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WSL2-Linux-Kernel/kernel/trace/trace_functions_graph.c

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C
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// 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;
}
/**
* 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;
}
/* 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;
}
/* 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;
}
/*
* 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;
}
/**
* 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;
}
#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;
}
#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;
}
static inline int ftrace_graph_ignore_irqs(void)
{
if (!ftrace_graph_skip_irqs || trace_recursion_test(TRACE_IRQ_BIT))
return 0;
return in_irq();
}
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;
}
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);
}
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);
}
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);
}
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);
}
void set_graph_array(struct trace_array *tr)
{
graph_array = tr;
/* Make graph_array visible before we start tracing */
smp_mb();
}
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);
}
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;
}
static void graph_trace_reset(struct trace_array *tr)
{
tracing_stop_cmdline_record();
unregister_ftrace_graph();
}
static int graph_trace_update_thresh(struct trace_array *tr)
{
graph_trace_reset(tr);
return graph_trace_init(tr);
}
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);
}
#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, ' ');
}
static void print_graph_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
{
trace_seq_putc(s, ' ');
trace_print_lat_fmt(s, entry);
}
/* 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");
}
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;
}
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);
}
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, pid);
trace_seq_puts(s, " | ");
}
/* Latency format */
if (tr->trace_flags & TRACE_ITER_LATENCY_FMT)
print_graph_lat_fmt(s, ent);
}
/* No overhead */
print_graph_duration(tr, 0, s, flags | FLAGS_FILL_START);
if (type == TRACE_GRAPH_ENT)
trace_seq_puts(s, "==========>");
else
trace_seq_puts(s, "<==========");
print_graph_duration(tr, 0, s, flags | FLAGS_FILL_END);
trace_seq_putc(s, '\n');
}
void
trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
{
unsigned long nsecs_rem = do_div(duration, 1000);
/* log10(ULONG_MAX) + '\0' */
char usecs_str[21];
char nsecs_str[5];
int len;
int i;
sprintf(usecs_str, "%lu", (unsigned long) duration);
/* Print msecs */
trace_seq_printf(s, "%s", usecs_str);
len = strlen(usecs_str);
/* Print nsecs (we don't want to exceed 7 numbers) */
if (len < 7) {
size_t slen = min_t(size_t, sizeof(nsecs_str), 8UL - len);
snprintf(nsecs_str, slen, "%03lu", nsecs_rem);
trace_seq_printf(s, ".%s", nsecs_str);
len += strlen(nsecs_str) + 1;
}
trace_seq_puts(s, " us ");
/* Print remaining spaces to fit the row's width */
for (i = len; i < 8; i++)
trace_seq_putc(s, ' ');
}
static void
print_graph_duration(struct trace_array *tr, unsigned long long duration,
struct trace_seq *s, u32 flags)
{
if (!(flags & TRACE_GRAPH_PRINT_DURATION) ||
!(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
return;
/* No real adata, just filling the column with spaces */
switch (flags & TRACE_GRAPH_PRINT_FILL_MASK) {
case FLAGS_FILL_FULL:
trace_seq_puts(s, " | ");
return;
case FLAGS_FILL_START:
trace_seq_puts(s, " ");
return;
case FLAGS_FILL_END:
trace_seq_puts(s, " |");
return;
}
/* Signal a overhead of time execution to the output */
if (flags & TRACE_GRAPH_PRINT_OVERHEAD)
trace_seq_printf(s, "%c ", trace_find_mark(duration));
else
trace_seq_puts(s, " ");
trace_print_graph_duration(duration, s);
trace_seq_puts(s, "| ");
}
/* Case of a leaf function on its call entry */
static enum print_line_t
print_graph_entry_leaf(struct trace_iterator *iter,
struct ftrace_graph_ent_entry *entry,
struct ftrace_graph_ret_entry *ret_entry,
struct trace_seq *s, u32 flags)
{
struct fgraph_data *data = iter->private;
struct trace_array *tr = iter->tr;
struct ftrace_graph_ret *graph_ret;
struct ftrace_graph_ent *call;
unsigned long long duration;
int i;
graph_ret = &ret_entry->ret;
call = &entry->graph_ent;
duration = graph_ret->rettime - graph_ret->calltime;
if (data) {
struct fgraph_cpu_data *cpu_data;
int cpu = iter->cpu;
cpu_data = per_cpu_ptr(data->cpu_data, cpu);
/* If a graph tracer ignored set_graph_notrace */
if (call->depth < -1)
call->depth += FTRACE_NOTRACE_DEPTH;
/*
* Comments display at + 1 to depth. Since
* this is a leaf function, keep the comments
* equal to this depth.
