[PATCH 17/18] tracing/kprobes: Support ftrace_event_file base multibuffer

Steven Rostedt
2013-05-11T00:13:42Z

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From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

Support multi-buffer on kprobe-based dynamic events by
using ftrace_event_file.

Link: http://lkml.kernel.org/r/20130509054449.30398.88343.stgit@mhiramat-M0-7522

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Tom Zanussi <tom.zanussi@intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace_kprobe.c | 250 ++++++++++++++++++++++++++++++++++++-------
1 file changed, 214 insertions(+), 36 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 9ca44fc..fee865d 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -27,7 +27,6 @@
/**
* Kprobe event core functions
*/
-
struct trace_probe {
struct list_head list;
struct kretprobe rp; /* Use rp.kp for kprobe use */
@@ -36,6 +35,7 @@ struct trace_probe {
const char *symbol; /* symbol name */
struct ftrace_event_class class;
struct ftrace_event_call call;
+ struct ftrace_event_file **files;
ssize_t size; /* trace entry size */
unsigned int nr_args;
struct probe_arg args[];
@@ -183,12 +183,57 @@ static struct trace_probe *find_trace_probe(const char *event,
return NULL;
}

-/* Enable trace_probe - @flag must be TP_FLAG_TRACE or TP_FLAG_PROFILE */
-static int enable_trace_probe(struct trace_probe *tp, int flag)
+static int trace_probe_nr_files(struct trace_probe *tp)
+{
+ struct ftrace_event_file **file = tp->files;
+ int ret = 0;
+
+ if (file)
+ while (*(file++))
+ ret++;
+
+ return ret;
+}
+
+static DEFINE_MUTEX(probe_enable_lock);
+
+/*
+ * Enable trace_probe
+ * if the file is NULL, enable "perf" handler, or enable "trace" handler.
+ */
+static int
+enable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
{
int ret = 0;

- tp->flags |= flag;
+ mutex_lock(&probe_enable_lock);
+
+ if (file) {
+ struct ftrace_event_file **new, **old = tp->files;
+ int n = trace_probe_nr_files(tp);
+
+ /* 1 is for new one and 1 is for stopper */
+ new = kzalloc((n + 2) * sizeof(struct ftrace_event_file *),
+ GFP_KERNEL);
+ if (!new) {
+ ret = -ENOMEM;
+ goto out_unlock;
+ }
+ memcpy(new, old, n * sizeof(struct ftrace_event_file *));
+ new[n] = file;
+ /* The last one keeps a NULL */
+
+ rcu_assign_pointer(tp->files, new);
+ tp->flags |= TP_FLAG_TRACE;
+
+ if (old) {
+ /* Make sure the probe is done with old files */
+ synchronize_sched();
+ kfree(old);
+ }
+ } else
+ tp->flags |= TP_FLAG_PROFILE;
+
if (trace_probe_is_enabled(tp) && trace_probe_is_registered(tp) &&
!trace_probe_has_gone(tp)) {
if (trace_probe_is_return(tp))
@@ -197,19 +242,83 @@ static int enable_trace_probe(struct trace_probe *tp, int flag)
ret = enable_kprobe(&tp->rp.kp);
}

+ out_unlock:
+ mutex_unlock(&probe_enable_lock);
+
return ret;
}

-/* Disable trace_probe - @flag must be TP_FLAG_TRACE or TP_FLAG_PROFILE */
-static void disable_trace_probe(struct trace_probe *tp, int flag)
+static int
+trace_probe_file_index(struct trace_probe *tp, struct ftrace_event_file *file)
+{
+ int i;
+
+ if (tp->files) {
+ for (i = 0; tp->files[i]; i++)
+ if (tp->files[i] == file)
+ return i;
+ }
+
+ return -1;
+}
+
+/*
+ * Disable trace_probe
+ * if the file is NULL, disable "perf" handler, or disable "trace" handler.
+ */
+static int
+disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
{
- tp->flags &= ~flag;
+ int ret = 0;
+
+ mutex_lock(&probe_enable_lock);
+
+ if (file) {
+ struct ftrace_event_file **new, **old = tp->files;
+ int n = trace_probe_nr_files(tp);
+ int i, j;
+
+ if (n == 0 || trace_probe_file_index(tp, file) < 0) {
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ if (n == 1) { /* Remove the last file */
+ tp->flags &= ~TP_FLAG_TRACE;
+ new = NULL;
+ } else {
+ new = kzalloc(n * sizeof(struct ftrace_event_file *),
+ GFP_KERNEL);
+ if (!new) {
+ ret = -ENOMEM;
+ goto out_unlock;
+ }
+
+ /* This copy & check loop copies the NULL stopper too */
+ for (i = 0, j = 0; j < n && i < n + 1; i++)
+ if (old[i] != file)
+ new[j++] = old[i];
+ }
+
+ rcu_assign_pointer(tp->files, new);
+
+ /* Make sure the probe is done with old files */
+ synchronize_sched();
+ kfree(old);
+ } else
+ tp->flags &= ~TP_FLAG_PROFILE;
+
if (!trace_probe_is_enabled(tp) && trace_probe_is_registered(tp)) {
if (trace_probe_is_return(tp))
disable_kretprobe(&tp->rp);
else
disable_kprobe(&tp->rp.kp);
}
+
+ out_unlock:
+ mutex_unlock(&probe_enable_lock);
+
+ return ret;
}

