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Message-Id: <1440713521-5906-50-git-send-email-kamal@canonical.com>
Date: Thu, 27 Aug 2015 15:10:40 -0700
From: Kamal Mostafa <kamal@...onical.com>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
kernel-team@...ts.ubuntu.com
Cc: Steven Rostedt <rostedt@...dmis.org>,
Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 049/130] ftrace: Fix breakage of set_ftrace_pid
3.19.8-ckt6 -stable review patch. If anyone has any objections, please let me know.
------------------
From: "Steven Rostedt (Red Hat)" <rostedt@...dmis.org>
commit e3eea1404f5ff7a2ceb7b5e7ba412a6fd94f2935 upstream.
Commit 4104d326b670 ("ftrace: Remove global function list and call function
directly") simplified the ftrace code by removing the global_ops list with a
new design. But this cleanup also broke the filtering of PIDs that are added
to the set_ftrace_pid file.
Add back the proper hooks to have pid filtering working once again.
Reported-by: Matt Fleming <matt@...sole-pimps.org>
Reported-by: Richard Weinberger <richard.weinberger@...il.com>
Tested-by: Matt Fleming <matt@...sole-pimps.org>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
include/linux/ftrace.h | 3 +++
kernel/trace/ftrace.c | 52 +++++++++++++++++++++++++++++++++-----------------
2 files changed, 37 insertions(+), 18 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 1da6029..6cd8c0e 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -116,6 +116,7 @@ ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops);
* SAVE_REGS. If another ops with this flag set is already registered
* for any of the functions that this ops will be registered for, then
* this ops will fail to register or set_filter_ip.
+ * PID - Is affected by set_ftrace_pid (allows filtering on those pids)
*/
enum {
FTRACE_OPS_FL_ENABLED = 1 << 0,
@@ -132,6 +133,7 @@ enum {
FTRACE_OPS_FL_MODIFYING = 1 << 11,
FTRACE_OPS_FL_ALLOC_TRAMP = 1 << 12,
FTRACE_OPS_FL_IPMODIFY = 1 << 13,
+ FTRACE_OPS_FL_PID = 1 << 14,
};
#ifdef CONFIG_DYNAMIC_FTRACE
@@ -159,6 +161,7 @@ struct ftrace_ops {
struct ftrace_ops *next;
unsigned long flags;
void *private;
+ ftrace_func_t saved_func;
int __percpu *disabled;
#ifdef CONFIG_DYNAMIC_FTRACE
int nr_trampolines;
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index af5bffd..ac9516c 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -98,6 +98,13 @@ struct ftrace_pid {
struct pid *pid;
};
+static bool ftrace_pids_enabled(void)
+{
+ return !list_empty(&ftrace_pids);
+}
+
+static void ftrace_update_trampoline(struct ftrace_ops *ops);
+
/*
* ftrace_disabled is set when an anomaly is discovered.
* ftrace_disabled is much stronger than ftrace_enabled.
