Release 4.15 kernel/trace/trace_functions_graph.c

Directory: kernel/trace
// SPDX-License-Identifier: GPL-2.0
/*
 *
 * Function graph tracer.
 * Copyright (c) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com>
 * Mostly borrowed from function tracer which
 * is Copyright (c) Steven Rostedt <srostedt@redhat.com>
 *
 */
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/fs.h>

#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;
}

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Steven Rostedt 10 100.00% 1 100.00%
Total 10 100.00% 1 100.00%

/**
 * 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;
}

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Total 11 100.00% 1 100.00%

/* When set, irq functions will be ignored */

static int ftrace_graph_skip_irqs;


struct fgraph_cpu_data {
	
pid_t		last_pid;
	
int		depth;
	
int		depth_irq;
	
int		ignore;
	
unsigned long	enter_funcs[FTRACE_RETFUNC_DEPTH];
};


struct fgraph_data {
	
struct fgraph_cpu_data __percpu *cpu_data;

	/* Place to preserve last processed entry. */
	
struct ftrace_graph_ent_entry	ent;
	
struct ftrace_graph_ret_entry	ret;
	
int				failed;
	
int				cpu;
};


#define TRACE_GRAPH_INDENT	2


unsigned int fgraph_max_depth;


static struct tracer_opt trace_opts[] = {
	/* Display overruns? (for self-debug purpose) */
	{ TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
	/* Display CPU ? */
	{ TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
	/* Display Overhead ? */
	{ TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
	/* Display proc name/pid */
	{ TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) },
	/* Display duration of execution */
	{ TRACER_OPT(funcgraph-duration, TRACE_GRAPH_PRINT_DURATION) },
	/* Display absolute time of an entry */
	{ TRACER_OPT(funcgraph-abstime, TRACE_GRAPH_PRINT_ABS_TIME) },
	/* Display interrupts */
	{ TRACER_OPT(funcgraph-irqs, TRACE_GRAPH_PRINT_IRQS) },
	/* Display function name after trailing } */
	{ TRACER_OPT(funcgraph-tail, TRACE_GRAPH_PRINT_TAIL) },
	/* Include sleep time (scheduled out) between entry and return */
	{ TRACER_OPT(sleep-time, TRACE_GRAPH_SLEEP_TIME) },
	/* Include time within nested functions */
	{ TRACER_OPT(graph-time, TRACE_GRAPH_GRAPH_TIME) },
	{ } /* Empty entry */
};


static struct tracer_flags tracer_flags = {
	/* Don't display overruns, proc, or tail by default */
	.val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD |
	       TRACE_GRAPH_PRINT_DURATION | TRACE_GRAPH_PRINT_IRQS |
	       TRACE_GRAPH_SLEEP_TIME | TRACE_GRAPH_GRAPH_TIME,
	.opts = trace_opts
};


static struct trace_array *graph_array;

/*
 * DURATION column is being also used to display IRQ signs,
 * following values are used by print_graph_irq and others
 * to fill in space into DURATION column.
 */
enum {
	
FLAGS_FILL_FULL  = 1 << TRACE_GRAPH_PRINT_FILL_SHIFT,
	
FLAGS_FILL_START = 2 << TRACE_GRAPH_PRINT_FILL_SHIFT,
	
FLAGS_FILL_END   = 3 << TRACE_GRAPH_PRINT_FILL_SHIFT,
};

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.*/

int

ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
			 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
	*depth = current->curr_ret_stack;

	return 0;
}

Contributors
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Steven Rostedt 148 72.91% 6 66.67%
Namhyung Kim 29 14.29% 1 11.11%
Josh Poimboeuf 26 12.81% 2 22.22%
Total 203 100.00% 9 100.00%

/* 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 = index;
}

Contributors
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Steven Rostedt 190 91.35% 5 71.43%
Namhyung Kim 15 7.21% 1 14.29%
Josh Poimboeuf 3 1.44% 1 14.29%
Total 208 100.00% 7 100.00%

/*
 * 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();
	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;
	}

