linux/kernel/trace/trace_selftest.c
Steven Rostedt (VMware) 726b3d3f14 ftrace: Handle tracing when switching between context
When an interrupt or NMI comes in and switches the context, there's a delay
from when the preempt_count() shows the update. As the preempt_count() is
used to detect recursion having each context have its own bit get set when
tracing starts, and if that bit is already set, it is considered a recursion
and the function exits. But if this happens in that section where context
has changed but preempt_count() has not been updated, this will be
incorrectly flagged as a recursion.

To handle this case, create another bit call TRANSITION and test it if the
current context bit is already set. Flag the call as a recursion if the
TRANSITION bit is already set, and if not, set it and continue. The
TRANSITION bit will be cleared normally on the return of the function that
set it, or if the current context bit is clear, set it and clear the
TRANSITION bit to allow for another transition between the current context
and an even higher one.

Cc: stable@vger.kernel.org
Fixes: edc15cafcb ("tracing: Avoid unnecessary multiple recursion checks")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-11-02 08:52:18 -05:00

1198 lines
26 KiB
C

// SPDX-License-Identifier: GPL-2.0
/* Include in trace.c */
#include <uapi/linux/sched/types.h>
#include <linux/stringify.h>
#include <linux/kthread.h>
#include <linux/delay.h>
#include <linux/slab.h>
static inline int trace_valid_entry(struct trace_entry *entry)
{
switch (entry->type) {
case TRACE_FN:
case TRACE_CTX:
case TRACE_WAKE:
case TRACE_STACK:
case TRACE_PRINT:
case TRACE_BRANCH:
case TRACE_GRAPH_ENT:
case TRACE_GRAPH_RET:
return 1;
}
return 0;
}
static int trace_test_buffer_cpu(struct array_buffer *buf, int cpu)
{
struct ring_buffer_event *event;
struct trace_entry *entry;
unsigned int loops = 0;
while ((event = ring_buffer_consume(buf->buffer, cpu, NULL, NULL))) {
entry = ring_buffer_event_data(event);
/*
* The ring buffer is a size of trace_buf_size, if
* we loop more than the size, there's something wrong
* with the ring buffer.
*/
if (loops++ > trace_buf_size) {
printk(KERN_CONT ".. bad ring buffer ");
goto failed;
}
if (!trace_valid_entry(entry)) {
printk(KERN_CONT ".. invalid entry %d ",
entry->type);
goto failed;
}
}
return 0;
failed:
/* disable tracing */
tracing_disabled = 1;
printk(KERN_CONT ".. corrupted trace buffer .. ");
return -1;
}
/*
* Test the trace buffer to see if all the elements
* are still sane.
*/
static int __maybe_unused trace_test_buffer(struct array_buffer *buf, unsigned long *count)
{
unsigned long flags, cnt = 0;
int cpu, ret = 0;
/* Don't allow flipping of max traces now */
local_irq_save(flags);
arch_spin_lock(&buf->tr->max_lock);
cnt = ring_buffer_entries(buf->buffer);
/*
* The trace_test_buffer_cpu runs a while loop to consume all data.
* If the calling tracer is broken, and is constantly filling
* the buffer, this will run forever, and hard lock the box.
* We disable the ring buffer while we do this test to prevent
* a hard lock up.
