@@ -202,6 +202,10 @@ struct trace_seq;
int ring_buffer_print_entry_header(struct trace_seq *s);
int ring_buffer_print_page_header(struct trace_buffer *buffer, struct trace_seq *s);
+int ring_buffer_subbuf_order_get(struct trace_buffer *buffer);
+int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order);
+int ring_buffer_subbuf_size_get(struct trace_buffer *buffer);
+
enum ring_buffer_flags {
RB_FL_OVERWRITE = 1 << 0,
};
@@ -524,6 +524,7 @@ struct trace_buffer {
bool time_stamp_abs;
unsigned int subbuf_size;
+ unsigned int subbuf_order;
unsigned int max_data_size;
};
@@ -5903,6 +5904,78 @@ int ring_buffer_read_page(struct trace_buffer *buffer,
}
EXPORT_SYMBOL_GPL(ring_buffer_read_page);
+/**
+ * ring_buffer_subbuf_size_get - get size of the sub buffer.
+ * @buffer: the buffer to get the sub buffer size from
+ *
+ * Returns size of the sub buffer, in bytes.
+ */
+int ring_buffer_subbuf_size_get(struct trace_buffer *buffer)
+{
+ return buffer->subbuf_size + BUF_PAGE_HDR_SIZE;
+}
+EXPORT_SYMBOL_GPL(ring_buffer_subbuf_size_get);
+
+/**
+ * ring_buffer_subbuf_order_get - get order of system sub pages in one buffer page.
+ * @buffer: The ring_buffer to get the system sub page order from
+ *
+ * By default, one ring buffer sub page equals to one system page. This parameter
+ * is configurable, per ring buffer. The size of the ring buffer sub page can be
+ * extended, but must be an order of system page size.
+ *
+ * Returns the order of buffer sub page size, in system pages:
+ * 0 means the sub buffer size is 1 system page and so forth.
+ * In case of an error < 0 is returned.
+ */
+int ring_buffer_subbuf_order_get(struct trace_buffer *buffer)
+{
+ if (!buffer)
+ return -EINVAL;
+
+ return buffer->subbuf_order;
+}
+EXPORT_SYMBOL_GPL(ring_buffer_subbuf_order_get);
+
+/**
+ * ring_buffer_subbuf_order_set - set the size of ring buffer sub page.
+ * @buffer: The ring_buffer to set the new page size.
+ * @order: Order of the system pages in one sub buffer page
+ *
+ * By default, one ring buffer pages equals to one system page. This API can be
+ * used to set new size of the ring buffer page. The size must be order of
+ * system page size, that's why the input parameter @order is the order of
+ * system pages that are allocated for one ring buffer page:
+ * 0 - 1 system page
+ * 1 - 2 system pages
+ * 3 - 4 system pages
+ * ...
+ *
+ * Returns 0 on success or < 0 in case of an error.
+ */
+int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order)
+{
+ int psize;
+
+ if (!buffer || order < 0)
+ return -EINVAL;
+
+ if (buffer->subbuf_order == order)
+ return 0;
+
+ psize = (1 << order) * PAGE_SIZE;
+ if (psize <= BUF_PAGE_HDR_SIZE)
+ return -EINVAL;
+
+ buffer->subbuf_order = order;
+ buffer->subbuf_size = psize - BUF_PAGE_HDR_SIZE;
+
+ /* Todo: reset the buffer with the new page size */
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(ring_buffer_subbuf_order_set);
+
/*
* We only allocate new buffers, never free them if the CPU goes down.
* If we were to free the buffer, then the user would lose any trace that was in
@@ -9352,6 +9352,51 @@ static const struct file_operations buffer_percent_fops = {
.llseek = default_llseek,
};
+static ssize_t
+buffer_order_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+ struct trace_array *tr = filp->private_data;
+ char buf[64];
+ int r;
+
+ r = sprintf(buf, "%d\n", ring_buffer_subbuf_order_get(tr->array_buffer.buffer));
+
+ return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static ssize_t
+buffer_order_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ struct trace_array *tr = filp->private_data;
+ unsigned long val;
+ int ret;
+
+ ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+ if (ret)
+ return ret;
+
+ /* limit between 1 and 128 system pages */
+ if (val < 0 || val > 7)
+ return -EINVAL;
+
+ ret = ring_buffer_subbuf_order_set(tr->array_buffer.buffer, val);
+ if (ret)
+ return ret;
+
+ (*ppos)++;
+
+ return cnt;
+}
+
+static const struct file_operations buffer_order_fops = {
+ .open = tracing_open_generic_tr,
+ .read = buffer_order_read,
+ .write = buffer_order_write,
+ .release = tracing_release_generic_tr,
+ .llseek = default_llseek,
+};
+
static struct dentry *trace_instance_dir;
static void
@@ -9818,6 +9863,9 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
trace_create_file("buffer_percent", TRACE_MODE_WRITE, d_tracer,
tr, &buffer_percent_fops);
+ trace_create_file("buffer_subbuf_order", TRACE_MODE_WRITE, d_tracer,
+ tr, &buffer_order_fops);
+
create_trace_options_dir(tr);
#ifdef CONFIG_TRACER_MAX_TRACE