[RFC][PATCH 00/12] kprobes/ftrace: Making ftrace usable for kprobes

[RFC][PATCH 00/12] kprobes/ftrace: Making ftrace usable for kprobes

[Steven Rostedt]

This is an RFC of patches that allow ftrace to be used directly by
kprobes.

The first set of patches modify the function tracer to:

 1) have ftrace_ops passed to all functions
 2) allow regs to be passed to all functions when requested

The first change is not required by kprobes, but is a nice feature
that people have asked for. You can now pass data to different
functions. Well, you can pass the ftrace_ops that registered the function
such that if two ftrace_ops register the same callback, the call back
can do different things depending on what registered it.

The second change adds a second mcount trampoline. That is,
if you request to have pt_regs returned, it will call a different
function that saves those registers. If nothing asks for regs, then
the old way is performed, and there's no slow down in the performance,
as not many functions would ever require regs passed to it.

If an arch supports passing of ftrace ops, it must also pass regs.
But it does not need to support passing all (or any) regs. By default
an arch can just pass NULL. If it supports full regs, then
it can allow tools like kprobes to ask for regs. Otherwise regs
is either NULL or a subset of full regs.

The second set is Masami's patches ported on top of these changes.

Note, I just got these working and they could use more comments in
the code. I plan on doing so and cleaning things up, but wanted to
get these out in the "release early, release often" mentality.

-- Steve

These patches are in git and can be found at:

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
rfc/kprobes/ftrace-v3

Head SHA1: 80a5eca4e5d019c752ba580400f656afc5d8aca6


Masami Hiramatsu (5):
      ftrace: add ftrace_set_filter_ip() for address based filter
      kprobes: cleanup to separate probe-able check
      kprobes: Move locks into appropriate functions
      kprobes: introduce ftrace based optimization
      kprobes/x86: ftrace based optimization for x86

Steven Rostedt (7):
      ftrace: Pass ftrace_ops as third parameter to function trace callback
      ftrace: Consolidate arch dependent functions with 'list' function
      ftrace: Return pt_regs to function trace callback (x86_64 only so far)
      ftrace/x86_32: Push ftrace_ops in as 3rd parameter to function tracer
      ftrace/x86: Add separate function to save regs
      ftrace/x86: Add save_regs for i386 function calls
      kprobes: Inverse taking of module_mutex with kprobe_mutex

----
 arch/x86/include/asm/ftrace.h     |   44 +++---
 arch/x86/include/asm/kprobes.h    |    1 +
 arch/x86/kernel/entry_32.S        |   56 ++++++++
 arch/x86/kernel/entry_64.S        |   73 +++++++++-
 arch/x86/kernel/ftrace.c          |   62 ++++++++-
 arch/x86/kernel/kprobes.c         |   48 +++++++
 include/linux/ftrace.h            |   89 +++++++++++-
 include/linux/kprobes.h           |   27 ++++
 kernel/kprobes.c                  |  250 +++++++++++++++++++++++----------
 kernel/trace/ftrace.c             |  273 ++++++++++++++++++++++++++-----------
 kernel/trace/trace_event_perf.c   |    3 +-
 kernel/trace/trace_events.c       |    3 +-
 kernel/trace/trace_functions.c    |   10 +-
 kernel/trace/trace_irqsoff.c      |    3 +-
 kernel/trace/trace_sched_wakeup.c |    3 +-
 kernel/trace/trace_selftest.c     |   20 ++-
 kernel/trace/trace_stack.c        |    3 +-
 17 files changed, 778 insertions(+), 190 deletions(-)

[RFC][PATCH 01/12] ftrace: Pass ftrace_ops as third parameter to function trace callback

[Steven Rostedt]

[-- Attachment #1: 0001-ftrace-Pass-ftrace_ops-as-third-parameter-to-functio.patch --]
[-- Type: text/plain, Size: 15929 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

Currently the function trace callback receives only the ip and parent_ip
of the function that it traced. It would be more powerful to also return
the ops that registered the function as well. This allows the same function
to act differently depending on what ftrace_ops registered it.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 arch/x86/include/asm/ftrace.h     |    4 ++
 arch/x86/kernel/entry_64.S        |    1 +
 include/linux/ftrace.h            |   16 +++++-
 kernel/trace/ftrace.c             |  101 +++++++++++++++++++++++++------------
 kernel/trace/trace_event_perf.c   |    3 +-
 kernel/trace/trace_events.c       |    3 +-
 kernel/trace/trace_functions.c    |    9 ++--
 kernel/trace/trace_irqsoff.c      |    3 +-
 kernel/trace/trace_sched_wakeup.c |    2 +-
 kernel/trace/trace_selftest.c     |   15 ++++--
 kernel/trace/trace_stack.c        |    2 +-
 11 files changed, 113 insertions(+), 46 deletions(-)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index b0767bc..783b107 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -32,6 +32,10 @@
 #define MCOUNT_ADDR		((long)(mcount))
 #define MCOUNT_INSN_SIZE	5 /* sizeof mcount call */
 
+#if defined(CONFIG_DYNAMIC_FTRACE) && defined(CONFIG_X86_64)
+#define ARCH_SUPPORTS_FTRACE_OPS 1
+#endif
+
 #ifndef __ASSEMBLY__
 extern void mcount(void);
 extern atomic_t modifying_ftrace_code;
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 7d65133..2b4f94c 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -79,6 +79,7 @@ ENTRY(ftrace_caller)
 
 	MCOUNT_SAVE_FRAME
 
+	leaq function_trace_op, %rdx
 	movq 0x38(%rsp), %rdi
 	movq 8(%rbp), %rsi
 	subq $MCOUNT_INSN_SIZE, %rdi
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 55e6d63..2d59641 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -18,6 +18,15 @@
 
 #include <asm/ftrace.h>
 
+/*
+ * If the arch supports passing the variable contents of
+ * function_trace_op as the third parameter back from the
+ * mcount call, then the arch should define this as 1.
+ */
+#ifndef ARCH_SUPPORTS_FTRACE_OPS
+#define ARCH_SUPPORTS_FTRACE_OPS 0
+#endif
+
 struct module;
 struct ftrace_hash;
 
@@ -29,7 +38,10 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
 		     void __user *buffer, size_t *lenp,
 		     loff_t *ppos);
 
-typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip);
+struct ftrace_ops;
+
+typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip,
+			      struct ftrace_ops *op);
 
 /*
  * FTRACE_OPS_FL_* bits denote the state of ftrace_ops struct and are
@@ -163,7 +175,7 @@ static inline int ftrace_function_local_disabled(struct ftrace_ops *ops)
 	return *this_cpu_ptr(ops->disabled);
 }
 
-extern void ftrace_stub(unsigned long a0, unsigned long a1);
+extern void ftrace_stub(unsigned long a0, unsigned long a1, struct ftrace_ops *op);
 
 #else /* !CONFIG_FUNCTION_TRACER */
 /*
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a008663..9b82242 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -64,12 +64,19 @@
 
 #define FL_GLOBAL_CONTROL_MASK (FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_CONTROL)
 
+static struct ftrace_ops ftrace_list_end __read_mostly = {
+	.func		= ftrace_stub,
+};
+
 /* ftrace_enabled is a method to turn ftrace on or off */
 int ftrace_enabled __read_mostly;
 static int last_ftrace_enabled;
 
 /* Quick disabling of function tracer. */
-int function_trace_stop;
+int function_trace_stop __read_mostly;
+
+/* Current function tracing op */
+struct ftrace_ops *function_trace_op __read_mostly = &ftrace_list_end;
 
 /* List for set_ftrace_pid's pids. */
 LIST_HEAD(ftrace_pids);
@@ -86,10 +93,6 @@ static int ftrace_disabled __read_mostly;
 
 static DEFINE_MUTEX(ftrace_lock);
 
-static struct ftrace_ops ftrace_list_end __read_mostly = {
-	.func		= ftrace_stub,
-};
-
 static struct ftrace_ops *ftrace_global_list __read_mostly = &ftrace_list_end;
 static struct ftrace_ops *ftrace_control_list __read_mostly = &ftrace_list_end;
 static struct ftrace_ops *ftrace_ops_list __read_mostly = &ftrace_list_end;
@@ -100,8 +103,14 @@ ftrace_func_t ftrace_pid_function __read_mostly = ftrace_stub;
 static struct ftrace_ops global_ops;
 static struct ftrace_ops control_ops;
 
-static void
-ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip);
+/* See comment below, where ftrace_ops_list_func is defined */
+#if ARCH_SUPPORTS_FTRACE_OPS
+static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
+				 struct ftrace_ops *op);
+#else
+static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
+#define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops)
+#endif
 
 /*
  * Traverse the ftrace_global_list, invoking all entries.  The reason that we
@@ -112,29 +121,29 @@ ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip);
  *
  * Silly Alpha and silly pointer-speculation compiler optimizations!
  */
-static void ftrace_global_list_func(unsigned long ip,
-				    unsigned long parent_ip)
+static void
+ftrace_global_list_func(unsigned long ip, unsigned long parent_ip,
+			struct ftrace_ops *op)
 {
-	struct ftrace_ops *op;
-
 	if (unlikely(trace_recursion_test(TRACE_GLOBAL_BIT)))
 		return;
 
 	trace_recursion_set(TRACE_GLOBAL_BIT);
 	op = rcu_dereference_raw(ftrace_global_list); /*see above*/
 	while (op != &ftrace_list_end) {
-		op->func(ip, parent_ip);
+		op->func(ip, parent_ip, op);
 		op = rcu_dereference_raw(op->next); /*see above*/
 	};
 	trace_recursion_clear(TRACE_GLOBAL_BIT);
 }
 
-static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip)
+static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip,
+			    struct ftrace_ops *op)
 {
 	if (!test_tsk_trace_trace(current))
 		return;
 
-	ftrace_pid_function(ip, parent_ip);
+	ftrace_pid_function(ip, parent_ip, op);
 }
 
 static void set_ftrace_pid_function(ftrace_func_t func)
@@ -163,12 +172,13 @@ void clear_ftrace_function(void)
  * For those archs that do not test ftrace_trace_stop in their
  * mcount call site, we need to do it from C.
  */
-static void ftrace_test_stop_func(unsigned long ip, unsigned long parent_ip)
+static void ftrace_test_stop_func(unsigned long ip, unsigned long parent_ip,
+				  struct ftrace_ops *op)
 {
 	if (function_trace_stop)
 		return;
 
-	__ftrace_trace_function(ip, parent_ip);
+	__ftrace_trace_function(ip, parent_ip, op);
 }
 #endif
 
@@ -230,15 +240,24 @@ static void update_ftrace_function(void)
 
 	/*
 	 * If we are at the end of the list and this ops is
-	 * not dynamic, then have the mcount trampoline call
-	 * the function directly
+	 * not dynamic and the arch supports passing ops, then have the
+	 * mcount trampoline call the function directly.
 	 */
 	if (ftrace_ops_list == &ftrace_list_end ||
 	    (ftrace_ops_list->next == &ftrace_list_end &&
-	     !(ftrace_ops_list->flags & FTRACE_OPS_FL_DYNAMIC)))
+	     !(ftrace_ops_list->flags & FTRACE_OPS_FL_DYNAMIC) &&
+	     ARCH_SUPPORTS_FTRACE_OPS)) {
+		/* Set the ftrace_ops that the arch callback uses */
+		if (ftrace_ops_list == &global_ops)
+			function_trace_op = ftrace_global_list;
+		else
+			function_trace_op = ftrace_ops_list;
 		func = ftrace_ops_list->func;
-	else
+	} else {
+		/* Just use the default ftrace_ops */
+		function_trace_op = &ftrace_list_end;
 		func = ftrace_ops_list_func;
+	}
 
 #ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
 	ftrace_trace_function = func;
@@ -773,7 +792,8 @@ ftrace_profile_alloc(struct ftrace_profile_stat *stat, unsigned long ip)
 }
 
 static void
-function_profile_call(unsigned long ip, unsigned long parent_ip)
+function_profile_call(unsigned long ip, unsigned long parent_ip,
+		      struct ftrace_ops *ops)
 {
 	struct ftrace_profile_stat *stat;
 	struct ftrace_profile *rec;
@@ -803,7 +823,7 @@ function_profile_call(unsigned long ip, unsigned long parent_ip)
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 static int profile_graph_entry(struct ftrace_graph_ent *trace)
 {
-	function_profile_call(trace->func, 0);
+	function_profile_call(trace->func, 0, NULL);
 	return 1;
 }
 
