3 files changed, 123 insertions, 15 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d38c16a06a6f..e0e14ce0caab 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2013,9 +2013,10 @@ enum print_line_t print_trace_line(struct trace_iterator *iter)
 {
         enum print_line_t ret;
 
-        if (iter->lost_events)
-                trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
-                                 iter->cpu, iter->lost_events);
+        if (iter->lost_events &&
+            !trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
+                                 iter->cpu, iter->lost_events))
+                return TRACE_TYPE_PARTIAL_LINE;
 
         if (iter->trace && iter->trace->print_line) {
                 ret = iter->trace->print_line(iter);
@@ -3229,6 +3230,14 @@ waitagain:
 
                 if (iter->seq.len >= cnt)
                         break;
+
+                /*
+                 * Setting the full flag means we reached the trace_seq buffer
+                 * size and we should leave by partial output condition above.
+                 * One of the trace_seq_* functions is not used properly.
+                 */
+                WARN_ONCE(iter->seq.full, "full flag set for trace type %d",
+                          iter->ent->type);
         }
         trace_access_unlock(iter->cpu_file);
         trace_event_read_unlock();
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 456be9063c2d..cf535ccedc86 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -830,6 +830,9 @@ EXPORT_SYMBOL_GPL(unregister_ftrace_event);
 enum print_line_t trace_nop_print(struct trace_iterator *iter, int flags,
                                   struct trace_event *event)
 {
+        if (!trace_seq_printf(&iter->seq, "type: %d\n", iter->ent->type))
+                return TRACE_TYPE_PARTIAL_LINE;
+
         return TRACE_TYPE_HANDLED;
 }
 
diff --git a/kernel/trace/trace_printk.c b/kernel/trace/trace_printk.c
index 2547d8813cf0..dff763b7baf1 100644
--- a/kernel/trace/trace_printk.c
+++ b/kernel/trace/trace_printk.c
@@ -32,7 +32,7 @@ static DEFINE_MUTEX(btrace_mutex);
 
 struct trace_bprintk_fmt {
         struct list_head list;
-        char fmt[0];
+        const char *fmt;
 };
 
 static inline struct trace_bprintk_fmt *lookup_format(const char *fmt)
@@ -49,6 +49,7 @@ static
 void hold_module_trace_bprintk_format(const char **start, const char **end)
 {
         const char **iter;
+        char *fmt;
 
         mutex_lock(&btrace_mutex);
         for (iter = start; iter < end; iter++) {
@@ -58,14 +59,18 @@ void hold_module_trace_bprintk_format(const char **start, const char **end)
                         continue;
                 }
 
-                tb_fmt = kmalloc(offsetof(struct trace_bprintk_fmt, fmt)
-                                + strlen(*iter) + 1, GFP_KERNEL);
-                if (tb_fmt) {
+                tb_fmt = kmalloc(sizeof(*tb_fmt), GFP_KERNEL);
+                if (tb_fmt)
+                        fmt = kmalloc(strlen(*iter) + 1, GFP_KERNEL);
+                if (tb_fmt && fmt) {
                         list_add_tail(&tb_fmt->list, &trace_bprintk_fmt_list);
-                        strcpy(tb_fmt->fmt, *iter);
+                        strcpy(fmt, *iter);
+                        tb_fmt->fmt = fmt;
                         *iter = tb_fmt->fmt;
-                } else
+                } else {
+                        kfree(tb_fmt);
                         *iter = NULL;
+                }
         }
         mutex_unlock(&btrace_mutex);
 }
@@ -84,6 +89,76 @@ static int module_trace_bprintk_format_notify(struct notifier_block *self,
         return 0;
 }
 