	/*
         * The trace should run after decrementing the ret counter
         * in case an interrupt were to come in. We don't want to
         * lose the interrupt if max_depth is set.
         */
	ftrace_graph_return(&trace);

	if (unlikely(!ret)) {
		ftrace_graph_stop();
		WARN_ON(1);
		/* Might as well panic. What else to do? */
		ret = (unsigned long)panic;
	}

	return ret;
}

Contributors
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Steven Rostedt 80 78.43% 4 66.67%
Namhyung Kim 21 20.59% 1 16.67%
Frédéric Weisbecker 1 0.98% 1 16.67%
Total 102 100.00% 6 100.00%

/**
 * ftrace_graph_ret_addr - convert a potentially modified stack return address
 *                         to its original value
 *
 * This function can be called by stack unwinding code to convert a found stack
 * return address ('ret') to its original value, in case the function graph
 * tracer has modified it to be 'return_to_handler'.  If the address hasn't
 * been modified, the unchanged value of 'ret' is returned.
 *
 * 'idx' is a state variable which should be initialized by the caller to zero
 * before the first call.
 *
 * 'retp' is a pointer to the return address on the stack.  It's ignored if
 * the arch doesn't have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR defined.
 */
#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR


unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
				    unsigned long ret, unsigned long *retp)
{
	int index = task->curr_ret_stack;
	int i;

	if (ret != (unsigned long)return_to_handler)
		return ret;

	if (index < -1)
		index += FTRACE_NOTRACE_DEPTH;

	if (index < 0)
		return ret;

	for (i = 0; i <= index; i++)
		if (task->ret_stack[i].retp == retp)
			return task->ret_stack[i].ret;

	return ret;
}
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Total 106 100.00% 1 100.00%

#else /* !HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */


unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
				    unsigned long ret, unsigned long *retp)
{
	int task_idx;

	if (ret != (unsigned long)return_to_handler)
		return ret;

	task_idx = task->curr_ret_stack;

	if (!task->ret_stack || task_idx < *idx)
		return ret;

	task_idx -= *idx;
	(*idx)++;

	return task->ret_stack[task_idx].ret;
}
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Total 82 100.00% 1 100.00%

#endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */



int __trace_graph_entry(struct trace_array *tr,
				struct ftrace_graph_ent *trace,
				unsigned long flags,
				int pc)
{
	struct trace_event_call *call = &event_funcgraph_entry;
	struct ring_buffer_event *event;
	struct ring_buffer *buffer = tr->trace_buffer.buffer;
	struct ftrace_graph_ent_entry *entry;

	event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_ENT,
					  sizeof(*entry), flags, pc);
	if (!event)
		return 0;
	entry	= ring_buffer_event_data(event);
	entry->graph_ent			= *trace;
	if (!call_filter_check_discard(call, entry, buffer, event))
		trace_buffer_unlock_commit_nostack(buffer, event);

	return 1;
}

Contributors
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Frédéric Weisbecker 99 85.34% 1 16.67%
Steven Rostedt 14 12.07% 4 66.67%
Tom Zanussi 3 2.59% 1 16.67%
Total 116 100.00% 6 100.00%



static inline int ftrace_graph_ignore_irqs(void)
{
	if (!ftrace_graph_skip_irqs || trace_recursion_test(TRACE_IRQ_BIT))
		return 0;

	return in_irq();
}

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Steven Rostedt 26 100.00% 2 100.00%
Total 26 100.00% 2 100.00%



int trace_graph_entry(struct ftrace_graph_ent *trace)
{
	struct trace_array *tr = graph_array;
	struct trace_array_cpu *data;
	unsigned long flags;
	long disabled;
	int ret;
	int cpu;
	int pc;

	if (!ftrace_trace_task(tr))
		return 0;

	if (ftrace_graph_ignore_func(trace))
		return 0;

	if (ftrace_graph_ignore_irqs())
		return 0;

	/*
         * Do not trace a function if it's filtered by set_graph_notrace.
         * Make the index of ret stack negative to indicate that it should
         * ignore further functions.  But it needs its own ret stack entry
         * to recover the original index in order to continue tracing after
         * returning from the function.
         */
	if (ftrace_graph_notrace_addr(trace->func))
		return 1;

