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695 lines
15 KiB
695 lines
15 KiB
/* |
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* ring buffer based function tracer |
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* |
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* Copyright (C) 2007-2008 Steven Rostedt <[email protected]> |
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* Copyright (C) 2008 Ingo Molnar <[email protected]> |
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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 Nadia Yvette Chambers |
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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/slab.h> |
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#include <linux/fs.h> |
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|
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#include "trace.h" |
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|
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static void tracing_start_function_trace(struct trace_array *tr); |
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static void tracing_stop_function_trace(struct trace_array *tr); |
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static void |
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function_trace_call(unsigned long ip, unsigned long parent_ip, |
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struct ftrace_ops *op, struct pt_regs *pt_regs); |
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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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struct ftrace_ops *op, struct pt_regs *pt_regs); |
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static struct tracer_flags func_flags; |
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|
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/* Our option */ |
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enum { |
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TRACE_FUNC_OPT_STACK = 0x1, |
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}; |
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static int allocate_ftrace_ops(struct trace_array *tr) |
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{ |
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struct ftrace_ops *ops; |
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ops = kzalloc(sizeof(*ops), GFP_KERNEL); |
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if (!ops) |
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return -ENOMEM; |
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/* Currently only the non stack verision is supported */ |
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ops->func = function_trace_call; |
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ops->flags = FTRACE_OPS_FL_RECURSION_SAFE | FTRACE_OPS_FL_PID; |
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tr->ops = ops; |
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ops->private = tr; |
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return 0; |
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} |
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int ftrace_create_function_files(struct trace_array *tr, |
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struct dentry *parent) |
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{ |
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int ret; |
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/* |
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* The top level array uses the "global_ops", and the files are |
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* created on boot up. |
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*/ |
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if (tr->flags & TRACE_ARRAY_FL_GLOBAL) |
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return 0; |
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ret = allocate_ftrace_ops(tr); |
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if (ret) |
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return ret; |
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ftrace_create_filter_files(tr->ops, parent); |
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|
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return 0; |
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} |
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void ftrace_destroy_function_files(struct trace_array *tr) |
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{ |
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ftrace_destroy_filter_files(tr->ops); |
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kfree(tr->ops); |
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tr->ops = NULL; |
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} |
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static int function_trace_init(struct trace_array *tr) |
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{ |
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ftrace_func_t func; |
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|
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/* |
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* Instance trace_arrays get their ops allocated |
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* at instance creation. Unless it failed |
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* the allocation. |
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*/ |
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if (!tr->ops) |
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return -ENOMEM; |
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/* Currently only the global instance can do stack tracing */ |
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if (tr->flags & TRACE_ARRAY_FL_GLOBAL && |
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func_flags.val & TRACE_FUNC_OPT_STACK) |
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func = function_stack_trace_call; |
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else |
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func = function_trace_call; |
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ftrace_init_array_ops(tr, func); |
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tr->trace_buffer.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(tr); |
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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(tr); |
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tracing_stop_cmdline_record(); |
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ftrace_reset_array_ops(tr); |
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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->trace_buffer); |
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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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struct ftrace_ops *op, struct pt_regs *pt_regs) |
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{ |
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struct trace_array *tr = op->private; |
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struct trace_array_cpu *data; |
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unsigned long flags; |
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int bit; |
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int cpu; |
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int pc; |
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if (unlikely(!tr->function_enabled)) |
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return; |
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pc = preempt_count(); |
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preempt_disable_notrace(); |
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bit = trace_test_and_set_recursion(TRACE_FTRACE_START, TRACE_FTRACE_MAX); |
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if (bit < 0) |
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goto out; |
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cpu = smp_processor_id(); |
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data = per_cpu_ptr(tr->trace_buffer.data, cpu); |
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if (!atomic_read(&data->disabled)) { |
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local_save_flags(flags); |
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trace_function(tr, ip, parent_ip, flags, pc); |
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} |
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trace_clear_recursion(bit); |
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out: |
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preempt_enable_notrace(); |
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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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struct ftrace_ops *op, struct pt_regs *pt_regs) |
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{ |
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struct trace_array *tr = op->private; |
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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(!tr->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 = per_cpu_ptr(tr->trace_buffer.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 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(struct trace_array *tr) |
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{ |
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tr->function_enabled = 0; |
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register_ftrace_function(tr->ops); |