@@ -2790,8 +2810,8 @@ static int __init ftrace_mod_cmd_init(void)
 }
 device_initcall(ftrace_mod_cmd_init);
 
-static void
-function_trace_probe_call(unsigned long ip, unsigned long parent_ip)
+static void function_trace_probe_call(unsigned long ip, unsigned long parent_ip,
+				      struct ftrace_ops *op)
 {
 	struct ftrace_func_probe *entry;
 	struct hlist_head *hhd;
@@ -3942,10 +3962,9 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip)
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
 static void
-ftrace_ops_control_func(unsigned long ip, unsigned long parent_ip)
+ftrace_ops_control_func(unsigned long ip, unsigned long parent_ip,
+			struct ftrace_ops *op)
 {
-	struct ftrace_ops *op;
-
 	if (unlikely(trace_recursion_test(TRACE_CONTROL_BIT)))
 		return;
 
@@ -3959,7 +3978,7 @@ ftrace_ops_control_func(unsigned long ip, unsigned long parent_ip)
 	while (op != &ftrace_list_end) {
 		if (!ftrace_function_local_disabled(op) &&
 		    ftrace_ops_test(op, ip))
-			op->func(ip, parent_ip);
+			op->func(ip, parent_ip, op);
 
 		op = rcu_dereference_raw(op->next);
 	};
@@ -3971,8 +3990,9 @@ static struct ftrace_ops control_ops = {
 	.func = ftrace_ops_control_func,
 };
 
-static void
-ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
+static inline void
+__ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
+		       struct ftrace_ops *ignored)
 {
 	struct ftrace_ops *op;
 
@@ -3988,13 +4008,32 @@ ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
 	op = rcu_dereference_raw(ftrace_ops_list);
 	while (op != &ftrace_list_end) {
 		if (ftrace_ops_test(op, ip))
-			op->func(ip, parent_ip);
+			op->func(ip, parent_ip, op);
 		op = rcu_dereference_raw(op->next);
 	};
 	preempt_enable_notrace();
 	trace_recursion_clear(TRACE_INTERNAL_BIT);
 }
 
+/*
+ * Some archs only support passing ip and parent_ip. Even though
+ * the list function ignores the op parameter, we do not want any
+ * C side effects, where a function is called without the caller
+ * sending a third parameter.
+ */
+#if ARCH_SUPPORTS_FTRACE_OPS
+static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
+				 struct ftrace_ops *op)
+{
+	__ftrace_ops_list_func(ip, parent_ip, NULL);
+}
+#else
+static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip)
+{
+	__ftrace_ops_list_func(ip, parent_ip, NULL);
+}
+#endif
+
 static void clear_ftrace_swapper(void)
 {
 	struct task_struct *p;
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index fee3752..a872a9a 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -258,7 +258,8 @@ EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);
 
 #ifdef CONFIG_FUNCTION_TRACER
 static void
-perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip)
+perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
+			  struct ftrace_ops *ops)
 {
 	struct ftrace_entry *entry;
 	struct hlist_head *head;
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 29111da..88daa51 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1681,7 +1681,8 @@ static __init void event_trace_self_tests(void)
 static DEFINE_PER_CPU(atomic_t, ftrace_test_event_disable);
 
 static void
-function_test_events_call(unsigned long ip, unsigned long parent_ip)
+function_test_events_call(unsigned long ip, unsigned long parent_ip,
+			  struct ftrace_ops *op)
 {
 	struct ring_buffer_event *event;
 	struct ring_buffer *buffer;
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index c7b0c6a..fceb7a9 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -48,7 +48,8 @@ static void function_trace_start(struct trace_array *tr)
 }
 
 static void
-function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip)
+function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip,
+				 struct ftrace_ops *op)
 {
 	struct trace_array *tr = func_trace;
 	struct trace_array_cpu *data;
@@ -75,7 +76,8 @@ function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip)
 }
 
 static void
-function_trace_call(unsigned long ip, unsigned long parent_ip)
+function_trace_call(unsigned long ip, unsigned long parent_ip,
+		    struct ftrace_ops *op)
 {
 	struct trace_array *tr = func_trace;
 	struct trace_array_cpu *data;
@@ -106,7 +108,8 @@ function_trace_call(unsigned long ip, unsigned long parent_ip)
 }
 
 static void
-function_stack_trace_call(unsigned long ip, unsigned long parent_ip)
+function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
+			  struct ftrace_ops *op)
 {
 	struct trace_array *tr = func_trace;
 	struct trace_array_cpu *data;
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 99d20e9..2862c77 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -136,7 +136,8 @@ static int func_prolog_dec(struct trace_array *tr,
  * irqsoff uses its own tracer function to keep the overhead down:
  */
 static void
-irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip)
+irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip,
+		    struct ftrace_ops *op)
 {
 	struct trace_array *tr = irqsoff_trace;
 	struct trace_array_cpu *data;
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index ff791ea..0caf4f5 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -108,7 +108,7 @@ out_enable:
  * wakeup uses its own tracer function to keep the overhead down:
  */
 static void
-wakeup_tracer_call(unsigned long ip, unsigned long parent_ip)
+wakeup_tracer_call(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op)
 {
 	struct trace_array *tr = wakeup_trace;
 	struct trace_array_cpu *data;
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 288541f..9ae40c8 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -103,35 +103,40 @@ static inline void warn_failed_init_tracer(struct tracer *trace, int init_ret)
 
 static int trace_selftest_test_probe1_cnt;
 static void trace_selftest_test_probe1_func(unsigned long ip,
-					    unsigned long pip)
+					    unsigned long pip,
+					    struct ftrace_ops *op)
 {
 	trace_selftest_test_probe1_cnt++;
 }
 
 static int trace_selftest_test_probe2_cnt;
 static void trace_selftest_test_probe2_func(unsigned long ip,
-					    unsigned long pip)
+					    unsigned long pip,
+					    struct ftrace_ops *op)
 {
 	trace_selftest_test_probe2_cnt++;
 }
 
 static int trace_selftest_test_probe3_cnt;
 static void trace_selftest_test_probe3_func(unsigned long ip,
-					    unsigned long pip)
+					    unsigned long pip,
+					    struct ftrace_ops *op)
 {
 	trace_selftest_test_probe3_cnt++;
 }
 
 static int trace_selftest_test_global_cnt;
 static void trace_selftest_test_global_func(unsigned long ip,
-					    unsigned long pip)
+					    unsigned long pip,
+					    struct ftrace_ops *op)
 {
 	trace_selftest_test_global_cnt++;
 }
 
 static int trace_selftest_test_dyn_cnt;
 static void trace_selftest_test_dyn_func(unsigned long ip,
-					 unsigned long pip)
+					 unsigned long pip,
+					 struct ftrace_ops *op)
 {
 	trace_selftest_test_dyn_cnt++;
 }
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index d4545f4..e20006d 100644
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -111,7 +111,7 @@ static inline void check_stack(void)
 }
 
 static void
-stack_trace_call(unsigned long ip, unsigned long parent_ip)
+stack_trace_call(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op)
 {
 	int cpu;
 
-- 
1.7.10

[RFC][PATCH 02/12] ftrace: Consolidate arch dependent functions with list function

[Steven Rostedt]

[-- Attachment #1: 0002-ftrace-Consolidate-arch-dependent-functions-with-lis.patch --]
[-- Type: text/plain, Size: 5351 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

As the function tracer starts to get more features, the support for
theses features will spread out throughout the different architectures
over time. These features boil down to what each arch does in the
mcount trampoline (the ftrace_caller).

Currently there's two features that are not the same throughout the
archs.

 1) Support to stop function tracing before the callback
 2) passing of the ftrace ops

Both of these require placing an indirect function to support the
features if the mcount trampoline does not.

On a side note, for all architectures, when more than one callback
is registered to the function tracer, an intermediate 'list' function
is called by the mcount trampoline to iterate through the callbacks
that are registered.

Instead of making a separate function for each of these features,
and requiring several indirect calls, just use the single 'list' function
as the intermediate, to handle all cases. If an arch does not support
the 'stop function tracing' or the passing of ftrace ops, just force
it to use the list function that will handle the features required.

This makes the code cleaner and simpler and removes a lot of
 #ifdefs in the code.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/ftrace.h |   13 +++++++++++++
 kernel/trace/ftrace.c  |   45 ++++-----------------------------------------
 2 files changed, 17 insertions(+), 41 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 2d59641..3651fdc 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -27,6 +27,19 @@
 #define ARCH_SUPPORTS_FTRACE_OPS 0
 #endif
 
+/*
+ * If the arch's mcount caller does not support all of ftrace's
+ * features, then it must call an indirect function that
+ * does. Or at least does enough to prevent any unwelcomed side effects.
+ */
+#if !defined(CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST) || \
+	!ARCH_SUPPORTS_FTRACE_OPS
+# define FTRACE_FORCE_LIST_FUNC 1
+#else
+# define FTRACE_FORCE_LIST_FUNC 0
+#endif
+
+
 struct module;
 struct ftrace_hash;
 
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 9b82242..24654a2 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -97,8 +97,6 @@ static struct ftrace_ops *ftrace_global_list __read_mostly = &ftrace_list_end;
 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;
-static ftrace_func_t __ftrace_trace_function_delay __read_mostly = ftrace_stub;
-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;
@@ -162,26 +160,9 @@ static void set_ftrace_pid_function(ftrace_func_t func)
 void clear_ftrace_function(void)
 {
 	ftrace_trace_function = ftrace_stub;
-	__ftrace_trace_function = ftrace_stub;
-	__ftrace_trace_function_delay = ftrace_stub;
 	ftrace_pid_function = ftrace_stub;
 }
 
-#ifndef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
-/*
- * For those archs that do not test ftrace_trace_stop in their
- * mcount call site, we need to do it from C.
- */
-static void ftrace_test_stop_func(unsigned long ip, unsigned long parent_ip,
-				  struct ftrace_ops *op)
-{
-	if (function_trace_stop)
-		return;
-
-	__ftrace_trace_function(ip, parent_ip, op);
-}
-#endif
-
 static void control_ops_disable_all(struct ftrace_ops *ops)
 {
 	int cpu;
@@ -246,7 +227,7 @@ static void update_ftrace_function(void)
 	if (ftrace_ops_list == &ftrace_list_end ||
 	    (ftrace_ops_list->next == &ftrace_list_end &&
 	     !(ftrace_ops_list->flags & FTRACE_OPS_FL_DYNAMIC) &&
-	     ARCH_SUPPORTS_FTRACE_OPS)) {
+	     !FTRACE_FORCE_LIST_FUNC)) {
 		/* Set the ftrace_ops that the arch callback uses */
 		if (ftrace_ops_list == &global_ops)
 			function_trace_op = ftrace_global_list;
@@ -259,18 +240,7 @@ static void update_ftrace_function(void)
 		func = ftrace_ops_list_func;
 	}
 
-#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
 	ftrace_trace_function = func;
-#else
-#ifdef CONFIG_DYNAMIC_FTRACE
-	/* do not update till all functions have been modified */
-	__ftrace_trace_function_delay = func;
-#else
-	__ftrace_trace_function = func;
-#endif
-	ftrace_trace_function =
-		(func == ftrace_stub) ? func : ftrace_test_stop_func;
-#endif
 }
 
 static void add_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
@@ -1902,16 +1872,6 @@ static void ftrace_run_update_code(int command)
 	 */
 	arch_ftrace_update_code(command);
 
-#ifndef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
-	/*
-	 * For archs that call ftrace_test_stop_func(), we must
-	 * wait till after we update all the function callers
-	 * before we update the callback. This keeps different
-	 * ops that record different functions from corrupting
-	 * each other.
-	 */
-	__ftrace_trace_function = __ftrace_trace_function_delay;
-#endif
 	function_trace_stop--;
 
 	ret = ftrace_arch_code_modify_post_process();
@@ -3996,6 +3956,9 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
 {
 	struct ftrace_ops *op;
 
+	if (function_trace_stop)
+		return;
+
 	if (unlikely(trace_recursion_test(TRACE_INTERNAL_BIT)))
 		return;
 
-- 
1.7.10

[RFC][PATCH 03/12] ftrace: Return pt_regs to function trace callback (x86_64 only so far)

[Steven Rostedt]

[-- Attachment #1: 0003-ftrace-Return-pt_regs-to-function-trace-callback-x86.patch --]
[-- Type: text/plain, Size: 15013 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

Return as the 4th paramater to the function tracer callback the pt_regs.

So far this is only supported by x86_64. Currently only the regs that
are saved for mcount is stored. The rest of the regs are not defined.

When an arch supports passing the ftrace_ops as the third parameter,
it is also expected to pass regs (or partial regs) as the forth.

