From: Steven Rostedt (VMware) Date: Tue, 18 Dec 2018 20:50:02 +0000 (-0500) Subject: tracing: Fix ftrace_graph_get_ret_stack() to use task and not current X-Git-Tag: v5.4-rc1~1850^2~17 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e8d086ddb5339d72c60e6c7b8d28810f26960f9a;p=platform%2Fkernel%2Flinux-rpi.git tracing: Fix ftrace_graph_get_ret_stack() to use task and not current The function ftrace_graph_get_ret_stack() takes a task struct descriptor but uses current as the task to perform the operations on. In pretty much all cases the task decriptor is the same as current, so this wasn't an issue. But there is a case in the ARM architecture that passes in a task that is not current, and expects a result from that task, and this code breaks it. Fixes: 51584396cff5 ("arm64: Use ftrace_graph_get_ret_stack() instead of curr_ret_stack") Reported-by: James Morse Tested-by: James Morse Signed-off-by: Steven Rostedt (VMware) --- diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index d4f04f0..8dfd502 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -246,10 +246,10 @@ unsigned long ftrace_return_to_handler(unsigned long frame_pointer) struct ftrace_ret_stack * ftrace_graph_get_ret_stack(struct task_struct *task, int idx) { - idx = current->curr_ret_stack - idx; + idx = task->curr_ret_stack - idx; if (idx >= 0 && idx <= task->curr_ret_stack) - return ¤t->ret_stack[idx]; + return &task->ret_stack[idx]; return NULL; }