[PATCH] kexec:arm: support zImage with appended device tree

[Hoeun Ryu]

Arm linux supports zImage with appended dtb (CONFIG_ARM_APPENDED_DTB) and
the concatenated image is generated like `cat zImage dtb > zImage_w_dtb`.

This patch is to support the concatednated zImage. This changes the
priority of source of dtb file.

 1. --dtb dtb_file
 2. zImage_w_dtb	<= newly added
 3. /sys/firmware/fdt
 4. /proc/device-tree

Users don't need to specify dtb file in the command line and don't have to
have /sys/firmware/fdt or /proc/device-tree if dtb is available in zImage.

Signed-off-by: Hoeun Ryu <hoeun.ryu at gmail.com>
---
 kexec/arch/arm/kexec-arm.h        |  1 +
 kexec/arch/arm/kexec-zImage-arm.c | 47 ++++++++++++++++++++++++++++++---------
 2 files changed, 37 insertions(+), 11 deletions(-)

diff --git a/kexec/arch/arm/kexec-arm.h b/kexec/arch/arm/kexec-arm.h
index a74cce2..94695b7 100644
--- a/kexec/arch/arm/kexec-arm.h
+++ b/kexec/arch/arm/kexec-arm.h
@@ -4,6 +4,7 @@
 #include <sys/types.h>
 
 #define SYSFS_FDT "/sys/firmware/fdt"
+#define APPENDED_FDT ((char *)-1) /* it doesn't mean to be opened. */
 #define BOOT_BLOCK_VERSION 17
 #define BOOT_BLOCK_LAST_COMP_VERSION 16
 
diff --git a/kexec/arch/arm/kexec-zImage-arm.c b/kexec/arch/arm/kexec-zImage-arm.c
index 7f02b93..59f0003 100644
--- a/kexec/arch/arm/kexec-zImage-arm.c
+++ b/kexec/arch/arm/kexec-zImage-arm.c
@@ -390,6 +390,7 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
 	initrd_size = 0;
 	use_atags = 0;
 	dtb_file = NULL;
+	dtb_buf = NULL;
 	while((opt = getopt_long(argc, argv, short_options, options, 0)) != -1) {
 		switch(opt) {
 		default:
@@ -424,14 +425,6 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
 		return -1;
 	}
 
-	if (!use_atags && !dtb_file) {
-		int f;
-
-		f = have_sysfs_fdt();
-		if (f)
-			dtb_file = SYSFS_FDT;
-	}
-
 	if (command_line) {
 		command_line_len = strlen(command_line) + 1;
 		if (command_line_len > COMMAND_LINE_SIZE)
@@ -440,9 +433,6 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
 	if (ramdisk)
 		ramdisk_buf = slurp_file(ramdisk, &initrd_size);
 
-	if (dtb_file)
-		dtb_buf = slurp_file(dtb_file, &dtb_length);
-
 	if (len > 0x34) {
 		const struct zimage_header *hdr;
 		off_t size;
@@ -459,6 +449,25 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
 				  (unsigned long long)size,
 				  (unsigned long long)len);
 
+			/* check if zImage has an appended dtb */
+			if (!dtb_file) {
+				if (fdt_check_header(buf + size) == 0) {
+					/*
+					 * dtb_file won't be opened. It's set
+					 * just to pass NULL checking.
+					 */
+					dtb_file = APPENDED_FDT;
+					dtb_length = fdt_totalsize(buf + size);
+					dtb_buf = xmalloc(dtb_length);
+					memcpy(dtb_buf, buf+size, dtb_length);
+
+					dbgprintf("found appended dtb, size 0x%llx\n",
+						  (unsigned long long)dtb_length);
+
+
+				}
+			}
+
 			if (size > len) {
 				fprintf(stderr,
 					"zImage is truncated - file 0x%llx vs header 0x%llx\n",
@@ -575,6 +584,22 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
 		initrd_base = kernel_base + _ALIGN(len * 5, getpagesize());
 	}
 
+	if (!use_atags && !dtb_file) {
+		int f;
+
+		f = have_sysfs_fdt();
+		if (f)
+			dtb_file = SYSFS_FDT;
+	}
+
+	/*
+	 * dtb_buf can be allocated when checking zImage_with_dtb.
+	 * dtb_buf won't be allocated in the logic if dtb_file is handed over
+	 * in argv[].
+	 */
+	if (dtb_file && !dtb_buf)
+		dtb_buf = slurp_file(dtb_file, &dtb_length);
+
 	if (use_atags) {
 		/*
 		 * use ATAGs from /proc/atags
-- 
2.7.4