[v2,RESEND] function_graph: Support recording and printing the function return address

Commit Message

Donglin Peng Oct. 9, 2024, 3:03 a.m. UTC

From: Donglin Peng <[e-mail]>

When using function_graph tracer to analyze the flow of kernel function
execution, it is often necessary to quickly locate the exact line of code
where the call occurs. While this may be easy at times, it can be more
time-consuming when some functions are inlined or the flow is too long.

This feature aims to simplify the process by recording the return address
of traced funcions and printing it when outputing trace logs.

To enhance human readability, the prefix 'ret=' is used for the kernel return
value, while '<-' serves as the prefix for the return address in trace logs to
make it look more like the function tracer.

A new trace option named 'funcgraph-retaddr' has been introduced, and the
existing option 'sym-addr' can be used to control the format of the return
address.

See below logs with both funcgraph-retval and funcgraph-retaddr enabled.

0)             | load_elf_binary() { /* <-bprm_execve+0x249/0x600 */
0)             |   load_elf_phdrs() { /* <-load_elf_binary+0x84/0x1730 */
0)             |     __kmalloc_noprof() { /* <-load_elf_phdrs+0x4a/0xb0 */
0)   3.657 us  |       __cond_resched(); /* <-__kmalloc_noprof+0x28c/0x390 ret=0x0 */
0) + 24.335 us |     } /* __kmalloc_noprof ret=0xffff8882007f3000 */
0)             |     kernel_read() { /* <-load_elf_phdrs+0x6c/0xb0 */
0)             |       rw_verify_area() { /* <-kernel_read+0x2b/0x50 */
0)             |         security_file_permission() { /* <-kernel_read+0x2b/0x50 */
0)             |           selinux_file_permission() { /* <-security_file_permission+0x26/0x40 */
0)             |             __inode_security_revalidate() { /* <-selinux_file_permission+0x6d/0x140 */
0)   2.034 us  |               __cond_resched(); /* <-__inode_security_revalidate+0x5f/0x80 ret=0x0 */
0)   6.602 us  |             } /* __inode_security_revalidate ret=0x0 */
0)   2.214 us  |             avc_policy_seqno(); /* <-selinux_file_permission+0x107/0x140 ret=0x0 */
0) + 16.670 us |           } /* selinux_file_permission ret=0x0 */
0) + 20.809 us |         } /* security_file_permission ret=0x0 */
0) + 25.217 us |       } /* rw_verify_area ret=0x0 */
0)             |       __kernel_read() { /* <-load_elf_phdrs+0x6c/0xb0 */
0)             |         ext4_file_read_iter() { /* <-__kernel_read+0x160/0x2e0 */

Then, we can use the faddr2line to locate the source code, for example:

$ ./scripts/faddr2line ./vmlinux load_elf_phdrs+0x6c/0xb0
load_elf_phdrs+0x6c/0xb0:
elf_read at fs/binfmt_elf.c:471
(inlined by) load_elf_phdrs at fs/binfmt_elf.c:531

Reported-by: kernel test robot <[e-mail]>
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/
Signed-off-by: Donglin Peng <[e-mail]>
---
v1 -> v2:
 - Fix build errors reported by kernel test robot
 - Use CONFIG_FUNCTION_GRAPH_RETADDR to enclose more code

rfc -> v1:
 - Invoke 'ftrace_graph_ret_addr' to obtain the actual return address
 - Refine the prefix preceding the return addess and the return value
 - Print the return address firstly when both funcgraph-retval and
   funcgraph-retaddr are enabled
 - Create a new event named 'fgraph_retaddr_entry' in order not to save the
   return address to the ring buffer when 'funcgraph-retaddr' is disabled,
   thereby reducing memory overhead
 - Add a kernel config named CONFIG_FUNCTION_GRAPH_RETADDR
 - Update fgraph-retval.tc to fix selftest issues
---
 include/linux/ftrace.h                        |  27 ++-
 kernel/trace/Kconfig                          |  10 +
 kernel/trace/fgraph.c                         |  22 +-
 kernel/trace/ftrace.c                         |   3 +-
 kernel/trace/trace.h                          |  11 +-
 kernel/trace/trace_entries.h                  |  29 ++-
 kernel/trace/trace_functions_graph.c          | 212 ++++++++++++++----
 kernel/trace/trace_irqsoff.c                  |   3 +-
 kernel/trace/trace_sched_wakeup.c             |   3 +-
 kernel/trace/trace_selftest.c                 |   9 +-
 .../ftrace/test.d/ftrace/fgraph-retval.tc     |   2 +-
 11 files changed, 271 insertions(+), 60 deletions(-)

Comments

Steven Rostedt Oct. 9, 2024, 1:37 p.m. UTC | #1

On Wed,  9 Oct 2024 11:03:40 +0800
Donglin Peng <[e-mail]> wrote:

> From: Donglin Peng <[e-mail]>
> 
> When using function_graph tracer to analyze the flow of kernel function
> execution, it is often necessary to quickly locate the exact line of code
> where the call occurs. While this may be easy at times, it can be more
> time-consuming when some functions are inlined or the flow is too long.
> 
> This feature aims to simplify the process by recording the return address
> of traced funcions and printing it when outputing trace logs.
> 
> To enhance human readability, the prefix 'ret=' is used for the kernel return
> value, while '<-' serves as the prefix for the return address in trace logs to
> make it look more like the function tracer.
> 
> A new trace option named 'funcgraph-retaddr' has been introduced, and the
> existing option 'sym-addr' can be used to control the format of the return
> address.
> 

Is there a reason for the resend? I already have it in my for-next branch.

-- Steve

Donglin Peng Oct. 9, 2024, 2:01 p.m. UTC | #2

On Wed, Oct 9, 2024 at 9:37 PM Steven Rostedt <[e-mail]> wrote:
>
> On Wed,  9 Oct 2024 11:03:40 +0800
> Donglin Peng <[e-mail]> wrote:
>
> > From: Donglin Peng <[e-mail]>
> >
> > When using function_graph tracer to analyze the flow of kernel function
> > execution, it is often necessary to quickly locate the exact line of code
> > where the call occurs. While this may be easy at times, it can be more
> > time-consuming when some functions are inlined or the flow is too long.
> >
> > This feature aims to simplify the process by recording the return address
> > of traced funcions and printing it when outputing trace logs.
> >
> > To enhance human readability, the prefix 'ret=' is used for the kernel return
> > value, while '<-' serves as the prefix for the return address in trace logs to
> > make it look more like the function tracer.
> >
> > A new trace option named 'funcgraph-retaddr' has been introduced, and the
> > existing option 'sym-addr' can be used to control the format of the return
> > address.
> >
>
> Is there a reason for the resend? I already have it in my for-next branch.

I'm sorry and I did not notice it.

