From 75dfcd07a97a65dc86ad66080c56216406dd3e1f Mon Sep 17 00:00:00 2001
From: TuxSH <tuxsh@sfr.fr>
Date: Mon, 7 May 2018 01:02:23 +0200
Subject: [PATCH] Add chainloader (stage2) (need to edit more files)

---
 fusee/fusee-secondary/linker.ld         | 44 +++++++++++++++++--------
 fusee/fusee-secondary/src/chainloader.c | 12 +++++++
 fusee/fusee-secondary/src/chainloader.h | 13 ++++++++
 fusee/fusee-secondary/src/start.s       | 12 ++++++-
 4 files changed, 67 insertions(+), 14 deletions(-)
 create mode 100644 fusee/fusee-secondary/src/chainloader.c
 create mode 100644 fusee/fusee-secondary/src/chainloader.h

diff --git a/fusee/fusee-secondary/linker.ld b/fusee/fusee-secondary/linker.ld
index c5a94b7d8..fca868305 100644
--- a/fusee/fusee-secondary/linker.ld
+++ b/fusee/fusee-secondary/linker.ld
@@ -3,6 +3,12 @@ OUTPUT_ARCH(arm)
 ENTRY(_start)
 
 /* Mostly copied from https://github.com/devkitPro/buildscripts/blob/master/dkarm-eabi/crtls/3dsx.ld */
+MEMORY
+{
+    NULL        : ORIGIN = 0x00000000, LENGTH = 0x1000
+    main        : ORIGIN = 0xFFF00000, LENGTH = 0x00100000
+    low_iram    : ORIGIN = 0x40003000, LENGTH = 0x4000
+}
 
 SECTIONS
 {
@@ -30,7 +36,7 @@ SECTIONS
         /* .fini */
         KEEP( *(.fini) )
         . = ALIGN(4);
-    }
+    } >main
 
     .rodata :
     {
@@ -41,14 +47,14 @@ SECTIONS
         *(.gnu.linkonce.r*)
         SORT(CONSTRUCTORS)
         . = ALIGN(4);
-    }
+    } >main
 
     .preinit_array ALIGN(4) :
     {
         PROVIDE (__preinit_array_start = .);
         KEEP (*(.preinit_array))
         PROVIDE (__preinit_array_end = .);
-    }
+    } >main
 
     .init_array ALIGN(4) :
     {
@@ -56,7 +62,7 @@ SECTIONS
         KEEP (*(SORT(.init_array.*)))
         KEEP (*(.init_array))
         PROVIDE (__init_array_end = .);
-    }
+    } >main
 
     .fini_array ALIGN(4) :
     {
@@ -64,7 +70,7 @@ SECTIONS
         KEEP (*(.fini_array))
         KEEP (*(SORT(.fini_array.*)))
         PROVIDE (__fini_array_end = .);
-    }
+    } >main
 
     .ctors ALIGN(4) :
     {
@@ -72,7 +78,7 @@ SECTIONS
         KEEP (*(EXCLUDE_FILE (*crtend.o) .ctors))
         KEEP (*(SORT(.ctors.*)))
         KEEP (*(.ctors))
-    }
+    } >main
 
     .dtors ALIGN(4) :
     {
@@ -80,11 +86,11 @@ SECTIONS
         KEEP (*(EXCLUDE_FILE (*crtend.o) .dtors))
         KEEP (*(SORT(.dtors.*)))
         KEEP (*(.dtors))
-    }
+    } >main
 
-    .ARM.extab : { *(.ARM.extab* .gnu.linkonce.armextab.*) }
+    .ARM.extab : { *(.ARM.extab* .gnu.linkonce.armextab.*) } >main
     __exidx_start = .;
-    ARM.exidx : { *(.ARM.exidx* .gnu.linkonce.armexidx.*) }
+    ARM.exidx : { *(.ARM.exidx* .gnu.linkonce.armexidx.*) } >main
     __exidx_end = .;
 
     .data :
@@ -94,19 +100,31 @@ SECTIONS
         *(.gnu.linkonce.d*)
         CONSTRUCTORS
         . = ALIGN(4);
-    }
+    } >main
+
+    .chainloader :
+    {
+        . = ALIGN(32);
+        KEEP(*(.chainloader.text.start))
+        build/chainloader.o(.text*)
+        build/chainloader.o(.rodata*)
+        build/chainloader.o(.data*)
+        . = ALIGN(8);
+        build/chainloader.o(.bss*)
+        . = ALIGN(32);
+    } >low_iram
 
-    __bss_start__ = ALIGN(32);
     .bss :
     {
+        __bss_start__ = ALIGN(32);
         *(.dynbss)
         *(.bss)
         *(.bss.*)
         *(.gnu.linkonce.b*)
         *(COMMON)
         . = ALIGN(8);
-    }
-    __bss_end__ = .;
+        __bss_end__ = .;
+    } >main
     __end__ = ABSOLUTE(.) ;
 
     /* ==================
diff --git a/fusee/fusee-secondary/src/chainloader.c b/fusee/fusee-secondary/src/chainloader.c
new file mode 100644
index 000000000..144095353
--- /dev/null
+++ b/fusee/fusee-secondary/src/chainloader.c
@@ -0,0 +1,12 @@
+#include "chainloader.h"
+
+uint8_t g_payload_arg_data[PAYLOAD_ARG_DATA_MAX_SIZE] = {1};
+
+#pragma GCC optimize (3)
+void relocate_and_chainload_main(uintptr_t load_address, uintptr_t src_address, size_t size, int argc) {
+    for(size_t i = 0; i < size; i++) {
+        *(uint8_t *)(load_address + i) = *(uint8_t *)(src_address + i);
+    }
+
+    ((void (*)(int, void *))load_address)(argc, g_payload_arg_data);
+}
diff --git a/fusee/fusee-secondary/src/chainloader.h b/fusee/fusee-secondary/src/chainloader.h
new file mode 100644
index 000000000..19010d284
--- /dev/null
+++ b/fusee/fusee-secondary/src/chainloader.h
@@ -0,0 +1,13 @@
+#ifndef FUSEE_CHAINLOADER_H
+#define FUSEE_CHAINLOADER_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#define PAYLOAD_ARG_DATA_MAX_SIZE 0x1000
+
+extern uint8_t g_payload_arg_data[PAYLOAD_ARG_DATA_MAX_SIZE];
+
+void relocate_and_chainload(uintptr_t load_address, uintptr_t src_address, size_t size, int argc);
+
+#endif
diff --git a/fusee/fusee-secondary/src/start.s b/fusee/fusee-secondary/src/start.s
index 5a060b0be..b90b9b12f 100644
--- a/fusee/fusee-secondary/src/start.s
+++ b/fusee/fusee-secondary/src/start.s
@@ -2,10 +2,11 @@
     mov r\@, #0
 .endm
 
-.section .text.start
+.section .text.start, "ax", %progbits
 .arm
 .align 5
 .global _start
+.type   _start, %function
 _start:
     /* Insert NOPs for convenience (i.e. to use Nintendo's BCTs, for example) */
     .rept 16
@@ -57,3 +58,12 @@ _start:
     ldmfd sp!, {r0, r1}
     bl  main
     b   .
+
+.section .chainloader.text.start, "ax", %progbits
+.arm
+.align 5
+.global relocate_and_chainload
+.type   relocate_and_chainload, %function
+relocate_and_chainload:
+    ldr sp, =0x40010000
+    b   relocate_and_chainload_main