ctx->buf_offset += len;
}
+/*
+ * Copy up to @len string bytes from @src to @dest. Stop whenever a NULL
+ * terminating character is found in @src. Returns the number of bytes
+ * copied. Does *not* terminate @dest with NULL terminating character.
+ */
+static inline
+size_t lib_ring_buffer_do_strcpy(const struct lib_ring_buffer_config *config,
+ char *dest, const char *src, size_t len)
+{
+ size_t count;
+
+ for (count = 0; count < len; count++) {
+ char c;
+
+ /*
+ * Only read source character once, in case it is
+ * modified concurrently.
+ */
+ c = ACCESS_ONCE(src[count]);
+ if (!c)
+ break;
+ lib_ring_buffer_do_copy(config, &dest[count], &c, 1);
+ }
+ return count;
+}
+
+/*
+ * Copy up to @len string bytes from @src to @dest. Stop whenever a NULL
+ * terminating character is found in @src, or when a fault occurs.
+ * Returns the number of bytes copied. Does *not* terminate @dest with
+ * NULL terminating character.
+ *
+ * This function deals with userspace pointers, it should never be called
+ * directly without having the src pointer checked with access_ok()
+ * previously.
+ */
+static inline
+size_t lib_ring_buffer_do_strcpy_from_user_inatomic(const struct lib_ring_buffer_config *config,
+ char *dest, const char __user *src, size_t len)
+{
+ size_t count;
+
+ for (count = 0; count < len; count++) {
+ int ret;
+ char c;
+
+ ret = __get_user(c, &src[count]);
+ if (ret || !c)
+ break;
+ lib_ring_buffer_do_copy(config, &dest[count], &c, 1);
+ }
+ return count;
+}
+
+/**
+ * lib_ring_buffer_strcpy - write string data to a buffer backend
+ * @config : ring buffer instance configuration
+ * @ctx: ring buffer context. (input arguments only)
+ * @src : source pointer to copy from
+ * @len : length of data to copy
+ * @pad : character to use for padding
+ *
+ * This function copies @len - 1 bytes of string data from a source
+ * pointer to a buffer backend, followed by a terminating '\0'
+ * character, at the current context offset. This is more or less a
+ * buffer backend-specific strncpy() operation. If a terminating '\0'
+ * character is found in @src before @len - 1 characters are copied, pad
+ * the buffer with @pad characters (e.g. '#'). Calls the slow path
+ * (_ring_buffer_strcpy) if copy is crossing a page boundary.
+ */
+static inline
+void lib_ring_buffer_strcpy(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_ctx *ctx,
+ const char *src, size_t len, int pad)
+{
+ struct lib_ring_buffer_backend *bufb = &ctx->buf->backend;
+ struct channel_backend *chanb = &ctx->chan->backend;
+ size_t sbidx, index, pagecpy;
+ size_t offset = ctx->buf_offset;
+ struct lib_ring_buffer_backend_pages *rpages;
+ unsigned long sb_bindex, id;
+
+ if (unlikely(!len))
+ return;
+ offset &= chanb->buf_size - 1;
+ sbidx = offset >> chanb->subbuf_size_order;
+ index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
+ pagecpy = min_t(size_t, len, (-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(ctx->chan,
+ config->mode == RING_BUFFER_OVERWRITE
+ && subbuffer_id_is_noref(config, id));
+ if (likely(pagecpy == len)) {
+ size_t count;
+
+ count = lib_ring_buffer_do_strcpy(config,
+ rpages->p[index].virt
+ + (offset & ~PAGE_MASK),
+ src, len - 1);
+ offset += count;
+ /* Padding */
+ if (unlikely(count < len - 1)) {
+ size_t pad_len = len - 1 - count;
+
+ lib_ring_buffer_do_memset(rpages->p[index].virt
+ + (offset & ~PAGE_MASK),
+ pad, pad_len);
+ offset += pad_len;
+ }
+ /* Ending '\0' */