*/
cpu_data->depth = call->depth - 1;
/* No need to keep this function around for this depth */
if (call->depth < FTRACE_RETFUNC_DEPTH &&
!WARN_ON_ONCE(call->depth < 0))
cpu_data->enter_funcs[call->depth] = 0;
}
/* Overhead and duration */
print_graph_duration(tr, duration, s, flags);
/* Function */
for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
trace_seq_putc(s, ' ');
trace_seq_printf(s, "%ps();\n", (void *)call->func);
return trace_handle_return(s);
}
static enum print_line_t
print_graph_entry_nested(struct trace_iterator *iter,
struct ftrace_graph_ent_entry *entry,
struct trace_seq *s, int cpu, u32 flags)
{
struct ftrace_graph_ent *call = &entry->graph_ent;
struct fgraph_data *data = iter->private;
struct trace_array *tr = iter->tr;
int i;
if (data) {
struct fgraph_cpu_data *cpu_data;
int cpu = iter->cpu;
/* If a graph tracer ignored set_graph_notrace */
if (call->depth < -1)
call->depth += FTRACE_NOTRACE_DEPTH;
cpu_data = per_cpu_ptr(data->cpu_data, cpu);
cpu_data->depth = call->depth;
/* Save this function pointer to see if the exit matches */
if (call->depth < FTRACE_RETFUNC_DEPTH &&
!WARN_ON_ONCE(call->depth < 0))
cpu_data->enter_funcs[call->depth] = call->func;
}
/* No time */
print_graph_duration(tr, 0, s, flags | FLAGS_FILL_FULL);
/* Function */
for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
trace_seq_putc(s, ' ');
trace_seq_printf(s, "%ps() {\n", (void *)call->func);
if (trace_seq_has_overflowed(s))
return TRACE_TYPE_PARTIAL_LINE;
/*
* we already consumed the current entry to check the next one
* and see if this is a leaf.
*/
return TRACE_TYPE_NO_CONSUME;
}
static void
print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
int type, unsigned long addr, u32 flags)
{
struct fgraph_data *data = iter->private;
struct trace_entry *ent = iter->ent;
struct trace_array *tr = iter->tr;
int cpu = iter->cpu;
/* Pid */
verif_pid(s, ent->pid, cpu, data);
if (type)
/* Interrupt */
print_graph_irq(iter, addr, type, cpu, ent->pid, flags);
if (!(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
return;
/* 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, ent->pid);
trace_seq_puts(s, " | ");
}
/* Latency format */
if (tr->trace_flags & TRACE_ITER_LATENCY_FMT)
print_graph_lat_fmt(s, ent);
return;
}
/*
* Entry check for irq code
*
* returns 1 if
* - we are inside irq code
* - we just entered irq code
*
* retunns 0 if
* - funcgraph-interrupts option is set
* - we are not inside irq code
*/
static int
check_irq_entry(struct trace_iterator *iter, u32 flags,
unsigned long addr, int depth)
{
int cpu = iter->cpu;
int *depth_irq;
struct fgraph_data *data = iter->private;
/*
* If we are either displaying irqs, or we got called as
* a graph event and private data does not exist,
* then we bypass the irq check.
*/
if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
(!data))
return 0;
depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
/*
* We are inside the irq code
*/
if (*depth_irq >= 0)
return 1;
if ((addr < (unsigned long)__irqentry_text_start) ||
(addr >= (unsigned long)__irqentry_text_end))
return 0;
/*
* We are entering irq code.
*/
*depth_irq = depth;
return 1;
}
/*
* Return check for irq code
*
* returns 1 if
* - we are inside irq code
* - we just left irq code
*
* returns 0 if
* - funcgraph-interrupts option is set
* - we are not inside irq code
*/
static int
check_irq_return(struct trace_iterator *iter, u32 flags, int depth)
{
int cpu = iter->cpu;
int *depth_irq;
struct fgraph_data *data = iter->private;
/*
* If we are either displaying irqs, or we got called as
* a graph event and private data does not exist,
* then we bypass the irq check.
*/
if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
(!data))
return 0;
depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
/*
* We are not inside the irq code.
*/
if (*depth_irq == -1)
return 0;
/*
* We are inside the irq code, and this is returning entry.
* Let's not trace it and clear the entry depth, since
* we are out of irq code.
*
* This condition ensures that we 'leave the irq code' once
* we are out of the entry depth. Thus protecting us from
* the RETURN entry loss.
*/
if (*depth_irq >= depth) {
*depth_irq = -1;
return 1;
}
/*
* We are inside the irq code, and this is not the entry.