*/
tracing_off();
for_each_possible_cpu(cpu) {
ret = trace_test_buffer_cpu(buf, cpu);
if (ret)
break;
}
tracing_on();
arch_spin_unlock(&buf->tr->max_lock);
local_irq_restore(flags);
if (count)
*count = cnt;
return ret;
}
static inline void warn_failed_init_tracer(struct tracer *trace, int init_ret)
{
printk(KERN_WARNING "Failed to init %s tracer, init returned %d\n",
trace->name, init_ret);
}
#ifdef CONFIG_FUNCTION_TRACER
#ifdef CONFIG_DYNAMIC_FTRACE
static int trace_selftest_test_probe1_cnt;
static void trace_selftest_test_probe1_func(unsigned long ip,
unsigned long pip,
struct ftrace_ops *op,
struct pt_regs *pt_regs)
{
trace_selftest_test_probe1_cnt++;
}
static int trace_selftest_test_probe2_cnt;
static void trace_selftest_test_probe2_func(unsigned long ip,
unsigned long pip,
struct ftrace_ops *op,
struct pt_regs *pt_regs)
{
trace_selftest_test_probe2_cnt++;
}
static int trace_selftest_test_probe3_cnt;
static void trace_selftest_test_probe3_func(unsigned long ip,
unsigned long pip,
struct ftrace_ops *op,
struct pt_regs *pt_regs)
{
trace_selftest_test_probe3_cnt++;
}
static int trace_selftest_test_global_cnt;
static void trace_selftest_test_global_func(unsigned long ip,
unsigned long pip,
struct ftrace_ops *op,
struct pt_regs *pt_regs)
{
trace_selftest_test_global_cnt++;
}
static int trace_selftest_test_dyn_cnt;
static void trace_selftest_test_dyn_func(unsigned long ip,
unsigned long pip,
struct ftrace_ops *op,
struct pt_regs *pt_regs)
{
trace_selftest_test_dyn_cnt++;
}
static struct ftrace_ops test_probe1 = {
.func = trace_selftest_test_probe1_func,
.flags = FTRACE_OPS_FL_RECURSION_SAFE,
};
static struct ftrace_ops test_probe2 = {
.func = trace_selftest_test_probe2_func,
.flags = FTRACE_OPS_FL_RECURSION_SAFE,
};
static struct ftrace_ops test_probe3 = {
.func = trace_selftest_test_probe3_func,
.flags = FTRACE_OPS_FL_RECURSION_SAFE,
};
static void print_counts(void)
{
printk("(%d %d %d %d %d) ",
trace_selftest_test_probe1_cnt,
trace_selftest_test_probe2_cnt,
trace_selftest_test_probe3_cnt,
trace_selftest_test_global_cnt,
trace_selftest_test_dyn_cnt);
}
static void reset_counts(void)
{
trace_selftest_test_probe1_cnt = 0;
trace_selftest_test_probe2_cnt = 0;
trace_selftest_test_probe3_cnt = 0;
trace_selftest_test_global_cnt = 0;
trace_selftest_test_dyn_cnt = 0;
}
static int trace_selftest_ops(struct trace_array *tr, int cnt)
{
int save_ftrace_enabled = ftrace_enabled;
struct ftrace_ops *dyn_ops;
char *func1_name;
char *func2_name;
int len1;
int len2;
int ret = -1;
printk(KERN_CONT "PASSED\n");
pr_info("Testing dynamic ftrace ops #%d: ", cnt);
ftrace_enabled = 1;
reset_counts();
/* Handle PPC64 '.' name */
func1_name = "*" __stringify(DYN_FTRACE_TEST_NAME);
func2_name = "*" __stringify(DYN_FTRACE_TEST_NAME2);
len1 = strlen(func1_name);
len2 = strlen(func2_name);
/*
* Probe 1 will trace function 1.
* Probe 2 will trace function 2.
* Probe 3 will trace functions 1 and 2.
