x86: ifdtool: Drop microcode from the device tree when collating

When ifdtool collates the microcode into one place it effectively creates
a copy of the 'data' properties in the device tree microcode nodes. This
is wasteful since we now have two copies of the microcode in the ROM.

To avoid this, remove the microcode data from the device tree and shrink it
down. This means that there is only one copy and the overall ROM space used
by the microcode does not increase.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

1 files changed, 53 insertions, 2 deletions

diff --git a/tools/ifdtool.c b/tools/ifdtool.c
index d966c563da..1f95203eea 100644
--- a/tools/ifdtool.c
+++ b/tools/ifdtool.c
@@ -783,6 +783,47 @@ static int scan_ucode(const void *blob, char *ucode_base, int *countp,
 	return ucode - ucode_base;
 }
 
+static int remove_ucode(char *blob)
+{
+	int node, count;
+	int ret;
+
+	/* Keep going until we find no more microcode to remove */
+	do {
+		for (node = 0, count = 0; node >= 0;) {
+			int ret;
+
+			node = fdt_node_offset_by_compatible(blob, node,
+							     "intel,microcode");
+			if (node < 0)
+				break;
+
+			ret = fdt_delprop(blob, node, "data");
+
+			/*
+			 * -FDT_ERR_NOTFOUND means we already removed the
+			 * data for this one, so we just continue.
+			 * 0 means we did remove it, so offsets may have
+			 * changed and we need to restart our scan.
+			 * Anything else indicates an error we should report.
+			 */
+			if (ret == -FDT_ERR_NOTFOUND)
+				continue;
+			else if (!ret)
+				node = 0;
+			else
+				return ret;
+		}
+	} while (count);
+
+	/* Pack down to remove excees space */
+	ret = fdt_pack(blob);
+	if (ret)
+		return ret;
+
+	return fdt_totalsize(blob);
+}
+
 static int write_ucode(char *image, int size, struct input_file *fdt,
 		       int fdt_size, unsigned int ucode_ptr,
 		       int collate_ucode)
@@ -818,8 +859,8 @@ static int write_ucode(char *image, int size, struct input_file *fdt,
 	}
 
 	/*
-	 * Collect the microcode into a buffer and place it immediately above
-	 * the device tree.
+	 * Collect the microcode into a buffer, remove it from the device
+	 * tree and place it immediately above the (now smaller) device tree.
 	 */
 	if (collate_ucode && count > 1) {
 		ucode_buf = malloc(ucode_size);
@@ -833,7 +874,17 @@ static int write_ucode(char *image, int size, struct input_file *fdt,
 		if (ret < 0)
 			return ret;
 
+		/* Remove the microcode from the device tree */
+		ret = remove_ucode((char *)blob);
+		if (ret < 0) {
+			debug("Could not remove FDT microcode: %s\n",
+			      fdt_strerror(ret));
+			return -EINVAL;
+		}
 		debug("Collated %d microcode block(s)\n", count);
+		debug("Device tree reduced from %x to %x bytes\n",
+		      fdt_size, ret);
+		fdt_size = ret;
 
 		/*
 		 * Place microcode area immediately above the FDT, aligned