*/
return 1;
}
static enum print_line_t
print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
struct trace_iterator *iter, u32 flags)
{
struct fgraph_data *data = iter->private;
struct ftrace_graph_ent *call = &field->graph_ent;
struct ftrace_graph_ret_entry *leaf_ret;
static enum print_line_t ret;
int cpu = iter->cpu;
if (check_irq_entry(iter, flags, call->func, call->depth))
return TRACE_TYPE_HANDLED;
print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func, flags);
leaf_ret = get_return_for_leaf(iter, field);
if (leaf_ret)
ret = print_graph_entry_leaf(iter, field, leaf_ret, s, flags);
else
ret = print_graph_entry_nested(iter, field, s, cpu, flags);
if (data) {
/*
* If we failed to write our output, then we need to make
* note of it. Because we already consumed our entry.
*/
if (s->full) {
data->failed = 1;
data->cpu = cpu;
} else
data->failed = 0;
}
return ret;
}
static enum print_line_t
print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
struct trace_entry *ent, struct trace_iterator *iter,
u32 flags)
{
unsigned long long duration = trace->rettime - trace->calltime;
struct fgraph_data *data = iter->private;
struct trace_array *tr = iter->tr;
pid_t pid = ent->pid;
int cpu = iter->cpu;
int func_match = 1;
int i;
if (check_irq_return(iter, flags, trace->depth))
return TRACE_TYPE_HANDLED;
if (data) {
struct fgraph_cpu_data *cpu_data;
int cpu = iter->cpu;
cpu_data = per_cpu_ptr(data->cpu_data, cpu);
/*
* Comments display at + 1 to depth. This is the
* return from a function, we now want the comments
* to display at the same level of the bracket.
*/
cpu_data->depth = trace->depth - 1;
if (trace->depth < FTRACE_RETFUNC_DEPTH &&
!WARN_ON_ONCE(trace->depth < 0)) {
if (cpu_data->enter_funcs[trace->depth] != trace->func)
func_match = 0;
cpu_data->enter_funcs[trace->depth] = 0;
}
}
print_graph_prologue(iter, s, 0, 0, flags);
/* Overhead and duration */
print_graph_duration(tr, duration, s, flags);
/* Closing brace */
for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++)
trace_seq_putc(s, ' ');
/*
* If the return function does not have a matching entry,
* then the entry was lost. Instead of just printing
* the '}' and letting the user guess what function this
* belongs to, write out the function name. Always do
* that if the funcgraph-tail option is enabled.
*/
if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL))
trace_seq_puts(s, "}\n");
else
trace_seq_printf(s, "} /* %ps */\n", (void *)trace->func);
/* Overrun */
if (flags & TRACE_GRAPH_PRINT_OVERRUN)
trace_seq_printf(s, " (Overruns: %lu)\n",
trace->overrun);
print_graph_irq(iter, trace->func, TRACE_GRAPH_RET,
cpu, pid, flags);
return trace_handle_return(s);
}
static enum print_line_t
print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
struct trace_iterator *iter, u32 flags)
{
struct trace_array *tr = iter->tr;
unsigned long sym_flags = (tr->trace_flags & TRACE_ITER_SYM_MASK);
struct fgraph_data *data = iter->private;
struct trace_event *event;
int depth = 0;
int ret;
int i;
if (data)
depth = per_cpu_ptr(data->cpu_data, iter->cpu)->depth;
print_graph_prologue(iter, s, 0, 0, flags);
/* No time */
print_graph_duration(tr, 0, s, flags | FLAGS_FILL_FULL);
/* Indentation */
if (depth > 0)
for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++)
trace_seq_putc(s, ' ');
/* The comment */
trace_seq_puts(s, "/* ");
switch (iter->ent->type) {
case TRACE_BPUTS:
ret = trace_print_bputs_msg_only(iter);
if (ret != TRACE_TYPE_HANDLED)
return ret;
break;
case TRACE_BPRINT:
ret = trace_print_bprintk_msg_only(iter);
if (ret != TRACE_TYPE_HANDLED)
return ret;
break;
case TRACE_PRINT:
ret = trace_print_printk_msg_only(iter);
if (ret != TRACE_TYPE_HANDLED)
return ret;
break;
default:
event = ftrace_find_event(ent->type);
if (!event)
return TRACE_TYPE_UNHANDLED;
ret = event->funcs->trace(iter, sym_flags, event);
if (ret != TRACE_TYPE_HANDLED)
return ret;
}
if (trace_seq_has_overflowed(s))
goto out;
/* Strip ending newline */
if (s->buffer[s->seq.len - 1] == '\n') {
s->buffer[s->seq.len - 1] = '\0';
s->seq.len--;
}
trace_seq_puts(s, " */\n");
out:
return trace_handle_return(s);
}
enum print_line_t
print_graph_function_flags(struct trace_iterator *iter, u32 flags)
{
struct ftrace_graph_ent_entry *field;
struct fgraph_data *data = iter->private;
struct trace_entry *entry = iter->ent;
struct trace_seq *s = &iter->seq;
int cpu = iter->cpu;
int ret;
if (data && per_cpu_ptr(data->cpu_data, cpu)->ignore) {
per_cpu_ptr(data->cpu_data, cpu)->ignore = 0;
return TRACE_TYPE_HANDLED;
}
/*
* If the last output failed, there's a possibility we need
* to print out the missing entry which would never go out.