If an arch can pass full regs, then it should also define:
 ARCH_SUPPORTS_FTRACE_SAVE_REGS to 1

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 arch/x86/include/asm/ftrace.h     |   40 +++++++++++++++++++++----------------
 arch/x86/kernel/entry_64.S        |    8 ++++++--
 include/linux/ftrace.h            |    6 ++++--
 kernel/trace/ftrace.c             |   37 ++++++++++++++++++++--------------
 kernel/trace/trace_event_perf.c   |    2 +-
 kernel/trace/trace_events.c       |    2 +-
 kernel/trace/trace_functions.c    |    7 ++++---
 kernel/trace/trace_irqsoff.c      |    2 +-
 kernel/trace/trace_sched_wakeup.c |    3 ++-
 kernel/trace/trace_selftest.c     |   15 +++++++++-----
 kernel/trace/trace_stack.c        |    3 ++-
 11 files changed, 76 insertions(+), 49 deletions(-)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 783b107..1fca3c2 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -4,26 +4,31 @@
 #ifdef __ASSEMBLY__
 
 	.macro MCOUNT_SAVE_FRAME
-	/* taken from glibc */
-	subq $0x38, %rsp
-	movq %rax, (%rsp)
-	movq %rcx, 8(%rsp)
-	movq %rdx, 16(%rsp)
-	movq %rsi, 24(%rsp)
-	movq %rdi, 32(%rsp)
-	movq %r8, 40(%rsp)
-	movq %r9, 48(%rsp)
+	 /*
+	  * We add enough stack to save all regs.
+	  */
+	subq $(SS+8), %rsp
+	movq %rax, RAX(%rsp)
+	movq %rcx, RCX(%rsp)
+	movq %rdx, RDX(%rsp)
+	movq %rsi, RSI(%rsp)
+	movq %rdi, RDI(%rsp)
+	movq %r8, R8(%rsp)
+	movq %r9, R9(%rsp)
+	 /* Move RIP to its proper location */
+	movq SS+8(%rsp), %rdx
+	movq %rdx, RIP(%rsp)
 	.endm
 
 	.macro MCOUNT_RESTORE_FRAME
-	movq 48(%rsp), %r9
-	movq 40(%rsp), %r8
-	movq 32(%rsp), %rdi
-	movq 24(%rsp), %rsi
-	movq 16(%rsp), %rdx
-	movq 8(%rsp), %rcx
-	movq (%rsp), %rax
-	addq $0x38, %rsp
+	movq R9(%rsp), %r9
+	movq R8(%rsp), %r8
+	movq RDI(%rsp), %rdi
+	movq RSI(%rsp), %rsi
+	movq RDX(%rsp), %rdx
+	movq RCX(%rsp), %rcx
+	movq RAX(%rsp), %rax
+	addq $(SS+8), %rsp
 	.endm
 
 #endif
@@ -34,6 +39,7 @@
 
 #if defined(CONFIG_DYNAMIC_FTRACE) && defined(CONFIG_X86_64)
 #define ARCH_SUPPORTS_FTRACE_OPS 1
+#define ARCH_SUPPORTS_FTRACE_SAVE_REGS 1
 #endif
 
 #ifndef __ASSEMBLY__
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 2b4f94c..08854a9 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -80,7 +80,11 @@ ENTRY(ftrace_caller)
 	MCOUNT_SAVE_FRAME
 
 	leaq function_trace_op, %rdx
-	movq 0x38(%rsp), %rdi
+
+	/* regs go into 4th parameter */
+	leaq (%rsp), %rcx
+
+	movq RIP(%rsp), %rdi
 	movq 8(%rbp), %rsi
 	subq $MCOUNT_INSN_SIZE, %rdi
 
@@ -141,7 +145,7 @@ ENTRY(ftrace_graph_caller)
 	MCOUNT_SAVE_FRAME
 
 	leaq 8(%rbp), %rdi
-	movq 0x38(%rsp), %rsi
+	movq RIP(%rsp), %rsi
 	movq (%rbp), %rdx
 	subq $MCOUNT_INSN_SIZE, %rsi
 
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 3651fdc..e420288 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -10,6 +10,7 @@
 #include <linux/kallsyms.h>
 #include <linux/linkage.h>
 #include <linux/bitops.h>
+#include <linux/ptrace.h>
 #include <linux/ktime.h>
 #include <linux/sched.h>
 #include <linux/types.h>
@@ -54,7 +55,7 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
 struct ftrace_ops;
 
 typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip,
-			      struct ftrace_ops *op);
+			      struct ftrace_ops *op, struct pt_regs *regs);
 
 /*
  * FTRACE_OPS_FL_* bits denote the state of ftrace_ops struct and are
@@ -188,7 +189,8 @@ static inline int ftrace_function_local_disabled(struct ftrace_ops *ops)
 	return *this_cpu_ptr(ops->disabled);
 }
 
-extern void ftrace_stub(unsigned long a0, unsigned long a1, struct ftrace_ops *op);
+extern void ftrace_stub(unsigned long a0, unsigned long a1,
+			struct ftrace_ops *op, struct pt_regs *regs);
 
 #else /* !CONFIG_FUNCTION_TRACER */
 /*
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 24654a2..f3c4317 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -104,7 +104,7 @@ static struct ftrace_ops control_ops;
 /* See comment below, where ftrace_ops_list_func is defined */
 #if ARCH_SUPPORTS_FTRACE_OPS
 static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
-				 struct ftrace_ops *op);
+				 struct ftrace_ops *op, struct pt_regs *regs);
 #else
 static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
 #define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops)
@@ -121,7 +121,7 @@ static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
  */
 static void
 ftrace_global_list_func(unsigned long ip, unsigned long parent_ip,
-			struct ftrace_ops *op)
+			struct ftrace_ops *op, struct pt_regs *regs)
 {
 	if (unlikely(trace_recursion_test(TRACE_GLOBAL_BIT)))
 		return;
@@ -129,19 +129,19 @@ ftrace_global_list_func(unsigned long ip, unsigned long parent_ip,
 	trace_recursion_set(TRACE_GLOBAL_BIT);
 	op = rcu_dereference_raw(ftrace_global_list); /*see above*/
 	while (op != &ftrace_list_end) {
-		op->func(ip, parent_ip, op);
+		op->func(ip, parent_ip, op, regs);
 		op = rcu_dereference_raw(op->next); /*see above*/
 	};
 	trace_recursion_clear(TRACE_GLOBAL_BIT);
 }
 
 static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip,
-			    struct ftrace_ops *op)
+			    struct ftrace_ops *op, struct pt_regs *regs)
 {
 	if (!test_tsk_trace_trace(current))
 		return;
 
-	ftrace_pid_function(ip, parent_ip, op);
+	ftrace_pid_function(ip, parent_ip, op, regs);
 }
 
 static void set_ftrace_pid_function(ftrace_func_t func)
@@ -763,7 +763,7 @@ ftrace_profile_alloc(struct ftrace_profile_stat *stat, unsigned long ip)
 
 static void
 function_profile_call(unsigned long ip, unsigned long parent_ip,
-		      struct ftrace_ops *ops)
+		      struct ftrace_ops *ops, struct pt_regs *regs)
 {
 	struct ftrace_profile_stat *stat;
 	struct ftrace_profile *rec;
@@ -793,7 +793,7 @@ function_profile_call(unsigned long ip, unsigned long parent_ip,
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 static int profile_graph_entry(struct ftrace_graph_ent *trace)
 {
-	function_profile_call(trace->func, 0, NULL);
+	function_profile_call(trace->func, 0, NULL, NULL);
 	return 1;
 }
 
@@ -2771,7 +2771,7 @@ static int __init ftrace_mod_cmd_init(void)
 device_initcall(ftrace_mod_cmd_init);
 
 static void function_trace_probe_call(unsigned long ip, unsigned long parent_ip,
-				      struct ftrace_ops *op)
+				      struct ftrace_ops *op, struct pt_regs *pt_regs)
 {
 	struct ftrace_func_probe *entry;
 	struct hlist_head *hhd;
@@ -3923,7 +3923,7 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip)
 
 static void
 ftrace_ops_control_func(unsigned long ip, unsigned long parent_ip,
-			struct ftrace_ops *op)
+			struct ftrace_ops *op, struct pt_regs *regs)
 {
 	if (unlikely(trace_recursion_test(TRACE_CONTROL_BIT)))
 		return;
@@ -3938,7 +3938,7 @@ ftrace_ops_control_func(unsigned long ip, unsigned long parent_ip,
 	while (op != &ftrace_list_end) {
 		if (!ftrace_function_local_disabled(op) &&
 		    ftrace_ops_test(op, ip))
-			op->func(ip, parent_ip, op);
+			op->func(ip, parent_ip, op, regs);
 
 		op = rcu_dereference_raw(op->next);
 	};
@@ -3952,7 +3952,7 @@ static struct ftrace_ops control_ops = {
 
 static inline void
 __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
-		       struct ftrace_ops *ignored)
+		       struct ftrace_ops *ignored, struct pt_regs *regs)
 {
 	struct ftrace_ops *op;
 
@@ -3971,7 +3971,7 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
 	op = rcu_dereference_raw(ftrace_ops_list);
 	while (op != &ftrace_list_end) {
 		if (ftrace_ops_test(op, ip))
-			op->func(ip, parent_ip, op);
+			op->func(ip, parent_ip, op, regs);
 		op = rcu_dereference_raw(op->next);
 	};
 	preempt_enable_notrace();
@@ -3983,17 +3983,24 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
  * the list function ignores the op parameter, we do not want any
  * C side effects, where a function is called without the caller
  * sending a third parameter.
+ * Archs are to support both the regs and ftrace_ops at the same time.
+ * If they support ftrace_ops, it is assumed they support regs.
+ * If call backs want to use regs, they must either check for regs
+ * being NULL, or ARCH_SUPPORTS_FTRACE_SAVE_REGS.
+ * Note, ARCH_SUPPORT_SAVE_REGS expects a full regs to be saved.
+ * An architecture can pass partial regs with ftrace_ops and still
+ * set the ARCH_SUPPORT_FTARCE_OPS.
  */
 #if ARCH_SUPPORTS_FTRACE_OPS
 static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
-				 struct ftrace_ops *op)
+				 struct ftrace_ops *op, struct pt_regs *regs)
 {
-	__ftrace_ops_list_func(ip, parent_ip, NULL);
+	__ftrace_ops_list_func(ip, parent_ip, NULL, regs);
 }
 #else
 static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip)
 {
-	__ftrace_ops_list_func(ip, parent_ip, NULL);
+	__ftrace_ops_list_func(ip, parent_ip, NULL, NULL);
 }
 #endif
 