@@ -109,7 +116,6 @@ static DEFINE_MUTEX(ftrace_lock);
static struct ftrace_ops *ftrace_control_list __read_mostly = &ftrace_list_end;
static struct ftrace_ops *ftrace_ops_list __read_mostly = &ftrace_list_end;
ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
-ftrace_func_t ftrace_pid_function __read_mostly = ftrace_stub;
static struct ftrace_ops global_ops;
static struct ftrace_ops control_ops;
@@ -183,14 +189,7 @@ static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip,
if (!test_tsk_trace_trace(current))
return;
- ftrace_pid_function(ip, parent_ip, op, regs);
-}
-
-static void set_ftrace_pid_function(ftrace_func_t func)
-{
- /* do not set ftrace_pid_function to itself! */
- if (func != ftrace_pid_func)
- ftrace_pid_function = func;
+ op->saved_func(ip, parent_ip, op, regs);
}
/**
@@ -202,7 +201,6 @@ static void set_ftrace_pid_function(ftrace_func_t func)
void clear_ftrace_function(void)
{
ftrace_trace_function = ftrace_stub;
- ftrace_pid_function = ftrace_stub;
}
static void control_ops_disable_all(struct ftrace_ops *ops)
@@ -423,6 +421,12 @@ static int __register_ftrace_function(struct ftrace_ops *ops)
} else
add_ftrace_ops(&ftrace_ops_list, ops);
+ /* Always save the function, and reset at unregistering */
+ ops->saved_func = ops->func;
+
+ if (ops->flags & FTRACE_OPS_FL_PID && ftrace_pids_enabled())
+ ops->func = ftrace_pid_func;
+
ftrace_update_trampoline(ops);
if (ftrace_enabled)
@@ -450,15 +454,28 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
if (ftrace_enabled)
update_ftrace_function();
+ ops->func = ops->saved_func;
+
return 0;
}
static void ftrace_update_pid_func(void)
{
+ bool enabled = ftrace_pids_enabled();
+ struct ftrace_ops *op;
+
/* Only do something if we are tracing something */
if (ftrace_trace_function == ftrace_stub)
return;
+ do_for_each_ftrace_op(op, ftrace_ops_list) {
+ if (op->flags & FTRACE_OPS_FL_PID) {
+ op->func = enabled ? ftrace_pid_func :
+ op->saved_func;
+ ftrace_update_trampoline(op);
+ }
+ } while_for_each_ftrace_op(op);
+
update_ftrace_function();
}
@@ -1120,7 +1137,8 @@ static struct ftrace_ops global_ops = {
.local_hash.filter_hash = EMPTY_HASH,
INIT_OPS_HASH(global_ops)
.flags = FTRACE_OPS_FL_RECURSION_SAFE |
- FTRACE_OPS_FL_INITIALIZED,
+ FTRACE_OPS_FL_INITIALIZED |
+ FTRACE_OPS_FL_PID,
};
/*
@@ -5010,7 +5028,9 @@ static void ftrace_update_trampoline(struct ftrace_ops *ops)
static struct ftrace_ops global_ops = {
.func = ftrace_stub,
- .flags = FTRACE_OPS_FL_RECURSION_SAFE | FTRACE_OPS_FL_INITIALIZED,
+ .flags = FTRACE_OPS_FL_RECURSION_SAFE |
+ FTRACE_OPS_FL_INITIALIZED |
+ FTRACE_OPS_FL_PID,
};
static int __init ftrace_nodyn_init(void)
@@ -5067,11 +5087,6 @@ void ftrace_init_array_ops(struct trace_array *tr, ftrace_func_t func)
if (WARN_ON(tr->ops->func != ftrace_stub))
printk("ftrace ops had %pS for function\n",
tr->ops->func);
- /* Only the top level instance does pid tracing */
- if (!list_empty(&ftrace_pids)) {
- set_ftrace_pid_function(func);
- func = ftrace_pid_func;
- }
}
tr->ops->func = func;
tr->ops->private = tr;
@@ -5365,7 +5380,7 @@ static void *fpid_start(struct seq_file *m, loff_t *pos)
{
mutex_lock(&ftrace_lock);
- if (list_empty(&ftrace_pids) && (!*pos))
+ if (!ftrace_pids_enabled() && (!*pos))
return (void *) 1;
return seq_list_start(&ftrace_pids, *pos);
@@ -5604,6 +5619,7 @@ static struct ftrace_ops graph_ops = {
.func = ftrace_stub,
.flags = FTRACE_OPS_FL_RECURSION_SAFE |
FTRACE_OPS_FL_INITIALIZED |
+ FTRACE_OPS_FL_PID |
FTRACE_OPS_FL_STUB,
#ifdef FTRACE_GRAPH_TRAMP_ADDR
.trampoline = FTRACE_GRAPH_TRAMP_ADDR,
--
1.9.1
--
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