copy_from_user and memset

[lttng-modules.git] / lib / ringbuffer / ring_buffer_backend.c

diff --git a/lib/ringbuffer/ring_buffer_backend.c b/lib/ringbuffer/ring_buffer_backend.c
index a9513d1c07e3072fc9e6f6dcd5418554a1af8255..d1b5b8cde5494909f748c28ab2e31583d5cfb2a1 100644 (file)
--- a/lib/ringbuffer/ring_buffer_backend.c
+++ b/lib/ringbuffer/ring_buffer_backend.c
@@ -501,6 +501,107 @@ void _lib_ring_buffer_write(struct lib_ring_buffer_backend *bufb, size_t offset,
 }
 EXPORT_SYMBOL_GPL(_lib_ring_buffer_write);
 
+
+/**
+ * lib_ring_buffer_memset - write len bytes of c to a ring_buffer buffer.
+ * @bufb : buffer backend
+ * @offset : offset within the buffer
+ * @c : the byte to write
+ * @len : length to write
+ * @pagecpy : page size copied so far
+ */
+void _lib_ring_buffer_memset(struct lib_ring_buffer_backend *bufb,
+                            size_t offset,
+                            int c, size_t len, ssize_t pagecpy)
+{
+       struct channel_backend *chanb = &bufb->chan->backend;
+       const struct lib_ring_buffer_config *config = chanb->config;
+       size_t sbidx, index;
+       struct lib_ring_buffer_backend_pages *rpages;
+       unsigned long sb_bindex, id;
+
+       do {
+               len -= pagecpy;
+               offset += pagecpy;
+               sbidx = offset >> chanb->subbuf_size_order;
+               index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
+
+               /*
+                * Underlying layer should never ask for writes across
+                * subbuffers.
+                */
+               CHAN_WARN_ON(chanb, offset >= chanb->buf_size);
+
+               pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
+               id = bufb->buf_wsb[sbidx].id;
+               sb_bindex = subbuffer_id_get_index(config, id);
+               rpages = bufb->array[sb_bindex];
+               CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
+                            && subbuffer_id_is_noref(config, id));
+               lib_ring_buffer_do_memset(rpages->p[index].virt
+                                         + (offset & ~PAGE_MASK),
+                                         c, pagecpy);
+       } while (unlikely(len != pagecpy));
+}
+EXPORT_SYMBOL_GPL(_lib_ring_buffer_memset);
+
+
+/**
+ * lib_ring_buffer_copy_from_user - write user data to a ring_buffer buffer.
+ * @bufb : buffer backend
+ * @offset : offset within the buffer
+ * @src : source address
+ * @len : length to write
+ * @pagecpy : page size copied so far
+ *
+ * This function deals with userspace pointers, it should never be called
+ * directly without having the src pointer checked with access_ok()
+ * previously.
+ */
+void _lib_ring_buffer_copy_from_user(struct lib_ring_buffer_backend *bufb,
+                                     size_t offset,
+                                     const void __user *src, size_t len,
+                                     ssize_t pagecpy)
+{
+       struct channel_backend *chanb = &bufb->chan->backend;
+       const struct lib_ring_buffer_config *config = chanb->config;
+       size_t sbidx, index;
+       struct lib_ring_buffer_backend_pages *rpages;
+       unsigned long sb_bindex, id;
+       int ret;
+
+       do {
+               len -= pagecpy;
+               src += pagecpy;
+               offset += pagecpy;
+               sbidx = offset >> chanb->subbuf_size_order;
+               index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
+
+               /*
+                * Underlying layer should never ask for writes across
+                * subbuffers.
+                */
+               CHAN_WARN_ON(chanb, offset >= chanb->buf_size);
+
+               pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
+               id = bufb->buf_wsb[sbidx].id;
+               sb_bindex = subbuffer_id_get_index(config, id);
+               rpages = bufb->array[sb_bindex];
+               CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
+                               && subbuffer_id_is_noref(config, id));
+               ret = lib_ring_buffer_do_copy_from_user(rpages->p[index].virt
+                                                       + (offset & ~PAGE_MASK),
+                                                       src, pagecpy) != 0;
+               if (ret > 0) {
+                       offset += (pagecpy - ret);
+                       len -= (pagecpy - ret);
+                       _lib_ring_buffer_memset(bufb, offset, 0, len, 0);
+                       break; /* stop copy */
+               }
+       } while (unlikely(len != pagecpy));
+}
+EXPORT_SYMBOL_GPL(_lib_ring_buffer_copy_from_user);
+
 /**
  * lib_ring_buffer_read - read data from ring_buffer_buffer.
  * @bufb : buffer backend