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index a872a9a..9824419 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -259,7 +259,7 @@ EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);
 #ifdef CONFIG_FUNCTION_TRACER
 static void
 perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
-			  struct ftrace_ops *ops)
+			  struct ftrace_ops *ops, struct pt_regs *pt_regs)
 {
 	struct ftrace_entry *entry;
 	struct hlist_head *head;
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 88daa51..8c66968 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1682,7 +1682,7 @@ static DEFINE_PER_CPU(atomic_t, ftrace_test_event_disable);
 
 static void
 function_test_events_call(unsigned long ip, unsigned long parent_ip,
-			  struct ftrace_ops *op)
+			  struct ftrace_ops *op, struct pt_regs *pt_regs)
 {
 	struct ring_buffer_event *event;
 	struct ring_buffer *buffer;
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index fceb7a9..5675ebd 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -49,7 +49,7 @@ static void function_trace_start(struct trace_array *tr)
 
 static void
 function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip,
-				 struct ftrace_ops *op)
+				 struct ftrace_ops *op, struct pt_regs *pt_regs)
 {
 	struct trace_array *tr = func_trace;
 	struct trace_array_cpu *data;
@@ -77,7 +77,8 @@ function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip,
 
 static void
 function_trace_call(unsigned long ip, unsigned long parent_ip,
-		    struct ftrace_ops *op)
+		    struct ftrace_ops *op, struct pt_regs *pt_regs)
+
 {
 	struct trace_array *tr = func_trace;
 	struct trace_array_cpu *data;
@@ -109,7 +110,7 @@ function_trace_call(unsigned long ip, unsigned long parent_ip,
 
 static void
 function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
-			  struct ftrace_ops *op)
+			  struct ftrace_ops *op, struct pt_regs *pt_regs)
 {
 	struct trace_array *tr = func_trace;
 	struct trace_array_cpu *data;
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 2862c77..c7a9ba9 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -137,7 +137,7 @@ static int func_prolog_dec(struct trace_array *tr,
  */
 static void
 irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip,
-		    struct ftrace_ops *op)
+		    struct ftrace_ops *op, struct pt_regs *pt_regs)
 {
 	struct trace_array *tr = irqsoff_trace;
 	struct trace_array_cpu *data;
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 0caf4f5..7547e36 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -108,7 +108,8 @@ out_enable:
  * wakeup uses its own tracer function to keep the overhead down:
  */
 static void
-wakeup_tracer_call(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op)
+wakeup_tracer_call(unsigned long ip, unsigned long parent_ip,
+		   struct ftrace_ops *op, struct pt_regs *pt_regs)
 {
 	struct trace_array *tr = wakeup_trace;
 	struct trace_array_cpu *data;
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 9ae40c8..add37e0 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -104,7 +104,8 @@ static inline void warn_failed_init_tracer(struct tracer *trace, int init_ret)
 static int trace_selftest_test_probe1_cnt;
 static void trace_selftest_test_probe1_func(unsigned long ip,
 					    unsigned long pip,
-					    struct ftrace_ops *op)
+					    struct ftrace_ops *op,
+					    struct pt_regs *pt_regs)
 {
 	trace_selftest_test_probe1_cnt++;
 }
@@ -112,7 +113,8 @@ static void trace_selftest_test_probe1_func(unsigned long ip,
 static int trace_selftest_test_probe2_cnt;
 static void trace_selftest_test_probe2_func(unsigned long ip,
 					    unsigned long pip,
-					    struct ftrace_ops *op)
+					    struct ftrace_ops *op,
+					    struct pt_regs *pt_regs)
 {
 	trace_selftest_test_probe2_cnt++;
 }
@@ -120,7 +122,8 @@ static void trace_selftest_test_probe2_func(unsigned long ip,
 static int trace_selftest_test_probe3_cnt;
 static void trace_selftest_test_probe3_func(unsigned long ip,
 					    unsigned long pip,
-					    struct ftrace_ops *op)
+					    struct ftrace_ops *op,
+					    struct pt_regs *pt_regs)
 {
 	trace_selftest_test_probe3_cnt++;
 }
@@ -128,7 +131,8 @@ static void trace_selftest_test_probe3_func(unsigned long ip,
 static int trace_selftest_test_global_cnt;
 static void trace_selftest_test_global_func(unsigned long ip,
 					    unsigned long pip,
-					    struct ftrace_ops *op)
+					    struct ftrace_ops *op,
+					    struct pt_regs *pt_regs)
 {
 	trace_selftest_test_global_cnt++;
 }
@@ -136,7 +140,8 @@ static void trace_selftest_test_global_func(unsigned long ip,
 static int trace_selftest_test_dyn_cnt;
 static void trace_selftest_test_dyn_func(unsigned long ip,
 					 unsigned long pip,
-					 struct ftrace_ops *op)
+					 struct ftrace_ops *op,
+					 struct pt_regs *pt_regs)
 {
 	trace_selftest_test_dyn_cnt++;
 }
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index e20006d..2fa5328 100644
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -111,7 +111,8 @@ static inline void check_stack(void)
 }
 
 static void
-stack_trace_call(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op)
+stack_trace_call(unsigned long ip, unsigned long parent_ip,
+		 struct ftrace_ops *op, struct pt_regs *pt_regs)
 {
 	int cpu;
 
-- 
1.7.10

[RFC][PATCH 04/12] ftrace/x86_32: Push ftrace_ops in as 3rd parameter to function tracer

[Steven Rostedt]

[-- Attachment #1: 0004-ftrace-x86_32-Push-ftrace_ops-in-as-3rd-parameter-to.patch --]
[-- Type: text/plain, Size: 1198 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

Add support of passing the current ftrace_ops into the 3rd parameter
of the callback to the function tracer.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 arch/x86/include/asm/ftrace.h |    3 +--
 arch/x86/kernel/entry_32.S    |    1 +
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 1fca3c2..aefea5b 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -37,9 +37,8 @@
 #define MCOUNT_ADDR		((long)(mcount))
 #define MCOUNT_INSN_SIZE	5 /* sizeof mcount call */
 
-#if defined(CONFIG_DYNAMIC_FTRACE) && defined(CONFIG_X86_64)
+#ifdef CONFIG_DYNAMIC_FTRACE
 #define ARCH_SUPPORTS_FTRACE_OPS 1
-#define ARCH_SUPPORTS_FTRACE_SAVE_REGS 1
 #endif
 
 #ifndef __ASSEMBLY__
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 01ccf9b..189c93f 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1104,6 +1104,7 @@ ENTRY(ftrace_caller)
 	pushl %edx
 	movl 0xc(%esp), %eax
 	movl 0x4(%ebp), %edx
+	leal function_trace_op, %ecx
 	subl $MCOUNT_INSN_SIZE, %eax
 
 .globl ftrace_call
-- 
1.7.10

[RFC][PATCH 05/12] ftrace/x86: Add separate function to save regs

[Steven Rostedt]

[-- Attachment #1: 0005-ftrace-x86-Add-separate-function-to-save-regs.patch --]
[-- Type: text/plain, Size: 15838 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

Add a way to have different functions calling different trampolines.
If a ftrace_ops wants regs saved on the return, then have only the
functions with ops registered to save regs. Functions registered by
other ops would not be affected, unless the functions overlap.

If one ftrace_ops registered functions A, B and C and another ops
registered fucntions to save regs on A, and D, then only functions
A and D would be saving regs. Function B and C would work as normal.
Although A is registered by both ops: normal and saves regs; this is fine
as saving the regs is needed to satisfy one of the ops that calls it
but the regs are ignored by the other ops function.

x86_64 implements the full regs saving, and i386 just passes a NULL
for regs to satisfy the ftrace_ops passing. Where an arch must supply
both regs and ftrace_ops parameters, even if regs is just NULL.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 arch/x86/include/asm/ftrace.h |    3 ++
 arch/x86/kernel/entry_32.S    |    2 ++
 arch/x86/kernel/entry_64.S    |   64 +++++++++++++++++++++++++++++++++++++-
 arch/x86/kernel/ftrace.c      |   66 ++++++++++++++++++++++++++++++++++++---
 include/linux/ftrace.h        |   55 ++++++++++++++++++++++++++++++--
 kernel/trace/ftrace.c         |   69 ++++++++++++++++++++++++++++++++++++-----
 6 files changed, 244 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index aefea5b..71eeef6 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -39,6 +39,9 @@
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 #define ARCH_SUPPORTS_FTRACE_OPS 1
+#ifdef CONFIG_X86_64
+#define ARCH_SUPPORTS_FTRACE_SAVE_REGS
+#endif
 #endif
 
 #ifndef __ASSEMBLY__
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 189c93f..4f9895f 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1102,6 +1102,7 @@ ENTRY(ftrace_caller)
 	pushl %eax
 	pushl %ecx
 	pushl %edx
+	pushl $0	/* Pass NULL as regs pointer */
 	movl 0xc(%esp), %eax
 	movl 0x4(%ebp), %edx
 	leal function_trace_op, %ecx
@@ -1111,6 +1112,7 @@ ENTRY(ftrace_caller)
 ftrace_call:
 	call ftrace_stub
 
+	addl $4,%esp	/* skip NULL pointer */
 	popl %edx
 	popl %ecx
 	popl %eax
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 08854a9..096dbe2 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -73,24 +73,50 @@ ENTRY(mcount)
 	retq
 END(mcount)
 
-ENTRY(ftrace_caller)
+/*
+ * Breakup the ftrace_caller setup into two parts.
+ *
+ * The first part tests function_trace_stop to see
+ * if function tracing is stopped. Then it saves the
+ * regs for calling a function, and loads the ftrace_ops
+ * into the rdx register (third parameter).
+ *
+ * The second part saves the pt_regs (stack) into rcx
+ * (forth parameter), and puts the ip and parent ip into
+ * rdi and rsi (first and second parameters respectively).
+ *
+ * The reason for the two part setup is to do the same thing
+ * for both the normal ftrace_caller and the ftrace_regs_caller.
+ * The difference is that the ftrace_regs_caller will also save
+ * the rest of the stack frame into pt_regs for the called
+ * function to have a full pt_regs setup.
+ */
+.macro ftrace_caller_setup1
 	cmpl $0, function_trace_stop
 	jne  ftrace_stub
 
 	MCOUNT_SAVE_FRAME
 
 	leaq function_trace_op, %rdx
+.endm
 
+.macro ftrace_caller_setup2
 	/* regs go into 4th parameter */
 	leaq (%rsp), %rcx
 
 	movq RIP(%rsp), %rdi
 	movq 8(%rbp), %rsi
 	subq $MCOUNT_INSN_SIZE, %rdi
+.endm
+
+ENTRY(ftrace_caller)
+	ftrace_caller_setup1
+	ftrace_caller_setup2
 
 GLOBAL(ftrace_call)
 	call ftrace_stub
 
+ftrace_restore:
 	MCOUNT_RESTORE_FRAME
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
@@ -102,6 +128,42 @@ GLOBAL(ftrace_stub)
 	retq
 END(ftrace_caller)
 
+ENTRY(ftrace_regs_caller)
+	ftrace_caller_setup1
+
+	/* Save the rest of pt_regs */
+	movq %r15, R15(%rsp)
+	movq %r14, R14(%rsp)
+	movq %r13, R13(%rsp)
+	movq %r12, R12(%rsp)
+	movq %r10, R10(%rsp)
+	movq %rbp, RBP(%rsp)
+	movq %rbx, RBX(%rsp)
+	/* add flags to stack */
+	pushfq
+	/* rcx gets clobbered by the finish routine anyway */
+	movq 0(%rsp), %rcx
+	addq $8, %rsp
+	movq %rcx, EFLAGS(%rsp)
+
+	ftrace_caller_setup2
+
+GLOBAL(ftrace_regs_call)
+	call ftrace_stub
+
+	/* restore the rest of pt_regs */
+	movq R15(%rsp), %r15
+	movq R14(%rsp), %r14
+	movq R13(%rsp), %r13
+	movq R12(%rsp), %r12
+	movq R10(%rsp), %r10
+	movq RBP(%rsp), %rbp
+	movq RBX(%rsp), %rbx
+
+	jmp ftrace_restore
+END(ftrace_regs_caller)
+
+
 #else /* ! CONFIG_DYNAMIC_FTRACE */
 ENTRY(mcount)
 	cmpl $0, function_trace_stop
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index c3a7cb4..54cfc66 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -206,6 +206,22 @@ static int
 ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
 		   unsigned const char *new_code);
 
+#ifdef ARCH_SUPPORTS_FTRACE_SAVE_REGS
+/* Should never be called */
+int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
+				 unsigned long addr)
+{
+	unsigned const char *new, *old;
+	unsigned long ip = rec->ip;
+
+	return -EINVAL;
+	old = ftrace_call_replace(ip, old_addr);
+	new = ftrace_call_replace(ip, addr);
+
+	return ftrace_modify_code(rec->ip, old, new);
+}
+#endif
+
 int ftrace_update_ftrace_func(ftrace_func_t func)
 {
 	unsigned long ip = (unsigned long)(&ftrace_call);
@@ -220,6 +236,16 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 
 	ret = ftrace_modify_code(ip, old, new);
 
+#ifdef ARCH_SUPPORTS_FTRACE_SAVE_REGS
+	/* Also update the regs version */
+	if (!ret) {
+		ip = (unsigned long)(&ftrace_regs_call);
+		memcpy(old, &ftrace_regs_call, MCOUNT_INSN_SIZE);
+		new = ftrace_call_replace(ip, (unsigned long)func);
+		ret = ftrace_modify_code(ip, old, new);
+	}
+#endif
+
 	atomic_dec(&modifying_ftrace_code);
 
 	return ret;
@@ -299,6 +325,22 @@ static int add_brk_on_nop(struct dyn_ftrace *rec)
 	return add_break(rec->ip, old);
 }
 
+static unsigned long get_ftrace_addr(struct dyn_ftrace *rec)
+{
+	if (rec->flags & FTRACE_FL_REGS)
+		return (unsigned long)FTRACE_REGS_ADDR;
+	else
+		return (unsigned long)FTRACE_ADDR;
+}
+
+static unsigned long get_ftrace_old_addr(struct dyn_ftrace *rec)
+{
+	if (rec->flags & FTRACE_FL_REGS_EN)
+		return (unsigned long)FTRACE_REGS_ADDR;
+	else
+		return (unsigned long)FTRACE_ADDR;
+}
+
 static int add_breakpoints(struct dyn_ftrace *rec, int enable)
 {
 	unsigned long ftrace_addr;
@@ -306,7 +348,7 @@ static int add_breakpoints(struct dyn_ftrace *rec, int enable)
 
 	ret = ftrace_test_record(rec, enable);
 
