spl: Add generic spl_load function

Implementers of SPL_LOAD_IMAGE_METHOD have to correctly determine what
type of image is being loaded and then call the appropriate image load
function correctly. This is tricky, because some image load functions
expect the whole image to already be loaded (CONFIG_SPL_LOAD_FIT_FULL),
some will load the image automatically using spl_load_info.read()
(CONFIG_SPL_LOAD_FIT/CONFIG_SPL_LOAD_IMX_CONTAINER), and some just parse
the header and expect the caller to do the actual loading afterwards
(legacy/raw images). Load methods often only support a subset of the
above methods, meaning that not all image types can be used with all
load methods. Further, the code to invoke these functions is
duplicated between different load functions.

To address this problem, this commit introduces a "spl_load" function.
It aims to handle image detection and correct invocation of each of the
parse/load functions.

Although this function generally results in a size reduction with
several users, it tends to bloat boards with only a single user.
This is generally because programmers open-coding the contents of this
function can make optimizations based on the specific loader. For
example, NOR flash is memory-mapped, so it never bothers calling
load->read. The compiler can't really make these optimizations across
translation units. LTO solves this, but it is only available on some
arches. To address this, perform "pseudo-LTO" by inlining spl_load when
there are one or fewer users. At the moment, there are no users, so
define SPL_LOAD_USERS to be 0.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

1 files changed, 135 insertions, 0 deletions

diff --git a/include/spl_load.h b/include/spl_load.h
new file mode 100644
index 0000000..406f8b5
--- /dev/null
+++ b/include/spl_load.h
@@ -0,0 +1,135 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) Sean Anderson <seanga2@gmail.com>
+ */
+#ifndef	_SPL_LOAD_H_
+#define	_SPL_LOAD_H_
+
+#include <image.h>
+#include <imx_container.h>
+#include <mapmem.h>
+#include <spl.h>
+
+static inline int _spl_load(struct spl_image_info *spl_image,
+			    const struct spl_boot_device *bootdev,
+			    struct spl_load_info *info, size_t size,
+			    size_t offset)
+{
+	struct legacy_img_hdr *header =
+		spl_get_load_buffer(-sizeof(*header), sizeof(*header));
+	ulong base_offset, image_offset, overhead;
+	int read, ret;
+
+	read = info->read(info, offset, ALIGN(sizeof(*header),
+					      spl_get_bl_len(info)), header);
+	if (read < sizeof(*header))
+		return -EIO;
+
+	if (image_get_magic(header) == FDT_MAGIC) {
+		if (IS_ENABLED(CONFIG_SPL_LOAD_FIT_FULL)) {
+			void *buf;
+
+			/*
+			 * In order to support verifying images in the FIT, we
+			 * need to load the whole FIT into memory. Try and
+			 * guess how much we need to load by using the total
+			 * size. This will fail for FITs with external data,
+			 * but there's not much we can do about that.
+			 */
+			if (!size)
+				size = round_up(fdt_totalsize(header), 4);
+			buf = map_sysmem(CONFIG_SYS_LOAD_ADDR, size);
+			read = info->read(info, offset,
+					  ALIGN(size, spl_get_bl_len(info)),
+					  buf);
+			if (read < size)
+				return -EIO;
+
+			return spl_parse_image_header(spl_image, bootdev, buf);
+		}
+
+		if (IS_ENABLED(CONFIG_SPL_LOAD_FIT))
+			return spl_load_simple_fit(spl_image, info, offset,
+						   header);
+	}
+
+	if (IS_ENABLED(CONFIG_SPL_LOAD_IMX_CONTAINER) &&
+	    valid_container_hdr((void *)header))
+		return spl_load_imx_container(spl_image, info, offset);
+
+	if (IS_ENABLED(CONFIG_SPL_LZMA) &&
+	    image_get_magic(header) == IH_MAGIC &&
+	    image_get_comp(header) == IH_COMP_LZMA) {
+		spl_image->flags |= SPL_COPY_PAYLOAD_ONLY;
+		ret = spl_parse_image_header(spl_image, bootdev, header);
+		if (ret)
+			return ret;
+
+		return spl_load_legacy_lzma(spl_image, info, offset);
+	}
+
+	ret = spl_parse_image_header(spl_image, bootdev, header);
+	if (ret)
+		return ret;
+
+	base_offset = spl_image->offset;
+	/* Only NOR sets this flag. */
+	if (IS_ENABLED(CONFIG_SPL_NOR_SUPPORT) &&
+	    spl_image->flags & SPL_COPY_PAYLOAD_ONLY)
+		base_offset += sizeof(*header);
+	image_offset = ALIGN_DOWN(base_offset, spl_get_bl_len(info));
+	overhead = base_offset - image_offset;
+	size = ALIGN(spl_image->size + overhead, spl_get_bl_len(info));
+
+	read = info->read(info, offset + image_offset, size,
+			  map_sysmem(spl_image->load_addr - overhead, size));
+	return read < spl_image->size ? -EIO : 0;
+}
+
+/*
+ * Although spl_load results in size reduction for callers, this is generally
+ * not enough to counteract the bloat if there is only one caller. The core
+ * problem is that the compiler can't optimize across translation units. The
+ * general solution to this is CONFIG_LTO, but that is not available on all
+ * architectures. Perform a pseudo-LTO just for this function by declaring it
+ * inline if there is one caller, and extern otherwise.
+ */
+#define SPL_LOAD_USERS \
+	0
+
+#if SPL_LOAD_USERS > 1
+/**
+ * spl_load() - Parse a header and load the image
+ * @spl_image: Image data which will be filled in by this function
+ * @bootdev: The device to load from
+ * @info: Describes how to load additional information from @bootdev. At the
+ *        minimum, read() and bl_len must be populated.
+ * @size: The size of the image, in bytes, if it is known in advance. Some boot
+ *        devices (such as filesystems) know how big an image is before parsing
+ *        the header. If 0, then the size will be determined from the header.
+ * @offset: The offset from the start of @bootdev, in bytes. This should have
+ *          the offset @header was loaded from. It will be added to any offsets
+ *          passed to @info->read().
+ *
+ * This function determines the image type (FIT, legacy, i.MX, raw, etc), calls
+ * the appropriate parsing function, determines the load address, and the loads
+ * the image from storage. It is designed to replace ad-hoc image loading which
+ * may not support all image types (especially when config options are
+ * involved).
+ *
+ * Return: 0 on success, or a negative error on failure
+ */
+int spl_load(struct spl_image_info *spl_image,
+	     const struct spl_boot_device *bootdev, struct spl_load_info *info,
+	     size_t size, size_t offset);
+#else
+static inline int spl_load(struct spl_image_info *spl_image,
+			   const struct spl_boot_device *bootdev,
+			   struct spl_load_info *info, size_t size,
+			   size_t offset)
+{
+	return _spl_load(spl_image, bootdev, info, size, offset);
+}
+#endif
+
+#endif /* _SPL_LOAD_H_ */