tracing: Add new trace_marker_raw
A new file is created:
/sys/kernel/debug/tracing/trace_marker_raw
This allows for appications to create data structures and write the binary
data directly into it, and then read the trace data out from trace_pipe_raw
into the same type of data structure. This saves on converting numbers into
ASCII that would be required by trace_marker.
Suggested-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d904516d..57069e7 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4054,6 +4054,7 @@ static const char readme_msg[] =
" x86-tsc: TSC cycle counter\n"
#endif
"\n trace_marker\t\t- Writes into this file writes into the kernel buffer\n"
+ "\n trace_marker_raw\t\t- Writes into this file writes binary data into the kernel buffer\n"
" tracing_cpumask\t- Limit which CPUs to trace\n"
" instances\t\t- Make sub-buffers with: mkdir instances/foo\n"
"\t\t\t Remove sub-buffer with rmdir\n"
@@ -5514,35 +5515,15 @@ tracing_free_buffer_release(struct inode *inode, struct file *filp)
return 0;
}
-static ssize_t
-tracing_mark_write(struct file *filp, const char __user *ubuf,
- size_t cnt, loff_t *fpos)
+static inline int lock_user_pages(const char __user *ubuf, size_t cnt,
+ struct page **pages, void **map_page,
+ int *offset)
{
unsigned long addr = (unsigned long)ubuf;
- struct trace_array *tr = filp->private_data;
- struct ring_buffer_event *event;
- struct ring_buffer *buffer;
- struct print_entry *entry;
- unsigned long irq_flags;
- struct page *pages[2];
- void *map_page[2];
int nr_pages = 1;
- ssize_t written;
- int offset;
- int size;
- int len;
int ret;
int i;
- if (tracing_disabled)
- return -EINVAL;
-
- if (!(tr->trace_flags & TRACE_ITER_MARKERS))
- return -EINVAL;
-
- if (cnt > TRACE_BUF_SIZE)
- cnt = TRACE_BUF_SIZE;
-
/*
* Userspace is injecting traces into the kernel trace buffer.
* We want to be as non intrusive as possible.
@@ -5557,26 +5538,70 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
* pages directly. We then write the data directly into the
* ring buffer.
*/
- BUILD_BUG_ON(TRACE_BUF_SIZE >= PAGE_SIZE);
/* check if we cross pages */
if ((addr & PAGE_MASK) != ((addr + cnt) & PAGE_MASK))
nr_pages = 2;
- offset = addr & (PAGE_SIZE - 1);
+ *offset = addr & (PAGE_SIZE - 1);
addr &= PAGE_MASK;
ret = get_user_pages_fast(addr, nr_pages, 0, pages);
if (ret < nr_pages) {
while (--ret >= 0)
put_page(pages[ret]);
- written = -EFAULT;
- goto out;
+ return -EFAULT;
}
for (i = 0; i < nr_pages; i++)
map_page[i] = kmap_atomic(pages[i]);
+ return nr_pages;
+}
+
+static inline void unlock_user_pages(struct page **pages,
+ void **map_page, int nr_pages)
+{
+ int i;
+
+ for (i = nr_pages - 1; i >= 0; i--) {
+ kunmap_atomic(map_page[i]);
+ put_page(pages[i]);
+ }
+}
+
+static ssize_t
+tracing_mark_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *fpos)
+{
+ struct trace_array *tr = filp->private_data;
+ struct ring_buffer_event *event;
+ struct ring_buffer *buffer;
+ struct print_entry *entry;
+ unsigned long irq_flags;
+ struct page *pages[2];
+ void *map_page[2];
+ int nr_pages = 1;
+ ssize_t written;
+ int offset;
+ int size;
+ int len;