/* Internal register function - just handle k*probes and flags */
@@ -724,7 +833,8 @@ static __kprobes void store_trace_args(int ent_size, struct trace_probe *tp,

/* Kprobe handler */
static __kprobes void
-kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs)
+__kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs,
+ struct ftrace_event_file *ftrace_file)
{
struct kprobe_trace_entry_head *entry;
struct ring_buffer_event *event;
@@ -733,14 +843,17 @@ kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs)
unsigned long irq_flags;
struct ftrace_event_call *call = &tp->call;

+ WARN_ON(call != ftrace_file->event_call);
+
local_save_flags(irq_flags);
pc = preempt_count();

dsize = __get_data_size(tp, regs);
size = sizeof(*entry) + tp->size + dsize;

- event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
- size, irq_flags, pc);
+ event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
+ call->event.type,
+ size, irq_flags, pc);
if (!event)
return;

@@ -753,10 +866,23 @@ kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs)
irq_flags, pc, regs);
}

+static __kprobes void
+kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs)
+{
+ struct ftrace_event_file **file = tp->files;
+
+ /* Note: preempt is already disabled around the kprobe handler */
+ while (*file) {
+ __kprobe_trace_func(tp, regs, *file);
+ file++;
+ }
+}
+
/* Kretprobe handler */
static __kprobes void
-kretprobe_trace_func(struct trace_probe *tp, struct kretprobe_instance *ri,
- struct pt_regs *regs)
+__kretprobe_trace_func(struct trace_probe *tp, struct kretprobe_instance *ri,
+ struct pt_regs *regs,
+ struct ftrace_event_file *ftrace_file)
{
struct kretprobe_trace_entry_head *entry;
struct ring_buffer_event *event;
@@ -765,14 +891,17 @@ kretprobe_trace_func(struct trace_probe *tp, struct kretprobe_instance *ri,
unsigned long irq_flags;
struct ftrace_event_call *call = &tp->call;

+ WARN_ON(call != ftrace_file->event_call);
+
local_save_flags(irq_flags);
pc = preempt_count();

dsize = __get_data_size(tp, regs);
size = sizeof(*entry) + tp->size + dsize;

- event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
- size, irq_flags, pc);
+ event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
+ call->event.type,
+ size, irq_flags, pc);
if (!event)
return;

@@ -786,6 +915,19 @@ kretprobe_trace_func(struct trace_probe *tp, struct kretprobe_instance *ri,
irq_flags, pc, regs);
}

+static __kprobes void
+kretprobe_trace_func(struct trace_probe *tp, struct kretprobe_instance *ri,
+ struct pt_regs *regs)
+{
+ struct ftrace_event_file **file = tp->files;
+
+ /* Note: preempt is already disabled around the kprobe handler */
+ while (*file) {
+ __kretprobe_trace_func(tp, ri, regs, *file);
+ file++;
+ }
+}
+
/* Event entry printers */
enum print_line_t
print_kprobe_event(struct trace_iterator *iter, int flags,
@@ -1041,20 +1183,19 @@ int kprobe_register(struct ftrace_event_call *event,
enum trace_reg type, void *data)
{
struct trace_probe *tp = (struct trace_probe *)event->data;
+ struct ftrace_event_file *file = data;

switch (type) {
case TRACE_REG_REGISTER:
- return enable_trace_probe(tp, TP_FLAG_TRACE);
+ return enable_trace_probe(tp, file);
case TRACE_REG_UNREGISTER:
- disable_trace_probe(tp, TP_FLAG_TRACE);
- return 0;
+ return disable_trace_probe(tp, file);

#ifdef CONFIG_PERF_EVENTS
case TRACE_REG_PERF_REGISTER:
- return enable_trace_probe(tp, TP_FLAG_PROFILE);
+ return enable_trace_probe(tp, NULL);
case TRACE_REG_PERF_UNREGISTER:
- disable_trace_probe(tp, TP_FLAG_PROFILE);
- return 0;
+ return disable_trace_probe(tp, NULL);
case TRACE_REG_PERF_OPEN:
case TRACE_REG_PERF_CLOSE:
case TRACE_REG_PERF_ADD:
@@ -1190,11 +1331,24 @@ static __used int kprobe_trace_selftest_target(int a1, int a2, int a3,
return a1 + a2 + a3 + a4 + a5 + a6;
}