>
> -- Steve

Steven Rostedt Oct. 9, 2024, 2:45 p.m. UTC | #3

On Wed, 9 Oct 2024 22:01:51 +0800
Donglin Peng <[e-mail]> wrote:

> > Is there a reason for the resend? I already have it in my for-next branch.  
> 
> I'm sorry and I did not notice it.

You were Cc'd:

  https://lore.kernel.org/all/[e-mail]/

That's why I send these out.

-- Steve

Donglin Peng Oct. 9, 2024, 3:03 p.m. UTC | #4

On Wed, Oct 9, 2024 at 10:45 PM Steven Rostedt <[e-mail]> wrote:
>
> On Wed, 9 Oct 2024 22:01:51 +0800
> Donglin Peng <[e-mail]> wrote:
>
> > > Is there a reason for the resend? I already have it in my for-next branch.
> >
> > I'm sorry and I did not notice it.
>
> You were Cc'd:
>
>   https://lore.kernel.org/all/[e-mail]/
>
> That's why I send these out.

Thanks, this issue is due to a misconfiguration in my email settings.

>
> -- Steve

Masami Hiramatsu (Google) Oct. 9, 2024, 4:32 p.m. UTC | #5

On Wed,  9 Oct 2024 11:03:40 +0800
Donglin Peng <[e-mail]> wrote:

> From: Donglin Peng <[e-mail]>
> 
> When using function_graph tracer to analyze the flow of kernel function
> execution, it is often necessary to quickly locate the exact line of code
> where the call occurs. While this may be easy at times, it can be more
> time-consuming when some functions are inlined or the flow is too long.
> 
> This feature aims to simplify the process by recording the return address
> of traced funcions and printing it when outputing trace logs.
> 
> To enhance human readability, the prefix 'ret=' is used for the kernel return
> value, while '<-' serves as the prefix for the return address in trace logs to
> make it look more like the function tracer.
> 
> A new trace option named 'funcgraph-retaddr' has been introduced, and the
> existing option 'sym-addr' can be used to control the format of the return
> address.
> 
> See below logs with both funcgraph-retval and funcgraph-retaddr enabled.
> 
> 0)             | load_elf_binary() { /* <-bprm_execve+0x249/0x600 */
> 0)             |   load_elf_phdrs() { /* <-load_elf_binary+0x84/0x1730 */
> 0)             |     __kmalloc_noprof() { /* <-load_elf_phdrs+0x4a/0xb0 */
> 0)   3.657 us  |       __cond_resched(); /* <-__kmalloc_noprof+0x28c/0x390 ret=0x0 */
> 0) + 24.335 us |     } /* __kmalloc_noprof ret=0xffff8882007f3000 */
> 0)             |     kernel_read() { /* <-load_elf_phdrs+0x6c/0xb0 */
> 0)             |       rw_verify_area() { /* <-kernel_read+0x2b/0x50 */
> 0)             |         security_file_permission() { /* <-kernel_read+0x2b/0x50 */
> 0)             |           selinux_file_permission() { /* <-security_file_permission+0x26/0x40 */
> 0)             |             __inode_security_revalidate() { /* <-selinux_file_permission+0x6d/0x140 */
> 0)   2.034 us  |               __cond_resched(); /* <-__inode_security_revalidate+0x5f/0x80 ret=0x0 */
> 0)   6.602 us  |             } /* __inode_security_revalidate ret=0x0 */
> 0)   2.214 us  |             avc_policy_seqno(); /* <-selinux_file_permission+0x107/0x140 ret=0x0 */
> 0) + 16.670 us |           } /* selinux_file_permission ret=0x0 */
> 0) + 20.809 us |         } /* security_file_permission ret=0x0 */
> 0) + 25.217 us |       } /* rw_verify_area ret=0x0 */
> 0)             |       __kernel_read() { /* <-load_elf_phdrs+0x6c/0xb0 */
> 0)             |         ext4_file_read_iter() { /* <-__kernel_read+0x160/0x2e0 */
> 
> Then, we can use the faddr2line to locate the source code, for example:
> 
> $ ./scripts/faddr2line ./vmlinux load_elf_phdrs+0x6c/0xb0
> load_elf_phdrs+0x6c/0xb0:
> elf_read at fs/binfmt_elf.c:471
> (inlined by) load_elf_phdrs at fs/binfmt_elf.c:531

Hi, I found this introduced "extras" to the fgraph callback interface
but it is only used in function_graph tracer. Can we move this in the
function_graph tracer, like below?

Thank you,


From 8c2851452dd11a3a20ab22bd6bf8dd663c3c4b9c Mon Sep 17 00:00:00 2001
From: "Masami Hiramatsu (Google)" <[e-mail]>
Date: Thu, 10 Oct 2024 00:58:12 +0900
Subject: [PATCH] tracing/fgraph: Simplify return address printing in function
 graph tracer

Simplify return address printing in the function graph tracer by removing
fgraph_extras. Since this feature is only used by the function graph
tracer and we can check the flag directly in the function graph tracer,
we can remove the fgraph_extras from the fgraph callback.

Signed-off-by: Masami Hiramatsu (Google) <[e-mail]>
---
 include/linux/ftrace.h               | 16 ++++------
 kernel/trace/fgraph.c                | 45 ++++++++++++++++++----------
 kernel/trace/ftrace.c                |  3 +-
 kernel/trace/trace.h                 |  3 +-
 kernel/trace/trace_functions_graph.c | 14 ++++-----
 kernel/trace/trace_irqsoff.c         |  3 +-
 kernel/trace/trace_sched_wakeup.c    |  3 +-
 kernel/trace/trace_selftest.c        |  8 ++---
 8 files changed, 48 insertions(+), 47 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 2ac3b3b53cd0..997e1f0335b6 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1068,29 +1068,20 @@ struct ftrace_graph_ret {
 	unsigned long long rettime;
 } __packed;
 
-struct fgraph_extras;
 struct fgraph_ops;
 
 /* Type of the callback handlers for tracing function graph*/
 typedef void (*trace_func_graph_ret_t)(struct ftrace_graph_ret *,
 				       struct fgraph_ops *); /* return */
 typedef int (*trace_func_graph_ent_t)(struct ftrace_graph_ent *,
-				      struct fgraph_ops *,
-				      struct fgraph_extras *); /* entry */
+				      struct fgraph_ops *); /* entry */
 
 extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace,
-				   struct fgraph_ops *gops,
-				   struct fgraph_extras *extras);
+				   struct fgraph_ops *gops);
 bool ftrace_pids_enabled(struct ftrace_ops *ops);
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 
-/* Used to convey some extra datas when creating a graph entry */
-struct fgraph_extras {
-	u32 flags;
-	unsigned long retaddr;
-};
-
 struct fgraph_ops {
 	trace_func_graph_ent_t		entryfunc;
 	trace_func_graph_ret_t		retfunc;
@@ -1131,12 +1122,15 @@ function_graph_enter(unsigned long ret, unsigned long func,
 
 struct ftrace_ret_stack *
 ftrace_graph_get_ret_stack(struct task_struct *task, int skip);
+unsigned long ftrace_graph_top_ret_addr(struct task_struct *task);
 
 unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
 				    unsigned long ret, unsigned long *retp);
 unsigned long *fgraph_get_task_var(struct fgraph_ops *gops);
 
 u32 graph_tracer_flags_get(u32 flags);
+#define graph_tracer_flags_is_set(flags)	\
+	(graph_tracer_flags_get(flags) == (flags))
 