	/*
         * Stop here if tracing_threshold is set. We only write function return
         * events to the ring buffer.
         */
	if (tracing_thresh)
		return 1;

	local_irq_save(flags);
	cpu = raw_smp_processor_id();
	data = per_cpu_ptr(tr->trace_buffer.data, cpu);
	disabled = atomic_inc_return(&data->disabled);
	if (likely(disabled == 1)) {
		pc = preempt_count();
		ret = __trace_graph_entry(tr, trace, flags, pc);
	} else {
		ret = 0;
	}

	atomic_dec(&data->disabled);
	local_irq_restore(flags);

	return ret;
}

Contributors
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Frédéric Weisbecker 136 78.61% 1 12.50%
Steven Rostedt 16 9.25% 5 62.50%
Namhyung Kim 13 7.51% 1 12.50%
Joel A Fernandes 8 4.62% 1 12.50%
Total 173 100.00% 8 100.00%


static void

__trace_graph_function(struct trace_array *tr,
		unsigned long ip, unsigned long flags, int pc)
{
	u64 time = trace_clock_local();
	struct ftrace_graph_ent ent = {
		.func  = ip,
		.depth = 0,
        };
	struct ftrace_graph_ret ret = {
		.func     = ip,
		.depth    = 0,
		.calltime = time,
		.rettime  = time,
        };

	__trace_graph_entry(tr, &ent, flags, pc);
	__trace_graph_return(tr, &ret, flags, pc);
}

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Jiri Olsa 94 100.00% 1 100.00%
Total 94 100.00% 1 100.00%


void

trace_graph_function(struct trace_array *tr,
		unsigned long ip, unsigned long parent_ip,
		unsigned long flags, int pc)
{
	__trace_graph_function(tr, ip, flags, pc);
}

Contributors
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Jiri Olsa 36 100.00% 1 100.00%
Total 36 100.00% 1 100.00%



void __trace_graph_return(struct trace_array *tr,
				struct ftrace_graph_ret *trace,
				unsigned long flags,
				int pc)
{
	struct trace_event_call *call = &event_funcgraph_exit;
	struct ring_buffer_event *event;
	struct ring_buffer *buffer = tr->trace_buffer.buffer;
	struct ftrace_graph_ret_entry *entry;

	event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_RET,
					  sizeof(*entry), flags, pc);
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
	entry->ret				= *trace;
	if (!call_filter_check_discard(call, entry, buffer, event))
		trace_buffer_unlock_commit_nostack(buffer, event);
}

Contributors
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Frédéric Weisbecker 94 84.68% 1 16.67%
Steven Rostedt 14 12.61% 4 66.67%
Tom Zanussi 3 2.70% 1 16.67%
Total 111 100.00% 6 100.00%



void trace_graph_return(struct ftrace_graph_ret *trace)
{
	struct trace_array *tr = graph_array;
	struct trace_array_cpu *data;
	unsigned long flags;
	long disabled;
	int cpu;
	int pc;

	local_irq_save(flags);
	cpu = raw_smp_processor_id();
	data = per_cpu_ptr(tr->trace_buffer.data, cpu);
	disabled = atomic_inc_return(&data->disabled);
	if (likely(disabled == 1)) {
		pc = preempt_count();
		__trace_graph_return(tr, trace, flags, pc);
	}
	atomic_dec(&data->disabled);
	local_irq_restore(flags);
}

Contributors
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Frédéric Weisbecker 102 94.44% 1 33.33%
Steven Rostedt 6 5.56% 2 66.67%
Total 108 100.00% 3 100.00%



void set_graph_array(struct trace_array *tr)
{
	graph_array = tr;

	/* Make graph_array visible before we start tracing */

	smp_mb();
}

Contributors
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Frédéric Weisbecker 18 100.00% 1 100.00%
Total 18 100.00% 1 100.00%



static void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
{
	if (tracing_thresh &&
	    (trace->rettime - trace->calltime < tracing_thresh))
		return;
	else
		trace_graph_return(trace);
}