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tr->function_enabled = 1; |
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} |
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static void tracing_stop_function_trace(struct trace_array *tr) |
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{ |
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tr->function_enabled = 0; |
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unregister_ftrace_function(tr->ops); |
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} |
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static struct tracer function_trace; |
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static int |
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func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set) |
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{ |
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switch (bit) { |
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case 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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break; |
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/* We can change this flag when not running. */ |
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if (tr->current_trace != &function_trace) |
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break; |
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unregister_ftrace_function(tr->ops); |
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if (set) { |
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tr->ops->func = function_stack_trace_call; |
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register_ftrace_function(tr->ops); |
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} else { |
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tr->ops->func = function_trace_call; |
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register_ftrace_function(tr->ops); |
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} |
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break; |
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default: |
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return -EINVAL; |
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} |
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return 0; |
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} |
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static struct tracer function_trace __tracer_data = |
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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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.allow_instances = true, |
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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 update_traceon_count(void **data, bool on) |
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{ |
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long *count = (long *)data; |
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long old_count = *count; |
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/* |
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* Tracing gets disabled (or enabled) once per count. |
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* This function can be called at the same time on multiple CPUs. |
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* It is fine if both disable (or enable) tracing, as disabling |
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* (or enabling) the second time doesn't do anything as the |
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* state of the tracer is already disabled (or enabled). |
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* What needs to be synchronized in this case is that the count |
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* only gets decremented once, even if the tracer is disabled |
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* (or enabled) twice, as the second one is really a nop. |
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* |
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* The memory barriers guarantee that we only decrement the |
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* counter once. First the count is read to a local variable |
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* and a read barrier is used to make sure that it is loaded |
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* before checking if the tracer is in the state we want. |
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* If the tracer is not in the state we want, then the count |
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* is guaranteed to be the old count. |
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* |
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* Next the tracer is set to the state we want (disabled or enabled) |
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* then a write memory barrier is used to make sure that |
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* the new state is visible before changing the counter by |
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* one minus the old counter. This guarantees that another CPU |
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* executing this code will see the new state before seeing |
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* the new counter value, and would not do anything if the new |
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* counter is seen. |
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* |
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* Note, there is no synchronization between this and a user |
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* setting the tracing_on file. But we currently don't care |
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* about that. |
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*/ |
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if (!old_count) |
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return; |
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/* Make sure we see count before checking tracing state */ |
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smp_rmb(); |
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if (on == !!tracing_is_on()) |
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return; |
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if (on) |
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tracing_on(); |
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else |
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tracing_off(); |
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/* unlimited? */ |
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if (old_count == -1) |
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return; |
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/* Make sure tracing state is visible before updating count */ |
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smp_wmb(); |
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*count = old_count - 1; |
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} |
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static void |
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ftrace_traceon_count(unsigned long ip, unsigned long parent_ip, void **data) |
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{ |
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update_traceon_count(data, 1); |
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} |
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static void |
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ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip, void **data) |
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{ |
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update_traceon_count(data, 0); |
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} |
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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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if (tracing_is_on()) |
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return; |
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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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if (!tracing_is_on()) |
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return; |
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tracing_off(); |
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} |
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/* |
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* Skip 4: |
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* ftrace_stacktrace() |
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* function_trace_probe_call() |
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* ftrace_ops_list_func() |
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* ftrace_call() |
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*/ |
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#define STACK_SKIP 4 |
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static void |
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ftrace_stacktrace(unsigned long ip, unsigned long parent_ip, void **data) |
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{ |
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trace_dump_stack(STACK_SKIP); |
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} |
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static void |
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ftrace_stacktrace_count(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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long old_count; |