 /*
  * Sometimes we don't want to trace a function with the function
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 27e523f01ed2..ee829d65f301 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -290,8 +290,7 @@ static inline unsigned long make_data_type_val(int idx, int size, int offset)
 }
 
 /* ftrace_graph_entry set to this to tell some archs to run function graph */
-static int entry_run(struct ftrace_graph_ent *trace, struct fgraph_ops *ops,
-		     struct fgraph_extras *extras)
+static int entry_run(struct ftrace_graph_ent *trace, struct fgraph_ops *ops)
 {
 	return 0;
 }
@@ -519,8 +518,7 @@ int __weak ftrace_disable_ftrace_graph_caller(void)
 #endif
 
 int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace,
-			    struct fgraph_ops *gops,
-			    struct fgraph_extras *extras)
+			    struct fgraph_ops *gops)
 {
 	return 0;
 }
@@ -648,20 +646,13 @@ int function_graph_enter(unsigned long ret, unsigned long func,
 			 unsigned long frame_pointer, unsigned long *retp)
 {
 	struct ftrace_graph_ent trace;
-	struct fgraph_extras extras;
 	unsigned long bitmap = 0;
 	int offset;
 	int i;
-	int idx = 0;
 
 	trace.func = func;
 	trace.depth = ++current->curr_ret_depth;
 
-	extras.flags = graph_tracer_flags_get(TRACE_GRAPH_PRINT_RETADDR);
-	if (IS_ENABLED(CONFIG_FUNCTION_GRAPH_RETADDR)
-		&& extras.flags & TRACE_GRAPH_PRINT_RETADDR)
-		extras.retaddr = ftrace_graph_ret_addr(current, &idx, ret, retp);
-
 	offset = ftrace_push_return_trace(ret, func, frame_pointer, retp, 0);
 	if (offset < 0)
 		goto out;
@@ -670,7 +661,7 @@ int function_graph_enter(unsigned long ret, unsigned long func,
 	if (static_branch_likely(&fgraph_do_direct)) {
 		int save_curr_ret_stack = current->curr_ret_stack;
 
-		if (static_call(fgraph_func)(&trace, fgraph_direct_gops, &extras))
+		if (static_call(fgraph_func)(&trace, fgraph_direct_gops))
 			bitmap |= BIT(fgraph_direct_gops->idx);
 		else
 			/* Clear out any saved storage */
@@ -688,7 +679,7 @@ int function_graph_enter(unsigned long ret, unsigned long func,
 
 			save_curr_ret_stack = current->curr_ret_stack;
 			if (ftrace_ops_test(&gops->ops, func, NULL) &&
-			    gops->entryfunc(&trace, gops, &extras))
+			    gops->entryfunc(&trace, gops))
 				bitmap |= BIT(i);
 			else
 				/* Clear out any saved storage */
@@ -905,6 +896,29 @@ ftrace_graph_get_ret_stack(struct task_struct *task, int idx)
 	return ret_stack;
 }
 
+/**
+ * ftrace_graph_top_ret_addr - return the top return address in the shadow stack
+ * @task: The task to read the shadow stack from.
+ *
+ * Return the first return address on the shadow stack of the @task, which is
+ * not the fgraph's return_to_handler.
+ */
+unsigned long ftrace_graph_top_ret_addr(struct task_struct *task)
+{
+	unsigned long return_handler = (unsigned long)dereference_kernel_function_descriptor(return_to_handler);
+	struct ftrace_ret_stack *ret_stack = NULL;
+	int offset = task->curr_ret_stack;
+
+	if (offset < 0)
+		return 0;
+
+	do {
+		ret_stack = get_ret_stack(task, offset, &offset);
+	} while (ret_stack && ret_stack->ret == return_handler);
+
+	return ret_stack ? ret_stack->ret : 0;
+}
+
 /**
  * ftrace_graph_ret_addr - return the original value of the return address
  * @task: The task the unwinder is being executed on
@@ -1145,8 +1159,7 @@ void ftrace_graph_exit_task(struct task_struct *t)
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 static int fgraph_pid_func(struct ftrace_graph_ent *trace,
-			   struct fgraph_ops *gops,
-			   struct fgraph_extras *extras)
+			   struct fgraph_ops *gops)
 {
 	struct trace_array *tr = gops->ops.private;
 	int pid;
@@ -1160,7 +1173,7 @@ static int fgraph_pid_func(struct ftrace_graph_ent *trace,
 			return 0;
 	}
 
-	return gops->saved_func(trace, gops, NULL);
+	return gops->saved_func(trace, gops);
 }
 
 void fgraph_update_pid_func(void)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 5d87dac83b80..cae388122ca8 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -827,8 +827,7 @@ struct profile_fgraph_data {
 };
 
 static int profile_graph_entry(struct ftrace_graph_ent *trace,
-			       struct fgraph_ops *gops,
-			       struct fgraph_extras *extras)
+			       struct fgraph_ops *gops)
 {
 	struct profile_fgraph_data *profile_data;
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 13f08f257c0b..6adf48ef4312 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -695,8 +695,7 @@ void trace_default_header(struct seq_file *m);
 void print_trace_header(struct seq_file *m, struct trace_iterator *iter);
 
 void trace_graph_return(struct ftrace_graph_ret *trace, struct fgraph_ops *gops);
-int trace_graph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops,
-		      struct fgraph_extras *extras);
+int trace_graph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);
 
 void tracing_start_cmdline_record(void);
 void tracing_stop_cmdline_record(void);
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 3dd63ae2afe8..e3cda79653ee 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -179,8 +179,7 @@ struct fgraph_times {
 };
 
 int trace_graph_entry(struct ftrace_graph_ent *trace,
-		      struct fgraph_ops *gops,
-		      struct fgraph_extras *extras)
+		      struct fgraph_ops *gops)
 {
 	unsigned long *task_var = fgraph_get_task_var(gops);
 	struct trace_array *tr = gops->private;
@@ -246,11 +245,12 @@ int trace_graph_entry(struct ftrace_graph_ent *trace,
 	disabled = atomic_inc_return(&data->disabled);
 	if (likely(disabled == 1)) {
 		trace_ctx = tracing_gen_ctx_flags(flags);
-		if (unlikely(IS_ENABLED(CONFIG_FUNCTION_GRAPH_RETADDR) && extras
-				&& (extras->flags & TRACE_GRAPH_PRINT_RETADDR)))
-			ret = __trace_graph_retaddr_entry(tr, trace, trace_ctx,
-							  extras->retaddr);
-		else
+		if (unlikely(IS_ENABLED(CONFIG_FUNCTION_GRAPH_RETADDR) &&
+			graph_tracer_flags_is_set(TRACE_GRAPH_PRINT_RETADDR))) {
+			unsigned long retaddr = ftrace_graph_top_ret_addr(current);
+
+			ret = __trace_graph_retaddr_entry(tr, trace, trace_ctx, retaddr);
+		} else
 			ret = __trace_graph_entry(tr, trace, trace_ctx);
 	} else {
 		ret = 0;
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index eb3aa36cf10f..fce064e20570 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -176,8 +176,7 @@ static int irqsoff_display_graph(struct trace_array *tr, int set)
 }
 
 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace,
-			       struct fgraph_ops *gops,
-			       struct fgraph_extras *extras)
+			       struct fgraph_ops *gops)
 {
 	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 155de2551507..ae2ace5e515a 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -113,8 +113,7 @@ static int wakeup_display_graph(struct trace_array *tr, int set)
 }
 
 static int wakeup_graph_entry(struct ftrace_graph_ent *trace,
-			      struct fgraph_ops *gops,
-			      struct fgraph_extras *extras)
+			      struct fgraph_ops *gops)
 {
 	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 fbb99f8c8062..d3a14ae47e26 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -774,8 +774,7 @@ struct fgraph_fixture {
 };
 
 static __init int store_entry(struct ftrace_graph_ent *trace,
-			      struct fgraph_ops *gops,
-			      struct fgraph_extras *extras)
+			      struct fgraph_ops *gops)
 {
 	struct fgraph_fixture *fixture = container_of(gops, struct fgraph_fixture, gops);
 	const char *type = fixture->store_type_name;
@@ -1026,8 +1025,7 @@ static unsigned int graph_hang_thresh;
 
 /* Wrap the real function entry probe to avoid possible hanging */
 static int trace_graph_entry_watchdog(struct ftrace_graph_ent *trace,
-				      struct fgraph_ops *gops,
-				      struct fgraph_extras *extras)
+				      struct fgraph_ops *gops)
 {
 	/* This is harmlessly racy, we want to approximately detect a hang */
 	if (unlikely(++graph_hang_thresh > GRAPH_MAX_FUNC_TEST)) {
@@ -1041,7 +1039,7 @@ static int trace_graph_entry_watchdog(struct ftrace_graph_ent *trace,
 		return 0;
 	}
 
-	return trace_graph_entry(trace, gops, NULL);
+	return trace_graph_entry(trace, gops);
 }
 
 static struct fgraph_ops fgraph_ops __initdata  = {

Steven Rostedt Oct. 9, 2024, 5:19 p.m. UTC | #6

On Thu, 10 Oct 2024 01:32:22 +0900
Masami Hiramatsu (Google) <[e-mail]> wrote:

> >From 8c2851452dd11a3a20ab22bd6bf8dd663c3c4b9c Mon Sep 17 00:00:00 2001  
> From: "Masami Hiramatsu (Google)" <[e-mail]>
> Date: Thu, 10 Oct 2024 00:58:12 +0900
> Subject: [PATCH] tracing/fgraph: Simplify return address printing in function
>  graph tracer
> 
> Simplify return address printing in the function graph tracer by removing
> fgraph_extras. Since this feature is only used by the function graph
> tracer and we can check the flag directly in the function graph tracer,
> we can remove the fgraph_extras from the fgraph callback.
> 
> Signed-off-by: Masami Hiramatsu (Google) <[e-mail]>
> ---
>  include/linux/ftrace.h               | 16 ++++------
>  kernel/trace/fgraph.c                | 45 ++++++++++++++++++----------
>  kernel/trace/ftrace.c                |  3 +-
>  kernel/trace/trace.h                 |  3 +-
>  kernel/trace/trace_functions_graph.c | 14 ++++-----
>  kernel/trace/trace_irqsoff.c         |  3 +-
>  kernel/trace/trace_sched_wakeup.c    |  3 +-
>  kernel/trace/trace_selftest.c        |  8 ++---
>  8 files changed, 48 insertions(+), 47 deletions(-)
> 

Hi Masami,

Care to send this as a real patch?

-- Steve

Masami Hiramatsu (Google) Oct. 9, 2024, 11:26 p.m. UTC | #7

On Wed, 9 Oct 2024 13:19:20 -0400
Steven Rostedt <[e-mail]> wrote:

> 
> Hi Masami,
> 
> Care to send this as a real patch?

Yes, let me send it.

Thanks,

Patch

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index fd5e84d0ec47..8a0d878f6c9c 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1014,6 +1014,17 @@  struct ftrace_graph_ent {
 	int depth;
 } __packed;
 
+/*
+ * Structure that defines an entry function trace with retaddr.
+ * It's already packed but the attribute "packed" is needed
+ * to remove extra padding at the end.
+ */
+struct fgraph_retaddr_ent {
+	unsigned long func; /* Current function */
+	int depth;
+	unsigned long retaddr;  /* Return address */
+} __packed;
+
 /*
  * Structure that defines a return function trace.
  * It's already packed but the attribute "packed" is needed
@@ -1031,19 +1042,29 @@  struct ftrace_graph_ret {
 	unsigned long long rettime;
 } __packed;
 
+struct fgraph_extras;
 struct fgraph_ops;
 
 /* Type of the callback handlers for tracing function graph*/
 typedef void (*trace_func_graph_ret_t)(struct ftrace_graph_ret *,
 				       struct fgraph_ops *); /* return */
 typedef int (*trace_func_graph_ent_t)(struct ftrace_graph_ent *,
-				      struct fgraph_ops *); /* entry */
+				      struct fgraph_ops *,
+				      struct fgraph_extras *); /* entry */
 
-extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);
+extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace,
+				   struct fgraph_ops *gops,
+				   struct fgraph_extras *extras);
 bool ftrace_pids_enabled(struct ftrace_ops *ops);
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 
+/* Used to convey some extra datas when creating a graph entry */
+struct fgraph_extras {
+	u32 flags;
+	unsigned long retaddr;
+};
+
 struct fgraph_ops {
 	trace_func_graph_ent_t		entryfunc;
 	trace_func_graph_ret_t		retfunc;
@@ -1092,6 +1113,8 @@  unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
 				    unsigned long ret, unsigned long *retp);
 unsigned long *fgraph_get_task_var(struct fgraph_ops *gops);
 
+u32 graph_tracer_flags_get(u32 flags);
+
 /*
  * Sometimes we don't want to trace a function with the function
  * graph tracer but we want them to keep traced by the usual function
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 721c3b221048..74c2b1d43bb9 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -242,6 +242,16 @@  config FUNCTION_GRAPH_RETVAL
 	  enable it via the trace option funcgraph-retval.
 	  See Documentation/trace/ftrace.rst
 