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Tim Bird 33 97.06% 1 50.00%
Steven Rostedt 1 2.94% 1 50.00%
Total 34 100.00% 2 100.00%



static int graph_trace_init(struct trace_array *tr)
{
	int ret;

	set_graph_array(tr);
	if (tracing_thresh)
		ret = register_ftrace_graph(&trace_graph_thresh_return,
					    &trace_graph_entry);
	else
		ret = register_ftrace_graph(&trace_graph_return,
					    &trace_graph_entry);
	if (ret)
		return ret;
	tracing_start_cmdline_record();

	return 0;
}

Contributors
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Frédéric Weisbecker 30 50.85% 4 57.14%
Tim Bird 15 25.42% 1 14.29%
Steven Rostedt 13 22.03% 1 14.29%
Joel A Fernandes 1 1.69% 1 14.29%
Total 59 100.00% 7 100.00%



static void graph_trace_reset(struct trace_array *tr)
{
	tracing_stop_cmdline_record();
	unregister_ftrace_graph();
}

Contributors
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Frédéric Weisbecker 14 82.35% 1 50.00%
Steven Rostedt 3 17.65% 1 50.00%
Total 17 100.00% 2 100.00%



static int graph_trace_update_thresh(struct trace_array *tr)
{
	graph_trace_reset(tr);
	return graph_trace_init(tr);
}

Contributors
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Stanislav Fomichev 21 95.45% 1 50.00%
Steven Rostedt 1 4.55% 1 50.00%
Total 22 100.00% 2 100.00%


static int max_bytes_for_cpu;



static void print_graph_cpu(struct trace_seq *s, int cpu)
{
	/*
         * Start with a space character - to make it stand out
         * to the right a bit when trace output is pasted into
         * email:
         */
	trace_seq_printf(s, " %*d) ", max_bytes_for_cpu, cpu);
}

Contributors
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Frédéric Weisbecker 17 65.38% 1 25.00%
Ingo Molnar 5 19.23% 1 25.00%
Steven Rostedt 2 7.69% 1 25.00%
Lai Jiangshan 2 7.69% 1 25.00%
Total 26 100.00% 4 100.00%


#define TRACE_GRAPH_PROCINFO_LENGTH	14



static void print_graph_proc(struct trace_seq *s, pid_t pid)
{
	char comm[TASK_COMM_LEN];
	/* sign + log10(MAX_INT) + '\0' */
	char pid_str[11];
	int spaces = 0;
	int len;
	int i;

	trace_find_cmdline(pid, comm);
	comm[7] = '\0';
	sprintf(pid_str, "%d", pid);

	/* 1 stands for the "-" character */
	len = strlen(comm) + strlen(pid_str) + 1;

	if (len < TRACE_GRAPH_PROCINFO_LENGTH)
		spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;

	/* First spaces to align center */
	for (i = 0; i < spaces / 2; i++)
		trace_seq_putc(s, ' ');

	trace_seq_printf(s, "%s-%s", comm, pid_str);

	/* Last spaces to align center */
	for (i = 0; i < spaces - (spaces / 2); i++)
		trace_seq_putc(s, ' ');
}


Contributors
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Frédéric Weisbecker 130 87.25% 1 25.00%
Steven Rostedt 15 10.07% 2 50.00%
Jovi Zhangwei 4 2.68% 1 25.00%
Total 149 100.00% 4 100.00%



static void print_graph_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
{
	trace_seq_putc(s, ' ');
	trace_print_lat_fmt(s, entry);
}

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Steven Rostedt 30 100.00% 4 100.00%
Total 30 100.00% 4 100.00%

/* If the pid changed since the last trace, output this event */

static void

verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
{
	pid_t prev_pid;
	pid_t *last_pid;

	if (!data)
		return;

	last_pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);

	if (*last_pid == pid)
		return;

	prev_pid = *last_pid;
	*last_pid = pid;

	if (prev_pid == -1)
		return;
/*
 * Context-switch trace line:

 ------------------------------------------
 | 1)  migration/0--1  =>  sshd-1755
 ------------------------------------------

 */
	trace_seq_puts(s, " ------------------------------------------\n");
	print_graph_cpu(s, cpu);
	print_graph_proc(s, prev_pid);
	trace_seq_puts(s, " => ");
	print_graph_proc(s, pid);
	trace_seq_puts(s, "\n ------------------------------------------\n\n");
}

