diff mbox series

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

Message ID 20181122003331.917870132@goodmis.org (mailing list archive)
State New, archived
Headers show
Series None | expand

Commit Message

Steven Rostedt Nov. 22, 2018, 12:28 a.m. UTC 
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@lists.infradead.org
Cc: stable@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(-)

Comments

Will Deacon Nov. 27, 2018, 6:07 p.m. UTC | #1 
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@lists.infradead.org
> Cc: stable@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
Steven Rostedt Nov. 27, 2018, 6:26 p.m. UTC | #2 
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@lists.infradead.org
> > Cc: stable@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
diff mbox series

Patch

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;
 }