2
0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-25 21:54:06 +08:00
linux-next/kernel/trace/trace_sched_wakeup.c
Steven Rostedt (VMware) 1329249437 tracing: Make struct ring_buffer less ambiguous
As there's two struct ring_buffers in the kernel, it causes some confusion.
The other one being the perf ring buffer. It was agreed upon that as neither
of the ring buffers are generic enough to be used globally, they should be
renamed as:

   perf's ring_buffer -> perf_buffer
   ftrace's ring_buffer -> trace_buffer

This implements the changes to the ring buffer that ftrace uses.

Link: https://lore.kernel.org/r/20191213140531.116b3200@gandalf.local.home

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-01-13 13:19:38 -05:00

823 lines
20 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* trace task wakeup timings
*
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
*
* Based on code from the latency_tracer, that is:
*
* Copyright (C) 2004-2006 Ingo Molnar
* Copyright (C) 2004 Nadia Yvette Chambers
*/
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/sched/rt.h>
#include <linux/sched/deadline.h>
#include <trace/events/sched.h>
#include "trace.h"
static struct trace_array *wakeup_trace;
static int __read_mostly tracer_enabled;
static struct task_struct *wakeup_task;
static int wakeup_cpu;
static int wakeup_current_cpu;
static unsigned wakeup_prio = -1;
static int wakeup_rt;
static int wakeup_dl;
static int tracing_dl = 0;
static arch_spinlock_t wakeup_lock =
(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
static void wakeup_reset(struct trace_array *tr);
static void __wakeup_reset(struct trace_array *tr);
static int start_func_tracer(struct trace_array *tr, int graph);
static void stop_func_tracer(struct trace_array *tr, int graph);
static int save_flags;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
# define is_graph(tr) ((tr)->trace_flags & TRACE_ITER_DISPLAY_GRAPH)
#else
# define is_graph(tr) false
#endif
#ifdef CONFIG_FUNCTION_TRACER
static bool function_enabled;
/*
* Prologue for the wakeup function tracers.
*
* Returns 1 if it is OK to continue, and preemption
* is disabled and data->disabled is incremented.
* 0 if the trace is to be ignored, and preemption
* is not disabled and data->disabled is
* kept the same.
*
* Note, this function is also used outside this ifdef but
* inside the #ifdef of the function graph tracer below.
* This is OK, since the function graph tracer is
* dependent on the function tracer.
*/
static int
func_prolog_preempt_disable(struct trace_array *tr,
struct trace_array_cpu **data,
int *pc)
{
long disabled;
int cpu;
if (likely(!wakeup_task))
return 0;
*pc = preempt_count();
preempt_disable_notrace();
cpu = raw_smp_processor_id();
if (cpu != wakeup_current_cpu)
goto out_enable;
*data = per_cpu_ptr(tr->array_buffer.data, cpu);
disabled = atomic_inc_return(&(*data)->disabled);
if (unlikely(disabled != 1))
goto out;
return 1;
out:
atomic_dec(&(*data)->disabled);
out_enable:
preempt_enable_notrace();
return 0;
}
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static int wakeup_display_graph(struct trace_array *tr, int set)
{
if (!(is_graph(tr) ^ set))
return 0;
stop_func_tracer(tr, !set);
wakeup_reset(wakeup_trace);
tr->max_latency = 0;
return start_func_tracer(tr, set);
}
static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
{
struct trace_array *tr = wakeup_trace;
struct trace_array_cpu *data;
unsigned long flags;
int pc, ret = 0;
if (ftrace_graph_ignore_func(trace))
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;
if (!func_prolog_preempt_disable(tr, &data, &pc))
return 0;
local_save_flags(flags);
ret = __trace_graph_entry(tr, trace, flags, pc);
atomic_dec(&data->disabled);
preempt_enable_notrace();
return ret;
}
static void wakeup_graph_return(struct ftrace_graph_ret *trace)
{
struct trace_array *tr = wakeup_trace;
struct trace_array_cpu *data;
unsigned long flags;
int pc;
ftrace_graph_addr_finish(trace);
if (!func_prolog_preempt_disable(tr, &data, &pc))
return;
local_save_flags(flags);