+
+ if (tracing_disabled)
+ return -EINVAL;
+
+ if (!(tr->trace_flags & TRACE_ITER_MARKERS))
+ return -EINVAL;
+
+ if (cnt > TRACE_BUF_SIZE)
+ cnt = TRACE_BUF_SIZE;
+
+ BUILD_BUG_ON(TRACE_BUF_SIZE >= PAGE_SIZE);
+
+ nr_pages = lock_user_pages(ubuf, cnt, pages, map_page, &offset);
+ if (nr_pages < 0)
+ return nr_pages;
+
local_save_flags(irq_flags);
size = sizeof(*entry) + cnt + 2; /* possible \n added */
buffer = tr->trace_buffer.buffer;
@@ -5611,11 +5636,79 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
*fpos += written;
out_unlock:
- for (i = nr_pages - 1; i >= 0; i--) {
- kunmap_atomic(map_page[i]);
- put_page(pages[i]);
+ unlock_user_pages(pages, map_page, nr_pages);
+
+ return written;
+}
+
+/* Limit it for now to 3K (including tag) */
+#define RAW_DATA_MAX_SIZE (1024*3)
+
+static ssize_t
+tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *fpos)
+{
+ struct trace_array *tr = filp->private_data;
+ struct ring_buffer_event *event;
+ struct ring_buffer *buffer;
+ struct raw_data_entry *entry;
+ unsigned long irq_flags;
+ struct page *pages[2];
+ void *map_page[2];
+ int nr_pages = 1;
+ ssize_t written;
+ int offset;
+ int size;
+ int len;
+
+ if (tracing_disabled)
+ return -EINVAL;
+
+ if (!(tr->trace_flags & TRACE_ITER_MARKERS))
+ return -EINVAL;
+
+ /* The marker must at least have a tag id */
+ if (cnt < sizeof(unsigned int) || cnt > RAW_DATA_MAX_SIZE)
+ return -EINVAL;
+
+ if (cnt > TRACE_BUF_SIZE)
+ cnt = TRACE_BUF_SIZE;
+
+ BUILD_BUG_ON(TRACE_BUF_SIZE >= PAGE_SIZE);
+
+ nr_pages = lock_user_pages(ubuf, cnt, pages, map_page, &offset);
+ if (nr_pages < 0)
+ return nr_pages;
+
+ local_save_flags(irq_flags);
+ size = sizeof(*entry) + cnt;
+ buffer = tr->trace_buffer.buffer;
+ event = trace_buffer_lock_reserve(buffer, TRACE_RAW_DATA, size,
+ irq_flags, preempt_count());
+ if (!event) {
+ /* Ring buffer disabled, return as if not open for write */
+ written = -EBADF;
+ goto out_unlock;
}
- out:
+
+ entry = ring_buffer_event_data(event);
+
+ if (nr_pages == 2) {
+ len = PAGE_SIZE - offset;
+ memcpy(&entry->id, map_page[0] + offset, len);
+ memcpy(((char *)&entry->id) + len, map_page[1], cnt - len);
+ } else
+ memcpy(&entry->id, map_page[0] + offset, cnt);
+
+ __buffer_unlock_commit(buffer, event);
+
+ written = cnt;
+
+ *fpos += written;
+
+ out_unlock:
+ unlock_user_pages(pages, map_page, nr_pages);
+
return written;
}
@@ -5945,6 +6038,13 @@ static const struct file_operations tracing_mark_fops = {
.release = tracing_release_generic_tr,
};
+static const struct file_operations tracing_mark_raw_fops = {
+ .open = tracing_open_generic_tr,
+ .write = tracing_mark_raw_write,
+ .llseek = generic_file_llseek,
+ .release = tracing_release_generic_tr,
+};
+
static const struct file_operations trace_clock_fops = {
.open = tracing_clock_open,
.read = seq_read,
@@ -7214,6 +7314,9 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
trace_create_file("trace_marker", 0220, d_tracer,
tr, &tracing_mark_fops);
+ trace_create_file("trace_marker_raw", 0220, d_tracer,
+ tr, &tracing_mark_raw_fops);
+
trace_create_file("trace_clock", 0644, d_tracer, tr,
&trace_clock_fops);