fgraph: Create a fgraph.c file to store function graph infrastructure

As the function graph infrastructure can be used by thing other than
tracing, moving the code to its own file out of the trace_functions_graph.c
code makes more sense.

The fgraph.c file will only contain the infrastructure required to hook into
functions and their return code.

Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 0 insertions, 220 deletions

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 0d235e44d08e..b846d82c2f95 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -16,33 +16,6 @@
 #include "trace.h"
 #include "trace_output.h"
 
-static bool kill_ftrace_graph;
-
-/**
- * ftrace_graph_is_dead - returns true if ftrace_graph_stop() was called
- *
- * ftrace_graph_stop() is called when a severe error is detected in
- * the function graph tracing. This function is called by the critical
- * paths of function graph to keep those paths from doing any more harm.
- */
-bool ftrace_graph_is_dead(void)
-{
-        return kill_ftrace_graph;
-}
-
-/**
- * ftrace_graph_stop - set to permanently disable function graph tracincg
- *
- * In case of an error int function graph tracing, this is called
- * to try to keep function graph tracing from causing any more harm.
- * Usually this is pretty severe and this is called to try to at least
- * get a warning out to the user.
- */
-void ftrace_graph_stop(void)
-{
-        kill_ftrace_graph = true;
-}
-
 /* When set, irq functions will be ignored */
 static int ftrace_graph_skip_irqs;
 
@@ -117,199 +90,6 @@ static void
 print_graph_duration(struct trace_array *tr, unsigned long long duration,
                      struct trace_seq *s, u32 flags);
 