*/
ftrace_set_filter(&test_probe1, func1_name, len1, 1);
ftrace_set_filter(&test_probe2, func2_name, len2, 1);
ftrace_set_filter(&test_probe3, func1_name, len1, 1);
ftrace_set_filter(&test_probe3, func2_name, len2, 0);
register_ftrace_function(&test_probe1);
register_ftrace_function(&test_probe2);
register_ftrace_function(&test_probe3);
/* First time we are running with main function */
if (cnt > 1) {
ftrace_init_array_ops(tr, trace_selftest_test_global_func);
register_ftrace_function(tr->ops);
}
DYN_FTRACE_TEST_NAME();
print_counts();
if (trace_selftest_test_probe1_cnt != 1)
goto out;
if (trace_selftest_test_probe2_cnt != 0)
goto out;
if (trace_selftest_test_probe3_cnt != 1)
goto out;
if (cnt > 1) {
if (trace_selftest_test_global_cnt == 0)
goto out;
}
DYN_FTRACE_TEST_NAME2();
print_counts();
if (trace_selftest_test_probe1_cnt != 1)
goto out;
if (trace_selftest_test_probe2_cnt != 1)
goto out;
if (trace_selftest_test_probe3_cnt != 2)
goto out;
/* Add a dynamic probe */
dyn_ops = kzalloc(sizeof(*dyn_ops), GFP_KERNEL);
if (!dyn_ops) {
printk("MEMORY ERROR ");
goto out;
}
dyn_ops->func = trace_selftest_test_dyn_func;
register_ftrace_function(dyn_ops);
trace_selftest_test_global_cnt = 0;
DYN_FTRACE_TEST_NAME();
print_counts();
if (trace_selftest_test_probe1_cnt != 2)
goto out_free;
if (trace_selftest_test_probe2_cnt != 1)
goto out_free;
if (trace_selftest_test_probe3_cnt != 3)
goto out_free;
if (cnt > 1) {
if (trace_selftest_test_global_cnt == 0)
goto out_free;
}
if (trace_selftest_test_dyn_cnt == 0)
goto out_free;
DYN_FTRACE_TEST_NAME2();
print_counts();
if (trace_selftest_test_probe1_cnt != 2)
goto out_free;
if (trace_selftest_test_probe2_cnt != 2)
goto out_free;
if (trace_selftest_test_probe3_cnt != 4)
goto out_free;
ret = 0;
out_free:
unregister_ftrace_function(dyn_ops);
kfree(dyn_ops);
out:
/* Purposely unregister in the same order */
unregister_ftrace_function(&test_probe1);
unregister_ftrace_function(&test_probe2);
unregister_ftrace_function(&test_probe3);
if (cnt > 1)
unregister_ftrace_function(tr->ops);
ftrace_reset_array_ops(tr);
/* Make sure everything is off */
reset_counts();
DYN_FTRACE_TEST_NAME();
DYN_FTRACE_TEST_NAME();
if (trace_selftest_test_probe1_cnt ||
trace_selftest_test_probe2_cnt ||
trace_selftest_test_probe3_cnt ||
trace_selftest_test_global_cnt ||
trace_selftest_test_dyn_cnt)
ret = -1;
ftrace_enabled = save_ftrace_enabled;
return ret;
}
/* Test dynamic code modification and ftrace filters */
static int trace_selftest_startup_dynamic_tracing(struct tracer *trace,
struct trace_array *tr,
int (*func)(void))
{
int save_ftrace_enabled = ftrace_enabled;
unsigned long count;
char *func_name;
int ret;
/* The ftrace test PASSED */
printk(KERN_CONT "PASSED\n");
pr_info("Testing dynamic ftrace: ");
/* enable tracing, and record the filter function */
ftrace_enabled = 1;
/* passed in by parameter to fool gcc from optimizing */
func();
/*
* Some archs *cough*PowerPC*cough* add characters to the
* start of the function names. We simply put a '*' to
* accommodate them.
*/
func_name = "*" __stringify(DYN_FTRACE_TEST_NAME);
/* filter only on our function */
ftrace_set_global_filter(func_name, strlen(func_name), 1);
/* enable tracing */
ret = tracer_init(trace, tr);
if (ret) {
warn_failed_init_tracer(trace, ret);
goto out;
}
/* Sleep for a 1/10 of a second */
msleep(100);
/* we should have nothing in the buffer */
ret = trace_test_buffer(&tr->array_buffer, &count);
if (ret)
goto out;
if (count) {
ret = -1;
printk(KERN_CONT ".. filter did not filter .. ");
goto out;
}
/* call our function again */
func();
/* sleep again */
msleep(100);
/* stop the tracing. */
tracing_stop();
ftrace_enabled = 0;
/* check the trace buffer */
ret = trace_test_buffer(&tr->array_buffer, &count);
ftrace_enabled = 1;
tracing_start();
/* we should only have one item */
if (!ret && count != 1) {
trace->reset(tr);
printk(KERN_CONT ".. filter failed count=%ld ..", count);
ret = -1;
goto out;
}
/* Test the ops with global tracing running */
ret = trace_selftest_ops(tr, 1);
trace->reset(tr);
out:
ftrace_enabled = save_ftrace_enabled;
/* Enable tracing on all functions again */
ftrace_set_global_filter(NULL, 0, 1);
/* Test the ops with global tracing off */
if (!ret)
ret = trace_selftest_ops(tr, 2);
return ret;
}
static int trace_selftest_recursion_cnt;
static void trace_selftest_test_recursion_func(unsigned long ip,
unsigned long pip,
struct ftrace_ops *op,
struct pt_regs *pt_regs)
{
/*
* This function is registered without the recursion safe flag.
