build: add initial Bootloader implementation

Signed-off-by: EnderIce2 <enderice2@protonmail.com>

Bootloader/firmware/aarch64/Makefile

@@ -0,0 +1,64 @@
+define find-sources
+	$(shell find ./ -type f -name '$1' $(shell echo $(foreach board,$(filter-out $(BOARD_TYPE),$(AVAILABLE_BOARDS)), -not -path \"./$(board)/*\")) -print0 | xargs -0)
+endef
+
+S_SOURCES := $(call find-sources,*.S)
+s_SOURCES := $(call find-sources,*.s)
+C_SOURCES := $(call find-sources,*.c)
+
+define find-common-sources
+	$(shell find ../../common -type f -name '$1' -print0 | xargs -0)
+endef
+
+C_COMMON_SOURCES := $(call find-common-sources,*.c)
+
+OBJ = $(s_SOURCES:.s=.o) $(S_SOURCES:.S=.o) $(C_SOURCES:.c=.o) $(C_COMMON_SOURCES:.c=.o)
+
+LDFLAGS = -static -nostdlib -nodefaultlibs -nolibc \
+	-Wl,-static,--no-dynamic-linker,-ztext 	\
+	-zmax-page-size=0x1000					\
+	-Wl,-Map boot.map -fno-pic -fno-pie
+
+CFLAGS :=										\
+	$(INCLUDE_DIR)								\
+	-D__kernel__='1'							\
+	-DGIT_COMMIT='"$(GIT_COMMIT)"'				\
+	-DGIT_COMMIT_SHORT='"$(GIT_COMMIT_SHORT)"'	\
+	-fno-pic -fno-pie -fno-builtin -I../../include
+
+CFLAGS += -mcmodel=large
+LDFLAGS += -T$(BOARD_TYPE)/linker.ld
+
+ifeq ($(DEBUG), 1)
+	CFLAGS += -DDEBUG -ggdb3 -O0 -fdiagnostics-color=always
+#	CFLAGS += -fsanitize=undefined
+	CFLAGS += -fstack-check -fverbose-asm
+	LDFLAGS += -ggdb3 -O0
+	ASFLAGS += -g --gstabs+ --gdwarf-5 -D
+endif # DEBUG
+
+default:
+	$(error Do not run this Makefile directly!)
+
+build: boot.bin
+
+boot.bin: $(OBJ)
+	$(info Linking $@)
+	$(CC) $(LDFLAGS) $(OBJ) -o tmp.elf
+	$(OBJCOPY) tmp.elf -O binary ../../boot.bin
+#	rm tmp.elf
+
+%.o: %.c $(HEADERS)
+	$(info Compiling $<)
+	$(CC) $(CFLAGS) -fstack-protector-all -std=c17 -c $< -o $@
+
+%.o: %.S
+	$(info Compiling $<)
+	$(AS) $(ASFLAGS) -c $< -o $@
+
+%.o: %.s
+	$(info Compiling $<)
+	$(AS) $(ASFLAGS) -c $< -o $@
+
+clean:
+	rm -f $(OBJ) boot.map

Bootloader/firmware/aarch64/raspi3

@@ -0,0 +1 @@
+./raspi4

Bootloader/firmware/aarch64/raspi4/boot.S

@@ -0,0 +1,49 @@
+/*
+	This file is part of Lynx Bootloader.
+
+	Lynx Bootloader is free software: you can redistribute it and/or
+	modify it under the terms of the GNU General Public License as
+	published by the Free Software Foundation, either version 3 of
+	the License, or (at your option) any later version.
+
+	Lynx Bootloader is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with Lynx Bootloader. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+.section ".text.boot"
+
+.extern __bss_start
+.extern __bss_end
+.extern __bss_size
+
+.global _start
+_start:
+	/* Keep only the main core */
+	mrs x1, mpidr_el1
+	and x1, x1, #3
+	cbz x1, 2f
+
+	/* Halt */
+1:	wfe
+	b 1b
+
+	/* Initialize the stack */
+2:	ldr x1, =_start
+	mov sp, x1
+
+	/* Clear the BSS */
+	ldr x1, =__bss_start
+	ldr w2, =__bss_size
+3:	cbz w2, 4f
+	str xzr, [x1], #8
+	sub w2, w2, #1
+	cbnz w2, 3b
+
+	/* Start the kernel */
+4:	bl _aarch64_start
+	b 1b

Bootloader/firmware/aarch64/raspi4/init.c

@@ -0,0 +1,32 @@
+/*
+	This file is part of Lynx Bootloader.
+
+	Lynx Bootloader is free software: you can redistribute it and/or
+	modify it under the terms of the GNU General Public License as
+	published by the Free Software Foundation, either version 3 of
+	the License, or (at your option) any later version.
+
+	Lynx Bootloader is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with Lynx Bootloader. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#include <types.h>
+
+uintptr_t __stack_chk_guard = 0;
+
+__noreturn __no_stack_protector void __stack_chk_fail(void)
+{
+	while (1)
+		;
+}
+
+int main();
+__attribute__((section(".bootstrap.text"))) void _aarch64_start(uint64_t dtb_ptr32, uint64_t x1, uint64_t x2, uint64_t x3)
+{
+	main();
+}

Bootloader/firmware/aarch64/raspi4/linker.ld

@@ -0,0 +1,70 @@
+/*
+	This file is part of Lynx Bootloader.
+
+	Lynx Bootloader is free software: you can redistribute it and/or
+	modify it under the terms of the GNU General Public License as
+	published by the Free Software Foundation, either version 3 of
+	the License, or (at your option) any later version.
+
+	Lynx Bootloader is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with Lynx Bootloader. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+OUTPUT_FORMAT("elf64-littleaarch64")
+OUTPUT_ARCH(aarch64)
+
+ENTRY(_start)
+
+SECTIONS
+{
+	. = 0x80000;
+	__start = .;
+	__text_start = .;
+	.text :
+	{
+		KEEP(*(.text.boot))
+		*(.text)
+	}
+	. = ALIGN(4096);
+	__text_end = .;
+
+	__rodata_start = .;
+	.rodata :
+	{
+		*(.rodata)
+	}
+	. = ALIGN(4096);
+	__rodata_end = .;
+
+	__data_start = .;
+	.data :
+	{
+		*(.data)
+	}
+	. = ALIGN(4096);
+	__data_end = .;
+
+	__bss_start = .;
+	.bss :
+	{
+		bss = .;
+		*(.bss)
+	}
+	. = ALIGN(4096);
+	__bss_end = .;
+	__bss_size = __bss_end - __bss_start; /* SIZEOF(.bss); */ 
+	__end = .;
+
+	/DISCARD/ :
+	{
+		*(.comment*)
+		*(.gnu*)
+		*(.note*)
+		*(.eh_frame*)
+	}
+}