+config FUNCTION_GRAPH_RETADDR
+	bool "Kernel Function Graph Return Address"
+	depends on FUNCTION_GRAPH_TRACER
+	default n
+	help
+	  Support recording and printing the function return address when
+	  using function graph tracer. It can be helpful to locate code line that
+	  the function is called. This feature is off by default, and you can
+	  enable it via the trace option funcgraph-retaddr.
+
 config DYNAMIC_FTRACE
 	bool "enable/disable function tracing dynamically"
 	depends on FUNCTION_TRACER
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index d7d4fb403f6f..4bcbae5a9a0b 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -290,7 +290,8 @@  static inline unsigned long make_data_type_val(int idx, int size, int offset)
 }
 
 /* ftrace_graph_entry set to this to tell some archs to run function graph */
-static int entry_run(struct ftrace_graph_ent *trace, struct fgraph_ops *ops)
+static int entry_run(struct ftrace_graph_ent *trace, struct fgraph_ops *ops,
+		     struct fgraph_extras *extras)
 {
 	return 0;
 }
@@ -484,7 +485,8 @@  int __weak ftrace_disable_ftrace_graph_caller(void)
 #endif
 
 int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace,
-			    struct fgraph_ops *gops)
+			    struct fgraph_ops *gops,
+			    struct fgraph_extras *extras)
 {
 	return 0;
 }
@@ -616,13 +618,20 @@  int function_graph_enter(unsigned long ret, unsigned long func,
 			 unsigned long frame_pointer, unsigned long *retp)
 {
 	struct ftrace_graph_ent trace;
+	struct fgraph_extras extras;
 	unsigned long bitmap = 0;
 	int offset;
 	int i;
+	int idx = 0;
 
 	trace.func = func;
 	trace.depth = ++current->curr_ret_depth;
 
+	extras.flags = graph_tracer_flags_get(TRACE_GRAPH_PRINT_RETADDR);
+	if (IS_ENABLED(CONFIG_FUNCTION_GRAPH_RETADDR)
+		&& extras.flags & TRACE_GRAPH_PRINT_RETADDR)
+		extras.retaddr = ftrace_graph_ret_addr(current, &idx, ret, retp);
+
 	offset = ftrace_push_return_trace(ret, func, frame_pointer, retp, 0);
 	if (offset < 0)
 		goto out;
@@ -631,7 +640,7 @@  int function_graph_enter(unsigned long ret, unsigned long func,
 	if (static_branch_likely(&fgraph_do_direct)) {
 		int save_curr_ret_stack = current->curr_ret_stack;
 
-		if (static_call(fgraph_func)(&trace, fgraph_direct_gops))
+		if (static_call(fgraph_func)(&trace, fgraph_direct_gops, &extras))
 			bitmap |= BIT(fgraph_direct_gops->idx);
 		else
 			/* Clear out any saved storage */
@@ -649,7 +658,7 @@  int function_graph_enter(unsigned long ret, unsigned long func,
 
 			save_curr_ret_stack = current->curr_ret_stack;
 			if (ftrace_ops_test(&gops->ops, func, NULL) &&
-			    gops->entryfunc(&trace, gops))
+			    gops->entryfunc(&trace, gops, &extras))
 				bitmap |= BIT(i);
 			else
 				/* Clear out any saved storage */
@@ -1119,7 +1128,8 @@  void ftrace_graph_exit_task(struct task_struct *t)
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 static int fgraph_pid_func(struct ftrace_graph_ent *trace,
-			   struct fgraph_ops *gops)
+			   struct fgraph_ops *gops,
+			   struct fgraph_extras *extras)
 {
 	struct trace_array *tr = gops->ops.private;
 	int pid;
@@ -1133,7 +1143,7 @@  static int fgraph_pid_func(struct ftrace_graph_ent *trace,
 			return 0;
 	}
 
-	return gops->saved_func(trace, gops);
+	return gops->saved_func(trace, gops, NULL);
 }
 
 void fgraph_update_pid_func(void)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 4c28dd177ca6..707ae465ed62 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -821,7 +821,8 @@  void ftrace_graph_graph_time_control(bool enable)
 }
 
 static int profile_graph_entry(struct ftrace_graph_ent *trace,
-			       struct fgraph_ops *gops)
+			       struct fgraph_ops *gops,
+			       struct fgraph_extras *extras)
 {
 	struct ftrace_ret_stack *ret_stack;
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index bd3e3069300e..2ab08d0bd4bc 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -46,6 +46,7 @@  enum trace_type {
 	TRACE_BRANCH,
 	TRACE_GRAPH_RET,
 	TRACE_GRAPH_ENT,
+	TRACE_GRAPH_RETADDR_ENT,
 	TRACE_USER_STACK,
 	TRACE_BLK,
 	TRACE_BPUTS,
@@ -505,6 +506,8 @@  extern void __ftrace_bad_type(void);
 		IF_ASSIGN(var, ent, struct trace_branch, TRACE_BRANCH); \
 		IF_ASSIGN(var, ent, struct ftrace_graph_ent_entry,	\
 			  TRACE_GRAPH_ENT);		\
+		IF_ASSIGN(var, ent, struct fgraph_retaddr_ent_entry,\
+			  TRACE_GRAPH_RETADDR_ENT);		\
 		IF_ASSIGN(var, ent, struct ftrace_graph_ret_entry,	\
 			  TRACE_GRAPH_RET);		\
 		IF_ASSIGN(var, ent, struct func_repeats_entry,		\
@@ -683,7 +686,8 @@  void trace_default_header(struct seq_file *m);
 void print_trace_header(struct seq_file *m, struct trace_iterator *iter);
 
 void trace_graph_return(struct ftrace_graph_ret *trace, struct fgraph_ops *gops);
-int trace_graph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);
+int trace_graph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops,
+		      struct fgraph_extras *extras);
 
 void tracing_start_cmdline_record(void);
 void tracing_stop_cmdline_record(void);
@@ -870,6 +874,7 @@  static __always_inline bool ftrace_hash_empty(struct ftrace_hash *hash)
 #define TRACE_GRAPH_GRAPH_TIME          0x400
 #define TRACE_GRAPH_PRINT_RETVAL        0x800
 #define TRACE_GRAPH_PRINT_RETVAL_HEX    0x1000
+#define TRACE_GRAPH_PRINT_RETADDR       0x2000
 #define TRACE_GRAPH_PRINT_FILL_SHIFT	28
 #define TRACE_GRAPH_PRINT_FILL_MASK	(0x3 << TRACE_GRAPH_PRINT_FILL_SHIFT)
 
