bootm: Align cache flush begin address

commit b4d956f6bc0f ("bootm: Align cache flush end address correctly")
aligns the end address of the cache flush operation to a cache-line size to
ensure lower-layers in the code accept the range provided and flush.

A similar action should be taken for the begin address of a cache flush
operation. The load address may not be aligned to a cache-line boundary, so
ensure the passed address is aligned.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reported-by: Breno Matheus Lima <brenomatheus@gmail.com>
Suggested-by: Tom Rini <trini@konsulko.com>
Cc: Simon Glass <sjg@chromium.org>
Tested-by: Breno Lima <breno.lima@nxp.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

common/bootm.c

@@ -434,6 +434,8 @@ static int bootm_load_os(bootm_headers_t *images, unsigned long *load_end,
 	ulong blob_end = os.end;
 	ulong image_start = os.image_start;
 	ulong image_len = os.image_len;
+	ulong flush_start = ALIGN_DOWN(load, ARCH_DMA_MINALIGN);
+	ulong flush_len = *load_end - load;
 	bool no_overlap;
 	void *load_buf, *image_buf;
 	int err;
@@ -447,7 +449,11 @@ static int bootm_load_os(bootm_headers_t *images, unsigned long *load_end,
 		bootstage_error(BOOTSTAGE_ID_DECOMP_IMAGE);
 		return err;
 	}
-	flush_cache(load, ALIGN(*load_end - load, ARCH_DMA_MINALIGN));
+
+	if (flush_start < load)
+		flush_len += load - flush_start;
+
+	flush_cache(flush_start, ALIGN(flush_len, ARCH_DMA_MINALIGN));
 
 	debug("   kernel loaded at 0x%08lx, end = 0x%08lx\n", load, *load_end);
 	bootstage_mark(BOOTSTAGE_ID_KERNEL_LOADED);