2018-11-22 12:15:57

by Steven Rostedt

Subject: [for-next][PATCH 10/18] riscv/function_graph: Simplify with function_graph_entry()

From: "Steven Rostedt (VMware)" <[email protected]>

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 riscv 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: Greentime Hu <[email protected]>
Cc: Alan Kao <[email protected]>
Cc: Palmer Dabbelt <[email protected]>
Cc: [email protected]
Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Signed-off-by: Steven Rostedt (VMware) <[email protected]>
---
arch/riscv/kernel/ftrace.c | 14 ++------------
1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
index 1157b6b52d25..c433f6d3dd64 100644
--- a/arch/riscv/kernel/ftrace.c
+++ b/arch/riscv/kernel/ftrace.c
@@ -132,7 +132,6 @@ 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)))
@@ -144,17 +143,8 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
*/
old = *parent;

- trace.func = self_addr;
- trace.depth = current->curr_ret_stack + 1;
-
- if (!ftrace_graph_entry(&trace))
- return;
-
- err = ftrace_push_return_trace(old, self_addr, &trace.depth,
- frame_pointer, parent);
- if (err == -EBUSY)
- return;
- *parent = return_hooker;
+ if (function_graph_enter(old, self_addr, frame_pointer, parent))
+ *parent = return_hooker;
}

#ifdef CONFIG_DYNAMIC_FTRACE
--
2.19.1

2018-11-26 16:50:08

by Palmer Dabbelt

Subject: Re: [for-next][PATCH 10/18] riscv/function_graph: Simplify with function_graph_entry()

On Wed, 21 Nov 2018 16:28:11 PST (-0800), [email protected] wrote:
> From: "Steven Rostedt (VMware)" <[email protected]>
>
> 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 riscv 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: Greentime Hu <[email protected]>
> Cc: Alan Kao <[email protected]>
> Cc: Palmer Dabbelt <[email protected]>
> Cc: [email protected]
> Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
> Signed-off-by: Steven Rostedt (VMware) <[email protected]>
> ---
> arch/riscv/kernel/ftrace.c | 14 ++------------
> 1 file changed, 2 insertions(+), 12 deletions(-)
>
> diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
> index 1157b6b52d25..c433f6d3dd64 100644
> --- a/arch/riscv/kernel/ftrace.c
> +++ b/arch/riscv/kernel/ftrace.c
> @@ -132,7 +132,6 @@ 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)))
> @@ -144,17 +143,8 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
> */
> old = *parent;
>
> - trace.func = self_addr;
> - trace.depth = current->curr_ret_stack + 1;
> -
> - if (!ftrace_graph_entry(&trace))
> - return;
> -
> - err = ftrace_push_return_trace(old, self_addr, &trace.depth,
> - frame_pointer, parent);
> - if (err == -EBUSY)
> - return;
> - *parent = return_hooker;
> + if (function_graph_enter(old, self_addr, frame_pointer, parent))
> + *parent = return_hooker;
> }
>
> #ifdef CONFIG_DYNAMIC_FTRACE

Reviewed-by: Palmer Dabbelt <[email protected]>