-	ftrace_addr = (unsigned long)FTRACE_ADDR;
+	ftrace_addr = get_ftrace_addr(rec);
 
 	switch (ret) {
 	case FTRACE_UPDATE_IGNORE:
@@ -316,6 +358,10 @@ static int add_breakpoints(struct dyn_ftrace *rec, int enable)
 		/* converting nop to call */
 		return add_brk_on_nop(rec);
 
+	case FTRACE_UPDATE_MODIFY_CALL_REGS:
+	case FTRACE_UPDATE_MODIFY_CALL:
+		ftrace_addr = get_ftrace_old_addr(rec);
+		/* fall through */
 	case FTRACE_UPDATE_MAKE_NOP:
 		/* converting a call to a nop */
 		return add_brk_on_call(rec, ftrace_addr);
@@ -360,13 +406,21 @@ static int remove_breakpoint(struct dyn_ftrace *rec)
 		 * If not, don't touch the breakpoint, we make just create
 		 * a disaster.
 		 */
-		ftrace_addr = (unsigned long)FTRACE_ADDR;
+		ftrace_addr = get_ftrace_addr(rec);
+		nop = ftrace_call_replace(ip, ftrace_addr);
+
+		if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) == 0)
+			goto update;
+
+		/* Check both ftrace_addr and ftrace_old_addr */
+		ftrace_addr = get_ftrace_old_addr(rec);
 		nop = ftrace_call_replace(ip, ftrace_addr);
 
 		if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0)
 			return -EINVAL;
 	}
 
+ update:
 	return probe_kernel_write((void *)ip, &nop[0], 1);
 }
 
@@ -405,12 +459,14 @@ static int add_update(struct dyn_ftrace *rec, int enable)
 
 	ret = ftrace_test_record(rec, enable);
 
-	ftrace_addr = (unsigned long)FTRACE_ADDR;
+	ftrace_addr  = get_ftrace_addr(rec);
 
 	switch (ret) {
 	case FTRACE_UPDATE_IGNORE:
 		return 0;
 
+	case FTRACE_UPDATE_MODIFY_CALL_REGS:
+	case FTRACE_UPDATE_MODIFY_CALL:
 	case FTRACE_UPDATE_MAKE_CALL:
 		/* converting nop to call */
 		return add_update_call(rec, ftrace_addr);
@@ -455,12 +511,14 @@ static int finish_update(struct dyn_ftrace *rec, int enable)
 
 	ret = ftrace_update_record(rec, enable);
 
-	ftrace_addr = (unsigned long)FTRACE_ADDR;
+	ftrace_addr = get_ftrace_addr(rec);
 
 	switch (ret) {
 	case FTRACE_UPDATE_IGNORE:
 		return 0;
 
+	case FTRACE_UPDATE_MODIFY_CALL_REGS:
+	case FTRACE_UPDATE_MODIFY_CALL:
 	case FTRACE_UPDATE_MAKE_CALL:
 		/* converting nop to call */
 		return finish_update_call(rec, ftrace_addr);
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index e420288..67c0b73 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -77,6 +77,7 @@ enum {
 	FTRACE_OPS_FL_GLOBAL		= 1 << 1,
 	FTRACE_OPS_FL_DYNAMIC		= 1 << 2,
 	FTRACE_OPS_FL_CONTROL		= 1 << 3,
+	FTRACE_OPS_FL_SAVE_REGS		= 1 << 4,
 };
 
 struct ftrace_ops {
@@ -255,11 +256,13 @@ extern void unregister_ftrace_function_probe_all(char *glob);
 extern int ftrace_text_reserved(void *start, void *end);
 
 enum {
-	FTRACE_FL_ENABLED	= (1 << 30),
+	FTRACE_FL_ENABLED	= (1UL << 29),
+	FTRACE_FL_REGS		= (1UL << 30),
+	FTRACE_FL_REGS_EN	= (1UL << 31)
 };
 
-#define FTRACE_FL_MASK		(0x3UL << 30)
-#define FTRACE_REF_MAX		((1 << 30) - 1)
+#define FTRACE_FL_MASK		(0x7UL << 29)
+#define FTRACE_REF_MAX		((1UL << 29) - 1)
 
 struct dyn_ftrace {
 	union {
@@ -293,6 +296,8 @@ enum {
 enum {
 	FTRACE_UPDATE_IGNORE,
 	FTRACE_UPDATE_MAKE_CALL,
+	FTRACE_UPDATE_MODIFY_CALL,
+	FTRACE_UPDATE_MODIFY_CALL_REGS,
 	FTRACE_UPDATE_MAKE_NOP,
 };
 
@@ -344,7 +349,9 @@ extern int ftrace_dyn_arch_init(void *data);
 extern void ftrace_replace_code(int enable);
 extern int ftrace_update_ftrace_func(ftrace_func_t func);
 extern void ftrace_caller(void);
+extern void ftrace_regs_caller(void);
 extern void ftrace_call(void);
+extern void ftrace_regs_call(void);
 extern void mcount_call(void);
 
 void ftrace_modify_all_code(int command);
@@ -352,6 +359,15 @@ void ftrace_modify_all_code(int command);
 #ifndef FTRACE_ADDR
 #define FTRACE_ADDR ((unsigned long)ftrace_caller)
 #endif
+
+#ifndef FTRACE_REGS_ADDR
+#ifdef ARCH_SUPPORTS_FTRACE_SAVE_REGS
+# define FTRACE_REGS_ADDR ((unsigned long)ftrace_regs_caller)
+#else
+# define FTRACE_REGS_ADDR ((unsigned long)ftrace_caller)
+#endif
+#endif
+
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 extern void ftrace_graph_caller(void);
 extern int ftrace_enable_ftrace_graph_caller(void);
@@ -407,6 +423,39 @@ extern int ftrace_make_nop(struct module *mod,
  */
 extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr);
 
+#ifdef ARCH_SUPPORTS_FTRACE_SAVE_REGS
+/**
+ * ftrace_modify_call - convert from one addr to another (no nop)
+ * @rec: the mcount call site record
+ * @old_addr: the address expected to be currently called to
+ * @addr: the address to change to
+ *
+ * This is a very sensitive operation and great care needs
+ * to be taken by the arch.  The operation should carefully
+ * read the location, check to see if what is read is indeed
+ * what we expect it to be, and then on success of the compare,
+ * it should write to the location.
+ *
+ * The code segment at @rec->ip should be a caller to @old_addr
+ *
+ * Return must be:
+ *  0 on success
+ *  -EFAULT on error reading the location
+ *  -EINVAL on a failed compare of the contents
+ *  -EPERM  on error writing to the location
+ * Any other value will be considered a failure.
+ */
+extern int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
+			      unsigned long addr);
+#else
+/* Should never be called */
+static inline int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
+				     unsigned long addr)
+{
+	return -EINVAL;
+}
+#endif
+
 /* May be defined in arch */
 extern int ftrace_arch_read_dyn_info(char *buf, int size);
 
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f3c4317..73fab15 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1515,6 +1515,12 @@ static void __ftrace_hash_rec_update(struct ftrace_ops *ops,
 			rec->flags++;
 			if (FTRACE_WARN_ON((rec->flags & ~FTRACE_FL_MASK) == FTRACE_REF_MAX))
 				return;
+			/*
+			 * If any ops wants regs saved for this function
+			 * then all ops will get saved regs.
+			 */
+			if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
+				rec->flags |= FTRACE_FL_REGS;
 		} else {
 			if (FTRACE_WARN_ON((rec->flags & ~FTRACE_FL_MASK) == 0))
 				return;
@@ -1606,18 +1612,53 @@ static int ftrace_check_record(struct dyn_ftrace *rec, int enable, int update)
 	if (enable && (rec->flags & ~FTRACE_FL_MASK))
 		flag = FTRACE_FL_ENABLED;
 
+	/*
+	 * If enabling and the REGS flag does not match the REGS_EN, then
+	 * do not ignore this record. Set flags to fail the compare against
+	 * ENABLED.
+	 */
+	if (flag &&
+	    (!(rec->flags & FTRACE_FL_REGS) != !(rec->flags & FTRACE_FL_REGS_EN)))
+		flag |= FTRACE_FL_REGS;
+
 	/* If the state of this record hasn't changed, then do nothing */
 	if ((rec->flags & FTRACE_FL_ENABLED) == flag)
 		return FTRACE_UPDATE_IGNORE;
 
 	if (flag) {
-		if (update)
+		/* Save off if rec is being enabled (for return value) */
+		flag ^= rec->flags & FTRACE_FL_ENABLED;
+
+		if (update) {
 			rec->flags |= FTRACE_FL_ENABLED;
-		return FTRACE_UPDATE_MAKE_CALL;
+			if (flag & FTRACE_FL_REGS) {
+				if (rec->flags & FTRACE_FL_REGS)
+					rec->flags |= FTRACE_FL_REGS_EN;
+				else
+					rec->flags &= ~FTRACE_FL_REGS_EN;
+			}
+		}
+
+		/*
+		 * If this record is being updated from a nop, then
+		 *   return UPDATE_MAKE_CALL.
+		 * Otherwise, if the EN flag is set, then return
+		 *   UPDATE_MODIFY_CALL_REGS to tell the caller to convert
+		 *   from the non-save regs, to a save regs function.
+		 * Otherwise,
+		 *   return UPDATE_MODIFY_CALL to tell the caller to convert
+		 *   from the save regs, to a save non-regs function.
+		 */
+		if (flag & FTRACE_FL_ENABLED)
+			return FTRACE_UPDATE_MAKE_CALL;
+		else if (rec->flags & FTRACE_FL_REGS_EN)
+			return FTRACE_UPDATE_MODIFY_CALL_REGS;
+		else
+			return FTRACE_UPDATE_MODIFY_CALL;
 	}
 
 	if (update)
-		rec->flags &= ~FTRACE_FL_ENABLED;
+		rec->flags &= ~FTRACE_FL_MASK; /* Clear all flags */
 
 	return FTRACE_UPDATE_MAKE_NOP;
 }
@@ -1652,13 +1693,17 @@ int ftrace_test_record(struct dyn_ftrace *rec, int enable)
 static int
 __ftrace_replace_code(struct dyn_ftrace *rec, int enable)
 {
+	unsigned long ftrace_old_addr;
 	unsigned long ftrace_addr;
 	int ret;
 
-	ftrace_addr = (unsigned long)FTRACE_ADDR;
-
 	ret = ftrace_update_record(rec, enable);
 
+	if (rec->flags & FTRACE_FL_REGS)
+		ftrace_addr = (unsigned long)FTRACE_REGS_ADDR;
+	else
+		ftrace_addr = (unsigned long)FTRACE_ADDR;
+
 	switch (ret) {
 	case FTRACE_UPDATE_IGNORE:
 		return 0;
@@ -1668,6 +1713,15 @@ __ftrace_replace_code(struct dyn_ftrace *rec, int enable)
 
 	case FTRACE_UPDATE_MAKE_NOP:
 		return ftrace_make_nop(NULL, rec, ftrace_addr);
+
+	case FTRACE_UPDATE_MODIFY_CALL_REGS:
+	case FTRACE_UPDATE_MODIFY_CALL:
+		if (rec->flags & FTRACE_FL_REGS)
+			ftrace_old_addr = (unsigned long)FTRACE_ADDR;
+		else
+			ftrace_old_addr = (unsigned long)FTRACE_REGS_ADDR;
+
+		return ftrace_modify_call(rec, ftrace_old_addr, ftrace_addr);
 	}
 
 	return -1; /* unknow ftrace bug */
@@ -2421,8 +2475,9 @@ static int t_show(struct seq_file *m, void *v)
 
 	seq_printf(m, "%ps", (void *)rec->ip);
 	if (iter->flags & FTRACE_ITER_ENABLED)
-		seq_printf(m, " (%ld)",
-			   rec->flags & ~FTRACE_FL_MASK);
+		seq_printf(m, " (%ld)%s",
+			   rec->flags & ~FTRACE_FL_MASK,
+			   rec->flags & FTRACE_FL_REGS ? " R" : "");
 	seq_printf(m, "\n");
 
 	return 0;
-- 
1.7.10

[RFC][PATCH 06/12] ftrace/x86: Add save_regs for i386 function calls

[Steven Rostedt]

[-- Attachment #1: 0006-ftrace-x86-Add-save_regs-for-i386-function-calls.patch --]
[-- Type: text/plain, Size: 3604 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

Add saving full regs for function tracing on i386.
The saving of regs was influenced by patches sent out by
Masami Hiramatsu.

Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 arch/x86/include/asm/ftrace.h |    2 --
 arch/x86/kernel/entry_32.S    |   53 +++++++++++++++++++++++++++++++++++++++++
 arch/x86/kernel/ftrace.c      |    4 ----
 3 files changed, 53 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 71eeef6..fd34c43 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -39,10 +39,8 @@
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 #define ARCH_SUPPORTS_FTRACE_OPS 1
-#ifdef CONFIG_X86_64
 #define ARCH_SUPPORTS_FTRACE_SAVE_REGS
 #endif
-#endif
 
 #ifndef __ASSEMBLY__
 extern void mcount(void);
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 4f9895f..c54d5db 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1116,6 +1116,7 @@ ftrace_call:
 	popl %edx
 	popl %ecx
 	popl %eax
+ftrace_ret:
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 .globl ftrace_graph_call
 ftrace_graph_call:
@@ -1127,6 +1128,58 @@ ftrace_stub:
 	ret
 END(ftrace_caller)
 
+ENTRY(ftrace_regs_caller)
+	pushf	/* push flags before compare */
+	cmpl $0, function_trace_stop
+	jne ftrace_exit
+
+	subl $8, %esp	/* skip ip and orig_ax */
+	pushl %gs
+	pushl %fs
+	pushl %es
+	pushl %ds
+	pushl %eax
+	pushl %ebp
+	pushl %edi
+	pushl %esi
+	pushl %edx
+	pushl %ecx
+	pushl %ebx
+	movl 14*4(%esp), %eax	/* Load return address */
+	pushl %eax		/* Save return address (+4) */
+	subl $MCOUNT_INSN_SIZE, %eax
+	movl %eax, 12*4+4(%esp)	/* Store IP */
+	movl 13*4+4(%esp), %edx	/* Load flags */
+	movl %edx, 14*4+4(%esp)	/* Store flags */
+	movl $__KERNEL_CS, %edx
+	movl %edx, 13*4+4(%esp)	/* Store CS */
+
+	movl 0x4(%ebp), %edx
+	lea  4(%esp), %ecx
+	pushl %ecx		/* Save pt_regs as 4th parameter */
+	leal function_trace_op, %ecx
+
+GLOBAL(ftrace_regs_call)
+	call ftrace_stub
+
+	addl $4,%esp		/* Skip pt_regs */
+	popl %eax
+	movl %eax, 14*4(%esp)	/* Restore return address */
+	popl %ebx
+	popl %ecx
+	popl %edx
+	popl %esi
+	popl %edi
+	popl %ebp
+	popl %eax
+	popl %ds
+	popl %es
+	popl %fs
+	popl %gs
+	addl $8, %esp
+ftrace_exit:
+	addl $4, %esp		/* Skip eflags */
+	jmp ftrace_ret
 #else /* ! CONFIG_DYNAMIC_FTRACE */
 
 ENTRY(mcount)
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 54cfc66..cf4de56 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -206,7 +206,6 @@ static int
 ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
 		   unsigned const char *new_code);
 
-#ifdef ARCH_SUPPORTS_FTRACE_SAVE_REGS
 /* Should never be called */
 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 				 unsigned long addr)
@@ -220,7 +219,6 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 
 	return ftrace_modify_code(rec->ip, old, new);
 }
-#endif
 
 int ftrace_update_ftrace_func(ftrace_func_t func)
 {
@@ -236,7 +234,6 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 
 	ret = ftrace_modify_code(ip, old, new);
 
-#ifdef ARCH_SUPPORTS_FTRACE_SAVE_REGS
 	/* Also update the regs version */
 	if (!ret) {
 		ip = (unsigned long)(&ftrace_regs_call);
@@ -244,7 +241,6 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 		new = ftrace_call_replace(ip, (unsigned long)func);
 		ret = ftrace_modify_code(ip, old, new);
 	}
-#endif
 
 	atomic_dec(&modifying_ftrace_code);
 
-- 
1.7.10

[RFC][PATCH 07/12] ftrace: add ftrace_set_filter_ip() for address based filter

[Steven Rostedt]

[-- Attachment #1: 0007-ftrace-add-ftrace_set_filter_ip-for-address-based-fi.patch --]
[-- Type: text/plain, Size: 4273 bytes --]

From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

Add a new filter update interface ftrace_set_filter_ip()
to set ftrace filter by ip address, not only glob pattern.

Link: http://lkml.kernel.org/r/20120605102808.27845.67952.stgit@localhost.localdomain

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/ftrace.h |    3 +++
 kernel/trace/ftrace.c  |   59 ++++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 67c0b73..0254793 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -274,6 +274,8 @@ struct dyn_ftrace {
 };
 
 int ftrace_force_update(void);
+int ftrace_set_filter_ip(struct ftrace_ops *ops, unsigned long ip,
+			 int remove, int reset);
 int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
 		       int len, int reset);
 int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
@@ -489,6 +491,7 @@ static inline int ftrace_text_reserved(void *start, void *end)
  */
 #define ftrace_regex_open(ops, flag, inod, file) ({ -ENODEV; })
 #define ftrace_set_early_filter(ops, buf, enable) do { } while (0)
+#define ftrace_set_filter_ip(ops, ip, remove, reset) ({ -ENODEV; })
 #define ftrace_set_filter(ops, buf, len, reset) ({ -ENODEV; })
 #define ftrace_set_notrace(ops, buf, len, reset) ({ -ENODEV; })
 #define ftrace_free_filter(ops) do { } while (0)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 73fab15..269f076 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3197,8 +3197,27 @@ ftrace_notrace_write(struct file *file, const char __user *ubuf,
 }
 
 static int
-ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len,
-		 int reset, int enable)
+ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove)
+{
+	struct ftrace_func_entry *entry;
+
+	if (!ftrace_location(ip))
+		return -EINVAL;
+
+	if (remove) {
+		entry = ftrace_lookup_ip(hash, ip);
+		if (!entry)
+			return -ENOENT;
+		free_hash_entry(hash, entry);
+		return 0;
+	}
+
+	return add_hash_entry(hash, ip);
+}
+
+static int
+ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len,
+		unsigned long ip, int remove, int reset, int enable)
 {
 	struct ftrace_hash **orig_hash;
 	struct ftrace_hash *hash;
@@ -3227,6 +3246,11 @@ ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len,
 		ret = -EINVAL;
 		goto out_regex_unlock;
 	}
+	if (ip) {
+		ret = ftrace_match_addr(hash, ip, remove);
+		if (ret < 0)
+			goto out_regex_unlock;
+	}
 
 	mutex_lock(&ftrace_lock);
 	ret = ftrace_hash_move(ops, enable, orig_hash, hash);
@@ -3243,6 +3267,37 @@ ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len,
 	return ret;
 }
 
+static int
+ftrace_set_addr(struct ftrace_ops *ops, unsigned long ip, int remove,
+		int reset, int enable)
+{
+	return ftrace_set_hash(ops, 0, 0, ip, remove, reset, enable);
+}
+
+/**
+ * ftrace_set_filter_ip - set a function to filter on in ftrace by address
+ * @ops - the ops to set the filter with
+ * @ip - the address to add to or remove from the filter.
+ * @remove - non zero to remove the ip from the filter
+ * @reset - non zero to reset all filters before applying this filter.
+ *
+ * Filters denote which functions should be enabled when tracing is enabled
+ * If @ip is NULL, it failes to update filter.
+ */
+int ftrace_set_filter_ip(struct ftrace_ops *ops, unsigned long ip,
+			 int remove, int reset)
+{
+	return ftrace_set_addr(ops, ip, remove, reset, 1);
+}
+EXPORT_SYMBOL_GPL(ftrace_set_filter_ip);
+
+static int
+ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len,
+		 int reset, int enable)
+{
+	return ftrace_set_hash(ops, buf, len, 0, 0, reset, enable);
+}
+
 /**
  * ftrace_set_filter - set a function to filter on in ftrace
  * @ops - the ops to set the filter with
-- 
1.7.10

[RFC][PATCH 08/12] kprobes: Inverse taking of module_mutex with kprobe_mutex

[Steven Rostedt]

[-- Attachment #1: 0008-kprobes-Inverse-taking-of-module_mutex-with-kprobe_m.patch --]
[-- Type: text/plain, Size: 1965 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

Currently module_mutex is taken before kprobe_mutex, but this
can cause issues when we have kprobes register ftrace, as the ftrace
mutex is taken before enabling a tracepoint, which currently takes
the module mutex.

If module_mutex is taken before kprobe_mutex, then we can not
have kprobes use the ftrace infrastructure.

There seems to be no reason that the kprobe_mutex can't be taken
before the module_mutex. Running lockdep shows that it is safe
among the kernels I've run.

Link: http://lkml.kernel.org/r/20120605102814.27845.21047.stgit@localhost.localdomain

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/kprobes.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index c62b854..7a8a122 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -561,9 +561,9 @@ static __kprobes void kprobe_optimizer(struct work_struct *work)
 {
 	LIST_HEAD(free_list);
 
+	mutex_lock(&kprobe_mutex);
 	/* Lock modules while optimizing kprobes */
 	mutex_lock(&module_mutex);
-	mutex_lock(&kprobe_mutex);
 
 	/*
 	 * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
@@ -586,8 +586,8 @@ static __kprobes void kprobe_optimizer(struct work_struct *work)
 	/* Step 4: Free cleaned kprobes after quiesence period */
 	do_free_cleaned_kprobes(&free_list);
 
-	mutex_unlock(&kprobe_mutex);
 	mutex_unlock(&module_mutex);
+	mutex_unlock(&kprobe_mutex);
 
 	/* Step 5: Kick optimizer again if needed */
 	if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
-- 
1.7.10

[RFC][PATCH 09/12] kprobes: cleanup to separate probe-able check

[Steven Rostedt]

[-- Attachment #1: 0009-kprobes-cleanup-to-separate-probe-able-check.patch --]
[-- Type: text/plain, Size: 3992 bytes --]

From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

Separate probe-able address checking code from
register_kprobe().

Link: http://lkml.kernel.org/r/20120605102820.27845.90133.stgit@localhost.localdomain

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/kprobes.c |   82 ++++++++++++++++++++++++++++++------------------------
 1 file changed, 45 insertions(+), 37 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 7a8a122..6137fe3 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1313,67 +1313,80 @@ static inline int check_kprobe_rereg(struct kprobe *p)
 	return ret;
 }
 
-int __kprobes register_kprobe(struct kprobe *p)
+static __kprobes int check_kprobe_address_safe(struct kprobe *p,
+					       struct module **probed_mod)
 {
 	int ret = 0;
-	struct kprobe *old_p;
-	struct module *probed_mod;
-	kprobe_opcode_t *addr;
-
-	addr = kprobe_addr(p);
-	if (IS_ERR(addr))
-		return PTR_ERR(addr);
-	p->addr = addr;
-
-	ret = check_kprobe_rereg(p);
-	if (ret)
-		return ret;
 
 	jump_label_lock();
 	preempt_disable();
+
+	/* Ensure it is not in reserved area nor out of text */
 	if (!kernel_text_address((unsigned long) p->addr) ||
 	    in_kprobes_functions((unsigned long) p->addr) ||
 	    ftrace_text_reserved(p->addr, p->addr) ||
 	    jump_label_text_reserved(p->addr, p->addr)) {
 		ret = -EINVAL;
-		goto cannot_probe;
+		goto out;
 	}
 
-	/* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
-	p->flags &= KPROBE_FLAG_DISABLED;
-
-	/*
-	 * Check if are we probing a module.
-	 */
-	probed_mod = __module_text_address((unsigned long) p->addr);
-	if (probed_mod) {
-		/* Return -ENOENT if fail. */
-		ret = -ENOENT;
+	/* Check if are we probing a module */
+	*probed_mod = __module_text_address((unsigned long) p->addr);
+	if (*probed_mod) {
 		/*
 		 * We must hold a refcount of the probed module while updating
 		 * its code to prohibit unexpected unloading.
 		 */
-		if (unlikely(!try_module_get(probed_mod)))
-			goto cannot_probe;
+		if (unlikely(!try_module_get(*probed_mod))) {
+			ret = -ENOENT;
+			goto out;
+		}
 
