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From: Masami Hiramatsu <mhiramat@kernel.org>
To: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"David S. Miller" <davem@davemloft.net>,
	Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
	"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	"x86@kernel.org" <x86@kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/4] kprobes: adjust kprobe addr for KPROBES_ON_FTRACE
Date: Tue, 20 Aug 2019 09:01:30 +0900	[thread overview]
Message-ID: <20190820090130.844fc064030db67efb05ceb1@kernel.org> (raw)
In-Reply-To: <20190819192505.483c0bf0@xhacker.debian>

Hi Jisheng,

On Mon, 19 Aug 2019 11:36:09 +0000
Jisheng Zhang <Jisheng.Zhang@synaptics.com> wrote:

> For KPROBES_ON_FTRACE case, we need to adjust the kprobe's addr
> correspondingly.

No, I think you have misunderstood what the ftrace_call_adjust() does.
Ftrace's rec->ip is already adjusted when initializing it. Kprobes
checks the list after initialized (adjusted). So you don't need to
adjust it again.

BTW, this type of hidden adjustment should be avoided by design.
If you find user specifies wrong address, return error instead of
adjust it silently.

Thank you,

> 
> 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;
>  
>  	ret = check_kprobe_rereg(p);
> -- 
> 2.23.0.rc1
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>

WARNING: multiple messages have this Message-ID (diff)
From: Masami Hiramatsu <mhiramat@kernel.org>
To: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	"x86@kernel.org" <x86@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>,
	Steven Rostedt <rostedt@goodmis.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 1/4] kprobes: adjust kprobe addr for KPROBES_ON_FTRACE
Date: Tue, 20 Aug 2019 09:01:30 +0900	[thread overview]
Message-ID: <20190820090130.844fc064030db67efb05ceb1@kernel.org> (raw)
In-Reply-To: <20190819192505.483c0bf0@xhacker.debian>

Hi Jisheng,

On Mon, 19 Aug 2019 11:36:09 +0000
Jisheng Zhang <Jisheng.Zhang@synaptics.com> wrote:

> For KPROBES_ON_FTRACE case, we need to adjust the kprobe's addr
> correspondingly.

No, I think you have misunderstood what the ftrace_call_adjust() does.
Ftrace's rec->ip is already adjusted when initializing it. Kprobes
checks the list after initialized (adjusted). So you don't need to
adjust it again.

BTW, this type of hidden adjustment should be avoided by design.
If you find user specifies wrong address, return error instead of
adjust it silently.

Thank you,

> 
> 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;
>  
>  	ret = check_kprobe_rereg(p);
> -- 
> 2.23.0.rc1
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>

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

  parent reply	other threads:[~2019-08-20  0:01 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-19 11:35 [PATCH 0/4] arm64: KPROBES_ON_FTRACE Jisheng Zhang
2019-08-19 11:35 ` Jisheng Zhang
2019-08-19 11:36 ` [PATCH 1/4] kprobes: adjust kprobe addr for KPROBES_ON_FTRACE Jisheng Zhang
2019-08-19 11:36   ` Jisheng Zhang
2019-08-19 16:43   ` Naveen N. Rao
2019-08-19 16:43     ` Naveen N. Rao
2019-08-20  1:51     ` Jisheng Zhang
2019-08-20  1:51       ` Jisheng Zhang
2019-08-20  0:01   ` Masami Hiramatsu [this message]
2019-08-20  0:01     ` Masami Hiramatsu
2019-08-20  2:05     ` Jisheng Zhang
2019-08-20  2:05       ` Jisheng Zhang
2019-08-19 11:36 ` [PATCH 2/4] kprobes/x86: use instruction_pointer and instruction_pointer_set Jisheng Zhang
2019-08-19 11:36   ` Jisheng Zhang
2019-08-20  0:09   ` Masami Hiramatsu
2019-08-20  0:09     ` Masami Hiramatsu
2019-08-19 11:37 ` [PATCH 3/4] kprobes: move kprobe_ftrace_handler() from x86 and make it weak Jisheng Zhang
2019-08-19 11:37   ` Jisheng Zhang
2019-08-20  0:07   ` Masami Hiramatsu
2019-08-20  0:07     ` Masami Hiramatsu
2019-08-20  1:56     ` Jisheng Zhang
2019-08-20  1:56       ` Jisheng Zhang
2019-08-19 11:38 ` [PATCH 4/4] arm64: implement KPROBES_ON_FTRACE Jisheng Zhang
2019-08-19 11:38   ` Jisheng Zhang
2019-08-19 16:52   ` Naveen N. Rao
2019-08-19 16:52     ` Naveen N. Rao
2019-08-20  2:16     ` Jisheng Zhang
2019-08-20  2:16       ` Jisheng Zhang
2019-08-19 12:53 ` [PATCH 0/4] arm64: KPROBES_ON_FTRACE Mark Rutland
2019-08-19 12:53   ` Mark Rutland
2019-08-19 13:10 ` Masami Hiramatsu
2019-08-19 13:10   ` Masami Hiramatsu

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