Support multi-buffer on uprobe-based dynamic events by
using ftrace_event_file.
This patch is based kprobe-based dynamic events multibuffer
support work initially, commited by Masami(commit 41a7dd420c),
but revised as below:
Oleg changed the kprobe-based multibuffer design from
array-pointers of ftrace_event_file into simple list,
so this patch also change to the list degisn.
rcu_read_lock/unlock added into uprobe_trace_func/uretprobe_trace_func,
to synchronize with ftrace_event_file list add and delete.
Even though we allow multi-uprobes instances now,
but TP_FLAG_PROFILE/TP_FLAG_TRACE are still mutually exclusive
in probe_event_enable currently, this means we cannot allow
one user is using uprobe-tracer, and another user is using
perf-probe on same uprobe concurrently.
(Perhaps this will be fix in future, kprobe dont't have this
limitation now)
Signed-off-by: zhangwei(Jovi) <jovi.zhang...@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu...@hitachi.com>
Cc: Frederic Weisbecker <fweis...@gmail.com>
Cc: Oleg Nesterov <o...@redhat.com>
Cc: Srikar Dronamraju <sri...@linux.vnet.ibm.com>
---
kernel/trace/trace_uprobe.c | 118 +++++++++++++++++++++++++++++++++++--------
1 file changed, 97 insertions(+), 21 deletions(-)
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 32494fb0..dbbb4a9 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -53,6 +53,7 @@ struct trace_uprobe {
struct list_head list;
struct ftrace_event_class class;
struct ftrace_event_call call;
+ struct list_head files;
struct trace_uprobe_filter filter;
struct uprobe_consumer consumer;
struct inode *inode;
@@ -65,6 +66,11 @@ struct trace_uprobe {
struct probe_arg args[];
};
+struct event_file_link {
+ struct ftrace_event_file *file;
+ struct list_head list;
+};
+
#define SIZEOF_TRACE_UPROBE(n) \
(offsetof(struct trace_uprobe, args) + \
(sizeof(struct probe_arg) * (n)))
@@ -124,6 +130,7 @@ alloc_trace_uprobe(const char *group, const char *event,
int nargs, bool is_ret)
goto error;
INIT_LIST_HEAD(&tu->list);
+ INIT_LIST_HEAD(&tu->files);
tu->consumer.handler = uprobe_dispatcher;
if (is_ret)
tu->consumer.ret_handler = uretprobe_dispatcher;
@@ -511,7 +518,8 @@ static const struct file_operations uprobe_profile_ops = {
};
static void uprobe_trace_print(struct trace_uprobe *tu,
- unsigned long func, struct pt_regs *regs)
+ unsigned long func, struct pt_regs *regs,
+ struct ftrace_event_file *ftrace_file)
{
struct uprobe_trace_entry_head *entry;
struct ring_buffer_event *event;
@@ -520,9 +528,12 @@ static void uprobe_trace_print(struct trace_uprobe *tu,
int size, i;
struct ftrace_event_call *call = &tu->call;
+ WARN_ON(call != ftrace_file->event_call);
+
size = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
- event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
- size + tu->size, 0, 0);
+ event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
+ call->event.type,
+ size + tu->size, 0, 0);
if (!event)
return;
@@ -546,15 +557,28 @@ static void uprobe_trace_print(struct trace_uprobe *tu,
/* uprobe handler */
static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
{
- if (!is_ret_probe(tu))
- uprobe_trace_print(tu, 0, regs);
+ struct event_file_link *link;
+
+ if (is_ret_probe(tu))
+ return 0;
+
+ rcu_read_lock();
+ list_for_each_entry(link, &tu->files, list)
+ uprobe_trace_print(tu, 0, regs, link->file);
+ rcu_read_unlock();
+
return 0;
