spl: Weed out CONFIG_SYS_TEXT_BASE usage

The SPL loaders assume that the CONFIG_SYS_TEXT_BASE memory location
is available and can be corrupted by loading ie. uImage or fitImage
headers there. Sometimes it could be beneficial to load the headers
elsewhere, ie. if CONFIG_SYS_TEXT_BASE is not yet writable while we
still want to parse the image headers in some local onchip memory to
ie. extract firmware from that image.

Add the possibility to override the location where the headers get
loaded by introducing new function, spl_get_load_buffer() which takes
two arguments -- offset from the CONFIG_SYS_TEXT_BASE and size of the
data that are to be loaded there -- and returns a valid buffer address
or hangs the system. The default behavior is the same as before, add
the offset to CONFIG_SYS_TEXT_BASE and return that address. User can
override the weak spl_get_load_buffer() function though.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>

common/spl/spl.c

@@ -127,6 +127,11 @@ __weak void spl_board_prepare_for_boot(void)
 	/* Nothing to do! */
 }
 
+__weak struct image_header *spl_get_load_buffer(ssize_t offset, size_t size)
+{
+	return (struct image_header *)(CONFIG_SYS_TEXT_BASE + offset);
+}
+
 void spl_set_header_raw_uboot(struct spl_image_info *spl_image)
 {
 	ulong u_boot_pos = binman_sym(ulong, u_boot_any, image_pos);

common/spl/spl_ext.c

@@ -16,8 +16,7 @@ int spl_load_image_ext(struct spl_image_info *spl_image,
 	loff_t filelen, actlen;
 	disk_partition_t part_info = {};
 
-	header = (struct image_header *)(CONFIG_SYS_TEXT_BASE -
-						sizeof(struct image_header));
+	header = spl_get_load_buffer(-sizeof(*header), sizeof(*header));
 
 	if (part_get_info(block_dev, partition, &part_info)) {
 		printf("spl: no partition table found\n");

common/spl/spl_fat.c

@@ -63,8 +63,7 @@ int spl_load_image_fat(struct spl_image_info *spl_image,
 	if (err)
 		goto end;
 
-	header = (struct image_header *)(CONFIG_SYS_TEXT_BASE -
-						sizeof(struct image_header));
+	header = spl_get_load_buffer(-sizeof(*header), sizeof(*header));
 
 	err = file_fat_read(filename, header, sizeof(struct image_header));
 	if (err <= 0)

common/spl/spl_fit.c

@@ -357,7 +357,7 @@ int spl_load_simple_fit(struct spl_image_info *spl_image,
 	struct spl_image_info image_info;
 	int node = -1;
 	int images, ret;
-	int base_offset, align_len = ARCH_DMA_MINALIGN - 1;
+	int base_offset, hsize, align_len = ARCH_DMA_MINALIGN - 1;
 	int index = 0;
 
 	/*
@@ -386,8 +386,8 @@ int spl_load_simple_fit(struct spl_image_info *spl_image,
 	 * For FIT with data embedded, data is loaded as part of FIT image.
 	 * For FIT with external data, data is not loaded in this step.
 	 */
-	fit = (void *)((CONFIG_SYS_TEXT_BASE - size - info->bl_len -
-			align_len) & ~align_len);
+	hsize = (size + info->bl_len + align_len) & ~align_len;
+	fit = spl_get_load_buffer(-hsize, hsize);
 	sectors = get_aligned_image_size(info, size, 0);
 	count = info->read(info, sector, sectors, fit);
 	debug("fit read sector %lx, sectors=%d, dst=%p, count=%lu\n",

common/spl/spl_mmc.c

@@ -55,13 +55,13 @@ int mmc_load_image_raw_sector(struct spl_image_info *spl_image,
 {
 	unsigned long count;
 	struct image_header *header;
+	struct blk_desc *bd = mmc_get_blk_desc(mmc);
 	int ret = 0;
 
