139 lines
3.4 KiB
C
139 lines
3.4 KiB
C
/*
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* Infrastructure for profiling code inserted by 'gcc -pg'.
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*
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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* Copyright (C) 2004-2008 Ingo Molnar <mingo@redhat.com>
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*
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* Originally ported from the -rt patch by:
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* Copyright (C) 2007 Arnaldo Carvalho de Melo <acme@redhat.com>
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*
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* Based on code in the latency_tracer, that is:
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*
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* Copyright (C) 2004-2006 Ingo Molnar
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* Copyright (C) 2004 William Lee Irwin III
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*/
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#include <linux/module.h>
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#include <linux/ftrace.h>
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static DEFINE_SPINLOCK(ftrace_func_lock);
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static struct ftrace_ops ftrace_list_end __read_mostly =
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{
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.func = ftrace_stub,
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};
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static struct ftrace_ops *ftrace_list __read_mostly = &ftrace_list_end;
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ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
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/* mcount is defined per arch in assembly */
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EXPORT_SYMBOL(mcount);
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notrace void ftrace_list_func(unsigned long ip, unsigned long parent_ip)
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{
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struct ftrace_ops *op = ftrace_list;
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/* in case someone actually ports this to alpha! */
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read_barrier_depends();
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while (op != &ftrace_list_end) {
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/* silly alpha */
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read_barrier_depends();
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op->func(ip, parent_ip);
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op = op->next;
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};
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}
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/**
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* register_ftrace_function - register a function for profiling
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* @ops - ops structure that holds the function for profiling.
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*
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* Register a function to be called by all functions in the
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* kernel.
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*
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* Note: @ops->func and all the functions it calls must be labeled
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* with "notrace", otherwise it will go into a
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* recursive loop.
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*/
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int register_ftrace_function(struct ftrace_ops *ops)
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{
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unsigned long flags;
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spin_lock_irqsave(&ftrace_func_lock, flags);
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ops->next = ftrace_list;
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/*
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* We are entering ops into the ftrace_list but another
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* CPU might be walking that list. We need to make sure
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* the ops->next pointer is valid before another CPU sees
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* the ops pointer included into the ftrace_list.
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*/
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smp_wmb();
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ftrace_list = ops;
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/*
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* For one func, simply call it directly.
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* For more than one func, call the chain.
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*/
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if (ops->next == &ftrace_list_end)
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ftrace_trace_function = ops->func;
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else
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ftrace_trace_function = ftrace_list_func;
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spin_unlock_irqrestore(&ftrace_func_lock, flags);
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return 0;
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}
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/**
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* unregister_ftrace_function - unresgister a function for profiling.
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* @ops - ops structure that holds the function to unregister
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*
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* Unregister a function that was added to be called by ftrace profiling.
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*/
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int unregister_ftrace_function(struct ftrace_ops *ops)
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{
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unsigned long flags;
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struct ftrace_ops **p;
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int ret = 0;
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spin_lock_irqsave(&ftrace_func_lock, flags);
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/*
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* If we are the only function, then the ftrace pointer is
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* pointing directly to that function.
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*/
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if (ftrace_list == ops && ops->next == &ftrace_list_end) {
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ftrace_trace_function = ftrace_stub;
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ftrace_list = &ftrace_list_end;
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goto out;
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}
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for (p = &ftrace_list; *p != &ftrace_list_end; p = &(*p)->next)
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if (*p == ops)
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break;
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if (*p != ops) {
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ret = -1;
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goto out;
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}
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*p = (*p)->next;
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/* If we only have one func left, then call that directly */
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if (ftrace_list->next == &ftrace_list_end)
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ftrace_trace_function = ftrace_list->func;
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out:
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spin_unlock_irqrestore(&ftrace_func_lock, flags);
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return 0;
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}
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/**
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* clear_ftrace_function - reset the ftrace function
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*
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* This NULLs the ftrace function and in essence stops
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* tracing. There may be lag
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*/
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void clear_ftrace_function(void)
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{
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ftrace_trace_function = ftrace_stub;
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}
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