arch: arm: Implement TEXT_BASE instead of using a hardcoded address

This was an issue for other armv7 boards that have slightly different
addresses till now. This also allows to start working on relocation
in the near future for both armv7 and aarch64.

While we're at it, fix some mistakes here and there.

Signed-off-by: Ivaylo Ivanov <ivo.ivanov.ivanov1@gmail.com>

Makefile

@@ -103,6 +103,7 @@ export srctree objtree VPATH
 CROSS_COMPILE	?= $(CONFIG_CROSS_COMPILE:"%"=%)
 KERNEL_PATH	?= $(CONFIG_KERNEL_PATH:"%"=%)
 DT_PATH	?= $(CONFIG_DT_PATH:"%"=%)
+TEXT_BASE	?= $(CONFIG_TEXT_BASE:"%"=%)
 
 KCONFIG_CONFIG	?= .config
 export KCONFIG_CONFIG
@@ -360,7 +361,7 @@ quiet_cmd_uniLoader = LD      $@.o
       cmd_uniLoader = $(LD) $(main-y) $(uniLoader-libs) -o $@.o --script=arch/$(ARCH)/linker.lds
 
 arch/$(ARCH)/linker.lds: arch/$(ARCH)/linker.lds.S $(KERNEL_PATH)
-	$(CPP) $< -DKERNEL_PATH=$(KERNEL_PATH) -DDTB_PATH=$(DT_PATH) -P -o $@
+	$(CPP) $< -DTEXT_BASE=$(TEXT_BASE) -DKERNEL_PATH=$(KERNEL_PATH) -DDTB_PATH=$(DT_PATH) -P -o $@
 
 uniLoader: $(uniLoader-all)
 	$(call if_changed,uniLoader)

arch/arm/Start.S

@@ -2,7 +2,9 @@
 /*
  * Copyright (c) 2022, Ivaylo Ivanov <ivo.ivanov.ivanov1@gmail.com>
  */
+.global _start
 
+_start:
     ldr r0, =dtb
     ldr r1, =kernel
     b main

arch/arm/linker.lds.S

@@ -9,7 +9,9 @@ INPUT(DTB_PATH)
 
 SECTIONS
 {
-        . = 0x80008000;
+	/* The default TEXT_BASE address is 0x0 if not specified otherwise, so compare it to 0x1 */
+        __start_address = (TEXT_BASE > 0x1) ? TEXT_BASE : 0x80008000;
+        . = __start_address;
 	
         .boot : {
                 arch/arm/Start.o

board/Kconfig

@@ -55,23 +55,27 @@ menu "Device Support"
 		help
 		  Say Y if you want to include support for Samsung Galaxy S20
 
-	config SAMSUNG_J5LTE
-		bool "Support for Samsung Galaxy J5 2015"
-		default n
-		depends on QC32_8916
-		help
-		  Say Y if you want to include arm32 support for Samsung Galaxy J5 2015
-	
 	config SAMSUNG_J4LTE
 		bool "Support for Samsung Galaxy J4 2018"
 		default n
 		depends on EXYNOS_7570
 		help
 		  Say Y if you want to include arm64 support for Samsung Galaxy J4 2018
+
+	config SAMSUNG_J5LTE
+		bool "Support for Samsung Galaxy J5 2015"
+		default n
+		depends on QC32_8916
+		help
+		  Say Y if you want to include arm32 support for Samsung Galaxy J5 2015
 endmenu
 
 menu "Device Specific Addresses"
 
+	config TEXT_BASE
+		hex "UniLoader Text Base"
+		default 0x0
+
 	config PAYLOAD_ENTRY
 		hex "Payload Entry Address"
 		default 0x830000000 if APPLE_N61AP
@@ -82,9 +86,8 @@ menu "Device Specific Addresses"
 		default 0x090000000 if SAMSUNG_DREAMLTE
 		default 0x090000000 if SAMSUNG_STARLTE
 		default 0x090000000 if SAMSUNG_X1S
-		default 0x090000000 if SAMSUNG_J5LTE
 		default 0x050000000 if SAMSUNG_J4LTE
-
+		default 0x090000000 if SAMSUNG_J5LTE
 
 	config FRAMEBUFFER_BASE
 		hex "Framebuffer Base Address (for SimpleFB)"
@@ -97,8 +100,8 @@ menu "Device Specific Addresses"
 		default 0x0cc000000 if SAMSUNG_DREAMLTE
 		default 0x0cc000000 if SAMSUNG_STARLTE
 		default 0x0F1000000 if SAMSUNG_X1S
-		default 0x08e000000 if SAMSUNG_J5LTE
 		default 0x067000000 if SAMSUNG_J4LTE
+		default 0x08e000000 if SAMSUNG_J5LTE
 
 	config FRAMEBUFFER_WIDTH
 		int "Framebuffer Width (for SimpleFB)"
@@ -111,8 +114,8 @@ menu "Device Specific Addresses"
 		default 1440 if SAMSUNG_DREAMLTE
 		default 1440 if SAMSUNG_STARLTE
 		default 1440 if SAMSUNG_X1S
-		default 720 if SAMSUNG_J5LTE
 		default 720 if SAMSUNG_J4LTE
+		default 720 if SAMSUNG_J5LTE
 
 	config FRAMEBUFFER_HEIGHT
 		int "Framebuffer Height (for SimpleFB)"
@@ -125,8 +128,8 @@ menu "Device Specific Addresses"
 		default 2960 if SAMSUNG_DREAMLTE
 		default 2960 if SAMSUNG_STARLTE
 		default 3200 if SAMSUNG_X1S
-		default 1280 if SAMSUNG_J5LTE
 		default 1280 if SAMSUNG_J4LTE
+		default 1280 if SAMSUNG_J5LTE
 
 	config FRAMEBUFFER_STRIDE
 		int "Framebuffer Stride (for SimpleFB)"
@@ -139,8 +142,8 @@ menu "Device Specific Addresses"
 		default 4 if SAMSUNG_DREAMLTE
 		default 4 if SAMSUNG_STARLTE
 		default 4 if SAMSUNG_X1S
-		default 3 if SAMSUNG_J5LTE
 		default 4 if SAMSUNG_J4LTE
+		default 3 if SAMSUNG_J5LTE
 
 	config FRAMEBUFFER_BGRA
 		bool "Framebuffer BGRA (for SimpleFB)"

configs/j5lte_defconfig

@@ -1,3 +1,4 @@
 CONFIG_CROSS_COMPILE="arm-none-eabi-"
+CONFIG_TEXT_BASE=0x80008000
 CONFIG_SAMSUNG_J5LTE=y
 CONFIG_QC32_8916=y