From: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
To: Masami Hiramatsu <mhiramat@kernel.org>
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 02:05:58 +0000 [thread overview]
Message-ID: <20190820095450.3eb3120b@xhacker.debian> (raw)
In-Reply-To: <20190820090130.844fc064030db67efb05ceb1@kernel.org>
On Tue, 20 Aug 2019 09:01:30 +0900 Masami Hiramatsu wrote:
>
> Hi Jisheng,
Hi,
>
> 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.
This is not to adjust the ftarce's rec->ip, but to adjust the struct kprobe
addr member. Because check_kprobe_address_safe()=>arch_check_ftrace_location
will check the kprobe's addr with ftrace's rec->ip. Since ftrace's rec->ip
is already adjusted, there will be mismatch if we don't adjust kprobe's addr
correspondingly.
However, this patch is wrong. I should not update the kprobe's addr
for non-ftrace-entry. Will fix this in next version.
Thanks
>
> 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>
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next prev parent reply other threads:[~2019-08-20 2:06 UTC|newest]
Thread overview: 16+ 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 11:36 ` [PATCH 1/4] kprobes: adjust kprobe addr for KPROBES_ON_FTRACE Jisheng Zhang
2019-08-19 16:43 ` Naveen N. Rao
2019-08-20 1:51 ` Jisheng Zhang
2019-08-20 0:01 ` Masami Hiramatsu
2019-08-20 2:05 ` Jisheng Zhang [this message]
2019-08-19 11:36 ` [PATCH 2/4] kprobes/x86: use instruction_pointer and instruction_pointer_set Jisheng Zhang
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
2019-08-20 0:07 ` Masami Hiramatsu
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 16:52 ` Naveen N. Rao
2019-08-20 2:16 ` Jisheng Zhang
2019-08-19 12:53 ` [PATCH 0/4] arm64: KPROBES_ON_FTRACE Mark Rutland
2019-08-19 13:10 ` Masami Hiramatsu
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