![Steven Rostedt](/assets/img/avatar_default.png)
This patch adds the new function selection commands traceon and traceoff. traceon sets the function to enable the ring buffers while traceoff disables the ring buffers. You can pass in the number of times you want the command to be executed when the function is hit. It will only execute if the state of the buffers are not already in that state. Example: # echo do_fork:traceon:4 Will enable the ring buffers if they are disabled every time it hits do_fork, up to 4 times. # echo sys_close:traceoff This will disable the ring buffers every time (unlimited) when sys_close is called. Signed-off-by: Steven Rostedt <srostedt@redhat.com>
375 lines
7.5 KiB
C
375 lines
7.5 KiB
C
/*
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* ring buffer based function tracer
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*
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
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*
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* Based on code from 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/ring_buffer.h>
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#include <linux/debugfs.h>
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#include <linux/uaccess.h>
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#include <linux/ftrace.h>
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#include <linux/fs.h>
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#include "trace.h"
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/* function tracing enabled */
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static int ftrace_function_enabled;
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static struct trace_array *func_trace;
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static void tracing_start_function_trace(void);
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static void tracing_stop_function_trace(void);
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static int function_trace_init(struct trace_array *tr)
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{
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func_trace = tr;
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tr->cpu = get_cpu();
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put_cpu();
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tracing_start_cmdline_record();
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tracing_start_function_trace();
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return 0;
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}
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static void function_trace_reset(struct trace_array *tr)
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{
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tracing_stop_function_trace();
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tracing_stop_cmdline_record();
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}
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static void function_trace_start(struct trace_array *tr)
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{
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tracing_reset_online_cpus(tr);
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}
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static void
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function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip)
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{
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struct trace_array *tr = func_trace;
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struct trace_array_cpu *data;
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unsigned long flags;
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long disabled;
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int cpu, resched;
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int pc;
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if (unlikely(!ftrace_function_enabled))
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return;
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pc = preempt_count();
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resched = ftrace_preempt_disable();
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local_save_flags(flags);
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cpu = raw_smp_processor_id();
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data = tr->data[cpu];
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disabled = atomic_inc_return(&data->disabled);
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if (likely(disabled == 1))
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trace_function(tr, ip, parent_ip, flags, pc);
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atomic_dec(&data->disabled);
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ftrace_preempt_enable(resched);
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}
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static void
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function_trace_call(unsigned long ip, unsigned long parent_ip)
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{
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struct trace_array *tr = func_trace;
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struct trace_array_cpu *data;
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unsigned long flags;
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long disabled;
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int cpu;
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int pc;
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if (unlikely(!ftrace_function_enabled))
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return;
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/*
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* Need to use raw, since this must be called before the
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* recursive protection is performed.
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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 = tr->data[cpu];
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disabled = atomic_inc_return(&data->disabled);
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if (likely(disabled == 1)) {
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pc = preempt_count();
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trace_function(tr, ip, parent_ip, flags, pc);
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}
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atomic_dec(&data->disabled);
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local_irq_restore(flags);
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}
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static void
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function_stack_trace_call(unsigned long ip, unsigned long parent_ip)
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{
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struct trace_array *tr = func_trace;
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struct trace_array_cpu *data;
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unsigned long flags;
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long disabled;
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int cpu;
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int pc;
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if (unlikely(!ftrace_function_enabled))
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return;
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/*
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* Need to use raw, since this must be called before the
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* recursive protection is performed.