* The ftrace infrastructure should provide the recursion
* protection. If not, this will crash the kernel!
*/
if (trace_selftest_recursion_cnt++ > 10)
return;
DYN_FTRACE_TEST_NAME();
}
static void trace_selftest_test_recursion_safe_func(unsigned long ip,
unsigned long pip,
struct ftrace_ops *op,
struct pt_regs *pt_regs)
{
/*
* We said we would provide our own recursion. By calling
* this function again, we should recurse back into this function
* and count again. But this only happens if the arch supports
* all of ftrace features and nothing else is using the function
* tracing utility.
*/
if (trace_selftest_recursion_cnt++)
return;
DYN_FTRACE_TEST_NAME();
}
static struct ftrace_ops test_rec_probe = {
.func = trace_selftest_test_recursion_func,
};
static struct ftrace_ops test_recsafe_probe = {
.func = trace_selftest_test_recursion_safe_func,
.flags = FTRACE_OPS_FL_RECURSION_SAFE,
};
static int
trace_selftest_function_recursion(void)
{
int save_ftrace_enabled = ftrace_enabled;
char *func_name;
int len;
int ret;
/* The previous test PASSED */
pr_cont("PASSED\n");
pr_info("Testing ftrace recursion: ");
/* enable tracing, and record the filter function */
ftrace_enabled = 1;
/* Handle PPC64 '.' name */
func_name = "*" __stringify(DYN_FTRACE_TEST_NAME);
len = strlen(func_name);
ret = ftrace_set_filter(&test_rec_probe, func_name, len, 1);
if (ret) {
pr_cont("*Could not set filter* ");
goto out;
}
ret = register_ftrace_function(&test_rec_probe);
if (ret) {
pr_cont("*could not register callback* ");
goto out;
}
DYN_FTRACE_TEST_NAME();
unregister_ftrace_function(&test_rec_probe);
ret = -1;
/*
* Recursion allows for transitions between context,
* and may call the callback twice.