__trace_graph_return(tr, trace, flags, pc);
atomic_dec(&data->disabled);
preempt_enable_notrace();
return;
}
static struct fgraph_ops fgraph_wakeup_ops = {
.entryfunc = &wakeup_graph_entry,
.retfunc = &wakeup_graph_return,
};
static void wakeup_trace_open(struct trace_iterator *iter)
{
if (is_graph(iter->tr))
graph_trace_open(iter);
}
static void wakeup_trace_close(struct trace_iterator *iter)
{
if (iter->private)
graph_trace_close(iter);
}
#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
TRACE_GRAPH_PRINT_CPU | \
TRACE_GRAPH_PRINT_REL_TIME | \
TRACE_GRAPH_PRINT_DURATION | \
TRACE_GRAPH_PRINT_OVERHEAD | \
TRACE_GRAPH_PRINT_IRQS)
static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
{
/*
* In graph mode call the graph tracer output function,
* otherwise go with the TRACE_FN event handler
*/
if (is_graph(iter->tr))
return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
return TRACE_TYPE_UNHANDLED;
}
static void wakeup_print_header(struct seq_file *s)
{
if (is_graph(wakeup_trace))
print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
else
trace_default_header(s);
}
#endif /* else CONFIG_FUNCTION_GRAPH_TRACER */
/*
* wakeup uses its own tracer function to keep the overhead down:
*/
static void
wakeup_tracer_call(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct pt_regs *pt_regs)
{
struct trace_array *tr = wakeup_trace;
struct trace_array_cpu *data;
unsigned long flags;
int pc;
if (!func_prolog_preempt_disable(tr, &data, &pc))
return;
local_irq_save(flags);
trace_function(tr, ip, parent_ip, flags, pc);
local_irq_restore(flags);
atomic_dec(&data->disabled);
preempt_enable_notrace();
}
static int register_wakeup_function(struct trace_array *tr, int graph, int set)
{
int ret;
/* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
return 0;
if (graph)
ret = register_ftrace_graph(&fgraph_wakeup_ops);
else
ret = register_ftrace_function(tr->ops);
if (!ret)
function_enabled = true;
return ret;
}
static void unregister_wakeup_function(struct trace_array *tr, int graph)
{
if (!function_enabled)
return;
if (graph)
unregister_ftrace_graph(&fgraph_wakeup_ops);
else
unregister_ftrace_function(tr->ops);
function_enabled = false;
}
static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
{
if (!(mask & TRACE_ITER_FUNCTION))
return 0;
if (set)
register_wakeup_function(tr, is_graph(tr), 1);
else
unregister_wakeup_function(tr, is_graph(tr));
return 1;
}
#else /* CONFIG_FUNCTION_TRACER */
static int register_wakeup_function(struct trace_array *tr, int graph, int set)
{
return 0;
}
static void unregister_wakeup_function(struct trace_array *tr, int graph) { }
static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
{
return 0;
}
#endif /* else CONFIG_FUNCTION_TRACER */
#ifndef CONFIG_FUNCTION_GRAPH_TRACER
static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
{
return TRACE_TYPE_UNHANDLED;
}
static void wakeup_trace_open(struct trace_iterator *iter) { }
static void wakeup_trace_close(struct trace_iterator *iter) { }
static void wakeup_print_header(struct seq_file *s)
{
trace_default_header(s);
}
#endif /* !CONFIG_FUNCTION_GRAPH_TRACER */
static void
__trace_function(struct trace_array *tr,
unsigned long ip, unsigned long parent_ip,
unsigned long flags, int pc)
{
if (is_graph(tr))
trace_graph_function(tr, ip, parent_ip, flags, pc);
else
trace_function(tr, ip, parent_ip, flags, pc);
}
static int wakeup_flag_changed(struct trace_array *tr, u32 mask, int set)
{
struct tracer *tracer = tr->current_trace;
if (wakeup_function_set(tr, mask, set))
return 0;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
if (mask & TRACE_ITER_DISPLAY_GRAPH)
return wakeup_display_graph(tr, set);
#endif
return trace_keep_overwrite(tracer, mask, set);
}
static int start_func_tracer(struct trace_array *tr, int graph)
{
int ret;
ret = register_wakeup_function(tr, graph, 0);
if (!ret && tracing_is_enabled())
tracer_enabled = 1;
else
tracer_enabled = 0;
return ret;
}
static void stop_func_tracer(struct trace_array *tr, int graph)
{
tracer_enabled = 0;
unregister_wakeup_function(tr, graph);
}
/*
* Should this new latency be reported/recorded?