 		/*
 		 * If the module freed .init.text, we couldn't insert
 		 * kprobes in there.
 		 */
-		if (within_module_init((unsigned long)p->addr, probed_mod) &&
-		    probed_mod->state != MODULE_STATE_COMING) {
-			module_put(probed_mod);
-			goto cannot_probe;
+		if (within_module_init((unsigned long)p->addr, *probed_mod) &&
+		    (*probed_mod)->state != MODULE_STATE_COMING) {
+			module_put(*probed_mod);
+			*probed_mod = NULL;
+			ret = -ENOENT;
 		}
-		/* ret will be updated by following code */
 	}
+out:
 	preempt_enable();
 	jump_label_unlock();
 
+	return ret;
+}
+
+int __kprobes register_kprobe(struct kprobe *p)
+{
+	int ret;
+	struct kprobe *old_p;
+	struct module *probed_mod;
+	kprobe_opcode_t *addr;
+
+	/* Adjust probe address from symbol */
+	addr = kprobe_addr(p);
+	if (IS_ERR(addr))
+		return PTR_ERR(addr);
+	p->addr = addr;
+
+	ret = check_kprobe_rereg(p);
+	if (ret)
+		return ret;
+
+	/* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
+	p->flags &= KPROBE_FLAG_DISABLED;
 	p->nmissed = 0;
 	INIT_LIST_HEAD(&p->list);
-	mutex_lock(&kprobe_mutex);
 
+	ret = check_kprobe_address_safe(p, &probed_mod);
+	if (ret)
+		return ret;
+
+	mutex_lock(&kprobe_mutex);
 	jump_label_lock(); /* needed to call jump_label_text_reserved() */
 
 	get_online_cpus();	/* For avoiding text_mutex deadlock. */
@@ -1410,11 +1423,6 @@ out:
 		module_put(probed_mod);
 
 	return ret;
-
-cannot_probe:
-	preempt_enable();
-	jump_label_unlock();
-	return ret;
 }
 EXPORT_SYMBOL_GPL(register_kprobe);
 
-- 
1.7.10

[RFC][PATCH 10/12] kprobes: Move locks into appropriate functions

[Steven Rostedt]

[-- Attachment #1: 0010-kprobes-Move-locks-into-appropriate-functions.patch --]
[-- Type: text/plain, Size: 4761 bytes --]

From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

Break a big critical region into fine-grained pieces at
registering kprobe path. This helps us to solve circular
locking dependency when introducing ftrace-based kprobes.

Link: http://lkml.kernel.org/r/20120605102826.27845.81689.stgit@localhost.localdomain

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/kprobes.c |   63 ++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 42 insertions(+), 21 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 6137fe3..9e47f44 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -759,20 +759,28 @@ static __kprobes void try_to_optimize_kprobe(struct kprobe *p)
 	struct kprobe *ap;
 	struct optimized_kprobe *op;
 
+	/* For preparing optimization, jump_label_text_reserved() is called */
+	jump_label_lock();
+	mutex_lock(&text_mutex);
+
 	ap = alloc_aggr_kprobe(p);
 	if (!ap)
-		return;
+		goto out;
 
 	op = container_of(ap, struct optimized_kprobe, kp);
 	if (!arch_prepared_optinsn(&op->optinsn)) {
 		/* If failed to setup optimizing, fallback to kprobe */
 		arch_remove_optimized_kprobe(op);
 		kfree(op);
-		return;
+		goto out;
 	}
 
 	init_aggr_kprobe(ap, p);
-	optimize_kprobe(ap);
+	optimize_kprobe(ap);	/* This just kicks optimizer thread */
+
+out:
+	mutex_unlock(&text_mutex);
+	jump_label_unlock();
 }
 
 #ifdef CONFIG_SYSCTL
@@ -1144,12 +1152,6 @@ static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
 	if (p->post_handler && !ap->post_handler)
 		ap->post_handler = aggr_post_handler;
 
-	if (kprobe_disabled(ap) && !kprobe_disabled(p)) {
-		ap->flags &= ~KPROBE_FLAG_DISABLED;
-		if (!kprobes_all_disarmed)
-			/* Arm the breakpoint again. */
-			__arm_kprobe(ap);
-	}
 	return 0;
 }
 
@@ -1189,11 +1191,22 @@ static int __kprobes register_aggr_kprobe(struct kprobe *orig_p,
 	int ret = 0;
 	struct kprobe *ap = orig_p;
 
+	/* For preparing optimization, jump_label_text_reserved() is called */
+	jump_label_lock();
+	/*
+	 * Get online CPUs to avoid text_mutex deadlock.with stop machine,
+	 * which is invoked by unoptimize_kprobe() in add_new_kprobe()
+	 */
+	get_online_cpus();
+	mutex_lock(&text_mutex);
+
 	if (!kprobe_aggrprobe(orig_p)) {
 		/* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
 		ap = alloc_aggr_kprobe(orig_p);
-		if (!ap)
-			return -ENOMEM;
+		if (!ap) {
+			ret = -ENOMEM;
+			goto out;
+		}
 		init_aggr_kprobe(ap, orig_p);
 	} else if (kprobe_unused(ap))
 		/* This probe is going to die. Rescue it */
@@ -1213,7 +1226,7 @@ static int __kprobes register_aggr_kprobe(struct kprobe *orig_p,
 			 * free aggr_probe. It will be used next time, or
 			 * freed by unregister_kprobe.
 			 */
-			return ret;
+			goto out;
 
 		/* Prepare optimized instructions if possible. */
 		prepare_optimized_kprobe(ap);
@@ -1228,7 +1241,20 @@ static int __kprobes register_aggr_kprobe(struct kprobe *orig_p,
 
 	/* Copy ap's insn slot to p */
 	copy_kprobe(ap, p);
-	return add_new_kprobe(ap, p);
+	ret = add_new_kprobe(ap, p);
+
+out:
+	mutex_unlock(&text_mutex);
+	put_online_cpus();
+	jump_label_unlock();
+
+	if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {
+		ap->flags &= ~KPROBE_FLAG_DISABLED;
+		if (!kprobes_all_disarmed)
+			/* Arm the breakpoint again. */
+			arm_kprobe(ap);
+	}
+	return ret;
 }
 
 static int __kprobes in_kprobes_functions(unsigned long addr)
@@ -1387,10 +1413,6 @@ int __kprobes register_kprobe(struct kprobe *p)
 		return ret;
 
 	mutex_lock(&kprobe_mutex);
-	jump_label_lock(); /* needed to call jump_label_text_reserved() */
-
-	get_online_cpus();	/* For avoiding text_mutex deadlock. */
-	mutex_lock(&text_mutex);
 
 	old_p = get_kprobe(p->addr);
 	if (old_p) {
@@ -1399,7 +1421,9 @@ int __kprobes register_kprobe(struct kprobe *p)
 		goto out;
 	}
 
+	mutex_lock(&text_mutex);	/* Avoiding text modification */
 	ret = arch_prepare_kprobe(p);
+	mutex_unlock(&text_mutex);
 	if (ret)
 		goto out;
 
@@ -1408,15 +1432,12 @@ int __kprobes register_kprobe(struct kprobe *p)
 		       &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
 
 	if (!kprobes_all_disarmed && !kprobe_disabled(p))
-		__arm_kprobe(p);
+		arm_kprobe(p);
 
 	/* Try to optimize kprobe */
 	try_to_optimize_kprobe(p);
 
 out:
-	mutex_unlock(&text_mutex);
-	put_online_cpus();
-	jump_label_unlock();
 	mutex_unlock(&kprobe_mutex);
 
 	if (probed_mod)
-- 
1.7.10

[RFC][PATCH 11/12] kprobes: introduce ftrace based optimization

[Steven Rostedt]

[-- Attachment #1: 0011-kprobes-introduce-ftrace-based-optimization.patch --]
[-- Type: text/plain, Size: 9947 bytes --]

From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

Introduce function trace based kprobes optimization.

With using ftrace optimization, kprobes on the mcount calling
address, use ftrace's mcount call instead of breakpoint.
Furthermore, this optimization works with preemptive kernel
not like as current jump-based optimization. Of cource,
this feature works only if the probe is on mcount call.

Only if kprobe.break_handler is set, that probe is not
optimized with ftrace (nor put on ftrace). The reason why this
limitation comes is that this break_handler may be used only
from jprobes which changes ip address (for fetching the function
arguments), but function tracer ignores modified ip address.

Changes in v2:
 - Fix ftrace_ops registering right after setting its filter.
 - Unregister ftrace_ops if there is no kprobe using.
 - Remove notrace dependency from __kprobes macro.

Link: http://lkml.kernel.org/r/20120605102832.27845.63461.stgit@localhost.localdomain

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/kprobes.h |   27 ++++++++++++
 kernel/kprobes.c        |  105 +++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 119 insertions(+), 13 deletions(-)

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index b6e1f8c..aa0d05e 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -38,6 +38,7 @@
 #include <linux/spinlock.h>
 #include <linux/rcupdate.h>
 #include <linux/mutex.h>
+#include <linux/ftrace.h>
 
 #ifdef CONFIG_KPROBES
 #include <asm/kprobes.h>
@@ -48,14 +49,26 @@
 #define KPROBE_REENTER		0x00000004
 #define KPROBE_HIT_SSDONE	0x00000008
 
+/*
+ * If function tracer is enabled and the arch supports full
+ * passing of pt_regs to function tracing, then kprobes can
+ * optimize on top of function tracing.
+ */
+#if defined(CONFIG_FUNCTION_TRACER) && defined(ARCH_SUPPORTS_FTRACE_SAVE_REGS) \
+	&& defined(ARCH_SUPPORTS_KPROBES_ON_FTRACE)
+# define KPROBES_CAN_USE_FTRACE
+#endif
+
 /* Attach to insert probes on any functions which should be ignored*/
 #define __kprobes	__attribute__((__section__(".kprobes.text")))
+
 #else /* CONFIG_KPROBES */
 typedef int kprobe_opcode_t;
 struct arch_specific_insn {
 	int dummy;
 };
 #define __kprobes
+
 #endif /* CONFIG_KPROBES */
 
 struct kprobe;
@@ -128,6 +141,7 @@ struct kprobe {
 				   * NOTE:
 				   * this flag is only for optimized_kprobe.
 				   */
+#define KPROBE_FLAG_FTRACE	8 /* probe is using ftrace */
 
 /* Has this kprobe gone ? */
 static inline int kprobe_gone(struct kprobe *p)
@@ -146,6 +160,13 @@ static inline int kprobe_optimized(struct kprobe *p)
 {
 	return p->flags & KPROBE_FLAG_OPTIMIZED;
 }
+
+/* Is this kprobe uses ftrace ? */
+static inline int kprobe_ftrace(struct kprobe *p)
+{
+	return p->flags & KPROBE_FLAG_FTRACE;
+}
+
 /*
  * Special probe type that uses setjmp-longjmp type tricks to resume
  * execution at a specified entry with a matching prototype corresponding
@@ -295,6 +316,12 @@ extern int proc_kprobes_optimization_handler(struct ctl_table *table,
 #endif
 
 #endif /* CONFIG_OPTPROBES */
+#ifdef KPROBES_CAN_USE_FTRACE
+extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
+				  struct pt_regs *regs);
+extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
+#endif
+
 
 /* Get the kprobe at this addr (if any) - called with preemption disabled */
 struct kprobe *get_kprobe(void *addr);
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 9e47f44..69c16ef 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -759,6 +759,10 @@ static __kprobes void try_to_optimize_kprobe(struct kprobe *p)
 	struct kprobe *ap;
 	struct optimized_kprobe *op;
 
+	/* Impossible to optimize ftrace-based kprobe */
+	if (kprobe_ftrace(p))
+		return;
+
 	/* For preparing optimization, jump_label_text_reserved() is called */
 	jump_label_lock();
 	mutex_lock(&text_mutex);
@@ -915,9 +919,64 @@ static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 }
 #endif /* CONFIG_OPTPROBES */
 