+ lib_ring_buffer_do_memset(rpages->p[index].virt
+ + (offset & ~PAGE_MASK),
+ '\0', 1);
+ } else {
+ _lib_ring_buffer_strcpy(bufb, offset, src, len, 0, pad);
+ }
+ ctx->buf_offset += len;
+}
+
/**
* lib_ring_buffer_copy_from_user_inatomic - write userspace data to a buffer backend
* @config : ring buffer instance configuration
_lib_ring_buffer_memset(bufb, offset, 0, len, 0);
}
+/**
+ * lib_ring_buffer_strcpy_from_user_inatomic - write userspace string data to a buffer backend
+ * @config : ring buffer instance configuration
+ * @ctx: ring buffer context (input arguments only)
+ * @src : userspace source pointer to copy from
+ * @len : length of data to copy
+ * @pad : character to use for padding
+ *
+ * This function copies @len - 1 bytes of string data from a userspace
+ * source pointer to a buffer backend, followed by a terminating '\0'
+ * character, at the current context offset. This is more or less a
+ * buffer backend-specific strncpy() operation. If a terminating '\0'
+ * character is found in @src before @len - 1 characters are copied, pad
+ * the buffer with @pad characters (e.g. '#'). Calls the slow path
+ * (_ring_buffer_strcpy_from_user_inatomic) if copy is crossing a page
+ * boundary. Disable the page fault handler to ensure we never try to
+ * take the mmap_sem.
+ */
+static inline
+void lib_ring_buffer_strcpy_from_user_inatomic(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_ctx *ctx,
+ const void __user *src, size_t len, int pad)
+{
+ struct lib_ring_buffer_backend *bufb = &ctx->buf->backend;
+ struct channel_backend *chanb = &ctx->chan->backend;
+ size_t sbidx, index, pagecpy;
+ size_t offset = ctx->buf_offset;
+ struct lib_ring_buffer_backend_pages *rpages;
+ unsigned long sb_bindex, id;
+ mm_segment_t old_fs = get_fs();
+
+ if (unlikely(!len))
+ return;
+ offset &= chanb->buf_size - 1;
+ sbidx = offset >> chanb->subbuf_size_order;
+ index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
+ pagecpy = min_t(size_t, len, (-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(ctx->chan,
+ config->mode == RING_BUFFER_OVERWRITE
+ && subbuffer_id_is_noref(config, id));
+
+ set_fs(KERNEL_DS);
+ pagefault_disable();
+ if (unlikely(!access_ok(VERIFY_READ, src, len)))
+ goto fill_buffer;
+
+ if (likely(pagecpy == len)) {
+ size_t count;
+
+ count = lib_ring_buffer_do_strcpy_from_user_inatomic(config,
+ rpages->p[index].virt
+ + (offset & ~PAGE_MASK),
+ src, len - 1);
+ offset += count;
+ /* Padding */
+ if (unlikely(count < len - 1)) {
+ size_t pad_len = len - 1 - count;
+
+ lib_ring_buffer_do_memset(rpages->p[index].virt
+ + (offset & ~PAGE_MASK),
+ pad, pad_len);
+ offset += pad_len;
+ }
+ /* Ending '\0' */
+ lib_ring_buffer_do_memset(rpages->p[index].virt
+ + (offset & ~PAGE_MASK),
+ '\0', 1);
+ } else {
+ _lib_ring_buffer_strcpy_from_user_inatomic(bufb, offset, src,
+ len, 0, pad);
+ }
+ pagefault_enable();
+ set_fs(old_fs);
+ ctx->buf_offset += len;
+
+ return;
+
+fill_buffer:
+ pagefault_enable();
+ set_fs(old_fs);
+ /*
+ * In the error path we call the slow path version to avoid
+ * the pollution of static inline code.
+ */
+ _lib_ring_buffer_memset(bufb, offset, pad, len - 1, 0);
+ offset += len - 1;
+ _lib_ring_buffer_memset(bufb, offset, '\0', 1, 0);
+}
+
/*
* This accessor counts the number of unread records in a buffer.
* It only provides a consistent value if no reads not writes are performed
projects / lttng-modules.git / blobdiff