[for-next][PATCH 03/18] ARM: function_graph: Simplify with function_graph_entry()

[for-next][PATCH 03/18] ARM: function_graph: Simplify with function_graph_entry()

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

The function_graph_entry() function does the work of calling the function
graph hook function and the management of the shadow stack, simplifying the
work done in the architecture dependent prepare_ftrace_return().

Have ARM use the new code, and remove the shadow stack management as well as
having to set up the trace structure.

This is needed to prepare for a fix of a design bug on how the curr_ret_stack
is used.

Cc: Russell King <linux@armlinux.org.uk>
Cc: linux-arm-kernel at lists.infradead.org
Cc: stable at kernel.org
Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 arch/arm/kernel/ftrace.c | 17 +----------------
 1 file changed, 1 insertion(+), 16 deletions(-)

diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index 0142fcfcc3d3..bda949fd84e8 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -183,9 +183,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 			   unsigned long frame_pointer)
 {
 	unsigned long return_hooker = (unsigned long) &return_to_handler;
-	struct ftrace_graph_ent trace;
 	unsigned long old;
-	int err;
 
 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
 		return;
@@ -193,21 +191,8 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 	old = *parent;
 	*parent = return_hooker;
 
-	trace.func = self_addr;
-	trace.depth = current->curr_ret_stack + 1;
-
-	/* Only trace if the calling function expects to */
-	if (!ftrace_graph_entry(&trace)) {
+	if (function_graph_enter(old, self_addr, frame_pointer, NULL))
 		*parent = old;
-		return;
-	}
-
-	err = ftrace_push_return_trace(old, self_addr, &trace.depth,
-				       frame_pointer, NULL);
-	if (err == -EBUSY) {
-		*parent = old;
-		return;
-	}
 }
 
 #ifdef CONFIG_DYNAMIC_FTRACE
-- 
2.19.1

[for-next][PATCH 03/18] ARM: function_graph: Simplify with function_graph_entry()

[Sasha Levin]

Hi,

[This is an automated email]

This commit has been processed because it contains a "Fixes:" tag,
fixing commit: 03274a3ffb44 tracing/fgraph: Adjust fgraph depth before calling trace return callback.

The bot has tested the following trees: v4.19.3, v4.14.82, v4.9.138, v4.4.164, v3.18.126.

v4.19.3: Build OK!
v4.14.82: Build OK!
v4.9.138: Build OK!
v4.4.164: Failed to apply! Possible dependencies:
    Unable to calculate

v3.18.126: Failed to apply! Possible dependencies:
    Unable to calculate


How should we proceed with this patch?

--
Thanks,
Sasha

[for-next][PATCH 04/18] arm64: function_graph: Simplify with function_graph_entry()

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

The function_graph_entry() function does the work of calling the function
graph hook function and the management of the shadow stack, simplifying the
work done in the architecture dependent prepare_ftrace_return().

Have arm64 use the new code, and remove the shadow stack management as well as
having to set up the trace structure.

This is needed to prepare for a fix of a design bug on how the curr_ret_stack
is used.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel at lists.infradead.org
Cc: stable at kernel.org
Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 arch/arm64/kernel/ftrace.c | 15 +--------------
 1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index 50986e388d2b..57e962290df3 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -216,8 +216,6 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 {
 	unsigned long return_hooker = (unsigned long)&return_to_handler;
 	unsigned long old;
-	struct ftrace_graph_ent trace;
-	int err;
 
 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
 		return;
@@ -229,18 +227,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 	 */
 	old = *parent;
 
-	trace.func = self_addr;
-	trace.depth = current->curr_ret_stack + 1;
-
-	/* Only trace if the calling function expects to */
-	if (!ftrace_graph_entry(&trace))
-		return;
-
-	err = ftrace_push_return_trace(old, self_addr, &trace.depth,
-				       frame_pointer, NULL);
-	if (err == -EBUSY)
-		return;
-	else
+	if (!function_graph_enter(old, self_addr, frame_pointer, NULL))
 		*parent = return_hooker;
 }
 
-- 
2.19.1

[for-next][PATCH 04/18] arm64: function_graph: Simplify with function_graph_entry()

[Will Deacon]

On Wed, Nov 21, 2018 at 07:28:05PM -0500, Steven Rostedt wrote:
> From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
> 
> The function_graph_entry() function does the work of calling the function
> graph hook function and the management of the shadow stack, simplifying the
> work done in the architecture dependent prepare_ftrace_return().
> 
> Have arm64 use the new code, and remove the shadow stack management as well as
> having to set up the trace structure.
> 
> This is needed to prepare for a fix of a design bug on how the curr_ret_stack
> is used.
> 
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: linux-arm-kernel at lists.infradead.org
> Cc: stable at kernel.org
> Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> ---
>  arch/arm64/kernel/ftrace.c | 15 +--------------
>  1 file changed, 1 insertion(+), 14 deletions(-)

Minor nit: the subject refers to function_graph_entry(), but looks like
you settled on function_graph_enter() in the end.

Anyway, looks like no change for us, so:

Acked-by: Will Deacon <will.deacon@arm.com>

Will

[for-next][PATCH 04/18] arm64: function_graph: Simplify with function_graph_entry()

[Steven Rostedt]

On Tue, 27 Nov 2018 18:07:23 +0000
Will Deacon <will.deacon@arm.com> wrote:

> On Wed, Nov 21, 2018 at 07:28:05PM -0500, Steven Rostedt wrote:
> > From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
> > 
> > The function_graph_entry() function does the work of calling the function
> > graph hook function and the management of the shadow stack, simplifying the
> > work done in the architecture dependent prepare_ftrace_return().
> > 
> > Have arm64 use the new code, and remove the shadow stack management as well as
> > having to set up the trace structure.
> > 
> > This is needed to prepare for a fix of a design bug on how the curr_ret_stack
> > is used.
> > 
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: Will Deacon <will.deacon@arm.com>
> > Cc: linux-arm-kernel at lists.infradead.org
> > Cc: stable at kernel.org
> > Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
> > Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> > ---
> >  arch/arm64/kernel/ftrace.c | 15 +--------------
> >  1 file changed, 1 insertion(+), 14 deletions(-)  
> 
> Minor nit: the subject refers to function_graph_entry(), but looks like
> you settled on function_graph_enter() in the end.

Ah you're right!

> 
> Anyway, looks like no change for us, so:
> 
> Acked-by: Will Deacon <will.deacon@arm.com>

Thanks!

-- Steve