*/
if (trace_selftest_recursion_cnt != 1 &&
trace_selftest_recursion_cnt != 2) {
pr_cont("*callback not called once (or twice) (%d)* ",
trace_selftest_recursion_cnt);
goto out;
}
trace_selftest_recursion_cnt = 1;
pr_cont("PASSED\n");
pr_info("Testing ftrace recursion safe: ");
ret = ftrace_set_filter(&test_recsafe_probe, func_name, len, 1);
if (ret) {
pr_cont("*Could not set filter* ");
goto out;
}
ret = register_ftrace_function(&test_recsafe_probe);
if (ret) {
pr_cont("*could not register callback* ");
goto out;
}
DYN_FTRACE_TEST_NAME();
unregister_ftrace_function(&test_recsafe_probe);
ret = -1;
if (trace_selftest_recursion_cnt != 2) {
pr_cont("*callback not called expected 2 times (%d)* ",
trace_selftest_recursion_cnt);
goto out;
}
ret = 0;
out:
ftrace_enabled = save_ftrace_enabled;
return ret;
}
#else
# define trace_selftest_startup_dynamic_tracing(trace, tr, func) ({ 0; })
# define trace_selftest_function_recursion() ({ 0; })
#endif /* CONFIG_DYNAMIC_FTRACE */
static enum {
TRACE_SELFTEST_REGS_START,
TRACE_SELFTEST_REGS_FOUND,
TRACE_SELFTEST_REGS_NOT_FOUND,
} trace_selftest_regs_stat;
static void trace_selftest_test_regs_func(unsigned long ip,
unsigned long pip,
struct ftrace_ops *op,
struct pt_regs *pt_regs)
{
if (pt_regs)
trace_selftest_regs_stat = TRACE_SELFTEST_REGS_FOUND;
else
trace_selftest_regs_stat = TRACE_SELFTEST_REGS_NOT_FOUND;
}
static struct ftrace_ops test_regs_probe = {
.func = trace_selftest_test_regs_func,
.flags = FTRACE_OPS_FL_RECURSION_SAFE | FTRACE_OPS_FL_SAVE_REGS,
};
static int
trace_selftest_function_regs(void)
{
int save_ftrace_enabled = ftrace_enabled;
char *func_name;
int len;
int ret;
int supported = 0;
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
supported = 1;
#endif
/* The previous test PASSED */
pr_cont("PASSED\n");
pr_info("Testing ftrace regs%s: ",
!supported ? "(no arch support)" : "");
/* enable tracing, and record the filter function */
ftrace_enabled = 1;
/* Handle PPC64 '.' name */
func_name = "*" __stringify(DYN_FTRACE_TEST_NAME);
len = strlen(func_name);
ret = ftrace_set_filter(&test_regs_probe, func_name, len, 1);
/*
* If DYNAMIC_FTRACE is not set, then we just trace all functions.
* This test really doesn't care.
*/
if (ret && ret != -ENODEV) {
pr_cont("*Could not set filter* ");
goto out;
}
ret = register_ftrace_function(&test_regs_probe);
/*
* Now if the arch does not support passing regs, then this should
* have failed.
*/
if (!supported) {
if (!ret) {
pr_cont("*registered save-regs without arch support* ");
goto out;
}
test_regs_probe.flags |= FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED;
ret = register_ftrace_function(&test_regs_probe);
}
if (ret) {
pr_cont("*could not register callback* ");
goto out;
}
DYN_FTRACE_TEST_NAME();
unregister_ftrace_function(&test_regs_probe);
ret = -1;
switch (trace_selftest_regs_stat) {
case TRACE_SELFTEST_REGS_START:
pr_cont("*callback never called* ");
goto out;
case TRACE_SELFTEST_REGS_FOUND:
if (supported)
break;
pr_cont("*callback received regs without arch support* ");
goto out;
case TRACE_SELFTEST_REGS_NOT_FOUND:
if (!supported)
break;
pr_cont("*callback received NULL regs* ");
goto out;
}
ret = 0;
out:
ftrace_enabled = save_ftrace_enabled;
return ret;
}
/*
* Simple verification test of ftrace function tracer.
* Enable ftrace, sleep 1/10 second, and then read the trace
* buffer to see if all is in order.
