The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 01e0ab2c4ff12358f15a856fd1a7bbea0670972b Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (VMware)" rostedt@goodmis.org Date: Sun, 18 Nov 2018 17:21:51 -0500 Subject: [PATCH] arm64: function_graph: Simplify with function_graph_enter()
The function_graph_enter() 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: linux-arm-kernel@lists.infradead.org Cc: stable@kernel.org Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback") Acked-by: Will Deacon will.deacon@arm.com Reviewed-by: Masami Hiramatsu mhiramat@kernel.org Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org
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(¤t->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; }