@@ -891,6 +896,10 @@  extern void graph_trace_close(struct trace_iterator *iter);
 extern int __trace_graph_entry(struct trace_array *tr,
 			       struct ftrace_graph_ent *trace,
 			       unsigned int trace_ctx);
+extern int __trace_graph_retaddr_entry(struct trace_array *tr,
+				struct ftrace_graph_ent *trace,
+				unsigned int trace_ctx,
+				unsigned long retaddr);
 extern void __trace_graph_return(struct trace_array *tr,
 				 struct ftrace_graph_ret *trace,
 				 unsigned int trace_ctx);
diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h
index c47422b20908..82fd174ebbe0 100644
--- a/kernel/trace/trace_entries.h
+++ b/kernel/trace/trace_entries.h
@@ -85,9 +85,35 @@  FTRACE_ENTRY_PACKED(funcgraph_entry, ftrace_graph_ent_entry,
 	F_printk("--> %ps (%d)", (void *)__entry->func, __entry->depth)
 );
 
-/* Function return entry */
+#ifdef CONFIG_FUNCTION_GRAPH_RETADDR
+
+/* Function call entry with a return address */
+FTRACE_ENTRY_PACKED(fgraph_retaddr_entry, fgraph_retaddr_ent_entry,
+
+	TRACE_GRAPH_RETADDR_ENT,
+
+	F_STRUCT(
+		__field_struct(	struct fgraph_retaddr_ent,	graph_ent	)
+		__field_packed(	unsigned long,	graph_ent,	func		)
+		__field_packed(	int,		graph_ent,	depth		)
+		__field_packed(	unsigned long,	graph_ent,	retaddr		)
+	),
+
+	F_printk("--> %ps (%d) <- %ps", (void *)__entry->func, __entry->depth,
+		(void *)__entry->retaddr)
+);
+
+#else
+
+#ifndef fgraph_retaddr_ent_entry
+#define fgraph_retaddr_ent_entry ftrace_graph_ent_entry
+#endif
+
+#endif
+
 #ifdef CONFIG_FUNCTION_GRAPH_RETVAL
 
+/* Function return entry */
 FTRACE_ENTRY_PACKED(funcgraph_exit, ftrace_graph_ret_entry,
 
 	TRACE_GRAPH_RET,
@@ -110,6 +136,7 @@  FTRACE_ENTRY_PACKED(funcgraph_exit, ftrace_graph_ret_entry,
 
 #else
 
+/* Function return entry */
 FTRACE_ENTRY_PACKED(funcgraph_exit, ftrace_graph_ret_entry,
 
 	TRACE_GRAPH_RET,
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 13d0387ac6a6..ad9cba058d4d 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -31,7 +31,10 @@  struct fgraph_data {
 	struct fgraph_cpu_data __percpu *cpu_data;
 
 	/* Place to preserve last processed entry. */
-	struct ftrace_graph_ent_entry	ent;
+	union {
+		struct ftrace_graph_ent_entry	ent;
+		struct fgraph_retaddr_ent_entry	rent;
+	} ent;
 	struct ftrace_graph_ret_entry	ret;
 	int				failed;
 	int				cpu;
@@ -63,6 +66,10 @@  static struct tracer_opt trace_opts[] = {
 	{ TRACER_OPT(funcgraph-retval, TRACE_GRAPH_PRINT_RETVAL) },
 	/* Display function return value in hexadecimal format ? */
 	{ TRACER_OPT(funcgraph-retval-hex, TRACE_GRAPH_PRINT_RETVAL_HEX) },
+#endif
+#ifdef CONFIG_FUNCTION_GRAPH_RETADDR
+	/* Display function return address ? */
+	{ TRACER_OPT(funcgraph-retaddr, TRACE_GRAPH_PRINT_RETADDR) },
 #endif
 	/* Include sleep time (scheduled out) between entry and return */
 	{ TRACER_OPT(sleep-time, TRACE_GRAPH_SLEEP_TIME) },
@@ -83,6 +90,11 @@  static struct tracer_flags tracer_flags = {
 	.opts = trace_opts
 };
 
+u32 graph_tracer_flags_get(u32 flags)
+{
+	return tracer_flags.val & flags;
+}
+
 /*
  * DURATION column is being also used to display IRQ signs,
  * following values are used by print_graph_irq and others
@@ -119,6 +131,40 @@  int __trace_graph_entry(struct trace_array *tr,
 	return 1;
 }
 
+#ifdef CONFIG_FUNCTION_GRAPH_RETADDR
+int __trace_graph_retaddr_entry(struct trace_array *tr,
+				struct ftrace_graph_ent *trace,
+				unsigned int trace_ctx,
+				unsigned long retaddr)
+{
+	struct trace_event_call *call = &event_fgraph_retaddr_entry;
+	struct ring_buffer_event *event;
+	struct trace_buffer *buffer = tr->array_buffer.buffer;
+	struct fgraph_retaddr_ent_entry *entry;
+
+	event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_RETADDR_ENT,
+					  sizeof(*entry), trace_ctx);
+	if (!event)
+		return 0;
+	entry	= ring_buffer_event_data(event);
+	entry->graph_ent.func = trace->func;
+	entry->graph_ent.depth = trace->depth;
+	entry->graph_ent.retaddr = retaddr;
+	if (!call_filter_check_discard(call, entry, buffer, event))
+		trace_buffer_unlock_commit_nostack(buffer, event);
+
+	return 1;
+}
+#else
+int __trace_graph_retaddr_entry(struct trace_array *tr,
+				struct ftrace_graph_ent *trace,
+				unsigned int trace_ctx,
+				unsigned long retaddr)
+{
+	return 1;
+}
+#endif
+
 static inline int ftrace_graph_ignore_irqs(void)
 {
 	if (!ftrace_graph_skip_irqs || trace_recursion_test(TRACE_IRQ_BIT))
@@ -128,7 +174,8 @@  static inline int ftrace_graph_ignore_irqs(void)
 }
 
 int trace_graph_entry(struct ftrace_graph_ent *trace,
-		      struct fgraph_ops *gops)
+		      struct fgraph_ops *gops,
+		      struct fgraph_extras *extras)
 {
 	unsigned long *task_var = fgraph_get_task_var(gops);
 	struct trace_array *tr = gops->private;
@@ -180,7 +227,12 @@  int trace_graph_entry(struct ftrace_graph_ent *trace,
 	disabled = atomic_inc_return(&data->disabled);
 	if (likely(disabled == 1)) {
 		trace_ctx = tracing_gen_ctx_flags(flags);
-		ret = __trace_graph_entry(tr, trace, trace_ctx);
+		if (unlikely(IS_ENABLED(CONFIG_FUNCTION_GRAPH_RETADDR) && extras
+				&& (extras->flags & TRACE_GRAPH_PRINT_RETADDR)))
+			ret = __trace_graph_retaddr_entry(tr, trace, trace_ctx,
+							  extras->retaddr);
+		else
+			ret = __trace_graph_entry(tr, trace, trace_ctx);
 	} else {
 		ret = 0;
 	}
@@ -457,7 +509,7 @@  get_return_for_leaf(struct trace_iterator *iter,
 	 * then we just reuse the data from before.
 	 */
 	if (data && data->failed) {
-		curr = &data->ent;
+		curr = &data->ent.ent;
 		next = &data->ret;
 	} else {
 