*/
__init int
trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
{
int save_ftrace_enabled = ftrace_enabled;
unsigned long count;
int ret;
#ifdef CONFIG_DYNAMIC_FTRACE
if (ftrace_filter_param) {
printk(KERN_CONT " ... kernel command line filter set: force PASS ... ");
return 0;
}
#endif
/* make sure msleep has been recorded */
msleep(1);
/* start the tracing */
ftrace_enabled = 1;
ret = tracer_init(trace, tr);
if (ret) {
warn_failed_init_tracer(trace, ret);
goto out;
}
/* Sleep for a 1/10 of a second */
msleep(100);
/* stop the tracing. */
tracing_stop();
ftrace_enabled = 0;
/* check the trace buffer */
ret = trace_test_buffer(&tr->array_buffer, &count);
ftrace_enabled = 1;
trace->reset(tr);
tracing_start();
if (!ret && !count) {
printk(KERN_CONT ".. no entries found ..");
ret = -1;
goto out;
}
ret = trace_selftest_startup_dynamic_tracing(trace, tr,
DYN_FTRACE_TEST_NAME);
if (ret)
goto out;
ret = trace_selftest_function_recursion();
if (ret)
goto out;
ret = trace_selftest_function_regs();
out:
ftrace_enabled = save_ftrace_enabled;
/* kill ftrace totally if we failed */
if (ret)
ftrace_kill();
return ret;
}
#endif /* CONFIG_FUNCTION_TRACER */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/* Maximum number of functions to trace before diagnosing a hang */
#define GRAPH_MAX_FUNC_TEST 100000000
static unsigned int graph_hang_thresh;
/* Wrap the real function entry probe to avoid possible hanging */
static int trace_graph_entry_watchdog(struct ftrace_graph_ent *trace)
{
/* This is harmlessly racy, we want to approximately detect a hang */
if (unlikely(++graph_hang_thresh > GRAPH_MAX_FUNC_TEST)) {
ftrace_graph_stop();
printk(KERN_WARNING "BUG: Function graph tracer hang!\n");
if (ftrace_dump_on_oops) {
ftrace_dump(DUMP_ALL);
/* ftrace_dump() disables tracing */
tracing_on();
}
return 0;
}
return trace_graph_entry(trace);
}
static struct fgraph_ops fgraph_ops __initdata = {
.entryfunc = &trace_graph_entry_watchdog,
.retfunc = &trace_graph_return,
};
/*
* Pretty much the same than for the function tracer from which the selftest
* has been borrowed.
*/
__init int
trace_selftest_startup_function_graph(struct tracer *trace,
struct trace_array *tr)
{
int ret;
unsigned long count;
#ifdef CONFIG_DYNAMIC_FTRACE
if (ftrace_filter_param) {
printk(KERN_CONT " ... kernel command line filter set: force PASS ... ");
return 0;
}
#endif
/*
* Simulate the init() callback but we attach a watchdog callback
* to detect and recover from possible hangs
*/
tracing_reset_online_cpus(&tr->array_buffer);
set_graph_array(tr);
ret = register_ftrace_graph(&fgraph_ops);
if (ret) {
warn_failed_init_tracer(trace, ret);
goto out;
}
tracing_start_cmdline_record();
/* Sleep for a 1/10 of a second */
msleep(100);
/* Have we just recovered from a hang? */
if (graph_hang_thresh > GRAPH_MAX_FUNC_TEST) {
tracing_selftest_disabled = true;
ret = -1;
goto out;
}
tracing_stop();
/* check the trace buffer */
ret = trace_test_buffer(&tr->array_buffer, &count);
/* Need to also simulate the tr->reset to remove this fgraph_ops */
tracing_stop_cmdline_record();
unregister_ftrace_graph(&fgraph_ops);
tracing_start();
if (!ret && !count) {
printk(KERN_CONT ".. no entries found ..");
ret = -1;
goto out;
}
/* Don't test dynamic tracing, the function tracer already did */
out:
/* Stop it if we failed */
if (ret)
ftrace_graph_stop();
return ret;
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
#ifdef CONFIG_IRQSOFF_TRACER
int
trace_selftest_startup_irqsoff(struct tracer *trace, struct trace_array *tr)
{
unsigned long save_max = tr->max_latency;
unsigned long count;
int ret;
/* start the tracing */
ret = tracer_init(trace, tr);
if (ret) {
warn_failed_init_tracer(trace, ret);
return ret;
}
/* reset the max latency */
tr->max_latency = 0;
/* disable interrupts for a bit */
local_irq_disable();
udelay(100);
local_irq_enable();
/*
* Stop the tracer to avoid a warning subsequent
* to buffer flipping failure because tracing_stop()
* disables the tr and max buffers, making flipping impossible
* in case of parallels max irqs off latencies.
