From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
stable@vger.kernel.org,
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Subject: [for-linus][PATCH 10/12] ftrace: Fix updating FTRACE_FL_TRAMP
Date: Tue, 01 Dec 2020 10:58:45 -0500 [thread overview]
Message-ID: <20201201160006.488267004@goodmis.org> (raw)
In-Reply-To: <20201201155835.647858317@goodmis.org>
From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
On powerpc, kprobe-direct.tc triggered FTRACE_WARN_ON() in
ftrace_get_addr_new() followed by the below message:
Bad trampoline accounting at: 000000004222522f (wake_up_process+0xc/0x20) (f0000001)
The set of steps leading to this involved:
- modprobe ftrace-direct-too
- enable_probe
- modprobe ftrace-direct
- rmmod ftrace-direct <-- trigger
The problem turned out to be that we were not updating flags in the
ftrace record properly. From the above message about the trampoline
accounting being bad, it can be seen that the ftrace record still has
FTRACE_FL_TRAMP set though ftrace-direct module is going away. This
happens because we are checking if any ftrace_ops has the
FTRACE_FL_TRAMP flag set _before_ updating the filter hash.
The fix for this is to look for any _other_ ftrace_ops that also needs
FTRACE_FL_TRAMP.
Link: https://lkml.kernel.org/r/56c113aa9c3e10c19144a36d9684c7882bf09af5.1606412433.git.naveen.n.rao@linux.vnet.ibm.com
Cc: stable@vger.kernel.org
Fixes: a124692b698b0 ("ftrace: Enable trampoline when rec count returns back to one")
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/ftrace.c | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 8185f7240095..9c1bba8cc51b 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1629,6 +1629,8 @@ static bool test_rec_ops_needs_regs(struct dyn_ftrace *rec)
static struct ftrace_ops *
ftrace_find_tramp_ops_any(struct dyn_ftrace *rec);
static struct ftrace_ops *
+ftrace_find_tramp_ops_any_other(struct dyn_ftrace *rec, struct ftrace_ops *op_exclude);
+static struct ftrace_ops *
ftrace_find_tramp_ops_next(struct dyn_ftrace *rec, struct ftrace_ops *ops);
static bool __ftrace_hash_rec_update(struct ftrace_ops *ops,
@@ -1778,7 +1780,7 @@ static bool __ftrace_hash_rec_update(struct ftrace_ops *ops,
* to it.
*/
if (ftrace_rec_count(rec) == 1 &&
- ftrace_find_tramp_ops_any(rec))
+ ftrace_find_tramp_ops_any_other(rec, ops))
rec->flags |= FTRACE_FL_TRAMP;
else
rec->flags &= ~FTRACE_FL_TRAMP;
@@ -2244,6 +2246,24 @@ ftrace_find_tramp_ops_any(struct dyn_ftrace *rec)
return NULL;
}
+static struct ftrace_ops *
+ftrace_find_tramp_ops_any_other(struct dyn_ftrace *rec, struct ftrace_ops *op_exclude)
+{
+ struct ftrace_ops *op;
+ unsigned long ip = rec->ip;
+
+ do_for_each_ftrace_op(op, ftrace_ops_list) {
+
+ if (op == op_exclude || !op->trampoline)
+ continue;
+
+ if (hash_contains_ip(ip, op->func_hash))
+ return op;
+ } while_for_each_ftrace_op(op);
+
+ return NULL;
+}
+
static struct ftrace_ops *
ftrace_find_tramp_ops_next(struct dyn_ftrace *rec,
struct ftrace_ops *op)
--
2.28.0
next prev parent reply other threads:[~2020-12-01 16:01 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-01 15:58 [for-linus][PATCH 00/12] tracing: Fixes for 5.10-rc6 Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 01/12] tools/bootconfig: Fix errno reference after printf() Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 02/12] tools/bootconfig: Fix to check the write failure correctly Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 03/12] tools/bootconfig: Align the bootconfig applied initrd image size to 4 Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 04/12] docs: bootconfig: Update file format on initrd image Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 05/12] ring-buffer: Update write stamp with the correct ts Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 06/12] ring-buffer: Set the right timestamp in the slow path of __rb_reserve_next() Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 07/12] samples/ftrace: Mark my_tramp[12]? global Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 08/12] tracing: Remove WARN_ON in start_thread() Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 09/12] tracing: Fix alignment of static buffer Steven Rostedt
2020-12-01 15:58 ` Steven Rostedt [this message]
2020-12-01 15:58 ` [for-linus][PATCH 11/12] ftrace: Fix DYNAMIC_FTRACE_WITH_DIRECT_CALLS dependency Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 12/12] ring-buffer: Always check to put back before stamp when crossing pages Steven Rostedt
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