@@ -487,7 +539,10 @@  get_return_for_leaf(struct trace_iterator *iter,
 			 * Save current and next entries for later reference
 			 * if the output fails.
 			 */
-			data->ent = *curr;
+			if (unlikely(curr->ent.type == TRACE_GRAPH_RETADDR_ENT))
+				data->ent.rent = *(struct fgraph_retaddr_ent_entry *)curr;
+			else
+				data->ent.ent = *curr;
 			/*
 			 * If the next event is not a return type, then
 			 * we only care about what type it is. Otherwise we can
@@ -649,52 +704,97 @@  print_graph_duration(struct trace_array *tr, unsigned long long duration,
 }
 
 #ifdef CONFIG_FUNCTION_GRAPH_RETVAL
-
 #define __TRACE_GRAPH_PRINT_RETVAL TRACE_GRAPH_PRINT_RETVAL
+#else
+#define __TRACE_GRAPH_PRINT_RETVAL 0
+#endif
+
+#ifdef CONFIG_FUNCTION_GRAPH_RETADDR
+#define __TRACE_GRAPH_PRINT_RETADDR TRACE_GRAPH_PRINT_RETADDR
+static void print_graph_retaddr(struct trace_seq *s, struct fgraph_retaddr_ent_entry *entry,
+				u32 trace_flags, bool comment)
+{
+	if (comment)
+		trace_seq_puts(s, " /*");
+
+	trace_seq_puts(s, " <-");
+	seq_print_ip_sym(s, entry->graph_ent.retaddr, trace_flags | TRACE_ITER_SYM_OFFSET);
+
+	if (comment)
+		trace_seq_puts(s, " */");
+}
+#else
+#define __TRACE_GRAPH_PRINT_RETADDR 0
+#define print_graph_retaddr(_seq, _entry, _tflags, _comment)		do { } while (0)
+#endif
 
-static void print_graph_retval(struct trace_seq *s, unsigned long retval,
-				bool leaf, void *func, bool hex_format)
+#if defined(CONFIG_FUNCTION_GRAPH_RETVAL) || defined(CONFIG_FUNCTION_GRAPH_RETADDR)
+
+static void print_graph_retval(struct trace_seq *s, struct ftrace_graph_ent_entry *entry,
+				struct ftrace_graph_ret *graph_ret,
+				u32 opt_flags, u32 trace_flags)
 {
 	unsigned long err_code = 0;
+	unsigned long retval = 0;
+	bool print_retaddr = false;
+	bool print_retval = false;
+	bool hex_format = !!(opt_flags & TRACE_GRAPH_PRINT_RETVAL_HEX);
+	void *func = (void *)graph_ret->func;
+
+#ifdef CONFIG_FUNCTION_GRAPH_RETVAL
+	retval = graph_ret->retval;
+	print_retval = !!(opt_flags & TRACE_GRAPH_PRINT_RETVAL);
+#endif
 
-	if (retval == 0 || hex_format)
-		goto done;
+#ifdef CONFIG_FUNCTION_GRAPH_RETADDR
+	print_retaddr = !!(opt_flags & TRACE_GRAPH_PRINT_RETADDR);
+#endif
 
-	/* Check if the return value matches the negative format */
-	if (IS_ENABLED(CONFIG_64BIT) && (retval & BIT(31)) &&
-		(((u64)retval) >> 32) == 0) {
-		/* sign extension */
-		err_code = (unsigned long)(s32)retval;
-	} else {
-		err_code = retval;
+	if (print_retval && retval && !hex_format) {
+		/* Check if the return value matches the negative format */
+		if (IS_ENABLED(CONFIG_64BIT) && (retval & BIT(31)) &&
+			(((u64)retval) >> 32) == 0) {
+			err_code = sign_extend64(retval, 31);
+		} else {
+			err_code = retval;
+		}
+
+		if (!IS_ERR_VALUE(err_code))
+			err_code = 0;
 	}
 
-	if (!IS_ERR_VALUE(err_code))
-		err_code = 0;
+	if (entry) {
+		if (entry->ent.type != TRACE_GRAPH_RETADDR_ENT)
+			print_retaddr = false;
 
-done:
-	if (leaf) {
-		if (hex_format || (err_code == 0))
-			trace_seq_printf(s, "%ps(); /* = 0x%lx */\n",
-					func, retval);
+		trace_seq_printf(s, "%ps();", func);
+		if (print_retval || print_retaddr)
+			trace_seq_puts(s, " /*");
 		else
-			trace_seq_printf(s, "%ps(); /* = %ld */\n",
-					func, err_code);
+			trace_seq_putc(s, '\n');
 	} else {
+		print_retaddr = false;
+		trace_seq_printf(s, "} /* %ps", func);
+	}
+
+	if (print_retaddr)
+		print_graph_retaddr(s, (struct fgraph_retaddr_ent_entry *)entry,
+				    trace_flags, false);
+
+	if (print_retval) {
 		if (hex_format || (err_code == 0))
-			trace_seq_printf(s, "} /* %ps = 0x%lx */\n",
-					func, retval);
+			trace_seq_printf(s, " ret=0x%lx", retval);
 		else
-			trace_seq_printf(s, "} /* %ps = %ld */\n",
-					func, err_code);
+			trace_seq_printf(s, " ret=%ld", err_code);
 	}
+
+	if (!entry || print_retval || print_retaddr)
+		trace_seq_puts(s, " */\n");
 }
 
 #else
 
-#define __TRACE_GRAPH_PRINT_RETVAL 0
-
-#define print_graph_retval(_seq, _retval, _leaf, _func, _format) do {} while (0)
+#define print_graph_retval(_seq, _ent, _ret, _opt_flags, _trace_flags) do {} while (0)
 
 #endif
 
@@ -743,12 +843,10 @@  print_graph_entry_leaf(struct trace_iterator *iter,
 		trace_seq_putc(s, ' ');
 
 	/*
-	 * Write out the function return value if the option function-retval is
-	 * enabled.
+	 * Write out the function return value or return address
 	 */
-	if (flags & __TRACE_GRAPH_PRINT_RETVAL)
-		print_graph_retval(s, graph_ret->retval, true, (void *)call->func,
-				!!(flags & TRACE_GRAPH_PRINT_RETVAL_HEX));
+	if (flags & (__TRACE_GRAPH_PRINT_RETVAL | __TRACE_GRAPH_PRINT_RETADDR))
+		print_graph_retval(s, entry, graph_ret, flags, tr->trace_flags);
 	else
 		trace_seq_printf(s, "%ps();\n", (void *)call->func);
 
