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

Commit Message

Steven Rostedt Nov. 22, 2018, 12:28 a.m. UTC

From: "Steven Rostedt (VMware)" <[e-mail]>

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 <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Signed-off-by: Steven Rostedt (VMware) <[e-mail]>
---
 arch/arm/kernel/ftrace.c | 17 +----------------
 1 file changed, 1 insertion(+), 16 deletions(-)

Comments

Sasha Levin Nov. 23, 2018, 7:30 a.m. UTC | #1

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

Patch

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