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long new_count; |
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|
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/* |
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* Stack traces should only execute the number of times the |
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* user specified in the counter. |
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*/ |
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do { |
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|
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if (!tracing_is_on()) |
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return; |
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old_count = *count; |
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if (!old_count) |
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return; |
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/* unlimited? */ |
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if (old_count == -1) { |
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trace_dump_stack(STACK_SKIP); |
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return; |
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} |
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new_count = old_count - 1; |
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new_count = cmpxchg(count, old_count, new_count); |
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if (new_count == old_count) |
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trace_dump_stack(STACK_SKIP); |
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|
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} while (new_count != old_count); |
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} |
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|
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static int update_count(void **data) |
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{ |
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unsigned long *count = (long *)data; |
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|
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if (!*count) |
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return 0; |
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|
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if (*count != -1) |
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(*count)--; |
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return 1; |
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} |
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static void |
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ftrace_dump_probe(unsigned long ip, unsigned long parent_ip, void **data) |
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{ |
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if (update_count(data)) |
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ftrace_dump(DUMP_ALL); |
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} |
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|
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/* Only dump the current CPU buffer. */ |
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static void |
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ftrace_cpudump_probe(unsigned long ip, unsigned long parent_ip, void **data) |
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{ |
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if (update_count(data)) |
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ftrace_dump(DUMP_ORIG); |
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} |
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static int |
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ftrace_probe_print(const char *name, struct seq_file *m, |
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unsigned long ip, void *data) |
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{ |
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long count = (long)data; |
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seq_printf(m, "%ps:%s", (void *)ip, name); |
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|
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if (count == -1) |
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seq_puts(m, ":unlimited\n"); |
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else |
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seq_printf(m, ":count=%ld\n", count); |
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return 0; |
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} |
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static int |
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ftrace_traceon_print(struct seq_file *m, unsigned long ip, |
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struct ftrace_probe_ops *ops, void *data) |
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{ |
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return ftrace_probe_print("traceon", m, ip, data); |
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} |
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static int |
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ftrace_traceoff_print(struct seq_file *m, unsigned long ip, |
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struct ftrace_probe_ops *ops, void *data) |
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{ |
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return ftrace_probe_print("traceoff", m, ip, data); |
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} |
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static int |
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ftrace_stacktrace_print(struct seq_file *m, unsigned long ip, |
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struct ftrace_probe_ops *ops, void *data) |
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{ |
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return ftrace_probe_print("stacktrace", m, ip, data); |
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} |
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static int |
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ftrace_dump_print(struct seq_file *m, unsigned long ip, |
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struct ftrace_probe_ops *ops, void *data) |
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{ |
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return ftrace_probe_print("dump", m, ip, data); |
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} |
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static int |
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ftrace_cpudump_print(struct seq_file *m, unsigned long ip, |
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struct ftrace_probe_ops *ops, void *data) |
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{ |
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return ftrace_probe_print("cpudump", m, ip, data); |
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} |
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static struct ftrace_probe_ops traceon_count_probe_ops = { |
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.func = ftrace_traceon_count, |
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.print = ftrace_traceon_print, |
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}; |
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static struct ftrace_probe_ops traceoff_count_probe_ops = { |
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.func = ftrace_traceoff_count, |
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.print = ftrace_traceoff_print, |
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}; |
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static struct ftrace_probe_ops stacktrace_count_probe_ops = { |
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.func = ftrace_stacktrace_count, |
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.print = ftrace_stacktrace_print, |
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}; |
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static struct ftrace_probe_ops dump_probe_ops = { |
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.func = ftrace_dump_probe, |
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.print = ftrace_dump_print, |
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}; |
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static struct ftrace_probe_ops cpudump_probe_ops = { |
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.func = ftrace_cpudump_probe, |
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.print = ftrace_cpudump_print, |
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}; |
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static struct ftrace_probe_ops traceon_probe_ops = { |
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.func = ftrace_traceon, |
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.print = ftrace_traceon_print, |
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}; |
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static struct ftrace_probe_ops traceoff_probe_ops = { |
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.func = ftrace_traceoff, |
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.print = ftrace_traceoff_print, |
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}; |
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|
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static struct ftrace_probe_ops stacktrace_probe_ops = { |
