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Rao" To: Michael Ellerman , Steven Rostedt , Masami Hiramatsu , Ingo Molnar , Nicholas Piggin Subject: [PATCH v2 6/7] kprobes/ftrace: Use ftrace_location() when [dis]arming probes Date: Thu, 27 Jun 2019 16:53:54 +0530 X-Mailer: git-send-email 2.22.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19062711-0016-0000-0000-0000028CD924 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19062711-0017-0000-0000-000032EA5663 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-06-27_06:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906270133 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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. Acked-by: Masami Hiramatsu Signed-off-by: Naveen N. Rao --- 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