From: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
To: srikar@linux.vnet.ibm.com, oleg@redhat.com, rostedt@goodmis.org,
mhiramat@kernel.org, liu.song.a23@gmail.com
Cc: peterz@infradead.org, mingo@redhat.com, acme@kernel.org,
alexander.shishkin@linux.intel.com, jolsa@redhat.com,
namhyung@kernel.org, linux-kernel@vger.kernel.org,
ananth@linux.vnet.ibm.com, alexis.berlemont@gmail.com,
naveen.n.rao@linux.vnet.ibm.com,
linux-arm-kernel@lists.infradead.org, linux-mips@linux-mips.org,
linux@armlinux.org.uk, ralf@linux-mips.org, paul.burton@mips.com,
Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Subject: [PATCH v8 5/6] trace_uprobe/sdt: Prevent multiple reference counter for same uprobe
Date: Thu, 9 Aug 2018 09:48:55 +0530 [thread overview]
Message-ID: <20180809041856.1547-6-ravi.bangoria@linux.ibm.com> (raw)
In-Reply-To: <20180809041856.1547-1-ravi.bangoria@linux.ibm.com>
We assume to have only one reference counter for one uprobe.
Don't allow user to add multiple trace_uprobe entries having
same inode+offset but different reference counter.
Ex,
# echo "p:sdt_tick/loop2 /home/ravi/tick:0x6e4(0x10036)" > uprobe_events
# echo "p:sdt_tick/loop2_1 /home/ravi/tick:0x6e4(0xfffff)" >> uprobe_events
bash: echo: write error: Invalid argument
# dmesg
trace_kprobe: Reference counter offset mismatch.
There is one exception though:
When user is trying to replace the old entry with the new
one, we allow this if the new entry does not conflict with
any other existing entries.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
---
kernel/trace/trace_uprobe.c | 37 +++++++++++++++++++++++++++++++++++--
1 file changed, 35 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index bf2be098eb08..be64d943d7ea 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -324,6 +324,35 @@ static int unregister_trace_uprobe(struct trace_uprobe *tu)
return 0;
}
+/*
+ * Uprobe with multiple reference counter is not allowed. i.e.
+ * If inode and offset matches, reference counter offset *must*
+ * match as well. Though, there is one exception: If user is
+ * replacing old trace_uprobe with new one(same group/event),
+ * then we allow same uprobe with new reference counter as far
+ * as the new one does not conflict with any other existing
+ * ones.
+ */
+static struct trace_uprobe *find_old_trace_uprobe(struct trace_uprobe *new)
+{
+ struct trace_uprobe *tmp, *old = NULL;
+ struct inode *new_inode = d_real_inode(new->path.dentry);
+
+ old = find_probe_event(trace_event_name(&new->tp.call),
+ new->tp.call.class->system);
+
+ list_for_each_entry(tmp, &uprobe_list, list) {
+ if ((old ? old != tmp : true) &&
+ new_inode == d_real_inode(tmp->path.dentry) &&
+ new->offset == tmp->offset &&
+ new->ref_ctr_offset != tmp->ref_ctr_offset) {
+ pr_warn("Reference counter offset mismatch.");
+ return ERR_PTR(-EINVAL);
+ }
+ }
+ return old;
+}
+
/* Register a trace_uprobe and probe_event */
static int register_trace_uprobe(struct trace_uprobe *tu)
{
@@ -333,8 +362,12 @@ static int register_trace_uprobe(struct trace_uprobe *tu)
mutex_lock(&uprobe_lock);
/* register as an event */
- old_tu = find_probe_event(trace_event_name(&tu->tp.call),
- tu->tp.call.class->system);
+ old_tu = find_old_trace_uprobe(tu);
+ if (IS_ERR(old_tu)) {
+ ret = PTR_ERR(old_tu);
+ goto end;
+ }
+
if (old_tu) {
/* delete old event */
ret = unregister_trace_uprobe(old_tu);
--
2.14.4
next prev parent reply other threads:[~2018-08-09 4:19 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-09 4:18 [PATCH v8 0/6] Uprobes: Support SDT markers having reference count (semaphore) Ravi Bangoria
2018-08-09 4:18 ` [PATCH v8 1/6] Uprobes: Simplify uprobe_register() body Ravi Bangoria
2018-08-11 8:00 ` Song Liu
2018-08-13 8:56 ` Srikar Dronamraju
2018-08-14 0:07 ` Steven Rostedt
2018-08-09 4:18 ` [PATCH v8 2/6] Uprobe: Additional argument arch_uprobe to uprobe_write_opcode() Ravi Bangoria
2018-08-11 8:01 ` Song Liu
2018-08-13 8:51 ` Srikar Dronamraju
2018-08-09 4:18 ` [PATCH v8 3/6] Uprobes: Support SDT markers having reference count (semaphore) Ravi Bangoria
2018-08-09 14:38 ` Oleg Nesterov
2018-08-10 19:58 ` Steven Rostedt
2018-08-11 6:14 ` Song Liu
2018-08-14 0:01 ` Steven Rostedt
2018-08-14 0:05 ` Steven Rostedt
2018-08-11 7:57 ` Song Liu
2018-08-11 15:37 ` Steven Rostedt
2018-08-13 5:47 ` Ravi Bangoria
2018-08-13 7:38 ` Ravi Bangoria
2018-08-13 11:50 ` Oleg Nesterov
2018-08-13 13:01 ` Ravi Bangoria
2018-08-13 13:17 ` Oleg Nesterov
2018-08-13 14:26 ` Ravi Bangoria
2018-08-13 14:51 ` Oleg Nesterov
2018-08-13 17:12 ` Song Liu
2018-08-14 4:37 ` Ravi Bangoria
2018-08-14 16:35 ` Song Liu
2018-08-14 0:03 ` Steven Rostedt
2018-08-13 16:50 ` Song Liu
2018-08-13 10:03 ` Srikar Dronamraju
2018-08-13 11:23 ` Oleg Nesterov
2018-08-14 8:56 ` Ravi Bangoria
2018-08-09 4:18 ` [PATCH v8 4/6] Uprobes/sdt: Prevent multiple reference counter for same uprobe Ravi Bangoria
2018-08-11 8:04 ` Song Liu
2018-08-13 8:50 ` Srikar Dronamraju
2018-08-09 4:18 ` Ravi Bangoria [this message]
2018-08-11 8:12 ` [PATCH v8 5/6] trace_uprobe/sdt: " Song Liu
2018-08-13 8:19 ` Ravi Bangoria
2018-08-13 8:49 ` Srikar Dronamraju
2018-08-13 16:27 ` Song Liu
2018-08-13 8:48 ` Srikar Dronamraju
2018-08-09 4:18 ` [PATCH v8 6/6] perf probe: Support SDT markers having reference counter (semaphore) Ravi Bangoria
2018-08-13 16:55 ` [PATCH v8 0/6] Uprobes: Support SDT markers having reference count (semaphore) Oleg Nesterov
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