*/
if (data && data->failed) {
field = &data->ent;
iter->cpu = data->cpu;
ret = print_graph_entry(field, s, iter, flags);
if (ret == TRACE_TYPE_HANDLED && iter->cpu != cpu) {
per_cpu_ptr(data->cpu_data, iter->cpu)->ignore = 1;
ret = TRACE_TYPE_NO_CONSUME;
}
iter->cpu = cpu;
return ret;
}
switch (entry->type) {
case TRACE_GRAPH_ENT: {
/*
* print_graph_entry() may consume the current event,
* thus @field may become invalid, so we need to save it.
* sizeof(struct ftrace_graph_ent_entry) is very small,
* it can be safely saved at the stack.
*/
struct ftrace_graph_ent_entry saved;
trace_assign_type(field, entry);
saved = *field;
return print_graph_entry(&saved, s, iter, flags);
}
case TRACE_GRAPH_RET: {
struct ftrace_graph_ret_entry *field;
trace_assign_type(field, entry);
return print_graph_return(&field->ret, s, entry, iter, flags);
}
case TRACE_STACK:
case TRACE_FN:
/* dont trace stack and functions as comments */
return TRACE_TYPE_UNHANDLED;
default:
return print_graph_comment(s, entry, iter, flags);
}
return TRACE_TYPE_HANDLED;
}
static enum print_line_t
print_graph_function(struct trace_iterator *iter)
{
return print_graph_function_flags(iter, tracer_flags.val);
}
static enum print_line_t
print_graph_function_event(struct trace_iterator *iter, int flags,
struct trace_event *event)
{
return print_graph_function(iter);
}
static void print_lat_header(struct seq_file *s, u32 flags)
{
static const char spaces[] = " " /* 16 spaces */
" " /* 4 spaces */
" "; /* 17 spaces */
int size = 0;
if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
size += 16;
if (flags & TRACE_GRAPH_PRINT_CPU)
size += 4;
if (flags & TRACE_GRAPH_PRINT_PROC)
size += 17;
seq_printf(s, "#%.*s _-----=> irqs-off \n", size, spaces);
seq_printf(s, "#%.*s / _----=> need-resched \n", size, spaces);
seq_printf(s, "#%.*s| / _---=> hardirq/softirq \n", size, spaces);
seq_printf(s, "#%.*s|| / _--=> preempt-depth \n", size, spaces);
seq_printf(s, "#%.*s||| / \n", size, spaces);
}
static void __print_graph_headers_flags(struct trace_array *tr,
struct seq_file *s, u32 flags)
{
int lat = tr->trace_flags & TRACE_ITER_LATENCY_FMT;
if (lat)
print_lat_header(s, flags);
/* 1st line */
seq_putc(s, '#');
if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
seq_puts(s, " TIME ");
if (flags & TRACE_GRAPH_PRINT_CPU)
seq_puts(s, " CPU");
if (flags & TRACE_GRAPH_PRINT_PROC)
seq_puts(s, " TASK/PID ");
if (lat)
seq_puts(s, "||||");
if (flags & TRACE_GRAPH_PRINT_DURATION)
seq_puts(s, " DURATION ");
seq_puts(s, " FUNCTION CALLS\n");
/* 2nd line */
seq_putc(s, '#');
if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
seq_puts(s, " | ");
if (flags & TRACE_GRAPH_PRINT_CPU)
seq_puts(s, " | ");
if (flags & TRACE_GRAPH_PRINT_PROC)
seq_puts(s, " | | ");
if (lat)
seq_puts(s, "||||");
if (flags & TRACE_GRAPH_PRINT_DURATION)
seq_puts(s, " | | ");
seq_puts(s, " | | | |\n");
}
static void print_graph_headers(struct seq_file *s)
{
print_graph_headers_flags(s, tracer_flags.val);
}
void print_graph_headers_flags(struct seq_file *s, u32 flags)
{
struct trace_iterator *iter = s->private;
struct trace_array *tr = iter->tr;
if (!(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
return;
if (tr->trace_flags & TRACE_ITER_LATENCY_FMT) {
/* print nothing if the buffers are empty */
if (trace_empty(iter))
return;
print_trace_header(s, iter);
}
__print_graph_headers_flags(tr, s, flags);
}
void graph_trace_open(struct trace_iterator *iter)
{
/* pid and depth on the last trace processed */
struct fgraph_data *data;
