[for-next][PATCH 05/24] powerpc/frace: Use ftrace_graph_get_ret_stack() instead of curr_ret_stack

[for-next][PATCH 05/24] powerpc/frace: Use ftrace_graph_get_ret_stack() instead of curr_ret_stack

[Steven Rostedt]

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

The structure of the ret_stack array on the task struct is going to
change, and accessing it directly via the curr_ret_stack index will no
longer give the ret_stack entry that holds the return address. To access
that, architectures must now use ftrace_graph_get_ret_stack() to get the
associated ret_stack that matches the saved return address.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 arch/powerpc/kernel/process.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 96f34730010f..ce393df243aa 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -2061,9 +2061,10 @@ void show_stack(struct task_struct *tsk, unsigned long *stack)
 	int count = 0;
 	int firstframe = 1;
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	int curr_frame = current->curr_ret_stack;
+	struct ftrace_ret_stack *ret_stack;
 	extern void return_to_handler(void);
 	unsigned long rth = (unsigned long)return_to_handler;
+	int curr_frame = 0;
 #endif
 
 	sp = (unsigned long) stack;
@@ -2089,9 +2090,13 @@ void show_stack(struct task_struct *tsk, unsigned long *stack)
 			printk("["REG"] ["REG"] %pS", sp, ip, (void *)ip);
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 			if ((ip == rth) && curr_frame >= 0) {
-				pr_cont(" (%pS)",
-				       (void *)current->ret_stack[curr_frame].ret);
-				curr_frame--;
+				ret_stack = ftrace_graph_get_ret_stack(current,
+								  curr_frame++);
+				if (ret_stack)
+					pr_cont(" (%pS)",
+						(void *)ret_stack->ret);
+				else
+					curr_frame = -1;
 			}
 #endif
 			if (firstframe)
-- 
2.19.2

Re: [for-next][PATCH 05/24] powerpc/frace: Use ftrace_graph_get_ret_stack() instead of curr_ret_stack

[Michael Ellerman]

Steven Rostedt <rostedt@goodmis.org> writes:

> From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
>
> The structure of the ret_stack array on the task struct is going to
> change, and accessing it directly via the curr_ret_stack index will no
> longer give the ret_stack entry that holds the return address. To access
> that, architectures must now use ftrace_graph_get_ret_stack() to get the
> associated ret_stack that matches the saved return address.
>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: linuxppc-dev@lists.ozlabs.org
> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> ---
>  arch/powerpc/kernel/process.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)

I did test the previous series you posted and I think everything was OK
running the ftracetest suite (I got one or two fails but I think that
was because of missing CONFIG options).

Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

cheers

Re: [for-next][PATCH 05/24] powerpc/frace: Use ftrace_graph_get_ret_stack() instead of curr_ret_stack

[Steven Rostedt]

On Sat, 22 Dec 2018 20:51:21 +1100
Michael Ellerman <mpe@ellerman.id.au> wrote:


> I did test the previous series you posted and I think everything was OK
> running the ftracetest suite (I got one or two fails but I think that
> was because of missing CONFIG options).
> 
> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

Thanks! I'll add your ack.

-- Steve