Contributors
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Frédéric Weisbecker 76 63.33% 6 50.00%
Ingo Molnar 21 17.50% 1 8.33%
Steven Rostedt 18 15.00% 3 25.00%
Jovi Zhangwei 3 2.50% 1 8.33%
Jiri Olsa 2 1.67% 1 8.33%
Total 120 100.00% 12 100.00%


static struct ftrace_graph_ret_entry *

get_return_for_leaf(struct trace_iterator *iter,
		struct ftrace_graph_ent_entry *curr)
{
	struct fgraph_data *data = iter->private;
	struct ring_buffer_iter *ring_iter = NULL;
	struct ring_buffer_event *event;
	struct ftrace_graph_ret_entry *next;

	/*
         * If the previous output failed to write to the seq buffer,
         * then we just reuse the data from before.
         */
	if (data && data->failed) {
		curr = &data->ent;
		next = &data->ret;
	} else {

		ring_iter = trace_buffer_iter(iter, iter->cpu);

		/* First peek to compare current entry and the next one */
		if (ring_iter)
			event = ring_buffer_iter_peek(ring_iter, NULL);
		else {
			/*
                         * We need to consume the current entry to see
                         * the next one.
                         */
			ring_buffer_consume(iter->trace_buffer->buffer, iter->cpu,
					    NULL, NULL);
			event = ring_buffer_peek(iter->trace_buffer->buffer, iter->cpu,
						 NULL, NULL);
		}

		if (!event)
			return NULL;

		next = ring_buffer_event_data(event);

		if (data) {
			/*
                         * Save current and next entries for later reference
                         * if the output fails.
                         */
			data->ent = *curr;
			/*
                         * If the next event is not a return type, then
                         * we only care about what type it is. Otherwise we can
                         * safely copy the entire event.
                         */
			if (next->ent.type == TRACE_GRAPH_RET)
				data->ret = *next;
			else
				data->ret.ent.type = next->ent.type;
		}
	}

	if (next->ent.type != TRACE_GRAPH_RET)
		return NULL;

	if (curr->ent.pid != next->ent.pid ||
			curr->graph_ent.func != next->ret.func)
		return NULL;

	/* this is a leaf, now advance the iterator */
	if (ring_iter)
		ring_buffer_read(ring_iter, NULL);

	return next;
}

Contributors
Person Tokens Prop Commits CommitProp
Frédéric Weisbecker 159 62.11% 3 37.50%
Jiri Olsa 61 23.83% 1 12.50%
David Shaohua Li 26 10.16% 1 12.50%
Steven Rostedt 10 3.91% 3 37.50%
Total 256 100.00% 8 100.00%



static void print_graph_abs_time(u64 t, struct trace_seq *s)
{
	unsigned long usecs_rem;

	usecs_rem = do_div(t, NSEC_PER_SEC);
	usecs_rem /= 1000;

	trace_seq_printf(s, "%5lu.%06lu |  ",
			 (unsigned long)t, usecs_rem);
}

Contributors
Person Tokens Prop Commits CommitProp
Frédéric Weisbecker 44 95.65% 1 50.00%
Steven Rostedt 2 4.35% 1 50.00%
Total 46 100.00% 2 100.00%


static void

print_graph_irq(struct trace_iterator *iter, unsigned long addr,
		enum trace_type type, int cpu, pid_t pid, u32 flags)
{
	struct trace_array *tr = iter->tr;
	struct trace_seq *s = &iter->seq;
	struct trace_entry *ent = iter->ent;

	if (addr < (unsigned long)__irqentry_text_start ||
		addr >= (unsigned long)__irqentry_text_end)
		return;

	if (tr->trace_flags & TRACE_ITER_CONTEXT_INFO) {
		/* Absolute time */
		if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
			print_graph_abs_time(iter->ts, s);

		/* Cpu */
		if (flags & TRACE_GRAPH_PRINT_CPU)
			print_graph_cpu(s, cpu);

		/* Proc */
		if (flags & TRACE_GRAPH_PRINT_PROC) {
			print_graph_proc(s,
Person	Tokens	Prop	Commits	CommitProp
Steven Rostedt	10	100.00%	1	100.00%
Total	10	100.00%	1	100.00%
cregit-Linux how code gets into the kernel

Release 4.15 kernel/trace/trace_functions_graph.c

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