+/*
+ * The debugfs/tracing/printk_formats file maps the addresses with
+ * the ASCII formats that are used in the bprintk events in the
+ * buffer. For userspace tools to be able to decode the events from
+ * the buffer, they need to be able to map the address with the format.
+ *
+ * The addresses of the bprintk formats are in their own section
+ * __trace_printk_fmt. But for modules we copy them into a link list.
+ * The code to print the formats and their addresses passes around the
+ * address of the fmt string. If the fmt address passed into the seq
+ * functions is within the kernel core __trace_printk_fmt section, then
+ * it simply uses the next pointer in the list.
+ *
+ * When the fmt pointer is outside the kernel core __trace_printk_fmt
+ * section, then we need to read the link list pointers. The trick is
+ * we pass the address of the string to the seq function just like
+ * we do for the kernel core formats. To get back the structure that
+ * holds the format, we simply use containerof() and then go to the
+ * next format in the list.
+ */
+static const char **
+find_next_mod_format(int start_index, void *v, const char **fmt, loff_t *pos)
+{
+        struct trace_bprintk_fmt *mod_fmt;
+
+        if (list_empty(&trace_bprintk_fmt_list))
+                return NULL;
+
+        /*
+         * v will point to the address of the fmt record from t_next
+         * v will be NULL from t_start.
+         * If this is the first pointer or called from start
+         * then we need to walk the list.
+         */
+        if (!v || start_index == *pos) {
+                struct trace_bprintk_fmt *p;
+
+                /* search the module list */
+                list_for_each_entry(p, &trace_bprintk_fmt_list, list) {
+                        if (start_index == *pos)
+                                return &p->fmt;
+                        start_index++;
+                }
+                /* pos > index */
+                return NULL;
+        }
+
+        /*
+         * v points to the address of the fmt field in the mod list
+         * structure that holds the module print format.
+         */
+        mod_fmt = container_of(v, typeof(*mod_fmt), fmt);
+        if (mod_fmt->list.next == &trace_bprintk_fmt_list)
+                return NULL;
+
+        mod_fmt = container_of(mod_fmt->list.next, typeof(*mod_fmt), list);
+
+        return &mod_fmt->fmt;
+}
+
+static void format_mod_start(void)
+{
+        mutex_lock(&btrace_mutex);
+}
+
+static void format_mod_stop(void)
+{
+        mutex_unlock(&btrace_mutex);
+}
+
 #else /* !CONFIG_MODULES */
 __init static int
 module_trace_bprintk_format_notify(struct notifier_block *self,
@@ -91,6 +166,13 @@ module_trace_bprintk_format_notify(struct notifier_block *self,
 {
         return 0;
 }
+static inline const char **
+find_next_mod_format(int start_index, void *v, const char **fmt, loff_t *pos)
+{
+        return NULL;
+}
+static inline void format_mod_start(void) { }
+static inline void format_mod_stop(void) { }
 #endif /* CONFIG_MODULES */
 
 
@@ -153,20 +235,33 @@ int __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap)
 }
 EXPORT_SYMBOL_GPL(__ftrace_vprintk);
 
+static const char **find_next(void *v, loff_t *pos)
+{
+        const char **fmt = v;
+        int start_index;
+
+        if (!fmt)
+                fmt = __start___trace_bprintk_fmt + *pos;
+
+        start_index = __stop___trace_bprintk_fmt - __start___trace_bprintk_fmt;
+
+        if (*pos < start_index)
+                return fmt;
+
+        return find_next_mod_format(start_index, v, fmt, pos);
+}
+
 static void *
 t_start(struct seq_file *m, loff_t *pos)
 {
-        const char **fmt = __start___trace_bprintk_fmt + *pos;
-
-        if ((unsigned long)fmt >= (unsigned long)__stop___trace_bprintk_fmt)
-                return NULL;
-        return fmt;
+        format_mod_start();
+        return find_next(NULL, pos);
 }
 
 static void *t_next(struct seq_file *m, void * v, loff_t *pos)
 {
         (*pos)++;
-        return t_start(m, pos);
+        return find_next(v, pos);
 }
 
 static int t_show(struct seq_file *m, void *v)
@@ -205,6 +300,7 @@ static int t_show(struct seq_file *m, void *v)
 
 static void t_stop(struct seq_file *m, void *p)
 {
+        format_mod_stop();
 }
 
 static const struct seq_operations show_format_seq_ops = {