*/
static bool report_latency(struct trace_array *tr, u64 delta)
{
if (tracing_thresh) {
if (delta < tracing_thresh)
return false;
} else {
if (delta <= tr->max_latency)
return false;
}
return true;
}
static void
probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)
{
if (task != wakeup_task)
return;
wakeup_current_cpu = cpu;
}
static void
tracing_sched_switch_trace(struct trace_array *tr,
struct task_struct *prev,
struct task_struct *next,
unsigned long flags, int pc)
{
struct trace_event_call *call = &event_context_switch;
struct trace_buffer *buffer = tr->array_buffer.buffer;
struct ring_buffer_event *event;
struct ctx_switch_entry *entry;
event = trace_buffer_lock_reserve(buffer, TRACE_CTX,
sizeof(*entry), flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
entry->prev_pid = prev->pid;
entry->prev_prio = prev->prio;
entry->prev_state = task_state_index(prev);
entry->next_pid = next->pid;
entry->next_prio = next->prio;
entry->next_state = task_state_index(next);
entry->next_cpu = task_cpu(next);
if (!call_filter_check_discard(call, entry, buffer, event))
trace_buffer_unlock_commit(tr, buffer, event, flags, pc);
}
static void
tracing_sched_wakeup_trace(struct trace_array *tr,
struct task_struct *wakee,
struct task_struct *curr,
unsigned long flags, int pc)
{
struct trace_event_call *call = &event_wakeup;
struct ring_buffer_event *event;
struct ctx_switch_entry *entry;
struct trace_buffer *buffer = tr->array_buffer.buffer;
event = trace_buffer_lock_reserve(buffer, TRACE_WAKE,
sizeof(*entry), flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
entry->prev_pid = curr->pid;
entry->prev_prio = curr->prio;
entry->prev_state = task_state_index(curr);
entry->next_pid = wakee->pid;
entry->next_prio = wakee->prio;
entry->next_state = task_state_index(wakee);
entry->next_cpu = task_cpu(wakee);
if (!call_filter_check_discard(call, entry, buffer, event))
trace_buffer_unlock_commit(tr, buffer, event, flags, pc);
}
static void notrace
probe_wakeup_sched_switch(void *ignore, bool preempt,
struct task_struct *prev, struct task_struct *next)
{
struct trace_array_cpu *data;
u64 T0, T1, delta;
unsigned long flags;
long disabled;
int cpu;
int pc;
tracing_record_cmdline(prev);
if (unlikely(!tracer_enabled))
return;
/*
* When we start a new trace, we set wakeup_task to NULL
* and then set tracer_enabled = 1. We want to make sure
* that another CPU does not see the tracer_enabled = 1
* and the wakeup_task with an older task, that might
* actually be the same as next.