gfp_t gfpflags;
int cpu;
iter->private = NULL;
/* We can be called in atomic context via ftrace_dump() */
gfpflags = (in_atomic() || irqs_disabled()) ? GFP_ATOMIC : GFP_KERNEL;
data = kzalloc(sizeof(*data), gfpflags);
if (!data)
goto out_err;
data->cpu_data = alloc_percpu_gfp(struct fgraph_cpu_data, gfpflags);
if (!data->cpu_data)
goto out_err_free;
for_each_possible_cpu(cpu) {
pid_t *pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);
int *depth = &(per_cpu_ptr(data->cpu_data, cpu)->depth);
int *ignore = &(per_cpu_ptr(data->cpu_data, cpu)->ignore);
int *depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
*pid = -1;
*depth = 0;
*ignore = 0;
*depth_irq = -1;
}
iter->private = data;
return;
out_err_free:
kfree(data);
out_err:
pr_warn("function graph tracer: not enough memory\n");
}
void graph_trace_close(struct trace_iterator *iter)
{
struct fgraph_data *data = iter->private;
if (data) {
free_percpu(data->cpu_data);
kfree(data);
}
}
static int
func_graph_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
{
if (bit == TRACE_GRAPH_PRINT_IRQS)
ftrace_graph_skip_irqs = !set;
if (bit == TRACE_GRAPH_SLEEP_TIME)
ftrace_graph_sleep_time_control(set);
if (bit == TRACE_GRAPH_GRAPH_TIME)
ftrace_graph_graph_time_control(set);
return 0;
}
static struct trace_event_functions graph_functions = {
.trace = print_graph_function_event,
};
static struct trace_event graph_trace_entry_event = {
.type = TRACE_GRAPH_ENT,
.funcs = &graph_functions,
};
static struct trace_event graph_trace_ret_event = {
.type = TRACE_GRAPH_RET,
.funcs = &graph_functions
};
static struct tracer graph_trace __tracer_data = {
.name = "function_graph",
.update_thresh = graph_trace_update_thresh,
.open = graph_trace_open,
.pipe_open = graph_trace_open,
.close = graph_trace_close,
.pipe_close = graph_trace_close,
.init = graph_trace_init,
.reset = graph_trace_reset,
.print_line = print_graph_function,
.print_header = print_graph_headers,
.flags = &tracer_flags,
.set_flag = func_graph_set_flag,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_function_graph,
#endif
};
static ssize_t
graph_depth_write(struct file *filp, const char __user *ubuf, size_t cnt,
loff_t *ppos)
{
unsigned long val;
int ret;
ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
if (ret)
return ret;
fgraph_max_depth = val;
*ppos += cnt;
return cnt;
}
static ssize_t
graph_depth_read(struct file *filp, char __user *ubuf, size_t cnt,
loff_t *ppos)
{
char buf[15]; /* More than enough to hold UINT_MAX + "\n"*/
int n;
n = sprintf(buf, "%d\n", fgraph_max_depth);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, n);
}
static const struct file_operations graph_depth_fops = {
.open = tracing_open_generic,
.write = graph_depth_write,
.read = graph_depth_read,
.llseek = generic_file_llseek,
};
static __init int init_graph_tracefs(void)
{
struct dentry *d_tracer;
d_tracer = tracing_init_dentry();
if (IS_ERR(d_tracer))
return 0;
trace_create_file("max_graph_depth", 0644, d_tracer,
NULL, &graph_depth_fops);
return 0;
}
fs_initcall(init_graph_tracefs);
static __init int init_graph_trace(void)
{
max_bytes_for_cpu = snprintf(NULL, 0, "%u", nr_cpu_ids - 1);
if (!register_trace_event(&graph_trace_entry_event)) {
pr_warn("Warning: could not register graph trace events\n");
return 1;
}
if (!register_trace_event(&graph_trace_ret_event)) {
pr_warn("Warning: could not register graph trace events\n");
return 1;
}
return register_tracer(&graph_trace);
}
core_initcall(init_graph_trace);
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