}
static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
struct pt_regs *regs)
{
- uprobe_trace_print(tu, func, regs);
+ struct event_file_link *link;
+
+ rcu_read_lock();
+ list_for_each_entry(link, &tu->files, list)
+ uprobe_trace_print(tu, func, regs, link->file);
+ rcu_read_unlock();
}
/* Event entry printers */
@@ -605,33 +629,84 @@ typedef bool (*filter_func_t)(struct uprobe_consumer
*self,
struct mm_struct *mm);
static int
-probe_event_enable(struct trace_uprobe *tu, int flag, filter_func_t filter)
+probe_event_enable(struct trace_uprobe *tu, struct ftrace_event_file *file,
+ filter_func_t filter)
{
+ int enabled = 0;
int ret = 0;
+ /* we cannot call uprobe_register twice for same tu */
if (is_trace_uprobe_enabled(tu))
- return -EINTR;
+ enabled = 1;
+
+ if (file) {
+ struct event_file_link *link;
+
+ if (tu->flags & TP_FLAG_PROFILE)
+ return -EINTR;
+
+ link = kmalloc(sizeof(*link), GFP_KERNEL);
+ if (!link)
+ return -ENOMEM;
+
+ link->file = file;
+ list_add_rcu(&link->list, &tu->files);
+
+ tu->flags |= TP_FLAG_TRACE;
+ } else {
+ if (tu->flags & TP_FLAG_TRACE)
+ return -EINTR;
+
+ tu->flags |= TP_FLAG_PROFILE;
+ }
WARN_ON(!uprobe_filter_is_empty(&tu->filter));
- tu->flags |= flag;
- tu->consumer.filter = filter;
- ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
- if (ret)
- tu->flags &= ~flag;
+ if (!enabled) {
+ tu->consumer.filter = filter;
+ ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
+ if (ret)
+ tu->flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;
+ }
return ret;
}
-static void probe_event_disable(struct trace_uprobe *tu, int flag)
+static struct event_file_link *
+find_event_file_link(struct trace_uprobe *tu, struct ftrace_event_file *file)
{
- if (!is_trace_uprobe_enabled(tu))
- return;
+ struct event_file_link *link;
+
+ list_for_each_entry(link, &tu->files, list)
+ if (link->file == file)
+ return link;
+
+ return NULL;
+}
+
+static void
+probe_event_disable(struct trace_uprobe *tu, struct ftrace_event_file *file)
+{
+ if (file) {
+ struct event_file_link *link;
+
+ link = find_event_file_link(tu, file);
+ if (!link)
+ return;
+
+ list_del_rcu(&link->list);
+ /* synchronize with uprobe_trace_func/uretprobe_trace_func */
+ synchronize_sched();
+ kfree(link);
+
+ if (!list_empty(&tu->files))
+ return;
+ }
WARN_ON(!uprobe_filter_is_empty(&tu->filter));
uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
- tu->flags &= ~flag;
+ tu->flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;
}
static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
@@ -867,21 +942,22 @@ static
int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg
type, void *data)
{
struct trace_uprobe *tu = event->data;
+ struct ftrace_event_file *file = data;
switch (type) {
case TRACE_REG_REGISTER:
- return probe_event_enable(tu, TP_FLAG_TRACE, NULL);
+ return probe_event_enable(tu, file, NULL);
case TRACE_REG_UNREGISTER:
- probe_event_disable(tu, TP_FLAG_TRACE);
+ probe_event_disable(tu, file);
return 0;
#ifdef CONFIG_PERF_EVENTS
case TRACE_REG_PERF_REGISTER:
- return probe_event_enable(tu, TP_FLAG_PROFILE,
uprobe_perf_filter);
+ return probe_event_enable(tu, NULL, uprobe_perf_filter);
case TRACE_REG_PERF_UNREGISTER:
- probe_event_disable(tu, TP_FLAG_PROFILE);
+ probe_event_disable(tu, NULL);
return 0;
case TRACE_REG_PERF_OPEN:
--
1.7.9.7
--
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