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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 = tr->data[cpu];
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disabled = atomic_inc_return(&data->disabled);
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if (likely(disabled == 1)) {
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pc = preempt_count();
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trace_function(tr, ip, parent_ip, flags, pc);
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/*
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* skip over 5 funcs:
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* __ftrace_trace_stack,
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* __trace_stack,
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* function_stack_trace_call
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* ftrace_list_func
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* ftrace_call
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*/
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__trace_stack(tr, flags, 5, pc);
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}
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atomic_dec(&data->disabled);
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local_irq_restore(flags);
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}
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static struct ftrace_ops trace_ops __read_mostly =
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{
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.func = function_trace_call,
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};
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static struct ftrace_ops trace_stack_ops __read_mostly =
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{
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.func = function_stack_trace_call,
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};
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/* Our two options */
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enum {
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TRACE_FUNC_OPT_STACK = 0x1,
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};
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static struct tracer_opt func_opts[] = {
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#ifdef CONFIG_STACKTRACE
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{ TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
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#endif
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{ } /* Always set a last empty entry */
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};
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static struct tracer_flags func_flags = {
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.val = 0, /* By default: all flags disabled */
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.opts = func_opts
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};
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static void tracing_start_function_trace(void)
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{
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ftrace_function_enabled = 0;
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if (trace_flags & TRACE_ITER_PREEMPTONLY)
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trace_ops.func = function_trace_call_preempt_only;
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else
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trace_ops.func = function_trace_call;
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if (func_flags.val & TRACE_FUNC_OPT_STACK)
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register_ftrace_function(&trace_stack_ops);
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else
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register_ftrace_function(&trace_ops);
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ftrace_function_enabled = 1;
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}
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static void tracing_stop_function_trace(void)
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{
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ftrace_function_enabled = 0;
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/* OK if they are not registered */
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unregister_ftrace_function(&trace_stack_ops);
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unregister_ftrace_function(&trace_ops);
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}
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static int func_set_flag(u32 old_flags, u32 bit, int set)
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{
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if (bit == TRACE_FUNC_OPT_STACK) {
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/* do nothing if already set */
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if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
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return 0;
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if (set) {
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unregister_ftrace_function(&trace_ops);
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register_ftrace_function(&trace_stack_ops);
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} else {
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unregister_ftrace_function(&trace_stack_ops);
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register_ftrace_function(&trace_ops);
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}
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return 0;
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}
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return -EINVAL;
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}
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static struct tracer function_trace __read_mostly =
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{
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.name = "function",
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.init = function_trace_init,
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.reset = function_trace_reset,
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.start = function_trace_start,
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.flags = &func_flags,
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.set_flag = func_set_flag,
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#ifdef CONFIG_FTRACE_SELFTEST
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.selftest = trace_selftest_startup_function,
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#endif
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};
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#ifdef CONFIG_DYNAMIC_FTRACE
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static void
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ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
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{
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long *count = (long *)data;
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if (tracing_is_on())
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return;
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if (!*count)
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return;
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if (*count != -1)
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(*count)--;
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tracing_on();
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}
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static void
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ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
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{
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long *count = (long *)data;
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if (!tracing_is_on())
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return;
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if (!*count)
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return;
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if (*count != -1)
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(*count)--;
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tracing_off();
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}
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static struct ftrace_hook_ops traceon_hook_ops = {
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.func = ftrace_traceon,
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};
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static struct ftrace_hook_ops traceoff_hook_ops = {
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.func = ftrace_traceoff,
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};
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static int
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ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)
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{
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struct ftrace_hook_ops *ops;
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/* we register both traceon and traceoff to this callback */
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if (strcmp(cmd, "traceon") == 0)
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ops = &traceon_hook_ops;
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else
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ops = &traceoff_hook_ops;
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unregister_ftrace_function_hook_func(glob, ops);
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return 0;
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}
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static int
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ftrace_trace_onoff_callback(char *glob, char *cmd, char *param, int enable)
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{
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struct ftrace_hook_ops *ops;
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void *count = (void *)-1;
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char *number;
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int ret;
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/* hash funcs only work with set_ftrace_filter */
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if (!enable)
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return -EINVAL;
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if (glob[0] == '!')
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return ftrace_trace_onoff_unreg(glob+1, cmd, param);
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/* we register both traceon and traceoff to this callback */
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if (strcmp(cmd, "traceon") == 0)
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ops = &traceon_hook_ops;
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else
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ops = &traceoff_hook_ops;
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if (!param)
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goto out_reg;
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number = strsep(¶m, ":");
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if (!strlen(number))
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goto out_reg;
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/*
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* We use the callback data field (which is a pointer)
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* as our counter.
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*/
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ret = strict_strtoul(number, 0, (unsigned long *)&count);
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if (ret)
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return ret;
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out_reg:
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ret = register_ftrace_function_hook(glob, ops, count);
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return ret;
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}
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static struct ftrace_func_command ftrace_traceon_cmd = {
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.name = "traceon",
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.func = ftrace_trace_onoff_callback,
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};
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static struct ftrace_func_command ftrace_traceoff_cmd = {
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.name = "traceoff",
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.func = ftrace_trace_onoff_callback,
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};
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static int __init init_func_cmd_traceon(void)
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{
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int ret;
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ret = register_ftrace_command(&ftrace_traceoff_cmd);
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if (ret)
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return ret;
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ret = register_ftrace_command(&ftrace_traceon_cmd);
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if (ret)
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unregister_ftrace_command(&ftrace_traceoff_cmd);
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return ret;
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}
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#else
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static inline int init_func_cmd_traceon(void)
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{
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return 0;
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}
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#endif /* CONFIG_DYNAMIC_FTRACE */
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static __init int init_function_trace(void)
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{
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init_func_cmd_traceon();
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return register_tracer(&function_trace);
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}
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device_initcall(init_function_trace);
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