@@ -788,7 +886,12 @@  print_graph_entry_nested(struct trace_iterator *iter,
 	for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
 		trace_seq_putc(s, ' ');
 
-	trace_seq_printf(s, "%ps() {\n", (void *)call->func);
+	trace_seq_printf(s, "%ps() {", (void *)call->func);
+	if (flags & __TRACE_GRAPH_PRINT_RETADDR  &&
+		entry->ent.type == TRACE_GRAPH_RETADDR_ENT)
+		print_graph_retaddr(s, (struct fgraph_retaddr_ent_entry *)entry,
+			tr->trace_flags, true);
+	trace_seq_putc(s, '\n');
 
 	if (trace_seq_has_overflowed(s))
 		return TRACE_TYPE_PARTIAL_LINE;
@@ -1030,11 +1133,10 @@  print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
 
 	/*
 	 * Always write out the function name and its return value if the
-	 * function-retval option is enabled.
+	 * funcgraph-retval option is enabled.
 	 */
 	if (flags & __TRACE_GRAPH_PRINT_RETVAL) {
-		print_graph_retval(s, trace->retval, false, (void *)trace->func,
-			!!(flags & TRACE_GRAPH_PRINT_RETVAL_HEX));
+		print_graph_retval(s, NULL, trace, flags, tr->trace_flags);
 	} else {
 		/*
 		 * If the return function does not have a matching entry,
@@ -1149,7 +1251,7 @@  print_graph_function_flags(struct trace_iterator *iter, u32 flags)
 	 * to print out the missing entry which would never go out.
 	 */
 	if (data && data->failed) {
-		field = &data->ent;
+		field = &data->ent.ent;
 		iter->cpu = data->cpu;
 		ret = print_graph_entry(field, s, iter, flags);
 		if (ret == TRACE_TYPE_HANDLED && iter->cpu != cpu) {
@@ -1173,6 +1275,16 @@  print_graph_function_flags(struct trace_iterator *iter, u32 flags)
 		saved = *field;
 		return print_graph_entry(&saved, s, iter, flags);
 	}
+#ifdef CONFIG_FUNCTION_GRAPH_RETADDR
+	case TRACE_GRAPH_RETADDR_ENT: {
+		struct fgraph_retaddr_ent_entry saved;
+		struct fgraph_retaddr_ent_entry *rfield;
+
+		trace_assign_type(rfield, entry);
+		saved = *rfield;
+		return print_graph_entry((struct ftrace_graph_ent_entry *)&saved, s, iter, flags);
+	}
+#endif
 	case TRACE_GRAPH_RET: {
 		struct ftrace_graph_ret_entry *field;
 		trace_assign_type(field, entry);
@@ -1367,6 +1479,13 @@  static struct trace_event graph_trace_entry_event = {
 	.funcs		= &graph_functions,
 };
 
+#ifdef CONFIG_FUNCTION_GRAPH_RETADDR
+static struct trace_event graph_trace_retaddr_entry_event = {
+	.type		= TRACE_GRAPH_RETADDR_ENT,
+	.funcs		= &graph_functions,
+};
+#endif
+
 static struct trace_event graph_trace_ret_event = {
 	.type		= TRACE_GRAPH_RET,
 	.funcs		= &graph_functions
@@ -1453,6 +1572,13 @@  static __init int init_graph_trace(void)
 		return 1;
 	}
 
+#ifdef CONFIG_FUNCTION_GRAPH_RETADDR
+	if (!register_trace_event(&graph_trace_retaddr_entry_event)) {
+		pr_warn("Warning: could not register graph trace retaddr events\n");
+		return 1;
+	}
+#endif
+
 	if (!register_trace_event(&graph_trace_ret_event)) {
 		pr_warn("Warning: could not register graph trace events\n");
 		return 1;
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index fce064e20570..eb3aa36cf10f 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -176,7 +176,8 @@  static int irqsoff_display_graph(struct trace_array *tr, int set)
 }
 
 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace,
-			       struct fgraph_ops *gops)
+			       struct fgraph_ops *gops,
+			       struct fgraph_extras *extras)
 {
 	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 130ca7e7787e..742b9de14ddb 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -113,7 +113,8 @@  static int wakeup_display_graph(struct trace_array *tr, int set)
 }
 
 static int wakeup_graph_entry(struct ftrace_graph_ent *trace,
-			      struct fgraph_ops *gops)
+			      struct fgraph_ops *gops,
+			      struct fgraph_extras *extras)
 {
 	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 c4ad7cd7e778..fbb99f8c8062 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -17,6 +17,7 @@  static inline int trace_valid_entry(struct trace_entry *entry)
 	case TRACE_PRINT:
 	case TRACE_BRANCH:
 	case TRACE_GRAPH_ENT:
+	case TRACE_GRAPH_RETADDR_ENT:
 	case TRACE_GRAPH_RET:
 		return 1;
 	}
@@ -773,7 +774,8 @@  struct fgraph_fixture {
 };
 
 static __init int store_entry(struct ftrace_graph_ent *trace,
-			      struct fgraph_ops *gops)
+			      struct fgraph_ops *gops,
+			      struct fgraph_extras *extras)
 {
 	struct fgraph_fixture *fixture = container_of(gops, struct fgraph_fixture, gops);
 	const char *type = fixture->store_type_name;
@@ -1024,7 +1026,8 @@  static unsigned int graph_hang_thresh;
 
 /* Wrap the real function entry probe to avoid possible hanging */
 static int trace_graph_entry_watchdog(struct ftrace_graph_ent *trace,
-				      struct fgraph_ops *gops)
+				      struct fgraph_ops *gops,
+				      struct fgraph_extras *extras)
 {
 	/* This is harmlessly racy, we want to approximately detect a hang */
 	if (unlikely(++graph_hang_thresh > GRAPH_MAX_FUNC_TEST)) {
@@ -1038,7 +1041,7 @@  static int trace_graph_entry_watchdog(struct ftrace_graph_ent *trace,
 		return 0;
 	}
 
-	return trace_graph_entry(trace, gops);
+	return trace_graph_entry(trace, gops, NULL);
 }
 
 static struct fgraph_ops fgraph_ops __initdata  = {
diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-retval.tc b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-retval.tc
index e34c0bdef3ed..e8e46378b88d 100644
--- a/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-retval.tc
+++ b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-retval.tc
@@ -29,7 +29,7 @@  set -e
 
 : "Test printing the error code in signed decimal format"
 echo 0 > options/funcgraph-retval-hex
-count=`cat trace | grep 'proc_reg_write' | grep '= -5' | wc -l`
+count=`cat trace | grep 'proc_reg_write' | grep '=-5' | wc -l`
 if [ $count -eq 0 ]; then
     fail "Return value can not be printed in signed decimal format"
 fi