+#ifdef KPROBES_CAN_USE_FTRACE
+static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
+	.regs_func = kprobe_ftrace_handler,
+	.flags = FTRACE_OPS_FL_SAVE_REGS,
+};
+static int kprobe_ftrace_enabled;
+
+/* Must ensure p->addr is really on ftrace */
+static int __kprobes prepare_kprobe(struct kprobe *p)
+{
+	if (!kprobe_ftrace(p))
+		return arch_prepare_kprobe(p);
+
+	return arch_prepare_kprobe_ftrace(p);
+}
+
+/* Caller must lock kprobe_mutex */
+static void __kprobes arm_kprobe_ftrace(struct kprobe *p)
+{
+	int ret;
+
+	ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
+				   (unsigned long)p->addr, 0, 0);
+	WARN(ret < 0, "Failed to arm kprobe-ftrace at %p (%d)\n", p->addr, ret);
+	kprobe_ftrace_enabled++;
+	if (kprobe_ftrace_enabled == 1) {
+		ret = register_ftrace_function(&kprobe_ftrace_ops);
+		WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
+	}
+}
+
+/* Caller must lock kprobe_mutex */
+static void __kprobes disarm_kprobe_ftrace(struct kprobe *p)
+{
+	int ret;
+
+	kprobe_ftrace_enabled--;
+	if (kprobe_ftrace_enabled == 0) {
+		ret = unregister_ftrace_function(&kprobe_ftrace_ops);
+		WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
+	}
+	ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
+			   (unsigned long)p->addr, 1, 0);
+	WARN(ret < 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p->addr, ret);
+}
+#else	/* !KPROBES_CAN_USE_FTRACE */
+#define prepare_kprobe(p)	arch_prepare_kprobe(p)
+#define arm_kprobe_ftrace(p)	do {} while (0)
+#define disarm_kprobe_ftrace(p)	do {} while (0)
+#endif
+
 /* Arm a kprobe with text_mutex */
 static void __kprobes arm_kprobe(struct kprobe *kp)
 {
+	if (unlikely(kprobe_ftrace(kp))) {
+		arm_kprobe_ftrace(kp);
+		return;
+	}
 	/*
 	 * Here, since __arm_kprobe() doesn't use stop_machine(),
 	 * this doesn't cause deadlock on text_mutex. So, we don't
@@ -929,11 +988,15 @@ static void __kprobes arm_kprobe(struct kprobe *kp)
 }
 
 /* Disarm a kprobe with text_mutex */
-static void __kprobes disarm_kprobe(struct kprobe *kp)
+static void __kprobes disarm_kprobe(struct kprobe *kp, bool reopt)
 {
+	if (unlikely(kprobe_ftrace(kp))) {
+		disarm_kprobe_ftrace(kp);
+		return;
+	}
 	/* Ditto */
 	mutex_lock(&text_mutex);
-	__disarm_kprobe(kp, true);
+	__disarm_kprobe(kp, reopt);
 	mutex_unlock(&text_mutex);
 }
 
@@ -1343,6 +1406,26 @@ static __kprobes int check_kprobe_address_safe(struct kprobe *p,
 					       struct module **probed_mod)
 {
 	int ret = 0;
+	unsigned long ftrace_addr;
+
+	/*
+	 * If the address is located on a ftrace nop, set the
+	 * breakpoint to the following instruction.
+	 */
+	ftrace_addr = ftrace_location((unsigned long)p->addr);
+	if (ftrace_addr) {
+#ifdef KPROBES_CAN_USE_FTRACE
+		/* Given address is not on the instruction boundary */
+		if ((unsigned long)p->addr != ftrace_addr)
+			return -EILSEQ;
+		/* break_handler (jprobe) can not work with ftrace */
+		if (p->break_handler)
+			return -EINVAL;
+		p->flags |= KPROBE_FLAG_FTRACE;
+#else	/* !KPROBES_CAN_USE_FTRACE */
+		return -EINVAL;
+#endif
+	}
 
 	jump_label_lock();
 	preempt_disable();
@@ -1350,7 +1433,6 @@ static __kprobes int check_kprobe_address_safe(struct kprobe *p,
 	/* Ensure it is not in reserved area nor out of text */
 	if (!kernel_text_address((unsigned long) p->addr) ||
 	    in_kprobes_functions((unsigned long) p->addr) ||
-	    ftrace_text_reserved(p->addr, p->addr) ||
 	    jump_label_text_reserved(p->addr, p->addr)) {
 		ret = -EINVAL;
 		goto out;
@@ -1422,7 +1504,7 @@ int __kprobes register_kprobe(struct kprobe *p)
 	}
 
 	mutex_lock(&text_mutex);	/* Avoiding text modification */
-	ret = arch_prepare_kprobe(p);
+	ret = prepare_kprobe(p);
 	mutex_unlock(&text_mutex);
 	if (ret)
 		goto out;
@@ -1480,7 +1562,7 @@ static struct kprobe *__kprobes __disable_kprobe(struct kprobe *p)
 
 		/* Try to disarm and disable this/parent probe */
 		if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
-			disarm_kprobe(orig_p);
+			disarm_kprobe(orig_p, true);
 			orig_p->flags |= KPROBE_FLAG_DISABLED;
 		}
 	}
@@ -2078,10 +2160,11 @@ static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
 
 	if (!pp)
 		pp = p;
-	seq_printf(pi, "%s%s%s\n",
+	seq_printf(pi, "%s%s%s%s\n",
 		(kprobe_gone(p) ? "[GONE]" : ""),
 		((kprobe_disabled(p) && !kprobe_gone(p)) ?  "[DISABLED]" : ""),
-		(kprobe_optimized(pp) ? "[OPTIMIZED]" : ""));
+		(kprobe_optimized(pp) ? "[OPTIMIZED]" : ""),
+		(kprobe_ftrace(pp) ? "[FTRACE]" : ""));
 }
 
 static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
@@ -2160,14 +2243,12 @@ static void __kprobes arm_all_kprobes(void)
 		goto already_enabled;
 
 	/* Arming kprobes doesn't optimize kprobe itself */
-	mutex_lock(&text_mutex);
 	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 		head = &kprobe_table[i];
 		hlist_for_each_entry_rcu(p, node, head, hlist)
 			if (!kprobe_disabled(p))
-				__arm_kprobe(p);
+				arm_kprobe(p);
 	}
-	mutex_unlock(&text_mutex);
 
 	kprobes_all_disarmed = false;
 	printk(KERN_INFO "Kprobes globally enabled\n");
@@ -2195,15 +2276,13 @@ static void __kprobes disarm_all_kprobes(void)
 	kprobes_all_disarmed = true;
 	printk(KERN_INFO "Kprobes globally disabled\n");
 
-	mutex_lock(&text_mutex);
 	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 		head = &kprobe_table[i];
 		hlist_for_each_entry_rcu(p, node, head, hlist) {
 			if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
-				__disarm_kprobe(p, false);
+				disarm_kprobe(p, false);
 		}
 	}
-	mutex_unlock(&text_mutex);
 	mutex_unlock(&kprobe_mutex);
 
 	/* Wait for disarming all kprobes by optimizer */
-- 
1.7.10

[RFC][PATCH 12/12] kprobes/x86: ftrace based optimization for x86

[Steven Rostedt]

[-- Attachment #1: 0012-kprobes-x86-ftrace-based-optimization-for-x86.patch --]
[-- Type: text/plain, Size: 3956 bytes --]

From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

Add function tracer based kprobe optimization support
handlers on x86. This allows kprobes to use function
tracer for probing on mcount call.

Link: http://lkml.kernel.org/r/20120605102838.27845.26317.stgit@localhost.localdomain

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

[ Updated to new port of ftrace save regs functions ]

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 arch/x86/include/asm/kprobes.h |    1 +
 arch/x86/kernel/kprobes.c      |   48 ++++++++++++++++++++++++++++++++++++++++
 include/linux/kprobes.h        |    2 +-
 kernel/kprobes.c               |    2 +-
 4 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kprobes.h b/arch/x86/include/asm/kprobes.h
index 5478825..d3ddd17 100644
--- a/arch/x86/include/asm/kprobes.h
+++ b/arch/x86/include/asm/kprobes.h
@@ -27,6 +27,7 @@
 #include <asm/insn.h>
 
 #define  __ARCH_WANT_KPROBES_INSN_SLOT
+#define  ARCH_SUPPORTS_KPROBES_ON_FTRACE
 
 struct pt_regs;
 struct kprobe;
diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index e2f751e..47ae102 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -1052,6 +1052,54 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 	return 0;
 }
 
+#ifdef KPROBES_CAN_USE_FTRACE
+/* Ftrace callback handler for kprobes */
+void __kprobes kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
+				     struct ftrace_ops *ops, struct pt_regs *regs)
+{
+	struct kprobe *p;
+	struct kprobe_ctlblk *kcb;
+	unsigned long flags;
+
+	/* Disable irq for emulating a breakpoint and avoiding preempt */
+	local_irq_save(flags);
+
+	p = get_kprobe((kprobe_opcode_t *)ip);
+	if (unlikely(!p) || kprobe_disabled(p))
+		goto end;
+
+	kcb = get_kprobe_ctlblk();
+	if (kprobe_running()) {
+		kprobes_inc_nmissed_count(p);
+	} else {
+		regs->ip += sizeof(kprobe_opcode_t);
+
+		__this_cpu_write(current_kprobe, p);
+		kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+		if (p->pre_handler)
+			p->pre_handler(p, regs);
+
+		if (unlikely(p->post_handler)) {
+			/* Emulate singlestep as if there is a 5byte nop */
+			regs->ip = ip + MCOUNT_INSN_SIZE;
+			kcb->kprobe_status = KPROBE_HIT_SSDONE;
+			p->post_handler(p, regs, 0);
+		}
+		__this_cpu_write(current_kprobe, NULL);
+		regs->ip = ip;	/* Recover for next callback */
+	}
+end:
+	local_irq_restore(flags);
+}
+
+int __kprobes arch_prepare_kprobe_ftrace(struct kprobe *p)
+{
+	p->ainsn.insn = NULL;
+	p->ainsn.boostable = -1;
+	return 0;
+}
+#endif
+
 int __init arch_init_kprobes(void)
 {
 	return arch_init_optprobes();
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index aa0d05e..23755ba 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -318,7 +318,7 @@ extern int proc_kprobes_optimization_handler(struct ctl_table *table,
 #endif /* CONFIG_OPTPROBES */
 #ifdef KPROBES_CAN_USE_FTRACE
 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
-				  struct pt_regs *regs);
+				  struct ftrace_ops *ops, struct pt_regs *regs);
 extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
 #endif
 
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 69c16ef..35b4315 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -921,7 +921,7 @@ static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 
 #ifdef KPROBES_CAN_USE_FTRACE
 static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
-	.regs_func = kprobe_ftrace_handler,
+	.func = kprobe_ftrace_handler,
 	.flags = FTRACE_OPS_FL_SAVE_REGS,
 };
 static int kprobe_ftrace_enabled;
-- 
1.7.10

Re: [RFC][PATCH 06/12] ftrace/x86: Add save_regs for i386 function calls

[Steven Rostedt]

On Tue, 2012-06-05 at 23:51 -0400, Steven Rostedt wrote:

> +ENTRY(ftrace_regs_caller)
> +	pushf	/* push flags before compare */
> +	cmpl $0, function_trace_stop
> +	jne ftrace_exit
> +
> +

Masami,

Do we really need to push before the compare? As the compare flags are
really meaningless with calling functions, and here we are only trying
to hide what the cmpl did. If something else was tracing without regs,
and we put a probe just after the nop, then it would include the cmpl
changes. My version of the patch doesn't restore the flags, so two
probes would have different values. But again, do we care? What would
need to know the value of cmp flags when calling into a function when
they are not going to be restored anyway.

-- Steve

Re: [RFC][PATCH 06/12] ftrace/x86: Add save_regs for i386 function calls

[Masami Hiramatsu]

(2012/06/06 23:37), Steven Rostedt wrote:
> On Tue, 2012-06-05 at 23:51 -0400, Steven Rostedt wrote:
> 
>> +ENTRY(ftrace_regs_caller)
>> +	pushf	/* push flags before compare */
>> +	cmpl $0, function_trace_stop
>> +	jne ftrace_exit
>> +
>> +
> 
> Masami,
> 
> Do we really need to push before the compare? As the compare flags are
> really meaningless with calling functions, and here we are only trying
> to hide what the cmpl did. If something else was tracing without regs,
> and we put a probe just after the nop, then it would include the cmpl
> changes. My version of the patch doesn't restore the flags, so two
> probes would have different values. But again, do we care? What would
> need to know the value of cmp flags when calling into a function when
> they are not going to be restored anyway.

Yes, it needs to be saved and restored too, for transparency.
If we don't guarantee it, users must check whether a probe
can do what they are doing, before they put the probe. And
if not, they must find another appropriate place. It's not
compatible with previous kprobes.

Actually, I think we can push flags after compare if we
add a note on kprobes document, so that user can expect
compare flags will be not correct if KPROBE_FLAG_FTRACE
is set. (Of course, it is better to provide an API
(ftrace_location is enough?) for giving him a hint how he
can get a correct flags with kprobes)

But if you'd like to introduce -mfentry, I hope ftrace to
restore flags, which will be useful for debugging/investigation
by tweaking flags while executing a function.

Thank you,

-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com