*/
trace->stop(tr);
/* stop the tracing. */
tracing_stop();
/* check both trace buffers */
ret = trace_test_buffer(&tr->array_buffer, NULL);
if (!ret)
ret = trace_test_buffer(&tr->max_buffer, &count);
trace->reset(tr);
tracing_start();
if (!ret && !count) {
printk(KERN_CONT ".. no entries found ..");
ret = -1;
}
tr->max_latency = save_max;
return ret;
}
#endif /* CONFIG_IRQSOFF_TRACER */
#ifdef CONFIG_PREEMPT_TRACER
int
trace_selftest_startup_preemptoff(struct tracer *trace, struct trace_array *tr)
{
unsigned long save_max = tr->max_latency;
unsigned long count;
int ret;
/*
* Now that the big kernel lock is no longer preemptable,
* and this is called with the BKL held, it will always
* fail. If preemption is already disabled, simply
* pass the test. When the BKL is removed, or becomes
* preemptible again, we will once again test this,
* so keep it in.
*/
if (preempt_count()) {
printk(KERN_CONT "can not test ... force ");
return 0;
}
/* start the tracing */
ret = tracer_init(trace, tr);
if (ret) {
warn_failed_init_tracer(trace, ret);
return ret;
}
/* reset the max latency */
tr->max_latency = 0;
/* disable preemption for a bit */
preempt_disable();
udelay(100);
preempt_enable();
/*
* Stop the tracer to avoid a warning subsequent
* to buffer flipping failure because tracing_stop()
* disables the tr and max buffers, making flipping impossible
* in case of parallels max preempt off latencies.
*/
trace->stop(tr);
/* stop the tracing. */
tracing_stop();
/* check both trace buffers */
ret = trace_test_buffer(&tr->array_buffer, NULL);
if (!ret)
ret = trace_test_buffer(&tr->max_buffer, &count);
trace->reset(tr);
tracing_start();
if (!ret && !count) {
printk(KERN_CONT ".. no entries found ..");
ret = -1;
}
tr->max_latency = save_max;
return ret;
}
#endif /* CONFIG_PREEMPT_TRACER */
#if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
int
trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *tr)
{
unsigned long save_max = tr->max_latency;
unsigned long count;
int ret;
/*
* Now that the big kernel lock is no longer preemptable,
* and this is called with the BKL held, it will always
* fail. If preemption is already disabled, simply
* pass the test. When the BKL is removed, or becomes
* preemptible again, we will once again test this,
* so keep it in.
*/
if (preempt_count()) {
printk(KERN_CONT "can not test ... force ");
return 0;
}
/* start the tracing */
ret = tracer_init(trace, tr);
if (ret) {
warn_failed_init_tracer(trace, ret);
goto out_no_start;
}
/* reset the max latency */
tr->max_latency = 0;
/* disable preemption and interrupts for a bit */
preempt_disable();
local_irq_disable();
udelay(100);
preempt_enable();
/* reverse the order of preempt vs irqs */
local_irq_enable();
/*
* Stop the tracer to avoid a warning subsequent
* to buffer flipping failure because tracing_stop()
* disables the tr and max buffers, making flipping impossible
* in case of parallels max irqs/preempt off latencies.