-/* Add a function return address to the trace stack on thread info.*/
-static int
-ftrace_push_return_trace(unsigned long ret, unsigned long func,
-                         unsigned long frame_pointer, unsigned long *retp)
-{
-        unsigned long long calltime;
-        int index;
-
-        if (unlikely(ftrace_graph_is_dead()))
-                return -EBUSY;
-
-        if (!current->ret_stack)
-                return -EBUSY;
-
-        /*
-         * We must make sure the ret_stack is tested before we read
-         * anything else.
-         */
-        smp_rmb();
-
-        /* The return trace stack is full */
-        if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
-                atomic_inc(&current->trace_overrun);
-                return -EBUSY;
-        }
-
-        /*
-         * The curr_ret_stack is an index to ftrace return stack of
-         * current task.  Its value should be in [0, FTRACE_RETFUNC_
-         * DEPTH) when the function graph tracer is used.  To support
-         * filtering out specific functions, it makes the index
-         * negative by subtracting huge value (FTRACE_NOTRACE_DEPTH)
-         * so when it sees a negative index the ftrace will ignore
-         * the record.  And the index gets recovered when returning
-         * from the filtered function by adding the FTRACE_NOTRACE_
-         * DEPTH and then it'll continue to record functions normally.
-         *
-         * The curr_ret_stack is initialized to -1 and get increased
-         * in this function.  So it can be less than -1 only if it was
-         * filtered out via ftrace_graph_notrace_addr() which can be
-         * set from set_graph_notrace file in tracefs by user.
-         */
-        if (current->curr_ret_stack < -1)
-                return -EBUSY;
-
-        calltime = trace_clock_local();
-
-        index = ++current->curr_ret_stack;
-        if (ftrace_graph_notrace_addr(func))
-                current->curr_ret_stack -= FTRACE_NOTRACE_DEPTH;
-        barrier();
-        current->ret_stack[index].ret = ret;
-        current->ret_stack[index].func = func;
-        current->ret_stack[index].calltime = calltime;
-#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
-        current->ret_stack[index].fp = frame_pointer;
-#endif
-#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
-        current->ret_stack[index].retp = retp;
-#endif
-        return 0;
-}
-
-int function_graph_enter(unsigned long ret, unsigned long func,
-                         unsigned long frame_pointer, unsigned long *retp)
-{
-        struct ftrace_graph_ent trace;
-
-        trace.func = func;
-        trace.depth = ++current->curr_ret_depth;
-
-        if (ftrace_push_return_trace(ret, func, frame_pointer, retp))
-                goto out;
-
-        /* Only trace if the calling function expects to */
-        if (!ftrace_graph_entry(&trace))
-                goto out_ret;
-
-        return 0;
- out_ret:
-        current->curr_ret_stack--;
- out:
-        current->curr_ret_depth--;
-        return -EBUSY;
-}
-
-/* Retrieve a function return address to the trace stack on thread info.*/
-static void
-ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
-                        unsigned long frame_pointer)
-{
-        int index;
-
-        index = current->curr_ret_stack;
-
-        /*
-         * A negative index here means that it's just returned from a
-         * notrace'd function.  Recover index to get an original
-         * return address.  See ftrace_push_return_trace().
-         *
-         * TODO: Need to check whether the stack gets corrupted.
-         */
-        if (index < 0)
-                index += FTRACE_NOTRACE_DEPTH;
-
-        if (unlikely(index < 0 || index >= FTRACE_RETFUNC_DEPTH)) {
-                ftrace_graph_stop();
-                WARN_ON(1);
-                /* Might as well panic, otherwise we have no where to go */
-                *ret = (unsigned long)panic;
-                return;
-        }
-
-#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
-        /*
-         * The arch may choose to record the frame pointer used
-         * and check it here to make sure that it is what we expect it
-         * to be. If gcc does not set the place holder of the return
-         * address in the frame pointer, and does a copy instead, then
-         * the function graph trace will fail. This test detects this
-         * case.
-         *
-         * Currently, x86_32 with optimize for size (-Os) makes the latest
-         * gcc do the above.
-         *
-         * Note, -mfentry does not use frame pointers, and this test
-         *  is not needed if CC_USING_FENTRY is set.
-         */
-        if (unlikely(current->ret_stack[index].fp != frame_pointer)) {
-                ftrace_graph_stop();
-                WARN(1, "Bad frame pointer: expected %lx, received %lx\n"
-                     "  from func %ps return to %lx\n",
-                     current->ret_stack[index].fp,
-                     frame_pointer,
-                     (void *)current->ret_stack[index].func,
-                     current->ret_stack[index].ret);
-                *ret = (unsigned long)panic;
-                return;
-        }
-#endif
-
-        *ret = current->ret_stack[index].ret;
-        trace->func = current->ret_stack[index].func;
-        trace->calltime = current->ret_stack[index].calltime;
-        trace->overrun = atomic_read(&current->trace_overrun);
-        trace->depth = current->curr_ret_depth--;
-        /*
-         * We still want to trace interrupts coming in if
-         * max_depth is set to 1. Make sure the decrement is
-         * seen before ftrace_graph_return.
-         */
-        barrier();
-}
-
-/*
- * Send the trace to the ring-buffer.
- * @return the original return address.
- */
-unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
-{
-        struct ftrace_graph_ret trace;
-        unsigned long ret;
-
-        ftrace_pop_return_trace(&trace, &ret, frame_pointer);
-        trace.rettime = trace_clock_local();
-        ftrace_graph_return(&trace);
-        /*
-         * The ftrace_graph_return() may still access the current
-         * ret_stack structure, we need to make sure the update of
-         * curr_ret_stack is after that.
-         */
-        barrier();
-        current->curr_ret_stack--;
-        /*
-         * The curr_ret_stack can be less than -1 only if it was
-         * filtered out and it's about to return from the function.
-         * Recover the index and continue to trace normal functions.
-         */
-        if (current->curr_ret_stack < -1) {
-                current->curr_ret_stack += FTRACE_NOTRACE_DEPTH;
-                return ret;
-        }
-
-        if (unlikely(!ret)) {
-                ftrace_graph_stop();
-                WARN_ON(1);
-                /* Might as well panic. What else to do? */
-                ret = (unsigned long)panic;
-        }
-
-        return ret;
-}
-
 /**
  * ftrace_graph_ret_addr - convert a potentially modified stack return address
  *                         to its original value