From: Jisheng Zhang <Jisheng.Zhang@synaptics.com> To: Masami Hiramatsu <mhiramat@kernel.org> 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 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>
WARNING: multiple messages have this Message-ID (diff)
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> _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-08-20 2:06 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 2019-08-20 0:01 ` Masami Hiramatsu 2019-08-20 2:05 ` Jisheng Zhang [this message] 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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