]
2019-08-21  2:02           ` Jisheng Zhang
2019-08-21  1:52       ` Masami Hiramatsu
2019-08-21  1:52         ` Masami Hiramatsu
2019-08-21  2:09         ` Jisheng Zhang
2019-08-21  2:09           ` Jisheng Zhang
2019-08-23 14:51           ` Masami Hiramatsu
2019-08-23 14:51             ` Masami Hiramatsu
2019-08-20  3:53 ` [PATCH v2 2/3] kprobes: adjust kprobe addr for KPROBES_ON_FTRACE Jisheng Zhang
2019-08-20  3:53   ` Jisheng Zhang
2019-08-20 10:15   ` Naveen N. Rao
2019-08-20 10:15     ` Naveen N. Rao
2019-08-20 10:41     ` Jisheng Zhang
2019-08-20 10:41       ` Jisheng Zhang
2019-08-21  2:07   ` Masami Hiramatsu
2019-08-21  2:07     ` Masami Hiramatsu
2019-08-21  2:50     ` Jisheng Zhang
2019-08-21  2:50       ` Jisheng Zhang
2019-08-20  3:54 ` [PATCH v2 3/3] arm64: implement KPROBES_ON_FTRACE Jisheng Zhang
2019-08-20  3:54   ` Jisheng Zhang
2019-08-20  7:17   ` Jisheng Zhang
2019-08-20  7:17     ` Jisheng Zhang
2019-08-20  8:53   ` Thomas Gleixner
2019-08-20  8:53     ` Thomas Gleixner

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