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.func = ftrace_stacktrace, |
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.print = ftrace_stacktrace_print, |
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}; |
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|
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static int |
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ftrace_trace_probe_callback(struct ftrace_probe_ops *ops, |
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struct ftrace_hash *hash, char *glob, |
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char *cmd, char *param, int enable) |
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{ |
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void *count = (void *)-1; |
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char *number; |
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int ret; |
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|
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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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|
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if (glob[0] == '!') { |
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unregister_ftrace_function_probe_func(glob+1, ops); |
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return 0; |
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} |
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|
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if (!param) |
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goto out_reg; |
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|
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number = strsep(¶m, ":"); |
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|
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if (!strlen(number)) |
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goto out_reg; |
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|
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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 = kstrtoul(number, 0, (unsigned long *)&count); |
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if (ret) |
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return ret; |
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|
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out_reg: |
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ret = register_ftrace_function_probe(glob, ops, count); |
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|
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return ret < 0 ? ret : 0; |
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} |
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|
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static int |
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ftrace_trace_onoff_callback(struct ftrace_hash *hash, |
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char *glob, char *cmd, char *param, int enable) |
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{ |
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struct ftrace_probe_ops *ops; |
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|
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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 = param ? &traceon_count_probe_ops : &traceon_probe_ops; |
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else |
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ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops; |
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|
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return ftrace_trace_probe_callback(ops, hash, glob, cmd, |
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param, enable); |
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} |
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|
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static int |
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ftrace_stacktrace_callback(struct ftrace_hash *hash, |
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char *glob, char *cmd, char *param, int enable) |
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{ |
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struct ftrace_probe_ops *ops; |
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|
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ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops; |
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|
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return ftrace_trace_probe_callback(ops, hash, glob, cmd, |
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param, enable); |
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} |
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|
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static int |
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ftrace_dump_callback(struct ftrace_hash *hash, |
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char *glob, char *cmd, char *param, int enable) |
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{ |
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struct ftrace_probe_ops *ops; |
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|
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ops = &dump_probe_ops; |
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|
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/* Only dump once. */ |
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return ftrace_trace_probe_callback(ops, hash, glob, cmd, |
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"1", enable); |
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} |
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|
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static int |
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ftrace_cpudump_callback(struct ftrace_hash *hash, |
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char *glob, char *cmd, char *param, int enable) |
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{ |
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struct ftrace_probe_ops *ops; |
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|
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ops = &cpudump_probe_ops; |
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|
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/* Only dump once. */ |
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return ftrace_trace_probe_callback(ops, hash, glob, cmd, |
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"1", enable); |
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} |
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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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|
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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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|
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static struct ftrace_func_command ftrace_stacktrace_cmd = { |
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.name = "stacktrace", |
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.func = ftrace_stacktrace_callback, |
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}; |
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|
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static struct ftrace_func_command ftrace_dump_cmd = { |
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.name = "dump", |
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.func = ftrace_dump_callback, |
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}; |
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|
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static struct ftrace_func_command ftrace_cpudump_cmd = { |
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.name = "cpudump", |
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.func = ftrace_cpudump_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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|
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ret = register_ftrace_command(&ftrace_traceoff_cmd); |
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if (ret) |
|
return ret; |
|
|
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ret = register_ftrace_command(&ftrace_traceon_cmd); |
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if (ret) |
|
goto out_free_traceoff; |
|
|
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ret = register_ftrace_command(&ftrace_stacktrace_cmd); |
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if (ret) |
|
goto out_free_traceon; |
|
|
|
ret = register_ftrace_command(&ftrace_dump_cmd); |
|
if (ret) |
|
goto out_free_stacktrace; |
|
|
|
ret = register_ftrace_command(&ftrace_cpudump_cmd); |
|
if (ret) |
|
goto out_free_dump; |
|
|
|
return 0; |
|
|
|
out_free_dump: |
|
unregister_ftrace_command(&ftrace_dump_cmd); |
|
out_free_stacktrace: |
|
unregister_ftrace_command(&ftrace_stacktrace_cmd); |
|
out_free_traceon: |
|
unregister_ftrace_command(&ftrace_traceon_cmd); |
|
out_free_traceoff: |
|
unregister_ftrace_command(&ftrace_traceoff_cmd); |
|
|
|
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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{ |
|
return 0; |
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} |
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#endif /* CONFIG_DYNAMIC_FTRACE */ |
|
|
|
static __init int init_function_trace(void) |
|
{ |
|
init_func_cmd_traceon(); |
|
return register_tracer(&function_trace); |
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} |
|
core_initcall(init_function_trace);
|
|
|