*/
smp_rmb();
if (next != wakeup_task)
return;
pc = preempt_count();
/* disable local data, not wakeup_cpu data */
cpu = raw_smp_processor_id();
disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
if (likely(disabled != 1))
goto out;
local_irq_save(flags);
arch_spin_lock(&wakeup_lock);
/* We could race with grabbing wakeup_lock */
if (unlikely(!tracer_enabled || next != wakeup_task))
goto out_unlock;
/* The task we are waiting for is waking up */
data = per_cpu_ptr(wakeup_trace->array_buffer.data, wakeup_cpu);
__trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
__trace_stack(wakeup_trace, flags, 0, pc);
T0 = data->preempt_timestamp;
T1 = ftrace_now(cpu);
delta = T1-T0;
if (!report_latency(wakeup_trace, delta))
goto out_unlock;
if (likely(!is_tracing_stopped())) {
wakeup_trace->max_latency = delta;
update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu, NULL);
}
out_unlock:
__wakeup_reset(wakeup_trace);
arch_spin_unlock(&wakeup_lock);
local_irq_restore(flags);
out:
atomic_dec(&per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
}
static void __wakeup_reset(struct trace_array *tr)
{
wakeup_cpu = -1;
wakeup_prio = -1;
tracing_dl = 0;
if (wakeup_task)
put_task_struct(wakeup_task);
wakeup_task = NULL;
}
static void wakeup_reset(struct trace_array *tr)
{
unsigned long flags;
tracing_reset_online_cpus(&tr->array_buffer);
local_irq_save(flags);
arch_spin_lock(&wakeup_lock);
__wakeup_reset(tr);
arch_spin_unlock(&wakeup_lock);
local_irq_restore(flags);
}
static void
probe_wakeup(void *ignore, struct task_struct *p)
{
struct trace_array_cpu *data;
int cpu = smp_processor_id();
unsigned long flags;
long disabled;
int pc;
if (likely(!tracer_enabled))
return;
tracing_record_cmdline(p);
tracing_record_cmdline(current);
/*
* Semantic is like this:
* - wakeup tracer handles all tasks in the system, independently
* from their scheduling class;
* - wakeup_rt tracer handles tasks belonging to sched_dl and
* sched_rt class;
* - wakeup_dl handles tasks belonging to sched_dl class only.
*/
if (tracing_dl || (wakeup_dl && !dl_task(p)) ||
(wakeup_rt && !dl_task(p) && !rt_task(p)) ||
(!dl_task(p) && (p->prio >= wakeup_prio || p->prio >= current->prio)))
return;
pc = preempt_count();
disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
if (unlikely(disabled != 1))
goto out;
/* interrupts should be off from try_to_wake_up */
arch_spin_lock(&wakeup_lock);
/* check for races. */
if (!tracer_enabled || tracing_dl ||
(!dl_task(p) && p->prio >= wakeup_prio))
goto out_locked;
/* reset the trace */
__wakeup_reset(wakeup_trace);
wakeup_cpu = task_cpu(p);
wakeup_current_cpu = wakeup_cpu;
wakeup_prio = p->prio;
/*
* Once you start tracing a -deadline task, don't bother tracing
* another task until the first one wakes up.
*/
if (dl_task(p))
tracing_dl = 1;
else
tracing_dl = 0;
wakeup_task = get_task_struct(p);
local_save_flags(flags);
data = per_cpu_ptr(wakeup_trace->array_buffer.data, wakeup_cpu);
data->preempt_timestamp = ftrace_now(cpu);
tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
__trace_stack(wakeup_trace, flags, 0, pc);
/*
* We must be careful in using CALLER_ADDR2. But since wake_up
* is not called by an assembly function (where as schedule is)
* it should be safe to use it here.
*/
__trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
out_locked:
arch_spin_unlock(&wakeup_lock);
out:
atomic_dec(&per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
}
static void start_wakeup_tracer(struct trace_array *tr)
{
int ret;
ret = register_trace_sched_wakeup(probe_wakeup, NULL);
if (ret) {
pr_info("wakeup trace: Couldn't activate tracepoint"
" probe to kernel_sched_wakeup\n");
return;
}
ret = register_trace_sched_wakeup_new(probe_wakeup, NULL);
if (ret) {
pr_info("wakeup trace: Couldn't activate tracepoint"
" probe to kernel_sched_wakeup_new\n");
goto fail_deprobe;
}
ret = register_trace_sched_switch(probe_wakeup_sched_switch, NULL);
if (ret) {
pr_info("sched trace: Couldn't activate tracepoint"
" probe to kernel_sched_switch\n");
goto fail_deprobe_wake_new;
}
ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
if (ret) {
pr_info("wakeup trace: Couldn't activate tracepoint"
" probe to kernel_sched_migrate_task\n");
goto fail_deprobe_sched_switch;
}
wakeup_reset(tr);
/*
* Don't let the tracer_enabled = 1 show up before
* the wakeup_task is reset. This may be overkill since
* wakeup_reset does a spin_unlock after setting the
* wakeup_task to NULL, but I want to be safe.
* This is a slow path anyway.