+static struct ftrace_event_file *
+find_trace_probe_file(struct trace_probe *tp, struct trace_array *tr)
+{
+ struct ftrace_event_file *file;
+
+ list_for_each_entry(file, &tr->events, list)
+ if (file->event_call == &tp->call)
+ return file;
+
+ return NULL;
+}
+
static __init int kprobe_trace_self_tests_init(void)
{
int ret, warn = 0;
int (*target)(int, int, int, int, int, int);
struct trace_probe *tp;
+ struct ftrace_event_file *file;

target = kprobe_trace_selftest_target;

@@ -1204,31 +1358,43 @@ static __init int kprobe_trace_self_tests_init(void)
"$stack $stack0 +0($stack)",
create_trace_probe);
if (WARN_ON_ONCE(ret)) {
- pr_warning("error on probing function entry.\n");
+ pr_warn("error on probing function entry.\n");
warn++;
} else {
/* Enable trace point */
tp = find_trace_probe("testprobe", KPROBE_EVENT_SYSTEM);
if (WARN_ON_ONCE(tp == NULL)) {
- pr_warning("error on getting new probe.\n");
+ pr_warn("error on getting new probe.\n");
warn++;
- } else
- enable_trace_probe(tp, TP_FLAG_TRACE);
+ } else {
+ file = find_trace_probe_file(tp, top_trace_array());
+ if (WARN_ON_ONCE(file == NULL)) {
+ pr_warn("error on getting probe file.\n");
+ warn++;
+ } else
+ enable_trace_probe(tp, file);
+ }
}

ret = traceprobe_command("r:testprobe2 kprobe_trace_selftest_target "
"$retval", create_trace_probe);
if (WARN_ON_ONCE(ret)) {
- pr_warning("error on probing function return.\n");
+ pr_warn("error on probing function return.\n");
warn++;
} else {
/* Enable trace point */
tp = find_trace_probe("testprobe2", KPROBE_EVENT_SYSTEM);
if (WARN_ON_ONCE(tp == NULL)) {
- pr_warning("error on getting new probe.\n");
+ pr_warn("error on getting 2nd new probe.\n");
warn++;
- } else
- enable_trace_probe(tp, TP_FLAG_TRACE);
+ } else {
+ file = find_trace_probe_file(tp, top_trace_array());
+ if (WARN_ON_ONCE(file == NULL)) {
+ pr_warn("error on getting probe file.\n");
+ warn++;
+ } else
+ enable_trace_probe(tp, file);
+ }
}

if (warn)
@@ -1239,27 +1405,39 @@ static __init int kprobe_trace_self_tests_init(void)
/* Disable trace points before removing it */
tp = find_trace_probe("testprobe", KPROBE_EVENT_SYSTEM);
if (WARN_ON_ONCE(tp == NULL)) {
- pr_warning("error on getting test probe.\n");
+ pr_warn("error on getting test probe.\n");
warn++;
- } else
- disable_trace_probe(tp, TP_FLAG_TRACE);
+ } else {
+ file = find_trace_probe_file(tp, top_trace_array());
+ if (WARN_ON_ONCE(file == NULL)) {
+ pr_warn("error on getting probe file.\n");
+ warn++;
+ } else
+ disable_trace_probe(tp, file);
+ }

tp = find_trace_probe("testprobe2", KPROBE_EVENT_SYSTEM);
if (WARN_ON_ONCE(tp == NULL)) {
- pr_warning("error on getting 2nd test probe.\n");
+ pr_warn("error on getting 2nd test probe.\n");
warn++;
- } else
- disable_trace_probe(tp, TP_FLAG_TRACE);
+ } else {
+ file = find_trace_probe_file(tp, top_trace_array());
+ if (WARN_ON_ONCE(file == NULL)) {
+ pr_warn("error on getting probe file.\n");
+ warn++;
+ } else
+ disable_trace_probe(tp, file);
+ }

ret = traceprobe_command("-:testprobe", create_trace_probe);
if (WARN_ON_ONCE(ret)) {
- pr_warning("error on deleting a probe.\n");
+ pr_warn("error on deleting a probe.\n");
warn++;
}

ret = traceprobe_command("-:testprobe2", create_trace_probe);
if (WARN_ON_ONCE(ret)) {
- pr_warning("error on deleting a probe.\n");
+ pr_warn("error on deleting a probe.\n");
warn++;
}