From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Nicholas Piggin <npiggin@gmail.com>
Cc: <linuxppc-dev@lists.ozlabs.org>, <linux-kernel@vger.kernel.org>
Subject: [PATCH 6/7] kprobes/ftrace: Use ftrace_location() when [dis]arming probes
Date: Tue, 18 Jun 2019 20:17:05 +0530 [thread overview]
Message-ID: <4fedad69107b7fd81b9324315ce4fbf6287e5084.1560868106.git.naveen.n.rao@linux.vnet.ibm.com> (raw)
In-Reply-To: <cover.1560868106.git.naveen.n.rao@linux.vnet.ibm.com>
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>
---
kernel/kprobes.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 445337c107e0..282ee704e2d8 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -978,10 +978,10 @@ static int prepare_kprobe(struct kprobe *p)
/* Caller must lock kprobe_mutex */
static int arm_kprobe_ftrace(struct kprobe *p)
{
+ unsigned long ftrace_ip = ftrace_location((unsigned long)p->addr);
int ret = 0;
- ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
- (unsigned long)p->addr, 0, 0);
+ ret = ftrace_set_filter_ip(&kprobe_ftrace_ops, ftrace_ip, 0, 0);
if (ret) {
pr_debug("Failed to arm kprobe-ftrace at %pS (%d)\n",
p->addr, ret);
@@ -1005,13 +1005,14 @@ static int arm_kprobe_ftrace(struct kprobe *p)
* non-empty filter_hash for IPMODIFY ops, we're safe from an accidental
* empty filter_hash which would undesirably trace all functions.
*/
- ftrace_set_filter_ip(&kprobe_ftrace_ops, (unsigned long)p->addr, 1, 0);
+ ftrace_set_filter_ip(&kprobe_ftrace_ops, ftrace_ip, 1, 0);
return ret;
}
/* Caller must lock kprobe_mutex */
static int disarm_kprobe_ftrace(struct kprobe *p)
{
+ unsigned long ftrace_ip = ftrace_location((unsigned long)p->addr);
int ret = 0;
if (kprobe_ftrace_enabled == 1) {
@@ -1022,8 +1023,7 @@ static int disarm_kprobe_ftrace(struct kprobe *p)
kprobe_ftrace_enabled--;
- ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
- (unsigned long)p->addr, 1, 0);
+ ret = ftrace_set_filter_ip(&kprobe_ftrace_ops, ftrace_ip, 1, 0);
WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (%d)\n",
p->addr, ret);
return ret;
--
2.22.0
next prev parent reply other threads:[~2019-06-18 14:49 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-18 14:46 [PATCH 0/7] powerpc/ftrace: Patch out -mprofile-kernel instructions Naveen N. Rao
2019-06-18 14:47 ` [PATCH 1/7] ftrace: Expose flags used for ftrace_replace_code() Naveen N. Rao
2019-06-18 14:47 ` [PATCH 2/7] x86/ftrace: Fix use of flags in ftrace_replace_code() Naveen N. Rao
2019-06-18 14:47 ` [PATCH 3/7] ftrace: Expose __ftrace_replace_code() Naveen N. Rao
2019-06-18 14:47 ` [PATCH 4/7] powerpc/ftrace: Additionally nop out the preceding mflr with -mprofile-kernel Naveen N. Rao
2019-06-19 5:14 ` Michael Ellerman
2019-06-19 7:10 ` Nicholas Piggin
2019-06-19 9:53 ` Naveen N. Rao
2019-06-19 10:41 ` Nicholas Piggin
2019-06-19 17:14 ` Naveen N. Rao
2019-06-18 14:47 ` [PATCH 5/7] powerpc/ftrace: Update ftrace_location() for powerpc -mprofile-kernel Naveen N. Rao
2019-06-18 15:45 ` Steven Rostedt
2019-06-18 18:11 ` Naveen N. Rao
2019-06-18 18:23 ` Naveen N. Rao
2019-06-18 18:32 ` Steven Rostedt
2019-06-19 7:56 ` Naveen N. Rao
2019-06-19 9:28 ` Steven Rostedt
2019-06-18 14:47 ` Naveen N. Rao [this message]
2019-06-21 14:41 ` [PATCH 6/7] kprobes/ftrace: Use ftrace_location() when [dis]arming probes Masami Hiramatsu
2019-06-18 14:47 ` [PATCH 7/7] powerpc/kprobes: Allow probing on any ftrace address Naveen N. Rao
2019-06-21 14:50 ` Masami Hiramatsu
2019-06-22 3:49 ` Joe Perches
2019-06-26 9:39 ` Naveen N. Rao
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