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From: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@redhat.com>,
	"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>,
	Mark Rutland <mark.rutland@arm.com>,
	Jonathan Corbet <corbet@lwn.net>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>
Subject: [PATCH v7 1/3] kprobes/ftrace: Use ftrace_location() when [dis]arming probes
Date: Wed, 25 Dec 2019 09:42:07 +0000	[thread overview]
Message-ID: <20191225172752.70be1dc1@xhacker.debian> (raw)
In-Reply-To: <20191225172625.69811b3e@xhacker.debian>

Ftrace location could include more than a single instruction in case
of some architectures (powerpc64, for now). In this case, kprobe is
permitted on any of those instructions, and uses ftrace infrastructure
for functioning.

However, [dis]arm_kprobe_ftrace() uses the kprobe address when setting
up ftrace filter IP. This won't work if the address points to any
instruction apart from the one that has a branch to _mcount(). To
resolve this, have [dis]arm_kprobe_ftrace() use ftrace_function() to
identify the filter IP.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 kernel/kprobes.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 53534aa258a6..5c630b424e3a 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -986,9 +986,10 @@ static int prepare_kprobe(struct kprobe *p)
 static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
 			       int *cnt)
 {
+	unsigned long ftrace_ip = ftrace_location((unsigned long)p->addr);
 	int ret = 0;
 
-	ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0);
+	ret = ftrace_set_filter_ip(ops, ftrace_ip, 0, 0);
 	if (ret) {
 		pr_debug("Failed to arm kprobe-ftrace at %pS (%d)\n",
 			 p->addr, ret);
@@ -1011,7 +1012,7 @@ static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
 	 * At this point, sinec ops is not registered, we should be sefe from
 	 * registering empty filter.
 	 */
-	ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
+	ftrace_set_filter_ip(ops, ftrace_ip, 1, 0);
 	return ret;
 }
 
@@ -1028,6 +1029,7 @@ static int arm_kprobe_ftrace(struct kprobe *p)
 static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
 				  int *cnt)
 {
+	unsigned long ftrace_ip = ftrace_location((unsigned long)p->addr);
 	int ret = 0;
 
 	if (*cnt == 1) {
@@ -1038,7 +1040,7 @@ static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
 
 	(*cnt)--;
 
-	ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
+	ret = ftrace_set_filter_ip(ops, ftrace_ip, 1, 0);
 	WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (%d)\n",
 		  p->addr, ret);
 	return ret;
-- 
2.24.1


  reply	other threads:[~2019-12-25  9:42 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-25  9:40 [PATCH v7 0/3] arm64: implement KPROBES_ON_FTRACE Jisheng Zhang
2019-12-25  9:42 ` Jisheng Zhang [this message]
2019-12-25  9:46   ` [PATCH v7 1/3] kprobes/ftrace: Use ftrace_location() when [dis]arming probes Jisheng Zhang
2019-12-25  9:42 ` [PATCH v7 2/3] ftrace: introduce FTRACE_IP_EXTENSION Jisheng Zhang
2019-12-26  2:45   ` Masami Hiramatsu
2020-01-08  0:05   ` Steven Rostedt
2019-12-25  9:44 ` [PATCH v7 3/3] arm64: implement KPROBES_ON_FTRACE Jisheng Zhang
2019-12-26  2:57   ` Masami Hiramatsu
2019-12-26  3:18     ` Jisheng Zhang
2019-12-26  4:25       ` Jisheng Zhang
2019-12-26  9:26         ` Masami Hiramatsu
2020-07-21 13:24           ` Masami Hiramatsu
2020-07-24  7:06             ` Jisheng Zhang
2020-07-24 16:54               ` Masami Hiramatsu
2020-02-28 15:31   ` Mark Rutland

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