-	header = (struct image_header *)(CONFIG_SYS_TEXT_BASE -
-					 sizeof(struct image_header));
+	header = spl_get_load_buffer(-sizeof(*header), bd->blksz);
 
 	/* read image header to find the image size & load address */
-	count = blk_dread(mmc_get_blk_desc(mmc), sector, 1, header);
+	count = blk_dread(bd, sector, 1, header);
 	debug("hdr read sector %lx, count=%lu\n", sector, count);
 	if (count == 0) {
 		ret = -EIO;

common/spl/spl_nand.c

@@ -83,8 +83,8 @@ static int spl_nand_load_image(struct spl_image_info *spl_image,
 #endif
 	nand_init();
 
-	/*use CONFIG_SYS_TEXT_BASE as temporary storage area */
-	header = (struct image_header *)(CONFIG_SYS_TEXT_BASE);
+	header = spl_get_load_buffer(0, sizeof(*header));
+
 #ifdef CONFIG_SPL_OS_BOOT
 	if (!spl_start_uboot()) {
 		/*

common/spl/spl_onenand.c

@@ -21,8 +21,7 @@ static int spl_onenand_load_image(struct spl_image_info *spl_image,
 
 	debug("spl: onenand\n");
 
-	/*use CONFIG_SYS_TEXT_BASE as temporary storage area */
-	header = (struct image_header *)(CONFIG_SYS_TEXT_BASE);
+	header = spl_get_load_buffer(0, CONFIG_SYS_ONENAND_PAGE_SIZE);
 	/* Load u-boot */
 	onenand_spl_load_image(CONFIG_SYS_ONENAND_U_BOOT_OFFS,
 		CONFIG_SYS_ONENAND_PAGE_SIZE, (void *)header);

common/spl/spl_ram.c

@@ -63,8 +63,9 @@ static int spl_ram_load_image(struct spl_image_info *spl_image,
 			 * No binman support or no information. For now, fix it
 			 * to the address pointed to by U-Boot.
 			 */
-			u_boot_pos = CONFIG_SYS_TEXT_BASE -
-					sizeof(struct image_header);
+			header = spl_get_load_buffer(-sizeof(*header),
+						     sizeof(*header));
+
 		}
 		header = (struct image_header *)map_sysmem(u_boot_pos, 0);
 

common/spl/spl_spi.c

@@ -88,8 +88,7 @@ static int spl_spi_load_image(struct spl_image_info *spl_image,
 		return -ENODEV;
 	}
 
-	/* use CONFIG_SYS_TEXT_BASE as temporary storage area */
-	header = (struct image_header *)(CONFIG_SYS_TEXT_BASE);
+	header = spl_get_load_buffer(-sizeof(*header), 0x40);
 
 #if CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA)
 	payload_offs = fdtdec_get_config_int(gd->fdt_blob,

common/spl/spl_ubi.c

@@ -61,8 +61,7 @@ int spl_ubi_load_image(struct spl_image_info *spl_image,
 		puts("Loading Linux failed, falling back to U-Boot.\n");
 	}
 #endif
-	header = (struct image_header *)
-		(CONFIG_SYS_TEXT_BASE - sizeof(struct image_header));
+	header = spl_get_load_buffer(-sizeof(*header), sizeof(header));
 	volumes[0].vol_id = CONFIG_SPL_UBI_LOAD_MONITOR_ID;
 	volumes[0].load_addr = (void *)header;
 

include/spl.h

@@ -303,4 +303,13 @@ void board_return_to_bootrom(void);
  *                        the boot-payload
  */
 void spl_perform_fixups(struct spl_image_info *spl_image);
+
+/*
+ * spl_get_load_buffer() - get buffer for loading partial image data
+ *
+ * Returns memory area which can be populated by partial image data,
+ * ie. uImage or fitImage header.
+ */
+struct image_header *spl_get_load_buffer(ssize_t offset, size_t size);
+
 #endif