[openwrt/openwrt] ath79: lzma-loader: allow setting custom kernel magic

[LEDE Commits]

ynezz pushed a commit to openwrt/openwrt.git, branch openwrt-21.02:
https://git.openwrt.org/1f6ec4b29ebfda19d9df01f1cc289ed6454683cf

commit 1f6ec4b29ebfda19d9df01f1cc289ed6454683cf
Author: Michael Pratt <mcpratt at pm.me>
AuthorDate: Wed Feb 24 22:35:37 2021 -0500

    ath79: lzma-loader: allow setting custom kernel magic
    
    ...and max flash offset
    
    The mtdsplit parser was recently refactored
    to allow the kernel to have custom image header magic.
    
    Let's also do this for the lzma-loader
    
    For example:
    When implemented together,
    this allows the kernel to "appear" to be a rootfs
    by OEM software in order to write an image
    that is actually kernel + rootfs.
    
    At the same time,
    it would boot to openwrt normally
    by setting the same magic in DTS.
    
    Both of the variables
    have a default value that is unchanged
    when not defined in the makefiles
    
    This has no effect on the size of the loader
    when lzma compressed.
    
    Signed-off-by: Michael Pratt <mcpratt at pm.me>
    (cherry picked from commit 1b8bd17c2d07c7397015a86941db9e114e1d349a)
---
 target/linux/ath79/image/Makefile                 | 6 +++++-
 target/linux/ath79/image/lzma-loader/Makefile     | 2 ++
 target/linux/ath79/image/lzma-loader/src/Makefile | 5 +++++
 target/linux/ath79/image/lzma-loader/src/loader.c | 4 ++++
 4 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/target/linux/ath79/image/Makefile b/target/linux/ath79/image/Makefile
index c2d2474336..d8b8800d91 100644
--- a/target/linux/ath79/image/Makefile
+++ b/target/linux/ath79/image/Makefile
@@ -4,6 +4,7 @@ include $(INCLUDE_DIR)/image.mk
 KERNEL_LOADADDR = 0x80060000
 
 DEVICE_VARS += LOADER_FLASH_OFFS LOADER_TYPE
+DEVICE_VARS += LOADER_FLASH_MAX LOADER_KERNEL_MAGIC
 DEVICE_VARS += NETGEAR_BOARD_ID NETGEAR_HW_ID
 DEVICE_VARS += RAS_BOARD RAS_ROOTFS_SIZE RAS_VERSION
 
@@ -30,7 +31,10 @@ define Build/loader-kernel
 endef
 
 define Build/loader-okli-compile
-	$(call Build/loader-common,FLASH_OFFS=$(LOADER_FLASH_OFFS) FLASH_MAX=0)
+	$(call Build/loader-common, \
+		FLASH_OFFS=$(LOADER_FLASH_OFFS) \
+		FLASH_MAX=$(LOADER_FLASH_MAX) \
+		KERNEL_MAGIC=$(LOADER_KERNEL_MAGIC) )
 endef
 
 # Arguments: <output name> <kernel offset>
diff --git a/target/linux/ath79/image/lzma-loader/Makefile b/target/linux/ath79/image/lzma-loader/Makefile
index 0ff59bc56a..2b1ed82a98 100644
--- a/target/linux/ath79/image/lzma-loader/Makefile
+++ b/target/linux/ath79/image/lzma-loader/Makefile
@@ -13,6 +13,7 @@ LOADADDR	:= 0x80060000
 LOADER		:= loader.bin
 LOADER_NAME	:= $(basename $(notdir $(LOADER)))
 LOADER_DATA	:=
+KERNEL_MAGIC	:=
 TARGET_DIR	:=
 FLASH_OFFS	:=
 FLASH_MAX	:=
@@ -41,6 +42,7 @@ loader-compile: $(PKG_BUILD_DIR)/.prepared
 		LZMA_TEXT_START=$(LZMA_TEXT_START) \
 		LOADADDR=$(LOADADDR) \
 		LOADER_DATA=$(LOADER_DATA) \
+		KERNEL_MAGIC=$(KERNEL_MAGIC) \
 		FLASH_OFFS=$(FLASH_OFFS) \
 		FLASH_MAX=$(FLASH_MAX) \
 		BOARD="$(BOARD)" \
diff --git a/target/linux/ath79/image/lzma-loader/src/Makefile b/target/linux/ath79/image/lzma-loader/src/Makefile
index 7773f027a2..c7bb935a03 100644
--- a/target/linux/ath79/image/lzma-loader/src/Makefile
+++ b/target/linux/ath79/image/lzma-loader/src/Makefile
@@ -18,6 +18,7 @@
 LOADADDR	:=
 LZMA_TEXT_START	:= 0x80a00000
 LOADER_DATA	:=
+KERNEL_MAGIC	:=
 BOARD		:=
 FLASH_OFFS	:=
 FLASH_MAX	:=
@@ -54,6 +55,10 @@ OBJECTS		+= data.o
 CFLAGS		+= -DLZMA_WRAPPER=1 -DLOADADDR=$(LOADADDR)
 endif
 
+ifneq ($(strip $(KERNEL_MAGIC)),)
+CFLAGS		+= -DCONFIG_KERNEL_MAGIC=$(KERNEL_MAGIC)
+endif
+
 ifneq ($(strip $(KERNEL_CMDLINE)),)
 CFLAGS		+= -DCONFIG_KERNEL_CMDLINE='"$(KERNEL_CMDLINE)"'
 endif
diff --git a/target/linux/ath79/image/lzma-loader/src/loader.c b/target/linux/ath79/image/lzma-loader/src/loader.c
index 794c4b6285..0213e94574 100644
--- a/target/linux/ath79/image/lzma-loader/src/loader.c
+++ b/target/linux/ath79/image/lzma-loader/src/loader.c
@@ -189,7 +189,11 @@ static void lzma_init_data(void)
 
 		p = flash_base + flash_ofs;
 		magic = get_be32(p);
+#ifdef CONFIG_KERNEL_MAGIC
+		if (magic == CONFIG_KERNEL_MAGIC) {
+#else
 		if (magic == IH_MAGIC_OKLI) {
+#endif
 			hdr = (struct image_header *) p;
 			break;
 		}