*/
smp_wmb();
if (start_func_tracer(tr, is_graph(tr)))
printk(KERN_ERR "failed to start wakeup tracer\n");
return;
fail_deprobe_sched_switch:
unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
fail_deprobe_wake_new:
unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
fail_deprobe:
unregister_trace_sched_wakeup(probe_wakeup, NULL);
}
static void stop_wakeup_tracer(struct trace_array *tr)
{
tracer_enabled = 0;
stop_func_tracer(tr, is_graph(tr));
unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
unregister_trace_sched_wakeup(probe_wakeup, NULL);
unregister_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
}
static bool wakeup_busy;
static int __wakeup_tracer_init(struct trace_array *tr)
{
save_flags = tr->trace_flags;
/* non overwrite screws up the latency tracers */
set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
tr->max_latency = 0;
wakeup_trace = tr;
ftrace_init_array_ops(tr, wakeup_tracer_call);
start_wakeup_tracer(tr);
wakeup_busy = true;
return 0;
}
static int wakeup_tracer_init(struct trace_array *tr)
{
if (wakeup_busy)
return -EBUSY;
wakeup_dl = 0;
wakeup_rt = 0;
return __wakeup_tracer_init(tr);
}
static int wakeup_rt_tracer_init(struct trace_array *tr)
{
if (wakeup_busy)
return -EBUSY;
wakeup_dl = 0;
wakeup_rt = 1;
return __wakeup_tracer_init(tr);
}
static int wakeup_dl_tracer_init(struct trace_array *tr)
{
if (wakeup_busy)
return -EBUSY;
wakeup_dl = 1;
wakeup_rt = 0;
return __wakeup_tracer_init(tr);
}
static void wakeup_tracer_reset(struct trace_array *tr)
{
int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
stop_wakeup_tracer(tr);
/* make sure we put back any tasks we are tracing */
wakeup_reset(tr);
set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
ftrace_reset_array_ops(tr);
wakeup_busy = false;
}
static void wakeup_tracer_start(struct trace_array *tr)
{
wakeup_reset(tr);
tracer_enabled = 1;
}
static void wakeup_tracer_stop(struct trace_array *tr)
{
tracer_enabled = 0;
}
static struct tracer wakeup_tracer __read_mostly =
{
.name = "wakeup",
.init = wakeup_tracer_init,
.reset = wakeup_tracer_reset,
.start = wakeup_tracer_start,
.stop = wakeup_tracer_stop,
.print_max = true,
.print_header = wakeup_print_header,
.print_line = wakeup_print_line,
.flag_changed = wakeup_flag_changed,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_wakeup,
#endif
.open = wakeup_trace_open,
.close = wakeup_trace_close,
.allow_instances = true,
.use_max_tr = true,
};
static struct tracer wakeup_rt_tracer __read_mostly =
{
.name = "wakeup_rt",
.init = wakeup_rt_tracer_init,
.reset = wakeup_tracer_reset,
.start = wakeup_tracer_start,
.stop = wakeup_tracer_stop,
.print_max = true,
.print_header = wakeup_print_header,
.print_line = wakeup_print_line,
.flag_changed = wakeup_flag_changed,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_wakeup,
#endif
.open = wakeup_trace_open,
.close = wakeup_trace_close,
.allow_instances = true,
.use_max_tr = true,
};
static struct tracer wakeup_dl_tracer __read_mostly =
{
.name = "wakeup_dl",
.init = wakeup_dl_tracer_init,
.reset = wakeup_tracer_reset,
.start = wakeup_tracer_start,
.stop = wakeup_tracer_stop,
.print_max = true,
.print_header = wakeup_print_header,
.print_line = wakeup_print_line,
.flag_changed = wakeup_flag_changed,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_wakeup,
#endif
.open = wakeup_trace_open,
.close = wakeup_trace_close,
.allow_instances = true,
.use_max_tr = true,
};
__init static int init_wakeup_tracer(void)
{
int ret;
ret = register_tracer(&wakeup_tracer);
if (ret)
return ret;
ret = register_tracer(&wakeup_rt_tracer);
if (ret)
return ret;
ret = register_tracer(&wakeup_dl_tracer);
if (ret)
return ret;
return 0;
}
core_initcall(init_wakeup_tracer);