tracing/uprobes: Support ftrace_event_file base multibuffer

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 design.

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 don't have this
limitation now)

Link: http://lkml.kernel.org/r/1389946120-19610-4-git-send-email-namhyung@kernel.org
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index bdbae45..d021d21 100644 (file)
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -35,11 +35,6 @@ struct trace_kprobe {
        struct trace_probe      tp;
 };
 
-struct event_file_link {
-       struct ftrace_event_file        *file;
-       struct list_head                list;
-};
-
 #define SIZEOF_TRACE_KPROBE(n)                         \
        (offsetof(struct trace_kprobe, tp.args) +       \
        (sizeof(struct probe_arg) * (n)))
@@ -387,18 +382,6 @@ enable_trace_kprobe(struct trace_kprobe *tk, struct ftrace_event_file *file)
        return ret;
 }
 
-static struct event_file_link *
-find_event_file_link(struct trace_probe *tp, struct ftrace_event_file *file)
-{
-       struct event_file_link *link;
-
-       list_for_each_entry(link, &tp->files, list)
-               if (link->file == file)
-                       return link;
-
-       return NULL;
-}
-
 /*
  * Disable trace_probe
  * if the file is NULL, disable "perf" handler, or disable "trace" handler.

diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index b73574a..fb1ab5d 100644 (file)
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -288,6 +288,11 @@ struct trace_probe {
        struct probe_arg                args[];
 };
 
+struct event_file_link {
+       struct ftrace_event_file        *file;
+       struct list_head                list;
+};
+
 static inline bool trace_probe_is_enabled(struct trace_probe *tp)
 {
        return !!(tp->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE));
@@ -316,6 +321,18 @@ static inline int is_good_name(const char *name)
        return 1;
 }
 
+static inline struct event_file_link *
+find_event_file_link(struct trace_probe *tp, struct ftrace_event_file *file)
+{
+       struct event_file_link *link;
+
+       list_for_each_entry(link, &tp->files, list)
+               if (link->file == file)
+                       return link;
+
+       return NULL;
+}
+
 extern int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
                   struct probe_arg *parg, bool is_return, bool is_kprobe);
 

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index d83155e..349c6df 100644 (file)
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -260,6 +260,7 @@ 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->tp.files);
        tu->consumer.handler = uprobe_dispatcher;
        if (is_ret)
                tu->consumer.ret_handler = uretprobe_dispatcher;
@@ -760,7 +761,8 @@ static void uprobe_buffer_put(struct uprobe_cpu_buffer *ucb)
 
 static void __uprobe_trace_func(struct trace_uprobe *tu,
                                unsigned long func, struct pt_regs *regs,
-                               struct uprobe_cpu_buffer *ucb, int dsize)
+                               struct uprobe_cpu_buffer *ucb, int dsize,
+                               struct ftrace_event_file *ftrace_file)
 {
        struct uprobe_trace_entry_head *entry;
        struct ring_buffer_event *event;
@@ -769,13 +771,15 @@ static void __uprobe_trace_func(struct trace_uprobe *tu,
        int size, esize;
        struct ftrace_event_call *call = &tu->tp.call;
 
+       WARN_ON(call != ftrace_file->event_call);
+
        if (WARN_ON_ONCE(tu->tp.size + dsize > PAGE_SIZE))
                return;
 
        esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
        size = esize + tu->tp.size + dsize;
-       event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
-                                                 size, 0, 0);
+       event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
+                                               call->event.type, size, 0, 0);
        if (!event)
                return;
 
@@ -799,8 +803,16 @@ static void __uprobe_trace_func(struct trace_uprobe *tu,
 static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs,
                             struct uprobe_cpu_buffer *ucb, int dsize)
 {
-       if (!is_ret_probe(tu))
-               __uprobe_trace_func(tu, 0, regs, ucb, dsize);
+       struct event_file_link *link;
+
+       if (is_ret_probe(tu))
+               return 0;
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(link, &tu->tp.files, list)
+               __uprobe_trace_func(tu, 0, regs, ucb, dsize, link->file);
+       rcu_read_unlock();
+
        return 0;
 }
 
@@ -808,7 +820,12 @@ static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
                                 struct pt_regs *regs,
                                 struct uprobe_cpu_buffer *ucb, int dsize)
 {
-       __uprobe_trace_func(tu, func, regs, ucb, dsize);
+       struct event_file_link *link;
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(link, &tu->tp.files, list)
+               __uprobe_trace_func(tu, func, regs, ucb, dsize, link->file);
+       rcu_read_unlock();
 }
 
 /* Event entry printers */
@@ -855,12 +872,31 @@ 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 ret = 0;
+       bool enabled = trace_probe_is_enabled(&tu->tp);
+       struct event_file_link *link = NULL;
+       int ret;
+
+       if (file) {
+               if (tu->tp.flags & TP_FLAG_PROFILE)
+                       return -EINTR;
 
-       if (trace_probe_is_enabled(&tu->tp))
-               return -EINTR;
+               link = kmalloc(sizeof(*link), GFP_KERNEL);
+               if (!link)
+                       return -ENOMEM;
+
+               link->file = file;
+               list_add_tail_rcu(&link->list, &tu->tp.files);
+
+               tu->tp.flags |= TP_FLAG_TRACE;
+       } else {
+               if (tu->tp.flags & TP_FLAG_TRACE)
+                       return -EINTR;
+
+               tu->tp.flags |= TP_FLAG_PROFILE;
+       }
 
        ret = uprobe_buffer_enable();
        if (ret < 0)
@@ -868,24 +904,49 @@ probe_event_enable(struct trace_uprobe *tu, int flag, filter_func_t filter)
 
        WARN_ON(!uprobe_filter_is_empty(&tu->filter));
 
-       tu->tp.flags |= flag;
+       if (enabled)
+               return 0;
+
        tu->consumer.filter = filter;
        ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
-       if (ret)
-               tu->tp.flags &= ~flag;
+       if (ret) {
+               if (file) {
+                       list_del(&link->list);
+                       kfree(link);
+                       tu->tp.flags &= ~TP_FLAG_TRACE;
+               } else
+                       tu->tp.flags &= ~TP_FLAG_PROFILE;
+       }
 
        return ret;
 }
 
-static void probe_event_disable(struct trace_uprobe *tu, int flag)
+static void
+probe_event_disable(struct trace_uprobe *tu, struct ftrace_event_file *file)
 {
        if (!trace_probe_is_enabled(&tu->tp))
                return;
 
+       if (file) {
+               struct event_file_link *link;
+
+               link = find_event_file_link(&tu->tp, file);
+               if (!link)
+                       return;
+
+               list_del_rcu(&link->list);
+               /* synchronize with u{,ret}probe_trace_func */
+               synchronize_sched();
+               kfree(link);
+
+               if (!list_empty(&tu->tp.files))
+                       return;
+       }
+
        WARN_ON(!uprobe_filter_is_empty(&tu->filter));
 
        uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
-       tu->tp.flags &= ~flag;
+       tu->tp.flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;
 
        uprobe_buffer_disable();
 }
@@ -1077,25 +1138,27 @@ static void uretprobe_perf_func(struct trace_uprobe *tu, unsigned long func,
 }
 #endif /* CONFIG_PERF_EVENTS */
 
-static
-int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type, void *data)
+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: