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fgraph: Have set_graph_notrace only affect function_graph tracer
In order to make the function graph infrastructure more generic, there can not be code specific for the function_graph tracer in the generic code. This includes the set_graph_notrace logic, that stops all graph calls when a function in the set_graph_notrace is hit. By using the trace_recursion mask, we can use a bit in the current task_struct to implement the notrace code, and move the logic out of fgraph.c and into trace_functions_graph.c and keeps it affecting only the tracer and not all call graph callbacks. Acked-by: Namhyung Kim <namhyung@kernel.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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d864a3ca88
commit
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3 changed files with 29 additions and 21 deletions
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@ -64,30 +64,9 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
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return -EBUSY;
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}
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/*
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* The curr_ret_stack is an index to ftrace return stack of
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* current task. Its value should be in [0, FTRACE_RETFUNC_
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* DEPTH) when the function graph tracer is used. To support
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* filtering out specific functions, it makes the index
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* negative by subtracting huge value (FTRACE_NOTRACE_DEPTH)
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* so when it sees a negative index the ftrace will ignore
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* the record. And the index gets recovered when returning
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* from the filtered function by adding the FTRACE_NOTRACE_
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* DEPTH and then it'll continue to record functions normally.
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*
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* The curr_ret_stack is initialized to -1 and get increased
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* in this function. So it can be less than -1 only if it was
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* filtered out via ftrace_graph_notrace_addr() which can be
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* set from set_graph_notrace file in tracefs by user.
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*/
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if (current->curr_ret_stack < -1)
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return -EBUSY;
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calltime = trace_clock_local();
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index = ++current->curr_ret_stack;
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if (ftrace_graph_notrace_addr(func))
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current->curr_ret_stack -= FTRACE_NOTRACE_DEPTH;
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barrier();
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current->ret_stack[index].ret = ret;
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current->ret_stack[index].func = func;
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@ -534,6 +534,13 @@ enum {
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TRACE_GRAPH_DEPTH_START_BIT,
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TRACE_GRAPH_DEPTH_END_BIT,
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/*
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* To implement set_graph_notrace, if this bit is set, we ignore
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* function graph tracing of called functions, until the return
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* function is called to clear it.
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*/
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TRACE_GRAPH_NOTRACE_BIT,
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};
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#define trace_recursion_set(bit) do { (current)->trace_recursion |= (1<<(bit)); } while (0)
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@ -188,6 +188,18 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
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int cpu;
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int pc;
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if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT))
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return 0;
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if (ftrace_graph_notrace_addr(trace->func)) {
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trace_recursion_set(TRACE_GRAPH_NOTRACE_BIT);
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/*
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* Need to return 1 to have the return called
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* that will clear the NOTRACE bit.
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*/
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return 1;
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}
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if (!ftrace_trace_task(tr))
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return 0;
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@ -290,6 +302,11 @@ void trace_graph_return(struct ftrace_graph_ret *trace)
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ftrace_graph_addr_finish(trace);
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if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {
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trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);
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return;
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}
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local_irq_save(flags);
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cpu = raw_smp_processor_id();
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data = per_cpu_ptr(tr->trace_buffer.data, cpu);
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@ -315,6 +332,11 @@ static void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
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{
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ftrace_graph_addr_finish(trace);
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if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {
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trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);
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return;
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}
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if (tracing_thresh &&
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(trace->rettime - trace->calltime < tracing_thresh))
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return;
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