*/
trace->stop(tr);
/* stop the tracing. */
tracing_stop();
/* check both trace buffers */
ret = trace_test_buffer(&tr->array_buffer, NULL);
if (ret)
goto out;
ret = trace_test_buffer(&tr->max_buffer, &count);
if (ret)
goto out;
if (!ret && !count) {
printk(KERN_CONT ".. no entries found ..");
ret = -1;
goto out;
}
/* do the test by disabling interrupts first this time */
tr->max_latency = 0;
tracing_start();
trace->start(tr);
preempt_disable();
local_irq_disable();
udelay(100);
preempt_enable();
/* reverse the order of preempt vs irqs */
local_irq_enable();
trace->stop(tr);
/* stop the tracing. */
tracing_stop();
/* check both trace buffers */
ret = trace_test_buffer(&tr->array_buffer, NULL);
if (ret)
goto out;
ret = trace_test_buffer(&tr->max_buffer, &count);
if (!ret && !count) {
printk(KERN_CONT ".. no entries found ..");
ret = -1;
goto out;
}
out:
tracing_start();
out_no_start:
trace->reset(tr);
tr->max_latency = save_max;
return ret;
}
#endif /* CONFIG_IRQSOFF_TRACER && CONFIG_PREEMPT_TRACER */
#ifdef CONFIG_NOP_TRACER
int
trace_selftest_startup_nop(struct tracer *trace, struct trace_array *tr)
{
/* What could possibly go wrong? */
return 0;
}
#endif
#ifdef CONFIG_SCHED_TRACER
struct wakeup_test_data {
struct completion is_ready;
int go;
};
static int trace_wakeup_test_thread(void *data)
{
/* Make this a -deadline thread */
static const struct sched_attr attr = {
.sched_policy = SCHED_DEADLINE,
.sched_runtime = 100000ULL,
.sched_deadline = 10000000ULL,
.sched_period = 10000000ULL
};
struct wakeup_test_data *x = data;
sched_setattr(current, &attr);
/* Make it know we have a new prio */
complete(&x->is_ready);
/* now go to sleep and let the test wake us up */
set_current_state(TASK_INTERRUPTIBLE);
while (!x->go) {
schedule();
set_current_state(TASK_INTERRUPTIBLE);
}
complete(&x->is_ready);
set_current_state(TASK_INTERRUPTIBLE);
/* we are awake, now wait to disappear */
while (!kthread_should_stop()) {
schedule();
set_current_state(TASK_INTERRUPTIBLE);
}
__set_current_state(TASK_RUNNING);
return 0;
}
int
trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
{
unsigned long save_max = tr->max_latency;
struct task_struct *p;
struct wakeup_test_data data;
unsigned long count;
int ret;
memset(&data, 0, sizeof(data));
init_completion(&data.is_ready);
/* create a -deadline thread */
p = kthread_run(trace_wakeup_test_thread, &data, "ftrace-test");
if (IS_ERR(p)) {
printk(KERN_CONT "Failed to create ftrace wakeup test thread ");
return -1;
}
/* make sure the thread is running at -deadline policy */
wait_for_completion(&data.is_ready);
/* start the tracing */
ret = tracer_init(trace, tr);
if (ret) {
warn_failed_init_tracer(trace, ret);
return ret;
}
/* reset the max latency */
tr->max_latency = 0;
while (p->on_rq) {
/*
* Sleep to make sure the -deadline thread is asleep too.
* On virtual machines we can't rely on timings,
* but we want to make sure this test still works.
*/
msleep(100);
}
init_completion(&data.is_ready);
data.go = 1;
/* memory barrier is in the wake_up_process() */
wake_up_process(p);
/* Wait for the task to wake up */
wait_for_completion(&data.is_ready);
/* stop the tracing. */
tracing_stop();
/* check both trace buffers */
ret = trace_test_buffer(&tr->array_buffer, NULL);
if (!ret)
ret = trace_test_buffer(&tr->max_buffer, &count);
trace->reset(tr);
tracing_start();
tr->max_latency = save_max;
/* kill the thread */
kthread_stop(p);
if (!ret && !count) {
printk(KERN_CONT ".. no entries found ..");
ret = -1;
}
return ret;
}
#endif /* CONFIG_SCHED_TRACER */
#ifdef CONFIG_BRANCH_TRACER
int
trace_selftest_startup_branch(struct tracer *trace, struct trace_array *tr)
{
unsigned long count;
int ret;
/* start the tracing */
ret = tracer_init(trace, tr);
if (ret) {
warn_failed_init_tracer(trace, ret);
return ret;
}
/* Sleep for a 1/10 of a second */
msleep(100);
/* stop the tracing. */
tracing_stop();
/* check the trace buffer */
ret = trace_test_buffer(&tr->array_buffer, &count);
trace->reset(tr);
tracing_start();
if (!ret && !count) {
printk(KERN_CONT ".. no entries found ..");
ret = -1;
}
return ret;
}
#endif /* CONFIG_BRANCH_TRACER */